Quadriceps muscle strength at 2 years following anterior cruciate ligament reconstruction is associated with tibiofemoral joint cartilage volume

Purpose Quadriceps strength deficits following anterior cruciate ligament reconstruction (ACLR) are linked to altered lower extremity biomechanics, tibiofemoral joint (TFJ) space narrowing and cartilage composition changes. It is unknown, however, if quadriceps strength is associated with cartilage volume in the early years following ACLR prior to the onset of posttraumatic osteoarthritis (OA) development. The purpose of this cross-sectional study was to examine the relationship between quadriceps muscle strength (peak and across the functional range of knee flexion) and cartilage volume at similar to 2 years following ACLR and determine the influence of concomitant meniscal pathology. Methods The involved limb of 51 ACLR participants (31 isolated ACLR; 20 combined meniscal pathology) aged 18-40 years were tested at 2.4 +/- 0.4 years post-surgery. Isokinetic knee extension torque generated in 10 degrees intervals between 60 degrees and 10 degrees knee flexion (i.e. 60 degrees-50 degrees, 50 degrees-40 degrees, 40 degrees-30 degrees, 30 degrees-20 degrees, 20 degrees-10 degrees) together with peak extension torque were measured. Tibial and patellar cartilage volumes were measured using magnetic resonance imaging (MRI). The relationships between peak and angle-specific knee extension torque and MRI-derived cartilage volumes were evaluated using multiple linear regression. Results In ACLR participants with and without meniscal pathology, higher knee extension torques at 60 degrees-50 degrees and 50 degrees-40 degrees knee flexion were negatively associated with medial tibial cartilage volume (p < 0.05). No significant associations were identified between peak concentric or angle-specific knee extension torques and patellar cartilage volume. Conclusion Higher quadriceps strength at knee flexion angles of 60 degrees-40 degrees was associated with lower cartilage volume on the medial tibia similar to 2 years following ACLR with and without concomitant meniscal injury. Regaining quadriceps strength across important functional ranges of knee flexion after ACLR may reduce the likelihood of developing early TFJ cartilage degenerative changes.