SLAC y SNAC de la muñeca

This is the clinical evidence summary written for health professionals. It is technical, and it lists the research this page was built from. You do not need to read it to understand your treatment or to make a decision about it.

Overview¶

Pathophysiology and Anatomy¶

• Scapholunate interosseous ligament injury and extrinsic ligament complex attenuation lead to palmar flexion of the scaphoid and extension of the lunate, resulting in dorsal intercalated segment instability [12].
• The radioscaphoid joint becomes incongruous following scaphoid flexion, leading to altered normal radioscaphoid contact forces and the development of arthrosis [12].
• As the scaphoid flexes and the scapholunate diastasis increases, the capitate migrates proximally [12].
• Altered intercarpal contact forces result in arthrosis at the capitolunate joint [12].
• The styloscaphoid, radioscaphoid, and capitolunate joints are affected by SLAC wrist arthritic changes [12].
• The radiolunate joint is typically spared in SLAC wrist due to its spheroid shape [12].
• In SNAC wrist, the distal scaphoid articular surface with the radial styloid is affected first in stage I [12].
• The proximal scaphoid pole and radioscaphoid fossa may be preserved in stage I SNAC wrist [12].
• Bone density was greater at the capitolunate joint, the radial styloid, and the radiolunate joint in SNAC wrists compared to controls [7].

Clinical Presentation¶

• SLAC wrist presents with reduced grip and pinch strength [12].
• SLAC wrist presents with stiffness with extension and radial deviation [12].
• SLAC wrist presents with localized tenderness at the radioscaphoid articulation [12].
• SLAC wrist presents with decreased wrist motion on extension and radial deviation [12].
• A positive Watson shift test in SLAC wrist occurs when pressure directed over the palmar scaphoid tuberosity while moving the wrist from ulnar to radial deviation causes the scaphoid to subluxate dorsally out of the scaphoid fossa and relocate when pressure is released [12].

Treatment Indications and Principles¶

• Partial wrist fusion is indicated for painful posttraumatic and osteoarthritic conditions of the wrist that affect only part of the articulating system in a patient keen to have adequate pain control while preserving useful motion [10].
• Common indications for partial wrist fusion include SLAC wrist, SNAC wrist, Kienböck disease, STT arthritis, and posttraumatic radiocarpal arthritis [10].
• Chronic painful dissociative or nondissociative carpal instabilities with or without secondary arthritic change are good indications for partial wrist fusion [10].
• In inflammatory arthritis, the disease should be in a quiescent stage to avoid ongoing clinical deterioration due to disease progression before partial wrist fusion [10].
• Partial wrist fusion is contraindicated when there is active sepsis, panarthritis, and rapidly progressive joint destruction at a proliferative stage [10].
• Partial wrist fusion is not a guarantee of pain relief [10].
• The potential advantage of partial wrist fusion in preservation of a useful arc of motion may be offset by the risks of nonunion or by continued pain despite successful fusion [10].
• Chronic smokers have a higher incidence of nonunion, so alternatives for pain control such as a wrist denervation can be considered [10].
• Arthroscopic partial wrist fusions are technically demanding procedures and require extensive arthroscopic experience [10].
• Patients with preexisting extensor tendon pathology over the wrist region may have a higher incidence of tendon complications associated with arthroscopic partial wrist fusion [10].
• Arthrofibrosis and long-standing carpal collapse may pose additional difficulty and risk for arthroscopic partial wrist fusion [10].
• Partial wrist fusion is a motion-preserving salvage procedure that allows fusion of painful segments while preserving motion in unaffected segments [18].
• Partial wrist fusion helps to halt predictable mechanical collapse of the carpal central column and maintain carpal height in conditions caused by dissociative lesions or loss of bony integrity such as SNAC wrist [18].
• Arthroscopic partial wrist fusion has the potential advantages of minimal surgical damage to supporting ligaments and capsular structures while allowing an unimpeded view of the joint [18].
• Arthroscopic assessment ensures a more accurate staging of the arthritis and facilitates clinical decision making on the most appropriate choice of fusion [18].
• Arthroscopic treatment is particularly attractive for a patient conscious of esthetic outcome [10].

