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Patellar instability is one of the most prevalent knee disorders, with dislocations occurring in 5 to 43 cases per 10,000 annually. Traumatic patellar dislocation can result in significant morbidity and is associated with patellofemoral chondral injuries and fractures, medial soft tissue disruption, pain, and reduced function, and can lead to patellofemoral osteoarthritis. Chronic and recurrent instability can lead to deformation and incompetence of the medial soft tissue stabilizers. Despite recent gains in understanding the pathoanatomy of this disorder, the management of patients with this condition is complex and remains enigmatic.

Study design Retrospective cohort. Summary of background data Heterotopic ossification (HO) about the hip is a debilitating condition that can occur after fixation for acetabular fractures, total hip replacement, or polytrauma with closed head injuries. No classification exists that informs surgical treatment. Purpose To establish a classification system for HO about the hip by reviewing a consecutive series of HO at a single institution. It was hypothesized that HO about the hip could be grouped into a novel classification scheme based upon the location and involved structures of the hip. Methods Retrospective chart review of single center's case log for HO excision from 2004 to 2018 was performed. Inclusion criteria included all patients undergoing excision of heterotopic bone excision about the hip. Demographic data, pre and post hip range of motion, surgical approach for each surgery, index surgery date and interval to excision are reported as well as presence and location of HO and Brooker classification. Results A total of 36 patients (21 men and 15 women) and 40 hips were identified meeting inclusion criteria. The mean age at the time of the index surgery was 47 (range, 16-77 years). Traumatic injury with fracture (35%) included 9 acetabular fractures (22%), 2 long bone fractures (5%) treated with intramedullary devices, one displaced femoral neck fracture (2%), and one pelvic ring injury (2%). Total hip arthroplasty accounted for 32% of patients. Brooker classification was type 4 (35%), 3 (25%), 2 (23%), 1(17%) which translated to 55% anterior, 48% posterior, 3% medial with respect to location. Average improvement in hip flexion and abduction was 22 and 8°, respectively. Conclusion This study identified discrete locations for heterotopic ossification following hip or acetabulum surgery. Both posterior and anterior structures are implicated in the formation of HO, and this investigation presents a novel classification to guide surgical approach for HO excision based upon location.

Osteochondral allograft transplantation (OCA) is a procedure that transfers mature hyaline articular cartilage into chondral or osteochondral defect(s) in the knee. By transplanting viable chondrocytes with their associated subchondral bone, the procedure may be performed in primary or salvage-type scenarios, with or without bone loss, for typically larger (>2 cm2) defects. Primary indications for OCA in the knee include large, full thickness chondral, or osteochondral lesions or revision/salvage of a previously failed cartilage repair. As a structural allograft with subchondral bone, OCAs may also be indicated in the setting of osteochondritis dissecans (OCD), osteonecrosis, or conjunction with other procedures after an intra-articular injury or fracture. Allograft storage capability, graft availability, and technically difficult surgical technique have historically been barriers to widespread OCA utilization, but novel graft storage methods and surgical guides have improved these factors, making OCA transplantation an excellent first–line option in the treatment of chondral and osteochondral defects in the knee.

Background: Various surgical treatment options exist for repairing, replacing, or regenerating tissue to fill osteochondral defects. Biologic augmentation has been increasingly studied as an adjunct in the surgical treatment of osteochondral defects of the knee in animal and human models. Purpose/Hypothesis: The purpose of the study was to systematically review use of platelet-rich plasma (PRP) and bone marrow concentrate (BMC) augmentation in the surgical treatment of osteochondral knee defects and to describe the outcomes. It was hypothesized that both PRP and BMC augmentation will result in improved outcomes in osteochondral knee surgery in both animal and human models. Study Design: Systematic review. Methods: PubMed, MEDLINE, and Embase were searched for studies relating to PRP or BMC and treatment of osteochondral defects of the knee, from database inception to February 1, 2020. Included were articles that (1) studied PRP or BMC augmentation; (2) used osteochondral autograft, allograft, or biologic scaffold; and (3) treated osteochondral defects in the knee. Data on use of PRP or BMC, outcomes assessed, and results were recorded for each publication. Results: Of the 541 articles identified initially, 17 were included in the final review. Five articles studied osteochondral grafts in animals, 5 studied biologic scaffolds in animals, and 7 studied scaffolds or allografts in humans; the combined sample size was 202 patients. Of 4 histologic scaffold studies, 3 PRP-augmented scaffold studies identified histologic improvements in regenerated cartilage in animal models, while 1 BMC study demonstrated similar improvement in histologic scores of BMC-augmented scaffolds compared with controls. Three studies associated greater collagen type 2 and glycosaminoglycan content with PRP treatment. Comparative studies found that both augments increase osteogenic proteins, including bone morphogenetic protein–2 and osteoprotegerin. Two of 3 studies on BMC-augmented osteochondral allografts reported no difference in radiographic features postoperatively. Long-term improvement in clinical and radiographic outcomes of PRP-augmented scaffolds was demonstrated in 1 human study. Conclusion: Animal studies suggest that biologics possess potential as adjuncts to surgical treatment of osteochondral knee defects; however, clinical data remain limited.

Background: Hip dislocation is a rare occurrence during sports but carries serious implications for athletes. Purpose: To systematically review treatment strategies and outcomes for hip dislocation in athletes, with the ultimate goal of providing sports medicine physicians with the information necessary to appropriately treat and counsel patients sustaining this injury. Study Design: Systematic review; Level of evidence, 4. Methods: PubMed, MEDLINE, and Embase were searched for studies relating to hip instability and athletics from January 1, 1989 to October 1, 2019. Abstracts and articles were evaluated on the basis of predefined inclusion and exclusion criteria. Inclusion criteria were the following: (1) data from ≥1 patients, (2) native hip dislocation or subluxation occurring during sports, (3) patients aged at least 10 years, and (4) written in English. Exclusion criteria were (1) patients younger than 10 years; (2) nonnative or postoperative hip dislocation or subluxation; (3) a native hip injury without dislocation or subluxation; (4) patients with dislocation or subluxation secondary to neuromuscular, developmental, or syndromic causes; (5) dislocation or subluxation not occurring during sports; (6) patients with physeal fractures; or (7) review articles or meta-analyses. Data were recorded on patient demographics, injury mechanism, treatment strategies, and clinical and radiographic outcomes. Where possible, pooled analysis was performed. Studies were grouped based on reported outcomes. Meta-analysis was then performed on these pooled subsets. Results: A total of 602 articles were initially identified, and after screening by 2 reviewers, 27 articles reporting on 145 patients were included in the final review. There were 2 studies that identified morphological differences between patients with posterior dislocation and controls, including decreased acetabular anteversion ( P = .015 and .068, respectively), increased prevalence of a cam deformity ( P < .0035), higher alpha angles ( P≤ .0213), and decreased posterior acetabular coverage ( P < .001). No differences were identified for the lateral center edge angle or Tonnis angle. Protected postreduction weightbearing was most commonly prescribed for 2 to 6 weeks, with 65% of reporting authors recommending touchdown, toe-touch, or crutch-assisted weightbearing. Recurrence was reported in 3% of cases. Overall, 4 studies reported on findings at hip arthroscopic surgery, including a 100% incidence of labral tears (n = 27; 4 studies), 92% incidence of chondral injuries, 20% incidence of capsular tears, and 84% incidence of ligamentum teres tears (n = 25; 2 studies). At final follow-up, 86% of patients reported no pain (n = 14; 12 studies), 87% reported a successful return to play (n = 39; 10 studies), and 11% had radiographic evidence of osteonecrosis (n = 38; 10 studies). Conclusion: Various treatment strategies have been described in the literature, and multiple methods have yielded promising clinical and radiographic outcomes in patients with native hip dislocation sustained during sporting activity. Data support nonoperative treatment with protected weightbearing for hips with concentric reduction and without significant fractures and an operative intervention to obtain concentric reduction if unachievable by closed means alone. Imaging for osteonecrosis is recommended, with evidence suggesting 4- to 6-week magnetic resonance imaging and follow-up at 3 months for those with suspicious findings in the femoral head.

