Wrist Instability

Etiology

Acute Ligamentous Instability

• Trauma
• Indirect loading injury

Acute Bony Instability

• Fractures

Chronic Instability

• Repetitive microtrauma 
• Post-traumatic sequela (distal radius fracture)

Systemic Illness

• Avascular necrosis of the scaphoid
• Rheumatoid arthritis

Neurological

• Usually through the development of neurogenic arthropathies, i.e., Charcot-like joints
• Syringomyelia[4]

Congenital Instability

• Madelung deformity causes misalignment of the forearm (radius, ulna) and carpal bones, predisposing to progressive arthrosis and instability.[5]

Epidemiology

• A study by O'Brien revealed that there was a 44 percent cumulative rate of carpal instability during the second year after injury.[6]
• Malunion or growth arrest were the causes of secondary distal radio-ulnar joint (DRUJ) instability in 22% of cases in the J K Andersson study.[7]
• J B Tang observed an incidence of 30.6% after the distal radius fracture.[8]
• Scapholunate angles were found to be irregular in 39% of patients at presentation and 35% of patients after treatment in the distal radius fractures.[9]
• The incidence rates of distal radio-ulnar instability following the distal radius fractures are reported to be between 10% and 19%.[10]

Pathophysiology

Mechanism

Carpal Instability Dissociative (CID)

Instability between bones inside a single carpal row is termed as CID. It may involve either the proximal or distal carpal rows, with the former being more common. It is classified into two types. 

1. Scapholunate (SL):
   • Most common CID instability pattern
   • The scapholunate ligamentous complex and dorsal intercarpal ligaments stabilize this joint from distraction, torsion, and translation.
   • Wrist extension, ulnar deviation, and carpal supination are the most common mechanisms of injury.
   • Scapholunate dissociation leads to the scaphoid flexing palmarly and the lunate flexing dorsally.
   • The main causes of SL instability are SL dissociation which may be an isolated or combined ligamentous injury or a displaced scaphoid fracture.
   • Manifested radiologically as dorsal intercalated segment instability (DISI)[11]
2. Luno-triquetral (LT):
   • Lunotriquetral ligament, radio-lunate ligaments (both volarly and dorsally), and dorsal intercarpal ligaments play a key role in this joint stability.
   • However, LT ligament disruption is the main reason for this instability.
   • The radiological manifestation is as a Volar intercalated segment instability (VISI) pattern.[12]
   • Wrist hyperextension or extension, as well as radial deviation, may cause LT ligament injury.

Carpal Instability Nondissociative (CIND)

CIND does not have a specific distinction between proximal and distal carpal rows. Instead, it involves the whole carpal row, expressed at either the radiocarpal joint, the mid-carpal joint, or both. The pattern and anatomy are not well understood, with no specific classification or treatment.

It consists of two types:

1. CIND-VISI
   • The three bones of the proximal carpal row rotate from flexion to extension when a typical wrist deviates from a radial-deviated to ulnar-deviated posture.
   • This motion is maintained by extrinsic ligaments (triquetral-hamate-capitate ligament, dorsal radio-triquetral, and the anterolateral scaphotrapezial ligament) and intrinsic ligaments (ulno-lunate and lunotriquetral).
   • Flexor carpi ulnaris and extensor carpi ulnaris play their role in moving the proximal row from flexion to extension.
   • Palmar CIND develops when these underlying structures fail due to rupture, dispersion, and increased elasticity.
   • The entire proximal row remains in flexion throughout the movement until the triquetral-hamate joint engages and the proximal row extends with a clunk.[13]
2. CIND-DISI
   • Attenuation of the Dorsal intercarpal ligament, long radio-lunate, radioscaphocapitate ligament, and Scapholunate ligament (Intrinsic) results in dorsal subluxation of the capitate.
   • The dorsal subluxation occurs with the Ulnar deviation of the wrist.[14]

Carpal Instability Complex (CIC)

There are combined patterns of injury between CID and CIND. There is damage or laxity to both volar and dorsal ligaments. The proximal row clunks into extension with ulnar deviation just like VISI-CIND. Furthermore, extremes of ulnar variance induce dorsal capitate subluxation, which is similar to dorsal CIND.

Adaptive Carpus Instability

The carpal ligaments are not usually broken or attenuated, but the dorsal tilt of the malunited distal radius and compensatory dinner fork extension of the proximal row reduce the distances between their origins and insertions. Therefore, Soft ligaments are unable to prevent capitate dorsal translation and distal carpal row.[15]

Perilunate Dislocation

Peri-lunate dislocations are caused by damage to the surrounding balancing structures, such as fractures and articulation or ligament disturbances.

