A Novel Approach to Treat a Rare Case of Interprosthetic Humeral Fracture with Osteosynthesis and Combined Grafting: A Case Report and Review of the Literature.

Interprosthetic humeral fractures (IHFs) are severe injury patterns associated with surgical issues and contradictory results. The knowledge and literature on this topic are still lacking. A 76 year-old woman was treated for a fracture occurred between the shoulder and elbow stemmed prosthesis. Severe bone loss was associated with the fracture. Treatment: Open reduction, plate fixation, and bone grafting were considered. A xenograft (used as a mechanical strut medially), a synthetic graft associated with bone growth factors, and scaffolds improved the bone healing process. Satisfactory clinical and radiological outcomes were obtained. A scoping review of the literature was also performed by the authors. Only eight papers reported IHFs with a low level of evidence. In total, eight patients were treated; one paper that reported on biomechanical aspects using finite element analysis is discussed. Conservative treatment leads to non-union, and the surgical approach is the gold standard. The osteosynthesis technique associated with bone grafting leads to the best outcomes. The use of a xenograft mechanical strut, associated with synthetic biological bone grafting, led to complete bone union at 9 months follow-up. Larger cohorts, more standardised results, and multicentric studies are mandatory in order to improve and establish a management and treatment algorithm.