Objective To determine the accuracy of International Classification of Disease Version 10 (ICD-10) coding for ankle fracture injury patterns. Design Retrospective cohort study Patients 97 adult patients with fractures about the ankle (rotational ankle fracture or distal tibia fracture) from 2016 to 2020, selected by stratified random sampling. Intervention Assignment of an ICD-10 code representative of a rotational ankle fracture, pilon fracture, or unspecified fracture of the lower leg. Outcome measurements Injury radiographs were reviewed by three authors to determine the correct code. Agreement between the correct code and the electronic medical record (EMR) assigned code was determined using kappa's statistic in the aggregate as well as percent agreement, sensitivity, specificity, and positive predictive value (PPV) between individual codes. Results 59 of 97 cases (60.8%) demonstrated discordance between the existing EMR and surgeon-assigned codes. Aggregate agreement between all codes was fair (K = 0.26). Lateral malleolus fracture codes demonstrated the highest PPV (0.91, 95% CI 0.72–0.99), while the lowest PPV was found for “other fractures of the lower leg” (0.05, 95% CI 0.0–0.24) and “other fracture of the fibula” (0.0, 95% CI 0.0–0.15). Generalized “other fracture” codes comprised 45% of EMR codes compared to only 6% of assigned codes (p Conclusion There is substantial discordance between existing EMR and surgeon-assigned ICD-10 codes for ankle fractures. Database research that relies on ICD-10 coding as a surrogate for primary clinical data should be interpreted with caution and institutions should make efforts to increase the accuracy of their coding.

Focal articular cartilage injury of the knee remains a common contributor to knee pain and may lead to debilitating outcomes for patients. Historically treated with microfracture with varying results, newer treatment alternatives, such as osteochondral autologous transplantation (OAT), osteochondral allograft transplantation (OCA), and autologous chondrocyte implantation (ACI), have been used to treat these lesions. This chapter reviews the indications and surgical technique for OAT in the knee joint, as well as the clinical outcomes and basic science supporting this technique. The surgical technique typically involves one of two procedures: the single plug or mosaicplasty; both of which are reviewed in this chapter. Clinical outcome studies have demonstrated promising initial results for OAT, with the need for further randomized controlled trials to evaluate the long-term effectiveness of OAT versus other available techniques.

Residual anterolateral rotatory laxity following injury and reconstruction of the anterior cruciate ligament (ACL) has become a popular topic and has generated interest in characterizing the relative contribution from the anterolateral structures of the knee. Studies have reported on the anatomic and biomechanical features of the anterolateral ligament (ALL), revealing a role in restraining internal tibial rotation in both ACL-intact and ACL-deficient knees. The Kaplan fibers of the iliotibial band have also been reported to provide significant restraint to internal tibial rotation. The ACL is the primary restraint to anterior tibial translation, and both the proximal and distal bundles of the iliotibial band, with a divergent orientation, also provide significant static restraint against internal tibial rotation, and each bundle may have a distinct individual role. In the setting of ACL deficiency, subsequent sectioning of the ALL and Kaplan fibers led to further increases in anterior tibial translation. Residual rotatory laxity that may be seen clinically following ACL reconstruction may be attributable to an associated anterolateral structure injury even in the setting of an anatomic ACLR, leading to consideration for a concomitant anterolateral structure reconstruction. Studies evaluating the kinematic influence of anatomic ALL reconstruction or lateral extra-articular tenodesis have focused on internal rotation, axial plane translation, and anterior tibial translation, with variable results having been reported. Further, despite the long history of anterolateral structure reconstruction, most commonly with a lateral extra-articular tenodesis, the clinical use of these combined techniques is still in its relative infancy, and long-term patient outcomes have yet to be published for relative comparisons.

Meniscal root tears are increasingly recognized as an important pathology. Failure to recognize this pathology could lead to early onset osteoarthritis of the ipsilateral knee joint compartment similar to a total meniscectomy. Therefore, surgical treatment is necessary to restore meniscal function and to normalize contact pressures, when there is joint overload and sufficient remaining articular cartilage. This article details our anatomic posterior root repair procedure using a transtibial double tunnel pullout technique.

Background:Although previous literature has described the relevant anatomy for an open anterior Bankart approach of the shoulder, there is little known regarding the anatomic relationship changes in the neurovascular structures after an open Latarjet procedure.Purpose:To define the neurovascular anatomy of the native shoulder in relation to the coracoid and to define the anatomy after the Latarjet procedure in relation to the glenoid to determine distances to these neurovascular structures with and without neurolysis of the musculocutaneous nerve (MCN) from the conjoint tendon.Study Design:Descriptive laboratory study.Methods:Fourteen fresh-frozen male cadaveric shoulders (7 matched pairs) were utilized. The distances of 7 neurovascular structures (the main trunk of the MCN at its insertion into the conjoint tendon, the MCN at its closest location to the coracoid process, the lateral cord of the plexus, the split of the lateral cord and MCN, the posterior cord of the plexus, the axillary nerve, and the axillary artery) to pertinent landmarks were first measured in the native state in relation to the coracoid. After the Latarjet procedure, these landmarks were measured in relation to the glenoid. In addition, measurements of the MCN distances were performed both with and without neurolysis of the MCN from the conjoint tendon. All measurements were performed using digital calipers and reported as medians with ranges.Results:The median MCN entry into the conjoint tendon was 56.5 mm (range, 43.0-82.2 mm) and 57.1 mm (range, 23.5-92.9 mm) from the tip of the coracoid in the neurolysis group and nonneurolysis group, respectively ( P = .32). After the Latarjet procedure, the median MCN entry into the conjoint tendon was 43.8 mm (range, 20.2-58.3 mm) and 35.6 mm (range, 27.3-84.5 mm) from the 3-o’clock position of the glenoid in the neurolysis and nonneurolysis groups, respectively ( P = .83). The median MCN entry into the conjoint tendon was 35.6 mm (range, 25.1-58.0 mm) and 36.3 mm (range, 24.4-77.9 mm) from the 6-o’clock position in the neurolysis group and nonneurolysis group, respectively ( P = .99). After the Latarjet procedure, the closest neurovascular structures in relation to both the 3-o’clock and 6-o’clock positions to the coracoid were the axillary nerve at a median 27.4 mm (range, 19.8-40.0 mm) and 27.7 mm (range, 23.2-36.1 mm), respectively.Conclusion:This study identified a minimum distance medial to the glenoid after the Latarjet procedure to be approximately 19.8 mm for the axillary nerve, 23.6 mm for the posterior cord, and 24.4 mm and 20.2 mm for the MCN without and with neurolysis, respectively. Neurolysis of the MCN did not significantly change the distance of the nerve from pertinent landmarks compared with no neurolysis, and routine neurolysis may not be indicated. However, the authors still advise that there may be clinical benefit to performing neurolysis during surgery, especially given that the short length of the MCN puts it at risk for traction injuries during the Latarjet procedure.Clinical Relevance:The findings of this study provide an improved understanding of the position of the neurovascular structures after the Latarjet procedure. Knowledge of these minimum distances will help avoid iatrogenic damage of the neurovascular structures when performing procedures involving transfer of the coracoid process.

Background: While the effects of concurrent meniscal resection and anterior cruciate ligament reconstruction (ACLR) are known to decrease patient outcomes and increase the rate of osteoarthritis over the long term, overall short-term patient functional outcomes in a large cohort of patients are not well known. Purpose/Hypothesis: The purpose of this study was to compare the preoperative and 2-year postoperative Knee Injury and Osteoarthritis Outcome Score (KOOS) subscale scores after ACLR with and without meniscal injury. The hypothesis was that, in comparison with an isolated ACLR, patients with a medial meniscal (MM) or lateral meniscal (LM) resection with an ACLR would have significantly decreased 2-year postoperative KOOS outcomes, while those with an ACLR with an MM or LM repair would be indistinguishable from isolated ACLR. Study Design: Cohort study; Level of evidence, 2. Methods: The Norwegian Knee Ligament Registry (NKLR) was used to evaluate outcomes for a total of 4691 patients with primary ACLR. The KOOS scoring system was used to evaluate patients on 5 subscales (Pain, Other Symptoms, Activities of Daily Life [ADL], Sport and Recreation Function, and Quality of Life [QoL]) at time of surgery and at 2-year postoperative follow-up. Patients with isolated ACLR and ACLR with LM repair, LM resection, MM repair, or MM resection were compared using multiple linear regression modeling. Results: Preoperatively, in comparison with isolated ACLR, patients who had an ACLR with either an MM repair or MM resection had significantly lower scores for all KOOS subscores, and LM repair had significantly decreased scores on the Other Symptoms, Pain, and ADL subscales. Postoperatively, in comparison with isolated ACLR, 2-year KOOS outcomes were not significantly different between patients with ACLR and LM repair, MM resection, or LM resection; however, those with MM repair had significantly lower scores on the Other Symptoms and QoL subscales. Conclusion: Patients with ACLR with meniscal resections do not exhibit decreased clinical outcomes at 2 years postoperatively. It is recommended that clinicians follow patients with ACLR and concurrent meniscal treatment for longer than 2 years postoperatively.