• Intrinsic: scapholunate and lunotriquetral ligaments
• Extrinsic ligaments (palmar): e.g., radio-lunotriquetral, radio-scapholunate, and ulna-lunate are the main stabilizing structures.

The lunate retains its articulated position with the distal radius while the surrounding carpal bones dislocate dorsally. Alternatively, the lunate can dislocate in the volar direction into what is known as the Poirier room, though this is uncommon.[16]

Distal Radial-ulnar Joint (DRUJ) Instability

The volar/dorsal radioulnar ligaments and triangular fibrocartilage complex (TFCC) provide stability to the distal radioulnar joint. Painful pronation and supination following wrist trauma along with positive piano sign indicate distal radio-ulnar joint instability.[17]

History and Physical

History

Generally involves acute trauma, and it is important to ask about the mechanisms of injury. It is typically a fall onto an outstretched hand (FOOSH) injury, with the wrist being in extension or twisting with ulnar deviation. Some common complaints are listed below.

• Painful clunking
• Swelling and or deformity
• Pain in the push-up position
• Weakness in grip
• A sensation of the wrist giving-way
• Paresthesia, along with the distribution of median nerve

Examination

• Snuffbox tenderness
  • would indicate a possible scaphoid fracture
• Dorsal intercalated segment instability (DISI) tests
  • Pain with extreme extension and radial deviation
  • Dorsal wrist pain with loading
  • Tenderness distal to Lister tubercle (scapholunate disruption)
  • Watson Test:
    • Pressure on the volar part of the scaphoid subluxes the scaphoid dorsally out of the scaphoid fossa of the distal radius while deviating from ulnar to radial, and a clunk is sensed as pressure is released when the scaphoid decreases back over the dorsal rim of the radius (DISI).
• Volar intercalated segment instability (VISI) tests
  • LT Shuck test (ballottement test):
    • The lunate is balanced, and the wrist is then taken by radial and ulnar deviation, both active and inactive. If there is discomfort or clicking at the lunotriquetral joint, the test is positive.
  • Lunotriquetral compression test:
    • During radioulnar deviation, the triquetrum is displaced ulnarly, causing discomfort.
• Carpal instability nondissociative (CIND) tests
  • The sudden shift of proximal row into extension with ulnar deviation of the wrist.
• Distal radioulnar joint instability
  • Painful compression of ulna against radius
  • Piano Key Test:
    • The piano-key examination includes pronating the hand and depressing the distal ulna from dorsal to volar. As compared to the contralateral wrist, a favorable effect is characterized by painful laxity of the affected wrist (DRUJ)
• Generalized ligamentous laxity may be present.
• Positive Tinel sign may be elicited if the median nerve is compressed.

Evaluation

Bloods

• Routine labs as a baseline
• Rheumatoid factor and or other connective tissue markers
• CRP and WC to look for features of chronic inflammation or infection

Imaging

• The following radiograph views are recommended
  • Anterior-posterior (AP)
  • Lateral
  • Clenched fist
  • Scaphoid
  • Radial and Ulnar deviation
  • Flexion and Extension
• Specific findings in radiographs that correspond to a specific type of instability
  • Dorsal intercalated segment instability (DISI)
    • Terry Thomas Sign: Increased distance between the scaphoid and lunate, usually >3mm
    • Cortical Ring Sign: Scaphoid rotation/mal-alignment
    • Scaphoid fracture-dislocation
    • Scaphoid shortening
    • Scaphoid humpback deformity
    • Scapholunate angle >70 degrees
    • Capito-lunate angle >20 degrees
  • Volar intercalated segment instability (VISI)
    • Scapholunate angle  < 30 degrees
    • Capito-lunate angle > 15 degrees
    • Break-in Gilula's arc
    • Lunotriquetral overlap
  • Peri-Lunate Dislocation
    • Break-in Gilula's arc
    • The triangular appearance of lunate
    • Slipped Tea Cup sign
  • Distal radio-ulnar joint Instability
    • Widening of the DRUJ
    • Dorsal displacement of ulna
  • Adaptive instability
    • Old fracture malunion of distal radius
    • Dorsal angulation > 30 degrees

In addition to radiographs, we can also perform computed tomography (CT), and magnetic resonance imaging (MRI) scans. These are helpful in particular instances and are divided below,

CT

• Chronic DRUJ
• Fracture dislocation
• Complex fractures
• Misalignments
• Carpal non-unions

MRI

• Undiagnosed ligamentous injury
• TFCC injuries
• Suspected fracture-dislocation

Besides imaging, arthroscopy is the last investigation available for wrist instability. It is the most invasive of investigations listed, but it is considered to be the gold standard for diagnosing ligamentous injuries.

