- See:
Avascular Necrosis of the Scaphoid
- Discussion:
- these often result from undiagnosed or undertreated
non displaced scaphoid fractures, especially when associated w/
carpal instability;
- even when found as late as 6 mo after the injury, frx of scaphoid, esp at the
waist and
distal location, may go on to heal;
- progressive collapse & deformity usually occur at frx site, leading to subluxation of midcarpal joint and
dorsal rotation of the lunate;
- nature history often leads to late radioscaphoid degenerative changes, followed by pancarpal arthritis (
SLAC);
- in the study by F. Schuind et al (JHS Vol 24-A. No 4 Jul 1999), several negative factors were identified for healing;
- negative factors include use of a dorsal approach (wrist stiffness), and time lapse of more than 5 years from injury;
- the authors raise the question of whether asymptomatic scaphoid non unions should undergo sugery, especially if a proximal pole frx is present;
-
poor prognostic signs:
- there is concern with a capitolunate angle of > 10 deg, almost certain problem when angle is > 20 deg;
-
saggital CT may pick up the deformity;
-
DISI deformity, radiocarpal degenerative changes, and poor scaphoid bone quality are all poor prognostic signs;
- references:
-
The natural history of scaphoid non-union.
-
The natural history of scaphoid non-union. A review of fifty-five cases.
- Exam Findings:
- pts demonstrate marked loss of wrist dorsiflexion, which can be improved if the deformity is corrected;
- Radiographs:
- radiographs (including
CT scan and MRI) allow determination of carpal collapse, scaphoid collapse, bone loss, and
osteonecrosis;
- there is a tendency for the fracture to gap open dorsally;
- ulnar deviation opens gap radially, and extension of waist is not particularly in closing the dorsal gap;
- in some cases, it will be difficult to tell if scaphoid healing has taken place;
- a magnifying glass may reveal some trabeculation across the persistent frx radiolucency;
- if the diagnosis remains in doubt, order a CT scan w/ reformated images;
- note that a humpback scaphoid deformity is often associated w/
DISI
- upto 35% of patients demonstrate a humback deformity and about 40% demonstrate a DISI deformity;
- Nonunion of Proximal Pole:
- Early Surgical Treatment:
- in early cases, it may be possible to restore full length to scaphoid by means of bone grafting & thus correct carpal deformity;
-
debridment:
- it is important that all fibrous tissue be excised and replaced w/ sufficient bone graft to maintain length of scaphoid under compression;
- 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;
- it is important that the dorsal scaphoid cortex is preserved to serve as a tension band;
-
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;
-
cautions:
- when frxed, proximal pole tends to extend w/ lunate, & distal pole tends to flex (may result in dorsal gaping);
-
osteonecrosis: consider need for vascularized bone graft;
-
bone grafting:
-
bone graft harvest techniques:
-
Russe Technique:
- w/ a well alinged non union, bone graft may consist of cancellous chips;
- w/ a malaligned non union which requires reduction, bone graft should be a cortico-cancellous piece that is shaped to fill the defect;
-
fixation methods:
-
Herbert Screw Fixation
-
3.5 mm Cannulated Screw Insertion:
- Late Treatment:
- in late cases, associated soft-tissue contracture prevents complete correction but dorsiflexion usually can be improved by lengthening the scaphoid;
- if secondary radiocarpal arthritis has occurred, limited radial styloidectomy is a useful adjunct to reconstruction;
- it relieves both pain & restriction of movement assoc w/ impingement of the scaphoid on the radius;
- Salvage Procedures:
-
Four Corner Fusion;
-
Proximal Row Carpectomy;
-
Wrist Arthrodesis;
-
limited fusion: (proximal scaphoid pole, lunate, capitate);
- motivation for this form treatment is based on the observation that the proximal pole-distal radius articulation is often spared degenerative changes for the first decade following injury;
- indicated for chronic scaphoid non unions w/ degenerative changes, and DISI deformity (may also be used for
scapholunate dissociation);
- may be relatively contra-indicated w/ very proximal scaphoid nonunions;
- longitudinal incision is made over the ulnar aspect of the 4th compartment;
- extensor retinaculum is incised in a step cut pattern;
- longitudinal incision is made in the wrist capsule extending to the mid carpal row;
- the distal fragment is then carefull excised;
- cartilagenous surfaces between the proximal pole, lunate, and capitate are removed;
- DISI deformity of the lunate should be corrected;
- percutaneous pins are inserted: captiolunate, scapholunate, and scaphocapitate;
- cancellous bone graft is applied between the carpi;
- references:
- Limited Arthrodesis for Scaphoid Nonunion; SF Viegas MD. Journal of Hand Surgery. 19-A. 1994. 127-133;
-
Scaphocapitolunate arthrodesis.
-
STT fusion:
- is usually combined w/ a bone graft can be offered;
Dorsal approach to scaphoid nonunion.
Corticocancellous grafting & AO/ASIF lag screw for nonunion of the scaphoid. A retrospective analysis.
Percutaneous pinning of symptomatic scaphoid nonunions.
Scapholunate gap with scaphoid nonunion.
Recalcitrant non-union of the scaphoid treated with a vascularized bone graft based on the ulnar artery.
Compression-Staple Fixation for Fractures, Non-Unions, and Delayed Unions of the Carpal Scaphoid.
Treatment of scaphoid nonunion by radical curettage, trapezoidal iliac crest bone graft, and internal fixation with a Herbert screw.
Treatment of ununited fractures of the scaphoid by iliac bone grafts and Kirschner-wire fixation.
Limited triscaphoid intercarpal arthrodesis for rotatory subluxation of the scaphoid.
Prognostic factors in the treatment of carpal scaphoid non unions. F. Schuind MD et al. J. Hand Surgery. Vol 24-A. No 4. Jul 1999. p 762.
Use of the 1,2 intercompartmental supraretinacular artery as a vascularized pedicle bone graft for difficult scaphoid nonunion
Operative management of pediatric scaphoid fracture nonunion.
Resection of the distal pole of the scaphoid for scaphoid nonunion with radioscaphoid and intercarpal arthritis.
Preliminary lunate reduction and pinning facilitates restoration of carpal ht when treating perilunate dislocation, scaphoid frx and nonunion, and SLD.
Thumb metacarpal vascularized bone graft in long-standing scaphoid nonunion—a useful graft via dorsal or palmar approach:A cohort study of 24 patients.
Bone grafting the scaphoid nonunion: a systematic review of 147 publications including 5,246 cases of scaphoid nonunion.
Resection of the Scaphoid Distal Pole for Symptomatic Scaphoid Nonunion After Failed Previous Surgical Treatment.