The posterior cruciate ligament (PCL) is recognized as an essential stabilizer of the knee. However, the complexity of the ligament has generated controversy about its definitive role and the recommended treatment after injury. A proper understanding of the functional role of the PCL is necessary to minimize residual instability, osteoarthritic progression, and failure of additional concomitant ligament graft reconstructions or meniscal repairs after treatment. Recent anatomic and biomechanical studies have elucidated the surgically relevant quantitative anatomy and confirmed the codominant role of the anterolateral and posteromedial bundles of the PCL. Although nonoperative treatment has historically been the initial treatment of choice for isolated PCL injury, possibly biased by the historically poorer objective outcomes postoperatively compared with anterior cruciate ligament reconstructions, surgical intervention has been increasingly used for isolated and combined PCL injuries. Recent studies have more clearly elucidated the biomechanical and clinical effects after PCL tears and resultant treatments. This article presents a thorough review of updates on the clinically relevant anatomy, epidemiology, biomechanical function, diagnosis, and current treatments for the PCL, with an emphasis on the emerging clinical and biomechanical evidence regarding each of the treatment choices for PCL reconstruction surgery. It is recommended that future outcomes studies use PCL stress radiographs to determine objective outcomes and that evidence level 1 and 2 studies be performed to assess outcomes between transtibial and tibial inlay reconstructions and also between single- and double-bundle PCL reconstructions.

A detailed understanding of the anatomy and biomechanics of the lateral knee is essential for the clinical diagnosis and surgical treatment of lateral-sided knee injuries. In the past, the structure and function of the lateral and posterolateral knee was poorly understood and was dubbed by some as "the dark side of the knee." However, recent advances in quantitative anatomy and biomechanics of this region have led to the development of anatomic-based reconstruction techniques and improved objective and subjective patient-based outcomes. Although the lateral knee consists of 28 unique structures, the primary lateral knee stabilizers include the fibular collateral ligament, popliteus tendon, and popliteofibular ligament. Together, these structures function to resist lateral compartment varus gapping and rotatory knee instability. This work will summarize the current state of knowledge regarding the anatomy and biomechanics of the lateral knee structures, while emphasizing implications for surgical treatment.

Fixed-loop suspension devices are currently considered the gold standard of cortical suspension devices. They have been demonstrated to be stable suspension devices due to their ability to resist slippage during biomechanical loading. However, due to their pre-determined loop length, fixed loop devices do not allow for customization to the specific anatomy of the patient receiving the graft. Therefore, adjustable loop devices have been developed which allow some adaptability to the unique anatomy of each patient. However, there is concern for the increased displacement reported in biomechanical studies for adjustable loop devices which could potentially lead to poorer outcomes and graft laxity. All current suspensory cortical fixation devices have displayed ultimate failure strengths more than satisfactory for postoperative rehabilitation protocols. Future studies should be aimed at attempting to decrease the amount of displacement for adjustable-loop fixation devices in femoral ACL graft reconstruction.

Background: Recent biomechanical evidence suggests that the meniscus-suture interface contributes the most displacement to the transtibial pull-out repair for meniscal root tears. Therefore, optimization of surgical technique at the meniscus-suture interface may minimize displacement and improve the strength of meniscal root repairs. Purpose/Hypothesis: The purpose of this study was to investigate the cyclic displacement and ultimate failure loads of 4 different meniscus-suture fixation techniques for posterior medial meniscal root repairs in human meniscus tissue. The hypothesis was that there would be no significant difference between the two simple sutures (TSS) technique and 3 other techniques in cyclic displacement or ultimate failure load. Study Design: Controlled laboratory study. Methods: A total of 32 fresh-frozen, human, medial meniscal transplant specimens were randomly assigned to 4 meniscus-suture fixation techniques used for transtibial pull-out repair in posterior medial meniscal root tears (n = 8 per group). The suture techniques studied were (1) TSS, (2) modified Mason-Allen (MMA), (3) single double-locking loop (S-DLL), and (4) double double-locking loop (D-DLL). The menisci were subjected to a cyclic tensioning protocol representative of postoperative rehabilitation (10-30 N for 1000 cycles) and pulled to failure at a rate of 0.5 mm/s. Results: After 1000 cycles, the TSS group displaced the least (mean ± SD, 1.78 ± 0.64 mm), followed by the MMA (2.14 ± 0.65 mm), D-DLL (2.97 ± 0.57 mm), and S-DLL (3.81 ± 0.78 mm) groups. After 100, 500, and 1000 cycles, suture displacements using the TSS and MMA techniques were not significantly different ( P > .13), while the TSS technique resulted in significantly less displacement than the S-DLL and D-DLL ( P < .03) techniques. The ultimate failure loads of the MMA (325 ± 77 N) and D-DLL (320 ± 50 N) techniques were significantly greater than those of the TSS (192 ± 52 N) and S-DLL (217 ± 51 N) techniques ( P < .05). Conclusion: The TSS and MMA fixation techniques were not significantly different, while the TSS was significantly better at resisting displacement when compared with the S-DLL and D-DLL stitch configurations. The MMA and D-DLL techniques exhibited significantly greater failure loads than did the TSS and S-DLL techniques; however, all techniques demonstrated ultimate failure loads above the currently accepted rehabilitation force threshold. Clinical Relevance: The TSS fixation technique combines the lowest technical difficulty and the ability to resist displacement at time zero. The MMA technique, although more technically challenging, may provide an alternative means to resist displacement while enhancing the failure load.

Case: This case series describes the surgical technique for and outcomes after a modified transtibial pull-out repair for posterior root avulsions of the lateral meniscus. This modified technique is designed to prevent tunnel convergence during a concomitant or staging of an anterior cruciate ligament (ACL) reconstruction. Promising short-term clinical outcomes were seen at the two-year follow-up for both patients. On second-look arthroscopy, one patient also demonstrated excellent healing. Conclusion: Results provide preliminary evidence suggesting that this technique may (1) facilitate anatomic healing of the root and (2) allow for concomitant or staged ACL reconstruction tunnel reaming.

Background: Meniscal root tears present in many forms and can have profound consequences on the health of knee articular cartilage. While the biomechanics, natural history, and treatment of root tears have been increasingly investigated, the spectrum of meniscal root tear patterns observed during arthroscopic examination has yet to be defined and categorized. Purpose: To establish a classification system for meniscal root tears by reporting the morphology of meniscal root tears from a consecutive series of arthroscopic surgeries. It was hypothesized that meniscal root tears could be grouped into types by distinct tear patterns and that recognition of tear pattern would affect treatment choice. Study Design: Case series; Level of evidence, 4. Methods: All patients who underwent arthroscopic surgery from April 2010 to May 2014 by a single orthopaedic surgeon were included. After arthroscopic examination, data regarding the integrity of the meniscal roots were prospectively recorded in a data registry. Tear morphology and treatment received were subsequently extracted by 2 independent reviewers from operative notes and arthroscopic surgical photos. Results: A total of 71 meniscal root tears in 67 patients were grouped into tear types with similar tear morphologies. Meniscal root tear patterns were categorized into partial stable root tears (type 1; n = 5); complete radial tears within 9 mm of the bony root attachment (type 2; n = 48), further subclassified into types 2A, 2B, and 2C, located 0 to Conclusion: This study demonstrated that it was possible to establish a concise classification system to group patients with meniscal root tears by tear morphology. Treatments received varied across tear types.

