ULNOCARPAL ABUTMENT SYNDROME

Question 1

Foveal soft spot

Answer 1

Space bounded by:
- FCU tendon
- ECU tendon
- Ulnar styloid process
- Triquetrum
Foveal tenderness indicates:
- TFCC injury
- Ulnotriquetral ligament injury

Question 2

2 investigations for ulnocarpal abutment syndrome

Answer 2

1. Plain radiographs
   - PA wrist in 90-90 position with forearm in neutral rotation
   +/- pronated grip PA view
   +/- contralateral comparison view
   - look for sclerosis and cystic changes in the lunate and ulnar head
2. MRI = look for 3 things
   - Associated soft-tissue pathology = TFCC tears
   - Chondromalacia
   - Marrow oedema in lunate and ulnar head

Question 3

Surgical options for positive ulnar variance and ulnocarpal abutment syndrome

Answer 3

Joint preserving vs. joint sacrificing
Joint preserving = ulnar shortening osteotomy (most common procedure)
5 joint sacrificing options:
1. Wafer procedure
- involves arthroscopically removing 2-4mm of articular cartilage and bone under TFCC
2. Darrach procedure = ulnar head resection
3. Sauve-Kapandji procedure = DRUJ arthrodesis and distal ulna resection (creates a proximal pseudoarthrosis to allow forearm rotation)
4. Ulnar hemiresection arthroplasty
- involves removing the radial 1/2 of the ulnar head
- requires an intact/ functioning TFCC
5. Ulnar head replacement
- severe ulnocarpal arthritis
- salvage option with a failed Darrach procedure

Question 4

Ulnar shortening osteotomy:
3 indications
Technique

Answer 4

1. Indications
   - Positive ulnar variance
   - DRUJ incongruity
   - No ulnocarpal or DRUJ arthritis
2. Technique
   - Oblique diaphyseal osteotomy with plate fixation as a anti-glide construct
   - Often combined with arthroscopic TFCC repair

Question 5

Darrach procedure:
Advantages
Disadvantages
Indications
Contraindications
Technique

Answer 5

1. Advantages
   - technically easier
   - faster recovery = shorter immobilisation
2. Disadvantages = 4 main complications are
   - stump instability
   - radioulnar convergence
   - ulnocarpal translocation
   - weakness
3. Indications
   - elderly low-demand patients
   - ulnocarpal and DRUJ arthritis
   - RA patients without ulnocarpal translocation
4. Contraindications = high-demand patients
5. Technique
   - Subperiosteal exposure of the ulnar head
   - Ulnar osteotomy proximal to sigmoid notch (max 2cm)
   - Preservation of ulnar styloid and its attachments
   - Bevel end of stump to smooth bullet shape to prevent tendon attrition
   - Interposition of PQ between radius and stump to prevent radioulnar convergence
   - Volar capsulodesis to dorsal ulna to stabilise stump

Question 6

Sauve-Kapandji procedure:
Advantages
Disadvantages
Indications
Contraindications
Technique

Answer 6

1. Advantages
   - less stump instability
   - no radioulnar convergence
   - no ulnocarpal translocation
   - less weakness
2. Disadvantages
   - technically harder
   - slower recovery = 6wks immobilisation
   - complications = stump instability, nonunion
3. Indications
   - active high-demand patients
   - ulnocarpal and DRUJ arthritis
   - RA patients with ulnocarpal translocation
4. Contraindications = risk factors for nonunion
5. Technique
   - Dorsal approach through 5th extensor compartment
   - L-shaped capsulotomy to expose DRUJ
   - Pass 2x K-wires into ulnar head
   - Prepare DRUJ surfaces
   - Centre ulnar head in sigmoid notch
   - Advance wires across sigmoid notch into radius
   - Pass 2x cannulated screws over wires
   - Resect 10mm of ulna proximal to DRUJ

Question 7

Differentials for ulnar-sided wrist pain

Answer 7

Bony vs. soft-tissue
Bony causes:
1. Distal radius fracture
2. Distal ulna fracture
3. DRUJ injury
4. Essex-Lopresti injury
5. Triquetral/ pisiform/ hamate fracture
6. Kienbock's Disease
7. Ulnocarpal abutment
8. Ulnocarpal arthritis
9. LT arthritis
Soft-tissue causes:
1. FCU tendonitis
2. ECU tendonitis
3. TFCC injury
4. LT ligament injury
5. Ulnar nerve neuroma