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Scaphoid / 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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   - Work Up for Scaphoid Fracture: (w/ discussion)

  - clinical differential diagnosis:
- distal radius frx
- transscaphoid perilunate dislocation:
- scaphoid impaction syndrome

- radiographs and determination of stability (CT scan)
- non diagnostic radiograph  (bone scan)
- tubercle frx
- transverse waist frx
- proximal pole frx
- treatment:
- non-displaced fractures
- casting of scaphoid frx
- percutaneous scaphoid fixation
- surgical treatment of displaced fracture (herbert screw fixation of scaphoid fractures):

- complications:
- nonunion of scaphoid (3.5 mm cannulated screw fixation)
- non union of proximal pole
- bone grafting technique
- avascular necrosis of the scaphoid
- SLAC or SNAC wrist
- degenerative disease of the STT joint:
- Degenerative changes at the scaphotrapezial joint following Herbert screw insertion: a radiographic study comparing patients with scaphoid fracture and primary hand arthritis.

- Discussion:
- surface of scaphoid is largely covered by articular cartilage, & only narrow area of its neck, & even smaller distal portion, are
accessible to blood vessels;
- frxs across scaphoid may destroy blood supply to its proximal part;
- scaphoid represents floor of anatomic snuff box;
- scaphoid spans both carpal rows and therefore has less mobility than other carpals;
- scaphoid is principal bony block to dorsiflexion of hand & wrist & is suscepible to frx during fall on outstretched hand;
- scaphoid (navicular): the most frequently fractured carpal bone (frx occurs in tubercle, waist, or proximal 1/3);

- biomechanics and scaphoid movement:
- scaphoid exerts flexion extension control over lunate and distal carpal row;
- ulnar side of the wrist exerts rotational control and stability;
- as wrist rotates from neutral to ulnar deviation, proxomal row dorsiflexes & x-ray profile of the scaphoid appears longer;
- in radial deviation, proximal carpal row volar flexes & scaphoid appears foreshortened;
- hence, ulnar deviation AP is necessary for visualization of scaphoid;
- because scaphoid crosses both proximal & distal carpal rows, excessive dorsiflexion causes it to be pinned between dorsal lip
of radius & palmar sling of the radial capitate ligament;
- scaphoid flexes with wrist flexion & extends with wrist extension, but it also flexes during radial deviation & extends
w/ ulnar deviation;
- these factors make immobilization of scaphoid fractures difficult;
- w/ scaphoid frx, distal scaphoid tends to flex, & proximal scaphoid extends with the proxmal carpal row;
- because of this, angulation occurs at frx site, which gaps open dorsally & gradually assumes a humpback deformity;

    - mechanism of fracture:
- most injuries to wrist are sustained by a fall on outstretched hand;
- frx occurs w/ wrist is dorsiflexed & radially deviated;
- in this position, proximal pole of schaphoid is held by radius & radioscaphocapitate ligament, while distal pole of bone is
carried dorsally by trapeziocapitate complex;
- radioscaphoid ligament is relaxed by & radial deviation & cannot alleviate tensile stresses accumulating on radiovolar
aspect of scaphoid:
- radioscaphoid ligament:
- inserts onto tuberosity of scphoid & is radial expansion of radiocapitate ligament which courses over palmar concavity
of scaphoid proximal to tuberosity before inserting on palmar aspect of capitate;
- forms a fulcrum over which scaphoid rotates;
    - incidence:
           - 1 out of 100,000 people per year;
- ref: Incidence Estimates and Demographics of Scaphoid Fracture in the U.S. Population

- Pediatric Scaphoid Fracture:
   - forms from enchondral ossification
- forms in males between ages 5-15
- forms in forms in females 4-13 years;
- non operative treatment is usually indicated;
- references:
- Pediatric fractures of the carpal scaphoid: a retrospective clinical and radiological study
- Pediatric scaphoid nonunion


- References for Scaphoid Frx