Background: The current standard for treating complete tears of the anterior cruciate ligament (ACL) is reconstruction, which requires reaming a tibial tunnel. Based on recent anatomic and biomechanical studies, this reconstruction tunnel may cause injuries to the anterior meniscal root attachments. Purpose/Hypothesis: The purpose was to determine if injuries occurred to the anteromedial (AM) and anterolateral (AL) meniscal root attachments because of reaming a tibial reconstruction tunnel in the anatomic center of the ACL footprint. It was hypothesized that tibial tunnel reaming for ACL reconstruction would result in significant decreases in the attachment area and in ultimate failure strength for the AL root. Study Design: Controlled laboratory study. Methods: Twelve matched pairs of human cadaveric knees were tested. One knee from each pair remained intact, while the contralateral knee was reamed with a tibial tunnel for an anatomic ACL reconstruction. The attachment areas of the anterior meniscal roots were measured with a coordinate measuring device before and after tunnel reaming. The anterior meniscal roots were then pulled to failure with a dynamic tensile testing machine. Results: There was a significant mean decrease in the attachment area for the AL root (%Δ, 38%; 95% CI, 25-51) after ACL tunnel reaming compared with the intact state ( P = .003). The mean ultimate failure strength of the native AL root (mean, 610 N; 95% CI, 470-751) was significantly stronger ( P = .015) than that of the AL root with a reamed ACL reconstruction tunnel (mean, 506 N; 95% CI, 353-659). Tunnel reaming did not significantly affect the AM root attachment area or ultimate failure strength. Conclusion: Tibial tunnel reaming during anatomic single-bundle ACL reconstruction significantly decreased the AL meniscal root attachment area and ultimate failure strength. The AM root was not significantly affected by reaming of the ACL reconstruction tunnel. Future studies should investigate the clinical importance of these iatrogenic injuries to the AL root. Clinical Relevance: The ACL reconstruction tunnels reamed in the center of the ACL tibial footprint caused a significant decrease in the attachment area and ultimate strength of the AL meniscal root attachment. Clinically, repositioning guide pins placed in the lateral aspect of the ACL attachment before tibial tunnel reaming may minimize iatrogenic injuries to the AL meniscal root attachment.

Background: Recent emphasis has turned to reconstructing the posterior cruciate ligament (PCL) after injury. However, single-bundle PCL reconstruction of the anterolateral bundle may potentially injure the posterior meniscal roots. Purpose/Hypothesis: The purpose of this study was to determine if posterior meniscal root injuries occurred because of tunnel reaming for single-bundle PCL reconstruction. It was hypothesized that tibial tunnel reaming within the anterolateral bundle footprint during PCL reconstruction would result in clinically significant decreases in posteromedial (PM) root attachment areas and in ultimate failure strength for the PM root. Study Design: Controlled laboratory study. Methods: Testing was performed on 12 matched pairs of human cadaveric knees. For each pair of knees, one knee was left intact, while the contralateral knee was prepared with a tibial tunnel placed 5 mm anterior to the center of the tibial PCL attachment and within the previously described footprint of the anterolateral bundle of the PCL for single-bundle PCL reconstruction. The attachment areas of the posterior meniscal roots were measured with a coordinate measuring device before and after PCL tunnel reaming. The posterior meniscal roots were then pulled to failure with a dynamic tensile testing machine. Results: There was a significant mean decrease in the attachment area of the PM root (%Δ, 28%; 95% CI, 16-40) after PCL tunnel reaming compared with the intact state ( P = .005). The mean ultimate failure strength of the native PM root (mean, 440 N; 95% CI, 347-534) was also significantly stronger (mean, 40%; 95% CI, 18-61; P = .005) than that of the PM root after PCL tunnel reaming (mean, 243 N; 95% CI, 176-309). No changes were found for the posterolateral (PL) root after PCL tunnel reaming. Conclusion: Tibial tunnel reaming for single-bundle PCL reconstruction in the anterolateral bundle footprint significantly reduced the ultimate failure strength and attachment area of the PM meniscal root. The attachment area and ultimate failure strength of the PL root were unaffected by tunnel reaming. Clinical Relevance: Tibial tunnels reamed in the footprint of the anterolateral bundle during single-bundle PCL reconstruction can cause iatrogenic damage to the PM meniscal root attachment. Thus, tibial tunnels should strive to be reamed in the center of the entire tibial PCL attachment site during PCL reconstruction.

Complete radial meniscus tears have been reported to result in deleterious effects in the knee joint if left unrepaired. An emphasis on meniscal preservation is important in order to restore native meniscal function. In this case report, a complete radial tear of the medial meniscus midbody was repaired using a novel crisscross suture transtibial technique. This technique secured the anterior and posterior meniscal horns, which were released from their extruded and scarred position along the capsule, using crisscrossing sutures passed through two transtibial tunnels and secured over a bone bridge on the anterolateral tibia. In addition, the repair was supplemented with the injection of platelet-rich plasma and bone marrow aspirate concentrate to promote the healing of the meniscal tissue. Complete healing on second-look arthroscopy is presented, including in the previously unreported white–white meniscal zone. Case Report, Level IV.

This paper presents the first reported case of iatrogenic injury to the anterior medial meniscal root attachment following intramedullary nailing for a tibial shaft fracture. The patient experienced a closed right tibia–fibula fracture 7 years prior to presentation, which was treated with a reamed intramedullary nail. The nail was removed 3 years after the index surgery due to chronic anterior knee pain, which persisted following hardware removal. At presentation, the patient was diagnosed with an anterior horn medial meniscal root tear likely secondary to insertion of the intramedullary nail through the anatomic footprint of the anterior medial root. After undergoing a medial meniscus anterior horn root repair, the patient was asymptomatic and resumed normal activities. Case report, Level IV.

Meniscal root tears, less common than meniscal body tears and frequently unrecognized, are a subset of meniscal injuries that often result in significant knee joint disorders. The meniscus root attachment aids meniscal function by securing the meniscus in place and allowing for optimal shock-absorbing function in the knee. With root tears, meniscal extrusion often occurs, and the transmission of circumferential hoop stresses is impaired. This alters knee biomechanics and kinematics and significantly increases tibiofemoral contact pressure. In recent years, meniscal root tears, which by definition include direct avulsions off the tibial plateau or radial tears adjacent to the root itself, have attracted attention because of concerns that significant meniscal extrusion dramatically inhibits normal meniscal function, leading to a condition biomechanically similar to a total meniscectomy. Recent literature has highlighted the importance of early diagnosis and treatment; fortunately, these processes have been vastly improved by advances in magnetic resonance imaging and arthroscopy. This article presents a review of the clinically relevant anatomic, biomechanical, and functional descriptions of the meniscus root attachments, as well as current strategies for accurate diagnosis and treatment of common injuries to these meniscus root attachments.

Posterolateral knee injuries occur more commonly than in the past. These injuries most commonly occur concurrent with cruciate ligament tears. The main stabilizers of the posterolateral knee are the fibular collateral ligament, the popliteus tendon, and the popliteofibular ligament. These static stabilizers function to prevent increased varus, external rotation, and coupled posterolateral rotation of the knee. The most important clinical tests to diagnose posterolateral knee injuries are the varus stress test, posterolateral drawer, and dial tests. Varus stress radiographs are key objective means to diagnose these injuries. Anatomic- based reconstructions have been validated to restore stability and improve outcomes.

Background:The anterolateral meniscal root (ALMR) has been reported to intricately insert underneath the tibial insertion of the anterior cruciate ligament (ACL). Previous studies have begun to evaluate the relationship between the insertion areas and the risk of iatrogenic injuries; however, the overlap of the insertions has yet to be quantified in the sagittal and coronal planes.Purpose:To investigate the insertions of the human tibial ACL and ALMR using scanning electron microscopy (SEM) and to quantify the overlap of the ALMR insertion in the coronal and sagittal planes.Study Design:Descriptive laboratory study.Methods:Ten cadaveric knees were dissected to isolate the tibial ACL and ALMR insertions. Specimens were prepared and imaged in the coronal and sagittal planes. After imaging, fiber directions were examined to identify the insertions and used to calculate the percentage of the ACL that overlaps with the ALMR instead of inserting into bone.Results:Four-phase insertion fibers of the tibial ACL were identified directly medial to the ALMR insertion as they attached onto the tibial plateau. The mean percentage of ACL fibers overlapping the ALMR insertion instead of inserting into subchondral bone in the coronal and sagittal planes was 41.0% ± 8.9% and 53.9% ± 4.3%, respectively. The percentage of insertion overlap in the sagittal plane was significantly higher than in the coronal plane ( P = .02).Conclusion:This study is the first to quantify the ACL insertion overlap of the ALMR insertion in the coronal and sagittal planes, which supplements previous literature on the insertion area overlap and iatrogenic injuries of the ALMR insertion. Future studies should determine how much damage to the ALMR insertion is acceptable to properly restore ACL function without increasing the risk for tears of the ALMR.Clinical Relevance:Overlap of the insertion areas on the tibial plateau has been previously reported; however, the results of this study demonstrate significant overlap of the insertions superior to the insertion sites on the tibial plateau as well. These findings need to be considered when positioning for tibial tunnel creation in ACL reconstruction to avoid damage to the ALMR insertion.