Treatment / Management

Treatment

Dorsal Intercalated Segment Instability (DISI)

Nonoperative

• NSAIDs +- Immobilization is recommended for undisplaced ligamentous injury following a traumatic event.
• Chronic asymptomatic injuries without arthrosis are usually treated conservatively.
• Patient education, splinting, anti-inflammatory drugs, and brief courses of hand therapy should all be part of the treatment plan.

Soft Tissue Reconstruction

• For refractory cases, surgical management may be attempted, but outcomes are not predictable.
• Scapholunate ligament Repair: Scapholunate ligament repair is done on acute injuries without carpal malalignment. Recent studies have shown that the dorsal ligament is all that is necessary to maintain carpal alignment in the absence of radiographic evidence of the failure of the secondary stabilizers of the scaphoid.[18]
• Plication of Ligaments:
  • Suturing the volar radioscaphocapitate ligament to the long radiolunate ligament and closing down the space of Poirier. sixteen out of eighteen patients showed decrease pain at rest and activity.[19]
• Bruneli & Brumeli procedure:
  • Flexor carpi radialis is used to connect the lunate and scaphoid. Flexor carpi radialis tenodesis through the scaphoid and protected with dorsal wrist ligaments has shown encouraging results in a modified Brunelli technique.[20] The wrist is splinted and immobilized following this procedure.
• Plication of Radioscaphocapitate ligament with radiolunate ligament.
• Four bone ligamentous Repair:
  • Double-level tenodesis by using a slip of the extensor carpi radialis brevis. For the surgical treatment of chronic post-traumatic scapholunate instability, combining ECRB ligamentoplasty with dorsal capsulodesis is a safe alternative. 16 patients had outstanding results, eight patients had decent results, three patients had average results, and five patients had mediocre results, according to the Mayo wrist scoring in Papadogeogou's study.[21]
(B2)

Fixed Deformities

Limited Intercarpal Fusion

• Patients with a limited wrist fusion can experience some pain relief while maintaining a functional range of motion.
• A total wrist fusion is not always necessary, so a limited wrist arthrodesis is a viable option.[22]

Triscaphe Arthrodesis

• In localized degenerative arthritis, limited wrist arthrodesis of the joints between the scaphoid, trapezium, and trapezoid is recommended.
• The wrist retains about 80% of its flexion-extension and 66 percent of its radial and ulnar deviation after the three-bone unit is fused.[23]
• Another comparison study showed that the dorsal capsulodesis group performed better (p 0.05) than the triscaphe arthrodesis group in grip strength, range of motion, practical outcome (Krimmer Score), length of the procedure, and hospitalization.[24]

Four Corner Arthrodesis

• Capitolunate-triquetrohamate and triquetrohamate arthrodesis is performed in severe cases.
• When compared to conventional fixation techniques, the rate of significant problems (nonunion or impingement) was much higher with circular plate fixation (48%) than with traditional fixation techniques (6 percent ).
• Grip pressure and arc of motion all decreased by around 30% and 52 percent, respectively, during the plate operation.[25] 
• A retrospective study reveals high union rates are achieved using four-corner fusion with a polyether-ether-ketone locking, dorsal circular disc.[26]
(B2)

Excisional Arthroplasty

• After restricted arthrodesis, persistent pain, especially in hard labor, is common but can be greatly alleviated by simultaneous wrist denervation.[27] 

Radiolunate Fusion

• Midcarpal fusion, although useful in preventing clunking, is linked to changes in the so-called "dart-throwing" motion and is therefore not advised.
• Radiolunate fusion, on the other hand, tends to be a less morbid choice, removing the painful clunking while maintaining a good range of dart-throwing motion [28]
• In a small group of 5 patients who experienced radiolunate arthrodesis, Halikis et al. recorded exceptional pain relief.[29]

Wrist Arthrodesis

• Remove the articular cartilage from the margins of the radiocarpal and intercarpal joints.
• Decorate the third carpometacarpal joint, lunate, capitate, and dorsal fourth of scaphoid.
• Bone grafts from the distal radius or iliac crest may be harvested at this time and inserted into the fusion zone's holes.
• Autograft may be replaced by a cancellous allograft.
• Wrist arthrodesis can only be used in patients who have failed to respond to other treatments, the average satisfaction rating is greater than 75%, and grip power is between 75% and 90%.[30]

