Progressive Instability | Mayfield Stages | Emergent Reduction | Ligament Reconstruction
- 25% missed initially - always look for carpal arc disruption on lateral X-ray
- Spilled teacup sign = Stage IV lunate dislocation (lunate tips volar into carpal tunnel)
- Mayfield progression: SL then capitolunate then lunotriquetral ligaments fail sequentially
- Acute median nerve symptoms common in Stage IV - urgent reduction required
- Greater arc injuries = fracture-dislocations (trans-scaphoid most common)
- “Lateral X-ray: Lunate should articulate with both radius and capitate
- “Lesser arc = pure ligamentous; Greater arc = bone fractures
- “Trans-scaphoid perilunate = scaphoid fracture + perilunate dislocation
- “Open reduction via combined volar + dorsal approach preferred
One quarter of perilunate/lunate dislocations are missed on initial presentation. Always examine the lateral X-ray carefully - the lunate should articulate with both the radius and the capitate.
Sequential ligament failure: Scapholunate (I) then capitolunate (II) then lunotriquetral (III) then lunate tips volar (IV). Understanding this helps identify the stage and predict associated injuries.
Acute carpal tunnel syndrome is common across perilunate injuries (acute median neuropathy in ~47%; Wickramasinghe 2015) and is especially associated with volar lunate dislocation (Stage IV). The volarly dislocated lunate compresses the median nerve. Urgent reduction is critical to relieve sustained compression.
Lesser arc = pure ligamentous injury around lunate. Greater arc = fractures through bones (trans-scaphoid most common). Greater arc injuries have better bone healing but worse overall outcomes.
Overview
Perilunate and lunate dislocations represent a spectrum of high-energy carpal injuries characterized by progressive failure of the perilunate ligamentous structures. These injuries are frequently missed on initial presentation (up to 25% of cases), leading to delayed diagnosis and poorer outcomes.
The mechanism involves forced hyperextension, ulnar deviation, and intercarpal supination, typically from a fall on an outstretched hand with the wrist in dorsiflexion. The injury progresses through predictable stages (Mayfield classification) as sequential ligaments fail.
Key Concepts:
- Perilunate dislocation: Lunate remains articulated with radius; carpus dislocates dorsally around it
- Lunate dislocation: Lunate dislocates volarly while proximal carpal row reduces
- Both are part of a continuous spectrum of progressive perilunar instability
- Associated fractures (greater arc) are common, especially scaphoid
Anatomy
Perilunate Ligamentous Anatomy
The lunate is the keystone of the proximal carpal row, with critical ligamentous attachments:
- Scapholunate ligament: Strongest dorsally, key stabilizer
- Lunotriquetral ligament: Strongest volarly
- Both critical for carpal stability
- Volar radiocarpal ligaments: RSC (radioscaphocapitate), LRL (long radiolunate), SRL (short radiolunate)
- Dorsal radiocarpal ligaments: DRC (dorsal radiocarpal)
- Space of Poirier: Weak zone between RSC and LRL - path of lunate dislocation
Greater Arc vs Lesser Arc
- Injury passes through ligaments only
- Arc around the lunate through SL, capitolunate space, LT ligament
- Pure soft tissue injury
- More challenging reconstruction
- Injury passes through bones
- Common fracture patterns:
- Trans-scaphoid (most common)
- Trans-radial styloid
- Trans-capitate
- Trans-triquetral
- Bone healing potentially easier than ligament healing
Distinct from the Mayfield perilunate spectrum are the rare axial (longitudinal) carpal dislocations - the carpus splits longitudinally into columns rather than dislocating around the lunate:
- Mechanism: a severe crush/blast injury to the dorsopalmar plane of the hand (industrial press, run-over) drives the metacarpals and carpus apart along the long axis, disrupting the transverse intercarpal and intermetacarpal ligaments.
- Garcia-Elias classification by the column displaced: axial-radial (radial column - thumb/index ray and adjacent carpus - displaces radially, peritrapezial/peri-scaphoid-trapezial), axial-ulnar (ulnar column - small/ring ray, peri-pisiform/peri-hamate - displaces ulnarly), and combined axial-radial-ulnar (a central column retained between two diverging columns).
