In vivokinematics of three-component mobile-bearing total ankle replacement in rheumatoid ankle with talocalcaneal arthrodesis and spontaneous talocalcaneal fusion

Comparison of clinical and radiographic results of mobile-bearing total ankle arthroplasty between osteoarthritis and rheumatoid arthritis

OBJECTIVES

Clinical results of mobile-bearing total ankle arthroplasty (TAA) for rheumatoid arthritis (RA) have been reported, but no studies have compared osteoarthritis (OA) and RA. Clinical and radiographic outcomes after at least 3 years were compared between OA and RA.

METHODS

Eleven ankles with OA and 22 ankles with RA were followed after mobile-bearing TAA (FINE total ankle system). Clinical outcomes were assessed by the American Orthopaedic Foot and Ankle Society (AOFAS) score. Radiographic outcomes were evaluated by the angular position of the implant, radiolucent lines, migration, and subsidence. Operative and postoperative complications were assessed.

RESULTS

There were no significant differences in clinical outcomes, radiographic outcomes, or complications, except the final follow-up AOFAS total score (OA: 89.4 vs RA: 78.2; p = .044) and pain score (OA: 37.3 vs RA: 30.5; p = .041) at a mean follow-up of 83.4 months. Delayed wound healing occurred in 9.1% in RA and none in OA. Radiolucent lines were observed in 45% of both groups, and implant removal was performed in 9.1% and 18.2% of OA and RA, respectively; there were no significant differences.

CONCLUSIONS

The final follow-up AOFAS total score and pain score were significantly higher in OA after the FINE total ankle system. There was a discrepancy between radiographic abnormalities and implant removal in both OA and RA.

Effects of lateral instability on ankle coupled motions in vivo using 3D fluoroscopy

Lateral ankle instability (LAI) compromises the normal kinematics of the ankle, affecting activities of daily living. In vitro kinematics of ankles with LAI during single-plane motions are available, but the active control stability of these motions remains unclear. The current study measured the 3D ankle kinematics during unresisted single-plane motion tests using a bi-plane fluoroscope with a CT model-based 2D/3D registration method in 12 patients with LAI and 14 healthy peers. The coupling of the kinematic components at the talocrural and subtalar joints was quantified by the path difference between the forward and return paths of the coupled motion. Significantly increased path differences were found in the subtalar dorsiflexion/plantarflexion and inversion/eversion components during internal/external rotation tests (p < 0.05). During inversion/eversion, significantly reduced tibiocalcaneal ranges of motion and the path differences in the talocrural and subtalar dorsiflexion/plantarflexion components were noted (p < 0.05). The current results suggest that chronic LAI had compromised control stability at the subtalar joint during internal/external rotation tests and a conservative motion control strategy with significantly reduced ranges of motion to maintain good control of out-of-plane motion components in response to direct challenges of the anterior talofibular ligament during inversion/eversion tests. The current results also suggest that, compared to kinematic patterns of individual components, the path difference of the coupled motion may serve as a better measure of the motion control stability of the ankle in differentiating LAI from healthy controls.

Assignment of local coordinate systems and methods to calculate tibiotalar and subtalar kinematics: A systematic review

The introduction of biplane fluoroscopy has created the ability to evaluate in vivo motion, enabling six degree-of-freedom measurement of the tibiotalar and subtalar joints. Although the International Society of Biomechanics defines a standard method of assigning local coordinate systems for the ankle joint complex, standards for the tibiotalar and subtalar joints are lacking. The objective of this systematic review was to summarize and appraise the existing literature that (1) defined coordinate systems for the tibia, talus, and/or calcaneus or (2) assigned kinematic definitions for the tibiotalar and/or subtalar joints. A systematic literature search was developed with search results limited to English Language from 2006 through 2020. Articles were screened by two independent reviewers based on title and abstract. Methodological quality was evaluated using a modified assessment tool. Following screening, 52 articles were identified as having met inclusion criteria. Methodological assessment of these articles varied in quality from 61 to 97. Included articles adopted primary methods for defining coordinate systems that included: (1) anatomical coordinate system (ACS) based on individual bone landmarks and/or geometric shapes, (2) orthogonal principal axes, and (3) interactive closest point (ICP) registration. Common methods for calculating kinematics included: (1) joint coordinate system (JCS) to calculate rotation and translation, (2) Cardan/Euler sequences, and (3) inclination and deviation angles for helical angles. The methods each have strengths and weaknesses. This summarized knowledge should provide the basis for the foot and ankle biomechanics community to create an accepted standard for calculating and reporting tibiotalar and subtalar kinematics.

Radiographic Outcomes of Mobile-Bearing Total Ankle Arthroplasty for Patients With Rheumatoid Arthritis

BACKGROUND

Ankle disorders in patients with rheumatoid arthritis (RA) reduce their quality of life and activities of daily living. The aim of this study was to evaluate the midterm clinical and radiographic outcomes of TAA in patients with RA.

METHODS

This retrospective study included patients with a minimum follow-up of 2 years. A total of 37 RA patients (39 ankles) were enrolled in this study from August 2006 to March 2016. All the patients had undergone primary cemented mobile-bearing total ankle arthroplasty (TAA). Nine ankles received arthrodesis of the subtalar joint simultaneously. Patient-reported outcomes were measured preoperatively and at the latest follow-up by Self-Administered Foot-Evaluation Questionnaire (SAFE-Q). Radiographs of the ankle were analyzed preoperatively and at all follow-up visits to measure the periprosthetic radiolucent line, migration of the tibial component, and the subsidence of the talar component. Intraoperative and postoperative complications were recorded. The average duration of follow-up for the entire cohort was 5.0 ± 2.0 years (range 2.1-10.1 years).

RESULTS

All subscales of the SAFE-Q had improved significantly at the latest follow-up. No significant difference was found between the range of motion of the ankle before and after the surgery. Radiolucent lines were observed in 28 (73.7%) ankles. Migration of the tibial component and subsidence of the talar component were found in 8 (21.1%) and 11 (28.9%) ankles, respectively. Intraoperative malleolus fractures occurred in 3 (7.7%) ankles and delayed wound healing in 10 (25.6%) ankles. Four ankles were removed because of deep infection or noninfective loosening, resulting in an implant survival rate of 88.4% (95% CI, 0.76-1.0) at 10 years.

CONCLUSION

The midterm patient-reported outcomes and implant retention rate after cemented mobile-bearing TAA for RA patients were satisfactory. However, a low radiographic implant success rate was observed.

LEVEL OF EVIDENCE

Level IV, retrospective case series.