Description
Objectives:
The meniscus, a C-shaped cartilaginous structure within the knee joint, plays a pivotal role in maintaining joint function and stability. Its multifaceted functions include load transmission, shock absorption, joint lubrication, anteroposterior joint stability, and proprioception. In response to meniscal injuries, particularly horizontal cleavage tears (HCT), which account for about 32% of meniscal tears, traditional treatment has often involved partial meniscectomy and transplantation. This approach has been favored for its perceived benefits, enabling swift recovery and the resumption of sports activities. However, the long-term consequences of partial meniscectomy, tied to biomechanical disruptions caused by essential meniscal tissue loss, further complicate matters. Meniscal transplant presents the potential for restoring critical meniscal functions while minimizing the adverse outcomes linked to partial meniscectomy, such as an increased risk of arthritis. Our research aims to comprehensively investigate the biomechanical implications of meniscal transplant compared to partial meniscectomy, as well as intact menisci and those affected by HCT. We assessed contact areas and pressures within the knee joint using a human model to shed light on how these surgical interventions affect joint mechanics.
Methods:
The study involved 7 fresh-frozen human cadaveric knees, from which muscular structures and extensor mechanisms were removed while keeping ligaments intact. To access the tibiofemoral joint, a femoral condyle osteotomy was performed. Pressure-mapping sensors (Tekscan) were placed through a sub-meniscal arthrotomy. Each knee underwent testing at full extension under four conditions (Fig 1): i) intact medial meniscus, ii) 2cm posteromedial horizontal cleavage tear of medial meniscus, iii) partial meniscectomy, and iv) partial medial meniscus transplantation using an allograft tailored to fit the prepared defect. Using a uniaxial load frame (MTS 30/G machine) (Fig 2), tibiofemoral contact pressure and contact area were measured in the medial and lateral compartments at 800 N of axial load, with triplicate measurements for each condition.
Results: The experimental results showed distinctive contact pressure patterns (Fig 3). The intact meniscus displayed a medial peak contact pressure of 2.45±0.41 MPa, while the partial tear showed 2.45±0.52 MPa, meniscectomy exhibited 2.74±0.54 MPa, and transplant demonstrated 2.54±0.15 MPa. On the lateral side, the intact meniscus registered a contact pressure of 2.73±0.16 MPa, the partial tear revealed a higher pressure of 2.61±0.27 MPa, with meniscectomy yielding 2.83±0.31 MPa, and transplant showing 2.61±0.25 MPa. Notably, statistical analysis revealed no significant differences between each group in terms of medial and lateral contact pressures (p < 0.05). However, there was an 11.42% increase in pressure observed between the intact and meniscectomy groups, while there was a 3.67% decrease, indicating a reduction in contact pressure by up to 7.2% compared to the meniscectomy group. The study also focused on contact areas, revealing medial compartment values of 477.93 mm², 383.29 mm², and 394.08 mm² for partial tear, partial meniscectomy, and partial meniscus transplant conditions, respectively. Statistically significant differences emerged between tear and meniscectomy (p = 0.005) and tear and transplant conditions (p = 0.008), but not between meniscectomy and transplant (p = 0.582).
Conclusions: The findings hold important clinical implications. Partial meniscal transplantation showed comparable contact areas to partial meniscectomy in full extension. Notably, across all knees and axial loads, partial transplantation outperformed meniscectomy by restoring and increasing contact area. This supports the idea that partial transplantation could be a non-inferior alternative for repairing horizontal cleavage tears. However, it's important to acknowledge that contact pressure for the partial tear has some limitations, as horizontal cleavage tears are inherently more sensitive and prone to flapping against shear forces rather than compression, which may affect the accuracy of our pressure measurements. These results underscore the potential of partial meniscal transplantation as a viable treatment option, though further enhancements to surgical procedures, graft shaping, and suturing techniques could impact its outcomes due to the technique's novelty. Continued refinements in this operative approach may offer improved effectiveness in addressing meniscal tears and enhancing patient outcomes.
