Wrist

and Steven Maschke⁴

(3)

Department of Orthopedic Surgery, University of Wisconsin, Madison, Wisconsin, USA

(4)

Cleveland Clinic, Department of Orthopedic Surgery, Abu Dhabi, UAE

Take-Home Message

Potential spaces in the hand communicate and may transmit infection across the hand.
Wrist arthrosis is treated with motion-preserving procedures such as PRC or limited to complete wrist fusion. Limited fusions necessitate articulating surfaces on non-fused bones to be intact, i.e., no radiolunate arthrosis with capitolunate fusion.
The TFCC stabilizes the DRUJ and is vascularized in its peripheral 1/3. Tears destabilizing the DRUJ and in the vascularized portion warrant repair.
SL ligament tears and scaphoid nonunions result in predictable patterns of arthrosis managed similarly with motion-preserving procedures vs. fusions.

Definition

Dorsal compartments: 6 extensor compartments
- APL, EPB
- ECRL, ECRB
- EPL
- EDC, EIP
- EDM
- ECU
Bursas of the hand
- Radial bursa: thumb MCP joint to the proximal edge of the TCL (transverse carpal ligament)
  
  Deep to FDP at the wrist
- Ulnar bursa: small finger MCP joint to proximal edge of TCL
  
  Deep to FDP at the wrist
Spaces of the hand
- Deep:
  
  Parona’s space: potential space between PQ fascia and FDP tendons where radial and ulnar bursa communicate
  
  Infections may track from ulnar to radial bursa via this space
  
  Thenar: bound by thenar musculature radially and a vertical septum originating from the third MC ulnarly
  
  Midpalmar: bound radially by the third MC septum described above and ulnarly by hypothenar septum
  
  Hypothenar: located between hypothenar septum and hypothenar musculature
  
  Thenar, midpalmar, and hypothenar spaces bound distally by web
- Superficial:
  
  Interdigital space: loose connective tissue between fingers (web)
  
  Subaponeurotic space: between extensor tendons and metacarpal periosteum dorsally
  
  Subcutaneous: soft connective tissue on hand dorsum
Dorsal compartment tendinopathy:
- De Quervain’s: first dorsal compartment tendinopathy
- Intersection syndrome: second dorsal compartment tendinopathy
Patterns of arthrosis:
- SNAC: scaphoid nonunion advanced collapse
  
  Arthrosis due to progression of altered kinematics and wrist loading from scaphoid nonunion
- SLAC: scapholunate advanced collapse
  
  Arthrosis due to progression of altered kinematics and wrist loading due to scapholunate dissociation
Kienbock disease:
- Lunate necrosis and fragmentation
DRUJ: distal radioulnar joint
TFCC: triangular fibrocartilage complex
- Stability implied by articular congruity and TFCC
- Composed of volar and dorsal radioulnar ligaments, articular disc, ulnocarpal ligaments, and ECU subsheath
- Stabilizes DRUJ and function in ulnocarpal load transmission
- Deep attachment on fovea at ulnar styloid base

Etiology

Infection: penetrating injury, extension of infection from flexor tendon synovitis
De Quervain’s: new lactating mothers. Repeated thumb abduction and ulnar deviation. Anatomic anomaly of separate EPB compartment.
Intersection syndrome: common in rowers and weight lifters
Kienbock’s: likely multifactorial
DRUJ:
- Fall on extended pronated hand often associated with distal radius fractures
- Fractures within 7.5 cm of distal radius articular surface at high risk of DRUJ injury

Pathophysiology

Collar button abscess: forms volar and dorsal in the interdigital space
- Abducted finger posture differentiates this from a dorsal or volar subcutaneous abscess.
- May begin with a break in web skin.
- Tight volar skin causes dorsal tracking and prominence of infection.
Parona’s space: typically a continuation of radial or ulnar bursa infection
Thenar space:
- Posture of thumb abduction
- Difficulty with thumb range of motion
- Most common deep space infection
Midpalmar space:
- Midpalmar fullness and loss of concavity
- Flexed posture of digits
De Quervain’s:
- Inflammation within the first dorsal compartment due to overuse or anatomic anomaly of separate APL and EPB compartments
- Presents and swelling and tenderness adjacent to the radial styloid
- Pain with thumb flexion and ulnar deviation (Finkelstein’s test)
Intersection syndrome:
- Inflammation within second dorsal compartment
- Edema and tenderness is 4–5 cm proximal to the radial styloid in contrast to De Quervain’s
Instability:
- DISI: scapholunate dissociation leads to lunate extension which characterizes the deformity.
- VISI: lunotriquetral dissociation leads to lunate flexion.
- Static change in posture of the lunate requires LT or SL ligament disruption as well as loss of secondary stabilizers.
Scaphoid
- Scaphoid has retrograde blood supply increasingly disrupted with more proximal fractures.
- Unstable fractures (proximal pole, displaced, angulated, comminuted) require fixation.
- Nonunion leads to progressive arthrosis (SNAC wrist).
Kienbock disease:
- Presumed avascular necrosis due to multiple factors.
- Ulnar variance is not definitively a factor in disease development.
TFCC:
- Vascular supply present in periphery and absent centrally.
- Functional TFCC tear may result due to ulnar styloid base fracture.
- Ulnar styloid tip fracture leaves TFCC intact and does not require fixation.
SLAC:
- Scapholunate ligament injury → progressive diastasis, flexion of the scaphoid and extension of the lunate → progressive arthrosis

Imaging

Infection:
- Hand and wrist radiographs to rule out osteomyelitis or foreign body
- MRI and US to determine extent and depth of involvement
Instability:
- DISI:
  
  SL angle > 60° on lateral X-ray
  
  Scaphoid ring sign on AP
- VISI:
  
  SL angle < 30°
  
  Lunate flexion
Kienbock disease:
- X-ray: lunate sclerosis, fracture lines, disintegration, and collapse in later stages
- MRI: decreased signal on T1 imaging
- CT: demonstrates fracture lines and bony architecture
TFCC:
- MR arthrogram: dye extravasation to the DRUJ
DRUJ:
- True lateral X-ray: demonstrates subluxation
- Pronation, supination, and neutral CT: can be done with both wrists to demonstrate DRUJ incongruity