- Why they matter: they are high-energy crush injuries with major soft-tissue, neurovascular (ulnar/median branches), tendon and skin compromise - the soft-tissue injury, compartment syndrome and contamination dominate the prognosis far more than the bony dislocation.
- Management: emergency debridement, compartment release if needed, anatomic realignment of the columns with K-wire/screw fixation, and staged soft-tissue/neurovascular reconstruction - very different from the perilunate algorithm.
Exam point: if asked about carpal dislocations beyond the perilunate spectrum, name the axial (longitudinal) carpal dislocation - a crush-injury longitudinal split of the carpus (Garcia-Elias axial-radial / axial-ulnar / combined) where the soft-tissue injury, not the bony dislocation, drives the outcome.
Pathophysiology
Mechanism of Injury
- Fall on outstretched hand (FOOSH)
- Wrist in dorsiflexion
- Combined hyperextension + ulnar deviation + intercarpal supination
- High-energy trauma (MVA, fall from height, sports)
- Axial load through palm
- Ground reaction force applied to thenar eminence
- Wrist forced into hyperextension
- Sequential ligament failure from radial to ulnar side
Perilunate injuries frequently cause acute median neuropathy (reported in approximately 47% across the spectrum; Wickramasinghe 2015), and acute carpal tunnel syndrome is especially associated with volar lunate dislocation (Stage IV) where the displaced lunate directly compresses the median nerve. Emergent reduction is required - prolonged sustained nerve compression risks permanent damage.
Classification Systems
Mayfield Progressive Perilunar Instability
The Mayfield classification describes the sequential failure of perilunate structures.
Disruption of scapholunate interosseous ligament. Scaphoid flexes, lunate extends (DISI pattern begins). Widened SL interval on PA X-ray (greater than 3mm). Terry Thomas sign (gap between scaphoid and lunate).
Space of Poirier disrupts (between RSC and LRL ligaments). Capitate dislocates dorsally relative to lunate. Lunate still articulates with radius. Progressive ligament failure continues.
Lunotriquetral ligament fails. Entire carpus dislocates dorsally around lunate. Lunate remains in lunate fossa of radius (key point). Capitate no longer articulates with lunate. Lateral X-ray shows dorsal capitate displacement.
Dorsal radiocarpal ligament fails (final ligament). Lunate rotates and tips volarly out of lunate fossa. Lunate enters carpal tunnel ("spilled teacup"). Acute median nerve compression is common across the perilunate spectrum (reported in approximately 47% of all perilunate injuries; Wickramasinghe 2015) and is especially associated with volar lunate dislocation. Surgical emergency if nerve symptoms present.
- What it is: in a volar (palmar) perilunate dislocation the capitate and distal carpus dislocate volarly relative to the lunate (which stays in the fossa) - the mirror image of the common dorsal perilunate dislocation. (Do not confuse it with a Stage IV lunate dislocation, where the lunate itself tips volar into the carpal tunnel.)
- Mechanism: a less typical force - a dorsally-directed blow on the flexed/palmar-flexed wrist (rather than the usual hyperextension-ulnar deviation-supination), so the carpus is driven palmar to the lunate.
- Why it is important: it is easily missed (even rarer than the dorsal pattern, so unfamiliar), still follows the same emergency-reduction-then-operative-repair principle, and the reduction manoeuvre is reversed (the carpus is reduced from volar back to dorsal).
- The teaching point: a perilunate dislocation can go either way - always define the direction of carpal displacement relative to the lunate on the true lateral before planning reduction.
Exam point: ~97% of perilunate dislocations are dorsal; the rare volar (palmar) perilunate dislocation (carpus displaced volar to an in-fossa lunate) is the mirror-image exception, from a dorsal blow on a flexed wrist, reduced by the reverse manoeuvre - distinct from a Stage IV lunate dislocation.