Specific Procedures¶

• Scaphoid excision and four-corner fusion is indicated for the treatment of the SLAC/SNAC wrist when significant pain is refractory to nonoperative measures [6].
• Midcarpal arthrodesis is a reliable procedure for treating SLAC- and SNAC-wrists in stages II and III which preserves some range of motion [1].
• Both proximal row carpectomy and four-corner fusion provide improvements in pain and subjective outcome measures for patients with symptomatic and appropriately staged SLAC or SNAC wrists [2].
• Findings favor Limited Carpal Fusion compared to Proximal Row Carpectomy for SNAC and SLAC wrist conditions, except for flexion-extension and grip strength in women [3].
• The authors prefer proximal row carpectomy for SLAC wrists with preserved capitate head cartilage due to socio-economic benefits, lower complication rates, and procedural ease [29].
• Arthroscopic wrist debridement and radial styloidectomy is indicated for SLAC II or SLAC III wrists as an intermediate step to relieve pain and preserve functional motion [21].
• Arthroscopic wrist debridement and radial styloidectomy may have advantages in relieving pain while preserving wrist motion for SLAC stage 2 or 3 disease [33].
• Arthroscopic resection arthroplasty of the radial column (ARARC) may be a viable surgical option for patients with SLAC wrist who desire a minimally invasive procedure [58].
• Scaphoidectomy and capsulodesis is mostly indicated as a palliative procedure in elderly patients with posttraumatic SNAC or SLAC wrist with limited functional demands [14].
• Successful scaphoid reconstruction in SNAC wrists shifts the load back onto the proximal pole and interrupts the otherwise inevitable degenerative pattern in scaphoid nonunions [13].
• Radial styloidectomy is suitable for stage I SLAC and SNAC wrist conditions [11].
• Performing radial styloidectomy arthroscopically has the advantage of better visualization and can limit the potential injury of the RSC ligament [11].
• Nakamura et al. recommended styloidectomy of no more than 3-4 mm as increased radial translation with ulnar and palmar carpal displacement had been demonstrated after 6-mm and 10-mm radial styloidectomy [11].
• The dorsal rim of the radial styloid is a common site of occurrence of early SNAC and SLAC wrist changes and should be assessed in all cases at arthroscopic surveillance [11].
• The origins of the RSC and LRL ligament on the distal radius mark the ulnar extent of the resection during arthroscopic radial styloidectomy [11].
• The volar aspect of the radial styloid can be spared during arthroscopic radial styloidectomy as it is the important origin of the RSC ligament and impingement symptom seldom arises from this area [11].
• Total or subtotal scaphoidectomy is a useful clinical technique as a concomitant procedure for midcarpal arthrodesis in SLAC wrist and SNAC wrist [11].

Anatomy & Pathophysiology¶

Bony Anatomy¶

• The carpus comprises eight ossicles traditionally separated into a proximal row (scaphoid, lunate, triquetrum, pisiform) and a distal row (trapezium, trapezoid, capitate, hamate) [37].
• The distal radius articular surface features two concave facets for the scaphoid and lunate, separated by the scapholunate ridge [37].
• The capitate head often relies on a retrograde vascular supply [37].
• The scaphoid's primary vascular supply is a branch of the radial artery at the dorsal ridge, with smaller vessels entering the palmar tubercle to supply the distal 30% [37].
• The lunate is broader palmarly than dorsally [37].
• The pisiform is a sesamoid bone within the flexor carpi ulnaris tendon [37].

