Kienbock disease an overall View Mohamad Othman MD
Kienbock disease ( an overall View ) Mohamad Othman , MD 4 -10 - 2012
Definition & history - 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.
Epidemiology • 15 and 40 years • dominant wrist of men engaged in manual labor Natural history of KD remains unclear & unpredictable
Aetiology : - unknown ; theories : Fault plate hypothesis: Intrinsic ( lunate) & extrinsic factors ----- elastic deformation of trabeculae 2 ry to loading ----- fault plates ---- wall off & interfere w capillary bl. Flow ----- AVN - 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
Staging ( Modified Lichtman Classification ) Stage I: Radiographically normal lunate or with small fracture lines Stage II: Sclerosis of lunate Stage III A: Collapse or fragmentation of lunate Stage 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
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 Investigations - Plain XR : views…. . Measurements…. Staging. - CT - Scintigraphy - MRI : earliest diagnosis : uniform low signal in T 1
XR
Stahl index: Normally; B/A= 50% Carpal height ratio
CT scanning:
M R I
Differential diagnosis: - ulnar impaction synd. ( MRI) - DRUJ arthritis - Lunate Fx , intraoss ganglion, enchondroma.
Treatment Objectives : (a) precollapse (b) postcollapse Methods: Established methods: Direct vascularization Indirect vascularization ( unloading procedures): joint-levelling procedures limited carpal fusions Salvage procedures: PRC wrist arthrodesis Optional & 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 Algorithm 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 ( cont. ) Stage IIIB : -intercarpal fusions (STT and SC ) - Proximal row carpectomy ( PRC) -RSO -Lunate excision Stage IV : - conservative - Proximal row carpectomy - wrist fusion-
Radial shortening osteotomy • Approach ; volar > dorsal • 2 -3 mm ( not > 4 mm ; 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 2 nd or 3 rd metacarpal -Neck of 2 nd meatacarpal -1, 2 ICSRA - 2, 3 ICSRA - 4 th or 5 th CA - Hori technique - Pisiform -PQ + unloading procedure: - external fixator or - temporary STT-pinning or - radius osteotomy
1, 2 ICSRA VBG 2, 3 ICSRA VBG
4 th CA VBG : retrograde flow through 5 th CA from dorsal itercarpal arch
Limited carpal fusion - Objective : redistribute stresses away from lunate - Correct scaphoid malrotation 1 st - 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
Incisions for wrist denervation Core decompression of distal metaphysis of R & U
- Slides: 32