Clinical Assessment
History
- High-energy trauma typically
- Fall on outstretched hand
- Motor vehicle accident
- Sports injury (contact sports, cycling)
- Severe wrist pain
- Rapid swelling
- Inability to move wrist
- Numbness in median nerve distribution (especially Stage IV)
- History may include feeling of "pop" or "shift"
Physical Examination
- Marked swelling of wrist
- Loss of normal wrist contour
- May see dorsal prominence (perilunate) or volar fullness (lunate)
- Skin tension assessment critical
- Diffuse tenderness
- Possible palpable lunate volarly (Stage IV)
- Assess for open injury or skin compromise
- Critical: Median nerve function assessment
- Sensation in thumb, index, middle finger
- Thenar muscle strength (opponens pollicis)
- Two-point discrimination
- Compare with contralateral side
- Severely limited due to pain
- Do not force examination
- Document baseline for postoperative comparison
Red Flags Requiring Emergent Intervention
- Acute carpal tunnel symptoms (numbness, tingling, weakness)
- Open injury
- Skin blanching or tension
- Vascular compromise
- Compartment syndrome signs
Differential Diagnosis
The painful, swollen, deformed wrist after a fall on the outstretched hand has several mimics. The single most important discriminator is the lateral radiograph: in a perilunate/lunate dislocation the normal radius-lunate-capitate colinearity is lost. Failure to make this distinction underlies the 25% missed-diagnosis rate (Herzberg 1993).
- Distinguishing Features
- High-energy FOOSH; gross swelling; median nerve symptoms common; loss of radius-lunate-capitate colinearity on lateral; disrupted Gilula's arcs on PA
- Management Pointer
- Emergent reduction then operative repair/fixation
- Distinguishing Features
- Common in all ages; dorsal/volar angulation at the metaphysis; carpal alignment preserved; lunate stays in fossa
- Management Pointer
- Closed reduction; cast or ORIF depending on stability
- Distinguishing Features
- Anatomical snuffbox tenderness; carpus aligned; no carpal dislocation; may be radiographically occult early
- Management Pointer
- Cast; ORIF for displaced/unstable; MRI if occult
- Distinguishing Features
- SL gap greater than 3 mm (Terry Thomas sign); DISI on lateral; carpus otherwise reduced; no full perilunate dislocation
- Management Pointer
- Acute repair / pinning; reconstruction if chronic
- Distinguishing Features
- Lower-energy mechanism; tenderness without bony or alignment abnormality; normal radiographs and Gilula's arcs
- Management Pointer
- Symptomatic; re-image or MRI if symptoms persist
- Distinguishing Features
- More insidious; sclerosis/collapse of lunate; no acute dislocation; chronic ulnar-negative association
- Management Pointer
- Staged management per Lichtman stage
Investigations
Plain Radiographs
Standard Views:
- PA (posteroanterior)
- True lateral
- Oblique views
PA View Findings:
Normal landmarks (Gilula's arcs):
- Arc I: Proximal articular surfaces of proximal row
- Arc II: Distal articular surfaces of proximal row
- Arc III: Proximal articular surfaces of capitate/hamate
Abnormal findings:
- Disruption of Gilula's arcs
- Widened SL interval (greater than 3mm = "Terry Thomas sign")
- Overlap or crowding of carpal bones
- Triangular or pie-shaped lunate = rotated lunate
Lateral View Findings:
Normal alignment:
- Radius, lunate, and capitate should be collinear
- Lunate "cup" should hold capitate "ball"
Perilunate dislocation (Stage III):
- Lunate remains in lunate fossa
- Capitate dislocated dorsally
- Lunate no longer articulates with capitate
Lunate dislocation (Stage IV):
- Lunate tilted volarly out of fossa
- "Spilled teacup" appearance
- Capitate may partially reduce into lunate fossa
On lateral X-ray, the lunate normally appears like a cup holding the capitate. In Stage IV lunate dislocation, the lunate rotates and "spills" volarly - the spilled teacup sign. This is pathognomonic for lunate dislocation.
