Five‐Year Followup of Knee Joint Cartilage Thickness Changes After Acute Rupture of the Anterior Cruciate Ligament

Abstract

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 m/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 m [OV1] and 116 versus 69 m [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.Anterior cruciate ligament (ACL) rupture is a serious and common knee injury that mainly affects young and physically active individuals (1,2). ACL rupture commonly results in joint instability, compromised knee function, and reduced physical activity and kneerelated quality of life, with lost wages, loss of productivity, and disability (2,3). Individuals with a history of knee injury were shown to be 7.4 times more likely to develop knee osteoarthritis (OA) than those without an injury, and knee injury has been estimated to be the cause of a substantial portion of all knee OA (4,5). ACL rupture ISRCTN: 84752559.

Twenty-Year Outcomes of a Longitudinal Prospective Evaluation of Isolated Endoscopic Anterior Cruciate Ligament Reconstruction With Patellar Tendon Autografts

“…This is in contrast with other studies looking at the progression of OA in ACL-reconstructed knees, where higher levels of more severe degenerative changes are seen, with some as high as 20% at 10 years with moderate to severe radiographic changes. 1,15,29 The presence of other injuries in the knee such as chondral injuries or meniscal tears may increase the rate and degree 11,20,21,28,31,32,39 and this may account for the lower incidence reported in our series compared with others. It should be remembered that the cohort of patients in this study would now be a mean age of 45 years.…”

“…15,29 In this series, radiological degenerative change was present in 27% of patients at 5 years, 51% at 15 years, and 61% at 20 years. However, the proportion of patients with moderate to severe changes was low; only 20% of patients had grade C (up to 50% joint space narrowing) changes at 20 years, and there were no grade D changes.…”

Comparison of radiographic joint space width and magnetic resonance imaging for prediction of knee replacement: A longitudinal case-control study from the Osteoarthritis Initiative

“…The current study provides evidence that not only cartilage loss, but also subregional thickness gain was greater over 2 years prior to knee replacement than in matched controls. Greater simultaneous subregional cartilage thickness gain and loss also have been recently reported after anterior cruciate ligament injury [25] and may describe a state of cartilage “perturbation”, during which cartilage loss in some locations is accompanied by cartilage swelling or hypertrophy in others. Such observations are unique to the use of location-independent MRI and are obscured when only region-specific measurements are performed by MRI or radiography [25].…”

“…In addition, novel summary measures of subregional cartilage thickness change were computed [25]: these included the total subregional cartilage thinning score; i.e. the sum of all negative cartilage thickness changes across as many of the 16 subregions in which cartilage loss occurred in each knee), the total subregional cartilage thickening score (the sum of all positive cartilage thickness changes), and the total subregional cartilage change score (the sum or all 16 subregional cartilage thickness changes independent of direction).…”

Anterior cruciate ligament reconstruction and knee osteoarthritis

“…These changes, as well as changes in gene expression post impact injury could trigger cartilage catabolism and potentially initiate the process of cartilage degeneration[11,13]. An indirect sign that supports this theory is the significant cartilage thickening seen in MRIs 5 years following an ACL tear, that can be attributed to abnormal swelling due to disruption of cartilaginous matrix integrity[14]. However, the exact role of cartilage thickness change after ACL injury is yet to be determined.…”