Idiopathic Scaphoid Osteonecrosis | Proximal Pole Disease | Diagnosis of Exclusion
Herbert-Lanzetta Radiographic Staging
Critical Must-Knows
- Diagnosis of exclusion: Preiser is idiopathic AVN with NO acute fracture - rule out occult fracture/nonunion first
- Retrograde blood supply: dorsal scaphoid branch of the radial artery enters distally, so the PROXIMAL pole is most ischaemic
- MRI is the key test: diffuse low T1 signal of the scaphoid; Stage I is MRI-only with normal radiographs
- Kalainov MRI split: complete (entire scaphoid) vs partial (proximal pole only) necrosis - guides graft suitability
- Salvage when collapsed/arthritic: proximal row carpectomy and four-corner fusion give the most reliable pain relief
Clinical Pearls
- "Scaphoid is the 2nd most common carpal bone for AVN after the lunate
- "Proximal pole disease = retrograde, distally-entering blood supply
- "Normal X-ray does not exclude Preiser - get an MRI
- "No level I evidence and no formal guideline - treatment is staged and individualised
Clinical Imaging
Critical Preiser Disease Exam Points
It Is a Diagnosis of Exclusion
Preiser disease = idiopathic AVN of the scaphoid with NO acute fracture. Before you call it Preiser, exclude an occult fracture or established nonunion (which has its own proximal-pole AVN). The history of insidious pain without significant trauma is the giveaway.
Proximal Pole = Vulnerable
The scaphoid has a retrograde blood supply. The dorsal scaphoid branch of the radial artery enters the dorsal ridge distally and runs proximally, so the proximal pole is the watershed and the first to die - the same reason proximal pole fractures fail to unite.
MRI Is the Key Test
Plain films can be normal early (Stage I). Diffuse low T1 signal of the scaphoid confirms AVN. MRI also separates complete from partial necrosis (Kalainov), which influences whether a vascularized graft is sensible.
No Guideline - Stage-Based Care
There is no level I evidence and no society guideline. Management is built on small case series: immobilize early disease, graft viable non-arthritic scaphoids, and salvage once the carpus collapses or arthritis appears.
Quick Decision Guide
| Herbert-Lanzetta stage | Imaging | Preferred treatment | Key pearl |
|---|---|---|---|
| I | Normal X-ray, MRI positive | Immobilization, activity change, observe | Some viable scaphoids revascularise without surgery |
| II | Sclerosis / density change, no fragmentation | Vascularized bone graft or radial osteotomy (if viable, no arthritis) | Best stage for joint-preserving surgery |
| III | Fragmentation / cystic change of proximal pole | Graft if no arthritis; otherwise salvage | Assess cartilage and carpal alignment carefully |
| IV | Collapse + peri-scaphoid arthritis | Salvage: PRC or four-corner fusion | Joint-preserving surgery no longer works |
SCAPHOIDWhy the Scaphoid (and the Proximal Pole) Dies
| S | Slender shape Type 2 slender scaphoid has a sparser intra-osseous vascular network |
| C | Corticosteroids Systemic steroids - a recognised AVN risk factor |
| A | Alcohol / chemotherapy Cytotoxic drugs and alcohol implicated in case reports |
| P | Proximal pole watershed Retrograde supply enters distally - proximal pole is last to perfuse |
| H | Haematological / connective-tissue disease SLE, sickle cell, gout, vasculitis |
| O | Occupational vibration / load Repetitive impact (e.g. drill operators) |
| I | Idiopathic core By definition no acute fracture - true cause often unknown |
| D | Distal supply only No proximal nutrient vessel to rescue the proximal pole |
| S | Slender shape Type 2 slender scaphoid has a sparser intra-osseous vascular network | P | Proximal pole watershed Retrograde supply enters distally - proximal pole is last to perfuse | I | Idiopathic core By definition no acute fracture - true cause often unknown |
| C | Corticosteroids Systemic steroids - a recognised AVN risk factor | H | Haematological / connective-tissue disease SLE, sickle cell, gout, vasculitis | D | Distal supply only No proximal nutrient vessel to rescue the proximal pole |
| A | Alcohol / chemotherapy Cytotoxic drugs and alcohol implicated in case reports | O | Occupational vibration / load Repetitive impact (e.g. drill operators) |
Hook:SCAPHOID spells out both the bone and the reasons its proximal pole is so prone to avascular necrosis.
