Keywords: Total Ankle Arthroplasty, Subtalar Joint Arthritis, Total Ankle Replacement
Introduction/Purpose: Ankle arthritis severely limits mobility and quality of life. Unlike hip and knee arthritis, which are mostly degenerative, 70–80% of ankle cases are post-traumatic. Injuries trigger cartilage damage, malalignment, and instability, often progressing to pain and surgery. Arthrodesis has long been the gold standard, providing pain relief but altering gait and increasing adjacent joint arthritis. Recent advances in implant design and technique have led to greater use of total ankle replacement (TAR), which may preserve motion and reduce secondary degeneration. However, non-stemmed TARs show risks of lucency and loosening, while stemmed intramedullary TARs improve stability but involve drilling near the subtalar joint, raising concerns of arthritis. This study evaluates 10+ year outcomes of subtalar joint degeneration following stemmed TAR.
Methods: This IRB-exempt study retrospectively reviewed 70 patients who underwent primary stemmed total ankle replacement (TAR) between January 2012 and December 2013. Patients with prior or simultaneous subtalar fusion were excluded. Minimum follow-up was 10 years. Sixteen patients (mean follow-up 11.5 years) met inclusion for radiographic analysis of subtalar osteoarthritis (OA) using the Stryker Inbone® implant, a fixed-bearing, three-component system with a stemmed tibial component. All procedures were performed by a single fellowship-trained foot and ankle surgeon following the manufacturer’s protocol.
Pre- and postoperative subtalar joint evaluations were completed with weight-bearing radiographs graded using the Kellgren-Lawrence Score (KLS). For patients who later underwent subtalar fusion, the most recent radiograph prior to fusion was analyzed. Demographics, radiographic data, and KLS were collected and classified by the authors. Mann-Whitney U tests compared continuous variables, and chi-square tests assessed categorical data and KLS progression. Significance was set at p < 0.05.
Results: Of 70 TARs, 16 patients met criteria for final analysis. Average of follow-up was 11.5 years. The cohort was 44% male, 44% left and 56% right TARs. Preoperatively, 69% had radiographic subtalar osteoarthritis (OA), most commonly KL grades 1–2. Postoperatively, 81% showed subtalar OA, with two patients progressing in KL grade, including one from 0 to 4 requiring revision for talar avascular necrosis. Subtalar joint (STJ) pain was reported in six patients (38%), two had radiographic progression. KL scores at final follow-up were higher in the STJ pain group (mean 2.17 vs. 1.0, p=0.0227). Six complications occurred: one high, two medium, three low grade. Four patients with complications had STJ pain, three requiring return to OR. Complications correlated significantly with postoperative STJ pain (p=0.0357).
Conclusion: In conclusion, at a mean follow-up of over 11 years, stemmed TAR demonstrated minimal radiographic progression of subtalar osteoarthritis, with no patients requiring STJ fusion to date.
Postoperative subtalar pain was observed but was more closely associated with implant-related complications than radiographic degeneration. These findings support the long-term safety of stemmed TAR with respect to subtalar joint preservation and emphasize the importance of monitoring for talar integrity and implant-related complications as primary drivers of clinical outcomes.
