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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