SAFCHerbert-Lanzetta Radiographic Stages
| S | Stage I - Silent X-ray Normal radiograph, MRI-only disease |
| A | Stage II - Altered density Sclerosis / density change, no fragmentation |
| F | Stage III - Fragmentation Cystic change and fragmentation of the proximal pole |
| C | Stage IV - Collapse + arthritis Carpal collapse with peri-scaphoid degeneration |
| S | Stage I - Silent X-ray Normal radiograph, MRI-only disease | F | Stage III - Fragmentation Cystic change and fragmentation of the proximal pole |
| A | Stage II - Altered density Sclerosis / density change, no fragmentation | C | Stage IV - Collapse + arthritis Carpal collapse with peri-scaphoid degeneration |
Hook:SAFC = Silent, Altered, Fragmented, Collapsed - the radiographic march of an untreated osteonecrotic scaphoid.
PFESalvage Options Once the Scaphoid Is Gone
| P | Proximal row carpectomy Excise scaphoid, lunate, triquetrum; capitate articulates with radius |
| F | Four-corner fusion Excise scaphoid, fuse capitate-hamate-lunate-triquetrum |
| E | Excision + replacement / fusion Scaphoid excision (with pyrocarbon/silastic implant historically) or total wrist fusion for end-stage |
| P | Proximal row carpectomy Excise scaphoid, lunate, triquetrum; capitate articulates with radius |
| F | Four-corner fusion Excise scaphoid, fuse capitate-hamate-lunate-triquetrum |
| E | Excision + replacement / fusion Scaphoid excision (with pyrocarbon/silastic implant historically) or total wrist fusion for end-stage |
Hook:PFE = the salvage toolkit for an arthritic or collapsed Preiser wrist - motion-preserving (PRC, four-corner) before motion-sacrificing (total fusion).
Overview and Epidemiology
Why Preiser Disease Matters
Preiser disease is rare but a classic exam topic because it forces you to reason from first principles: scaphoid vascular anatomy, the difference between AVN and nonunion, and a staged treatment algorithm where no guideline exists.
Preiser disease is idiopathic avascular necrosis (osteonecrosis) of the scaphoid occurring without an acute fracture. It was first described by Georg Preiser in 1910. The scaphoid is the second most common carpal bone to undergo osteonecrosis after the lunate (Kienbock's disease).
Demographics
- Age: typically 30-50 years
- Sex: both sexes affected; several surgical series show a female predominance
- Laterality: usually unilateral
- Rarity: only a few hundred cases in the world literature
A pooled literature review of 53 publications captured only around 170 patients in a century.
Natural History
- Early (I-II): a viable scaphoid may revascularise or remain stable
- Mid (III): fragmentation and proximal-pole volume loss
- Advanced (IV): collapse and peri-scaphoid arthritis (SNAC-like pattern)
- Timeline: months to years
Unlike acute fracture AVN, the necrosis here is primary, not the result of a displaced fragment losing its blood supply.
Preiser Disease vs Scaphoid Nonunion AVN
Both can show proximal-pole sclerosis, but Preiser disease has no fracture line - the necrosis is primary and idiopathic. In nonunion, the AVN is a consequence of a fracture that failed to heal. On MRI, Preiser typically shows necrosis confined to the zone of dead bone, whereas a nonunion shows a discrete fracture line. Getting this distinction right changes both the diagnosis and the operation.
Pathophysiology and Anatomy
Scaphoid Vascular Anatomy
The scaphoid receives roughly 70-80% of its blood (including the entire proximal pole) from the dorsal scaphoid branch of the radial artery, which enters the dorsal ridge distally and runs retrograde toward the proximal pole. The distal pole and tubercle are supplied by volar branches. Because no vessel enters the proximal pole directly, it is the watershed and dies first - the same anatomy that explains delayed union of proximal pole fractures.
