Total Ankle Arthroplasty for Posttraumatic Fracture Versus Primary Osteoarthritis: An Analysis of Complications, Revisions, and Prosthesis Survival.

BACKGROUND

Most outcome studies of total ankle arthroplasty (TAA) do not discriminate by arthritis etiology. The primary purpose of this study was to compare the complications of TAA between posttraumatic fracture osteoarthritis (fracture PTOA) and primary osteoarthritis (POA).

METHODS

Ninety-nine patients who underwent TAA were retrospectively evaluated with a mean follow-up of 3.2 years (range 2 to 7.6 years). 44 patients (44%) had a diagnosis of POA while 55 patients (56%) had a diagnosis of fracture PTOA (40 malleolar fractures [73%], 14 pilon fractures[26%], and 1 talar fracture [1%]). Patient demographics, preoperative coronal plane alignment, postoperative complications, and revision surgery data were collected. Categorical variables were compared with chi square and Fisher exact tests and means with the Student t -test. Survival was assessed with Kaplan-Meier and log-rank analyses.

RESULTS

A higher overall complication rate was associated with fracture PTOA (53%) compared with POA (30%) ( P = 0.04). No difference was observed in rates of any specific complication by etiology. Survival, defined as revision surgery with TAA prosthesis retention, was comparable between POA (91%) and fracture PTOA (87%) ( P = 0.54). When defined as failure requiring prosthesis explant, POA demonstrated significantly greater survival (100%) as compared with fracture PTOA (89%) ( P = 0.03). A higher rate of talar implant subsidence and loosening was noted in TAA with prior pilon (29%) as compared to malleolar fractures (8%) that was not statistically significant ( P = 0.07). Fracture PTOA was associated with preoperative valgus deformity ( P = 0.04). Compared with varus and normal alignment, preoperative valgus deformity was associated with the need for any revision surgery ( P = 0.01) and prosthesis explant ( P = 0.02).

CONCLUSIONS

Compared with POA, fracture PTOA was associated with a markedly higher complication rate after TAA and was at higher risk of failure requiring prosthesis explant. Fracture PTOA was markedly associated with preoperative valgus malalignment, an identified risk factor in this series for revision surgery and prosthesis explant. Pilon fractures may represent a group at risk of complications related to talar implant subsidence and loosening compared with malleolar fractures and thus warrants additional investigation.

LEVEL OF EVIDENCE: III.