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Background: Matrix-induced autologous chondrocyte implantation (MACI) is an established cell-based therapy for the treatment of chondral defects of the knee. As long-term outcomes are now being reported in the literature, it is important to systematically review available evidence to better inform clinical practice. Purpose: To report (1) subjective patient-reported outcomes (PROs) and (2) the rate of graft failure, reoperation, and progression to total knee arthroplasty (TKA) after undergoing MACI of the knee at a minimum 10-year follow-up. Study Design: Systematic review; Level of evidence, 4. Methods: A comprehensive search of Ovid MEDLINE and Epub Ahead of Print, In-Process & Other Non-Indexed Citations and Daily; Ovid Embase; Ovid Cochrane Central Register of Controlled Trials; Ovid Cochrane Database of Systematic Reviews; and Scopus from 2008 to September 15, 2022, was conducted in the English language. Study eligibility criteria included (1) full-text articles in the English language, (2) patients undergoing a MACI within the knee, (3) clinical outcomes reported, and (4) a minimum 10-year follow-up. Results: In total, 168 patients (99 male, 69 female; mean age, 37 years [range, 15-63 years]; mean body mass index, 26.2 [range, 18.6-39.4]) representing 188 treated chondral defects at a minimum 10-year follow-up after MACI were included in this review. Significant and durable long-term improvements were observed across multiple PRO measures. Follow-up magnetic resonance imaging (MRI), when performed, also demonstrated satisfactory defect fill and an intact graft in the majority of patients. The all-cause reoperation rate was 9.0%, with an overall 7.4% rate of progression to TKA at 10 to 17 years of follow-up. Conclusion: At a minimum 10-year follow-up, patients undergoing MACI for knee chondral defects demonstrated significant and durable improvements in PROs, satisfactory defect fill on MRI-based assessment, and low rates of reoperation and TKA. These data support the use of MACI as a long-term treatment of focal cartilage defects of the knee. [ABSTRACT FROM AUTHOR]

Background: Fresh-frozen allografts are the current standard in meniscal allograft transplant (MAT) surgery, due to their availability, ease of preservation, and affordability. However, fresh-frozen grafts are associated with several clinical challenges such as graft shrinkage and extrusion, among many others. Purpose: To present the current knowledge on the use of fresh meniscal allografts, presenting whether benefits associated with fresh grafts provide sufficient evidence to support their use in clinical practice. Study Design: Systematic review; Level of evidence, 5. Methods: A comprehensive search was conducted with keywords listed below. After an initial screening on title and abstract, full-text articles were assessed with the inclusion criteria. Results: A total of 78 studies matched the inclusion criteria. Literature and preclinical studies indicated that fresh meniscal allografts are beneficial for maintaining mechanical properties, graft ultrastructure, and matrix metabolism due to the presence of viable cells. Therefore, fresh allografts may address common complications associated with fresh-frozen MAT. To overcome challenges associated with both fresh-frozen and fresh allografts, a group has studied treating fresh-frozen allografts with a cell-based injection therapy. Conclusion: Fresh meniscal allografts pose several challenges including limited availability, demanding preservation procedures, and high costs. Although the role of viable cells within meniscal allografts remains controversial, these cells may be vital for maintaining tissue properties. [ABSTRACT FROM AUTHOR]

Background: Osteochondral allograft transplantation (OCAT) is an accepted knee joint–preserving treatment strategy for focal osteochondral lesions that is often conducted in combination with meniscal allograft transplantation (MAT). Despite its frequent and simultaneous utilization, there remains a lack in the literature reporting on outcomes and failure rates after concomitant procedures. Purpose: To determine (1) the midterm clinical success rate after OCAT+MAT in comparison with a matched-pair cohort undergoing isolated OCAT, (2) whether patient-specific and procedural variables influence the risk of failure, and (3) patient-reported outcome measures over time. Study Design: Cohort study; Level of evidence, 3. Methods: A single-center matched-pair cohort study was conducted investigating outcomes in patients who underwent OCAT of the medial or lateral femoral condyle with and without MAT between 2004 and 2020. Patients were matched 1:1 by age (±5 years), sex (male or female), body mass index (±5), and grouped Kellgren and Lawrence grade (grades 0-1 or 2-4). The minimum follow-up time was 2 years. Radiographic variables (International Cartilage Regeneration & Joint Preservation Society [ICRS] grade and Kellgren and Lawrence grade) were assessed preoperatively and at follow-up. Subjective patient-reported outcome measures (Lysholm score, Knee injury and Osteoarthritis Outcome Score [KOOS] including subscores, International Knee Documentation Committee [IKDC] score, and visual analog scale score) were collected preoperatively and at follow-up. Clinical failure was defined as revision surgery for graft failure or conversion to total knee arthroplasty. Patient-reported, clinical, and radiographic outcomes were compared between groups. Results: In total, 66 patients (33 treated with isolated OCAT, 33 treated with OCAT+MAT; 57.6% male) with a mean age of 26.3 years (range, 18-62 years) were followed for a mean of 5.6 years (minimum, 2 years; range, 24-218 months). The 2 cohorts showed no difference in Kellgren and Lawrence grade postoperatively (P =.59). There was a significantly higher ICRS grade detected at follow-up in the OCAT+MAT group (2.81 ± 1.10) compared with the OCAT group (2.04 ± 0.96) (P <.05). There were no statistically significant differences between the groups regarding reoperation rate (OCAT: n = 6; OCAT+MAT: n = 13; P =.116), time to reoperation (OCAT: 46.67 ± 47.27 months vs OCAT+MAT: 28.08 ± 30.16 months; P =.061), and failure rate (OCAT: n = 4 [12.1%] vs OCAT+MAT: n = 5 [15.2%]; P =.66). In the OCAT+MAT group, an increase of tibial slope by 1° conferred a 1.65-fold increase in the hazard for failure over decreased slope (hazard ratio, 1.65; 95% CI, 1.10-2.50; P <.05). The overall survival rate was 86% at a mean follow-up of 5.6 years. Patient-reported outcome scores were significantly improved at the final follow-up compared with preoperative status. No significant differences were seen between groups with respect to subjective IKDC, Lysholm, Tegner, and KOOS results, except for the KOOS Symptoms subscale score, which was significantly higher in the OCAT+MAT group than in the OCAT group (mean difference, 14.6; P <.05) and did exceed the minimal clinically important difference threshold of 10.7. Conclusion: Midterm results after isolated OCAT and OCAT+MAT show high rates of healing and sustainable subjective improvement of knee function and quality of life. However, it should be noted that the difference in reoperation rate and time to reoperation between the groups is arguably clinically important and that lack of statistical significance may be because of low power. These results imply that isolated OCAT is an efficient joint-preserving treatment that can be combined with MAT in well-selected patients with meniscal insufficiency without negative influence on global clinical outcomes. [ABSTRACT FROM AUTHOR]

