Early osteoarthritis after untreated anterior meniscal root tears: An in vivo animal study

Background: Meniscal root tears cause menisci and their insertions to inadequately distribute loads and potentially leave underlying articular cartilage unprotected. Untreated meniscal root tears are becoming increasingly recognized to induce joint degradation; however, little information is known about anterior meniscal root tears and how they affect joint tissue. Purpose: To observe the early degenerative changes within the synovial fluid, menisci, tibial articular cartilage, and subchondral bone after arthroscopic creation of untreated anterior meniscal root tears. Study Design: Controlled laboratory study. Methods: Anterolateral meniscal root tears were created in 1 knee joint of 5 adult Flemish Giant rabbits, and anteromedial meniscal root tears were created in 4 additional rabbits. The contralateral limbs were used as nonoperated controls. The animals were euthanized at 8 weeks postoperatively; synovial fluid was aspirated, and tissue samples of menisci and tibial articular cartilage were collected and processed for multiple analyses to detect signs of early degeneration. Results: Significant changes were found within the synovial fluid, meniscal tissue, and tibial subchondral bone of the knees with anterior meniscal root tears when compared with controls. There were no significant changes identified in the tibial articular cartilage when comparing the tear groups with controls. Conclusion: This study demonstrated early degenerative changes within the synovial fluid, menisci, and tibial subchondral bone when leaving anterior meniscal root tears untreated for 8 weeks. The results suggest that meniscal tissue presents measurable, degenerative changes prior to changes within the articular cartilage after anterior meniscal root tears. Anterior destabilization of the meniscus arthroscopically may lead to measurable degenerative changes and be useful for future in vivo natural history and animal repair studies. Clinical Relevance: The present study is the first to investigate various tissue changes after anterior meniscal root tears of both the medial and lateral menisci. The results from this study suggest that degenerative changes occur within the synovial fluid, meniscus, and tibial subchondral bone prior to any measurable changes to the tibial articular cartilage. Further studies should expand on this study to evaluate how these components continue to progress when left untreated for long periods

Peroneus Brevis to Longus Tendon Transfer in the Treatment of the Flexible Progressive Collapsing Foot Deformity: A Cadaveric Study

Category: Midfoot/Forefoot; Hindfoot Introduction/Purpose: Although operative treatment of the flexible progressive collapsing foot deformity (PCFD) remains controversial, correction of residual forefoot varus and stabilization of the medial column are important components of reconstruction. An opening wedge medial cuneiform osteotomy or first tarsometatarsal fusion is traditionally performed to plantarflex the first metatarsal. More recently, tendon transfers such as a peroneus brevis (PB) to peroneus longus (PL) have been proposed. However, there is little data to support their use. The aim of our study was to determine the effect of an isolated PB- to-PL transfer (PBT) on medial column and hindfoot joint kinematics in a simulated PCFD (sPCFD) cadaveric model using a robotic gait simulator. We hypothesized that a PBT in a sPCFD model would partially restore kinematics to the intact state. Methods: A validated six-degree of freedom robot (Baxter et al., 2016) was used to simulate the stance phase of level walking for 6 mid-tibia cadaveric specimens (3 male; age: 72 ± 8 years). An eight-camera motion capture system was used to track reflective markers fixed to bones of the foot and ankle. Three conditions were tested for each specimen: intact, sPCFD (Henry et al., 2022), and after PBT. The PBT was performed by transecting the PB and advancing the proximal stump 1 cm into the PL (Sanhudo, 2019). Outcome measures included kinematics of the talonavicular, subtalar, and first tarsometatarsal joints. Maximum differences between the PBT and sPCFD conditions and 95% confidence intervals (95%CIs) were calculated. The percent deformity correction was determined by dividing the difference between the PB and sPCFD states by the difference between the intact and sPCFD states at the site of maximum deformity correction. Results: Relative to the sPCFD condition, the PBT resulted in a maximum increase in talonavicular plantarflexion of 1.8° (95%CI 0.9°-2.7°) with 159% correction during midstance, decrease in talonavicular abduction of 1.5° (95%CI 0.3°-2.8°) with 65% correction during midstance, and decrease in talonavicular eversion of 2.4° (95%CI 1.2°-3.8°) with 90% correction during mid-to- late stance. All deformities had consistent correction at the talonavicular joint during stance (Figure 1). Additionally, the PBT resulted in a maximum increase in subtalar plantarflexion by 0.8° (95%CI 0.3°-1.8°) with 155% correction in early stance, decrease in subtalar abduction by 0.8° (95%CI 0.5°-1.2°) with 191% correction during early stance, and decrease in subtalar eversion by 1.5° (95%CI 0.5°-2.2°) with 178% correction during mid-stance. There was no effect on first tarsometatarsal joint kinematics. Conclusion: A PB-to-PL transfer in a sPCFD model resulted in the correction of multiple deformities including increased plantarflexion and decreased abduction at the talonavicular joint compared to the sPCFD without the transfer, most notably during PB activation in stance. The PBT also decreased eversion at the talonavicular and subtalar joints. Our results suggest that the addition of a PBT as part of the surgical management of the flexible PCFD contributes to correction of the residual forefoot varus, midfoot abduction, and hindfoot valgus deformities by plantarflexing through the medial column and removing a deforming force on the foot by the PB

Overlap between Anterior Cruciate Ligament and Anterolateral Meniscal Root Insertions

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

Does anatomic single-bundle ACL reconstruction using hamstring autograft produce anterolateral meniscal root tearing?

BACKGROUND: To determine if tibial tunnel reaming during anatomic single-bundle anterior cruciate ligament (ACL) reconstruction using hamstring autograft can result in anterolateral meniscal root injury, as diagnosed by magnetic resonance imaging (MRI). METHODS: A case series of 104 primary anatomic single-bundle ACL reconstructions using hamstring autograft was retrospectively reviewed. Pre- and post-operative (>1 year) MRIs were radiologically evaluated for each patient, with a lateral meniscus extrusion > 3 mm at the level of the medial collateral ligament midportion on a coronal MRI, to establish anterolateral meniscal root injury. RESULTS: No patients presented radiological findings of anterolateral meniscal root injury in this case series. CONCLUSIONS: Examining a single-bundle ACL reconstruction technique using hamstring autograft that considered tibial tunnel positioning in the center of the tibial footprint, this case series found no evidence of anterolateral meniscal root injury in patient MRIs, even more than 1-year post-operation