Effect of quadriceps strength on the patellofemoral joint cartilage lesions after anterior cruciate ligament reconstruction

Abstract

Objective To evaluate the effect of quadriceps strength on the patellofemoral joint cartilage status after anterior cruciate ligament (ACL) reconstruction. Methods Seventy-six patients undergoing ACL reconstruction in our institute received second-look arthroscopy for the metal staple removal at least one year postoperatively from December 2009 to August 2013. The patients consisted of 51 males and 25 females with an average age of 27.6 years (range: 16 to 44) at the time of ACL recon-struction. Patients underwent standardized isokinetic testing for both quadriceps and hamstrings before second-look arthroscopy. Arthroscopic evaluation of patella and trochlea cartilage status for all patients was performed at the index ACL reconstruction and the second-look arthroscopy. The effect of quadriceps and hamstrings strength on patellofemoral joint cartilage status was investi-gated. Results The average follow-up time from ACL reconstruction to second-look arthroscopy was 25.3 months (range: 12 to 51). After ACL reconstruction, 45% of patients had a 20% or greater quadriceps deficit and 22% had hamstring weakness of 20% or more. Patients were divided into 2 groups: less than 20% quadriceps deficit group with 42 patients and 20% or greater deficit group with 34 patients. For patella cartilage, chondral worsening was found in 9 patients (21%) and 16 patients (47%) in two groups respectively, with a statistically significant difference in favor of the former group. The mean worsening grades of patella cartilage were 0.10 and 0.68 respectively, whereby the former group was significantly less than that in the latter group. For trochlea cartilage, chondral worsening was detected in 11 patients (26%) and 11 patients (32%) in these two groups respectively, with no significant difference. The mean worsening grades of trochlea cartilage were 0.55 and 0.71 in the two groups respectively, with no significant difference. Conclusion A recovery of>80% in quadriceps strength after ACL reconstruction could lead to less severe cartilage damage at the patella. Key words: Anterior cruciate ligament; Muscle strength; Cartilage; Wounds and injuries