Background: Meniscal allograft transplantation (MAT) is an accepted and effective treatment option in the context of unsalvageable menisci, particularly in young and active patients. It has been shown to reduce pain and improve knee function in previously symptomatic patients. However, there is still limited knowledge about the long-term survival rates of allografts, the durability of clinical results, and the influence of patient-specific parameters, such as leg alignment, tibial slope, and preoperative International Cartilage Regeneration & Joint Preservation Society (ICRS) grade. Purpose: To determine (1) the long-term clinical success rate after MAT with bony fixation in a large, single-center cohort of consecutive patients, and (2) if patient-specific and procedural variables influence the clinical, anatomic, and subjective outcomes and risk of failure. Study Design: Case-control study; Level of evidence, 3. Methods: Data on 185 consecutive knees undergoing MAT in a single institution were prospectively collected and screened for inclusion in this study. The minimum follow-up time was 2 years. Radiographic variables (ICRS grade and Kellgren-Lawrence grade) were assessed preoperatively and at follow-up. Subjective patient-reported outcome measures (PROMs) (Lysholm score, Knee injury and Osteoarthritis Outcome Score [KOOS] including subscores, International Knee Documentation Committee [IKDC] score, and visual analog scale [VAS] score) were collected preoperatively and at follow-up. Clinical failure was defined as revision surgery due to graft failure or conversion to total knee arthroplasty. Anatomic failure was considered a tear covering >20% of the allograft, any peripheral tear, and unstable peripheral fixation leading to dislocation of the graft. Subjective failure was defined as Lysholm score ≤65. Preoperative tibial slope and leg alignment were assessed. Survival analyses were performed using the Kaplan-Meier estimate. Univariate and multivariate analyses were performed to determine risk factors for clinical and anatomic failure. Results: A total of 157 knees met inclusion criteria. After a mean follow-up time of 7 ± 3.5 years, 127 (80.9%) knees were free of clinical, anatomic, and subjective failure. Fourteen (8.9%) knees experienced clinical failure, 26 (16.6%) knees were identified as having experienced anatomic failure, and 13 (8.3%) patients experienced subjective failure with a reported Lysholm score of ≤65 at a mean follow-up of 7 years. Concurrent osteochondral allograft transplantation was identified as a predictor of both clinical (hazard ratio [HR], 4.55; 95% CI, 1.46-14.17; P =.009) and anatomic (HR, 3.05; 95% CI, 1.34-6.92; P =.008) failure. Cartilage damage of ICRS grade 3 or 4 of the index compartment conveyed an increased risk for clinical (HR, 3.41; 95% CI, 1.05-11.01; P =.04) and anatomic (HR, 3.04; 95% CI, 1.31-7.11; P =.01) failure. High-grade cartilage damage preoperatively (HR, 10.67; 95% CI, 1.037-109.768; P =.046), patient age >25 years (HR, 5.44; 95% CI, 0.120-246.070; P =.384), and a body mass index >30 (HR, 2.24; 95% CI, 0.748-6.705; P =.149) were associated with subjective failure. PROMs including KOOS and IKDC were significantly improved at final follow-up compared with preoperative scores across all measurements (P <.005). Conclusion: MAT showed good to excellent clinical results at a mean follow-up of 7 years. Low ICRS lesion grade was associated with a higher clinical and anatomic survival rate. Patients with concurrent OCA transplantation are at a higher risk of clinical and anatomic failure, but still report significantly improved PROMs. These results suggest that MAT has a lasting beneficial effect both in isolation and in complex cases with ≥1 concurrent procedures. [ABSTRACT FROM AUTHOR]

