SLR - September 2017 - Ryan D. Moss
Reference: Dekker TJ, Hamid KS, Easley ME, DeOrio JK, Nunley JA, Adams SB Jr. Ratio of Range of Motion of the Ankle and Surrounding Joints After Total Ankle Replacement: A Radiographic Cohort Study. J Bone Joint Surg Am. 2017 Apr 5; 99(7):576–582
Scientific Literature Review
Reviewed By: Ryan D. Moss, DPM
Residency Program: North Colorado Medical Center, Greeley, CO
Podiatric Relevance: Ankle arthritis is a common condition seen by foot and ankle surgeons. Oftentimes, conservative treatments fall short and surgical treatments are offered, such as ankle joint replacement. Although this procedure has been available for quite some time, past attempts at implant design were left with higher risks of failure and poor function. Recently, newly developed implants have improved the overall outcomes and functionality. This has allowed total ankle replacement to become a more popular procedure for end-stage ankle arthritis patients as opposed to arthrodesis. Total ankle replacements are continually being evaluated to determine long-term functionality and changes to the joints adjacent to the implants. This article examines objective radiographic findings of the functionality of adjacent joints after total ankle replacement and what this may indicate for these joints after the procedure.
Methods: The main purpose of this article was to radiographically evaluate the sagittal plane ankle range of motion available after a total ankle replacement. A level IV therapeutic prospective study was performed with all patients who had previously undergone total ankle replacement. A total of 197 patients met the inclusion criteria, consisting of 75 patients with INBONE, 52 with Salto Talaris prostheses and 70 with STAR prostheses. Range of motion of the ankle and adjacent joints was evaluated through weightbearing maximum dorsiflexion and plantarflexion sagittal plane radiographs. The total arc of motion was measured as well as the individual joint range of motion for the ankle joint and peritalar joints. There was a minimum of two years follow-up, with an average mean time of 42.9 ± 18.8 months from latest follow-up.
Results: Radiographic evaluation demonstrated an average range of motion with prosthesis of 25.9° ± 12.2°, which was significantly less than the average total motion arc of 37.6° ± 12.0°. The motion of the ankle accounted for 68 percent of total range of motion, and motion of the peritalar joints accounted for 32 percent. There was no significant difference among the three prostheses or when comparing fixed and mobile-bearing designs for both ranges of motion.
Conclusions: The study demonstrates that the motion at the ankle after total ankle replacement is approximately 12° less than the total motion that is clinically observed due to increased midfoot and subtalar motion. It also concluded that there were no significant differences between the range of motion found between prosthesis types, whether they are fixed or mobile-bearing in nature.