Progression of medial meniscal extrusion following anterior cruciate ligament reconstruction correlates with graft diameter: a retrospective longitudinal study.

BACKGROUND

Posttraumatic osteoarthritis (PTOA), a subtype of knee osteoarthritis (OA), develops following intra-articular injuries such as fractures, ligament tears, or meniscal damage, accounting for approximately 12% of symptomatic knee OA. Notably, 87% of patients with anterior cruciate ligament (ACL) injuries are expected to develop PTOA, and there is currently no established method to prevent its progression. While ACL reconstruction (ACL-R) restores joint stability, it does not necessarily halt PTOA development. Previous MRI-based studies have identified medial meniscal extrusion (MME) and medial tibial osteophyte (MTO) formation as early indicators of PTOA. Moreover, ACL-R can trigger intra-articular hematoma and inflammation, especially due to the drilling of bone tunnels for graft insertion. Larger graft diameters may cause more joint trauma; however, their association with early PTOA changes remains unclear. This study aimed to investigate the relationship between graft diameter and early PTOA progression as observed on MRI.

METHODS

This retrospective cohort study included 42 patients (30 males, 12 females) who underwent arthroscopic ACL-R by a single surgeon. MRI scans were obtained preoperatively and once postoperatively, between 5 and 12 months after surgery. Graft diameter was measured at both femoral and tibial tunnel sites using a cylindrical sizer, and the average value was used for analysis. PTOA changes were assessed based on progression of MME and osteophyte formation. Patients were categorized into larger and smaller graft groups using the cohort's median graft diameter (9.25 mm) as the cutoff.

RESULTS

Graft diameter significantly correlated with MME progression (ΔMME: r = 0.48, p = 0.001) and MTO progression (ΔMTO: r = 0.31, p = 0.048). ΔMME also strongly correlated with ΔMTO (r = 0.67, p < 0.001), but not with medial femoral osteophyte (ΔMFO: r = 0.23, p = 0.15) or lateral compartment changes. The larger graft group exhibited significantly greater ΔMME (p = 0.005) and ΔMTO (p = 0.03) compared to the smaller graft group.

CONCLUSION

Larger graft diameters were associated with greater early progression of MME and MTO following ACL-R. These findings suggest a possible mechanical or inflammatory contribution to early PTOA development after reconstruction.