Aetiology is multifactorial and, by definition, often unknown:
Risk Factors and Associations
-
Slender ("type 2") scaphoid morphology
- A narrow scaphoid has a sparser intra-osseous vascular network
- Over-represented in operative Preiser series compared with the wider "type 1" scaphoid
-
Repetitive load and vibration
- Manual labour, drilling, impact sports
- Cumulative microtrauma to a marginally perfused bone
-
Drugs and systemic disease
- Corticosteroids, cytotoxic chemotherapy, alcohol
- Systemic lupus erythematosus, vasculitis, sickle cell disease, gout, renal disease
-
Idiopathic
- In many patients no cause is ever identified - this is the "core" Preiser group
Pathophysiology cascade:
- Compromised perfusion of a marginally vascularised (often slender) scaphoid
- Ischaemia of the proximal pole (the watershed zone)
- Osteocyte death; dead trabecular bone is not resorbed, producing relative sclerosis on X-ray
- Subchondral microfracture and fragmentation
- Loss of scaphoid height, carpal malalignment (DISI) and instability
- Peri-scaphoid radiocarpal and midcarpal arthritis
Three-Zone MRI Pattern
A radiology study described a three-layered scaphoid in Preiser disease: a proximal zone of osteonecrosis, a middle zone of repair, and a distal zone of viable marrow. Pathological fractures occurred only within the necrotic zone. This maps neatly onto the retrograde, distal-to-proximal blood supply.
Why Sclerosis Appears
Increased density does not mean "more bone". Living bone around the dead segment continues to be remodelled and partly resorbed, while the dead bone is not - so the necrotic area looks relatively dense on radiographs (the same principle as in Kienbock's and femoral head AVN).
Classification Systems
Herbert-Lanzetta Classification (Radiographic)
The original and most widely used staging system, based on plain radiographs and treatment implications.
| Stage | Radiographic findings | Scaphoid status | Treatment approach |
|---|---|---|---|
| I | Normal radiograph; MRI shows AVN | Structurally intact | Immobilization, observation |
| II | Sclerosis / density change, normal shape | Intact, no fragmentation | Vascularized graft or radial osteotomy |
| III | Fragmentation / cystic change | Proximal pole losing volume | Graft if no arthritis, else salvage |
| IV | Collapse with peri-scaphoid arthritis | Fragmented, arthritic carpus | Salvage (PRC, four-corner fusion) |
Stage IV is the prognostic watershed: once peri-scaphoid arthritis is established, joint-preserving surgery is no longer effective and salvage is required.
Clinical Assessment
History
- Pain: insidious radial-sided / dorsal wrist pain, worse with activity
- No significant trauma: or pain disproportionate to a trivial injury
- Weakness: reduced grip strength
- Stiffness: progressive loss of wrist motion
- Risk factors: steroid use, chemotherapy, connective-tissue disease, vibration exposure
A drill operator or manual worker with months of unexplained radial wrist pain is a classic vignette.
Examination
- Tenderness: over the anatomical snuffbox / scaphoid
- Swelling: dorsoradial fullness
- ROM: reduced flexion-extension, painful at extremes
- Grip: weak and painful
- Watson (scaphoid shift) test: may be positive if carpal instability has developed
Findings are non-specific; imaging makes the diagnosis.
Differential Diagnosis of Radial Wrist Pain
Radial-sided wrist pain in an adult has several mimics. MRI is the single best discriminator: Preiser disease shows diffuse low T1 marrow signal of the scaphoid without a fracture line, whereas the alternatives below have characteristic alternative patterns.
Differential Diagnosis
| Condition | Typical features | Key imaging discriminator | Distinguishing point from Preiser |
|---|---|---|---|
| Preiser disease | Insidious radial wrist pain, no acute fracture | Diffuse low T1 scaphoid signal, NO fracture line | Primary idiopathic AVN of an intact scaphoid |
| Scaphoid nonunion (with AVN) | Prior wrist injury, snuffbox pain | Discrete fracture line plus proximal-pole sclerosis | AVN is secondary to a fracture that failed to unite |
| Occult / acute scaphoid fracture | Acute fall on outstretched hand, focal tenderness | Fracture line on MRI/CT, bone oedema | Acute trauma and a true fracture, not idiopathic AVN |
| Scapholunate ligament injury | Trauma, dorsal SL tenderness, positive Watson | SL gap (Terry-Thomas), DISI; scaphoid marrow normal | Ligamentous instability; scaphoid signal is normal |
| De Quervain tenosynovitis | Radial styloid pain, positive Finkelstein | Tenosynovitis of first dorsal compartment; bone normal | Tendon, not bone, pathology |
| Radioscaphoid (STT) osteoarthritis | Older patient, base-of-thumb / radial pain | Joint-space loss and osteophytes; no diffuse AVN | Degenerative joint disease rather than osteonecrosis |
Controversies and Areas of Uncertainty
Unresolved Questions Examiners Probe
Preiser disease has no level I evidence and no consensus guideline. A strong candidate acknowledges the uncertainty rather than overstating any single procedure.
Does it even exist as one entity?
