- Discussion: 
- screw is threaded at both ends and can be countersunk beneath articular
surface, obviating the need for removal after frx has healed;
- it is designed to achieve compression by use of a differential thread-pitch
between its proximal & distal ends, and it has guiding jig that
maintains reduction & interfragmentary compression during insertion;
-
disadvantages:
- interfragmentary compressive forces generated by Herbert screw are less than
those associated with conventional screws;
- most of the interfragmentary compression obtained results from the
Herbert screw jig and not the screw itself;
-
indications for surgery:
- main indication is an
unstable scaphoid frx as seen on
x-ray or CT;
- displacment > 1 mm;
- radiolunate angle > 15 degrees;
- scapholunate > 60 degrees;
- indicated for patients w/ delayed unions or
non unions of
scaphoid waist;
- Anterior Approach: 
- Partial Removal of Distal Trapezium:
- Frx Reduction:
- frx is carefully reduced & held by passing K wire across bone in such
way that it will not interfere w/ placement of jig and screw.
- alternatively, the cannulated Herbert screw can be used which does not require
use of the jig;
- the K wire holds the reduction and serves as a guide for the screw;
- w/ comminuted frx, loose fragments are removed and sufficient bone graft is
inserted to provide stability under compression w/o deformity;
- 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 shaped to fill the defect;
- Jig Application: (optional)
- drill guide is placed across the distal pole, and the blade tip is placed
across the proximal pole;
- wherever possible, jig should be applied in such a way that screw will
be perpendicular to fracture;
- if obliquity of frx line makes this impossible, supplementary K wire fixation
should be used to prevent shearing displacement under compression;
- if there is difficulty apply the jig, consider removing a small portion
of the trapezium;
- the jig must be placed more dorsal than expected inorder to avoid creating a
humpback deformity;
- frx site is compressed by jig prior to screw placement;
- as jig is compressed ensure that there is not excessive volar compression which
will cause a humpback deformity;
- measure screw size, off of calibrated guide;
- insert pilot drill for trailing edge of screw;
- long drill is inserted for leading end of screw;
- tap for leading thread (trailing end is self tapping);
- insert screw thru jig;
- Final Radiographic Appearance:
- Post Op Care:
- even w/ Herbert screw fixation many recommend that immobilization be continued
in short thumb-spica cast until there is evidence of frx union;
Management of the Fractured Scaphoid Using a New Bone Screw.
TJ Herbert and WE Fisher.
JBJS Vol 66-B, No 1, Jan 1984.
Treatment of scaphoid nonunion by radical curettage, trapezoidal
iliac crest bone graft, and internal fixation with a Herbert screw.
The Herbert screw for scaphoid fractures. A multicentre study.
Technical factors related to Herbert screw fixation.
Two modifications for insertion of the Herbert screw in the fractured scaphoid.
Internal fixation of scaphoid injuries using the Herbert screw through a
dorsal approach.
Problem Disorders of the Wrist--Symposium: Use of the Herbert Bone
Screw in Surgery of the Wrist.
The Herbert screw for scaphoid fractures. A multicentre study.
