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Scapholunate Instability

- Discussion:
- anatomy and ligamentous contraints:
           - ligaments of the wrist
- SL interosseous ligament
- SLD is most common and most significant ligament injury of wrist; (carpal instability);
- risk factors: ulna minus configuation, slope of radial articular surface, and lunotriquetral coalition;

This is a detailed step by step instruction through a Modified Brunelli reconstruction of the scapho-lunate interosseous ligament (SLIL) also know as the 3 ligament tenodesis. 

The operation is performed to restore carpal mechanics following a SLIL injury and often subsequent attrition of the secondary stabilisers leading to a dorsal-intercalated segment instability (DISI). SLIL injuries over 4-6 weeks old are often very difficult to repair primarily and may require reconstruction if symptoms persist. If the wrist remains symptomatic despite appropriate rehabilitation, splintage and analgesia therapy, surgery may be required.

This can be the case in Geissler grade 3 or 4 ligament tears seen arthroscopically and may also be the operation of choice in grade 1 scapho-lunate advanced collapse (SLAC) in conjunction with a radial styloidectomy.

The operation uses a third to a half of the flexor carpi radialis (FCR) tendon which is passed through the scaphoid, across the dorsal lunate and around the dorso-radiocarpal ligament (DRC). This aims to reconstruct the volar secondary stabiliser of the scapho-trapezial-trapizoid ligament (STT), the dorsal limb of the SLIL and tighten the secondary stabiliser of the DRC. The operation is performed as a daycase procedure and the patient is placed in cast for 4-6 weeks following the procedure to start focussed rehabilitation once casting is complete. 

Patients often return to light work at 8 weeks, heavy work at 3 months and continue to strength and improve up to a year post-operation.

Author: Mr Mark Brewster FRCS (Tr & Orth)

Institution: The Royal Orthopaedic Hospital, Birmingham ,UK.

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- spectrum of injury: (increasing severity)
- ref: Association of lesions of the scapholunate interval with arthroscopic grading of scapholunate instability via the geissler classification.
- dynamic scapholunate instability
- no radiographic evidence of malalignment is present (ie dynamic deformity);
- diagnosis is established by dorsal S-L tenderness and positive shift test;
- ref: The Role of the Flexor Carpi Radialis Muscle in Scapholunate Instability 
- rotatory subluxation of scaphoid:
- scapholunate dissociation (SLD):
- SL ligament tear may lead to rotational dislocation of scaphoid allowing proximal pole to displace posteriorly & distal pole
to displace anteriorly;
- scaphoid inherently tends to palmar flex because of its oblique position and the loading applied thru (STT) joint;
- because scaphoid lacks  proximal of ligament, it will rotate around radiocaptitate ligament leading to dorsal rotary
subluxation of the proximal pole;
- dorsal intercalated segment instability: (DISI)
- scapholunate advanced collapse:
- mechanism of injury:
- mechanism is similar is similar to that of scaphoid frx w/ stress loading of extended carpus, except it is usually in ulnar rather
than radial deviation;
- w/ a severe hyperextension injury of the wrist, there is tear of scapholunate interosseous ligament;
- further loading causes tear of (in succession);
- radiocapitate ligaments;
- radiotriquetral ligaments;
- dorsal radiocarpal ligaments;
- lunate follows triquetrium into extension, & DISI deformity results;

- associated injuries:
- simultaneous radial styloid frx is relatively common w/ carpal dislocation;
- always consider non-displaced scaphoid frx;
- diff dx:
- scaphoid impaction syndrome (SIS);
- occult ganglion cyst;
- posterior interosseous nerve neuroma;
- ulnar translocation:
- physiologic scapholunate separation such as lunotriquetral coalition (compare to other hand);
- perilunate dislocation (which has be reduced and splinted)
- references:
- Is this scapholunate joint and its ligament abnormal?
- Wide scapholunate joint space in lunotriquetral coalition: a normal variant?
- Coincident rupture of the scapholunate and lunotriquetral ligaments without perilunate dislocation: pathomechanics and management.

- Radiographic Findings: in Scapholunate Dislocation:
- Traction radiography for the diagnosis of scapholunate ligament tears.

- Exam for Scapholunate Instability

- Non Operative Treatment:
- non operative treatment can only be recommended for dynamic scapholunate instability;
- suggested measures include: activity modification, NSAIDS, and wrist splinting;
- references:
- Chronic asymptomatic contralateral wrist scapholunate dissociation.
- Obvious radiographic scapholunate dissociation: X-ray the other wrist.

