Abstract
Introduction
Periprosthetic cyst formation following ankle replacement, requiring revision surgery, has previously been reported. The exact pathogenesis of cyst formation is unclear but considered to be due to a combination of biological and mechanical factors. Our objective was to review the incidence of periprosthetic cyst formation following Mobility ankle replacement and their outcome.
Patients and methods
We reviewed all the Mobility ankle replacements performed by the senior author from Oct 2005 till May 2012. Serial radiographs were reviewed to identify the presence of cystic lesions in the tibia or the talus.
Results
124 Mobility ankle replacements were performed in 116 patients during our study period. Average age was 65 years (22 to 88) with male to female ratio of 2:1. Average follow-up was 32 months (7 to 73). Radiographic review of the most recent available radiograph showed cystic changes in the distal tibia in 10 patients (8%). One patient had cystic appearance pre-operatively which was not found to be progressive after replacement.
Seven patients were asymptomatic. Three patients presented with ankle pain, which was thought to be due the cyst. One of the symptomatic patients had undergone revision of tibial component and bone grafting of the cyst 32 months after primary surgery. The second patient is awaiting surgery for exploration and possible bone graft (40 months after primary surgery). The 3rd patient is awaiting CT scan for further evaluation of the cyst.
Conclusion
Our study shows that cystic changes were present in 8% of TAR at medium term review. 70% (7 patients) were asymptomatic and 30% required intervention for being symptomatic. Regular review of the TAR patients is essential to identify the patients who develop cyst formation.
