RHEUMATOID THUMB DEFORMITIES
Nalebuff’s classification of thumb deformities
TYPE I Boutonniere Deformity
TYPE II Boutonniere Deformity with CMC subluxation
TYPE III Swan neck deformity + adduction
TYPE IV Gamekeeper’s thumb
TYPE V Swan neck deformity
TYPE I (BOUTONNIERES DEFORMITY)
· most common deformity
o IPJ hyperextension
o MCPJ flexion
· Disease may be at MCPJ (more common) or IPJ
Mechanisms
MCPJ synovitis
1. attenuation of EPB and stretching of the extensor hood leads to flexion deformity
2. displacement of the EPL ulnarward and volar
3. volar subluxation of the proximal phalanx on the metacarpal as collaterals elongate
4. intrinsics (APB, Adductor pollicis) are stretched and elongate distally and volar
5. altered pull of EPL and intrinsics lead to more flexion of MCPJ and hyperextension of the IPJ
6. 1st metacarpus becomes radially abducted to compensate for MP flexion
IPJ volar laxity
1. attenuation of volar plate from synovitis or FPL rupture
2. MP flexion and thus 1st metacarpal abduction is not as severe
· Extrinsic minus position in that EPL rupture at wrist produces same appearance
· early stages are passively correctable and later MCPJ first becomes fixed and then IPJ
Treatment
3 clinical stages
Stage 1 (Early)
· Features
1. deformity correctable passively
2. stable laterally after reduction
3. good articular surface
1. synovectomy
o alone has not been shown to alter the course of the disease
2. EPL rerouting
o EPL rerouted through dorsal capsule and attached back to itself
o corrects the MP flexion and this means that the intrinsic muscles of thumb take over extension of the IPJ
o the intrinsic checked to be in the appropriate position as they are now the only extensors of the terminal phalanx
o K-wire across the MPJ and IP splinted in extension
o exercises for IPJ started and resting splint
o K-wire out at 4 weeks and splint MPJ for further 2 weeks
o high late recurrence rate (64%) – some recommend fusion for most and MPJ arthroplasty for the low demand patient requiring IPJ fusion
Stage 2 (moderate)
· fixed MPJ with or without intra-articular destruction
· IPJ passively correctable
· MCPJ fusion if other joints OK - provides excellent results and halts Boutonnière deformity;
· If other joints arthritic then MCPJ arthropasty combined with EPL rerouting
Stage 3 (severe)
· most difficult to treat
· MCP fixed joint flexion deformity and fixed IPJ hyperextension deformity
· Arthrodesis of both joints produces poor function
· most common procedure is IPJ fusion and MCPJ arthroplasty
TYPE III (SWAN NECK DEFORMITY)
· second most common deformity
o flexed adducted CMC
o hyperextended MCPJ
o flexed IPJ
· disease begins at CMCJ
Mechanism
· synovitis leads to dorsal and radial subluxation of the CMCJ during grasp
· adduction contracture of the metacarpal
· hyperextension of the MCPJ develops secondary to the adduction as patient attempts to grasp
Treatment
3 Stages
1st Stage (Early)
· painful joint, weak pinch and varying radiographic changes
· minimal CMCJ deformity with minimal subluxation and no MCPJ changes
· medical management and splinting 2-4 months, occasional steroid injections in the 1st instance
· surgical treatment for pain and failure of conservative management
§ tendon interpositional arthroplasty with ligament suspension
§ CMCJ implant arthroplasty not durable (25% failure)
2nd stage (Moderate)
· variable degrees of CMCJ deformity
· mild and passively correctable MCPJ hyperextension
· unless pain is significant, these patients function well except for weak grip
· interpositional arthroplasty of the CMCJ and volar tenodesis/sasamoidesis of the MCPJ
· MCPJ fusion for severe deformity or joint destruction (arthroplasty not performed for MCPJ hyperextension)
3rd stage (Severe)
· Advanced deformity
· CMCJ dislocation, fixed adduction contracture and fixed MCPJ hyperextension deformity
· poor pinch and unable to grasp objects as severe contracture of the 1st web
· CMCJ hemiarthroplasty / resectional arthroplasty with MCPJ fusion