Preiser's original 1910 description was controversial and some early "cases" were probably unrecognised fractures. Modern authors restrict the term to genuinely idiopathic AVN with no fracture, but the boundary with occult fracture and nonunion remains debated.
Surgery vs conservative care
A systematic review found surgery gave greater pain relief than conservative treatment in Stages II-III, but the evidence is entirely Level IV case series. Some early, viable scaphoids revascularise with immobilization alone, so not every patient needs an operation.
Vascularized graft vs salvage
A large single-centre series found pedicled vascularized bone grafts gave functional outcomes similar to salvage procedures but preserved the scaphoid in about 70% of cases - so the trade-off (preserve a partly dead bone vs remove it) is genuinely unsettled.
Can you revascularise the proximal pole?
Even when grafts improve MRI signal, revascularisation of the proximal pole is frequently incomplete, and arthritis can still progress. This tempers enthusiasm for grafting in wholly necrotic (Kalainov type 1) scaphoids.
Role of radial osteotomy
Closing radial wedge osteotomy can relieve pain and preserve motion, but in published series radiographic stage still progressed in many patients - suggesting it is symptom-modifying rather than disease-modifying.
PRC vs four-corner fusion
As in other end-stage carpal collapse, both salvage options give reliable pain relief with broadly comparable function; choice is driven by cartilage status, demand and surgeon preference rather than high-quality comparative data.
Investigations
Investigation Protocol
PA, lateral and scaphoid (ulnar-deviation) views. Look for scaphoid sclerosis (Stage II), fragmentation/cysts (Stage III), collapse and peri-scaphoid arthritis (Stage IV), and any DISI on the lateral. Films are normal in Stage I, so a normal radiograph never excludes the diagnosis.
T1 and T2 sequences (consider contrast). Diffuse low T1 signal confirms AVN; absence of a fracture line distinguishes Preiser from nonunion. MRI detects Stage I disease, assesses lunate viability, and separates complete vs partial necrosis (Kalainov) to guide graft suitability.
For bony detail and surgical planning. Defines fragmentation, cyst location, collapse and any subtle fracture line. Sagittal-oblique reformats along the scaphoid axis are most useful.
Direct cartilage assessment. Allows grading of articular damage and can be combined with debridement; helps decide between joint-preserving surgery and salvage when imaging is equivocal.
Key Imaging Points
| Modality | What it shows | Role in Preiser disease |
|---|---|---|
| Radiograph | Sclerosis, fragmentation, collapse, arthritis | Herbert-Lanzetta staging; normal in Stage I |
| MRI | Diffuse low T1 marrow signal, extent of necrosis | Confirms diagnosis; Kalainov complete vs partial; detects Stage I |
| CT | Trabecular detail, cysts, fracture line, collapse | Surgical planning; excludes occult fracture/nonunion |
Management Algorithm
Conservative Management
Indications: Stage I disease, viable scaphoid, low-demand or reluctant patient, significant comorbidity.
Conservative Treatment Steps
Cast or splint for several weeks to months to unload the scaphoid and allow revascularisation. Combine with activity / occupational modification (e.g. moving away from vibration or heavy impact work). Monitor with serial radiographs and MRI.
Avoid heavy load and vibration. NSAIDs for symptom control. Hand therapy to maintain motion.
Repeat MRI to detect revascularisation or progression. Some early, viable scaphoids recover (as in the illustrated case); others progress and need surgery.
Conservative care is most appropriate for genuinely early, viable disease - it is temporizing once fragmentation or arthritis appears.
