Avascular necrosis

 

AVNAVN CTAVN MRI

 

Definition

 

Loss of blood supply to the proximal pole of the scaphoid

Progressive sclerosis / fragmentation / collapse

 

Risk factors

 

Fracture location - increased risk with proximal pole fractures than waist fractures

 

Smoking

 

Blood supply

 

1.  Dorsal scaphoid branch 

- dorsal ridge artery via branch of radial artery

- supplies 70- 80% scaphoid including proximal pole

- enters through the non articular dorsal ridge

 

2.  Volar scaphoid branch

- superficial palmar arch via distal tubercle 

- distal 20% to 30% of scaphoid

 

Diagnosis

 

Xray

CT

MRI

Surgical findings - absence of bleeding upon drilling

 

Xray

 

AVNAVN

Increased sclerosis proximal pole consistent with AVN

 

Scaphoid Proximal Pole ORIF AVNAVN screw

Increased sclerosis proximal pole post surgery

 

CT

 

CT AVNAVN CT

Increased sclerosis of the proximal pole

 

AVNAVNAVN

Fragmentation and collapse of the proximal pole

 

MRI

 

Nasab et al Eur J Med Res 2025

- systematic review of MRI for detecting AVN

- MRI sensitivity of 0.6 and specificity of 0.85

- MRA sensitivity 0.77 and specificity 0.87

 

AVN MRIAVN MRIMRI AVN

Low vascularity of scaphoid on T1 MRI and reduced gadolinium uptake proximal pole scaphoid

 

Management

 

Options

 

No radiocarpal OA / SNAC

 

1. No proximal scaphoid collapse: ORIF + vascularized bone graft

2. Proximal scaphoid collapse / fragment non salvageable: reconstruction / excision

 

SNAC wrist: www.boneschool.com/SNAC-wrist

 

Pre proximal scaphoid collapse / Salvageable Post proximal scaphoid collapse / non salvageable 
AVN AVN

 

Non vascularized bone grafts + ORIF

 

Vascularized bone graft + ORIF

- volar / dorsal pedicle grafts

- free medial femoral condyle grafts

 

 

Scaphoid reconstruction

- hamate

- medial femoral condyle osteochondral autograft

- rib osteochondral autograft

 

Scaphoid excision

 

Pre-collapse / salvageable

 

avnAVNAVN

 

Options

 

Non vascularized bone grafts + ORIF

 

Vascularized bone graft + ORIF

- volar / dorsal pedicle grafts

- free medial femoral condyle grafts

 

Results

 

Cancellous bone graft

 

Putnam et al J Hand Surg Am 2019

- 12 proximal pole nonunions 

- treated with cancellous bone graft and volar plate

- 100% union

 

Non vascularized bone graft v vascularised bone graft 

 

Ferguson et al J Hand Surg Eur 2016

- meta-analysis 

- non vascularized bone graft with proximal pole AVN: union rate 62%

- vascularised bone graft with proximal pole AVN: union rate 74%

 

Vascularized bone grafts

 

Dorsal distal radius Volar distal radius Free

 

1,2 intercompartmental supraretinacular artery (ICSRA)

- branch radial artery

- travels between 1st and 2nd extensor compartment

 

 

4,5 extensor compartment artery

 

Volar carpal artery

 

Pronator quadratus

 

 

 

Medial femoral condyle 

- harvested on medial genicular artery pedicle

- pedicle sutured into radial artery

 

Iliac crest

 

 

Dorsal vascularized bone graft (VBG)

 

Papatheodorou et al Injury 2021

- 64 proximal pole nonunion with AVN

- ORIF with dorsal capsular based VBG

- union rate 86%

 

Distal radius VBG versus free medial condyle VBG

 

Jones et al JBJS Am 2008

- 22 patients with proximal pole nonunion with AVN

- distal radius VBG: union 40%

- free medial condyle VBG: union 100%

 

Free medial condyle VBG versus free iliac crest VBG

 

Al-Jabri et al J Orthop Surg Res 2014

- meta-analysis 

- 56 free medial condyle VBG: union rate 100%

- 188 free iliac crest VBG: union rate 88%

 

free MFCfree mfc

 

Volar techniques

 

Vumedi scaphoid plate + volar carpal artery

 

Dorsal techniques

 

Dorsal techniques

 

4th extensor artery VBG 1,2 ICSRA VBG

 

Vumedi 4th extensor artery VBG 

 

Youtube 1/2 ICSRA VBG
VBG 12 CSRA

 

Post collapse / non salvageable

 

AVNAVNAVN

 

Indications

 

Fragmented / collapsed proximal pole

Proximal pole too small for fixation

 

Options

 

Scaphoid reconstruction

- hamate

- medial femoral condyle osteochondral autograft

- rib osteochondral autograft

 

Scaphoid excision +/- arthroplasty

 

Results

 

Hamate reconstruction

 

Colon-Morillo et al J Hand Surg Am 2025

- 11 patients with fragmented proximal pole nonunions

- excision + ipsilateral proximal hamate transfer

- union rate 10/11

 

Free medial femoral osteochondral graft

 

Sivakumar et al Hand 2024

- systematic review of free medial femoral osteochondral graft for scaphoid reconstruction

- 94% union

- 3 patients early revision for vascular thrombosis

- 1 patient suffered a volar carpal dislocation

- 3 patients underwent salvage procedures for ongoing pain

 

Rib osteochondral autograft

 

Zechmann-Mueller et al J Hand Surg Eur 2020

- 21 patients with proximal pole nonunion treated with rib osteochondral allograft

- 100% union rate

 

Rib osteochondral autograft versus medial femoral trochlea osteochondral autograft

 

Scaphoid excision and arthroplasty

 

Cioffi et al Healthcare (Basil) 2023

- 9 partial and 10 total scaphoid prosthesis 

- custom 3D printed titanium implants + ligament reconstruction

- good results at one year

 

Techniques

 

Vumedi proximal pole reconstruction with hamate osteochondral graft video

 

Vumedi medial femoral condyle pedicle graft