Howard R. Galloway

Association between abnormal kinematics and degenerative change in knees of people with chronic anterior cruciate ligament deficiency: A magnetic resonance imaging study

Progressive degeneration of the anterior cruciate ligament (ACL) deficient knee may be partly due to chondral trauma at the time of ACL rupture and repeat episodes of subluxation, but also due to aberrant kinematics altering the wear pattern at the tibiofemoral interface. The hypothesis that altered kinematics, represented by the tibiofemoral contact pattern, would be associated with articular cartilage degeneration in ACL-deficient knees was tested in a cross-sectional study of 23 subjects with a history of > 10 years ACL deficiency without knee reconstruction. Subjects were aged 31 to 67 years. Eleven were male, 12 were female. Sagittal magnetic resonance imaging (MRI) scans enabled tibiofemoral contact mapping as subjects performed a closed-chain leg-press. Images were acquired at 15 degree intervals from 0 degrees to 90 degrees knee flexion. Articular cartilage degeneration was assessed by diagnostic MRI and where possible, arthroscopy. The ACL-deficient knees had a posterior tibiofemoral contact pattern on the tibial plateau compared to the healthy knees (F((1,171)) = 9.2, p = 0.003). The difference appeared to be seen in the medial compartment (F((1,171)) = 3.2, p = 0.07), though this failed to reach significance. Articular cartilage degeneration in the medial compartment was related to the variation of the tibiofemoral contact pattern (r = -0.53, p = 0.01). Articular cartilage degeneration was not related to time since injury (r = -0.16, p = 0.65). The association between aberrant kinematics and degenerative change may stimulate thinking on the role of dynamic stability and neuromuscular co-ordination in joint protection.

Does anterior cruciate ligament reconstruction restore normal knee kinematics? A PROSPECTIVE MRI ANALYSIS OVER TWO YEARS

This prospective study used magnetic resonance imaging to record sagittal plane tibiofemoral kinematics before and after anterior cruciate ligament reconstruction using autologous hamstring graft. Twenty patients with anterior cruciate ligament injuries, performed a closed-chain leg-press while relaxed and against a 150 N load. The tibiofemoral contact patterns between 0 degrees to 90 degrees of knee flexion were recorded by magnetic resonance scans. All measurements were performed pre-operatively and repeated at 12 weeks and two years. Following reconstruction there was a mean passive anterior laxity of 2.1 mm (sd 2.3), as measured using a KT 1000 arthrometer, and the mean Cincinnati score was 90 (sd 11) of 100. Pre-operatively, the medial and lateral contact patterns of the injured knees were located posteriorly on the tibial plateau compared with the healthy contralateral knees (p=0.014), but were no longer different at 12 weeks (p=0.117) or two years postoperatively (p=0.909). However, both reconstructed and healthy contralateral knees showed altered kinematics over time. At two years, the contact pattern showed less posterior translation of the lateral femoral condyle during flexion (p<0.01).