Bone substitute fracture in open wedge high tibial osteotomy: Comparison of two different bone substitutes

Purpose The aim of this study was to retrospectively compare bone substitute fracture patterns and outcomes in patients who underwent open wedge high tibial osteotomy (OWHTO) with OSferion60 or OSferion60 Marvelous bone substitutes. Patients with and without bone substitute fractures were compared and risk factors for bone substitute fracture were identified. Methods Included patients were physically active non-smokers with knee osteoarthritis and deformity in the proximal tibia, persistent pain, and <5° of flexion contracture. OWHTO was performed with a TriS plate and a target femorotibial angle (FTA) of 170°. Full weight-bearing began the day after surgery. Pre-, intra-, and post-operative evaluations of demographic, clinical, and radiological factors were performed. Regression analysis was performed to identify risk factors for bone substitute fracture. Results Data for 63 patients were analyzed (OSferion60, n ​= ​28 and Marvelous, n ​= ​35; bone substitute fracture, n ​= ​32 and non-bone substitute fracture, n ​= ​31). No significant differences were found between the bone substitute groups in patient characteristics and pre-operative and 2-year FTA, Japanese Orthopaedic Association (JOA) score, and flexion range. FTA and JOA scores improved significantly 2 years post-operatively (both p ​< ​0.001). There were 32 bone substitute fractures (OSferion60, n ​= ​20; Marvelous, n ​= ​12); all occurred by the 1-month follow-up. Gap filling occurred significantly earlier in the Marvelous group versus the OSferion60 group (p ​< ​0.001). Risk factors for bone substitute fracture were weaker bone substitute [odds ratio (OR) ​= ​8.34; p ​< ​0.001] and lateral hinge fracture (OR ​= ​11.7; p ​= ​0.045). Conclusions Although bone substitute fracture was common in both bone substitute groups, this did not affect outcomes. However, lateral hinge fractures are a particular concern.