Ligaments¶

• The scapholunate interosseous ligament (SLIL) is the primary stabilizer of the scapholunate joint [55].
• The SLIL is composed of a proximal membranous portion with no significant strength, a dorsal portion that is the strongest and prevents translation, and a palmar portion that acts as a rotational constraint [55].
• The SLIL is C-shaped in the sagittal plane, with the dorsal third being the thickest and strongest portion [37].
• The volar portion of the lunotriquetral ligament is the thickest [37].
• The radioscapholunate ligament (ligament of Testut) is a volar intra-articular neurovascular structure that provides little mechanical stability [55].
• The radioscaphocapitate ligament, long radiolunate ligament, and short radiolunate ligament are palmar stabilizers considered secondary stabilizers of the scaphoid [55].
• The dorsal radiocarpal ligament and dorsal intercarpal ligament serve as dorsal stabilizers of the scaphoid [55].
• The triangular fibrocartilage complex (TFCC) is formed by the central meniscus homolog, dorsal and volar radioulnar ligaments, the floor of the extensor carpi ulnaris tendon sheath, and volar ulnocarpal ligaments [37].
• The dorsal and volar radioulnar ligaments are the primary stabilizers of the distal radioulnar joint [37].
• Only the peripheral 10% to 40% of the volar, ulnar, and dorsal TFCC has a vascular supply [37].

Kinematics and Biomechanics¶

• The wrist functions as a two-joint system linking the hand to the forearm around the mobile proximal carpal row [38].
• The proximal carpal row has no muscular or tendinous attachments and is an intercalary segment [37].
• With axial loading through the neutral wrist, approximately 80% of forces are transmitted through the distal radius (60% scaphoid facet, 40% lunate facet) and 20% through the distal ulna [37].
• With wrist flexion, 60% of the motion is midcarpal and 40% is radiocarpal [37].
• With wrist extension, 33% of the motion is midcarpal and 66% is radiocarpal [37].
• The dart-thrower’s path of radial extension to ulnar flexion defines the transition between flexion and extension of the scaphoid and lunate [38].
• Dart-thrower’s motion occurs almost exclusively through the midcarpal joint [38].

SLAC Pathophysiology¶

• Scapholunate interosseous ligament injury and extrinsic ligament complex attenuation lead to palmar flexion of the scaphoid and extension of the lunate (DISI) [12].
• The radioscaphoid joint becomes incongruous following SLIL injury, leading to altered radioscaphoid contact forces and development of arthrosis [12].
• The radiolunate joint is typically spared in SLAC wrist because of its spheroid shape [12].
• Carpal malalignment in SLAC wrists extends to the third carpometacarpal joint, with malalignment evident in both the sagittal and coronal planes [17].

SNAC Pathophysiology¶

• Scaphoid nonunion advanced collapse (SNAC) shares a common etiology with SLAC: proximal carpal row disruption leading to a dramatic alteration of carpal kinematics [4].
• In SNAC, the proximal scaphoid fragment remains attached to the lunate via the intact SLIL, whereas the distal fragment acts freely without restraint [4].
• SNAC demonstrates lunate dorsal tilt early in the disease, yet the articulation between the distal radius and the lunate remains preserved [4].
• SNAC wrists differ from SLAC wrists in exhibiting a decreased sagittal lunotriquetral angle, indicating a distinct pathomechanism of carpal instability [5].
• The distal scaphoid articular surface with the radial styloid is affected first in stage I of SNAC [12].
• The proximal scaphoid pole and radioscaphoid fossa may be preserved in stage I SNAC [12].

Clinical Presentation¶

• SLAC wrist symptoms include reduced grip and pinch strength [12].
• SLAC wrist symptoms include stiffness with extension and radial deviation [12].
• Localized tenderness at the radioscaphoid articulation is a symptom of SLAC wrist [12].
• Decreased wrist motion on extension and radial deviation is a symptom of SLAC wrist [12].
• A positive Watson shift test occurs when pressure directed over the palmar scaphoid tuberosity while moving the wrist from ulnar to radial deviation causes the scaphoid to subluxate dorsally out of the scaphoid fossa and relocate when pressure is released [12].