- Treatment Options for Acute Tears:

- manipulation & closed pinning:
- may correct a fresh scapholunate dissociation;
- flex & ulnar deviate the wrist to produce lunate reduction & flexion;
- consider retrograde insertion of K wire thru scaphoid and out radial side of wrist, pulling K wire out radially, and then
advancing K wire into ulna;
- be aware that K wire insertion may displace lunate;
- K wire should be inserted into distal cortex of lunate, but midcarpal joint should be left free to absorb small movements;
- scaphoid should be pinned similarly if not perfectly reduced to lunate;
- reduction of scaphoid is achieved w/ thumb pressure dorsally over proximal pole;
- avoid distraction using slow insertion under flouroscopy;
- screw fixation:
- Reduction and Maintenance of Scapholunate Dissociation Using the TwinFix Screw
- The use of temporary screw augmentation for the treatment of scapholunate injuries.
- Chronic scapholunate instability treated with temporary screw fixation.
- Scapholunate Temporary Screw Fixation for the Treatment of Chronic Scapholunate Instability
- Treatment of Scaholunate Instability with Internal Screw fixation

- acute ligament repiar:
- dynamic reconstruction:
- Dynamic Repair of Scapholunate Dissociation With Dorsal Extensor Carpi Radialis Longus Tenodesis
- Brunelli Tenodesis :
- Distal Tunnel Placement Improves Scaphoid Flexion With the Brunelli Tenodesis Procedure for Scapholunate Dissociation

- Treatment Options for Chronic Tears: Capsulodesis:
- dorsal intercarpal ligament capsulodesis:
- this technique does not tether the scaphoid to the distal radius (as does the blatt capsulodesis), the technique may
permit  good closure of the scapholunate gap without restricting wrist motion;
- in the study by Slater, et al (1999), the dorsal intercarpal ligament capsulodesis reduced SLD gap formation down to 1 mm vs
3.7 mm using the blatt dorsal capsulodesis technique;
- technique:
- 5 mm wide flap of dorsal IC ligament (triquetral-trapezoidal) is elevated off trapezoid (left attached to triquetrum);
- scaphoid is taken out of its flexed position (finger on the scaphoid tubercle) and the scapholunate gap is reduced;
- flap is then rotated down, stretched as tightly as possible, and is then attached to the distal pole of the scaphoid (about
3-4 mm proximal to the STT joint);
- Dorsal intercarpal ligament capsulodesis for scapholunate dissociation: biomechanical analysis in a cadaver model.
- blatt dorsal capsulodesis:
- involves creation of a flap of wrist capsule (left attached to the radius) which is inserted onto the dorsal pole of the scaphoid;
- the fact that there remains a tether to the distal radius may infact be a disadvantage of this procedure;
- can be used instead of, or in addition to, the repair of the ligament, and can be performed for chronic dynamic instability as
well as for chronic SLD;
- capsulodesis keeps scaphoid from subluxating in palmar direction and corrects flexed posture of scaphoid;
- disadvantages: fails to correct the diastasis and significantly decreases wrist ROM;
- technique:
- dorsal capsular flap is left attached to radius proximally & is then subsequently inserted in distal part of the scaphoid to
tether distal pole dorsally;
- length of the dorsal capsular flap from the origin at the distal radius to the STT joint;
- references:
            - Capsulodesis in reconstructive hand surgery. Dorsal capsulodesis for the unstable scaphoid and volar capsulodesis following excision of the distal ulna.
- Dynamic scapholunate instability: results of operative treatment with dorsal capsulodesis.
- Treatment of scapholunate dissociation by ligamentous repair and capsulodesis.
- Dorsal intercarpal ligament capsulodesis for chronic, static scapholunate dissociation: Clinical results
- Radiographic evaluation of the modified Brunelli technique versus the Blatt capsulodesis for scapholunate dissociation in a cadaver model.
- Four-bone ligament reconstruction for treatment of chronic complete scapholunate separation.
- Long-term results of dorsal intercarpal ligament capsulodesis for the treatment of chronic scapholunate instability

- STT fusion
- scapholunate fusion:
- mentioned only to be condemned;
- expect non union rates over 90%;
- references:
- Scaphocapitolunate arthrodesis.
- Scaphoid-trapezium-trapezoid fusion in the treatment of chronic scapholunate instability.
- Treatment of scapholunate dissociation. Rotatory subluxation of the scaphoid.
- A comparison of scaphoid-trapezium-trapezoid fusion and four-bone tendon weave for scapholunate dissociation.
- Attempted scapholunate arthrodesis for chronic scapholunate dissociation.
- Treatment of scapholunate dissociation: preferred treatment--STT fusion vs other methods.
- Long-term follow-up of scaphoid-trapezium-trapezoid arthrodesis.
- Evaluation of the biomechanical efficacy of limited intercarpal fusions for the treatment of scapho-lunate dissociation.

- Scapholunate Advanced Collapse (SLAC):
- Proximal Row Carpectomy
- 4 Corner Fusion
- Wrist Fusion
- references
- Fascial implant arthroplasty for treatment of radioscaphoid degenerative disease.
- On resection of the proximal carpal row.
- Proximal row fusion as a solution for radiocarpal arthritis.
- Scaphoid excision and capitolunate arthrodesis for radioscaphoid arthritis.
- Treatment of scapholunate dissociation by ligamentous repair and capsulodesis.
- Radio-scapho-lunate partial wrist arthrodesis following comminuted fractures of the distal radius.

Symposium--Progress in Sports Medicine: Athletic Injuries of the *Wrist.*

Dorsal intercarpal ligament capsulodesis for scapholunate dissociation: biochemical analysis in a cadaver model.

Scapholunate Stabilization With Dynamic Extensor Carpi Radialis Longus Tendon Transfer

Proximal row carpectomy for scapholunate dissociation