Purpose: The incidence of anterior cruciate ligament reconstruction (ACLR) to replace a ruptured ACL is increasing globally. Many individuals after ACLR have prolonged knee symptoms, reduced function, weight gain, and early-onset post-traumatic osteoarthritis (OA). Individuals after ACLR report poorer quality of life (QOL) than their uninjured peers (short- and long-term), Knee-related QOL appears to be more impaired than health-related QOL after ACL tear. However, few studies have evaluated health-related QOL, particularly beyond the acute recovery period when health-related QOL may deteriorate. Few studies have evaluated modifiable risk factors associated with QOL after ACL tear, with most focusing on established risk factors for OA such as age, sex, and obesity. Given QOL is a key driver of individual, societal, and healthcare system burden, identifying of modifiable risk factors associated with knee- and health-related QOL is needed to develop targeted secondary prevention strategies to avoid deterioration in QOL after ACLR. The objective of this secondary analysis of data from two international cohorts is to assess the relative contribution of potentially modifiable characteristics (knee pain, self-reported function, early OA features on MRI) to knee- and health-related QOL after ACLR.
Methods: Data from two cohort studies (1-The Alberta Youth Prevention of Early Osteoarthritis Cohort (PrE-OA; Calgary, Canada) and 2-Knee Osteoarthritis after Anterior cruciate Ligament injury Assessment cohort (KOALA; Melbourne, Australia) were combined for a cross-sectional analysis. Individual participant data was included if participants had (i) sustained a complete ACL rupture 3-11 years prior (with or without ACLR); and (ii) had patient-reported outcome and index knee MRI data collected between 3 and 11 years after ACL tear. Outcomes included knee-related QOL (ACL Quality of Life Questionnaire; ACL-QOL) and health-related QOL (European Quality of Life Five Dimensions; EQ-5D). ACL-QOL and EQ-5D item scores were transformed to a 0-100 scale and averaged to produce a total score (higher scores indicating a better outcome). Exposure variables were (i) knee pain (Knee Injury and Osteoarthritis Outcome Score subscale; KOOS-Pain), (ii) self-reported knee function (KOOS-Function in sport and recreation subscale), and (iii) any knee cartilage lesion on MRI. The presence of any cartilage lesion was defined as any lesion with a size ≥grade 1 in the tibiofemoral or patellofemoral compartment (as per the MRI OA Knee Scoring System). Descriptive statistics for exposure and outcomes variables by cohort were summarized for all participants characteristics. Generalised linear models assessed the association between the exposure variables and QOL outcomes, adjusting for clustering between sites. Unknown BMI measurements were imputed using multiple chained equations. Injury type (ACL with or without meniscal injury), subsequent intra-articular knee injuries, and body mass index were included as covariates.
Results: Data from 126 participants were included. KOALA participants (n=76) were a median [range] 5.4 [4.9-9.6] years after ACL injury, while PrE-OA participants (n=50) were 6.6 [4.1-11.6] years after ACL injury. All participants underwent ACLR, but there was a greater proportion of concomitant meniscal injuries and meniscal surgery in the PrE-OA cohort (70%) compared to the KOALA cohort (46%). Participant characteristics, exposure and outcomes variables are summarized in Table 1. MRI cartilage lesions were not associated with ACL-QOL or EQ-5D scores (Table 2). For every 1-point improvement in KOOS-Function, the ACL-QOL improved by 0.37 (95% CI: 0.17, 0.57) points. For every 1-point improvement in KOOS-Pain, the EQ-5D improved by 0.38 (95% CI: 0.08, 0.69).
Conclusions: The results of this study suggest self-reported pain and function are more relevant for determining knee-related and health-related QOL than structural features of joint degeneration after ACLR. Knee-related QOL appears to be influenced by knee function and pain, while health-related QOL was not associated with knee function but was associated with knee pain. Future secondary prevention interventions which address knee function and pain should be developed and evaluated to determine the effect on QOL outcomes.
Table 1Participant characteristics of the KOALA and PrE-OA cohorts
| KOALA (n=76) | PrE-OA (n=50) | All (n=126) | |
|---|---|---|---|
| Participant characteristics | |||
| Sex, no. (%) male | 48 (63) | 14 (28) | 62 (49) |
| Age, median (range) years | 32 (14) | 23 (3) | 26 (12) |
| BMI, median (range) kg/m2 | 25.8 (20.1-35.0) | 24.7 (19.7-38.9) | 25.2 (19.7-38.9) |
| Subsequent injuries ∗ , no. (%)Subsequent injury may include any new or recurrent intra-articular knee injury to the index or contralateral limb between the initial ACL injury/ACLR and 3-11-year assessment. Injury types may include ACL graft rupture, meniscal injury, collateral or posterior cruciate ligament injury, chondral injury (with or without surgical intervention) | 14 (18) | 21 (42) | 35 (28) |
| QOL outcomes | |||
| ACL-QoL total, median (range) | 86 (33-97) | 79 (24-100) | 82 (24-100) |
| EQ-5D index, median (range) | 100 (73-100) | 84 (0-100) | 100 (0-100) |
| Explanatory variables | |||
| KOOS-Pain, median (range) | 97 (47-100) | 94 (53-100) | 94 (47-100) |
| KOOS-Sport, median (range) | 90 (20-100) | 94 (47-100) | 93 (20-100) |
| Any cartilage lesion, no (%) | 60 (79) | 35 (70) | 95 (75) |
* Subsequent injury may include any new or recurrent intra-articular knee injury to the index or contralateral limb between the initial ACL injury/ACLR and 3-11-year assessment. Injury types may include ACL graft rupture, meniscal injury, collateral or posterior cruciate ligament injury, chondral injury (with or without surgical intervention)
Tabled
1Regression estimated scores1: contribution of clinical characteristics to QOL
| ACL-QOL | EQ-5D index | |
|---|---|---|
| Any cartilage lesion (ref: no lesion) | -1.20 (-5.13,2.73) | 1.83 (-2.03, 5.69) |
| KOOS-Pain (continuous score) | 0.49 (-0.00, 0.99) | 0.38 (0.08,0.69) |
| KOOS-Function (continuous score) | 0.37 (0.17, 0.57) | -0.08 (-0.26, 0.09) |
| Concomitant meniscal injury (ref: isolated injury) | -5.04 (-7.92, -2.16) | -3.72 (-4.49,-2.96) |
| Subsequent injury (ref: no subsequent injury) | -7.00 (-7.40, 6.60) | 0.29 (-3.78, 4.36) |
| Body mass index (continuous score) | -0.27 (-0.71, 0.17) | 0.10 (-0.40,0.60) |
∼ Values are estimates derived from the generalized linear model with a binary family and probit link (95% confidence interval). Scores are indices measured as percentages and presented as such. Bold values indicate a statistically significant association (p<0.05).
∗ Estimates represent the adjusted mean difference in ACL-QoL and/or EQ-5D between categories for dichotomous variables (any cartilage lesion, concomitant injury, subsequent injury).
∗∗ Estimates represent the adjusted mean change in ACL-QoL and/or EQ-5D given a 1 unit increase in the predictor variable for continuous variables (KOOS-Function and KOOS-Pain).
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