CT Scan
- Confirm diagnosis
- Identify associated fractures (greater arc injuries)
- Pre-operative planning
- Assess reduction quality post-operatively
- Fracture lines in scaphoid, capitate, triquetrum, or styloid
- Extent of articular involvement
- Fragment size and displacement
MRI
- Usually not needed acutely
- May help assess ligament integrity subacutely
- Useful for planning staged reconstruction
- Ligament tears (SL, LT)
- Bone bruising pattern
- TFCC injury assessment
Management Algorithm
Initial Assessment and Closed Reduction
- Assess neurovascular status immediately (critical: median nerve function)
- Document mechanism of injury
- Assess skin integrity and tension
- Obtain PA, lateral, and oblique X-rays
- Splint in position of comfort initially
- Acute carpal tunnel syndrome (Stage IV lunate dislocation)
- Skin compromise or threatened skin
- Open injury
- Vascular compromise
- Traction: Apply longitudinal traction through fingers
- Recreate: Initially increase wrist extension to disengage and recreate deformity
- Apply pressure: Thumbs over dorsum, apply pressure over dorsal carpus
- Push and flex: Push carpus volarly while flexing wrist
- Verify reduction: Immediate post-reduction films
- Analgesia: Regional block or procedural sedation required
- Splint in neutral position
- Repeat neurovascular examination
- Confirm reduction on X-ray
- Arrange definitive surgery within 24-72 hours (within 7-14 days ideally)
Closed reduction is temporizing only. ALL perilunate/lunate dislocations require definitive surgical treatment. Closed treatment alone results in unacceptable rates of instability and arthritis.
Emergent open reduction in operating theater. Interposed tissue is preventing reduction.
Surgical Technique
Positioning and Preparation
- Supine position
- Arm on hand table
- Upper arm tourniquet applied
- Exsanguinate with elevation (avoid Esmarch if concern for fracture displacement)
Combined volar plus dorsal approach preferred for all perilunate/lunate dislocations. Volar approach performed first for carpal tunnel release and lunate visualization. Dorsal approach then used for definitive reduction and fixation. Single approach inferior to combined approach which provides better visualization and outcomes.
Complications
Early Complications
- Acute compression from displaced lunate (Stage IV)
- Iatrogenic during reduction
- Carpal tunnel syndrome post-operatively
- Usually improves with reduction and CTR
- Higher risk with open injuries
- Standard surgical infection risk
- Interposed tissue (capsule, tendons)
- Inadequate surgical technique
- May require repeat surgery
Late Complications
- Most common long-term complication
- Occurs in 50-70% at long-term follow-up
- May be asymptomatic
- Radiocarpal and midcarpal joints affected
- Recurrent SL or LT dissociation
- Progressive collapse patterns (SLAC, SNAC equivalent)
- May require salvage procedures
- In trans-scaphoid perilunate injuries
- Risk factors: Delay, inadequate fixation, smoking
- Requires revision surgery with bone grafting
- Rare but devastating
- Blood supply vulnerable during injury
- May lead to Kienböck's pattern
- Limited salvage options
- Expected to some degree
- ROM typically 50-70% of normal
- Grip strength 60-80% of normal
- Therapy critical for optimization
Complex Regional Pain Syndrome
- Rare but serious complication
- Early recognition and treatment essential
- Multidisciplinary approach required
Postoperative Care
Strict elevation, multimodal analgesia, and neurovascular checks every 2 hours initially - this injury carries acute median neuropathy in nearly half of cases (Wickramasinghe), so a nerve that was decompressed still needs watching and one that was not needs watching harder. Look for compartment syndrome: rare here but catastrophic. Finger range of motion starts immediately; the wrist is immobilised, the digits are not.
Volar splint or short arm cast with strict wrist immobilisation, continuing finger ROM throughout. First dressing change, wound check and suture removal at 2 weeks.
Continue immobilisation; a removable splint is reasonable for hygiene but there is no active wrist motion yet. K-wires stay in situ. Serial radiographs every 2 weeks - this is the window in which secondary loss of reduction declares itself, and it is the commonest complication of the whole injury (10.1% overall, and 24.2% after a PURE dislocation versus 7.0% after a fracture-dislocation, Liechti). The pure ligamentous injury is the one to watch hardest, which is counterintuitive.
Radiographs to confirm maintained reduction, K-wires out in clinic under local anaesthesia, and gentle active ROM begins with hand therapy. Avoid forceful grip or loading.
Therapist-supervised progressive ROM and gentle strengthening; heat before exercise is reasonable. Still protect from forceful loading.
Unrestricted ROM, progressive strengthening with weights, putty and grip work, and functional activity.
Light duty may be earlier; heavy labour typically 6 months minimum and sport by individual progress. Set the expectation early rather than at this visit: long-term ROM around 50-70% of normal and grip 60-80%. A wrist that has had its perilunate ligament ring fail does not return to normal, and saying so at the first consultation is easier than saying it here.
