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Background: Injuries to the fibular collateral ligament (FCL) seldom occur in isolation and may present with a concomitant injury to the biceps femoris tendon and anterior cruciate ligament (ACL). Injuries to structures of the posterolateral corner (PLC) lead to varus and rotational instability of the knee, subjecting the cruciate ligaments to increased forces that may result in graft failure. Therefore, reconstruction of these structures should be performed concurrently with the ACL. Indications: Grade III FCL injuries heal poorly without operative treatment and often result in residual varus instability of the knee that increases medial knee compartment forces, and forces on both the native ACL and the graft status post ACL reconstruction. Therefore, preservation of biomechanical stability and long-term health of the knee are reliant on addressing injuries to the PLC surgically. Technique Description: A key concept of this surgical technique is a meticulous peroneal nerve neurolysis in the setting of altered biceps femoris anatomy, and the proper order of the surgical steps for tunnel creation, graft passage, and fixation and suture anchor insertion to achieve optimal patient outcomes. The described technique involves a lateral surgical approach, peroneal neurolysis, and preparation of fibular and femoral FCL tunnels, followed by a Bone-patellar tendon-bone graft (BTB) graft harvest. Attention is then turned to intra-articular work including the diagnostic arthroscopy, femoral and tibial tunnel preparation, passage of the ACL graft, and fixation of the grafts in femoral tunnels. Last, fixation is achieved in the following order: FCL graft on fibula, ACL graft on tibia, and biceps femoris tendon to fibular head. Results: Compared with the preoperative state, Moulton et al reported significant improvements in the average Lysholm and Western Ontario scores at 2.7 years postoperatively following anatomic FCL reconstrution. Furthermore, Thompson et al reported on primary suture anchor repair of distal biceps femoris in 22 elite athletes and reported that all patients had returned to their preinjury level of sporting activity at 2-year follow-up. Discussion: Anatomic reconstructions of the FCL and ACL, such as the one described in our technique, effectively restore near native knee biomechanics and offer superior clinical outcomes compared with nonanatomic-based FCL reconstructions. Patient Consent Disclosure Statement: The author(s) attests that consent has been obtained from any patient(s) appearing in this publication. If the individual may be identifiable, the author(s) has included a statement of release or other written form of approval from the patient(s) with this submission for publication.

Background: Anterior cruciate ligament (ACL) reconstructions in skeletally immature patients have an increased risk of graft failure and a decreased rate of successful return to sports. Anterior cruciate ligament reconstructions (ACLRs) combined with lateral extra-articular tenodesis (LET) procedures are reported to limit anterolateral rotary instability of the knee, decreasing tension on the ACL graft. However, the open physes found in pediatric patients present unique challenges for ACLR. This video demonstrates a technique to avoid the femoral physis and necessary precautions for performing an ACLR with LET in a skeletally immature patient. Indications: The indications for combined ACLR and LET, as opposed to ACLR alone, mainly center on the risk factors for graft failure. These include the following: posterior tibial slope >12°, revision ACLR, high-grade pivot shift on physical examination, meniscal deficiency, generalized ligamentous hyperlaxity, and—especially pertinent to this procedure—skeletally immature patients. Technique Description: Standard plain radiographs and long-leg alignment films, along with a magnetic resonance imaging (MRI) study, are necessary to assess for malalignment, bone age, and concomitant meniscal and chondral pathology. This technique describes the senior author’s preferred technique for pediatric ACLR with LET. The senior author’s preferred order of operations includes performing the autologous hamstring graft harvest and LET before performing the diagnostic arthroscopy. This is followed by the intra-articular work including the ACLR. It is also the senior author’s preference to perform physeal-sparing femoral tunnels, using fluoroscopy for tunnel placement. Results: Getgood et al reported that an ACLR with an LET in young patients with a high risk of graft failure had a significant reduction in graft rupture compared to an ACLR alone. Furthermore, Noyes et al reported a significantly lower rate of graft failure and a higher rate of return to sports in those who received LET in addition to ACLR compared with those who received ACLR alone. Discussion: An ACLR combined with an LET has been reported to reduce graft failure rates and improve clinical outcomes in high-risk patients. An ACLR with LET may also be considered in skeletally immature patients with appropriate indications and extra precautions to avoid growth arrest or deformity. Patient Consent Disclosure Statement: The author(s) attests that consent has been obtained from any patient(s) appearing in this publication. If the individual may be identifiable, the author(s) has included a statement of release or other written form of approval from the patient(s) with this submission for publication.

