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Surgical Treatment of Scaphoid Fracture

Scaphoid fractures are commonly seen in the young adult male following a sporting injury or a fall on the outstretched hand. More than half of scaphoid fractures occur in the middle third of the bone, as the trabeculae here are the thinnest and most sparsely distributed. The fractures heal by intramembranous ossification with minimal callus to provide initial stability. Premature wrist loading results in varying degrees of shearing, bending and translational forces and will predictably angulate as volar bone is reabsorbed, yielding a “humpback” of flexion deformity of the scaphoid. An untreated or poorly treated scaphoid fracture is highly likely to progress to malunion or non-union. As the scaphoid is a pivotal bone joining the proximal and distal rows, this can result in significant alteration in the wrist biomechanics and degenerative arthritis. Therefore, timely management of the scaphoid fracture is crucial.

Scaphoid fractures are the second most common injuries in the wrist after distal radius fractures and treatments of the undisplaced and minimally displaced fractures of the scaphoid waist have been a source of debate for a long time. The advantages of conservative management in plaster versus surgical internal fixation have been extensively studied,  with no clear consensus (Bond et al 2001, Buijze et al 2010, Dias et al SWIFFT Trial 2020) other than an agreement that  a surgically fixed scaphoid fracture is likely to return to activity earlier.

The implants for surgical fixation of scaphoid have evolved significantly over the last 3 decades. Development of cannulated screws, which can be threaded over guide wires and inserted under fluoroscopic control, has minimized the soft tissue exposure and  injury following an open fixation.

The Acumed Acutrak Headless Compression screw is a conical cannulated screw with the following features:

1. Minimal soft tissue irritation through Headless Fixation

2. Enhanced fracture fixation and improved pull-out strength through a Fully Threaded Construct using a Cancellous Based Thread Design

3. Enhanced window of compression through a Continuously Variable Screw Pitch

This is a Titanium implant with diameters ranging from 2.5mm-7.0mm; making it a versatile tool for a variety of surgical fixations. The Micro(2.5mm), Mini(3.5mm) and Standard(4.0mm) sizes are most suitable for a scaphoid fracture.

Bond CD, Shin AY, McBride MT, Dao KD. Percutaneous screw fixation or cast immobilization for nondisplaced scaphoid fractures. JBJS. 2001 Apr 1;83(4):483. Buijze GA, Doornberg JN, Ham JS, Ring D, Bhandari M, Poolman RW. Surgical compared with conservative treatment for acute nondisplaced or minimally displaced scaphoid fractures: a systematic review and meta-analysis of randomized controlled trials. JBJS. 2010 Jun 1;92(6):1534-44. Dias JJ, Brealey SD, Fairhurst C, Amirfeyz R, Bhowal B, Blewitt N, Brewster M, Brown D, Choudhary S, Coapes C, Cook L. Surgery versus cast immobilisation for adults with a bicortical fracture of the scaphoid waist (SWIFFT): a pragmatic, multicentre, open-label, randomised superiority trial. The Lancet. 2020 Aug 8;396(10248):390-401.

Readers will also find the following OrthOracle operative techniques of interest:

Scaphoid non-union: Zaidemberg (1-2 Intercompartmental Supraretinacular) Vascularised Bone Graft with Acumed Screw Fixation.

Arthroscopic assisted Scaphoid non-union grafting and fixation using Acutrak screw

Scaphoid non-union: Vascularised graft based on the volar carpal artery

Four Corner carpal Fusion using Medartis plate and scaphoid excision

Radioscapholunate fusion using Medartis plate with distal Scaphoid excision

Read more »

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- Discussion:
- primary internal fixation is treatment of choice for unstable scaphoid frxs;
- frx treated by primary internal fixation, avg time for return to work is 3.7 wks w/ union rate, 97 %;
- this compares very favorably with conservative treatment;
- indications for surgery:
- main indication is an unstable scaphoid frx as seen on x-ray or CT scan;
- displacment > 1 mm;
- radiolunate angle > 15 degrees;
- scapholunate > 60 degrees;
- implants:
- Herbert Screw
- 3.5 mm Cannulated Screw Insertion:
- relative fixation strength: (from Toby, et al (1997));
- volar comminution of the scaphoid is a major risk factor for hardware failure;
- AO screw, Acutrak screw, and the Herbert-Whipple screw have superior reistance to cyclic bending loads compared to the Herbert screw;
- A comparison of fixation screws for the scaphoid during application of cyclical bending loads.
- Anthropometry of the Human Scaphoid
- preoperative considerations:
- note that a dorsal humpback malunion is possible even with surgical fixation, and that even w/ small degrees of malunion will result in a significant loss of wrist extension;
- fracture is exposed using an anterior approach;
- w/ dislocation of the midcarpal joint, an attempt should be made to reduce this by closed manipulation before draping;
- if dislocation is unstable, or if there are signs of median nerve compression, a more extensive exposure is used:
- in complex frx-dislocations, it may be necessary to make dorsal as well as a volar approach to the carpus;
- flexor retinaculum is completely divided and the midcarpal joint approached through the floor of the carpal tunnel;
- outcomes of surgical treatment of scaphoid fracture


