Does high knee flexion cause separation of meniscal repairs?

Area of Science:

• Orthopedic Surgery
• Biomechanics
• Sports Medicine

Background:

• Clinical studies show no outcome difference between restrictive and nonrestrictive protocols post-meniscal repair.
• Surgeons often restrict range of motion due to concerns about stressing the repair.

Purpose of the Study:

• To determine if large acute medial meniscal tears gap during simulated open chain exercises at high flexion angles.
• To assess if a repaired construct using vertical mattress sutures exhibits gapping.

Main Methods:

• Controlled laboratory study using 6 fresh-frozen cadaveric knees.
• Tantalum beads implanted in medial menisci to measure displacement via radiostereometric analysis (RSA).
• Testing performed on intact, torn, and repaired menisci under simulated open chain flexion with quadriceps and hamstring loading.

Main Results:

• Longitudinal tears resulted in meniscal compression, not gapping, during knee flexion.
• After repair with vertical mattress sutures, meniscal displacement approached intact values, except in the mid-posterior region.
• The repaired meniscus showed increased compression in the mid-posterior region compared to the intact state.

Conclusions:

• Acute posteromedial meniscal tears and repairs with vertical mattress sutures compress in the transverse plane at high flexion angles under physiologic loads.
• Repaired meniscal kinematics more closely resemble intact than torn states, particularly near the MCL and root.
• Nonrestrictive, unresisted open kinetic chain range of motion protocols are unlikely to overstress meniscal repairs.