Treatment Algorithm by Stage
| Stage | Preferred treatment | Alternative | Notes |
|---|---|---|---|
| I | Immobilization + activity change | Observation with serial MRI | Some viable scaphoids revascularise |
| II | Vascularized bone graft | Closing radial wedge osteotomy | Best window for joint preservation |
| III | VBG if no arthritis | Salvage if cartilage damaged | Decision hinges on arthritis and necrosis extent |
| IV | PRC or four-corner fusion | Total wrist fusion (end-stage) | Joint-preserving surgery no longer effective |
Complications
Complications by Treatment
| Treatment | Early complications | Late complications | Management |
|---|---|---|---|
| Conservative | Persistent pain | Progression to collapse / arthritis | Convert to surgery |
| Vascularized graft | Pedicle injury, stiffness | Incomplete revascularisation, ongoing arthritis | Salvage procedure |
| Radial wedge osteotomy | EPL rupture, hardware irritation, DRUJ symptoms | Stage progression despite pain relief | Tendon reconstruction, revision |
| PRC | Stiffness, CRPS | Radiocapitate arthritis over time | Convert to fusion |
| Four-corner fusion | Nonunion, hardware prominence | Adjacent-joint arthritis | Revision / total fusion |
General Complications
Progression of disease (untreated or after symptom-only surgery):
- Fragmentation, scaphoid collapse, DISI and peri-scaphoid arthritis
- Some early viable scaphoids instead revascularise and stabilise
Complex regional pain syndrome (CRPS):
- Risk after any wrist surgery; minimise with early motion and good analgesia
Stiffness:
- Common after prolonged immobilization or fusion; early hand therapy mitigates it
Clinical Relevance and Outcomes
Representative Outcomes
| Treatment | Pain relief | Motion | Evidence |
|---|---|---|---|
| Conservative (early, viable) | Variable; some full recovery | Often preserved | Case reports / small series |
| Vascularized bone graft | Improved in most | Preserved (around half of normal) | Level IV series |
| Radial wedge osteotomy | Good pain relief | Largely retained | Small Level V series |
| PRC / four-corner fusion | Reliable pain relief | Roughly 50% of normal | Level IV salvage data |
Prognostic factors:
| Factor | Better outcome | Worse outcome |
|---|---|---|
| Stage at diagnosis | I-II | III-IV |
| Necrosis extent (Kalainov) | Partial (type 2) | Complete (type 1) |
| Cartilage / arthritis | Intact | Peri-scaphoid arthritis |
| Carpal alignment | Stable | DISI / collapse |
Bottom line: outcomes are driven by when the disease is caught. Caught early and viable, the scaphoid may be preserved or even revascularise; caught late with collapse and arthritis, salvage gives dependable pain relief but never restores a normal wrist.
Evidence Base
- Updated review of 53 publications and 170 patients since Preiser's 1910 description
- Scaphoid is the second most frequent carpal bone for avascular necrosis after the lunate
- Two modern imaging-based classifications now supplement the original Herbert-Lanzetta radiographic system
- Proposes a simple staged treatment algorithm given the absence of formal guidelines
- 10 patients with primary scaphoid osteonecrosis imaged with radiographs, CT and contrast-enhanced MRI
- A three-layered architecture was found: proximal necrosis, middle repair zone, distal viable marrow
- Pathological fractures occurred exclusively within the necrotic zone, unlike scaphoid nonunion
- Three morphological stages described; the initial stage is visible only on MRI
Exam Viva Scenarios
Use these scenarios to practise clinical reasoning and management decisions
Scenario 1: Radial Wrist Pain with a Normal X-ray
"A 36-year-old male drill operator presents with 4 months of insidious radial-sided wrist pain and no clear injury. Snuffbox tenderness is present. Plain radiographs of the wrist are reported as normal. How do you proceed?"
Scenario 2: Viable Scaphoid, No Arthritis
"A 40-year-old woman has 8 months of dorsoradial wrist pain. Radiographs show scaphoid sclerosis without fragmentation. MRI confirms avascular necrosis limited to the proximal pole with viable distal bone, and there is no radiocarpal arthritis or carpal instability. What are her options?"
Scenario 3: Collapsed, Arthritic Scaphoid
"A 55-year-old presents late with chronic wrist pain, stiffness and weakness. Radiographs show scaphoid fragmentation and collapse with peri-scaphoid radiocarpal arthritis and a DISI deformity. MRI shows necrosis of the whole scaphoid. How do you manage this, and what does the evidence say?"
MCQ Practice Points
Which Carpal Bone
Q: Which carpal bone is the second most common site of avascular necrosis after the lunate? A: The scaphoid - idiopathic scaphoid osteonecrosis is termed Preiser disease.
Why the Proximal Pole
Q: Why is the proximal pole of the scaphoid most affected in Preiser disease? A: The scaphoid has a retrograde blood supply - the dorsal scaphoid branch of the radial artery enters the dorsal ridge distally and runs proximally, so the proximal pole is the watershed and dies first.
Key Investigation
Q: What is the key investigation for diagnosing early Preiser disease? A: MRI - it detects diffuse low T1 marrow signal (Stage I) before radiographic changes and distinguishes Preiser from scaphoid nonunion by the absence of a fracture line.
Two Classifications
Q: Name the two main classification systems used in Preiser disease. A: The Herbert-Lanzetta radiographic staging (four stages) and the Kalainov MRI classification (complete vs partial necrosis).
