Gap healing after medial open-wedge high tibial osteotomy using injectable beta-tricalcium phosphate

Purpose: The study aim was to evaluate gap healing after medial open-wedge high tibial osteotomy (MOWHTO) using novel injectable beta-tricalcium phosphate (β-TCP) as gap filler. We also aimed to evaluate radiographic and clinical outcome of MOWHTO using injectable β-TCP. Methods: Consecutive 28 patients underwent MOWHTO using anatomical locking plate fixation, and β-TCP was injected as gap filler. Serial radiographs and computed tomography were taken at postoperative 3 and 12 months, and gap healing was assessed. Lower extremity alignment was measured on radiographs, and clinical outcome was evaluated by determining International Knee Documentation Committee, Western Ontario and McMaster Universities Arthritis Index, and visual analogue scales for pain scores. Results: Progress of bone union was found on plain radiographs, and the mean ratio (β-TCP/host bone) of computed tomography attenuation values significantly changed from postoperative 3 months to 12 months, which indicates maturation of β-TCP. The average mechanical femoro-tibial angle changed from 4.1° varus (preoperative) to 4.8° valgus (3 months) and maintained until 12 months (4.3° valgus). All clinical outcome scores were significantly improved and no significant complication occurred. Conclusion: Using injectable β-TCP as gap filler for MOWHTO resulted in satisfactory gap healing without complication. Radiographic and clinical results were satisfactory. The injectable β-TCP can be a safe and effective option for gap filling after MOWHTO.