Early anterior cruciate ligament reconstruction does not affect 5 year change in knee cartilage thickness: secondary analysis of a randomized clinical trial.

OBJECTIVE: To compare 5-year change in femorotibial cartilage thickness in 121 young, active adults with an acute anterior cruciate ligament (ACL) tear randomized to a strategy of structured rehabilitation plus early ACL reconstruction (ACLR) or structured rehabilitation plus optional delayed ACLR. DESIGN: 62 patients were randomized to early ACLR, 59 to optional delayed ACLR. Magnetic resonance imaging (MRI) was acquired within 4 weeks of injury, at two- and 5-years follow-up. Main outcome was 5-year change in overall femorotibial cartilage thickness. Secondary outcomes included the location-independent cartilage ChangeScore, summarizing thinning and thickening in 16 femorotibial subregions. An exploratory as-treated comparison was performed additionally. RESULTS: Baseline and at least one follow-up MRI were available for 117 patients. Over 5 years, a comparable increase in overall femorotibial cartilage thickness was observed for patients randomized to early ACLR (n = 59) and patients randomized to optional delayed ACLR (n = 58, adjusted mean difference: -5 µm, 95% CI: [-118, 108]µm). However, the location-independent cartilage ChangeScore was greater in those treated with early ACLR than in patients treated with optional delayed ACLR (adjusted mean difference: 403 µm [119, 687]µm). As-treated analysis showed no between-group differences for the main outcome, while the location-independent cartilage ChangeScore was greater for patients treated with early (adjusted mean difference: 632 µm [268, 996]µm) or delayed ACLR (adjusted mean difference: 449 µm [108, 791]µm) than for patients treated with rehabilitation alone. CONCLUSIONS: In young active adults with acute ACL-injury, choice of treatment strategy for the injured ACL did not modify the magnitude of 5-year change in overall femorotibial cartilage thickness. TRIAL REGISTRATION: ISRCTN84752559.

Five-year followup of knee joint cartilage thickness changes after acute rupture of the anterior cruciate ligament.

OBJECTIVE: Anterior cruciate ligament (ACL) rupture involves an increased risk of osteoarthritis. The purpose of this study was to explore changes in cartilage thickness over 5 years after ACL rupture. METHODS: A total of 121 young active adults (ages 18-35 years; 26% women) from the Knee ACL, Nonsurgical versus Surgical Treatment (KANON) study, who had acute traumatic rupture of the ACL were studied. Sagittal magnetic resonance images were acquired within 4 weeks of ACL rupture (baseline) and at the 2-year and 5-year followup assessments. Medial and lateral femorotibial cartilage was segmented (with blinding to acquisition order), and the mean cartilage thickness was computed across 16 femorotibial subregions. Total femorotibial cartilage thickness change was the primary analytic focus. Maximal subregional mean cartilage thickness loss (ordered value 1 [OV1]) and gain (ordered value 16 [OV16]), independent of its specific location in individual knees, were the secondary analytic focus. RESULTS: Overall femorotibial cartilage thickness increased by 31 µm/year over 5 years (95% confidence interval 18, 44). The increase was similar in men and women and was significantly greater in those younger, as compared with those older, than the median age (25.3 years). The rate of total cartilage thickness change did not differ significantly between the first 2 years and the later 3 years. However, the maximal annualized subregional cartilage loss (OV1) and gain (OV16) were both significantly greater (P < 0.001 and P < 0.05, respectively) during the earlier interval than during the later interval (-115 versus -54 µm [OV1] and 116 versus 69 µm [OV16]). CONCLUSION: Cartilage thickening was observed over 5 years following ACL injury, particularly in the medial femorotibial compartment and in younger subjects. Major perturbations in cartilage homeostasis were seen over the first 2 years after ACL rupture, with simultaneous subregional thinning and thickening occurring within the same cartilage plate or compartment.