Summary

This study evaluated predictive factors of post-traumatic radiographic osteoarthritis (OA) in the medial, lateral, and patellofemoral compartments, within a large randomized clinical trial at 5-years post-ACL reconstruction. Varus alignment and medial meniscectomy increase risk of medial OA. PT graft, lateral meniscectomy, meniscus repair, and chondral damage increase the risk of lateral OA.

Abstract

Purpose

To evaluate predictive factors of post-traumatic radiographic osteoarthritis (OA) in the medial, lateral, and patellofemoral compartments, within a randomized clinical trial at 5-years post-ACL reconstruction.

Methods

Three-hundred-and-thirty patients (14–50 years) were randomized intra-operatively to ACL reconstruction (ACLR) with patellar tendon (PT), single-bundle semitendinosus/gracilis tendon (HT), or double-bundle semitendinosus/gracilis tendon (DB) autografts. Clinical and quality-of-life-outcomes were previously published.

Baseline, 2- and 5-year standardized radiographs (bilateral P-A weightbearing, 45 degrees flexion; lateral 40-45 degrees, and bilateral skyline patella views) were assessed for radiographic OA in the medial, lateral, and patellofemoral compartments, using the International Knee Documentation Committee (IKDC) scale. Presence of radiographic OA was defined by IKDC Abnormal or Severely Abnormal grades. An independent fellowship-trained orthopaedic surgeon blinded to all outcomes assessed the radiographs.

Primary outcomes included radiographic OA and Anterior Cruciate Ligament Quality-of-Life (ACL-QOL) scores. Five-year medial, lateral, and patellofemoral radiographic OA were the respective dependent outcome variables in three multi-variable logistic regressions. Independent predictor variables included: age, sex, knee alignment, clinical stability (Lachman, pivot shift tests), meniscal treatment, chondral condition at surgery, graft type, graft failure, re-injury, and secondary surgery. Bivariate logistic regressions were performed for each predictor; individual predictor variables with p<0.1 were added into the multi-variable model. Odds ratios and 95% Confidence Intervals (95%CI) were reported. An ANCOVA investigated the association of radiographic OA in each compartment and ACL-QOL scores at 5-years.

Results

Five-year IKDC grades for radiographic OA were available for 302 patients (91.5%). Thirty-five patients (10.6%) had radiographic OA in the medial compartment. Varus alignment, meniscectomy, chondral damage, age>35, and male sex were identified as individual predictors. Only medial meniscectomy and varus knee alignment were statistically significant predictors of medial OA in the multi-variable model, with odds ratios of 5.8 (95%CI 2.7–12.6, p<0.01) and 2.4 (95%CI 1.1–5.1; p=0.03), respectively.

Sixty-seven patients (20.3%) had radiographic OA in the lateral compartment. Graft type, pivot shift, valgus alignment, meniscectomy, meniscal repair, and chondral damage were identified as individual predictors. Only PT graft, lateral meniscectomy, lateral meniscus repair, and lateral chondral damage were statistically significant predictors of lateral OA in the multi-variable model, with odds ratios of 2.4 (95%CI 1.2–4.8, p=0.02), 2.6 (95%CI 1.3–5.2, p= 0.01), 3.3 (95%CI 1.5–7.4, p= 0.01), and 2.0 (95%CI 1.0–3.9, p=0.04), respectively.

Only 9 patients (2.7%) had patellofemoral OA; insufficient to progress to a multi-variable model. Bivariate analyses showed patellofemoral chondral damage as the only significant predictor of OA at 5-years (odds ratio of 5.7; 95%CI 1.5–21.8, p=0.01).

Graft failure, traumatic re-injury, and secondary surgery did not predict radiographic OA at 5-years in any compartment. No significant associations were shown between 5-year ACL-QOL scores and presence of medial, lateral, or patellofemoral OA.

Conclusions

Varus alignment and medial meniscectomy at ACLR significantly increase the risk of developing medial OA. PT graft, and meniscectomy, meniscus repair, and presence of chondral damage in the lateral compartment significantly increase the risk of developing lateral OA. Higher proportions of OA cases would increase the confidence in these associations.