Hand Bone

Thumb base and first CMC joint

First CMC osteoarthritis, ulnar collateral ligament injury, Bennett and Rolando fractures.

33 questions 3 source pages

Images appear with the first question taken from each source page — tap a question to open it.

Q1Describe the X-ray findings of first CMCJ osteoarthritis.▸

Joint space narrowing, subchondral sclerosis
Dorsal and radial subluxation >1/3, osteophytes
Also arthritis in the STTJ
MCPJ hyperextension deformity; narrowing of the 1st webspace
Eaton stage IV; request a Robert's view (hyperpronation, thumb flat on cassette)

Q2Describe the Eaton and Littler classification.▸

I: increased joint space
II: <1/3 subluxation, osteophyte <2mm
III: >1/3 subluxation, osteophyte >2mm
IV: pantrapezial arthritis

Q3What are the key examination findings and tests in first CMCJ OA?▸

Look: square off sign (dorsoradial prominence), MCPJ hyperextension, adducted and flexed 1st MC
Feel: tenderness, grind, crank, torque and retropulsion tests
Move: ROM, 1st webspace (45-55deg between 1st and 2nd MC), STT radiocarpal grinding test
Rule out Finkelstein, Eichhoff and RCJ grind; associations include carpal tunnel (50%) and trigger finger

Q4What is the conservative management of first CMCJ OA?▸

Lifestyle modification, splint, NSAIDs
Steroid injection: 80% pain relief in Eaton 1
Physio: 1st webspace stretching and 1st dorsal interosseous strengthening

Q5What are the operative options for first CMCJ OA by stage?▸

Early (stage 1-3): arthroscopic debridement + thermal shrinkage; first MC basal osteotomy
Later (stage III/IV): trapeziectomy +/- webspace contracture release, or Eaton's procedure (trapeziectomy + LRTI)
Newer: suspensionplasty with suture button, APL (Weilby) or ECRL; less commonly 1st CMCJ arthroplasty or fusion
Fusion contraindicated in stage IV (exacerbates STTJ arthritis); unable to put hand flat
Davis 2012 RCT and Cochrane 2015: no long-term benefit of LRTI over trapeziectomy alone; LRTI had more adverse events
MCPJ hyperextension: EPB transfer to PP base, volar capsulodesis, or MCPJ fusion

Q6Describe the pathoanatomy of first CMCJ osteoarthritis.▸

Biconcave saddle joint
Beak ligament (trapezium volar tubercle to ulnar 1st MC base) prevents dorsal subluxation on key pinch
Weakened beak ligament -> dorsal subluxation on pinch -> see-saw movement -> cartilage degeneration -> further instability
Recent evidence: dorso-radial ligament more important than beak ligament, maintaining the relationship between 1st and 2nd MC

Q7What history is important in first CMCJ OA?▸

Risk factors: occupation
Pain
Functional limitations

Q8What is the aim of treatment in first CMCJ OA?▸

Stable, painless thumb
Restore thumb function of opposition

Q9Describe the Wagner approach to trapeziectomy.▸

Incision between dorsal and volar glabrous skin
Interval between APL and thenar muscles (or scope)

Q10What are the advantages and disadvantages of trapeziectomy?▸

Advantages: simple procedure, good pain relief, preserves ROM
Disadvantages: splintage 4-6 weeks
Loss of thumb length and pinch strength (50-60%)
Metacarpal subsidence and instability

Q11What is the functional position for first CMCJ fusion and when is it contraindicated?▸

Radial and palmar abduction 30deg, 15deg pronation
Cons: unable to put the hand flat on the table
Contraindicated in stage IV - exacerbates STTJ arthritis

Q12Which nerves are targeted in first CMCJ denervation?▸

Thenar branch of the median nerve
Superficial branch of the radial nerve entering the CMCJ
Articular branches of the palmar cutaneous branch
Nerve of Cruveilhier
Dorsal articular nerve of the first dorsal interosseous space

Q13What is injured in gamekeeper's/skier's thumb and where do the avulsions occur?▸

Injury to the ulnar collateral ligament, important for lateral pinch
Avulsion distally 50%, proximally 40%, midsubstance 10%

Q14How do you differentiate partial from complete UCL injury?▸

Radial stress test at neutral and 30deg (neutral tests accessory + proper, 30deg tests proper)
Complete: 15deg more laxity compared with normal; at 30deg, no endpoint
Grade 1: pain, no laxity; grade 2: soft endpoint; grade 3: no endpoint
Also rule out a Stener lesion