Complete radial tears of the medial meniscus significantly decrease the meniscal tissue's ability to dissipate tibiofemoral loads and have been described as functionally similar to a total meniscectomy, predisposing patients to early osteoarthritis. At present, no consensus exists regarding the optimal surgical treatment of a radial meniscal tear. Current repair techniques have led to a reportedly high rate of incomplete healing or healing of the meniscus in a nonanatomic, gapped position, which compromises its ability to withstand hoop stresses. Improvement regarding the ability to repair and heal medial meniscus radial tears has the potential to result in enhanced preservation of the articular cartilage in the medial compartment of the knee. This technical description details a method for repairing radial tears of the medial meniscus using a transtibial 2-tunnel technique.

Background: Metal screws are traditionally used to fix the coracoid process to the glenoid. Despite stable fixation, metal screws have been associated with hardware complications. Therefore, some studies have advocated for suture button fixation during the Latarjet procedure to reduce the complications associated with screw fixation. Purpose: To biomechanically evaluate the ultimate failure load of a cortical button and self-tensioning suture versus metal screws for coracoid graft fixation during the Latarjet procedure. Study Design: Controlled laboratory study. Methods: Eight matched pairs of fresh-frozen, male cadaveric shoulders (N = 16) underwent the Latarjet procedure. The shoulders of each pair were randomly assigned to 1 of 2 groups: fixation using two 3.75-mm cannulated, fully threaded metal screws or fixation using a double suture button construct. Specimens were secured in a dynamic testing machine and cyclically preconditioned from 2 to 10 N at 0.1 Hz for 10 cycles. After preconditioning, specimens were pulled to failure at a normalized displacement rate of 400% of the measured gauge length per minute. The ultimate failure load and mechanism of failure were recorded for each specimen. Results: The mean ultimate load to failure for screw fixation (226 ± 114 N; 95% CI, 147-305 N) was not significantly different from that for suture button fixation (266 ± 73 N; 95% CI, 216-317 N) ( P = .257). The mean strain at failure for screw fixation (63% ± 21%; 95% CI, 48%-77%) was not significantly different from that for suture button fixation (86% ± 26%; 95% CI, 69%-104%) ( P = .060). The most common mechanism of failure for the screw fixation method was at the bone block drill holes, while an intramuscular rupture at the clamp-muscle interface occurred for the suture button construct. Conclusion: The screw and suture button fixation techniques exhibited comparable biomechanical strength for coracoid bone block fixation of the Latarjet procedure. Clinical Relevance: Metal screws have been reported to be a large contributor to intraoperative and postoperative complications. Therefore, given the results of the current study, a suture button construct may be an alternative to metal screw fixation during the Latarjet procedure. However, further clinical studies are warranted.

Background The purpose of this study was to quantify the meniscal root anatomy of the New Zealand white rabbit to better understand this animal model for future in vitro and in vivo joint degeneration studies. Methods Ten non-paired fresh frozen New Zealand white rabbit knee stifle joints were carefully disarticulated for this study. Measurements were made for all bony landmarks and ligamentous structure attachment sites on the tibial plateau. The following soft tissue structures were consistently identified in the rabbit stifle joint: the anterior root attachment of the lateral meniscus, the anterior root attachment of the medial meniscus, the anterior cruciate ligament, the posterior root attachment of the medial meniscus, the ligament of Wrisberg, the posterior cruciate ligament, and the posterior meniscotibial ligament. The following bony landmarks were consistently identified: the extensor digitorum longus groove, the medial tibial eminence, the center of the tibial tuberosity, and the lateral tibial eminence. Results The center of the anterior cruciate ligament and the medial tibial eminence apex were found to be 3.4 ± 0.3 mm (2.9–3.6) and 6.1 ± 0.6 mm (5.1–7.0) respectively from the center of the medical anterior root attachment. The center of the anterior cruciate ligament and the lateral tibial eminence apex were found to be 2.1 ± 0.5 mm (1.2–2.7) and 7.0 ± 0.6 mm (6.4–8.2) respectively from the center of the lateral anterior root attachment. The center of the posterior cruciate ligament and the medial tibial eminence apex were found to be 2.0 ± 0.7 mm (0.5–2.6) and 1.8 ± 0.4 mm (1.2–2.4) respectively from the center of the medial posterior root attachment. Conclusions This study augments our understanding of the comparative anatomy of the rabbit stifle joint. This information will be useful for future biomechanical, surgical, and in vitro studies utilizing the rabbit stifle as a model for human knee joint degenerative diseases.

Background: Complete radial tears of the medial meniscus have been reported to be functionally similar to a total meniscectomy. At present, there is no consensus on an ideal technique for repair of radial midbody tears of the medial meniscus. Prior attempts at repair with double horizontal mattress suture techniques have led to a reportedly high rate of incomplete healing or healing in a nonanatomic (gapped) position, which compromises the ability of the meniscus to withstand hoop stresses. Hypothesis: A newly proposed 2-tunnel radial meniscal repair method will result in decreased gapping and increased ultimate failure loads compared with the double horizontal mattress suture repair technique under cyclic loading. Study Design: Controlled laboratory study. Methods: Ten matched pairs of male human cadaveric knees (average age, 58.6 years; range, 48-66 years) were used. A complete radial medial meniscal tear was made at the junction of the posterior one-third and middle third of the meniscus. One knee underwent a horizontal mattress inside-out repair, while the contralateral knee underwent a radial meniscal repair entailing the same technique with a concurrent novel 2-tunnel repair. Specimens were potted and mounted on a universal testing machine. Each specimen was cyclically loaded 1000 times with loads between 5 and 20 N before experiencing a load to failure. Gap distances at the tear site and failure load were measured. Results: The 2-tunnel repairs exhibited a significantly stronger ultimate failure load (median, 196 N; range, 163-212 N) than did the double horizontal mattress suture repairs (median, 106 N; range, 63-229 N) ( P = .004). In addition, the 2-tunnel repairs demonstrated decreased gapping at all testing states ( P < .05) with a final measured gapping of 1.7 mm and 4.1 mm after 1000 cycles for the 2-tunnel and double horizontal mattress suture repairs, respectively. Conclusion: The 2-tunnel repairs displayed significantly less gapping distance after cyclic loading and had significantly stronger ultimate failure loads compared with the double horizontal mattress suture repairs. Clinical Relevance: Complete radial tears of the medial meniscus significantly decrease the ability of the meniscus to dissipate tibiofemoral loads, predisposing patients to early osteoarthritis. Improving the ability to repair medial meniscal radial tears in a way that withstands cyclic loads and heals in an anatomic position could significantly improve patient healing rates and result in improved preservation of the articular cartilage of the medial compartment of the knee. The 2-tunnel repair may be a more reliable and stronger repair option for midbody radial tears of the medial meniscus. Clinical studies are warranted to further evaluate these repairs.

Meniscal tears differ in terms of pattern and location. If left untreated, a meniscal tear can lead to the development of osteoarthritis and increased pain, swelling, and functional limitations. Tears in the vascularized outer two-thirds of the meniscus can often be successfully repaired with use of an inside-out technique. Vertical mattress sutures stabilize the meniscal tear in place, allowing for proper healing. The principal steps in the procedure include (1) assessing the location and pattern of the tear arthroscopically, (2) performing a medial or lateral meniscal repair incision in the proper anatomic location, (3) passing the sutures in a vertical mattress pattern through the torn meniscus, and (4) tying the sutures while verifying sufficient reduction of the tear arthroscopically. Postoperatively, patients remain non-weight-bearing for the course of six weeks. Passive knee flexion from 0° to 90° is allowed for the first two weeks. After two weeks, motion is increased as tolerated. At six weeks postoperatively, patients are allowed to progress to weight-bearing as tolerated and initiate the use of a stationary bicycle. They should avoid squatting, sitting cross-legged, and squatting and lifting for four months postoperatively to avoid substantial stress on the healing meniscus. After four months, sports-specific activities are initiated. Patients are expected to return to normal physical activity within four to six months postoperatively.