Background: Osteochondritis dissecans (OCD) of the knee is a rare but potentially incapacitating disorder in which subchondral bone detaches, leading to an osteochondral fragment that can become unstable and progress into a loose body. The exact cause is unknown, although several biological and mechanical factors have been described. Purpose: To provide insight into epidemiological data of a large cohort of patients affected by OCD of the knee and to identify potential factors contributing to the cause of this disorder. Study Design: Cross-sectional study; Level of evidence, 3. Methods: A total of 236 patients (259 knees) affected by OCD were included in our Knee Registry (2005-2022) and retrospectively analyzed. Patient characteristics were extracted from the medical records. Location and International Cartilage Regeneration & Joint Preservation Society grade (1-4) of OCD were assessed using magnetic resonance imaging. If available, a full-leg standing radiograph was used to assess alignment. Additionally, a statistical scoring system for instability risk was created. Results: A total of 263 OCD lesions were identified in 259 knees, 66.2% on the medial femoral condyle (MFC), 26.6% on the lateral femoral condyle (LFC), 3.8% on the trochlea, 2.7% on the patella, and 0.8% on the lateral tibia plateau. Male patients made up 57.6% of the sample, which had a mean age of 21.8 years. A very high percentage of patients (77.1%; n = 182) practiced sports, of whom 67.6% (n = 123) were engaged in high-impact sports. The location of the OCD lesions and the leg alignment (n = 110) were significantly correlated: MFC lesions were associated with more varus than valgus alignment (47.5% vs 11.3%) and patients with LFC lesions had more valgus than varus alignment (46.7% vs 20.0%; P =.002). Based on age, smoking, sports activity, and preceding trauma, a multivariable scoring system (0-11 points) was created. An increased risk of lesion instability was associated with an increased score: 29.0% at 0 points and 97.0% at 11 points. Conclusion: This study provides detailed epidemiological data for 236 patients affected by OCD of the knee. Older age, smoking, inactivity, and preceding trauma were predictive for instability of OCD lesions. There was an association between OCD of the MFC and varus malalignment and between OCD of the LFC and valgus malalignment. This finding, in combination with the high percentage of patients practicing high-impact sports, suggests an important role for mechanical overload in the pathogenesis of OCD. [ABSTRACT FROM AUTHOR]

Background: There is a significant long-term risk of posttraumatic osteoarthritis (PTOA) after anterior cruciate ligament reconstruction (ACLR). Elucidating the risk factors and successfully identifying at-risk patients is challenging. Purpose/Hypothesis: The purpose of this study was to produce machine learning survival models that can identify (1) patients at risk of symptomatic PTOA and (2) patients who are at risk of undergoing total knee arthroplasty (TKA) after ACLR. It was hypothesized that these models would outperform traditional Kaplan-Meier estimators. Study Design: Case-control study; Level of evidence, 3. Methods: A geographic database was used to identify patients undergoing ACLR between 1990 and 2016 with a minimum 7.5-year follow-up. Models were used to analyze various factors to predict the rate and time to (1) symptomatic osteoarthritis and (2) TKA using random survival forest (RSF) algorithms. Performance was measured using out-of-bag (OOB) c-statistic, calibration, and Brier score. The predictive performances of the RSF models were compared with Kaplan-Meier estimators. Model interpretability was enhanced utilizing global variable importance and partial dependence curves. Results: A total of 974 patients with ACLR and a minimum follow-up of 7.5 years were included; among these, 215 (22.1%) developed symptomatic osteoarthritis, and 25 (2.6%) progressed to TKA. The RSF algorithms achieved acceptable good to excellent predictive performance for symptomatic arthritis (OOB c-statistic, 0.75; Brier score, 0.128) and progression to TKA (OOB c-statistic, 0.89; Brier score, 0.026), respectively. Significant predictors of symptomatic PTOA included increased pain scores, older age, increased body mass index, increased time to ACLR, total number of arthroscopic surgeries before the diagnosis of arthritis, positive pivot-shift test after reconstruction, concomitant chondral injury, secondary meniscal tear, early (<250 days) or delayed (>500 days) return to sports or activity, and use of allograft. Significant predictors for TKA included older age, increased pain scores, total number of arthroscopic surgeries, high-demand activity/occupation, hypermobility, higher body mass index, systemic inflammatory disease, increased time to surgery, early (<250 days) or delayed (>500 days) return to sports or activity, and midsubstance tears. The Brier score over time revealed that RSF models outperformed traditional Kaplan-Meier estimators. Conclusion: Machine learning survival models were used to reliably identify patients at risk of developing symptomatic PTOA, and these models consistently outperformed traditional Kaplan-Meier estimators. Strong predictors for the development of PTOA after ACLR included increased pain scores at injury and postoperative visit, older age at injury, total number of arthroscopic procedures, positive postoperative pivot-shift test, and secondary meniscal tear. [ABSTRACT FROM AUTHOR]

