evidence-based practice for scaphoid fractures and non-union

1. Scaphoid
fractures
- a review
Vaikunthan Rajaratnam

2. Demographics
• most common wrist fracture
• 60% of all carpus fractures
• 22 to 141 per 100,000 person-years
• common in younger and males
• Early diagnosis crucial
• Appropriate treatment

3. Anatomy
• largest bone in the proximal row
• tie-rod linking the proximal and distal carpal rows
• 5 articulations –
1. distal part of the radius proximally,
2. the lunate on the proximal ulnar side,
3. the capitate via the large ulnar concavity,
and
4. dorsoulnarly with the trapezoid and
5. radiovolarly with the trapezium

4. Blood supply
• 80%, is cartilage providing few
entrances for vascularity
• majority of vessels enters the dorsal
ridge from the radial artery
• Predominant retrograde blood supply
• the proximal pole is at higher risk for
osteonecrosis and non union
Arrow 1 illustrates the retrograde blood supply entering the
distal dorsal ridge of the scaphoid leading to hypovascularity of
the proximal pole. Arrow 2 represents the volar blood supply to
the distal pole of the scaphoid. (: Gelberman RH, Menon J. The
vascularity of the scaphoid bone. J Hand Surg Am. 1980
Sep;5[5]:508-13)

5. Biomechanics
• intercalated proximal carpal row
• strong scapholunate ligament limits
scapholunate motion
• stability dependent on intact scaphoid
• unstable fracture- the lunate to extend
with the triquetrum, proximal pole of
the scaphoid rotates dorsally with the
lunate, the distal pole remains flexed

6. Kinematics
• Most non-union are symptomatic
• scaphoid humpback deformity
• dorsal intercalated segment
instability (DISI) deformities
• Nonunion - carpal collapse
• Osteoarthritis - scaphoid non-union
advanced collapse (SNAC)
Black triangles indicate the apex of the dorsal scaphoid ridge. (A) The
volar type of scaphoid nonunion, as seen from the lateral view, showing
the direction of fracture displacement (solid arrows) and the inferred
contact area between the distal fragment of the scaphoid and the radius
(open arrows). (B) The dorsal type of scaphoid nonunion, as seen from
the lateral view, showing the direction of fracture displacement (solid
arrow) and the inferred contact area between the distal fragment of the
scaphoid and the radius (open arrows).
J Hand Surg Am 2000;25:520–528.

7. Kinematics
(A) Force of the scaphoid rotating into flexion and pronation counters the force of the triquetrum rotating into extension and
supination. With distal fractures, the link to the proximal row is broken at the fracture site. (B) The proximal fragment of the
scaphoid and lunate, and the triquetrum extend and supinate. (C) The capitate and the distal fragment translate in the dorsal
direction due to the effect of the extension of the lunate. (D) With proximal fractures, the link to the proximal row survives
and the proximal row remains stable. ( J Hand Surg Am 2005;30:1136–1144.)

8. Classification

9. Investigations
• Three-dimensional CT
• Intra-operative bleeding -
indicator of vascularity
proximal fragment
• MRI scan T1-weighted
image with use of
gadolinium.
( a ) MRI with signal loss in T1 imaging ( b ) MRI with
hyperenhancement by use of gadolinium in T2 fat saturated imaging
as a sign of compromised blood supply

10. Diagnosis
Early MRI
cost-effective
reduce unnecessary
immobilization
assessment of the vascularity
of the proximal pole
identification of other
ligamentous and
Soft tissue injuries
MRI and CT had high sensitivities and specificities
even with multiple views, X-rays miss fractures in 27% of cases

11. Nonoperative
Compared with
Operative
un/minimally
displaced
no difference in union rates and
an increased rate of complications with
operative treatment
Non operative methods - no significant
differences in union rate, pain, grip
strength, time to union, or osteonecrosis
for varied methods of casting methods

12. Operative Treatment
• Indications
• fracture instability,
• displacement,
• angulation,
• malrotation, and
• fracture of the proximal pole
Precise screw placement is critical
Complication rates - 29% with operative intervention
• non-union,
• osteonecrosis,
• posttraumatic arthritis, and
• flexor and extensor tendon ruptures

13. The Evidence
Colles cast for up to 12 weeks.
The wrist should not be in flexion.
There is no advantage of an above
elbow cast over a below elbow cast.
Operative treatment for scaphoid
does not provide a higher union rate
in undisplaced fractures, but may do
in displaced fracture.
Open approach seems to be
superior to percutaneous fixation.