Classification¶

SLAC Wrist¶

• The Watson and Ballet classification of SLAC wrist osteoarthritis is widely accepted, simple, and a well-recognized guide to treatment [30].
• The Watson and Ballet classification of SLAC wrist osteoarthritis has significant limitations [30].
• Radiographic classification of SLAC wrist has moderate reliability and reproducibility [9].
• Carpal malalignment in SLAC wrists affects the radio- and midcarpal joints [17].
• Carpal malalignment in SLAC wrists extends to the third carpometacarpal joint [17].
• Malalignment in SLAC wrists is evident in both the sagittal and coronal planes [17].

SNAC Wrist¶

• In SNAC, the proximal scaphoid fragment remains attached to the lunate via the intact scapholunate interosseous ligament (SLIL) [4].
• In SNAC, the distal scaphoid fragment acts freely without restraint [4].
• Vender et al. staging for SNAC includes arthritis involving the articulation between the radial styloid and distal scaphoid fragment [4].
• Vender et al. staging for SNAC includes arthritis involving the articulation between the proximal scaphoid fragment and capitate [4].
• Vender et al. staging for SNAC includes arthritis involving the capitolunate articulation [4].
• Whether or not the radiolunate joint degenerates, comprising a fourth stage of SNAC, is debated [4].
• SNAC demonstrates lunate dorsal tilt early in the disease [4].
• The articulation between the distal radius and the lunate remains preserved in SNAC [4].
• Differentiating between SLAC and SNAC is important because treatment options may differ [4].
• SNAC wrists exhibit a decreased sagittal lunotriquetral angle compared to SLAC wrists [5].
• The decreased sagittal lunotriquetral angle in SNAC indicates a distinct pathomechanism of carpal instability [5].
• Bone density was greater at the capitolunate joint in SNAC wrists compared to controls [7].
• Bone density was greater at the radial styloid in SNAC wrists compared to controls [7].
• Bone density was greater at the radiolunate joint in SNAC wrists compared to controls [7].
• Radiographic classification of SNAC wrist has limited reliability [9].
• Staging systems for SNAC wrist lack agreement [16].
• The classification of Vender et al. (1987) is still widely used today to describe SNAC severity [22].
• The inter- and intra-observer reliability of the Vender et al. (1987) classification is poor [22].

Differential Diagnosis¶

• Scaphoid nonunion collapse was first described by Vender et al. in a series of 64 patients who demonstrated a similar degenerative pattern as SLAC in the setting of a chronic scaphoid nonunion [4].
• SOAC staging system can guide treatment decisions [19].
• SOAC is differentiated from SLAC wrist [19].

Clinical Presentation¶

Symptoms and Physical Examination¶

• Reduced grip and pinch strength is a symptom of SLAC wrist [12].
• Stiffness with extension and radial deviation is a symptom of SLAC wrist [12].
• Preoperatively, patients with SLAC or SNAC wrists complained of severe pain interfering with manual activities [20].
• Mean preoperative pain values in a cohort of SLAC and SNAC wrists were 78 under stress and 45 under resting conditions [20].

Etiology and Demographics¶

• Scaphoid nonunion advanced collapse (SNAC) is caused by trauma [8].
• SLAC wrist may result from chronic pseudogout and can appear bilaterally without a clear history of injury [8].
• Patients with SLAC wrist were more likely to be male and have a history of trauma compared to patients with first CMC OA [15].
• In a cohort of 36 patients undergoing midcarpal arthrodesis for SLAC or SNAC wrist, 14 had a major work-related injury, 14 had a major injury outside work, and 6 had no history of trauma [20].