Radiographs at 6 months and 1 year, then monitor. Counsel that radiographic post-traumatic arthritis is frequent: Herzberg found 56% even in wrists treated early, and Liechti confirmed it increases with follow-up duration. Say the next part too, because it is the reassuring half and it is well evidenced - radiological osteoarthritis did NOT correlate with reduced wrist function or with patient dissatisfaction, and salvage surgery was needed in only 2.8%. So the counselling line is that the X-ray will very likely look arthritic and that this does not reliably predict how the wrist will feel. Keep salvage options (proximal row carpectomy, four-corner fusion, total wrist fusion) for symptomatic arthritis, not radiographic arthritis.
Outcomes/Prognosis
Functional Outcomes
- Expect 50-70% of normal wrist ROM long-term
- Extension typically most affected (loss of 30-40 degrees)
- Flexion loss of 20-30 degrees
- Radial/ulnar deviation relatively preserved
- Forearm rotation usually normal
- Grip strength typically 60-80% of contralateral side
- Improves with therapy and time
- Plateaus around 12-18 months
- Most patients have some residual pain
- Usually activity-related
- May worsen with arthritis development
- Pain scores improve with time if no arthritis
- Light work: 3-4 months
- Heavy labor: 6 months minimum
- Contact sports: 6-9 months
- Full recovery plateau: 12-18 months
Prognostic Factors
- Early treatment (within 7-14 days)
- Anatomic reduction achieved
- Secure ligament repair
- Greater arc injury (paradoxically - better bone healing)
- Young patient with good bone quality
- Compliant with therapy
- Delayed diagnosis (over 4 weeks)
- Incomplete or malreduced carpus
- Failed ligament repair
- Lesser arc injury (poorer ligament healing)
- Associated nerve injury
- Multiple carpal fractures
- High-energy mechanism
Long-Term Arthritis Risk
- Develops in 50-70% of patients by 5-10 years
- Radiographic arthritis often asymptomatic initially
- Risk factors:
- Residual carpal malalignment
- Articular cartilage damage at injury
- Chronic instability
- Delayed treatment
- Radiocarpal joint most commonly affected
- Midcarpal joint (capitolunate) also common
- May progress to scaphoid nonunion advanced collapse (SNAC) or scapholunate advanced collapse (SLAC) equivalent pattern
- Conservative: NSAIDs, activity modification, splinting
- Injections: Corticosteroid for temporary relief
- Salvage surgery options:
- Proximal row carpectomy (if capitate articular surface intact)
- Four-corner fusion
- Total wrist fusion (last resort for severe symptoms)
- Wrist denervation for pain relief
Guidelines, Registries & Global Practice
Global Epidemiology
Perilunate injuries are rare but consistently under-recognised. They constitute roughly 7% of all carpal traumas in a pooled systematic review (van der Oest 2022), and pure carpal-bone dislocations are far less common than the much more frequent scaphoid fracture in population series: in a Singapore cohort of 149 patients with 162 carpal fractures the scaphoid accounted for 99, and only 10 patients had multiple carpal fractures, of which 4 were perilunate fracture-dislocations (Hey 2011, PMID 21276891). Across the literature the demographic is strikingly uniform worldwide: young men injured by high-energy mechanisms (falls from height, road trauma, sport), reflecting the force required to fail the perilunate ligamentous ring. Hey's cohort matches that picture - 132 of 149 were male and 116 were under 40 - and found high-energy mechanism the only parameter associated with multiple carpal fractures (p=0.009).
- Reported Figure
- ~7% of all carpal traumas
- Evidence Source (PubMed)
- van der Oest 2022 (systematic review)
- Reported Figure
- 25% (41 of 166 injuries)
- Evidence Source (PubMed)
- Herzberg 1993 (7-centre multicentre)
- Reported Figure
- Trans-scaphoid perilunate fracture-dislocation (61%)
- Evidence Source (PubMed)
- Herzberg 1993
- Reported Figure
- ~47% across perilunate injuries
- Evidence Source (PubMed)
- Wickramasinghe 2015 (2 trauma centres)
- Reported Figure
- 15.0% overall; secondary loss of reduction 10.1%
- Evidence Source (PubMed)
- Liechti 2023 (550 patients, meta-analysis)
Guideline & Consensus Landscape
No major society publishes a disease-specific clinical practice guideline dedicated to perilunate/lunate dislocations; management rests on body-of-evidence consensus rather than formal AAOS/NICE guidance. The points of broad international agreement are summarised below.