Background: Osteochondritis dissecans (OCD) is a disorder originating in the subchondral bone, leading to focal lesions with risk of fragmentation and secondary damage of the articular cartilage. It remains controversial if surgical treatment of such lesions is equally successful in skeletally immature and mature patients. Purpose: To determine (1) the long-term clinical success rate after internal fixation of unstable OCD in skeletally immature and mature patients based on physeal status, (2) if patient-specific and procedural variables influence the risk of failure, and (3) patient-reported outcome measures over time. Study Design: Cohort study; Level of evidence, 3. Methods: A multicenter retrospective cohort study was conducted investigating skeletally immature and mature patients treated for unstable OCD lesions of the knee between 2000 and 2015. The healing rate was assessed by radiological imaging and clinical follow-up. Failure was defined as any definitive reoperation for the initially treated OCD lesion. Results: A total of 81 patients met inclusion criteria, including 25 skeletally immature patients and 56 patients with closed physes at the time of surgery. After a mean follow-up time of 11.3 ± 4 years, 58 (71.6%) patients had healed lesions, whereas the lesions failed to heal in 23 (28.4%) patients. No significant difference in risk of failure was observed based on physeal maturation status (hazard ratio, 0.78; 95% CI, 0.33-1.84; P =.56). Lateral versus medial condylar lesion location conferred an increased risk of failure (P <.05) for both skeletally immature and mature patients. Multivariate analysis of skeletal maturity status showed that a lateral femoral condylar location was an independent risk factor for failure (hazard ratio, 0.22; 95% CI, 0.1-0.5; P <.05). The mean patient-reported outcome scores (International Knee Documentation Committee [IKDC] score and Knee injury and Osteoarthritis Outcome Score [KOOS]) increased significantly after surgery and remained high at the final follow-up (P <.05). The final scores (mean ± SD) at a mean follow-up of 135.8 months (range, 80-249 months) were IKDC, 86.6 ± 16.7; KOOS Pain, 88.7 ± 18.1; KOOS Symptoms, 89.3 ± 12.6; KOOS Activities of Daily Living, 89.3 ± 21.6; KOOS Sport and Recreation, 79.8 ± 26.3; and KOOS Quality of Life, 76.7 ± 26.3. Conclusion: The long-term results after internal fixation of OCD fragments show high rates of healing and sustainable subjective improvement of knee function and quality of life. A healing rate of 72% was noted at a mean follow-up of 11.3 years. The stage of skeletal maturity had no significant influence on the rate of failure. Lateral femoral condylar lesion location is an independent risk factor for failure in skeletally mature and immature patients. [ABSTRACT FROM AUTHOR]

Background: Patellar instability has the highest incidence in adolescents aged between 14 and 18 years. The unique relationship between the medial patellofemoral ligament (MPFL) and the distal femoral physis in skeletally immature patients warrants precisely positioned MPFL graft insertion. A paucity of data are available evaluating the results of MPFL reconstruction using allograft tendon before skeletal maturity. Purposes: (1) To assess the results of MPFL reconstruction using allograft tendon in skeletally immature patients by analyzing redislocation and reoperation rates, radiological outcomes, and patient-reported outcomes and (2) to determine whether epidemiological, intraoperative, or radiographic factors influence recurrent instability and clinical outcomes. Study Design: Case series; Level of evidence, 4. Methods: Prospectively collected data were retrospectively analyzed for 69 skeletally immature patients who experienced a first-time or recurrent lateral patellar dislocation and were treated with anatomic MPFL reconstruction. Inclusion criteria were MPFL reconstruction using allograft and the availability of preoperative magnetic resonance imaging scans in the presence of open or partially open physes. Patients with <2 years of follow-up and patients with previous surgeries on the same knee were excluded from the study. Preoperative radiographic imaging was reviewed and analyzed. Trochlear dysplasia, tibial tubercle–trochlear groove distance, and patellar height were evaluated. Descriptive data, concomitant injuries, surgical procedure details, complications, and postoperative history were assessed via review of medical records and patient charts. Validated patient-reported and surgeon-measured outcomes were collected pre- and postoperatively, including Kujala score, Lysholm score, and Tegner activity score. Return-to-sports rate was assessed. The influence of epidemiological, intraoperative, and radiographic parameters on the redislocation rates and clinical outcomes was assessed using a multiple linear regression model. Results: A total of 79 physeal-sparing MPFL reconstructions (69 patients) met the inclusion criteria. The mean age of the patient cohort was 14.7 ± 1.8 years (range, 8.5-16.9 years). Within the mean follow-up time of 37.9 ± 12.1 months (range, 24-85 months after surgery, there were 12 patients with clinical failures resulting in reoperation. Eleven patients experienced a redislocation of the patella, and 1 patient sustained a transverse noncontact patellar fracture 6 months after index surgery that required operative fixation. No injuries to the distal femoral physes were clinically observed. At the final follow-up, patients had a mean Lysholm score (1-100) of 96.5 ± 6.7, a mean Kujala score (1-100) of 96.5 ± 7.4, and a mean Tegner Activity Scale score (1-10) of 4.9 ± 1.3. Patellar height and trochlear dysplasia did not influence redislocation or clinical scores. In total, 57 of the 63 patients (90.5%) who were engaged in sports before injury returned to the same or higher level of competition. In a subgroup analysis of patients who underwent isolated MPFL reconstruction (n = 44) without concomitant procedures, 9 patients (20.5%) experienced failure and had a redislocation. A univariate analysis of hazards for failure based on patient-specific variables was carried out. A body mass index ≥30 conveyed a hazard ratio of 2.51 (95% CI, 0.63-10.1; P =.19), and the tibial tubercle-trochlear groove distance by increments of 1 mm was associated with a hazard ratio of 2.02 (95% CI, 0.51-8.11; P =.32). Conclusion: Physeal-sparing anatomic reconstruction of the MPFL using an allograft tendon in skeletally immature patients was a safe and effective treatment for patellar instability, regardless of patellar height and trochlear dysplasia. Failure rates decreased when the MPFL reconstruction was performed concomitantly with a tibial tubercle osteotomy. [ABSTRACT FROM AUTHOR]