VISI

Conservative Management

• A wrist brace can be placed in neutral and ulnar deviation.
• NSAID and splinting is the primary treatment option for acute ligamentous injuries.
• Isometric strengthening exercise of flexor carpi ulnaris and extensor carpi ulnaris is done. 
• Nonsurgical treatment included a pisiform boost patch, nonsteroidal anti-inflammatory medications, steroid injections, and a controlled rehabilitation regimen. 
• It's best to use static orthotics with caution.
• Bracing can help reduce inflammation in an acutely inflamed wrist, but too much reliance can be harmful to proprioceptive feedback.[31][32]

Capsulorraphy:

• Arthroscopic thermal capsulorrhaphy, but chondrolysis is limiting its use.
• The mean DASH score improved from 38 pre-operatively to 17 at the final follow-up, indicating functional progress.
• Our preliminary findings indicate that thermal capsulorrhaphy is beneficial in alleviating the symptoms of palmar instability[33]

Triquetrohamate-capitate Ligament Advancement

• Triquetrohamate-capitate ligament is advanced on the capitate through the bony trough. 
• In three of five wrists, distal advancement of the ulnar arm of the arcuate ligament paired with a dorsal capsulodesis restored flexibility[34]
(B2)

Palmocapsular Reefing

• The space of Poirier is closed after palmar ligament reefing.

Reefing of Dorsal Mid-carpal Ligament

• This technique is used in mid-carpal instability.
• The dorsal radiocarpal ligament is one of the midcarpal joint's main stabilizers, and reefing has been shown to have enough intraoperative stabilization to remove positive midcarpal change test results.
• The dorsal radiocarpal ligament, which runs from the ulnar third of the radius to the dorsal portion of the triquetrum, is defined.
• A 3-cm incision in the dorsal wrist capsule is made to separate the ligament transversely.
• To correct the VISI orientation of the wrist, the distal capsular flap is pulled proximally[35]

Four Corner Arthrodesis

• Carpal bones are fused, but the dart thrower mechanism is disturbed.
• The capitolunate, capitohamate, triquetrohamate, and lunotriquetral joints' articular surfaces are devoid of articular cartilage and secured with staples or K-wires.
• In a consecutive sequence, compare the long-term outcomes of proximal row carpectomy (PRC) and 4-corner arthrodesis (FCA).
• Both forms of surgery are successful at long-term follow-ups.
• Proximal row carpectomy seems to improve wrist movement slightly, thereby reducing surgical risks and eliminating the need for hardware replacement.[36]
(B2)

Radiolunate Fusion

• This prevents dart-throwing mechanism and most beneficial in the management of carpal instability. 
• Radiolunate fusion with a cancellous bone graft from the radius is used to cope with the complicated surgical demands of posttraumatic carpal distortion and resolve the higher frequency of nonunion rate.
• In certain planes of movement, the range of wrist motion improved, surpassing 50% of the contralateral side's usual values, while the overall arc of flexion-extension surpassed 90 degrees.
• Grip intensity increased by 280 percent from its previous level, surpassing 50 percent of the contralateral side.[37]
(B3)

Perilunate Dislocation

Nonoperative

• Nonoperative management is not indicated.
• Just 27% of the time, closed therapy alone was effective in obtaining and sustaining an anatomic reduction.
• 75 percent of the time, open therapy was effective in achieving anatomic reduction. 
• Adkison proposes open reduction and Kirschner wire fixation of displaced lunate and perilunate dislocations in light of these findings.[38]
(B2)

Reduction & Followed by Fixation

• Emergent closed reduction, followed by fixation and ligament reconstruction, is the ideal treatment of choice, indicated in < 8-week old peri-lunate dislocation.
• Loss of wrist motion and grip strength, as well as chronic pain, are normal despite proper care.
• Radiographic evidence of mid-carpal and radiocarpal arthrosis has been found in medium- and long-term trials.[16]

Proximal Row Carpectomy

• If the injury is > 8 weeks old, proximal row corpectomy is the ideal treatment of choice. 
• Takaaki Shinohara found that after proximal row carpectomy, typical flexion-extension values were 59 percent of those on the unaffected hand. The average grip power on the affected hand was 72 percent, and the average adjusted Mayo wrist score was 71 points.[39] The wrist range of motion and grip power is returned to normal.
• A seriously wounded wrist of untreated stage III and IV permanent perilunate dislocations treated with proximal row carpectomy reduces discomfort and improves work.[40]

Total Wrist Arthrodesis

• The total wrist joint arthrodesis is done in degenerated wrist joint following perilunate dislocation.[41]
(B3)

