Distal Tibial Oblique Osteotomy Combined with Strut Bone Allografting for the Treatment of Ankle Osteoarthritis with Varus Deformity: A Case Series

Background: Advanced varus ankle osteoarthritis is challenging because correction of malalignment must be balanced against preservation of the native ankle joint. This study evaluated the clinical and radiographic outcomes of distal tibial oblique osteotomy (DTOO) with structural strut allografting, which permits individualized correction and provides mechanical support to the osteotomy gap. Methods: This retrospective case series included 20 patients and 20 operated ankles with Takakura stage IIIa (n = 13) or IIIb (n = 7) varus ankle osteoarthritis who underwent DTOO with structural strut allografting between 2012 and 2024. Clinical outcomes included Manchester–Oxford Foot Questionnaire (MOXFQ), American Orthopaedic Foot & Ankle Society (AOFAS), 12-Item Short-Form Survey (SF-12), and Visual Analog Scale (VAS) pain scores. Radiographic parameters included tibial articular surface angle (TAS), tibial lateral surface angle (TLS), medial malleolar angle (MMA), talar tilt angle (TTA), and tibiotalar surface angle (TTS). Results: Significant improvements were observed at final follow-up. MOXFQ scores decreased from 57.66 ± 22.01 to 10.63 ± 9.72 (p < 0.001), AOFAS scores increased from 63.75 ± 15.17 to 85.45 ± 8.37 (p < 0.001), and VAS pain scores decreased from 4.30 ± 1.75 to 1.00 ± 1.30 (p < 0.001). The SF-12 PCS increased from 45.23 ± 8.48 to 47.96 ± 7.93 (p = 0.258), and the MCS increased from 53.51 ± 9.85 to 55.60 ± 4.75 (p = 0.377); neither change was statistically significant. Significant correction was achieved in TAS (p < 0.001), TLS (p < 0.001), MMA (p = 0.019), and TTS (p < 0.001), with no significant change in TTA (p = 0.336). All achieved radiographic union within 3 months postoperatively. Conclusions: DTOO with strut bone allografting enables alignment correction in advanced varus ankle osteoarthritis, including Takakura stage III, while preserving the ankle joint. This technique is an effective joint-preserving option for severe deformities.