Background: Intramedullary (IM) nailing is the treatment of choice among orthopaedic surgeons for tibial shaft fractures. However, because of the close proximity of the nail’s insertion site to the anterior medial (AM) meniscal root on the tibial plateau, there is increased risk of iatrogenic injury to the meniscal root during nailing. Purpose: To quantify the area of the AM meniscal root footprint damaged by IM tibial reaming and determine its subsequent effects on the ultimate failure load in female versus male knees. Study Design: Controlled laboratory study. Methods: Twelve matched pairs (6 male and 6 female pairs; average age, 50.2 years) of human cadaveric knees were randomly assigned to native and reamed groups. In the reamed group, knees were reamed within the “safe zone” according to current guidelines for IM tibial nail insertion (3 mm lateral to the center of the tibial tubercle and adjacent to the anterior margin of the tibial plateau). The attachment areas and ultimate failure load were quantified and compared with paired knees in the native group. Results: Intra-articular reaming within the “safe zone” for IM tibial nail insertion did not significantly decrease the AM root attachment area or ultimate failure load in male specimens, as only 2 of the 6 knees were damaged by reaming. In contrast, all 6 of the AM roots in the female knees were damaged by reaming, and on average, reaming decreased the female AM root attachment area by 19% and significantly decreased ultimate failure load by 37% ( P = .028). There was a strong negative correlation ( R2 = 0.77) between reamed tunnel–AM root overlap area and medial-lateral width in female but not in male knees. Conclusion: Standard reaming for an IM tibial nail induced significant damage to the AM meniscal root in smaller, female specimens, whereas larger, male specimens were not affected. Clinical Relevance: These findings may suggest that improvements in current guidelines and surgical techniques are warranted to prevent iatrogenic injury to the AM meniscal root during intramedullary reaming for tibial shaft fractures in females and in smaller patients.

Background: Posterior medial meniscal root tears have been reported to extrude with the meniscus becoming adhered posteromedially along the posterior capsule. While anatomic repair has been reported to restore tibiofemoral contact mechanics, it is unknown whether nonanatomic positioning of a meniscal root repair to a posteromedial location would restore the loading profile of the knee joint. Purpose/Hypothesis: The purpose of this study was to compare the tibiofemoral contact mechanics of a nonanatomic posterior medial meniscal tear with that of the intact knee or anatomic repair. It was hypothesized that a nonanatomic root repair would not restore the tibiofemoral contact pressures and areas to that of the intact or anatomic repair state. Study Design: Controlled laboratory study. Methods: Tibiofemoral contact mechanics were recorded in 6 male human cadaveric knee specimens (average age, 45.8 years) using pressure sensors. Each knee underwent 5 testing conditions for the posterior medial meniscal root: (1) intact knee; (2) root tear; (3) anatomic transtibial pull-out repair; (4) nonanatomic transtibial pull-out repair, placed 5 mm posteromedially along the edge of the articular cartilage; and (5) root tear concomitant with an ACL tear. Knees were loaded with a 1000-N axial compressive force at 4 flexion angles (0°, 30°, 60°, 90°), and contact area, mean contact pressure, and peak contact pressure were calculated. Results: Contact area was significantly lower after nonanatomic repair than for the intact knee at all flexion angles (mean = 44% reduction) and significantly higher for anatomic versus nonanatomic repair at all flexion angles (mean = 27% increase). At 0° and 90°, and when averaged across flexion angles, the nonanatomic repair significantly increased mean contact pressures in comparison to the intact knee or anatomic repair. When averaged across flexion angles, the peak contact pressures after nonanatomic repair were significantly higher than the intact knee but not the anatomic repair. In contrast, when averaged across all flexion angles, the anatomic repair resulted in a 17% reduction in contact area and corresponding increases in mean and peak contact pressures of 13% and 26%, respectively, compared with the intact knee. Conclusion: For most testing conditions, the nonanatomic repair did not restore the contact area or mean contact pressures to that of the intact knee or anatomic repair. However, the anatomic repair produced near-intact contact area and resulted in relatively minimal increases in mean and peak contact pressures compared with the intact knee. Clinical Relevance: Results emphasize the importance of ensuring an anatomic posterior medial meniscal root repair by releasing the extruded menisci from adhesions and the posteromedial capsule. Similar caution toward preventing displacement of the meniscal root repair construct should be emphasized.

Posterior root avulsions of the medial and lateral menisci result in decreased areas of tibiofemoral contact and increased tibiofemoral contact pressures. These avulsions may lead to the development of osteoarthritis. Therefore, two surgical techniques, the transtibial pullout repair and the suture anchor repair, have recently been developed to restore the native structure and function of the meniscal root attachment. Compared with the historical alternative of partial or total meniscectomy, these techniques allow for meniscal preservation and anatomic reduction of the meniscal roots, with the goal of preventing the development and progression of osteoarthritis. However, early biomechanical and clinical studies have reported conflicting results on the effectiveness of both techniques with regard to resisting displacement and facilitating healing. Although there is currently a lack of consensus on which is the superior technique, transtibial pullout and suture anchor repairs are increasingly used in clinical practice.

Background: Current methods of the transtibial pull-out meniscal root repair significantly displace under cyclic loading in porcine models but have not been evaluated in human models. One potential explanation for the displacement is that a single transtibial tunnel may not fully restore the attachment of the entire posterior medial meniscal root. Purpose/Hypothesis: The purpose of this study was to biomechanically evaluate the transtibial pull-out technique in a human cadaveric model using either 1 or 2 transtibial bone tunnels. The hypothesis was that a transtibial pull-out technique using 2 transtibial bone tunnels would confer superior biomechanical properties in comparison to an iteration using 1 transtibial bone tunnel. Study Design: Controlled laboratory study. Methods: Ten matched pairs of male human cadaveric knees (average age, 52.7 years) were randomly assigned (1 each of the pair) to 2 groups consisting of a transtibial pull-out technique using either 1 or 2 transtibial bone tunnels. The knees were cyclically loaded for 1000 cycles from 10 to 30 N at 0.5 Hz, representing the loads experienced during a typical meniscal root repair postoperative rehabilitation program, and then pulled to failure at a rate of 0.5 mm/s. Results: Differences between 1- and 2-tunnel repair groups were neither statistically nor clinically significant with respect to displacement or ultimate failure load. On average, the 1- and 2-tunnel repair groups resulted in 3.32 mm and 3.23 mm of displacement, respectively, after 1000 testing cycles. At 1, 100, 500, and 1000 testing cycles, displacement was not significantly different between groups ( P > .799). The 2-tunnel repair technique resulted in a 10.2% higher ultimate failure load (135 N vs 123 N); however, this was not significant ( P = .333). Conclusions: Similar biomechanical properties were seen between transtibial pull-out repairs using either 1 or 2 transtibial bone tunnels in a human cadaveric model. Both repair groups exceeded the 3-mm threshold for nonanatomic displacement. Clinical Relevance: This study indicates that a newly proposed iteration of the transtibial pull-out repair technique using a second transtibial tunnel, which theoretically restores more of the posterior medial meniscal root, was almost identical to the current clinical standard involving a single transtibial tunnel. As the importance of repairing meniscal root tears is increasingly recognized, further studies on new iterations of both techniques are warranted to minimize the risk of displacement caused by early motion in the initial postoperative rehabilitation period.

Injuries to the posterolateral and posteromedial corners of the knee are common and represent a significant diagnostic and treatment challenge. A thorough understanding of posterolateral and posteromedial knee anatomy and biomechanics is paramount for accurate diagnosis and treatment of patients with medial and lateral knee injuries. In the posterolateral corner (PLC) of the knee, the primary static stabilizers include the fibular (lateral) collateral ligament (FCL), popliteus tendon (PLT), and popliteofibular ligament (PFL). Together, these structures function to resist varus gapping and angulation, external rotation, internal rotation, and anterior translation. In the posteromedial knee, the primary structures include the superficial medial collateral ligament (sMCL), deep medial collateral ligament (dMCL), and posterior oblique ligament (POL). These structures function to resist valgus gapping, internal rotation, and external rotation. The purpose of this chapter is to highlight recent advances in the understanding of posterolateral and posteromedial corner anatomy and biomechanics and their surgical implications.

Background: A common treatment for posterior meniscal root tears is transtibial pull-out repair, which has been biomechanically reported to restore tibiofemoral contact mechanics to those of the intact knee. Biomechanical data suggest that there is significant displacement of the repaired meniscal root with cyclic loading, which may be responsible for the poor healing and meniscal extrusion demonstrated in some clinical studies. Hypothesis/Purpose: The purpose of this study was to quantify the time-zero displacement of the posterior meniscal root in response to cyclic loading after transtibial pull-out repair and to quantify the individual contributions to displacement of the following: (1) suture elongation, (2) button-bone interface, and (3) meniscus-suture interface. The meniscus-suture interface was hypothesized to result in significantly more displacement than the button-bone interface or suture elongation. Study Design: Descriptive laboratory study. Methods: Transtibial pull-out repair of the posterior medial meniscal root was performed in 6 porcine knees, and cyclic displacement was measured using a loading protocol representative of postoperative rehabilitation. Displacement from (1) suture elongation, (2) the button-bone interface, and (3) the meniscus-suture interface was determined by cyclically loading 6 specimens for each construct using the same loading protocol to determine the contribution of each component to the overall displacement of the repair construct. Results: After 1000 cycles, the repair construct displaced by a mean of 3.28 mm (95% CI, 2.07-4.49). The meniscus-suture component (mean, 2.52 mm; 95% CI, 2.21-2.83) displaced significantly more than the button-bone component (mean, 0.90 mm; 95% CI, 0.64-1.15; P = .006) and suture elongation component (mean, 0.71 mm; 95% CI, 0.36-1.06; P = .006) after 1000 cycles. Displacement of the button-bone and suture elongation components was not significantly different after 1000 cycles ( P = .720). Conclusion: There was substantial displacement of the posterior medial meniscal root repaired with the transtibial pull-out technique under a cyclic loading protocol simulating postoperative rehabilitation. The meniscus-suture interface contributed to significantly more displacement than the button-bone interface and suture elongation in the transtibial pull-out repair construct. Clinical Relevance: The results provide a framework for optimizing the transtibial pull-out repair technique. Future studies should focus on improving suture fixation strength within the meniscus-suture interface.

