Knees of patients with chronic anterior cruciate ligament instability and who were awaiting surgery were examined with respect to increasing co-morbidity following diagnosis and subsequently during surgical reconstruction.

141 patients were included in this study. All had undergone initial arthroscopic evaluation of their unstable knees following diagnosis and subsequently a further arthroscopy was performed at a later stage during hamstring anterior cruciate ligament reconstruction. All injuries to the menisci and articular cartilage were recorded using a standardised evaluation form. The Lysholm and Tegner scores were obtained as well as knee stability using the KT-2000 arthrometer.

Successive deterioration in the Lysholm and Tegner scores and the arthrometric side to side difference was noted with time since injury. Initial arthroscopic examination of the knee revealed that 66 patients (46%) had at least one meniscal injury necessitating treatment whilst 67 (47.5%) had at least one chondral lesion on the femoral condyles. 22 patients (15.6%) presented with chondral lesions of the articular surface of the patella. During definitive ACL reconstruction when a second arthroscopy was performed, it was noted that 111 patients (78.7%) had meniscal pathology, 102 patients (72.34%) had intraarticular chondral lesions and the patella was affected in 41 cases (29%).

The delay between initial arthroscopy and stabilization was 16 +/− 5.2 months (range 7–19 months). The difference in the arthroscopic findings between the first and second arthroscopic inspections in terms of meniscal and chondral lesions was statistically significant.

Knee instability due to chronic ACL deficiency poses a serious threat to the menisci and the articular cartilage of the affected knee. The severity of these lesions increases with time since injury. ACL reconstruction should be undertaken as soon as possible in those individuals with uncompensated anterior cruciate ligament instability.