Adaptive Instability

• Corrective osteotomy is required in malunited distal radius fractures associated with carpal instability due to an imbalance of ligaments. 
• The carpus is prepositioned in a dorsal collapse orientation when the usual palmar inclination of the distal articular surface of the radius is lost, allowing this instability to occur.
• Although the instability is limited to the mid carpus, a corrective osteotomy of the distal radius is the appropriate treatment option.
• Osteotomies relieved preoperative complications and improved function in nine patients.[42] 
• In the mid-carpal malalignment community, the carpal alignment improved significantly, returning to normal levels. There was no connection between age and the time between fracture and osteotomy.
• Distal radial osteotomy is a safe and effective treatment for deformities at the distal end of the radius as well as carpal malalignment.[15]

Distal radio-ulnar joint Instability (DRUJ)

Closed Reduction and Splinting

• For stable DRUJ injuries. 
• Since the functional braces did not cross the elbow or wrist, a complete range of motion, including forearm movement, was possible.
• Therefore, the results of reconstructive surgery are not up to the mark in patients with a flat sigmoid notch and bilateral DRUJ hypermobility.[43]

Reduction & Pinning

• This is required in unstable DRUJ injuries. 
• Anatomical reduction and fixation of fractures of the radius and ulna are imperative to restoring the distal radio-ulnar joint.[44]
• Treatment for complicated injuries includes exploration of the DRUJ, extraction of the interposed tissue, soft tissue reconstruction, and open reduction and internal fixation of the ulnar styloid fracture until the associated damage has been addressed (if present and displaced).
• To prevent developing a lifelong DRUJ disobedience, it is important to recognize and treat an acute DRUJ injury as soon as possible.[45]
(B3)

Arthroscopic/Open Debridement

• If TFCC injuries are not amenable to conservative management, arthroscopic or open debridement is required.
• A retrospective study reveals that the arthroscopic treatment of TFCC lesions results in good functional results.[46]
• In terms of DRUJ re-instability and practical outcome ratings, this systematic study finds that open and arthroscopic TFCC repair provides similar outcomes.[47]
(A1)

Distal Ulna Resection Surgery (DURS)

• If the distal ulnar impaction is associated with DRUJ instability, Wafer osteotomy is performed. 
• Conservative treatment, which consists of fixing the distal radius malunion and stabilizing or shortening the ulna, is the treatment of choice if the DRUJ surfaces are preserved.
• DURS is the treatment of choice when the DRUJ surfaces are injured. This method has a low complication rate, and more than 90% of patients report being satisfied with the outcomes, including pain-free wrists and a functional range of motion.[48]

Differential Diagnosis

A painful wrist with clunking and weakness with or without trauma would have a wide range of differentials. These include the following:

• Painful ganglion
• Carpal fractures
• Stress fractures
• Ulnar impaction syndrome
• Essex-Lopresti Injuries
• Galeazzi fractures
• Kienbock disease (lunate avascular necrosis)
• Tendinitis

Staging

Mayfield Classification for Perilunate Dislocation:

• Stage 1: Scapholunate disruption
• Stage 2: Capitolunate disruption
• Stage 3: Lunotriquetrial disruption
• Stage 4: Circumferential disruption

Geissler Arthroscopic Classification of Scapholunate Ligament Injuries:

• Stage I: Attenuation of ligament
• Stage II: Slight gap
• Stage III: Step off of carpal bones, and probe can be passed through carpal bones
• Stage IV: Incongruent and scope can be passed through carpal bones

Prognosis

The outcomes in volar carpal instability are severe than dorsal instability. A good outcome is expected after reduction and fixation following acute instability. Over a seven-year follow-up period, 83 percent of patients who underwent therapy within three months of a scapholunate ligament tear stayed symptom-free and sustained scapholunate joint reduction.[49] Another research data showed that those treated operatively for acute injuries had lower mortality rates and greater functional outcomes than people treated for chronic injuries.[50]

As compared to ligament repair, lunotriquetral arthrodesis is associated with higher complication and re-operation rates.[51]

Chronic injuries and neglected fracture-dislocations lead to poor outcomes in terms of arthritis, wrist fusion, and proximal carpectomy.

Complications

Perilunate Dislocation

• Median nerve compression
• Compartment syndrome
• Lunate ischemia
• Avascular necrosis of lunate

Radiocarpal Instability

• Acute carpal tunnel syndrome
• Wrist stiffness
• Wrist joint arthritis
• Chronic instability
• Wrist deformities

DISI

• Scaphoid nonunion advanced collapse 
• Scapholunate advanced collapse
• Wrist joint stiffness
• Wrist joint arthritis
• Weak Wrist grip

VISI

• Wrist stiffness
• Loss of dart-throwing mechanism
• Chronic Instability

DRUJ

• Distal radioulnar arthrosis
• Chronic pain at wrist joint
• Painful supination/pronation