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 worsened with motion 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 variable degree of motion loss may be attributed to post-immobilization stiffness or mechanical derangement 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 scaphoid, radial styloid, capitate and/or lunate subchondral cyst formation 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 lack of prior appropriate immobilization duration may immobilize up to 6 months following surgery refusal of surgery contraindications technical error with improper screw placement, implant failure, distraction at fracture site with loss of reduction outcomes 69% of surgically stabilized fractures without technical error or fracture displacement achieve union by 3 months with cast and addition of pulsed electromagnetic stimulation Operative Open reduction internal fixation with bone grafting indications lack of fracture union by 6 months technical error with improper implant placement, implant failure, distraction at fracture site with loss of reduction nonunion without osteonecrosis or SNAC technique no clear superiority regarding bone autograft type (vascularized vs. non-vascularized) outcomes 92% union rate likely best outcome when nonunion due to simple technical error during index procedure bone graft options overview bone graft substitutes: PRP, BMP non vascularised graft interposition (Fisk) inlay (Russe) vascularised graft local (pedicled): multiple techniques from distal radius free (requires anastomosis): medial femoral condyle, medial trochlea, iliac crest bone morphogenic protein (BMP) and platelet-derived plasma (PRP) indications nonunion without SNAC used as adjunct to ORIF, avoids technical challenges and resource utilization of free flaps outcomes case series showing high success rate inlay (Russe) non-vascularized corticocancellous bone graft indications no adjacent carpal collapse or excessive flexion deformity (humpback scaphoid) volar approach outcomes 92% union rate interposition (Fisk) non-vascularized corticocancellous bone graft indications adjacent carpal collapse and excessive flexion deformity (humpback scaphoid) volar approach outcomes 72-95% union rates Vascularized local corticocancellous bone graft multiple techniques (Mathoulin, Zaidemberg, Sotrereanos etc) indications waist fractures with proximal pole osteonecrosis lack of intraoperative punctate bleeding at fracture lack of pancarpal arthritis outcomes 82% good to excellent outcomes Free vascularized corticocancellous bone graft from medial femoral condyle (MFC) corticoperiosteal flap that provides highly osteogenic periosteum indications scaphoid waist fracture non-unions with proximal pole osteonecrosis lack of intraoperative punctate bleeding at fracture lack of pancarpal arthritis or collapse outcomes one study showing 100% union achieved by 13 weeks Free vascularized osteochondral graft from medial femoral trochlea (MFT) osteochondral graft indications scaphoid waist fracture non-unions with proximal pole osteonecrosis and loss of cartilage lack of intraoperative punctate bleeding at fracture lack of pancarpal arthritis or collapse outcomes studies reporting over 90% union rate Free vascularized corticocancellous bone graft from iliac crest indications scaphoid waist fracture non-unions with proximal pole osteonecrosis lack of intraoperative punctate bleeding at fracture lack of pancarpal arthritis or collapse outcomes 76% union rate 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 nonvascularized corticocancellous bone graft approach volar approach using interval between the FCR and the radial artery technique various modifications of originally described procedure corticocancellous bone graft harvested from distal radius or iliac crest graft placed within scaphoid acting as cortical strut to restore length, alignment, and angulation headless screw placed across fracture sitebleeding from fracture intra-operatively highly predictive of vascularized proximal pole fragment Interposition (Fisk) bone graft nonvascularized corticocancellous bone graft approach volar approach as above technique corticocancellous distal radius (original technique) or iliac crest (Fernandez modification) bone graft used as anterior wedge to restore length, alignment, and angulation dimensions of graft to be harvested are calculated pre-operatively Vascularized corticocancellous bone graft from dorsal distal radius (Zaidemberg 1,2-ICSRA) approach dorsal approach between 1st and 2nd dorsal extensor compartments artery overlying extensor retinaculum technique 1-2 intercompartmental supraretinacular artery (branch of radial artery) is harvested to provide vascularized graft from dorsal aspect of distal radius longitudinal capsulotomy made overlying scaphoid nonunion bone graft placement depends on nonunion location and deformity correction needed Vascularized radial corticocancellous bone graft using volar carpal artery (Mathoulin) approach volar approach as above artery found distal to the pronator quadratus aponeurosis and radial periosteum technique corticocancellous bone graft and pedicle raised with rim of fascia graft placed as wedge to correct fracture collapse or humpback deformity if present Vascularized radial corticocancellous bone graft using dorsal capsular pedicle (Sotereanos) approach incision centered over the 4th extensor compartment just ulnar to Lister's tubercle technique pedicle uses artery of fourth dorsal compartment located ulnar and distal to Lister's tubercle corticocancellous bone graft harvested with dorsal wrist capsule placed into fracture site in an inlay fashion Free vascularized bone graft from medial femoral condyle (MFC) approach longitudinal incision along posterior border of vastus medialis vastus medialis lifted anteriorly descending genicular vessels identified proximally near adductor hiatus and dissected distally to periosteum overlying condyle identify and protect MCL (distal to flap) technique corticocancellous bone graft harvested from knee using either descending genicular artery, or superomedial genicular vessels if DGA too small utilize the longitudinal branch of the descending genicular artery pedicle (from the superficial femoral artery) bone graft placed volarly as wedge to restore length, alignment, and angulation requires anastomosis Free vascularized osteochondral graft from medial femoral trochlea (MFT) approach same as for free MFC graft technique periosteal branches from DGA identified at condylar flare graft harvested and pedicle raised avascular proximal pole resected and graft placed and fixated with headless screw, plate or K-wire requires anastomosis Free vascularized corticocancellous bone graft from iliac crest approach standard approach for iliac crest bone graft technique identify branch of deep circumflex iliac artery raise corticocancellous graft preserving pedicle place graft into fracture though either volar or dorsal approach requires anastomosis 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)