arthritis of base of thumb

definition

· degenerative arthritis at trapeziometacarpal joint

epidemiology

· commonest hand joint involved in OA

· most common in older women

· 90% are females > 50 yrs

· asymptomatic degenerative changes common

· associated with arthritis in scapho-trapezial joint in 50%

aetiology

Primary

· combination of

· high compressive loads

· relatively unstable joint

· complex range of movement

Secondary

· gout

· rheumatoid arthritis

· infection

· trauma

classification

· stage 1

· joint normal with synovitis

· stage 2

· joint space narrowed

· may be mild subluxation (< 1/3)

· stage 3

· joint space obliterated

· may be moderate subluxation (> 1/3)

· stage 4

· involvement of multiple joint surfaces

· esp. scapho-trapezial

clinical features

History

· pain at base of thumb

· esp. with pinch grip

· becomes constant

· difficulties with ADL

· stiff thumb

· weak pinch grip

Examination

· tenderness around TMC jt

· may be swelling from

· synovitis

· osteophytes

· positive grind test

· passive thumb circumduction and axial loading

· causes pain

· may be deformity

· fixed flexion-adduction contracture of 1st MC

· compensatory MCP jt extension

radiology

· trapezio-metacarpal joint

· loss of joint space and sclerosis

· osteophyte formation

· radial subluxation of MC base

· scapho-trapezial joint

· degenerative changes

differential diagnosis

· de Quervain’s tenovaginitis

· carpal tunnel syndrome

· scaphoid nonunion

· FCR synovitis

· volar ganglion

treatment

General

· majority of patients do not require treatment

Stage 1

· usually nonoperative

· may use soft tissue stabilisation

Stage II

· usually nonoperative

· may use arthrodesis

Stage III & IV

· tendon interposition arthroplasty

· silicone interposition arthroplasty

· suspensionplasty

Nonoperative

· rest

· activity alteration

· static splinting

· drugs

· oral analgesics and NSAIDs

· intra-articular steroids

Operative

Soft tissue stabilisation

Indications

· stage 1 disease not responsive to nonoperative treatment

Technique

· tendon used through MC base and trapezium to create stabilising ligament (tenodesis)

· can use

· palmaris longus

· FCR

Arthrodesis

Indications

· stage II and III disease

· usually reserved for young manual workers

· also useful for ligamentous laxity and neurological conditions

Contraindications

· pantrapezial OA

Advantages

· pain-free

· strong pinch

· allows heavy use

Disadvantages

· increases stress on adjacent joints

· limits mobility of thumb MC

· prolonged immobilisation

Position

· that assumed when fist made

· 30-40^o palmar abduction

· 10-15^o radial abduction

Excisional arthroplasty

Indications

· stage II & III disease

Advantages

· simple procedure

· minimal immobilisation

Disadvantages

· shortening of thumb ray

· weakness of pinch

· thumb adduction

Technique

· can maintain stability by shortening APL tendon

Tendon interposition arthroplasty

· consists of

· excision of trapezium

· interposition arthroplasty

· usually includes ligamentous reconstruction

· ligamentous suspension of base of 1st MC

· can use FCR or APL

· procedure then called suspensionplasty

Indications

· stage III and IV disease

· procedure of choice for most cases

Contraindications

· relative in rheumatoid arthritis

· osteoporosis and ligamentous laxity

Advantages

· relieves pain

· preserves movement

· maintains strength

· minimal immobilisation

· avoids silicone problems

Disadvantages

· if reconstruction omitted

· mild weaknes

· risk of proximal MC migration

Technique (FCR tendon)

· make dorsoradial incision

· along line of 1st MC in hand

· extend medially to palm

· small dorsal limb to expose radial artery

· dissect carefully

· to avoid radial nerve

· to avoid radial artery (directly over scaphotrapezial joint)

· open capsule over trapezium

· elevate thenar muscles from trapezium and 1st MC

· excise base of thumb MC with power saw

· to keep insertion of APL intact

· excise trapezium

· remove bone piecemeal

· take care not to damage underlying FCR

· make hole in base of MC

· perpendicular to plane of thumbnail

· from radial cortex to base

· position MC base medially in abduction

· harvest FCR tendon

· through longitudinal or series of transverse incisions

· split tendon longitudinally to insertion on MC II

· detach 10-12 cm strip proximally

· suspend MC base

· pass free end of FCR through hole in base and out radial hole

· suture it to the soft tissues on the MC and then to itself

· thus resurface MC base

· make spacer

· put longidudinal weaving suture in FCR remnant

· anchovy tendon on itself

· insert it into trapezium fossa

· tenodese EPB tendon to shaft of MC

· proximal to MCP jt

· stabilise MCP jt if > 30^o valgus instability or hyperextension

· arthrodesis

· capsulodesis

· close wound and apply thumb spica

· postoperative

· ROS and K wire at 10 days

· splint for another 3 weeks

· progressive exercises

Results

· > 90% satisfactory results long-term

Silicone replacement arthroplasty

Indications

· stage III and IV disease

· low-demand patient, esp. rheumatoid

Advantages

· retains movement at TMC jt

Disadvantages

· subluxation or dislocation from scaphoid

· prosthesis breakage (50% at 4 yrs)

· silicone synovitis

· subluxation can be addressed by soft tissue reconstruction

· strip of APL can be passed through hole in prosthesis

· problems with silicone difficult to address because it performs poorly in compression

Technique

· Swanson silicone prosthesis

· stem inserted into 1st MC

· spacer in gap left by trapezium excision

· functional elongation of 1st MC