To The Editor:
I read with interest the article "Conversion of Painful Ankle Arthrodesis to Total Ankle Arthroplasty" (2009;91:850-8) by Hintermann et al. and would like to offer the following comments and ask some questions of the authors.
A major concern regarding ankle arthroplasty continues to be the high rate of revision surgery. SooHoo et al., in a study of 480 ankle replacements performed during a ten-year study period, reported rates of major revision surgery after ankle replacement of 9% at one year and 23% at five years1.
Although the unconstrained mobile bearing ankle prosthesis has yielded good results in the short term, long-term results will need to be evaluated with respect to revision rates, especially for polyethylene wear, aseptic loosening, and loss of axial alignment.
I would like to have the authors respond to the following queries.
First, the authors reported persistent pain after arthroplasty in twenty-four of twenty-nine ankles. Did they localize the origin of pain? If the cause of pain was subtalar arthritis secondary to arthrodesis, arthroplasty would not have addressed this pathology.
Second, did the authors notice any difference in range of motion in non-weight-bearing and weight-bearing modes? Whatever range of ankle motion is provided by the implant is not necessarily utilized during steady-state walking. If 10° of dorsiflexion is not obtained during the middle portion of the stance phase, then, from a functional perspective, the gait adopted is similar to what is observed following an ankle arthrodesis2.
Third, keeping in mind the high rate of intraoperative malleolar fractures reported in the literature3, do the authors recommend prophylactic pinning in all cases?
Fourth, was medial ankle pain/impingement a prominent finding at the time of postoperative follow-up?