Radiologic Progression of Early-Stage Ankle Osteoarthritis: A Mean 12-Year Follow-up Observational Study.

Abstract

Background: The natural history of early-stage ankle osteoarthritis (OA) remains poorly defined, and the long-term outcomes of nonoperative management are unclear. This study investigated long-term Takakura stage progression and associated risk factors in early-stage ankle OA managed nonoperatively.

Methods: In this study, 57 patients (89 ankles) with Takakura stage I-IIIA ankle OA who were followed up for a mean of 12.1 years were retrospectively reviewed. At the first and final visits, radiographic parameters including Takakura stage, mechanical axis deviation (MAD), hindfoot alignment angle (HAA), hindfoot moment arm (HMA), tibial articular surface angle (TAS), tibial lateral surface angle (TLS), and talar tilt angle (TT) were measured. Clinical outcomes were assessed using the Foot Function Index (FFI) and visual analog scale (VAS). Risk factors for stage progression were evaluated using multivariable logistic regression.

Results: Of the 89 ankles, 50 (56.2%) showed no Takakura stage progression, 35 (39.3%) progressed by 1 stage, and 4 (4.5%) progressed by 2 stages. Among ankles classified as stage IIIA at baseline, progression to stage IIIB occurred more frequently in those with hindfoot varus deformity (p = 0.023). In the progression group, HMA, HAA, and TT increased (all p < 0.001), whereas TAS and TLS decreased (p < 0.001 and p = 0.045, respectively). In multivariable analysis, HAA (odds ratio [OR], 2.49; p = 0.076), HMA (OR, 2.09; p = 0.085), and TT (OR, 1.38; p = 0.064) showed statistical trends toward association with progression, whereas TAS, TLS, MAD, initial stage, sex, age, and body mass index (BMI) were not significant predictors. The VAS score improved in the no-progression group (p = 0.008) and worsened in the progression group (p = 0.006), while changes in FFI were not significant.

Conclusions: In this 12.1-year follow-up observational study of early-stage ankle OA, no radiographic progression was observed in 56.2% of ankles, 1-stage progression in 39.3%, and 2-stage progression in 4.5%. Progression from stage IIIA to stage IIIB occurred more frequently in ankles with hindfoot varus. Lower limb alignment and clinical factors (sex, age, and BMI) were not significantly associated with OA progression.