Tibiofemoral Load Sharing and Lateral Meniscal Function Are Restored in Tibia- and Capsular-Based Repair of Type 3 Lateral Meniscal Oblique Radial Tears.

BACKGROUND

There is a paucity of literature evaluating (1) changes in lateral compartment tibiofemoral contact mechanics and lateral meniscal function and (2) the effect of varying repair constructs in treating partial-thickness (type 3) lateral meniscal oblique radial tears (LMORTs).

HYPOTHESIS: (1) Type 3 LMORTs would significantly alter lateral compartment contact mechanics and meniscal function when compared with the intact state, and (2) tibia-based suture anchor repair would more effectively restore these metrics to native levels when compared with capsular-based side-to-side repair or debridement.

STUDY

DESIGN

Controlled laboratory study.

METHODS

Eight nonpaired fresh-frozen human cadaveric knees were utilized for this study. Each specimen was tested across 5 states in the following order: intact lateral meniscus, LMORT type 3 (partial thickness) tear created 12 mm lateral to the root attachment, tibia-based suture anchor fixation, capsular-based side-to-side repair, and debridement. For each state, 4 knee flexion angles were tested in random order: 0°, 30°, 60°, and 90° with 500 N of axial load. The following were recorded for each state: contact area, mean contact pressure, peak contact pressure of the lateral compartment, lateral meniscal extrusion, and 3-dimensional lateral meniscal anterior root forces (via use of a novel 3-axis sensor). Differences in means of outcomes were compared by 2-way repeated measures analysis of variance.

RESULTS

Type 3 LMORTs were associated with significantly increased contact pressures and extrusion at all flexion angles and decreased contact area at high knee flexion angles as compared with the intact state. The tear state was also associated with significantly decreased forces experienced at the lateral meniscal anterior root attachment versus the intact state. Tibia-based suture anchor and capsular-based side-to-side repair restored contact mechanics, extrusion, and anterior root forces to the intact state, with no significant difference between the repair conditions. Debridement was associated with worse or no better outcomes than tear state alone.

CONCLUSION

In a cadaveric model, type 3 LMORTs significantly alter tibiofemoral joint mechanics and lateral meniscal force transmission, and repair of these tears restores the native state, regardless of repair construct. Clinically, this study provides biomechanical support for the repair of type 3 LMORTs at the time of anterior cruciate ligament reconstruction.

CLINICAL RELEVANCE: This study provides data regarding the effects of type 3 LMORTs and LMORT repair on tibiofemoral contact mechanics and meniscal function. The results of our study provide additional biomechanical justification for LMORT repair at the time of anterior cruciate ligament reconstruction.