- Incision and Exposure:    
- tubercle of scaphoid is palpated distal to lower visible or palpable end of FCR;
- skin incision is centered over scaphoid tubercle and curved distally into thenar base;
- made proximally from tubercle for 3 cm, between tendon of FCR medially & radial artery laterally;
- incision is carried down between tendon of FCR & radial artery;
- radial artery & its palmar branch are on radial side of FCR;
- median nerve & its palmar branch are on ulnar side of the tendon;
- scaphoid is then approached thru separate longitudinal incision in capsule on radial side of FRC tendon;
- some surgeons prefer to longitudinally incise thru the dorsal bed of the FCR sheath;
- w/ acute frx, expect hemarthrosis in both the radiocarpal and the distal scaphoid joints, making the use of a fine sucker essential;
- distal scaphoid is exposed by making a transverse incision at the STT joint;
- alternate incision:
- may be indicate for extreme humpback deformities or radio-scaphoid impingement;
- consider using the interval between the radial artery and first extensor compartment (on the volar side) and the EPL (on the dorsal side);
- key to exposing the scaphoid lies in dorsiflexion of wrist and axial traction on the thumb;
- this will expose the proximal pole of scaphoid, which is site of most cases of nonunion;
- avoid dividing the the radioscaphoid capitate ligament;
- preservation of the radioscaphoid ligament maintains the proximal pole of the scaphoid in a reduced position in the fossa of the distal part of the radius;
- w/ division of the radioscaphoid ligament is divided, the proximal pole may translate in a volar direction, complicating the reduction;

    


- Debridment:
- in cases of non-union use curets or highspeed burr to debride the non union site of fibrous tissue, while taking care not to damage the outer cortical shell;
- alternatively consider using a 3 mm oscillating saw inorder to cut the scaphoid back to bleeding bone;

- Reduction:
- consider using dental picks to manipulate the frx fragments into reduction;
- K wires can be inserted perpendicular to the frx fragments inorder to "joystick" them into  reduction, but this may cause further comminution;
- in cases of scaphoid humback deformity the lunate should be reduced before correcting the scaphoid deformity;
- the lunate should be reduced back to a neutral position by pinning it to the radius;
- note that even a small humpback deformity will leave the patient with restricted dorsiflexion;
- if the reduction is difficult, articular border of the scaphoid with the capitate can be used as a "mold" inorder to realign the fractured scaphoid;


- Guide Wire Insertion:
- the key to proper guide wire insertion is good visualization of the scaphoid;
- insert a freer elevator along the proximal-radial aspect of the scaphoid (into the radial-carpal joint), inorder to allow a lateral view of the scaphoid;
- in many cases, the guide wire will be inserted too volarly and is not directed adequately to the distal-ulnar tip of the scaphoid;
- consider using a rongeur to remove a small portion of the non articulating portion of the trapezium inorder to allow a more dorsal insertion of the guide wire;
A Comparison of 2 Methods for Scaphoid Central Screw Placement From a Volar Approach
- stabilizing guide wire:
- place a guide wire along the radial border of the scaphoid to control rotation;
- once this guide wire is in place, wrist can be ulnarly deviated to better expose the scaphoid body for wire insertion down the central third of proximal pole;
- Trumble, et al (1996), left the second stabilizing K wire in place for 6-8 weeks postop;
- cannulated screw guide wire:
- as pointed out by Trumble, et al (1996), the key to a successful result is placement of the guide wire in the central third of the proximal pole of the scaphoid;
- these authors emphasized that the guide wire needs to be placed in the central third of the proximal scaphoid on both PA, lateral, and oblique radiographs;
- Non-union of the scaphoid. Treatment with cannulated screws compared with treatment with Herbert screws.
- Pronated Oblique View in Assessing Proximal Scaphoid Articular Cannulated Screw Penetration

   

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- Wound Closure:
- when performing a volar approach, radioscaphocapitate ligament and palmar radiolunate-triquetral ligament must be partially or totally divided;
- see ligaments of the wrist;
- if inadequately repaired, the natural tendency of the lunate to extend and the scaphoid to flex under axial compression may lead to a DISI deformity;

- Post Op Care:
- even w/ ORIF many recommend that immobilization be continued in short thumb-spica cast until there is evidence of frx union;
- note that with cannulated screw fixation, average time to union is about 4 months


Dorsal approach to scaphoid nonunion.

Corticocancellous grafting and an AO/ASIF lag screw for nonunion of the scaphoid. A retrospective analysis.

Corrective osteotomy for scaphoid malunion: technique and long-term follow-up evaluation.

The Herbert screw for scaphoid fractures. A multicentre study.

Scaphoid fractures: dorsal versus volar approach.

Operative management of pediatric scaphoid fracture nonunion.

Central screw placement in percutaneous screw scaphoid fixation: a cadaveric comparison of proximal and distal techniques.