summary Humeral Shaft Nonunion is characterized by the arrest of the fracture repair process of a humeral shaft fracture which may occur following nonoperative or operative management. Diagnosis can be made with plain radiographs. CT studies are helpful to assess the extent of bridging callous and for preoperative planning. Treatment is generally open reduction with compression plating with or without bone grafting. Epidemiology Incidence of primary nonunion 2 to 33% with nonoperative management 5 to 10% with surgical management Anatomic location proximal third humeral shaft fractures are felt to have higher rates of nonunion Risk factors biologic metabolic/endocrine abnormalities (osteoporosis, Vitamin D deficiency most common) infection patient factors (smoking, obesity, malnutrition, noncompliance) open fracture mechanical unstable fracture patterns with inadequate stability shoulder or elbow stiffness (motion directed to fracture site) Etiology Pathophysiology pathophysiology inadequate stability at fracture site with operative or nonoperative treatment pathobiology inadequate biology as a result of metabolic/endocrine abnormalities, infection, smaller bone surface area for healing Associated conditions radial nerve palsy Anatomy Blood Supply nutrient vessel of humerus courses along the medial aspect of the mid to distal third of the diaphysis Muscles pectoralis major and deltoid create strong deforming forces on proximal diaphyseal fractures Tendon biceps tendon interposition in proximal diaphyseal fractures may lead nonunion Presentation Symptoms pain with use of the extremity Physical exam inspection assess the fit of functional brace and skin irritation atrophy angulation motion gross motion at the fracture site neurovascular assess radial nerve function Imaging Radiographs recommended views AP and lateral of the humerus, shoulder, and elbow findings lack of fracture consolidation hypertrophic callous formation pseudarthrosis CT indications to evaluate for the extent of bridging callous and preoperative planning Studies Serum Labs CRP, ESR, CBC must rule out infection total protein and serum albumin vitamin D, TSH, PTH Treatment Nonoperative functional bracing +/- bone stimulation indications rarely indicated unless low demand, high-risk surgical candidate, and asymptomatic nonunion modalities continued functional brace bone stimulators nonunion over a period greater than 9 months or no progressive healing 3 months from injury contraindicated if pseudarthrosis, fracture gap >5mm, or poor blood supply Operative compression plating with bone grafting (gold standard) indications symptomatic nonunion outcomes shown to be superior to IM nailing dual plating indications very proximal or distal fracture nonunion poor metaphyseal bone quality micromotion noted at fracture site following single plate fixation outcomes 92-100% union at 16 weeks cortical strut allograft/autograft indications severe osteopenia from disuse, age, or prior surgery severe bone loss recalcitrant nonunion outcomes 95-100% union rate bone morphogenic proteins (BMP's) indications limited role as no studies show improved outcomes Techniques Compression plating with or without bone grafting approach anterior anterolateral posterior radial nerve exploration and neurolysis or release of nerve entrapment soft tissue radial nerve protection and neurolysis bone work debridement of fibrous tissue and bone ends to stimulate healing fracture reduction with maximal cortical contact and stability autologous bone grafting from ICBG if atrophic nonunion DBM, RIA, or local callous autograft as alternative grafts instrumentation 4.5mm compression plate placed anterior, lateral, or posterior complications specific to this treatment radial nerve neuropraxia or injury ICBG donor site morbidity outcomes nearly 100% union rate reported 44% rate of ICBG donor site morbidity Dual plating instrumentation place additional plate orthogonal to the first plate Cortical strut allograft/autograft bone work place strut intramedullary and then place the plate place strut medially and place laterally based compression plate Complications Nerve injury radial nerve most common Persistent nonunion treatment free fibular grafting indications recalcitrant atrophic nonunions Prognosis With operative treatment of nonunion, 83-100% of patients go on to union