Q15What is a Stener lesion and what is its mechanism?▸

Complete UCL rupture trapped superficial to the adductor pollicis aponeurosis
Prevents healing or causes unpredictable healing; fibrotic mass -> needs operative treatment
Mechanism: forced hyperabduction of the thumb

Q16What investigations are used for UCL injury?▸

XR: avulsion fracture
USG/MRI: Stener lesion

Q17How is incomplete versus complete UCL injury managed?▸

Incomplete: thumb spica cast 4 weeks, then splint 2 weeks, then gentle ROM; no strenuous exercise for 3 months
Complete acute: repair UCL +/- suture anchor or pullout wire, then repair aponeurosis to extensor tendon sheath, K wire with MCPJ at 20deg flexion, thumb spica
Chronic/Stener: static reconstruction with PL graft; dynamic reconstruction with EIP, EPB or adductor pollicis

Q18What is the outcome after UCL injury treatment?▸

Samora (CJSM 2013): >90% excellent outcome
Acute and chronic injuries achieved comparable results (acute = chronic)

Q19What is the difference between gamekeeper's and skier's thumb?▸

Gamekeeper's thumb = chronic injury (6 weeks)
Skier's thumb = acute injury

Q20Where does the adductor pollicis attach?▸

Ulnar base of the proximal phalanx of the thumb

Q21What are the key facts about 1st metacarpal fractures?▸

80% involve the MC base, most common is Bennett (partial intra-articular)
Others: Rolando (complete intra-articular +/- comminuted) and extra-articular
Mechanism is typically axial force to the thumb
CMCJ allows large sagittal movement; up to 30deg angulation is accepted

Q22Describe the X-ray findings in this hand injury.▸

1st MC base intra-articular fracture-subluxation
CMCJ radial and dorsal subluxation
1st MC is supinated, shortened, adducted and flexed

Q23How does the 1st metacarpal displace in a Bennett fracture?▸

Shortened with radial and dorsal subluxation by APL
Supination by EPL and adductor pollicis
Adduction by adductor pollicis

Q24What is a Bennett fracture and which X-ray view best shows displacement?▸

2-part volar ulnar intra-articular fracture of the 1st MC base
Known to be easy to reduce but difficult to hold
Hyperpronated thumb (Robert's) view best assesses displacement

Q25Why is surgery usually needed for a Bennett fracture?▸

Fracture is intra-articular, displaced with joint subluxation
Conservative treatment only for undisplaced fractures ie 1mm
Distal fragment is subjected to multiple tendon pull and prone to displacement

Q26What is the PAET reduction manoeuvre?▸

(1) Traction
(2) Extension with pressure over dorsal apex
(3) Abduction
(4) Pronation of the MC

Q27Is it necessary to fix the ulno-volar fragment in a Bennett fracture?▸

No - fixation is not necessary to catch the ulno-volar fragment

Q28How is CRPP performed for a Bennett fracture?▸

Indicated if small fragment and reducible
1st pin: distal fragment to trapezium
2nd pin: 1st to 2nd MC to maintain length
Followed by thumb spica cast immobilisation

Q29When is ORIF used for 1st MC base fractures and what implants are used?▸

If 1. large fragment, 2. irreducible
ORIF with K wire or screw
Lag screw for Bennett, plate for Rolando
Post op casting x 4/52

Q30Describe the Wagner approach for ORIF of the 1st MC base.▸

Skin incision between volar and dorsal radial skin, curving volar towards the radial border of FCR (hockey stick incision)
Plane between APL and thenar muscles (in plane radial and medial)
Protect sensory branches of radial nerve
Subperiosteal reflection of thenar muscle

Q31How is a Rolando fracture treated and what is its prognosis?▸

Base split into volar and dorsal fragment (Y fracture)
ORIF with plate (T/L plate) or external fixation with Thoren traction (abduction + extension vectors)
Connected in a Bandi outrigger splint for 2 weeks, then cast
Worse prognosis

Q32What is opposition of the thumb?▸

Palmar abduction, flexion and pronation

Q33What is a reverse Bennett fracture and what must you look for?▸

Reverse Bennett = fracture of the base of the 5th MC
CT to look for concomitant hamate fracture

This site is private

Thumb base and first CMC joint