Background: Valgus malalignment leads to excessive loading of the lateral compartment and has been associated with lateral compartment meniscal injuries and early-onset knee osteoarthritis. Distal femoral osteotomy (DFO) is a treatment option that allows correction of the mechanical access to offload the lateral compartment. Lateral opening-wedge distal femoral osteotomy and medial meniscal root repairs are both aimed to address the pathologic biomechanics of the tibiofemoral joint and when successful can delay or even prevent progression to end-stage osteoarthritic changes in the lateral and medial compartment, respectively. Indications: Distal femoral osteotomy is indicated for patients with normal metabolic bone health and valgus malalignment who may present with concurrent lateral meniscal injury, symptomatic lateral compartment arthritis, or a chronic medial collateral ligament tear/laxity. Technique Description: Long-leg alignment radiographs and preoperative magnetic resonance images are required to evaluate the degree of mechanical access deviation and to evaluate for soft tissue injury, as there is often concomitant lateral meniscal or cartilage pathology present. This technique demonstrates the optimal order of surgical steps for DFO with a concurrent medial meniscal root repair. The senior author’s preferred order is to first perform the open lateral approach and expose the lateral cortex for the placement of plate prior to arthroscopic work and excess fluid extravasation. Intra-articular work is then performed with a diagnostic arthroscopy followed by medial meniscal root repair. Finally, the osteotomy and subsequent internal fixation are performed. Results: The literature on opening-wedge DFO outcomes is heterogeneous, with variable rates of successful outcomes and complications. Saithna et al reported that International Knee Documentation Committee and the pain subdomain of Knee injury and Osteoarthritis Outcome Scores significantly improved postoperatively following lateral opening-wedge DFOs in patients with lateral compartment osteoarthritis. The 10-year success rate of varus-producing DFO has been reported to be 64% to 85%. Discussion: We describe a technique for correction of a valgus deformity with opening-wedge DFO and concurrent meniscal root repair. This surgical technique effectively restores the native femoral and tibial axis with appropriate load distribution and also concurrently restores the appropriate function of the medial meniscus which allows axial force dispersion via hoop stresses for the medial compartment. Patient Consent Disclosure Statement: The author(s) attests that consent has been obtained from any patient(s) appearing in this publication. If the individual may be identifiable, the author(s) has included a statement of release or other written form of approval from the patient(s) with this submission for publication.

Growing evidence has revealed the pivotal role of inflammatory biomarkers in the pathogenesis of osteoarthritis. There is significant interest in the prognostic value of select biomarkers, given the potential for early identification and treatment of patients at risk of osteoarthritis prior to the development of irreversible clinical disease. Clinical trials of novel therapeutics that disrupt the inflammatory pathways of osteoarthritis are also ongoing. The purpose of this review is to summarize the current literature on key biomarkers within the context of osteoarthritis pathogenesis, clinical symptom development, and treatment capabilities. Multiple recent studies have established biomarkers that signal the existence of osteoarthritis pathology and the development of clinical symptomology. However, prior to implementation in clinical practice, additional research is required to precisely define the prognostic value for numerous biomarkers and standardize their measurement. Biomarker-driven investigations represent a promising avenue for the early diagnosis and treatment of osteoarthritis.

