Management of Non-Union of Scaphoid Fracture

MS Orthopaedics Long Answer

INTRODUCTION

ANATOMY AND BLOOD SUPPLY

• Approximately 75% of the scaphoid is covered by articular cartilage, severely limiting areas for vascular ingrowth.
• Main blood supply (proximal ¾): Dorsal branch of the radial artery enters at the dorsal ridge just distal to the waist and flows in a retrograde (distal-to-proximal) fashion toward the proximal pole.
• Distal ¼: Superficial volar branches of the radial artery enter at the distal tubercle.

CAUSES / RISK FACTORS FOR NONUNION

CLASSIFICATION

Herbert & Fisher Classification (Most used clinically)

PATHOMECHANICS: HUMPBACK DEFORMITY & SNAC WRIST

1. Humpback deformity — proximal fragment rotates dorsally into extension; distal fragment flexes (palmar flex). Fisk described this triplane angulation.
2. DISI (Dorsal Intercalated Segment Instability) — unsupported carpus collapses; lunate tilts dorsally.
3. SNAC wrist progression (similar to SLAC but due to scaphoid nonunion):

CLINICAL FEATURES

• History: Often young male, fall on outstretched hand; may recall an old or "sprained" wrist injury that never fully resolved.
• Symptoms: Chronic radial-sided wrist pain, swelling, reduced grip strength, limited wrist extension, activity-related pain.
• Signs:
  • Tenderness in the anatomical snuffbox
  • Tenderness over the volar scaphoid tubercle
  • Reduced wrist extension and grip strength

INVESTIGATIONS

Radiology

• Plain X-ray (PA, lateral, scaphoid view): Shows sclerosis at fracture ends, cyst formation, resorption gap, cortical breach. Humpback deformity and DISI may be visible on lateral view.
• CT scan (gold standard for nonunion assessment):
  • Best modality to assess union, degree of displacement, humpback angle, and intrascaphoid angle.
  • CT of the contralateral normal wrist helps plan graft size.
  • Can identify sclerosis and cavitation of proximal pole (suggests AVN).
• MRI:
  • Best modality for soft tissue assessment, AVN evaluation, and associated ligamentous injuries.
  • Low T1 signal in proximal pole suggests AVN (sensitivity limited — CT proximal pole sclerosis has 100% specificity but only 60% sensitivity for AVN).
  • Gold standard for AVN remains intraoperative punctate bleeding from the proximal pole when the tourniquet is released.
• Bone scan: Useful if initial X-rays are negative with high clinical suspicion (largely replaced by MRI in modern practice).

MANAGEMENT

Goals of Treatment (Rockwood & Green's, 10th ed.)

1. Relieve symptoms
2. Correct carpal malalignment (humpback deformity, DISI)
3. Achieve bony union
4. Delay or prevent onset of wrist arthrosis (SNAC)

Surgical Principles

• Complete resection of the nonunion site back to bleeding bone on both sides
• Restore scaphoid length and correct malalignment
• Correct carpal malalignment (reduce DISI)
• Preserve blood supply to distal and proximal poles
• Achieve bone apposition with appropriate graft
• Achieve stability (screw fixation ± K-wires or plate)

TREATMENT OPTIONS

A. Fixation Without Bone Grafting

• For stable nonunions (Type D1) with intact cartilage cap and no significant deformity.
• Percutaneous or open headless compression screw (e.g., Herbert screw, Acutrak).
• Both open and arthroscopically assisted approaches produce reliably good results in this setting.
• Union rates >90% expected when properly selected.

B. Non-Vascularized Bone Grafting

• Cancellous-only graft: Shorter time to union (~11 weeks) — better regenerative capacity
• Corticocancellous graft: Better correction of carpal alignment (humpback)

1. Matti-Russe technique — Volar cortical strut graft (inlay) ± K-wires. Historical gold standard; suitable for stable nonunion with minimal deformity. Union rates ~85-90%.
2. Fisk-Fernandez technique — Volar distal radius wedge graft designed to correct humpback deformity. Corrects scaphoid length and DISI deformity. The current favored technique for nonunions with humpback deformity.

C. Vascularized Bone Grafting

• Proximal pole nonunion with suspected or confirmed AVN
• Failed previous nonunion surgery
• Prolonged nonunion (relative indication)
• Scaphoid waist nonunion with reduced vascularity

• 1,2-ICSRA graft (Zaidemberg graft): First choice for proximal pole AVN; union rates 27–100% (variable results with established AVN).
• Medial Femoral Condyle (MFC) free flap: Superior option when both humpback deformity AND avascular proximal pole co-exist. Corticoperiosteal graft with excellent vascularity; recent systematic review (Zhou et al., J Reconstr Microsurg 2022 — PMID: 34905783) confirms good outcomes.

D. Fixation Method

• Volar approach (FCR route): For nonunions requiring correction of humpback deformity/DISI; allows correction from the compression side.
• Dorsal approach: For proximal pole nonunions; better access to small proximal fragment.

