Syndesmotic Instability After Total Ankle Replacement

Category: Ankle Arthritis Introduction/Purpose: Total ankle replacement (TAR) evolved over the last decades and has been shown to be an effective concept in the treatment of ankle osteoarthritis (OA). In three-component designs, the second interface between polyethylene insert (PI) and tibial component allows the PI to find its position according the individual physiological properties. This was believed to decrease shear forces within the ankle joint. However, it is not clarified to which extent such an additional degree of freedom may overload the ligamentous structures of the ankle joint over time. This may in particular be the case for the syndesmotic ligaments. Therefore, the purpose of this study was to analyze all ankles after TAR that showed a symptomatic overload of the syndesmotic ligaments and to determine the potential consequences. Methods: Between 2003 and 2017, 31 ankles (females, 17; males 14; mean age 60 [40-79] years) were treated with a tibio-fibular fusion for a symptomatic instability of the syndesmosis. The indication for TAR was posttraumatic OA in 27 (87%), primary OA in 3 (10%), and hemochromatosis in one ankle (3%). The 31 ankles included 23 primary TAR (74%), 6 revision TAR (19%), and two take-down of a fusion and conversion to TAR (7%). Criteria for fusion were the presence of at least two of the followings: (1) tenderness over the syndesmosis, (2) pain while compressing the fibula against the tibia (squeeze test), (3) pain while rotating the foot externally (external rotation test), (4) widening of the syndesmosis on an anteroposterior view. Alignment of TAR (tibial articular surface [TAS] angle) and hindfoot alignment were measured on standard radiographs. Intraoperatively, the syndesmotic instability was confirmed before fusion. The wear of PI was documented. Results: After a mean of 63 (range, 4 – 152) months after TAR, all patients evidenced pain at the level of the syndesmosis of at least 3 months. 25 ankles (81%; 24 after posttraumatic OA) showed a widening of the syndesmotic space and 22 ankles (71%) of the medial clear space with lateral translation of the talus. The PI was seen to overlap the tibial component in 15 ankles (48%). Nine ankles (29%) evidenced cyst formation, and eight ankles (26%) showed a decrease in height of the PI; whereas, in 3 ankles (10%) a fracture of the PI was found. A valgus misalignment of the heel was found in 25 ankles (81%), a valgus TAS in 16 (52%) and a varus TAS in 11 ankles (36%). Conclusion: A syndesmotic instability after a three-component TAR apparently occurred mostly after posttraumatic OA, in particular if the heel was left in valgus. If the talus starts to move lateralward, the PI seems to be at risk for increased wear and finally mechanical failure (Figure 1). Therefore, a valgus misaligned heel should always be corrected during TAR implantation. If there is any sign of syndesmotic instability, a fusion should be considered. Further studies must proof whether in cases with a syndesmotic instability the use of a two-component design will be superior, as it stabilizes the talus in the coronal plane

Novel Double Osteotomy Technique of Distal Tibia for Correction of Asymmetric Varus Osteoarthritic Ankle

Category: Ankle, Ankle Arthritis Introduction/Purpose: A most challenging condition for balancing a varus arthritic ankle is the presence of a defect in the medial tibial plafond. After our initial results with a medial tibial plafond plasty did not fulfill our expectations of success, we hypothesized that adding a correcting supramalleolar osteotomy of the distal tibia would move the loading force to the tibiotalar joint more medially and thus act as an evertor force to the talus. In this study we asked (1) what surgical technique was used in detail; (2) what complications were observed; (3) what is the postoperative pain relief; (4) what is the patients’ mid-term functional outcome including range of motion; (5) what is the patients’ mid-term radiographic outcome including hindfoot alignment and progression of ankle osteoarthritis? Methods: Twenty consecutive patients were included into this study, no patients were lost for follow-up with a 4-year minimum required by the study. The mean age of the patients was 44 ± 12 years (range, 17-60 years). Followup averaged 5.9 ± 2.1 years (range, 4-11.2 years). All intraoperative and postoperative complications were recorded. The postoperative pain relief was assessed using a visual analog scale (VAS). Functional outcomes were assessed using the American Orthopaedic Foot and Ankle Society (AOFAS) hindfoot score and by measuring the ankle’s range of motion. Weight-bearing radiographs were used to assess osteotomy union and hindfoot alignment. Hindfoot alignment was assessed by measurement of the tibial ankle surface (TAS) angle, the tibiotalar (TT) angle, tibial lateral surface (TLS) angle, the tibiotalar tilt, and the moment arm of the calcaneus. Osteoarthritis grading was performed preoperative and postoperatively according to Takakura et al. Results: There were no intraoperative or perioperative complications. All patients had osseous fusion within 6 postoperative months. The average VAS pain score decreased significantly from 7.9 ± 1.3 (range, 6-10) to 1.3 ± 1.6 (range, 0-7). The average AOFAS hindfoot score increased significantly from 49 ± 15 points (range, 36-68) preoperatively to 86 ± 12 points (range, 66-96) postoperatively. The mean preoperative and postoperative ankle range of motion were comparable with 39° ± 11° (range, 25°- 46°) and 38° ± 9° (range, 28°-46°). The varus tilt improved significantly from 19.4° ± 8.2° (range, 6°-32°) to 6.9° ± 3.9° (range, 1°- 12°). According to Takakura’s classification, three ankles deteriorated by one stage, 11 ankles improved by one stage, and six ankles showed no changes. Conclusion: The novel double osteotomy was found to be an efficient and successful method to restore tibiotalar joint congruency and to normalize hindfoot alignment. The key of success of medial tibial plafond plasty may be the move of the joint load medially by the additional supramalleolar correcting osteotomy, thus creating an eversion force to the talus. Further in vitro studies are needed to evaluate these hypotheses