Background: Meniscal allograft transplant (MAT) is an important treatment option for young patients with deficient menisci; however, there is a lack of consensus on the optimal method of allograft fixation. Hypothesis: The various methods of MAT fixation have measurable and significant differences in outcomes. Study Design: Meta-analysis; Level of evidence, 4. Methods: A single-arm meta-analysis of studies reporting graft failure, reoperations, and other clinical outcomes after MAT was performed. Studies were stratified by suture-only, bone plug, and bone bridge fixation methods. Proportionate rates of failure and reoperation for each fixation technique were pooled with a mixed-effects model, after which reconstruction of relative risks with confidence intervals was performed using the Katz logarithmic method. Results: A total of 2604 patients underwent MAT. Weighted mean follow-up was 4.3 years (95% CI, 3.2-5.6 years). During this follow-up period, graft failure rates were 6.2% (95% CI, 3.2%-11.6%) for bone plug fixation, 6.9% (95% CI, 4.5%-10.3%) for suture-only fixation, and 9.3% (95% CI, 6.2%-13.9%) for bone bridge fixation. Transplanted menisci secured using bone plugs displayed a lower risk of failure compared with menisci secured via bone bridges (RR = 0.97; 95% CI, 0.94-0.99; P =.02). Risks of failure were not significantly different when comparing suture fixation to bone bridge (RR = 1.02; 95% CI, 0.99-1.06; P =.12) and bone plugs (RR = 0.99; 95% CI, 0.96-1.02; P =.64). Allografts secured using bone plugs were at a lower risk of requiring reoperations compared with those secured using sutures (RR = 0.91; 95% CI, 0.87-0.95; P <.001), whereas allografts secured using bone bridges had a higher risk of reoperation when compared with those secured using either sutures (RR = 1.28; 95% CI, 1.19-1.38; P <.001) or bone plugs (RR = 1.41; 95% CI, 1.32-1.51; P <.001). Improvements in Lysholm and International Knee Documentation Committee scores were comparable among the different groups. Conclusion: This meta-analysis demonstrates that bone plug fixation of transplanted meniscal allografts carries a lower risk of failure than the bone bridge method and has a lower risk of requiring subsequent operations than both suture-only and bone bridge methods of fixation. This suggests that the technique used in the fixation of a transplanted meniscal allograft is an important factor in the clinical outcomes of patients receiving MATs. [ABSTRACT FROM AUTHOR]

Background: Surgical and nonoperative management of anterior cruciate ligament (ACL) injuries seek to mitigate the risk of knee instability and secondary meniscal injury. However, the associated risk and timing of secondary meniscal tears have not been completely elucidated. Purpose: To compare risk and timing of secondary meniscal injury between patients receiving nonoperative management, delayed ACL reconstruction (ACLR), and early ACLR using a machine learning survival analysis. Study Design: Cohort study; Level of evidence, 3. Methods: A geographic database was used to identify and review records of patients with a diagnosis of ACL rupture between 1990 and 2016 with minimum 2-year follow-up. Patients undergoing ACLR were matched 1:1 with nonoperatively treated controls. Rate and time to secondary meniscal tear were compared using random survival forest algorithms; independent models were developed and internally validated for predicting injury-free duration in both cohorts. Performance was measured using out-of-bag c -statistic, calibration, and Brier score. Model interpretability was enhanced using global variable importance and partial dependence curves. Results: The study included 1369 patients who underwent ACLR and 294 patients who had nonoperative treatment. After matching, no significant differences in rates of secondary meniscal tear were found (P =.09); subgroup analysis revealed the shortest periods of meniscal survival in patients undergoing delayed ACLR. The random survival forest algorithm achieved excellent predictive performance for the ACLR cohort, with an out-of-bag c -statistic of 0.80 and a Brier score of 0.11. Significant variables for risk of meniscal tear for the ACLR cohort included time to return to sports or activity ≤350 days, time to surgery ≥50 days, age at injury ≤40 years, and high-impact or rotational landing sports, whereas those in the nonoperative cohort model included time to RTS ≤200 days, visual analog scale pain score >3 at consultation, hypermobility, and noncontact sports. Conclusion: Delayed ACLR demonstrated the greatest long-term risk of meniscal injury compared with nonoperative treatment or early ACLR. Risk factors for decreased meniscal survival after ACLR included increased time to surgery, shorter time to return to sports or activity, older age at injury, and involvement in high-impact or rotational landing sports. Pending careful external validation, these models may be deployed in the clinical space to provide real-time insights and enhance decision making. [ABSTRACT FROM AUTHOR]

Background: Long-term clinical evaluation of patient outcomes can steer treatment choices and further research for cartilage repair. Using mesenchymal stromal cells (MSCs) as signaling cells instead of stem cells is a novel approach in the field. Purpose: To report the 5-year follow-up of safety, clinical efficacy, and durability after treatment of symptomatic cartilage defects in the knee with allogenic MSCs mixed with recycled autologous chondrons in first-in-human study of 1-stage cartilage repair. Study Design: Case series; Level of evidence, 4. Methods: This study is an investigator-driven study aiming at the feasibility and safety of this innovative cartilage repair procedure. Between 2013 and 2014, a total of 35 patients (mean ± SD age, 36 ± 8 years) were treated with a 1-stage cartilage repair procedure called IMPACT (Instant MSC Product Accompanying Autologous Chondron Transplantation) for a symptomatic cartilage defect on the femoral condyle or trochlear groove. Subsequent follow-up after initial publication was performed annually using online patient-reported outcome measures with a mean follow-up of 61 months (range, 56-71 months). Patient-reported outcome measures included the KOOS (Knee injury and Osteoarthritis Outcome Score), visual analog scale for pain, and EuroQol–5 Dimensions. All clinical data and serious adverse events, including additional treatment received after IMPACT, were recorded. A failure of IMPACT was defined as a chondral defect of at least 20% of the index lesion with a need for a reintervention including a surgical procedure or an intra-articular injection. Results: Using allogenic MSCs, no signs of a foreign body response or serious adverse reactions were recorded after 5 years. The majority of patients showed statistically significant and clinically relevant improvement in the KOOS and all its subscales from baseline to 60 months: overall, 57.9 ± 16.3 to 78.9 ± 17.7 (P <.001); Pain, 62.3 ± 18.9 to 79.9 ± 20.0 (P =.03); Function, 61.6 ± 16.5 to 79.4 ± 17.3 (P =.01); Activities of Daily Living, 69.0 ± 19.0 to 89.9 ± 14.9 (P <.001); Sports and Recreation, 32.3 ± 22.6 to 57.5 ± 30.0 (P =.02); and Quality of Life, 25.9 ± 12.9 to 55.8 ± 26.8 (P <.001). The visual analog scale score for pain improved significantly from baseline (45.3 ± 23.6) to 60 months (15.4 ± 13.4) (P <.001). Five cases required reintervention. Conclusion: This is the first study showing the midterm safety and efficacy of the proof of concept that allogenic MSCs augment 1-stage articular cartilage repair. The absence of serious adverse events and the clinical outcome support the longevity of this unique concept. These data support MSC-augmented chondron transplantation (IMPACT) as a safe 1-stage surgical solution that is considerably more cost-effective and a logistically advantageous alternative to conventional 2-stage cell-based therapy for articular chondral defects in the knee. [ABSTRACT FROM AUTHOR]

