Summary Scaphoid Nonunion Advanced Collapse (SNAC) describes the specific pattern of progressive arthritis of the wrist that results from a chronic scaphoid nonunion. Diagnosis is made clinically with progressive wrist pain and wrist instability with radiographs showing scaphoid fracture nonunion with advanced arthritis of the radioscaphoid joint. Treatment involves observation in early stages of disease. A variety of operative procedures may be indicated depending on severity of disease and patient's symptoms. Etiology Pathophysiology pathoanatomy natural history of degenerative changes first occurs at the radioscaphoid area followed by pancarpal / midcarpal arthritis Anatomy Scaphoid anatomy 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 motion both intrinsic and extrinsic ligaments attach and surround the scaphoid the scaphoid flexes with wrist flexion and radial deviation and it extends during wrist extension and ulnar deviation (same as proximal row) also see Wrist Ligaments and Biomechanics for more detail Classification Radiographic Classification Stage I Arthrosis localized to the radial side of the scaphoid and radial styloid Stage II Scaphocapitate arthrosis in addition to Stage 1 Stage III Periscaphoid arthrosis (proximal lunate and capitate may be maintained) Presentation Symptoms weakness reduced grip and pinch strength stiffness stiffness with extension and radial deviation Physical exam palpation localized tenderness of the radioscaphoid articulation motion decreased wrist motion on extension and radial deviation Imaging Radiographs recommended view ap and lateral of wrist findings see radiographic classification above Differential SLAC wrist Scaphoid fracture nonunion Treatment Nonoperative observation alone indications medically frail and low functioning patients only Operative radial styloidectomy plus scapholunate reduction and stabilization indications stage I proximal row carpectomy indications stage II and III outcomes disadvantages reduction of wrist motion and grip strength procedure should be avoided if there are capitate head degenerative changes four-corner fusion indications stage II and III outcomes retains 60% of wrist motion and 80% of grip strength wrist arthrodesis indications stage II and III Prognosis Patients with scaphoid nonunions of > 5 years duration or proximal pole necrosis have less favorable outcomes Punctate bleeding of bone during surgery is a good prognostic indicator of union 92% union with obvious bleeding, 71% with questionable bleeding, 0% with no bleeding results show decreased rate of arthritis (down to 40-50%)
Technique Guide Technique guides are not considered high yield topics for orthopaedic standardized exams including ABOS, EBOT and RC. Four Corner Wrist Fusion Orthobullets Team Hand - Scaphoid Lunate Advanced Collapse (SLAC)
QUESTIONS 1 of 3 1 2 3 Previous Next (SBQ17SE.11) A 67-year-old woman presents with chronic insidiously progressive right wrist pain. Her history is only significant for a remote fall onto her wrist 25 years prior. A radiograph of her affected wrist is shown in Figure A. After extensive discussion, she elects to undergo a salvage motion-sparing procedure that relies on the intact cartilage of the capitate head. During the dissection, the most volar-radial ligament is excised. What is her anticipated outcome? QID: 211226 FIGURES: A Type & Select Correct Answer 1 Improved pain and increased range of motion by 3 months 15% (255/1686) 2 Ulnar translocation of the carpus 69% (1166/1686) 3 Capitate avascular necrosis 3% (45/1686) 4 Distal radio-ulnar joint instability 5% (77/1686) 5 Progression of radio-styloid arthritis 8% (130/1686) L 3 Question Complexity A Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 2 Review Tested Concept Review Full Topic Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK (OBQ07.78) A 30-year-old female reports 5 months of wrist pain after a fall onto her wrist. A radiograph is shown in Figure A. If untreated, which of the following is least likely to occur during the natural progression of the disease process? QID: 739 FIGURES: A Type & Select Correct Answer 1 Radial styloid osteophyte 6% (266/4242) 2 Radioscaphoid arthritis 10% (441/4242) 3 Midcarpal arthritis 11% (478/4242) 4 Scaphocapitate arthritis 14% (597/4242) 5 Radiolunate arthritis 57% (2430/4242) L 3 Question Complexity D Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 5 Review Tested Concept Review Full Topic
All Videos (1) Podcasts (0) Login to View Community Videos Login to View Community Videos Four corner arthrodesis for SNAC wrist Derek W. Moore Hand - Scaphoid Nonunion Advanced Collapse (SNAC) A 11/2/2014 1493 views 4.6 (8)
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