E. Arthroscopic-Assisted Fixation (Emerging technique)

• Arthroscopic debridement of nonunion site + percutaneous screw fixation ± bone grafting.
• Advantages: Improved visualization, minimal disruption of blood supply, direct assessment of graft containment and reduction.
• Can be combined with non-vascularized corticocancellous or cancellous grafting.
• Systematic review (Basso et al., Acta Biomed 2023 — PMID: 37850769) reports promising union rates.

MANAGEMENT OF SNAC WRIST (Salvage Procedures)

• Both improve pain and subjective outcomes
• PRC: marginally superior motion, fewer complications
• 4-corner fusion: lower risk of subsequent osteoarthritis

SURGICAL TECHNIQUE — FISK-FERNANDEZ (Standard for Humpback Nonunion)

1. Volar approach via FCR tendon sheath
2. Incise volar radioscaphoid capsule (avoid damaging RSC ligament)
3. Identify nonunion site; resect fibrous/sclerotic tissue to bleeding bone on both sides
4. Temporary radiolunate K-wire to correct DISI and reduce lunate
5. Assess residual defect; plan corticocancellous wedge graft from distal radius or iliac crest
6. Interpose wedge graft to correct intrascaphoid angle and restore scaphoid length
7. Insert central axis guidewire; confirm central placement on fluoroscopy
8. Insert cannulated headless compression screw over guidewire
9. Confirm correction of DISI on intraoperative fluoroscopy
10. Postoperatively: short arm thumb spica cast until CT confirms >50% bridging (typically 8–12 weeks)

POOR PROGNOSTIC INDICATORS

• Prolonged nonunion duration (>5 years)
• Prior failed surgery (revision cases)
• Proximal pole nonunion
• Absence of punctate bleeding from proximal pole intraoperatively (confirmed AVN)
• Smoking
• Associated humpback deformity uncorrected at surgery

COMPLICATIONS

• Persistent nonunion — most common failure
• AVN of proximal pole — may require revision with vascularized graft or salvage procedure
• Hardware complications — screw prominence, malposition
• SNAC arthritis progression despite union
• Donor site morbidity — iliac crest (pain, hernia), proximal tibia (pain)
• Flexor tendon injury during volar approach (FCR, FPL)

OUTCOMES

SUMMARY ALGORITHM

Scaphoid Nonunion
        │
        ├─ No deformity, intact cartilage cap, D1 (fibrous)
        │         → Screw fixation ± minimal grafting (arthroscopic or open)
        │
        ├─ Humpback deformity/DISI, viable proximal pole (punctate bleeding present)
        │         → Fisk-Fernandez volar wedge graft (distal radius/iliac crest) + screw
        │
        ├─ Proximal pole AVN (no intraoperative bleeding)
        │         ├─ Waist nonunion only → 1,2-ICSRA vascularized graft + screw
        │         └─ Humpback + AVN → MFC free flap + screw (volar approach)
        │
        └─ SNAC wrist established
                  ├─ Stage I → Radial styloidectomy ± neurectomy
                  ├─ Stage II → PRC or 4-corner fusion
                  └─ Stage III → Total wrist fusion

REFERENCES

• Rockwood and Green's Fractures in Adults, 10th Edition (2025) — Chapter 44: Scaphoid Fractures
• Miller's Review of Orthopaedics, 9th Edition — Chapter 7: Carpal Fractures
• Duncumb JW et al. Bone grafting for scaphoid nonunion surgery: systematic review and meta-analysis. Bone Joint J 2022. PMID: 35491585
• Zhou KJ et al. Free medial femoral condyle flap for reconstruction of scaphoid nonunion: systematic review. J Reconstr Microsurg 2022. PMID: 34905783
• Basso MA et al. Scaphoid fracture non-union: systematic review of arthroscopic management. Acta Biomed 2023. PMID: 37850769

1. Introduction — definition and incidence
2. Anatomy & Blood Supply — the essential foundation explaining why nonunion occurs
3. Risk Factors — in a table for quick recall
4. Classification — Herbert & Fisher (the most tested classification)
5. Pathomechanics — humpback deformity, DISI, and SNAC staging (I–III)
6. Clinical Features & Investigations — including the role of CT, MRI, and intraoperative assessment
7. Management — organized by type:
   • Fixation alone (Type D1)
   • Non-vascularized bone graft (Matti-Russe, Fisk-Fernandez)
   • Vascularized bone graft (1,2-ICSRA, MFC free flap)
   • Fixation technique (screw vs. K-wire vs. plate)
   • Arthroscopic-assisted (emerging)
8. Salvage for SNAC wrist — by stage
9. Operative steps for Fisk-Fernandez (commonly asked)
10. Prognosis, complications, outcomes
11. Decision algorithm
12. Current evidence citations (3 systematic reviews/meta-analyses from 2022–2023)