SLR - July 2018 - Rachel Ross
Comparison of Intermediate to Long-Term Outcomes of Total Ankle Arthroplasty in Ankles with Preoperative Varus, Valgus and Neutral Alignment
Reference: Lee GW, Wang SH, Lee KB. Comparison of Intermediate to Long-Term Outcomes of Total Ankle Arthroplasty in Ankles with Preoperative Varus, Valgus and Neutral Alignment. J Bone Joint Surg Am. 2018 May 16;100(10):835–842.
Scientific Literature Review
Reviewed By: Rachel Ross, DPM
Residency Program: Larkin Community Hospital, South Miami, Florida
Podiatric Relevance: Preoperative varus or valgus ankle alignment has been attributed to unsuccessful outcomes in total ankle arthroplasties (TAAs) and contraindicated if the malalignment exceeds 15 degrees. This study compares clinical and radiographic outcomes of TAA with varus (5–20 degrees), valgus (5–20 degrees) and neutral alignment (less than 5 degrees). The authors hypothesized the outcomes assessed would be satisfactory if neutral alignment of the ankle was achieved with the TAA.
Methods: From January 2005 to December 2012, 144 ankles meeting with minimum follow-up of 48 months after TAA and symptomatic end-stage osteoarthritis with no history of ankle arthrodesis were divided into varus, valgus and neutral groups. TAA was performed with a mobile-bearing HINTEGRA 3-component implant. If necessary, additional procedures were performed to achieve a stable, well-aligned ankle. Clinical evaluation consisted of: Ankle Osteoarthritis Scale (AOS) pain and disability score, American Orthopaedic Foot and Ankle Society (AOFAS) ankle-hindfoot score, Short Form (SF)-36 Physical Component Summary (PCS) score, Visual Analog Scale (VAS) pain score and sagittal ankle range of motion. Weightbearing ankle views preoperatively and one, three, six and 12 months after TAA were used to assess coronal plane alignment with the angle created between the anatomic axis of the tibia and the line perpendicular to the talar dome.
Results: After statistical analysis, there were no significant differences in the final AOS, AOFAS, SF-36 PCS and VAS between the groups. There was also no significant difference between final ankle dorsiflexion and plantarflexion in the varus, valgus and neutral ankle groups measuring 10.1, 11.3, 10.2 and 25.6, 25.2, 26.6 degrees, respectively. Radiographically, there was a significant difference (p = 0.010) between tibiotalar angle correction of varus group (median final angle of 3.2 degrees) compared to the neutral group (median final angle of 2.0 degrees); however, the median final angle was within neutral alignment. Concomitant procedures were greatest in the varus group (71.2 percent), followed by valgus group (55.9 percent), and lastly, the neutral group (39.2 percent). There was no significant difference between the groups for percutaneous Achilles tendon lengthening. For a mean follow-up of 7.3 years, the rate of implant survivorship was 97.7 percent in varus group, 90.9 percent in neutral group and 81.1 percent in the valgus group. Major complications, including deep infection, periprosthetic osteolysis (responsible for 22 of the 24 revision cases), technical error and posterior tibial nerve injury, had no significant intergroup difference.
Conclusions: The study suggests favorable clinical and radiographic outcomes in up to 20 degrees of preoperative coronal malalignment when neutral alignment is attained after TAA and any other necessary procedures. Although the final tibiotalar angle demonstrated a statistically significant difference in the varus group compared to the neutral group, the final angle was within the author’s designated neutral range. However, the upper limit of coronal alignment with satisfactory outcomes in more severe cases beyond 20 degrees remains in question.