The posterior cruciate ligament (PCL) is the primary stabilizer to posterior tibial translation of the knee. PCL injuries classically occur as the result of a posteriorly directed force against the anterior part of the tibia. They frequently occur as multiligament injuries or with concomitant cartilage or meniscal injuries. The posterior drawer test is highly sensitive and specific for PCL injuries. Posterior stress radiography is critical for objective assessment of posterior tibial translation and grading of PCL injuries. Grade I and II injuries may be treated nonoperatively, but in general isolated grade III injuries and multiligament injuries require surgical intervention due to the inevitable development of osteoarthritis. Anatomical and biomechanical studies have led to the development of an anatomic double-bundle reconstruction, which has been reported in clinical outcome studies to result in better functional and objective outcomes than single-bundle reconstructions. This article focuses on the clinically and surgically relevant anatomy and biomechanics of the PCL, diagnosis and treatment of PCL injuries, and a description of the anatomic double-bundle PCL reconstruction technique.

A foundational knowledge of the anatomy and biomechanics of meniscal root tears is warranted for proper repair of meniscal root tears and for preventing some of their commonly described iatrogenic causes. Meniscal root tears are defined as either a radial tear occurring within one cm of the root attachment site of the meniscus or a complete bony or soft tissue avulsion of the root attachment altogether. Meniscal root tears disrupt the protective biomechanical function of the native meniscus. Biomechanical analyses of the current techniques for meniscal root repair highlight the importance of restoring menisci to their correct anatomic orientation, thereby restoring their biomechanical function. A comprehensive understanding of the clinical and radiographic presentations of these injuries is critical to preventing their underdiagnosis. The poor long-term outcomes associated with conservative treatment measures, namely, ipsilateral compartment osteoarthritis, warrants the surgical repair of meniscal root tears whenever possible. While excellent patient-reported outcomes exist for the various surgical repair techniques, adherence to stringent post-operative rehabilitation protocols is critical for patients to avoid damaging the integrity of a repaired root. This review will focus on current concepts pertaining to the anatomy, biomechanics, diagnosis, treatment, and postoperative rehabilitation for meniscal root tears.

Rodent open field behavior is highly organized and occurs spontaneously in novel environments. This organization is disrupted in mice with vestibular pathology, suggesting vestibular signals provide important contributions to this behavior. A caveat to this interpretation is that previous studies have investigated open field behavior in adult mice with congenital vestibular dysfunction, and the observed deficits may have resulted from developmental changes instead of the lack of vestibular signals. To determine which aspects of open field behavior depend specifically on vestibular signals, mouse movement organization was examined under dark and light conditions at two time points, 1 and 2 months, after bilateral chemical labyrinthectomy. Our results show that acquired vestibular damage selectively disrupted the organization of open field behavior. Access to visual environmental cues attenuated, but did not eliminate, these significant group differences. Improvement in movement organization from the first to the second testing session was limited to progression path circuity. These observations provide evidence for the role of the vestibular system in maintaining spatial orientation and establishes a foundation to investigate neuroplasticity in brain systems that process self-movement information.

Arm and hand use by the mouse have been studied in a variety of tasks in order to understand the structure of skilled movements and motor learning, the anatomy and function of neural pathways, and to develop animal models of neurological conditions. The present study describes string-pulling by the mouse, a behavior in which a mouse uses hand-over-hand movements to pull down a string that hangs from the top of a test cage. Mice both spontaneously string-pull and also string-pull to obtain cashew nuts tied to the end of the string as food reward. To string-pull, mice sat upright and tracked the string with their nose and then made hand-over-hand movements to reel in the string. A string-pull movement consists of four arm movements (Advance to make purchase, Pull, Push to draw the string down and Lift to return the hand for the next Advance) and four hand movements (Collect to aim the hand, Overgrasp to position the hand, and Grasp to make purchase, and Release). The kinematic profiles of the string-pull movement are distinctive with each hand making similar movements at a rate of 4 cycles per second and with the Lift and Advance movements occurring at a higher speed than Pull and Push movements. The results are discussed in relation to the antecedent repertoire of mouse behavior that lends itself to string-pulling, with respect to the utility of using string-pulling to investigate motor systems and adapting string-pulling to model neurological conditions in mice.