Background: There are limited data comparing the outcomes of similarly matched patients with a medial meniscus posterior root tear (MMPRT) treated with nonoperative management, partial meniscectomy, or repair. Purpose/Hypothesis: The purpose was to compare treatment failure, clinical outcome scores, and radiographic findings for a matched cohort of patients who underwent either nonoperative management, partial meniscectomy, or transtibial pull-through repair for an MMPRT. We hypothesized that patients who underwent meniscus root repair will have lower rates of progression to arthroplasty than patients who were treated with nonoperative management or partial meniscectomy. Study Design: Cohort study; Level of evidence, 3. Methods: Patients who underwent transtibial medial meniscus posterior horn root repair were matched by meniscal laterality, age, sex, and Kellgren-Lawrence (K-L) grades to patients treated nonoperatively or with a partial meniscectomy. Progression to arthroplasty rates, International Knee Documentation Committee and Tegner scores, and radiographic outcomes were analyzed between groups. Results: Forty-five patients were included in this study (15 nonoperative, 15 partial meniscectomy, 15 root repair). Progression to arthroplasty demonstrated significant differences among treatment groups at a mean of 74 months (nonoperative, 4/15; partial meniscectomy, 9/15; meniscal repair, 0/15; P =.0003). The meniscus root repair group had significantly less arthritic progression, as measured by change in K-L grade from pre- to postoperatively (nonoperative, 1.0; partial meniscectomy, 1.1; meniscal repair, 0.1; P =.001). Conclusion: Meniscus root repair leads to significantly less arthritis progression and subsequent knee arthroplasty compared with nonoperative management and partial meniscectomy in a matched cohort based on patient characteristics. [ABSTRACT FROM AUTHOR]

Background: Anterior cruciate ligament (ACL) injury is one of the most frequent orthopaedic injuries and reasons for time loss in sports and carries significant implications, including posttraumatic osteoarthritis (OA). Instability associated with ACL injury has been linked to the development of secondary meniscal tears (defined as tears that develop after the initial ACL injury). To date, no study has examined secondary meniscal tears after ACL injury and their effect on OA and arthroplasty risk. Purpose: To describe the rates and natural history of secondary meniscal tears after ACL injury and to determine the effect of meniscal tear treatment on the development of OA and conversion to total knee arthroplasty (TKA). Study Design: Cohort study; Level of evidence, 3. Methods: A geographic database of >500,000 patients was reviewed to identify patients with primary ACL injuries between January 1, 1990, and December 31, 2005. Information was collected with regard to ACL injury treatment, rates/characteristics of the secondary meniscal tears, and outcomes, including development of OA and conversion to TKA. Kaplan-Meier and adjusted multivariate survival analyses were performed to test for the effect of meniscal treatment on survivorship free of OA and TKA. Results: Of 1398 primary ACL injuries, the overall rate of secondary meniscal tears was 16%. Significantly lower rates of secondary meniscal tears were noted among patients undergoing acute ACL reconstruction within 6 months (7%) as compared with patients with delayed ACL reconstruction (33%, P <.01) and nonoperative ACL management (19%, P <.01). Of the 235 secondary meniscal tears identified (196 patients), 11.5% underwent repair, 73% partial meniscectomy, and 16% were treated nonoperatively. Tears were most often medial in location (77%) and complex in morphology (56% of medial tears, 54% of lateral tears). At the time of final follow-up, no patient undergoing repair of a secondary meniscal tear (0%) underwent TKA, as opposed to 10.9% undergoing meniscectomy and 6.1% receiving nonoperative treatment (P =.28). Conclusion: Secondary meniscal tears after ACL injury are most common among patients undergoing delayed surgical or nonoperative treatment of their primary ACL injuries. Secondary tears often present as complex tears of the medial meniscus and result in high rates of partial meniscectomy. [ABSTRACT FROM AUTHOR]

