Summary Kienbock's Disease is the avascular necrosis of the lunate which can lead to progressive wrist pain and abnormal carpal motion. Diagnosis can be made with wrist radiographs in advanced cases but may require MRI for detection of early disease. Treatment is NSAIDs and observation in minimally symptomatic patients. A variety of operative procedures are available depending on severity of disease and patient's symptoms. Epidemiology Incidence most common in males between 20-40 years old Risk factors history of trauma Etiology Pathophysiology thought to be caused by multiple factors biomechanical factors ulnar negative variance leads to increased radial-lunate contact stress decreased radial inclination repetitive trauma anatomic factors geometry of lunate vascular supply to lunate patterns of arterial blood supply have differential incidences of AVN disruption of venous outflow leading to increased intraosseous pressure Blood supply to capitate is also poor and may lead to AVN. Anatomy Blood supply to lunate 3 variations Y-pattern X-pattern I-pattern 31% of patients postulated to be at the highest risk for avascular necrosis Classification Lichtman Classification Stage Description Treatment Stage I No visible changes on xray, changes seen on MRI Immobilization and NSAIDS Stage II Sclerosis of lunate Joint leveling procedure (ulnar negative patients) Radial wedge osteotomy or STT fusion (ulnar neutral patients) Distal radius core decompression Revascularization procedures Stage IIIA Lunate collapse, no scaphoid rotation Same as Stage II above Stage IIIB Lunate collapse, fixed scaphoid rotation Proximal row carpectomy, STT fusion, or SC fusion Stage IV Degenerated adjacent intercarpal joints Wrist fusion, proximal row carpectomy, or limited intercarpal fusion Presentation Symptoms dorsal wrist pain usually activity related more often in dominant hand Physical exam inspection and palpation +/- wrist swelling often tender over radiocarpal joint range of motion decreased flexion/extension arc decreased grip strength Imaging Radiographs recommended views AP, lateral, oblique views of wrist findings (see table above) CT most useful once lunate collapse has already occurred best for showing extent of necrosis trabecular destruction lunate geometry MRI best for diagnosing early disease rule out ulnar impaction findings decreased T1 signal intensity reduced vascularity of lunate Treatment Nonoperative observation, immobilization, NSAIDS indications initial management for Stage I disease outcomes a majority of these patients will undergo further degeneration and require operative management Operative temporary scaphotrapeziotrapezoidal pinning indications adolescent with radiographic evidence of Kienbock's and progressive wrist pain joint leveling procedure indications Stage I, II, IIIA disease with ulnar negative variance initial operative managment technique can be radial shortening osteotomy or ulnar lengthening more evidence on radial shortening radial wedge osteotomy indications Stage I, II, IIIA disease with ulnar positive or neutral variance vascularized bone grafts indications Stage I, II, IIIA, IIIB disease outcomes early results promising, but long-term data lacking best results in Stage III patients distal radius core decompression indications Stage I, II, IIIA disease technique creates a local vascular healing response partial wrist fusions STT capitate shortening osteotomy +/- capitohamate fusion scaphocapitate indications Stage II disease with ulnar neutral or positive variance Stage IIIA or IIIB disease must address internal collapse pattern (DISI) proximal row carpectomy (PRC) indications stage IIIB disease stage IV disease outcomes some studies have shown superior results of STT fusion over PRC for stage IIIB disease wrist fusion indications stage IV disease technique must remove arthritic part of joint total wrist arthroplasty indications Stage IV disease outcomes long-term results not available Techniques Vascularized bone grafts technique many options have been described including transfer of pisiform transfer of distal radius on a vascularized pedicle of pronator quadratus transfers of branches of the first, second, or third dorsal metacarpal arteries 4 + 5 extensor compartment artery (ECA) greatest arc of motion of the most commonly used arterial pedicles temporary pinning of the STT joint, SC joint or external fixation may be used to unload lunate after revascularization Impact of surgical procedure on radiolunate contact stress Impact of surgical procedure on radiolunate contact stress Operative Procedure % decrease on radiolunate contact stress STT fusion 3% Scaphocapitate fusion 12% Capitohamate fusion 0% Ulnar lengthening of 4mm 45% Radial shortening of 4mm 45% Capitate shortening and capitohamate fusion 66%, but 26% increase in radioscaphoid load Prognosis Progressive and potentially debilitating condition if unrecognized and untreated