Background: Anatomic root placement is necessary to restore native meniscal function during meniscal root repair. Radiographic guidelines for anatomic root placement are essential to improve the accuracy and consistency of anatomic root repair and to optimize outcomes after surgery. Purpose: To define quantitative radiographic guidelines for identification of the anterior and posterior root attachments of the medial and lateral menisci on anteroposterior (AP) and lateral radiographic views. Study Design: Descriptive laboratory study. Methods: The anterior and posterior roots of the medial and lateral menisci were identified in 12 human cadaveric specimens (average age, 51.3 years; age range, 39-65 years) and labeled using 2-mm radiopaque spheres. True AP and lateral radiographs were obtained, and 2 raters independently measured blinded radiographs in relation to pertinent landmarks and radiographic reference lines. Results: On AP radiographs, the anteromedial and posteromedial roots were, on average, 31.9 ± 5.0 mm and 36.3 ± 3.5 mm lateral to the edge of the medial tibial plateau, respectively. The anterolateral and posterolateral roots were, on average, 37.9 ± 5.2 mm and 39.3 ± 3.8 mm medial to the edge of the lateral tibial plateau, respectively. On lateral radiographs, the anteromedial and anterolateral roots were, on average, 4.8 ± 3.7 mm and 20.5 ± 4.3 mm posterior to the anterior margin of the tibial plateau, respectively. The posteromedial and posterolateral roots were, on average, 18.0 ± 2.8 mm and 19.8 ± 3.5 mm anterior to the posterior margin of the tibial plateau, respectively. The intrarater and interrater intraclass correlation coefficients (ICCs) were >0.958, demonstrating excellent reliability. Conclusion: The meniscal root attachment sites were quantitatively and reproducibly defined with respect to anatomic landmarks and superimposed radiographic reference lines. The high ICCs indicate that the measured radiographic relationships are a consistent means for evaluating meniscal root positions. Clinical Relevance: This study demonstrated consistent and reproducible radiographic guidelines for the location of the meniscal roots. These measurements may be used to assess root positions on intraoperative fluoroscopy and postoperative radiographs.

Background: While the biomechanical importance of the meniscal roots has been demonstrated, the anatomy of the anterior meniscal roots remains largely unknown. Defining the quantitative anatomy of the anterior meniscal root attachments is essential for developing improved diagnostic and surgical techniques. Hypothesis: The anterior medial (AM) and anterior lateral (AL) meniscal roots could be quantitatively defined relative to open and arthroscopic surgical landmarks. Study Design: Descriptive laboratory study. Methods: Twelve nonpaired human cadaveric knees were used (average age, 51.3 years). A coordinate measuring device quantified the anatomic relationships of the AM and AL root attachments to open and arthroscopic surgical landmarks. The tibial attachments of both anterior roots were defined and quantified by categorizing the fibers of the root as either central, dense attachments or peripheral, supplemental attachments. Results: The center of the tibial tuberosity and the medial tibial eminence apex were 27.0 mm lateral and distal and 27.5 mm posterior to the center of the AM root, respectively. The center of the anterior cruciate ligament (ACL) and the lateral tibial eminence apex were 5.0 mm posteromedial and 14.4 mm posterolateral to the center of the AL root, respectively. The AM root attachment had a mean area of 110.4 mm2 (95% CI, 92.2-128.5) with a central attachment of 56.3 mm2 (95% CI, 46.9-65.8). The AL root attachment had a mean area of 140.7 mm2 (95% CI, 121.6-159.8) and inserted deeply beneath the ACL in all specimens. The overlap of the ACL on the AL root averaged 88.9 mm2 (95% CI, 63.3-114.6), comprising 63.2% of the AL root attachment. Conclusion: The anterior meniscal roots were identified in relation to pertinent open and arthroscopic landmarks. The extended overlap between the AL root and ACL attachment revealed a more intimate tibial attachment relationship than previously recognized. Clinical Relevance: Quantitative descriptions of the anterior meniscal roots elucidate the relationship between the root attachments and pertinent surgical landmarks. In addition, the supplemental attachments of both menisci may contribute to native meniscal function, and further investigation is recommended.

The posterior lateral (PL) meniscal root plays an essential role in ensuring the health of the articular cartilage of the knee joint. Injuring the PL meniscal root has been demonstrated to result in significant deleterious changes to tibiofemoral contact mechanics. Anatomic studies have reported that the posterolateral bundle of the anterior cruciate ligament (ACL) and PL root lie in close proximity on the tibial plateau. Therefore, during a double-bundle ACL reconstruction, the PL root may be inadvertently injured during the reaming of the posterior ACL double-bundle reconstruction tibial tunnel that is intended to recreate the posterolateral bundle of the ACL. This case report describes an occurrence of iatrogenic injury to the PL root due to a posteriorly malpositioned double-bundle ACL tibial tunnel. This report is the first known description of this mechanism of injury in the literature. Case report, Level IV.

Background: Current surgical techniques for meniscal root repair reattach the most prominent, dense portion of the meniscal root and fail to incorporate recently identified peripheral, supplemental attachment fibers. The contribution of supplemental fibers to the biomechanical properties of native meniscal roots is unknown. Hypothesis/Purpose: The purpose was to quantify the ultimate failure strengths, stiffness, and attachment areas of the native posterior medial (PM), posterior lateral (PL), anterior medial (AM), and anterior lateral (AL) meniscal roots compared with the most prominent, dense meniscal root attachment after sectioning of supplemental fibers. It was hypothesized that the ultimate failure strength, stiffness, and attachment area of each native root would be significantly higher than those of the respective sectioned root. Study Design: Controlled laboratory study. Methods: Twelve matched pairs of male human cadaveric knees were used. The 4 native meniscal roots were left intact in the native group, whereas the roots in the contralateral knee (sectioned group) were dissected free of all supplemental fibers. A coordinate measuring device quantified the amount of tissue resected in the sectioned group compared with the native group. A dynamic tensile testing machine pulled each root in line with its circumferential fibers. All root attachments were preconditioned from 10 to 50 N at a rate of 0.1 Hz for 10 cycles and subsequently pulled to failure at a rate of 0.5 mm/s. Results: Supplemental fibers composed a significant percentage of the native PM, PL, and AM meniscal root attachment areas. Mean ultimate failure strengths (in newtons) of the native PM, PL, and AM roots were significantly higher than those of the sectioned state, while the ultimate failure strength of the native AL root was indistinguishable from that of the sectioned state. Conclusion: Three of the 4 meniscal root attachments (PM, PL, AM) contained supplemental fibers that accounted for a significant percentage of the native root attachment areas, and these fibers significantly contributed to the failure strengths of the native roots. Clinical Relevance: These supplemental fibers are not routinely reattached during root repair surgery, suggesting that current techniques fail to reattach the biomechanically relevant attachments of native meniscal roots.

