Kienbock disease( an overall View )

Mohamad Othman , MD4-10 - 2012

- KD ( or lunatomalacia ) is an idioopathic AVN of carpal lunate which may lead to collapse of the bone and arthritis in the advanced stage

- first described in 1843 by Peste in cadaver dissections. - Robert Kienbock ( 1910) , a radiologist, described the x-ray changes associated w KD.

Definition & history

Epidemiology• 15 and 40 years • dominant wrist of men engaged in manual labor

Natural history of KD remains unclear & un-predictable

- unknown ; theories :

Fault plate hypothesis:Intrinsic ( lunate) & extrinsic factors ----- elastic deformation of trabeculae 2ry to loading ----- fault plates ---- wall off & interfere w capillary bl. Flow ----- AVN

Aetiology :

- repetitive microtrauma in the lunate at risk ( predisposed lunate ) ;

Extrinsic factors:- capitate- lunate loading- ulnar variance : ulnar-negative variant wrist is common association ( Hulten, 1928). ulnar-positive variant- load type - instability

Intrinsic factors:- shape of lunate- trabecular pattern- cortical load- lunate vascular anatomy

Stage I: Radiographically normal lunate or with small fracture lines

Stage II: Sclerosis of lunateStage III A: Collapse or fragmentation of lunateStage IIIB: Lunate collapse with carpal malalignment ie; proximal migration of capitate (carpal height ratio <0.54 ± 0.03) and fixed hyperflexed rotation of scaphoid( DISI)[radioscaphoid angle > 60]Stage IV: Generalized wrist arthrosis

Staging ( Modified Lichtman Classification )

Stage-I Stage-II

Stage-III Stage-IV

Clinical picture

- Complaint may precede XR changes- Varies according to stage- Pain. Tenderness ,swelling, clunk w deviation, dec ROM , weak grip

- Plain XR : views….. Measurements…. Staging.

- CT- Scintigraphy - MRI : earliest diagnosis : uniform low signal in T1

Investigations

XR

Stahl index:Normally;B/A= 50%

Carpal height ratio

CT scanning:

MRI

Differential diagnosis:

- ulnar impaction synd. ( MRI)- DRUJ arthritis- Lunate Fx , intraoss ganglion, enchondroma.

Objectives : (a) precollapse (b) postcollapse

Methods:

Established methods:Direct vascularizationIndirect vascularization ( unloading procedures): joint-levelling procedures limited carpal fusions Salvage procedures: PRC wrist arthrodesisOptional & controversial methods:- conservative-Lunate excision ± replacement ( PL tendon ball , silicon, titanium)- Core decompression of distal metaphysis of R & U- Temporary ST pinning ; 3-6 mo . Stage III- External fixation- RSO in stage IIIB- RO + VBG in stage III - Wrist denervation; stage IV- Arthroscopic debridement

Treatment

Stage I: Controversial ; not completely-unload lunate.Choice in transient ischemia. After 3 mo, aggressive management as stage II

Stage I, II, or IIIA with Ulnar-Negative Variance : (1) Lunate unloading by joint-leveling procedures ( RS > UL) or (2) Lunate revascularization by VBG

Stage I, II, or IIIA with Ulnar-Positive or Ulnar-Neutral Variance : (1) unloading by Capitate shortening ± capitate-hamate fusion or radius ost. (2) VBG ( ± STT-pinning)

Treatment Algorithm

Stage IIIB :-intercarpal fusions (STT and SC )- Proximal row carpectomy ( PRC)-RSO-Lunate excision

Stage IV :- conservative- Proximal row carpectomy- wrist fusion-

Treatment Algorithm ( cont.)

Radial shortening osteotomy

• Approach ; volar > dorsal• 2-3mm ( not > 4mm ; UC impaction )• Meaphyseal / meta-diaphyseal• Not decrease ROM• Not in ulna positive wrist

Ulnar lengthening osteotomy

Disadvantages;

Distal radius wedge osteotomy

- Stage II or III w ulna-neutral or positive wrist- Lateral closing wedge osteotomy : decrease RU-inclination thus shifting press from lunate- Medial closing osteotomy or lat opening wedge o- Step- cut osteotomy

Capitate shortening osteotomy

CSO + capito-hamate fusion

VBG Sources: - Base of 2nd or 3rd metacarpal-Neck of 2nd meatacarpal-1,2 ICSRA - 2,3 ICSRA - 4th or 5th CA- Hori technique- Pisiform-PQ+ unloading procedure: - external fixator or - temporary STT-pinning or - radius osteotomy

1,2 ICSRA VBG 2,3 ICSRA VBG

4th CA VBG : retrograde flow through 5th CA from dorsal itercarpal arch

Limited carpal fusion

- Objective : redistribute stresses away from lunate- Correct scaphoid malrotation 1st

- SC / STT-Decreases ROM-Excise lunate; only if fragmented w marked synovitis

Triscaphe (STT) fusion

SC- fusion

Temporary STT-pinning

Prox raw carpectomy

Total wrist fusion

Core decompression of distal metaphysis of R & U

Incisions for wrist denervation

THANK YOU

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الله ورحمة

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