Does early reconstruction of the anterior cruciate ligament prevent further meniscal damage? Secondary analysis of randomized controlled trial

Abstract

Purpose: There is no low-risk-of-bias evidence to support the notion that surgical reconstruction of the anterior cruciate ligament (ACL) lowers the risk of future meniscal damage. Therefore, we investigated the loss of meniscal integrity on knee MRI over 5 years using data from the only randomized controlled trial in the field, comparing rehabilitation plus early ACL reconstruction vs a strategy of rehabilitation with optional delayed ACL reconstruction. Methods: We used longitudinal knee MRI data from 121 young active adults randomized to structured rehabilitation plus early ACL reconstruction (“early reconstruction” arm) or to structured rehabilitation with optional delayed ACL reconstruction (“optional delayed reconstruction” arm) (ISRCTN 84752559). Knee MRIs at baseline (after randomization but before treatment), and at the 5-year follow-up were read paired with knowledge of time sequence by one experienced musculoskeletal radiologist using the Anterior Cruciate Ligament Osteoarthritis Score (ACLOAS). Reader blinding to ACL-reconstructed knees at the 5-year follow-up was not feasible, but the reader was unaware of the specific study questions. Meniscal integrity was determined for all three segments of the medial and lateral meniscus. Worsening of meniscal integrity from baseline to the 5-year follow-up was defined as the occurrence of one or more of the following: i) an incident meniscal tear or progression of a pre-existing meniscal tear to involve another segment ii) incident loss of meniscus substance (due to maceration/destruction or surgical resection) iii) a new finding of status post meniscal repair, or iv) increase in medial or lateral meniscal body extrusion. With this dichotomized outcome, in an intention-to-treat analysis (ITT), we compared frequency of worsening of meniscal integrity on MRI in both treatment arms from baseline to 5 years using a logistic regression model. The model was adjusted for age, sex, and meniscal tears on MRI at baseline. For greater sensitivity and to evaluate severity of meniscal damage at 5 years, we also used a continuous outcome (integrity score) based on the sum of reclassified subregional meniscal grades from the ACLOAS (Table 1). For the integrity score, we used a zero-inflated Poisson regression model to compare severity of meniscal damage in an ITT analysis. This model was adjusted for age, sex, and baseline integrity score. Participants without baseline MRI readings were excluded from the analyses. Analyses were performed on knee level as well as on compartment level. Results: In the early reconstruction arm 62 participants were included, of which one was lost to follow-up. Four of the remaining 61 subjects had missing MRI readings at baseline. As a result, 57 subjects (mean [SD] age 26.6 [5.2] years, 81% men) remained for analysis. In the optional delayed reconstruction arm, 59 subjects (mean [SD] age 25.8 [4.7] years, 66% men) were included without loss to follow-up, with 30 subjects (51%) having had delayed ACL reconstruction within 5 years. Before treatment, the early reconstruction arm had more lateral meniscal damage detected on MRI (26% vs 7%), but medial meniscus damage was similar in both treatment arms (14% vs 15%). After 5 years, 19% of subjects in the early reconstruction arm had worsening of medial meniscal integrity vs 38% in the optional delayed reconstruction arm. For lateral meniscal integrity it was 38% vs 22%, respectively. We found a relative risk (RR) for worsening in meniscal integrity after 5 years on the knee level of 1.29 with a 95% confidence interval (CI) of 0.90-1.85 in the optional delayed reconstruction arm vs the early reconstruction arm. For worsening of medial meniscus integrity the RR was 1.95 (95% CI 1.06-3.57). For lateral meniscus the corresponding RR was 1.01 (95% CI 0.64-1.57). Relatively more subjects with an uninjured medial meniscus at baseline in the optional delayed reconstruction arm had worsening of medial meniscal integrity after 5 years compared to the early reconstruction arm (35% vs 12%). Meniscal worsening per segment is presented in Figure 1. Using meniscal integrity score as outcome, we found a 1.38 higher (severe) mean integrity score in the optional delayed reconstruction arm vs the early reconstruction arm (95% CI 1.07-1.78). For medial meniscus integrity, the corresponding model yielded a 1.80 higher mean score (95% CI 1.02-3.17), and for lateral meniscus integrity 1.04 (95% CI 0.63-1.75). Change in integrity score from baseline to the 5-year follow-up for the medial and the lateral meniscus for each treatment arm, respectively, is detailed in Figure 2. Conclusions: A strategy of early ACL reconstruction may reduce the risk of worsening of medial meniscus integrity following ACL injury. For the lateral meniscus, ACL reconstruction seems neither to be protective nor to increase the risk of future meniscal damage.View Large Image Figure ViewerDownload Hi-res image Download (PPT)View Large Image Figure ViewerDownload Hi-res image Download (PPT)