Summary Scaphoid Fracture Nonunion occur in 5-25% of scaphoid fractures following treatment, and are more common in older patients, smokers, and when there is a delay in the initial treatment of the fracture. Diagnosis is made with a combination of radiographs and a CT scan. MRI studies may be used to assess for avascular necrosis. Treatment is generally open reduction and internal fixation (ORIF) with bone grafting. Epidemiology Incidence 5-10% following immobilization some studies showing nearly 25% following surgical fixation Demographics parallels that of scaphoid fractures 2 :1 male : female most common in third decade of life Risk factors proximal pole fracture vertical oblique fracture pattern displacement >1mm advancing age nicotine use Etiology Pathophysiology pathoantomy lack of stability and/or biology leading to nonunion at fracture site Associated conditions osteonecrosis SNAC (Scaphoid Nonunion Advanced Collapse) Anatomy Osteology complex 3-dimensional structure described as resembling a boat or twisted peanut oriented obliquely from extremity's long axis (implications for advanced imaging techniques) largest bone in proximal carpal row > 75% of scaphoid bone is covered by articular cartilage articulates with radius, lunate, trapezium, trapezoid, and capitate Blood supply major blood supply is dorsal carpal branch (branch of the radial artery) enters scaphoid in a nonarticular ridge on the dorsal surface and supplies proximal 80% of scaphoid via retrograde blood flow minor blood supply from superficial palmar arch (branch of volar radial artery) enters distal tubercle and supplies distal 20% of scaphoid creates vascular watershed and poor fracture healing environment Biomechanics link between proximal and distal carpal row both intrinsic and extrinsic ligaments attach and surround the scaphoid the scaphoid flexes with wrist flexion and radial deviation and extends during wrist extension and ulnar deviation (same as proximal row) See Wrist Ligaments and Biomechanics for more detail Classification Generally divided into stable or unstable nonunion stable maintenance of length and overall alignment with fibrous union unstable loss of length or alignment with signs of carpal instability or degenerative chondral changes Presentation History careful history to detail chronology of injury and treatment may describe remote traumatic event obtain previous operative reports and imaging studies if applicable Symptoms common symptoms some patients will deny any significant symptoms wrist pain login to view 1 more bullet difficulty with grip Physical exam inspection variable degree of swelling tenderness near fracture site note location of previous incision(s) motion document flexion-extension and pronation-supination login to view 1 more bullet Imaging Radiographs recommended views neutral rotation PA and lateral, semi-pronated (45°) oblique view scaphoid view findings cysts, sclerosis, bone resorption at fracture site, hardware loosening or failure carpal instability humpback deformity (distal pole flexes over the volar radioscaphocapitate ligament) SNAC arthritic changes CT indications best modality to evaluate nonunion and for surgical planning suspicion of SNAC arthritic changes views CT should be oriented in plane of scaphoid with 1mm cuts most protocols can reduce metal artifact in post-surgical setting findings provides better detail of fracture pattern orientation, displacement, residual fracture gap, and angulation bony resorption at fracture site may show technical errors from previous surgery evidence of SNAC login to view 1 more bullet MRI indications concern for osteonecrosis sensitivity and specificity inconsistent and questionable utility gadolinium enhancement may improve quality Differential SNAC wrist Diagnosis Clinical and radiographic diagnosis confirmed by history, physical exam, radiographs, and CT MRI needed to assess for AVN Treatment Nonoperative cast immobilization indications login to view 3 more bullets contraindications login to view 1 more bullet outcomes login to view 1 more bullet Operative Open reduction internal fixation with bone grafting indications login to view 3 more bullets technique login to view 1 more bullet outcomes login to view 2 more bullets bone graft options overview login to view 8 more bullets bone morphogenic protein (BMP) and platelet-derived plasma (PRP) login to view 5 more bullets inlay (Russe) non-vascularized corticocancellous bone graft login to view 5 more bullets interposition (Fisk) non-vascularized corticocancellous bone graft login to view 5 more bullets Vascularized local corticocancellous bone graft login to view 7 more bullets Free vascularized corticocancellous bone graft from medial femoral condyle (MFC) login to view 7 more bullets Free vascularized osteochondral graft from medial femoral trochlea (MFT) login to view 7 more bullets Free vascularized corticocancellous bone graft from iliac crest login to view 6 more bullets Techniques Cast immobilization technique long- or short-arm cast pulsed electromagnetic field stimulation may be added serial radiographs to confirm maintenance of fracture alignment and apposition Open reduction internal fixation approach volar or dorsal approach, dictated by previous incision and implant plate is applied through volar approach technique fracture site curetted to bleeding surface cancellous autograft or allograft bone chips may be added to fracture site if desired bone morphogenic protein (BMP) or platelet-derived protein (PRP) may also be added to add osteoinductivity choice of k-wire plate, screw, or staple osteosynthesis headless compression screw placed distal to proximal in the volar approach, or proximal to distal for the dorsal approach plate applied to provide volar buttress k-wire has advantage of removal to avoid symptomatic hardware Bone Grafting techniques Inlay (Russe) bone graft login to view 8 more bullets Interposition (Fisk) bone graft login to view 6 more bullets Vascularized corticocancellous bone graft from dorsal distal radius (Zaidemberg 1,2-ICSRA) login to view 7 more bullets Vascularized radial corticocancellous bone graft using volar carpal artery (Mathoulin) login to view 6 more bullets Vascularized radial corticocancellous bone graft using dorsal capsular pedicle (Sotereanos) login to view 6 more bullets Free vascularized bone graft from medial femoral condyle (MFC) login to view 10 more bullets Free vascularized osteochondral graft from medial femoral trochlea (MFT) login to view 7 more bullets Free vascularized corticocancellous bone graft from iliac crest login to view 7 more bullets Complications Osteonecrosis more common with proximal fracture patterns Graft failure and scaphoid nonunion advanced collapse Prognosis Natural history of disease in some cases derangement of normal carpal mechanics progressive and/or persistent wrist pain cartilage loss scaphoid nonunion with advanced collapse (SNAC)