The Clinical Radiographic Incidence of Posttraumatic Osteoarthritis 10 Years After Anterior Cruciate Ligament Reconstruction: Data From the MOON Nested Cohort

Abstract

Background: The incidence of posttraumatic osteoarthritis (PTOA) based on clinical radiographic grading criteria at 10 years after anterior cruciate ligament (ACL) reconstruction (ACLR) has not been well-defined in a prospective cohort of young athletic patients.

Hypothesis: Among young athletic patients, there is a high incidence of clinical radiographic PTOA at 10 years after ACLR. Additionally, there is a significant difference in clinical radiographic osteoarthritis (OA) changes (joint space narrowing and osteophyte formation) between ACL-reconstructed and contralateral knees at 10 years.

Study design: Case series; Level of evidence, 4.

Methods: The first 146 patients in an ongoing nested cohort study of the Multicenter Orthopaedic Outcomes Network (MOON) prospective cohort presented for a minimum 10-year follow-up. Included patients had a sports-related ACL injury, were aged <33 years at the time of ACLR, had no history of ipsilateral or contralateral knee surgery, and did not undergo revision ACLR before follow-up. Bilateral knee metatarsophalangeal view radiographs were obtained and graded according to International Knee Documentation Committee (IKDC), Osteoarthritis Research Society International (OARSI), and modified Kellgren-Lawrence (KL) criteria by 2 blinded reviewers. The incidence and severity of ipsilateral and contralateral radiographic OA were determined among patients without a contralateral ACL injury before 10-year follow-up (N = 133).

Results: Interrater reliability was substantial for the IKDC (Gwet Agreement Coefficient [AC] 1 = 0.71), moderate for the KL (0.48), and almost perfect for the OARSI (0.84) grading systems. Among patients with a contralateral radiographically normal knee, the 10-year incidence of clinical radiographic PTOA after ACLR was 37% as defined by osteophytes and 23% as defined by joint space narrowing. The maximum side-to-side difference in the OARSI osteophyte grade in the medial or lateral compartment was 0 in 65% of patients, 1 in 20%, and ≥2 in 15%. The maximum side-to-side difference in the OARSI joint space narrowing grade was 0 in 77% of patients, 1 in 19%, and ≥2 in 4%.

Conclusion: In young active patients, the 10-year incidence of clinical radiographic PTOA after ACLR was 37% as defined by osteophytes and 23% as defined by joint space narrowing. The mean difference in the degree of osteophyte formation (≤1 grade in 85%) and joint space narrowing (≤1 grade in 96%) between the ACL-reconstructed and contralateral knees was small.

Registration: NCT02717559 (ClinicalTrials.gov identifier).

Keywords: ACL reconstruction; joint space narrowing; posttraumatic osteoarthritis; radiographic osteoarthritis; weightbearing radiographs.

Figures

Figure 1.

STROBE (Strengthening the Reporting of Observational Studies in Epidemiology) diagram. ACL, anterior cruciate ligament. OA, osteoarthritis.

Figure 2.

Representative examples of IKDC osteoarthritis grades at 10 years after ACL reconstruction.

Figure 3.

Representative examples of modified Kellgren-Lawrence knee osteoarthritis grades at 10 years after ACL reconstruction.

Figure 4.

Representative examples of maximum side to side differences in OARSI joint space narrowing (JSN) grade in either the medial or lateral tibiofemoral compartment at 10 years after unilateral ACL reconstruction. Joint space narrowing is indicated by the white arrows.

Figure 5.

Representative examples of maximum side to side differences in OARSI osteophyte grade (tibial grade plus femoral grade) in either the medial or lateral tibiofemoral compartment at 10 years after unilateral ACL reconstruction. Tibial and femoral marginal osteophytes are indicated by the white arrows. Femoral notch and tibial intercondylar eminence osteophytes are not considered in OARSI osteophyte grading.