When to Graft
Q: When is a vascularized bone graft appropriate in Preiser disease? A: In early disease (Herbert I-II) with a viable scaphoid and no radiocarpal arthritis or carpal instability - ideally a partial (Kalainov type 2) necrosis with viable distal bone.
Salvage of Choice
Q: What is the salvage procedure favoured for advanced (Stage III-IV) Preiser disease in the systematic review evidence? A: Proximal row carpectomy - it gives reliable pain relief and preserves roughly half of wrist motion, provided the capitate head and lunate fossa cartilage are intact.
Guidelines, Registries & Global Practice
Global epidemiology. Preiser disease is rare worldwide - only a few hundred cases exist in the literature, and most hand surgeons see only one or two in a career. It clusters in adults aged 30-50, with several surgical series reporting a female predominance, and is associated with corticosteroids, chemotherapy, alcohol, connective-tissue disease and a slender scaphoid morphology. There is no population incidence figure and no implant registry, because the operations performed (grafts, osteotomies, carpectomies and fusions) are not arthroplasty.
No single global guideline - practice rests on case-series evidence. No society publishes a formal Preiser treatment guideline. Practice converges on a staging-driven algorithm derived from Level IV-V evidence.
How Practice Differs by Setting and School of Thought
| Source / setting | Staging emphasis | Early disease (Stage I-II) | Advanced (III-IV) |
|---|---|---|---|
| North American (ASSH teaching, Mayo series) | Herbert-Lanzetta + Kalainov MRI | Vascularized bone graft for viable, non-arthritic scaphoids | PRC favoured; four-corner fusion if capitate arthritic |
| European (FESSH / French hand-surgery centres) | Herbert-Lanzetta + MRI necrosis extent | Vascularized graft (Zaidemberg-type) in early stages | Scaphoidectomy +/- implant, PRC or carpal arthrodesis |
| Japanese / Asian centres | Herbert-Lanzetta + Kalainov + DISI assessment | Closing radial wedge osteotomy as less-invasive option | Conservative care common in elderly; salvage if disabling |
| Limited-resource settings | Plain radiographs (MRI often unavailable) | Immobilization and activity modification | Total wrist fusion as reliable, low-cost salvage |
Registry and high- vs limited-resource practice. Where MRI is freely available, early (Stage I) disease is detected and viable scaphoids can be grafted or simply observed before collapse. Where MRI is scarce, diagnosis is later and total wrist fusion becomes the dependable salvage because it needs no specialist implant and reliably abolishes pain. Vascularized grafting and microsurgical reconstruction are concentrated in specialist hand units.
Consent essentials (universal). For joint-preserving surgery, counsel that proximal-pole revascularisation is often incomplete and arthritis may still progress. For salvage surgery, counsel explicitly on the motion-versus-pain-relief trade-off (PRC and four-corner fusion preserve some motion; total fusion removes motion but most reliably relieves pain), and on progression risk if early disease is managed non-operatively.
PREISER DISEASE
Clinical summary
Key Concepts
- •Idiopathic AVN of the scaphoid with NO acute fracture
- •2nd most common carpal AVN after the lunate (Kienbock's)
- •Proximal pole most affected - retrograde, distally-entering blood supply
- •Diagnosis of exclusion - rule out occult fracture / nonunion first
Classifications
- •Herbert-Lanzetta (radiographic): I normal X-ray, II sclerosis, III fragmentation, IV collapse + arthritis
- •Kalainov (MRI): complete (whole scaphoid) vs partial (proximal pole) necrosis
- •Schmitt 3-zone model: proximal necrosis, middle repair, distal viable
Investigations
- •MRI = key test: diffuse low T1, no fracture line; detects Stage I
- •Radiographs: sclerosis, fragmentation, collapse, arthritis (normal in Stage I)
- •CT: bony detail, exclude occult fracture, surgical planning
Treatment by Stage
- •Stage I: immobilization + activity change, serial MRI
- •Stage II: vascularized bone graft (or radial wedge osteotomy)
- •Stage III: graft if no arthritis, else salvage
- •Stage IV: PRC or four-corner fusion; total fusion for end-stage
Exam Pearls
- •Normal X-ray does NOT exclude Preiser - order an MRI
- •VBG only for early, viable, non-arthritic scaphoids
- •Proximal-pole revascularisation after grafting is often incomplete
- •No level I evidence and no formal guideline - staged, individualised care