Suguru Yokoo1,2, Kenta Saiga3, Koji Demiya1,4, Hideki Ohashi1,5, Masahiro Horita1,6, Toshifumi Ozaki1. 1. Department of Orthopaedic Surgery, Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, 2-5-1 Shikata-cho, Okayama, 700-8558, Japan. 2. Department of Orthopaedic Surgery, National Hospital Organization Okayama Medical Center, 1711-1 Tamasu, Kita-ku, Okayama, 701-1192, Japan. 3. Department of Sports Medicine, Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, 2-5-1 Shikata-cho, Kita-ku, Okayama, 700-8558, Japan. kentasaiga@okayama-u.ac.jp. 4. Department of Orthopaedic Surgery, Tsuyama Chuo Hospital, 1756 Kawasaki, Tsuyama, 708-0841, Japan. 5. Department of Orthopaedic Surgery, Takahashi Central Hospital, 53 Minami-cho, Takahashi, 716-0033, Japan. 6. Department of Orthopaedic Surgery, Okayama City General Medical Center Okayama City Hospital, 3-20-1 Kitanagaseomote-cho, Kita-ku, Okayama, 700-8557, Japan.
Abstract
BACKGROUND: Arthroscopic ankle arthrodesis (AAA) has risks of complications, such as delayed union and non-union. The number and direction of the inserted screws have been reported as important factors affecting the time to union of AAA. However, the ratio of inter-screw distance (ISD) to tibial width (TW) in different planes has not been investigated. Therefore, we aimed to explore the effect of this ratio on bone union following AAA. METHODS: We retrospectively enrolled 63 patients (64 ankles) undergoing AAA from 2013 to 2019. Then, their age, body mass index (BMI), sex, diabetes mellitus (DM) status, Takakura-Tanaka classification, number of screws and radiographic parameters were analysed. RESULTS: The patients had a mean age of 70.3 (range, 45-91) years. Bone fusion was achieved in 57 ankles (89%) in a mean period of 3.3 (range, 2-6) postoperative months. There were four cases of delayed union and three of non-union. No significant differences in age, BMI, sex, DM, Takakura-Tanaka classification, and number of screws could be detected between the groups. However, the sagittal ISD/TW ratio was significantly larger in the union group than in the delayed/non-union group with a cut-off value of 57.0%. CONCLUSION: Larger sagittal ISD/TW ratios result in reduced post-AAA delayed union or non-union. The surgeon should be aware that the anterior and posterior screw widths should be approximately 60% or more of the anteroposterior width of the tibia.
BACKGROUND: Arthroscopic ankle arthrodesis (AAA) has risks of complications, such as delayed union and non-union. The number and direction of the inserted screws have been reported as important factors affecting the time to union of AAA. However, the ratio of inter-screw distance (ISD) to tibial width (TW) in different planes has not been investigated. Therefore, we aimed to explore the effect of this ratio on bone union following AAA. METHODS: We retrospectively enrolled 63 patients (64 ankles) undergoing AAA from 2013 to 2019. Then, their age, body mass index (BMI), sex, diabetes mellitus (DM) status, Takakura-Tanaka classification, number of screws and radiographic parameters were analysed. RESULTS: The patients had a mean age of 70.3 (range, 45-91) years. Bone fusion was achieved in 57 ankles (89%) in a mean period of 3.3 (range, 2-6) postoperative months. There were four cases of delayed union and three of non-union. No significant differences in age, BMI, sex, DM, Takakura-Tanaka classification, and number of screws could be detected between the groups. However, the sagittal ISD/TW ratio was significantly larger in the union group than in the delayed/non-union group with a cut-off value of 57.0%. CONCLUSION: Larger sagittal ISD/TW ratios result in reduced post-AAA delayed union or non-union. The surgeon should be aware that the anterior and posterior screw widths should be approximately 60% or more of the anteroposterior width of the tibia.