- Position
- Universally recommended; decompress median nerve early
- Basis / Evidence Level
- Consensus; supported by Wickramasinghe 2015 (evidence level III)
- Position
- Operative (open reduction, ligament repair/fixation) for essentially all injuries; closed treatment alone inadequate
- Basis / Evidence Level
- Consensus; Herzberg 1993, Liechti 2023 (level IV)
- Position
- Surgery within ~7 days gives best outcomes; delay beyond 6 weeks worst
- Basis / Evidence Level
- van der Oest 2022 (systematic review, level IV; 16 included studies, qualitative comparison)
- Position
- Combined dorsal-volar widely taught; dorsal-only and arthroscopic-assisted have lower pooled complication rates in selected cases
- Basis / Evidence Level
- Practice variation; Liechti 2023 (level IV)
- Position
- Radiological osteoarthritis is frequent but often well tolerated; salvage rarely needed (2.8%)
- Basis / Evidence Level
- Liechti 2023; Herzberg 1993 (arthritis 56%)
Registries
There is no dedicated international perilunate-injury registry, and arthroplasty registries (AOANJRR, the UK NJR, the American AJRR) do not capture these soft-tissue/carpal injuries because they are not arthroplasty procedures. The best population-level data therefore come from trauma databases and pooled systematic reviews (Liechti 2023; van der Oest 2022) rather than from a formal registry.
Practice Variation & Service Delivery
Internationally, the dominant modifiable factor is timely recognition and referral rather than choice of implant. Practice variation centres on approach (combined dorsal-volar versus dorsal-only versus arthroscopic-assisted reduction and fixation) and on routine versus selective carpal tunnel release; pooled data favour less invasive techniques where the injury pattern allows (Liechti 2023). High-income trauma systems with 24/7 hand-surgery cover and ready CT access achieve earlier definitive fixation, whereas in many settings inter-hospital transfer from regional centres is the rate-limiting step to surgery within the optimal window. Beyond operative fixation, structured hand-therapy rehabilitation drives final outcome, yet its availability is uneven, with rural and remote regions most affected by limited access.
Mnemonics & Memory Aids
S-C-L-TMayfield Stages
Hook:S-C-L-T: Scapholunate, Capitolunate, Lunotriquetral, Tipped volar - progressive failure pattern
BONE vs LIGAGreater vs Lesser Arc
Hook:Greater arc = Greater bone involvement; Lesser arc = Less bone, more ligament
TRAPClosed Reduction Steps
Hook:TRAP the lunate back in place: Traction, Recreate, Apply pressure, Push and flex
Viva Scenarios
Clinical Decision Scenarios
Practise clinical reasoning and management decisions out loud
“A 35-year-old motorcyclist presents 2 weeks after a fall with persistent wrist pain and weakness. Initial X-rays at another hospital were reported as 'normal'. Current examination shows median nerve paresthesias. You review the original X-rays.”
“A 28-year-old man presents to ED 4 hours after a high-speed motorcycle accident. He has severe wrist pain and reports numbness in his thumb, index, and middle fingers that is worsening. X-rays show a Stage IV lunate dislocation with the lunate tilted into the carpal tunnel.”
“A 32-year-old construction worker fell from scaffolding. X-rays show a perilunate dislocation with a scaphoid waist fracture. The carpus is displaced dorsally with the lunate remaining in the lunate fossa. No median nerve symptoms.”
MCQ Practice Points
Q: In Mayfield Stage III perilunate instability, where is the lunate located?
A: In Stage III (perilunate dislocation), the lunate remains in the lunate fossa of the radius. The capitate and rest of the carpus dislocate dorsally around it. In Stage IV (lunate dislocation), the lunate tips volarly out of the fossa.
Q: What is the "spilled teacup" sign?