Pathophysiology and Anatomy¶

• Scapholunate interosseous ligament injury and extrinsic ligament complex attenuation lead to palmar flexion of the scaphoid and extension of the lunate (DISI) in SLAC wrist [12].
• The radioscaphoid joint becomes incongruous in SLAC wrist, leading to alteration in normal radioscaphoid contact forces and development of arthrosis [12].
• As the scaphoid flexes and the scapholunate diastasis increases in SLAC wrist, the capitate migrates proximally [12].
• Altered intercarpal contact forces in SLAC wrist result in arthrosis at the capitolunate joint [12].
• SNAC shares a common etiology with SLAC: proximal carpal row disruption leading to a dramatic alteration of carpal kinematics [4].
• SNAC wrists exhibit a decreased sagittal lunotriquetral angle compared to SLAC wrists, indicating a distinct pathomechanism of carpal instability [5].
• Carpal malalignment in SLAC wrists affects the radio- and midcarpal joints and extends to the third carpometacarpal joint, with malalignment evident in both the sagittal and coronal planes [17].

Staging and Classification¶

• The Watson and Ballet classification of SLAC wrist osteoarthritis is widely accepted, simple, and a well-recognized guide to treatment despite its significant limitations [30].
• Vender et al's staging for SNAC includes arthritis involving the articulation between the radial styloid and distal scaphoid fragment, the articulation between the proximal scaphoid fragment and capitate, and the capitolunate articulation [4].

Investigations¶

Radiographic Assessment and Staging¶

• Radiographic classification of SLAC wrist demonstrates moderate reliability and reproducibility [9].
• Radiographic classification of SNAC wrist demonstrates limited reliability [9].
• The Watson classification for SLAC wrist Stage I is characterized by arthrosis localized to the radial side of the scaphoid and the radial styloid, along with sharpening of the radial styloid [12].
• The Watson classification for SLAC wrist Stage II is characterized by arthrosis of the entire radioscaphoid joint, with the radiolunate joint usually spared [12].
• The Watson classification for SLAC wrist Stage III is characterized by arthrosis progressing to the capitolunate joint due to proximal migration of the capitate [12].
• In SNAC wrist Stage I, the distal scaphoid articular surface with the radial styloid is affected first, while the proximal scaphoid pole and radioscaphoid fossa may be preserved [12].
• Vender et al. described a degenerative pattern in SNAC involving arthritis at the articulation between the radial styloid and distal scaphoid fragment, the articulation between the proximal scaphoid fragment and capitate, and the capitolunate articulation [4].
• Whether radiolunate joint degeneration constitutes a fourth stage of SNAC is debated [4].
• SNAC wrists demonstrate lunate dorsal tilt early in the disease, yet the articulation between the distal radius and the lunate remains preserved [4].
• A 10° degree of supination can drastically alter the developed posteroanterior radiograph of the wrist [26].

Advanced Imaging (CT, MRI, Arthroscopy)¶

• Bone density is greater at the capitolunate joint, the radial styloid, and the radiolunate joint in SNAC wrists compared to controls [7].
• MRI is useful for detecting marrow abnormalities in osteonecrosis of the scaphoid following fracture [42].
• Asymmetry of marrow signal in proximal and distal fragments of a fractured scaphoid on MRI is suggestive of proximal pole ischemia [42].
• Wrist arthroscopy is considered the "gold standard" for the evaluation of intercarpal ligament injuries and instability [43].
• Arthroscopy has been found to be more accurate than arthrography in identifying the location and size of triangular fibrocartilage and interosseous ligament injuries [43].
• Arthroscopy is more accurate than triple-injection cinearthrography in detecting tears of the dorsal sensory branch of the ulnar nerve during arthroscopic repair of the triangular fibrocartilage [43].
• The dorsal rim of the radial styloid is a common site of early SNAC and SLAC wrist changes and should be assessed in all cases at arthroscopic surveillance [11].
• Associated synovitis in the radial styloid area may obscure visualization of the cartilage during arthroscopy [11].