· occasional release the 1st dorsal interosseous or adductor pollicis or overlying fascia or all three
· Z plasty for 1st web space needed rarely as tight skin in RA patients stretches after soft tissue releases
· with SLE CMCJ fusion better as more ligamentous instability
TYPE IV (GAMEKEEPER'S DEFORMITY)
· characterized by an abduction deformity of the MCPJ with secondary adduction of the thumb metacarpal
· synovitis of the MCPJ stretches the ulnar collateral ligament
· secondarily develop adduction of the metacarpal
· pathology limited to the MCPJ not the CMCJ thus treatment directed at the MCPJ
Treatment
· MCPJ synovectomy, collateral ligament reconstruction and adductor fascia release if tight
· if advanced then arthroplasty or arthrodesis
· Collateral ligament reconstruction
§ dorsal longitudinal incision
§ EPL and the adductor aponeurosis are reflected ulnarward
§ ulnar collateral lig is detached usually distally and the attenuated portion resected
§ synovectomy of the joint
§ ulnar collateral reattached with a pull out suture or bone anchor
TYPE II THUMB DEFORMITY
· rare
· combination of type I and type III
· MP flexion with IP hyperextension and associated subluxation or dislocation of the CMC
· Rx similar to type I and III
TYPE V THUMB DEFORMITY
· results from stretching of the MP volar plate
· MP hyperextension and IP flexion and tension increases in the flexor tendon
· different to the type III as the metacarpal does not assume the adducted position
· Rx is stabilization of the MP in flexion by a volar capsulodesis, sesamoidesis or fusion
ARTHRITIS MUTILANS
· aggressive and severe form
· marked skeletal collapse due to loss of bone substance
· usually all digits involved
· associated with psoriatic arthritis
· arthrodesis and synovectomy are the procedure of choice
· may require bone grafts if significant loss of bone stock to restore bone length and aid in fusion
OPERATIVE TECHNIQUES FOR THUMB RECONSTRUCTION
IP Joint
SYNOVECTOMY
dorsal incision either logitudinal, Y-shaped or zig-zag
can release portion of the extensor to gain access to the joint
midlateral incision gives access to the volar pouch after division of the ulnar accessory collateral
post op protect the joint with a K-wire for 10 days and then splint to reduce any extensor lag
IP JOINT RELEASE
moderated severe type I deformites
dorsal incision is critical as limited amount of skin
2 lateral incisions used by green
extensor tenolysis
dorsal capsulotomy by placing the blade under the extensor and rotating the blade 90 degrees and releasing from either side
Z-plasty is another option dorsally, usually cant close the wound completely
MP Joint
SYNOVECTOMY OF THE MP JOINT
· dorsal longitudinal incision
· incision inbetween EPL and EPB reflected ulnarly and radially respectively
· synovectomy and then the extensor mechaism is closed
· thumb splintted for 2 weeks
ARTHRODESIS
· problems with include marked deformity, bone loss and soft bone that does not allow internal fixation
· arthrodesis of the MP and IP principles
o dorsal approach
o synovectomy
o dislocate the joint, may need to release the accessory collateral
o remove all articular cartilage
o fuse the thumb IP in full extension with a degree of pronation
o MP fused in 15 degrees flexion, 15 degrees abduction, 15 degrees internal rotation
o if unstable CMC fuse MP joint in more flexion (eg 25 degrees)
o K-wires for IP
o k-wires, K-wires and tension band, 2 herbert screws for MP joint
o consider bone graft
ARTHRODESIS IN ARTHRITIS MUTILANS
· difficult due to the loss of bone stock
· use bone grafts to restore length and provide enough for fusion
· can use harrisions" peg or swanson implant and the joint K-wired to provide a fibrous union
TRAPEZIOMETACARPAL JOINT ARHTROPLASTY
· implant arthroplasty is rarely done
· more commonly a resectional arthroplasty
· resect part or all of the trapezium and the base of the 1st metacarpal then resuspend with a ligament and tendon interposition
· MCPJ hyperextension needs to be treated at time of CMCJ arthroplasty