A: The spilled teacup sign is seen on lateral X-ray in Stage IV lunate dislocation. Normally, the lunate looks like a cup holding the capitate. When the lunate dislocates volarly and rotates, it appears to have "spilled" out of its normal position - pathognomonic for lunate dislocation.
Q: What is the difference between greater and lesser arc injuries in perilunate dislocations?
A: Lesser arc injuries are pure ligamentous - the injury arc passes through the SL ligament, around the lunate, and through the LT ligament. Greater arc injuries involve fractures - the arc passes through bones (most commonly trans-scaphoid). Greater arc injuries have fractures that need fixation in addition to ligament repair.
Q: What is the urgency of treatment for a Stage IV lunate dislocation with median nerve symptoms?
A: This is a surgical emergency. The volarly dislocated lunate compresses the median nerve in the carpal tunnel. Urgent closed reduction should be attempted immediately (within hours), and definitive surgical treatment with carpal tunnel release is required. Permanent median nerve damage can occur with compression beyond 6-8 hours.
Q: What percentage of perilunate/lunate dislocations are missed on initial presentation?
A: 25% (one quarter) of these injuries are missed initially. This emphasizes the importance of careful examination of the lateral X-ray and maintaining high clinical suspicion. The lunate should articulate with both the radius and the capitate on a normal lateral view.
At a Glance
Perilunate and lunate dislocations represent a spectrum of high-energy carpal injuries following the Mayfield progression of ligamentous disruption. Perilunate dislocation (Mayfield Stage III) maintains the lunate in the lunate fossa while the carpus dislocates dorsally. Lunate dislocation (Mayfield Stage IV) shows volar lunate displacement into the carpal tunnel ("spilled teacup" sign). Trans-scaphoid perilunate is the most common greater arc injury. These injuries are commonly missed on initial X-rays (25%). Treatment is urgent open reduction with ligament repair to prevent median nerve damage and progressive carpal instability.
- Lunate Dislocation
- Stage IV
- Perilunate Dislocation
- Stage III
- Lunate Dislocation
- Displaced volar into carpal tunnel
- Perilunate Dislocation
- Remains in lunate fossa
- Lunate Dislocation
- Partially reduced
- Perilunate Dislocation
- Displaced dorsally
- Lunate Dislocation
- Spilled teacup
- Perilunate Dislocation
- Lunate-capitate malalignment
- Lunate Dislocation
- High (volar lunate directly compresses nerve)
- Perilunate Dislocation
- Lower (acute median neuropathy reported in ~47% across all perilunate injuries, Wickramasinghe 2015)
- Lunate Dislocation
- Mandatory
- Perilunate Dislocation
- Considered if symptoms present
- Lunate Dislocation
- Lower (50-60%)
- Perilunate Dislocation
- Higher (70-80%)
- Greater Arc
- Fractures through bones
- Lesser Arc
- Pure ligamentous disruption
- Greater Arc
- Trans-scaphoid perilunate
- Lesser Arc
- SL and LT ligament tears
- Greater Arc
- Scaphoid, capitate, radial styloid, or triquetrum
- Lesser Arc
- None
- Greater Arc
- Screws for fractures + K-wires
- Lesser Arc
- K-wires only
- Greater Arc
- Bone heals better than ligament
- Lesser Arc
- Ligament healing unpredictable
- Greater Arc
- Less likely to need reconstruction
- Lesser Arc
- May need ligament reconstruction
Mayfield Stages
- Stage I: SL dissociation
- Stage II: Capitolunate dissociation
- Stage III: Perilunate dislocation (lunate in fossa, carpus dorsal)
- Stage IV: Lunate dislocation (lunate volar = spilled teacup)
Key X-ray Findings
- Lateral: Lunate should articulate with radius AND capitate
- PA: Disrupted Gilula's arcs, triangular lunate
- Spilled teacup = Stage IV lunate dislocation
- 25% missed on initial X-ray
Greater vs Lesser Arc
- Lesser arc: Pure ligamentous (SL, LT)
- Greater arc: Fractures through bones (trans-scaphoid most common)
- Greater arc needs fracture fixation + ligament repair
Emergency Management
- Assess median nerve - acute CTS is emergency
- Closed reduction: TRAP (Traction, Recreate, Apply pressure, Push)
- Closed reduction is temporizing only
- All require definitive surgical treatment
Surgical Principles
- Combined volar + dorsal approach preferred
- CTR mandatory (even without acute CTS)
- K-wire fixation: SL, SC, LT
- Greater arc: Screw fixation of fractures + ligament repair
Evidence Base
Carpal Dislocations: Pathomechanics & Progressive Perilunar Instability (Landmark)
- Cadaveric study loading 32 wrists to failure produced 13 perilunate and 2 lunate dislocations via a reproducible mechanism of extension, ulnar deviation and intercarpal supination.