Clinical Examination¶

• The Watson shift test involves directing pressure over the palmar scaphoid tuberosity while moving the wrist from ulnar to radial deviation [12].
• A positive Watson shift test results when the scaphoid subluxates dorsally out of the scaphoid fossa and relocates when pressure is released [12].
• Symptoms of SLAC wrist include reduced grip and pinch strength [12].
• Symptoms of SLAC wrist include stiffness with extension and radial deviation [12].
• Symptoms of SLAC wrist include localized tenderness at the radioscaphoid articulation [12].
• Symptoms of SLAC wrist include decreased wrist motion on extension and radial deviation [12].

Nuclear Medicine¶

• Fifteen-minute bone scintigraphy is useful as a second-line investigation for continuing wrist pain following trauma in the presence of normal radiography [63].

Treatment¶

Non-Operative and Diagnostic Considerations¶

• Diagnostic arthroscopy is indicated for the staging of posttraumatic arthritis, including SLAC and SNAC wrists [27].

Arthroscopic Debridement and Styloidectomy¶

• Arthroscopic radial styloidectomy is indicated for stage I SLAC and SNAC wrist conditions [11].
• Arthroscopic radial styloidectomy may be performed as an isolated procedure or as an adjunct to scaphoid non-union or scapholunate reconstruction procedures [31].
• The recommended depth of arthroscopic radial styloidectomy resection is no more than 3–4 mm to avoid increased radial translation and ulnar/palmar carpal displacement [11].
• Arthroscopic wrist debridement and radial styloidectomy may relieve pain while preserving wrist motion for SLAC stage 2 or 3 disease [33].
• Overaggressive arthroscopic radial styloidectomy may cause injury to the radioscaphocapitate (RSC) and lunotriquetral ligament (LRL) ligaments, leading to instability [31].
• Injury to the sensory branch of the radial nerve is a potential complication at the 1-2 portal during arthroscopic radial styloidectomy [31].

Distal Scaphoid Resection¶

• Arthroscopic distal scaphoidectomy is indicated for symptom control in selected cases of SNAC wrist [54].
• Distal scaphoid resection is a durable procedure with good long-term results, with 94% of patients remaining satisfied and no further wrist collapse or radiocarpal arthritis developing [24].
• The best indication for distal scaphoidectomy in SNAC wrist is when cartilage degeneration, osteophyte formation, and deformity are confined mainly to the distal scaphoid articular surface [54].
• A significant dorsal lunate tilt deformity (DISI) is considered a relative contraindication to distal scaphoid excision [54].
• Marked arthritis at the lunocapitate joint constitutes a relative contraindication to distal scaphoid excision [54].
• In dorsal type scaphoid nonunion, simulated distal fragment resection aggravates pressure concentration around the capitate head, indicating a potential risk for worsening preexisting lunocapitate arthritis [54].

Scaphoid Reconstruction¶

Partial Wrist Fusion and Arthrodesis¶

• Partial wrist fusion is indicated for painful posttraumatic and osteoarthritic conditions of the wrist, including SLAC and SNAC wrists, in patients seeking pain control while preserving useful motion [10].
• Chronic smokers have a higher incidence of nonunion following partial wrist fusion [10].
• Midcarpal arthrodesis is a reliable procedure for treating SLAC- and SNAC-wrists in stages II and III that preserves some range of motion [1].
• Four-corner fusion retains 60% of wrist motion and 80% of grip strength [12].
• Capitolunate arthrodesis is a satisfactory therapeutic alternative to four-corner fusion for SNAC wrist with osteoarthritis [51].
• Capitolunate arthrodesis using headless compression screws allows for a higher union rate, short operative time, and short rehabilitation period [51].
• Trapeziometacarpal joint arthritis and SLAC wrist may be treated either simultaneously or in stages [23].