Background: Meniscal repair is desirable over resection to prevent postmeniscectomy arthritis, especially among young and active patients. However, long-term data are currently lacking following isolated meniscal repair, particularly in the pediatric population. Purpose/Hypothesis: To report long-term follow-up of isolated meniscal tears treated by meniscal repair in a pediatric and adolescent population and to compare those results with previous midterm follow-up data reported. The authors hypothesized that these patients would have satisfactory function and reoperation rates at long-term follow-up. Study Design: Case series; Level of evidence, 4. Methods: Forty-four patients aged ≤18 years undergoing repair of an isolated meniscal tear (without concomitant anterior cruciate ligament injury) between 1990 and 2005 were included. At the time of final follow-up, recurrent tear, reoperations, and International Knee Documentation Committee (IKDC) and Tegner scores were determined. With logistic regression, the overall failure among tear types was calculated. Wilcoxon rank sum analysis were performed to calculate the differences in clinical outcome for different time points, and Spearman coefficients were calculated for Tegner and IKDC with different variables. Results: At a mean follow-up of 17.6 years (range, 13.1-25.9 years), 32 patients with 33 isolated meniscal repairs (29 male, 3 female) with a mean age of 16.1 years (range, 9.9-18.7 years) at surgery were included in this study. At early follow-up, the overall failure rate was 14 of 33 (42%); complex tears (80%) and bucket-handle tears (47%) had higher overall failure rates when compared with simple tears (18.2%), although only complex tears had a significantly higher failure rate. However, no further failures occurred since midterm follow-up with any tear type. At final follow-up, the mean IKDC score was 92.3, which was significantly increased when compared with preoperative (65.3, P < .0001) and midterm (90.2, P = .01) scores. The mean Tegner score (6.5) was significantly lower than both preoperative (8.3, P < .0001) and midterm (8.4, P < .0001) scores. There was no difference in Tegner or IKDC score for patients with successful versus failed repair. Conclusion: In conclusion, while there was a high early failure rate, this study demonstrated overall good to excellent long-term clinical outcomes after isolated meniscal repair in an adolescent population, even for those requiring reoperation. Early failure and reoperation rates were variable, depending on tear type, with complex multiplanar tears having more failures at short-term follow-up. However, at long-term follow-up, IKDC and Tegner scores were not significantly different for those with complex tears as compared with other tear types. [ABSTRACT FROM AUTHOR]

Background: Responsiveness and the minimal important change (MIC) are important measurement properties to evaluate treatment effects and to interpret clinical trial results. The International Knee Documentation Committee (IKDC) Subjective Knee Form is a reliable and valid instrument for measuring patient-reported knee-specific symptoms, functioning, and sports activities in a population with meniscal tears. However, evidence on responsiveness is of limited methodological quality, and the MIC has not yet been established for patients with symptomatic meniscal tears. Purpose: To evaluate the responsiveness and determine the MIC of the IKDC for patients with meniscal tears. Study Design: Cohort study (design); Level of evidence 2. Methods: This study was part of the ESCAPE trial: a noninferiority multicenter randomized controlled trial comparing arthroscopic partial meniscectomy with physical therapy. Patients aged 45 to 70 years who were treated for a meniscal tear by arthroscopic partial meniscectomy or physical therapy completed the IKDC and 3 other questionnaires (RAND 36-Item Health Survey, EuroQol-5D-5L, and visual analog scales for pain) at baseline and 6-month follow-up. Responsiveness was evaluated by testing predefined hypotheses about the relation of the change in IKDC with regard to the change in the other self-reported outcomes. An external anchor question was used to distinguish patients reporting improvement versus no change in daily functioning. The MIC was determined by the optimal cutoff point in the receiver operating characteristic curve, which quantifies the IKDC score that best discriminated between patients with and without improvement in daily function. Results: Data from all 298 patients who completed baseline and 6-month follow-up questionnaires were analyzed. Responsiveness of the IKDC was confirmed in 7 of 10 predefined hypotheses about the change in IKDC score with regard to other patient-reported outcome measures. One hypothesis differed in the expected direction, while 2 hypotheses failed to meet the expected magnitude by 0.02 and 0.01 points. An MIC of 10.9 points was calculated for the IKDC of middle-aged and older patients with meniscal tears. Conclusion: This study showed that the IKDC is responsive to change among patients aged 45 to 70 years with meniscal tears, with an MIC of 10.9 points. This strengthens the value of the IKDC in quantifying treatment effects in this population. [ABSTRACT FROM AUTHOR]

Background: The anterior cruciate ligament (ACL) has poor regenerative capacity, and an injury leads to loss of function, limiting quality of life and increasing the incidence of osteoarthritis. Surgical interventions can stabilize the joint and improve functional recovery. The delivery of growth factors (GFs) enhances the healing process; however, this is complex in its regulation, is high in costs, has side effects, and can only be accomplished with supraphysiological concentrations and thus is currently not clinically feasible. However, the immobilization of a patient’s endogenous GFs in biomaterials can overcome these problems. Purpose: To develop a method to capture endogenous bone morphogenetic protein–2 (BMP-2) and ultimately show enhanced ACL healing in vivo using this novel methodology. Study Design: Controlled laboratory study. Methods: BMP-2 binding peptides were synthetized, purified, and immobilized on polycaprolactone (PCL) films. The affinity between the peptide and human BMP-2 (hBMP-2) was confirmed with immunofluorescence and enzyme-linked immunosorbent assay. The C2C12 Luc reporter cell line was used to confirm the bioactivity of immobilized BMP-2. For in vivo experiments, the same functionalization technology was applied to the commercially available Polytape, and the functionalized tape was sutured together with the graft used for ACL reconstruction in rats. Each animal underwent reconstruction with either native Polytape (n = 3) or Polytape with BMP-2 binding peptides (n = 3). At 2 and 6 weeks after surgery, the graft was assessed by histology and micro–computed tomography. Results: The covalent immobilization of the peptide in PCL was successful, allowing the peptide to capture hBMP-2, which remained bioactive and led to the osteogenic differentiation of C2C12. In vivo experiments confirmed the potential of the Polytape functionalized with the BMP-2 binding peptide to capture endogenous BMP-2, leading to enhanced bone formation inside the femoral and tibial tunnels and ultimately improving the graft’s quality. Conclusion: The incorporation of BMP-2 binding peptides into materials used for ACL reconstruction can capture endogenous hBMP-2, which enhances the healing process inside the bone tunnels. Clinical Relevance: These results demonstrate the potential of using synthetic peptides to endow biomaterials with novel biological functions, namely to capture and immobilize endogenous GFs. [ABSTRACT FROM AUTHOR]