14. Scaphoid Non Unions

15. Incidence
• Frequency - 12.4 of 100,000
fractures per year
• non-union rate approximately 10%
• abnormal wrist kinematics
• carpal collapse
• subsequent degenerative arthritis

18. High Union Rates
• risk of reporting bias
• assessments of radiographic union after bone grafting
• definitions of union and delayed union
• Failure of union post bone graft is a diagnosis of exclusion.
• partial unions usually consolidate with time
• CT scans failed to describe how much bridging needed for union classification
“Fewer non-unions will be missed on CT or MRI scans, which are free of parallax, but image distortion due to a
cannulated screw or other implant within the scaphoid may cause uncertainty”

19. Scaphoid Non-unions risk factors
• Delayed diagnosis
• Inadequate initial management
• Proximal fracture location
• Avascularity of proximal pole
• Fracture instability
• Delay in Surgery
• Osteonecrosis, and associated carpal instability with acute scaphoid
fracture can lead to nonunion of the scaphoid waist or the proximal pole.
• Nonunion can exist with or without osteonecrosis of the proximal
fragment.
Herbert screw fixation for scaphoid nonunions. An analysis of factors influencing outcome.Inoue G, Shionoya K, Kuwahata Y
Clin Orthop Relat Res. 1997 Oct; (343):99-106.

20. Treatment of Scaphoid Non-union
• Healing of proximal pole scaphoid non-union can be achieved with
stable internal fixation and bone grafting.1
• The rate of healing correlates directly with the vascularity of the
proximal pole.2
• Unfortunately, fibrous union and persistent nonunion tend to develop
when osteonecrosis of the proximal pole is present.
• Such conditions are often refractory to traditional bone grafting
methods, even when augmented with internal fixation.
• Theoretically, the use of pedicled VBGs, which help revascularize
ischemic bone, should improve the union rate and time to union.3
1. Inoue G, Shionoya K: Herbert screw fixation by limited access for acute fractures of the scaphoid. J Bone Joint Surg Br 1997;79:418-421.
2. Green DP: The effect of avascular necrosis on Russe bone grafting for scaphoid nonunion. J Hand Surg [Am] 1985;10:597-605.
3. Shin AY, Bishop AT: Pedicled vascularized bone grafts for disorders of the carpus: Scaphoid nonunion and Kienbock’s disease. J Am Acad Orthop
Surg 2002;10:210-216.

21. Treatment Goals
• achieving union
• correcting deformity
• restoring the carpal alignment
• prevent degeneration of wrist joint
• Stability and blood supply
Principles of surgical intervention
• resecting the pseudarthrosis until cancellous bone
• putting in a bone graft
• restoring the original shape and length
• rigid stabilization

22. Non- vascularized
Bone Graft
• Fibrous non-union, carpal alignment is
preserved
• resecting the pseudarthrosis
• cancellous bone graft - distal
radius/olecranon
• screw fixation a palmar approach
or dorsal approach for the proximal
third
• longstanding “hump backed” deformity
• initially correct the DISI deformity
• restoration of the length
• large tri cortical bone graft
• Headless screw
• failed surgery
• screw removal
• revision larger bone graft and
• fixation with an external plate

23. Vascularised bone graft
reserved for the true avascular
proximal fragment
• proximal pole non-union
• dorsal approach
• pedicle 1/2 supraretinacular
intercompartmental artery-
Zaidemberg
• fixation - mini screw
• Alternative- pedicle bone graft
from the palmar surface of the
distal radius
• Fixation - a headless bone
screw or two K-wire
• free iliac crest or the medial
femoral condyle
• provide blood supply
• structural support
• deformity correction

24. Vascularised bone grafting
• Zaidemberg1 first described a pedicled
vascularised bone graft, which relies on
the 1,2 intercompartmental
supraretinacular artery (1,2 ICSRA).
• This artery travels in a distal to proximal
direction along the retinaculum between
the tendons of the first and second dorsal
compartment.
• The 2,3 ICSRA may also be used in select
patients in whom the 1,2 ICSRA is small
or absent.
1. Zaidemberg C, Siebert JW, Angrigiani C: A new vascularized bone graft for scaphoid nonunion. J Hand Surg [Am] 1991;16:474-478.

25. Outcomes
• Non vascularised
• overall union rate as seen on x-ray was 71 %, absence of AVN at between 90
and 100 %, when AVN is present to less than 70 %
• Vascularised
• AVN - 80–100 % union rate
• free vascularized bone grafts - medial femoral condyle - 80 and 90 %

26. 30/M, Construction worker
• 4weeks old injury
• Right hand hit by trolley
• Saw TCM first
• Initially placed in scaphoid cast
• XR - scaphoid proximal pole #
• CT - sclerosis and cystic changes
c/w old fracture
• Surgical fixation of right scaphoid
with vascularised bone graft

31. KTPH Hand Surgery Experience
• Case series of 59 Patients underwent ORIF of scaphoid fracture
• 29 patients (49.2%) underwent concomitant bone grafting
• 7 (24.1%) Artificial bone grafts
• 22 (75.9%) Autologous bone grafting
• Autologous bone grafting
• 17 (77.3%) - non-vascularized bone grafts obtained from the radius
• 4 (18.2%) - pedicled bone grafts from the radius
• 1 (3.4%) - free vascularized bone grafting from the medial femoral condyle.
• Vascularized bone grafts if MRI showed AVN of proximal fragment
• 14 patients (23.7%) had non-union. No identifiable risk factors identified