Proximal Row Carpectomy (PRC)¶

• Proximal row carpectomy (PRC) provides improvements in pain and subjective outcome measures for patients with symptomatic and appropriately staged SLAC or SNAC wrists [2].
• PRC is indicated for stage II SLAC wrist, with the disadvantage of reduced wrist motion and grip strength [12].
• PRC should be avoided if there are capitate head degenerative changes [12].
• Limited carpal fusion is favored over proximal row carpectomy for SNAC and SLAC wrist conditions, except for flexion-extension and grip strength in women [3].
• Proximal row carpectomy is preferred for SLAC wrists with preserved capitate head cartilage due to socio-economic benefits, lower complication rates, and procedural ease [29].

Complications¶

• The potential advantage of partial wrist fusion in preservation of a useful arc of motion may be offset by the risks of nonunion [10].
• The potential advantage of partial wrist fusion in preservation of a useful arc of motion may be offset by continued pain despite successful fusion [10].
• Patients with preexisting extensor tendon pathology over the wrist region may have a higher incidence of tendon complications associated with complex partial wrist fusion procedures [10].
• Arthrofibrosis and long-standing carpal collapse may pose additional difficulty and risk for partial wrist fusion [10].
• Resection of 6 mm and 10 mm of the radial styloid was associated with radial, ulnar, and palmar carpal displacement [22].
• Resection of 3 mm of the radial styloid was not associated with radial, ulnar, and palmar carpal displacement [22].
• In a series of 43 patients undergoing midcarpal arthrodesis and complete scaphoid excision, total wrist arthrodesis was subsequently required in two patients to relieve severe pain [20].
• In a series of 43 patients undergoing midcarpal arthrodesis and complete scaphoid excision, one patient required a revision midcarpal fusion with additional bone grafting [20].
• In a series of 43 patients undergoing midcarpal arthrodesis and complete scaphoid excision, four patients reported moderate pain postoperatively [20].
• In a series of 43 patients undergoing midcarpal arthrodesis and complete scaphoid excision, four patients felt that they were not improved postoperatively [20].

Recovery¶

• Midcarpal arthrodesis preserves some range of motion in patients with SLAC- and SNAC-wrists in stages II and III [1].
• Distal scaphoid resection is a durable procedure with good long-term results [24].
• 94% of patients remained satisfied after distal scaphoid resection for arthritis secondary to scaphoid nonunion [24].
• No further wrist collapse or radiocarpal arthritis developed in patients treated with distal scaphoid resection for arthritis secondary to scaphoid nonunion [24].
• Functional results were good at long-term follow-up for 4-corner fusion in SLAC and SNAC wrists despite radiographic changes in the radiolunate joint in 73% of patients [62].

