Total Ankle Replacement Provides Symmetrical Postoperative Kinematics: A Biplane Fluoroscopy Imaging Study

Abstract

Background: In vivo measurements of tibiotalar and subtalar joint motion following TAR are unavailable. Using biplane fluoroscopy, we tested the hypothesis that the prosthetic tibiotalar joint and adjacent subtalar joint would demonstrate kinematic and range of motion differences compared to the contralateral untreated limb, and control participants. Methods: Six patients of 41 identified candidates that all underwent unilateral Zimmer TAR (5.4 ± 1.9 years prior) and 6 control participants were imaged with biplane fluoroscopy during overground walking and a double heel-rise activity. Computed tomography scans were acquired; images were segmented and processed to serve as input for model-based tracking of the biplane fluoroscopy data. Measurements included tibiotalar and subtalar kinematics for the TAR, untreated contralateral, and control limbs. Statistical parametric mapping quantified differences in kinematics throughout overground walking and the double heel-rise activity. Results: Patients with this TAR performed walking and heel-rise activities symmetrically with no significant kinematic differences at the tibiotalar and subtalar joints between limbs. Compared to control participants, patients exhibited reduced dorsi/plantarflexion range of motion that corresponded to decreased peak dorsiflexion, but only in the late stance phase of walking. This reduction in tibiotalar dorsi/plantarflexion range of motion in the TAR group became more apparent with double heel-rise activity. Conclusion: Patients with a Zimmer TAR had symmetric kinematics during activities of walking and double heel-rise, but they did exhibit minor compensations in tibiotalar kinematics as compared to controls. Clinical Relevance: The lack of significant kinematic compensation at the subtalar joint may explain why secondary subtalar osteoarthritis is reported as being relatively uncommon in patients with some TAR designs.

Decreased Mechanical Work Demand in the Chopart Joint After Total Ankle Replacement

“…25,36 To overcome these challenges, methods using biplanar videoradiography have been used to provide more accurate measures of foot joint motion, which can be difficult to discern with skin-mounted markers. 25,36 Recently, Lenz et al 24 used biplanar videoradiography to capture postoperatively the kinematics at the prosthetic ankle joint as well as the adjacent subtalar joint. 24 They found symmetrical ankle and subtalar kinematics between operated and nonoperated limbs after TAR during walking and double heel-rise tasks.…”

“…25,36 Recently, Lenz et al 24 used biplanar videoradiography to capture postoperatively the kinematics at the prosthetic ankle joint as well as the adjacent subtalar joint. 24 They found symmetrical ankle and subtalar kinematics between operated and nonoperated limbs after TAR during walking and double heel-rise tasks. However, the invasive/ionizing nature of these alternative methods precludes their use in routine clinical analysis.…”

Discrepancies Between Intraoperative and Postoperative Ankle Motion Measured for Anterior-Approach Total Ankle Arthroplasty

“…Preoperative ROM radiographs were obtained and saved for patients undergoing primary TAA, and postoperative ROM radiographs were ordered at a minimum of 6 months after the index surgery following prior reports indicating the absence of significant improvements in ankle ROM 6 months after surgery. 1 The mean time from surgery to postoperative ROM radiographs was 11.4 months (range, [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25].…”

“…One of the proposed benefits of total ankle arthroplasty (TAA), when compared to ankle fusion, is the preservation of ankle range of motion (ROM). 9 Literature indicates that TAA can closely replicate normal ankle joint motion 18,24 and minimize stress on adjacent joints. 3,12 Increased ankle motion following TAA may improve the quality of life, as evidenced by patient-reported outcome measures.…”

Range of Motion After Total Ankle Replacement: Are We Just Stuck?

“…Finally, muscle forces act on the ankle-subtalar joint complex and not on the ankle in isolation, so future investigations may benefit from a more comprehensive functional comparison of the preoperative arthritic ankle and TAA at follow-up through study of tibiotalar and hindfoot kinematics using CT-acquired segmented images for model-based tracking of biplanar fluoroscopic data. 8…”