Introduction
Chronic, non-traumatic wrist pain is a diagnostic challenge in both primary care and musculoskeletal clinics. Scapholunate ligament injuries are often missed but are common.
A missed scapholunate ligament (SLL) tear can progress to carpal malalignment (Dorsal Intercalated Segment Instability – DISI) and ultimately a Scapholunate Advanced Collapse (SLAC) wrist, an irreversible pattern of degenerative arthritis.
Early recognition of the clinical cues that warrant imaging, and timely referral is therefore crucial.
Patient profile
A 42-year-old right-hand-dominant hotel front-of-house manager and recreational golfer/padel player presented with a 4-month history of sharp radial dorsal right-wrist pain, worsened by gripping, lifting and desk work.
He recalled no definite recent trauma but, on careful questioning, remembered a fall on the wrist 15 years earlier while playing football.
Since then, he had only had minimal discomfort until the most recent episode. Now, pain limited golf, gym work and even hand-shakes. Self-directed ice, compressive wraps and physiotherapy-led strengthening had exacerbated symptoms.
Examination pearls
- Visible, diffuse swelling over the dorsal radial wrist
- Tenderness at the scaphoid tuberosity, radius-scaphoid joint.
- Painful resisted thumb extension/abduction and reduced grip strength; global wrist range of motion otherwise preserved
- Positive Watson test (painful clunk on scaphoid shift) – highly suggestive of SLL injury
- Neurovascular status normal
- No ulnar sided signs or symptoms
Key points leading to decision to image
- Localised wrist pain persisting >6 weeks despite conservative care
- Dorsal swelling over scapholunate interval with painful Watson test
- History of earlier fall on the out-stretched hand with ongoing discomfort
- Suspicion of carpal row effusion on ultrasound
Investigations for SLAC
| Modality | Key findings | Indications / Learning point |
|---|---|---|
| Point-of-care ultrasound | Effusion over proximal carpal row, dorsal soft-tissue swelling, intact extensor compartmentsInability to visualise the SLL | Carpal joint effusion should raise suspicion for an intra-articular driver and prompt MRI |
| MRI (1.5 T, non-arthrogram) | • Full-thickness SL ligament tear with >4 mm SL gap • ↑ SL angle (>80°) = DISI pattern • Early radioscaphoid osteochondral change + capitate proximal migration = Stage I–II SLAC • Dorsal capsulitis, multiple dorsal ganglia | MRI is radiological gold standard for soft-tissue detail and staging in chronic SLL injury |
Plain PA & lateral radiographs (requested post-MRI) demonstrated SL diastasis of 4.5 mm and an SL angle of 82°, corroborating DISI alignment.
Sagittal MRI of our patient on the left clearly demonstrating DISI, normal wrist MRI on the right (from radiopaedia)
Initial diagnosis
Chronic scapholunate ligament rupture with dorsal inter-calated segment instability and early (Stage II) SLAC wrist.
Initial management of SLAC
The patient was counselled to cease boxing/golf and was fitted with a removable short-arm wrist splint. Given the structural instability and arthrosis, he was referred to a wrist surgeon for discussion of surgical management.
Discussion points
1. Pathomechanics of DISI and SLAC
The SLL resists flexion of the scaphoid and helps the lunate follow. Complete rupture allows the scaphoid to flex volarly while the lunate tips dorsally under the pull of the triquetrum, producing a DISI pattern (SL angle >60°; radiolunate angle >30°).
Unchecked, abnormal kinematics concentrate load across the radioscaphoid joint; progressive chondral wear propagates in a predictable manner (Watson’s SLAC stages):
| SLAC Stage | Degeneration pattern | Typical radiograph |
|---|---|---|
| I | Radioscaphoid fossa | Narrowed radioscaphoid space, osteophytes |
| II | Entire radioscaphoid + radial lunate facet | Carpal collapse, capitate proximal migration |
| III | Capitolunate joint | Pan-carpal arthritis |
| IV | Radiolunate joint (rare) | Global radiocarpal arthritis |
2. Clinical cues not to miss
- Dorsal wrist swelling + localised SL tenderness
- Painful “click & clunk” during loaded wrist extension (push-ups, golf swing)
- Reduced grip force out of proportion to normal ROM
- Failure to progress after 6 weeks of targeted rehab
If plain films are initially normal but suspicion remains high, proceed to MRI or CT-arthrogram. Early arthroscopy can both confirm diagnosis and allow thermal-shrinkage or capsulodesis before cartilage loss.
3. Treatment algorithm for SLL complete tear
Whilst partial injuries can most often be managed with immobilisation and subsequent rehabilitation, complete tears will need surgery.
Acute (<3 weeks) – open/arthroscopic primary SL repair ± dorsal capsulodesis.
Subacute (3 weeks–6 months) – ligament reconstruction using three-ligament tenodesis (FCR graft), SL screw or suture-bridge augmentation.
Chronic with arthritis (SLAC) – Stage I–II: radial styloidectomy ± ligament reconstruction; Stage III: proximal row carpectomy or four-corner fusion; Stage IV: total wrist arthrodesis or arthroplasty.
After arthroscopy, the diagnosis for our patient was confirmed to be a stage III SLAC, and a four-corner fusion was recommended.
Key learning points
- Ask about historic FOOSH even in “atraumatic” presentations – patients often minimise old injuries.
- Watson test pain ± dorsal swelling should lower the threshold for imaging.
- Ultrasound-visualised effusion in context of injury is a red flag for intra-articular pathology.
- Once SL angle > 60° or gap > 3 mm is seen, refer promptly to a wrist surgeon; delayed repair markedly worsens outcomes.
- Early recognition may allow ligament reconstruction and avoid progression to salvage procedures required in SLAC wrist.
References
- Garcia-Elias M, Lluch A, Stanley JK. Three-ligament tenodesis for scapholunate dissociation. J Hand Surg Am.2006;31:125-134.
- Weiss KE, Rodner CM. Scapholunate advanced collapse (SLAC) wrist. J Am Acad Orthop Surg. 2007;15:648-659.
- Herzberg G, Comtet JJ, Linscheid RL, et al. Perilunate injuries: classification and natural history. J Hand Surg Am. 1993;18:768-779.
- Bain GI, Begg M. Surgical management of scapholunate instability. J Wrist Surg. 2019;8:123-134.
- Patel NK, Ilyas AM. Dorsal intercalated segment instability. Hand Clin. 2020;36:301-311.
- Rettig AC. Wrist arthroscopy for scapholunate ligament injuries. Arthroscopy. 2013;29:268-276.
- Watson HK, Ballet FL. The SLAC wrist: scapholunate advanced collapse pattern of degenerative arthritis. J Hand Surg Am. 1984;9:358-365.
- Beadel GP, Bain GI, Smith P. Radiographic analysis of carpal collapse patterns: DISI and VISI. J Hand Surg Am.2005;30:896-903.