Key Evidence¶

• [L4] Our data demonstrate that midcarpal arthrodesis is a reliable procedure for treating SLAC- and SNAC-wrists in stages II and III and, furthermore, one which preserves some range of motion. [1] (10.1097/01.sap.0000194245.94684.54)
• [L4] Both procedures provide improvements in pain and subjective outcome measures for patients with symptomatic and appropriately staged SLAC or SNAC wrists. [2] (10.1177/1753193408100954)
• [L3] Among patients treated for SNAC and SLAC wrist conditions, findings are in favour of Limited Carpal Fusion compared to Proximal Row Carpectomy, except for flexion-extension and grip strength in women. [3] (10.1186/s13018-023-04177-7)
• [L5] [4] (10.1016/j.jhsa.2015.06.110)
• [L4] SNAC wrists differ from SLAC wrists in exhibiting a decreased sagittal lunotriquetral angle, indicating a distinct pathomechanism of carpal instability. [5] (10.1186/s12891-025-08652-6)
• [L4] Scaphoid excision and four-corner fusion is indicated for the treatment of the SLAC/SNAC wrist when significant pain is refractory to nonoperative measures. [6] (10.1053/otor.2003.36321)
• [L3] Bone density was greater at the capitolunate joint, the radial styloid, and the radiolunate joint in SNAC wrists compared to controls. [7] (10.2106/jbjs.22.01350)
• [L5] [8] (10.1016/j.jhsa.2011.01.018)
• [L4] Radiographic classification of SLAC wrist has moderate reliability and reproducibility, whereas classification of SNAC wrist has limited reliability. [9] (10.1177/1753193413484629)
• [L4] Successful scaphoid reconstruction in SNAC wrists shifts the load back onto the proximal pole and interrupts the otherwise inevitable degenerative pattern in scaphoid nonunions. [13] (10.1016/j.jhsa.2018.06.104)
• [L4] It is mostly indicated as a palliative procedure in elderly patients with posttraumatic SNAC or SLAC wrist with limited functional demands. [14] (10.1055/s-0032-1329615)
• [L3] Patients with SLAC wrist were more likely to be male and have a history of trauma compared to patients with first CMC OA. [15] (10.1177/1558944718788672)
• [Paper] Staging systems for SNAC wrist lack agreement. [16] (10.1007/s12593-012-0062-2)
• [L3] Carpal malalignment in SLAC wrists not only affects the radio- and midcarpal joints, but also extends to the third carpometacarpal joint, with malalignment evident in both the sagittal and coronal planes. [17] (10.1016/j.jhsa.2024.09.021)
• [L4] It also differentiates SOAC from SLAC wrist and discusses how the SOAC staging system can guide treatment decisions. [19] (10.5435/jaaos-d-25-01408)
• [L4] [20] (10.1054/jhsb.2000.0434)
• [L4] The procedure is indicated for SLAC II or SLAC III wrists as an intermediate step to relieve pain and preserve functional motion. [21] (10.1016/j.arthro.2012.04.108)
• [L3] [22] (10.1177/1753193417739519)
• [L4] Trapeziometacarpal joint arthritis and SLAC wrist may be treated either simultaneously or in stages. [23] (10.1016/j.jhsa.2021.05.002)
• [L4] Distal scaphoid resection is a durable procedure with good long-term results. 94% of patients remained satisfied, and no further wrist collapse or radiocarpal arthritis developed. [24] (10.1016/s0363-5023(11)60002-6)
• [Paper] Our results highlight the significant effect of rotation on radiographic landmarks at the wrist, indicating that 10° of supination can drastically alter the developed radiograph. [26] (10.1177/15589447241255705)
• [L3] The authors prefer proximal row carpectomy for SLAC wrists with preserved capitate head cartilage due to socio-economic benefits, lower complication rates, and procedural ease. [29] (10.1177/1753193408087116)
• [L5] Despite its significant limitations, the Watson and Ballet classification of SLAC wrist osteoarthritis is widely accepted, simple, and a well-recognized guide to treatment. [30] (10.1097/corr.0000000000000451)
• [L4] The procedure studied may have advantages in relieving pain while preserving wrist motion for SLAC stage 2 or 3 disease. [33] (10.1177/1558944717725383)
• [Paper] [51] (10.1007/s12593-015-0182-6)
• [L4] ARARC may be a viable surgical option for patients with SLAC wrist who desire a minimally invasive procedure. [58] (10.1055/s-0034-1373839)
• [L4] Functional results were good at long-term follow-up despite radiographic changes in the radiolunate joint in 73% of patients. [62] (10.1177/1558944716681949)
• [L4] We find this rapid version of the bone scan useful as a second line investigation for continuing wrist pain following trauma in the presence of normal radiography. [63] (10.1016/s0020-1383(99)00280-6)

References¶

[1] Long-Term Results of Midcarpal Arthrodesis in the Treatment of Scaphoid Nonunion Advanced Collapse (SNAC-Wrist) and Scapholunate Advanced Collapse (SLAC-Wrist). Annals of Plastic Surgery. 2006. DOI: 10.1097/01.sap.0000194245.94684.54

[2] Proximal Row Carpectomy vs Four Corner Fusion for Scapholunate (Slac) or Scaphoid Nonunion Advanced Collapse (Snac) Wrists: A Systematic Review of Outcomes. Journal of Hand Surgery (European Volume). 2009. DOI: 10.1177/1753193408100954

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