- Established the four sequential stages of perilunar instability (PLI), from scapholunate diastasis (Stage I) to complete lunate dislocation (Stage IV), with progressively greater carpal instability.
- Reduction was achieved by reversing the mechanism (intercarpal pronation, radial deviation, palmar flexion).
Perilunate Dislocations & Fracture-Dislocations: Multicentre Study (Landmark)
- 166 injuries from 7 centres, retrospectively studied; the diagnosis was MISSED INITIALLY IN 41 CASES (25%).
- Displacement was dorsal in 161 (97%) and palmar in only 5 (3%); fracture-dislocations outnumbered pure dislocations 2:1, and dorsal trans-scaphoid perilunate fracture-dislocation was 96% of dorsal fracture-dislocations and 61% of the whole series.
- Outcome analysed in 115 cases at minimum 1 year and mean 6 years 3 months: open injury and delay of treatment adversely affected clinical results, whereas anatomical type mattered less.
- Even in cases treated EARLY the clinical results were satisfactory but post-traumatic arthritis reached 56%.
- Fixing the scaphoid ALONE was not always sufficient - it left residual scapholunate dissociation, lunotriquetral dissociation, ulnar carpal translation or other collapse patterns, so appraise the ligamentous injury as well as the fracture.
Outcomes of Acute Perilunate Injuries: Systematic Review & Meta-Analysis
- Twenty-six studies pooling 550 patients with 553 operatively treated acute injuries (106 pure dislocations, 447 fracture-dislocations) - the largest pooled surgical dataset.
- Overall complication rate 15.0%, driven by secondary loss of reduction (10.1%); reoperation 10.4% and salvage procedures only 2.8%.
- Secondary loss of reduction was HIGHER for pure dislocations than fracture-dislocations (24.2% vs 7.0%, RR 3.5, 95% CI 1.6-7.5) - the pure ligamentous injury is the less stable one after fixation.
- APPROACH AND INVASIVENESS MATTERED: the combined dorsopalmar approach carried more complications than an isolated dorsal approach (17.4% vs 8.4%, RR 0.5, 95% CI 0.2-1.0, NNT 11.2), and open surgery more than arthroscopic (17.4% vs 4.8%, RR 0.3, 95% CI 0.1-0.9, NNT 8.0).
- Radiological osteoarthritis was common and increased significantly with follow-up duration, but did NOT correlate with reduced wrist function or patient dissatisfaction, and salvage surgery was rare.
Perilunate Injury Timing & Treatment Options: Systematic Review
- Perilunate injuries represent approximately 7% of all carpal traumas and are frequently missed; only 16 of 2,056 screened articles met inclusion.
- Timing was stratified as acute (under 7 days), delayed (7-45 days) and chronic (over 45 days). Outcomes are good when surgery is within 7 days, inferior with any delay, and worst beyond 6 weeks.
- Chronic PURE dislocations fare worse than chronic fracture-dislocations - the same direction as Liechti's reduction-loss finding.
- For fracture-dislocations the review suggests CLOSED reduction and internal fixation may give slightly better outcomes than open reduction and internal fixation - a direction that agrees with the modern preference for less invasive fixation.
Acute Median Neuropathy & Carpal Tunnel Release in Perilunate Injuries
- Across 71 patients with perilunate dislocation or fracture-dislocation over 10 years at two trauma centres, acute median neuropathy was diagnosed in 33 (47%).
- NO demographic or injury factor was associated with developing median nerve symptoms - the only significant difference between the dislocation and fracture-dislocation groups was younger age with fracture-dislocation.
- Carpal tunnel release at the initial operation was related to the presence of median nerve symptoms AND to which trauma centre treated the patient - so institutional habit, not just the neurology, determined who was decompressed.