Background: Osteochondritis dissecans (OCD) is a disorder of unknown origin that can affect knees in skeletally mature and immature patients. Surgical management is an important cornerstone of treatment for unstable OCD lesions. Purpose: To determine the (1) healing rate after internal fixation of unstable OCD between skeletally immature and mature knees, (2) risk factors for failure, and (3) patient-reported outcomes among healed patients. Study Design: Cohort study; Level of evidence, 3. Methods: A multicenter retrospective cohort study was conducted with patients who underwent internal fixation of unstable knee OCD lesions from 2000 to 2015. Skeletal immaturity was defined as open or partially open physes. Healing was assessed through clinical findings and imaging. Definitive reoperation for the same OCD lesion was classified as failure. Results: Among 87 patients included, 66 (76%) had healed lesions at ≥2 years postoperatively, while 21 (24%) failed. Skeletal maturity made no significant difference in failure rate (risk ratio, 0.68; 95% CI, 0.29-1.72; P = .40). For skeletally immature patients, lateral versus medial condylar location conferred an increased hazard of 18.2 (95% CI, 1.76-188.07; P < .01). Multivariate analysis factoring in skeletal maturity showed that lateral condylar location was an independent risk factor for failure (hazard ratio, 4.25; 95% CI, 1.47-19.85; P < .01). Mean patient-reported outcome scores (International Knee Documentation Committee [IKDC] and Knee injury and Osteoarthritis Outcome Score [KOOS]) increased significantly after surgery, except the KOOS symptoms score for the skeletally mature group. Final scores (mean ± SD) were as follows at a mean follow-up of 60 months (range, 24-166): IKDC, 83.5 ± 20.2; KOOS pain, 89.7 ± 14.1; KOOS symptoms, 87.4 ± 18.4; KOOS activities of daily living, 93.9 ± 12.7; KOOS sports, 80.7 ± 25.9; KOOS quality of life, 78.9 ± 23.1. Conclusion: Skeletally immature and mature patients heal at comparable rates after internal fixation of OCD lesions, resulting in functional and subjective improvement. Lateral femoral condylar lesion location is an independent risk factor for failure. [ABSTRACT FROM AUTHOR]

Background: Matrix-based cell therapy improves surgical handling, increases patient comfort, and allows for expanded indications with better reliability within the knee joint. Five-year efficacy and safety of autologous cultured chondrocytes on porcine collagen membrane (MACI) versus microfracture for treating cartilage defects have not yet been reported from any randomized controlled clinical trial. Purpose: To examine the clinical efficacy and safety results at 5 years after treatment with MACI and compare these with the efficacy and safety of microfracture treatment for symptomatic cartilage defects of the knee. Study Design: Randomized controlled trial; Level of evidence, 1. Methods: This article describes the 5-year follow-up of the SUMMIT (Superiority of MACI Implant Versus Microfracture Treatment) clinical trial conducted at 14 study sites in Europe. All 144 patients who participated in SUMMIT were eligible to enroll; analyses of the 5-year data were performed with data from patients who signed informed consent and continued in the Extension study. Results: Of the 144 patients randomized in the SUMMIT trial, 128 signed informed consent and continued observation in the Extension study: 65 MACI (90.3%) and 63 microfracture (87.5%). The improvements in Knee injury and Osteoarthritis Outcome Score (KOOS) Pain and Function domains previously described were maintained over the 5-year follow-up. Five years after treatment, the improvement in MACI over microfracture in the co-primary endpoint of KOOS pain and function was maintained and was clinically and statistically significant (P = .022). Improvements in activities of daily living remained statistically significantly better (P = .007) in MACI patients, with quality of life and other symptoms remaining numerically higher in MACI patients but losing statistical significance relative to the results of the SUMMIT 2-year analysis. Magnetic resonance imaging (MRI) evaluation of structural repair was performed in 120 patients at year 5. As in the 2-year SUMMIT (MACI00206) results, the MRI evaluation showed improvement in defect filling for both treatments; however, no statistically significant differences were noted between treatment groups. Conclusion: Symptomatic cartilage knee defects 3 cm² or larger treated with MACI were clinically and statistically significantly improved at 5 years compared with microfracture treatment. No remarkable adverse events or safety issues were noted in this heterogeneous patient population. [ABSTRACT FROM AUTHOR]

A letter to the editor in response to the article "Characterized Chondrocyte Implantation Results in Better Structural Repair When Treating Symptomatic Cartilage Defects of the Knees in a Randomized Controlled Trial Versus Microfracture," published in the February 2008 issue, along with a response from the author of the same, Daniël B. F. Saris, is presented.