The purpose of this study was to determine the diagnostic accuracy of 3 T MRI, including sensitivity, specificity, negative and positive predictive values, for detection of posterior medial and lateral meniscus root tears and avulsions. All patients who had a 3 T MRI of the knee, followed by arthroscopic surgery, were included in this study. Arthroscopy was considered the gold standard. Meniscus root tears diagnosed at arthroscopy and on MRI were defined as a complete meniscus root detachment within 9 mm of the root. All surgical data were collected prospectively and stored in a data registry. MRI exams were reported prospectively by a musculoskeletal radiologist and reviewed retrospectively. There were 287 consecutive patients (156 males, 131 females; mean age 41.7 years) in this study. Prevalence of meniscus posterior root tears identified at arthroscopy was 9.1, 5.9 % for medial and 3.5 % for lateral root tears (one patient had both). Sensitivity was 0.770 (95 % CI 0.570, 0.901), specificity was 0.729 (95 % CI 0.708, 0.741), positive predictive value was 0.220 (95 % CI 0.163, 0.257) and negative predictive value was 0.970 (95 % CI 0.943, 0.987). For medial root tears, sensitivity was 0.824 (95 % CI 0.569, 0.953), specificity was 0.800 (95 % CI 0.784, 0.808), positive predictive value was 0.206 (95 % CI 0.142, 0.238) and negative predictive value was 0.986 (95 % CI 0.967, 0.996). For lateral meniscus posterior root tears, sensitivity was 0.600 (95 % CI 0.281, 0.860), specificity was 0.903 (95 % CI 0.891, 0.912), positive predictive value was 0.181 (95 % CI 0.085, 0.261) and negative predictive value was 0.984 (95 % CI 0.972, 0.994). This study demonstrated moderate sensitivity and specificity of 3 T MRI to detect posterior meniscus root tears. The negative predictive value of 3 T MRI to detect posterior meniscus root tears was high; however, the positive predictive value was low. Sensitivity was higher for medial root tears, indicating a higher risk of missing lateral root tears on MRI. Imaging has an important role in identifying meniscus posterior horn root tears; however, some root tears may not be identified until arthroscopy. Prognostic study (diagnostic), Level II.

Background An avulsion of the posterior root attachment of the lateral meniscus or a radial tear close to the root attachment can lead to degenerative knee arthritis. Although the biomechanical effects of comparable injuries involving the medial meniscus have been studied, we are aware of no such study involving the lateral meniscus. We hypothesized that in situ pull-out suture repair of lateral meniscus root avulsions and of complete radial tears 3 and 6 mm from the root attachment would increase the contact area and decrease mean and peak tibiofemoral contact pressures, at all knee flexion angles, relative to the corresponding avulsion or tear condition. Methods Eight human cadaveric knees underwent biomechanical testing. Eight lateral meniscus conditions (intact, footprint tear, root avulsion, root avulsion repair, radial tears at 3 and 6 mm from the posterior root, and repairs of the 3 and 6-mm tears) were tested at five different flexion angles (0°, 30°, 45°, 60°, and 90°) under a compressive 1000-N load. Results Avulsion of the posterior root of the lateral meniscus or an adjacent radial tear resulted in significantly decreased contact area and increased mean and peak contact pressures in the lateral compartment, relative to the intact condition, in all cases except the root avulsion condition at 0° of flexion. In situ pull-out suture repair of the root avulsion or radial tear significantly reduced mean contact pressures, relative to the corresponding avulsion or tear condition, when the results for each condition were pooled across all flexion angles. Conclusions Posterior horn root avulsions and radial tears adjacent to the root attachment of the lateral meniscus significantly increased contact pressures in the lateral compartment. In situ pull-out suture repairs of these tears significantly improved lateral compartment joint contact pressures. Clinical relevance In situ repair may be an effective treatment to improve tibiofemoral contact profiles after an avulsion of the posterior root of the lateral meniscus or a complete radial tear adjacent to the root. In situ repairs should be further investigated clinically as an alternative to partial lateral meniscectomy.

The meniscal roots are essential for preserving the native biomechanical and structural properties of the tibiofemoral joint. Meniscus root avulsions, which disrupt the normal meniscus anchoring points, have been reported to result in deleterious biomechanics and clinical outcomes. In this series, two cases of iatrogenic medial meniscus anterior root avulsions after anterior cruciate ligament (ACL) reconstruction are reported. Iatrogenic medial meniscus anterior root avulsions after malpositioning of the tibial tunnels during ACL reconstruction have not been previously reported in the literature and may account for poor long-term outcomes seen in some patients after ACL reconstruction. Therefore, careful attention must be paid to correct tibial tunnel placement during ACL reconstruction.Case series, Level IV.

To determine whether reaming of anterior cruciate ligament (ACL) reconstruction tibial tunnels with a 10-mm-diameter reamer would result in injury to the anterior roots of the medial and lateral menisci in an in vitro model when using a tibial aiming device at two settings (40° and 60°).Three-dimensional footprints of the ACL and the anterior roots of the menisci were measured for 12 human cadaveric tibias. Measurements were taken before and after attempted reaming of an ACL tibial reconstruction tunnel in the calculated ACL centre using a tibial aiming device set at two angles (40° and 60°).Iatrogenic injury to the anterior root of the medial meniscus caused by overlap with the reamed tibial tunnel was found in 3/6 specimens in Group 1 (40°) and 0/6 specimens in Group 2 (60°). The average area of iatrogenic injury in Group 1 was 9.6 mm(2) (8.6 % of the root). There was iatrogenic injury to the anterior root of the lateral meniscus in 4/6 specimens for both groups. The average area of iatrogenic injury was 20.5 mm(2) (28.8 %) for Group 1 and 16.2 mm(2) (25.9 %) for Group 2.Reaming of ACL tibial reconstruction tunnels carries a risk of iatrogenic injury to the anterior meniscus roots, even when tunnels are reamed based on guide pin placement in the calculated centre of the ACL. Reaming at varying tibial aiming device angle settings can affect the obliquity of the tunnel aperture and cause iatrogenic injury to the anterior meniscal roots. Caution should be exercised clinically to avoid iatrogenic injury to both the anterior meniscal roots while reaming tibial tunnels during ACL reconstructions.

The patellofemoral joint is a very intricate and essential joint for the athlete, and the knowledge about the anatomy of the joint continues to progress. Numerous muscles, bones, ligaments, tendons, bursa sacs, arteries, and nerves contribute to the functionality of the joint and allow athletes to perform at the highest level by establishing knee stability and preventing pain. However, patellofemoral joint pathology continues to be a common problem associated with athletics, and knowledge about the anatomy is critical in order to diagnose and treat injuries as quickly as possible so that athletes can return to competition in the shortest possible time frame. This chapter focuses on the relevant surgical anatomy for the numerous structures in the patellofemoral joint by combining a summary of the relevant and available literature, along with numerous illustrations, to provide a synopsis of current knowledge about patellofemoral knee joint anatomy.

Meniscal root tears are substantial injuries that usually require surgical management. If left untreated, meniscal root tears can lead to the rapid onset of osteoarthritis similar to that seen after a total meniscectomy. Meniscal root tears often go unnoticed on magnetic resonance imaging and arthroscopy, in large part because meniscal root anatomy and its biomechanical importance have been defined only recently. In a transtibial meniscal root repair, the current clinical standard of care, the root is reattached to its native attachment site on the tibial plateau, restoring tibiofemoral contact mechanics. While this video article shows a posterior medial root repair technique, the same anatomic, biomechanical, and surgical principles apply to a posterior lateral meniscal root attachment. The principal steps in this procedure include (1) verifying the presence of a posterior medial meniscal root tear with arthroscopic visualization and probing, (2) inspecting the root tear and debriding the root attachment site to bone with a curet, (3) arthroscopic release of any adhesions that cause retraction of the meniscal root to a nonanatomic position, (4) drilling of two separate transtibial tunnels that extend down to the anteromedial portion of the tibia, (5) placing an accessory portal to pass the sutures, (6) placing two simple sutures through the torn meniscal root and shuttling them down the tibial tunnels, and (7) tying the sutures over a surgical button on the anteroproximal portion of the tibia with the knee flexed 90°. Postoperatively, patients remain non-weight-bearing for six weeks. Passive knee flexion from 0° to 90° is allowed for the first two weeks. After two weeks, motion is increased as tolerated. Patients initiate weight-bearing at postoperative week six and commence the use of a stationary bicycle. Resistive exercises are slowly progressed, and the patient should avoid squatting as well as squatting and lifting for four months. Patients are expected to return to normal physical activity within four to six months postoperatively.

In recent years, the use of biologics for the primary treatment and augmentation of treatment in patients with knee pathology has increased substantially. Techniques and applications for biologic preparations such as platelet-rich plasma (PRP) and mesenchymal stem cells (MSCs) have been developed and refined to increase the healing response in bone, ligaments, cartilage, meniscal tissue, and other areas of the knee. Beginning with basic science and animal models, and finally proceeding to clinical human trials, the effect of biologics on clinical outcomes has been widely studied; however, many results have been inconclusive on their true effectiveness. The purpose of this article is to review current strategies for evaluating outcomes after biologic treatment and to propose new recommendations for assessing outcomes following the use of biologics in the knee. In addition, the importance of study design, current challenges, and future directions will be reviewed to describe the current standards for future studies to follow.