SLR - August 2014 - Andre Ross

Comparison of Gait after Total Ankle Arthroplasty and Ankle Arthrodesis

Reference:  Flavin R, Coleman SC, Tenenbaum S, Brodsky JW. Comparison of Gait after Total Ankle Arthroplasty and Ankle Arthrodesis. Foot and Ankle Int. 34(10) 1340-1348. 

Scientific Literature Review

Reviewed By: Andre D. Ross
Program: Hoboken University Medical Center, Hoboken, NJ. 

Podiatric Relevance: Total ankle arthroplasty is a rapidly developing trend in the field of foot and ankle surgery. Very important are studies aimed at tracking outcomes of these procedures for this very reason. Early generation ankle implants showed inconsistent short to intermediate follow up, however recently with development of two and three component systems, more reliable intermediate to long term studies are available. These tools aid us in our decision making with the ultimate goal being decreasing pain while preserving function. Patient selection proves critical in evaluating candidates for TAA as ankle implant lifespan is less than that of other joint implants. The alternative, ankle arthrodesis, has already been demonstrated effective, however leads to further degenerative changes to adjacent joints as well as a significant reduction in normal anatomic function of the affected extremity. The authors of this study aim to provide a comprehensive prospective analysis demonstrating gait differences between the two groups that could translate into long lasting advantages and disadvantages for our patients in the future.

Methods: Twenty-eight patients with end stage ankle arthritis participated in the two intervention groups, of which fourteen received a total ankle arthroplasty and fourteen an ankle arthrodesis. The two groups were matched based on age, gender, diagnosis. Fourteen additional healthy volunteers comprised the control group.  All patients in the TAA implant group received the Scandanavian Total Ankle Replacement prosthesis (STAR). Exclusion criteria for the TAA were as follows: patient less that 40 years, coronal plane deformity greater than 10 degrees, and patients who requested ankle arthrodesis based on informed consent. Ankle radiographs were measured for coronal and sagittal tibiotalar tibiotalar angles preoperatively and one year postoperatively. The intervention group were subjected to 3-dimensional gait analysis preoperatively and one year after surgery.  A segmented foot model for data collection was used and eleven 6-mm markers were used on each limb. Foot marker placement included the hallux; first and fifth metatarsal heads and bases; and lateral, medial, and posterior calcaneus. To define the leg, markers were placed on the lateral and medial malleoli of the tibia and fibula, as well as the tibial tuberosity. Neutral stance was calculated using statistical data gathered from the markers. This data was then used in the walking trials which consisted of subjects walking multiple times across a 10-m segment at a self selected pace. A minimum of 20 strides were used for statistical analysis. Temporospatial parameters included velocity, cadence, and stride length. Kinematic parameters included sagittal peak power and maximum sagittal and coronal moments. Another parameter included the center of pressure (CoP) progression which was calculated relative to the entire stance phase and both rockers of the foot. Vertical ground reactive forces (vGRF) were calculated preoperatively and and postoperatively and compared with the control group. 

Results: Baseline demographic data (age, gender, diagnosis) showed no statistically significant difference between the two groups however the control group performed significantly better in all parameters of gait. All results were analyzed in three ways: time as the main effect, intervention as the main effect, and both time and intervention as the main effect. Data analysis showed that using only time or intervention independently could skew parameters that were statistically significant between the two groups thus using both time and intervention as the main effect proved most accurate. The results demonstrated a significantly greater increase in dorsiflexion in the TAA group, however surprisingly the AF group demonstrated significantly greater plantarflexion. Also counterintuitive, there was no significant change in total ankle sagittal ROM between the two groups. Total coronal ROM was unchanged in the AF group however almost doubled in the TAA group. When time plus intervention were used as the main effect there was no significant difference in CoP progression at any point of the stance phase nor was there a significant difference in vGRF between the two groups. The TAA group however showed a more symmetrical vGRF curve which was closer to that of the control group. 

Conclusions: The options for surgical intervention in ankle arthritis today is, while still very effective, a developing science. The majority of ankle arthritis stems a post-traumatic etiology that in combination with the patients altered biomechanics create a dynamic scenario void of any distinct treatment algorithm. These authors address this challenge citing multiple studies that have conflicting results comparing TAA to AF in respect to various parameters such as pain, ROM, function, and patient satisfaction. This prospective study between the two types of intervention offers valuable information that could have advantages and disadvantages on gait in the future. However, as stated by the authors, the lack of long term follow up and small patient sample size leave much work to be done in the evaluation and comparison of the two treatment modalities.  

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