scaphoid fractures and non union
TRANSCRIPT
Scaphoid fractures and Non Union
Introduction
• Occur due to fall on outstretched arm or forced dorsiflexion injury to the wrist.
• Undisplaced fractures can be mistaken for sprains.
• Avascular necrosis occurs in estimated 13-50% of fractures.
Blood supply
• Artery to the dorsal ridge of the scaphoid-branch of radial artery.
• The branches of the artery enter the non articular portion through foramina at dorsal ridge at the waist.
• These vessels run proximally and volarly to supply the proximal pole of scaphoid.
• The vascularity depends mainly on the interosseous blood supply.
• Therefore time of healing is prolonged- 3-6 months
Clinical features
X rays
• PA view of wrist in slight ulnar deviation is helpful.
• Repeat x rays after 2 weeks of immobilization in suspected fractures.
X Rays
ImagingTest Sensitivity Specificity
Bone scintigraphy 100% 98%
MRI 95-100% 100%
X Ray 65-70% 85%
MRI
• Determine preop vascularity in a diagnosed scaphoid fracture.
• Acute fractures- Normal or decreased T1 intensity or increased T2 intensity.
• Low T1 and T2 marrow signal intensity indicates poor vascularity.
Casting and X ray• Safer approach.• Less expensive.• Unnecessary
immobilisation.• Poor interobserver
agreement.
MRI• Reduces time of
immobilisation• Better interobserver
aggreability• Find other causes of wrist
pain.• Assesment of vascularity.• Expensive.
• Obtain AP, Lateral and Oblique views.• If a scaphoid fracture is identified, do a CT for
proper surgical planning.• MRI wrist for negative or equivocal X rays.
Herbert classification
Non displaced, stable fractures
• Acute non displaced stable fractures through the waist.
• Fractures through the distal pole.• No other bony or ligamentous injury.• Scaphoid injuries in children.
J Hand Surg Am. 2008 Jul-Aug; 33(6): 988–997.
Scaphoid cast
• Just below the elbow proximally to the base of thumbnail and proximal palmar crease.
• Wrist in slight radial deviation and neutral flexion.
• Thumb in functional position and MCP joints free.
• 90-95% union in 10-12 weeks.• Take regular X rays.
• Initial long arm thumb spica justified in case of proximal fractures or those diagnosed later.
• 6 weeks.• A clinical sign of union is the strength of the
pinch of the tip of the index finger to the thumb.
Displaced, unstable fractures
• Fragments are offset more than 1mm in the AP or oblique view.
• Lunocapitate angulation > 15 deg.• Scapholunate angulation is > 45 deg.• Lateral intrascaphoid angle >45 deg• AP intrascaphoid ange <35 deg.• Height to length ratio of 0.65 or more.
Methods of fixation
• K wires• AO Cannulated screw• Herbert diffferential pitch bone screw• Acutrak screw• Herbert- Whipple Screw
Approach
• Scaphoid tubercle and FCR tendon.
• Extend the wrist in ulnar deviation, open the capsule in longitudnal axis towards the ST joint.
• Place k wires and joystick them to reduce the fractures.
• Radially deviate the wrist and direct the k wires dorsally.
• Entry point is at palmar edge of ST joint.
• Angulate guidweire 45 deg dorsally, medially and along the mid axis.
Dorsal approach
Percutaneous approach
• To visualise the axis the PA view of the wrist is obtained.
• Pronate the wrist so that the scaphoid poles are aligned and it appears as a cylinder
• Wrist is flexed until the scaphoid has a ring appearance.
• 1.14 mm K wire to be inserted at the proximal pole of the scaphoid.
• Pass the wire along the central axis of the scaphoid, through the distal pole into the palmar surface.
• Determine dorsal or palar insertion of screw based on fracture location.
• Select screw length 4mm shorter for allowing countersinking.
• Advance the screw within 1-2 mm of the opposite cortex.
Non union of scaphoid fractures
• Factors-– Gross displacement– Associated carpal injuries– Impaired blood supply.
• Displaced fractures- 92% non union incidence.• AVN-30-40 % most frequently in the proximal
third.• Delayed treatment- 88%
• Treatment options- based on vascularity.
• If the blood supply to the proximal pole is poor- vascularised bone graft is indicated.
Scaphoid Non union advanced collapse
Knoll and Trumble Algorithm
Operations for scaphoid non union
• Radial styloidectomy• Excision of proximal/distal/ entire scaphoid.• Proximal row carpectomy.• Bone grafting• Vascularised bone grafting• Partial/total wrist arthrodesis.
Styloidectomy
• Indicated alongwith grafting or excision of ulnr fragment when arthritic changes involve the scaphoid fossa.
• Enough styloid should be resected to remove entire articulation with scaphoid.
• Preserve palmar radiocarpal ligaments to prevent ulnar translocation of carpus.
Excision
• Capitate migration should be addressed by capitolunate or capito-lunate-triquetral- hamate fusions.
• Indications of excision of proximal pole-– Fragment is one fourth or less of scaphoid.– Fragment is one fourth or less of scaphoid and is
sclerotic ,comminuted or severely displaced.– Failed grafting– Arthritic changes.
Proximal Row Carpectomy
• Post traumatic degenerative conditions of the wrist.
• Healthy articular surfaces should be present between the lunate fossa of the radius and articular surface of capitate.
• Treatment of severe open carpal fracture dislocations with disruption of bony architecture and bony communition.
• Excision of lunate, triquetrum and entire scaphoid.
• Distal pole with trapezium attachment can be left for stable attachment of thumb.
Grafting operations
• First described by Matti and modified by Russe.
• Union in 80-97%.• Useful for non union without
shortening/angulation.
• Volar incision over FCR tendon ending distally over the saphoid tuberosity.
• Opening made in volar non articular cortex.
• Opposing cavities excavated.
• Cancellous graft packed +/- K wires.
Humpback deformity
• Resorption/communition at fracture site.
• Extension of proximal pole of scaphoid and lunate.
• Techniques-– Fernandez et al– Tomaino et al– Stark et al
Fernandez bone grafting technique
• Volar approach similar to Matti Russe.• Lamina spreader used to open volar site.• Fracture site curreted.• Corticocancellous bone graft harvested-
wedge shaped/ trapezoidal.• Stabilise with 1mm K- wires; proximal to distal.• Interpositonal
• Calculate- amount of resection, graft size, angular deformity on normal side.
• 1 mm drill holes in the sclerotic bone.
• Correct the deformity and shortening alongwith the dorsal rotation of lunate.
Tomaino technique
Vascularised bone grafts
• For non unions with avascular proximal pole and previous failed surgeries for salvage.
• Pronator quadratus – pedicle bone graft.(Yamamoto)
Zaidemberg
• Incision on the dorsoradial side of the wrist- centred on the radiocarpal joint.
• First dorsal compartment- identify the ascending irrigating branch of the radial artery
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