Keywords: Trabecular Metal Total Ankle, Transfibular Approach, Total Ankle Replacement
Introduction/Purpose: Multiple prior studies have documented inferior implant survivorship and increased complications in younger patient cohorts undergoing total ankle arthroplasty. However, no study has examined if lateral and anterior approach arthroplasties yield similar outcomes in this younger cohort. Lateral approach arthroplasty may be more durable in this population due to less bone resection that positions the implants in denser bone. This denser bone may better support the implants during a greater volume and higher level of patient activity that is expected in younger patients. The purpose of this study is to examine implant survivorship, radiographic outcomes, and patient-reported outcomes measures (PROM) at midterm follow up after transfibular total ankle arthroplasty (TAA) performed in patients younger than 55 years of age.
Methods: We retrospectively reviewed a group of prospectively followed patients who underwent primary transfibular TAA by a single surgeon from October 2012 to January 2020. Patients with minimum 5-year clinical and radiographic follow-up were analyzed. Patient demographics and perioperative data were collected. Pre- and postoperative patient-reported outcomes measures (PROMs) included: 12-item Short Form Health Survey (SF-12) physical (PCS) and mental (MCS) component scores, Ankle Osteoarthritis Scale (OAS), and Visual Analog Scale (VAS). Radiographic outcomes included alignment, ROM, and evaluation of periprosthetic cysts (lucency >2mm) utilizing a 12-zone system. Adverse events and reoperations were reported using the Canadian Orthopedic Foot and Ankle Society (COFAS) Reoperation Coding System (CROCS). Patients were divided into 2 groups for comparison based on age at time of surgery (Younger group, age <55, Older group, age ≥55).
Results: 251 ankles (237 patients) were included, younger cohort included 72 ankles (70 patients) with mean follow-up 6.9 years (range, 5-11), older cohort consisted of 179 ankles (166 patients) with mean follow-up of 7.0 (5-12) years. The younger group had a significantly higher primary diagnosis of post-traumatic arthritis (PTA, 83% vs. 61%) and history of previous ankle fracture fixation (84% vs. 68%, all p<0.05). There were no significant differences in concomitant procedures, rate of reoperation (40.3% vs. 33.0%), time to reoperation (21.7 vs. 27.4 months), implant revision (1.4% vs. 0%), or periprosthetic cysts (5.6% vs. 2.8%) between younger and older groups, respectively. Postoperative AOS Disability was significantly lower in the younger cohort (18.9 vs. 30.2, p=0.02), while AOS Pain, VAS, SF-12 PCS and MCS were similar.
Conclusion: Younger patients undergoing TAA had similar midterm implant survivorship, reoperation rate, and rate of periprosthetic radiolucency compared to patients 55 years of age or older. Lower postoperative disability scores suggest that the younger cohort was able to return to a lifestyle with higher functional demands. Overall, these results support transfibular TAA as a viable option in patients younger than 55 years- old, and highlight the need for longer term follow-up in this population.
