EARLY RESULTS WITH THE HINTEGRA ANKLE REPLACEMENT

Abstract

After catastrophic failure of first generation, joint replacement as treatment option for ankle osteoarthritis is undergoing a revival with improved second generation designs. Short to mid-term results reportedly equal those of ankle arthrodesis in terms of complications and revision, but preserving joint motion and protecting neighbouring midfoot joints from overuse and consecutive osteoarthritis. However, most reports derive from developers centres excluding the learning curve. We present clinical results and subjective outcome of an initial patient series undergoing ankle replacement in an independent centre.

From January 2004 to January 2008 a Hintegra^® prosthesis was implanted in 39 consecutive patients (41 ankles), average age 60.7 years (range 36.6–85.0), 13 males and 25 females. Repeated clinical follow up was done for an average of 2.2 years (range 0.5–4.3). All patients whose operation had been more than 0.7 years before were sent the FAOS (Foot and Ankle Outcome Score) in order to record the subjective outcome. Pre-operative diagnoses were posttraumatic osteoarthritis in 26 cases (63.4%), primary osteoarthritis in 9 cases (22%) and rheumatoid arthritis in 6 cases (14.6%).

Clinical examination did not show significant improvement of mean range of motion, dorsiflexion and plantarflexion compared with the preoperative status. The change in motion highly correlated with the preoperative mobility (r=0,8; p< 0.001): patients with the largest preoperative range of motion were the ones to lose most mobility, whereas patients with low preoperative motion gained mobility. About 60% of the patients achieved 25° to 30° total range of motion regardless of their preoperative mobility. Early postoperative complications occurred in 14 patients (34.1%). In all five subclasses of the FAOS a significant improvement was achieved within the observation period. Reduction of pain had the greatest impact on the improvement of quality of life, whereas change in mobility did not have any influence.

Joint replacement is a valuable treatment option for ankle osteoarthritis. There are however a series of early complications and restrictions of subjective outcome a surgeon has to be aware of when selecting an individual patient for ankle replacement. Further studies are needed to detect in which cases arthrodesis or prosthesis is preferable.