Lunotriquetral Ligament Injury

Lunotriquetral injury is far more rare than scapholunate ligament injury.

Presentation

  • History
    • Distinguishing between a recent acute traumatic injury and a degenerative pathology is essential.
    • Is there a history of acute trauma? What was the mechanism? Are there any other injuries (e.g. elbow/forearm)
    • If nontraumatic, can the patient recall any previous historical injury?
    • Patients may report ulnar sided wrist pain.
    • This may be exacerbated when loading the wrist, especially in pronation i.e. gripping or using tools
    • Stiffness or crepitus when using wrist

 Examination

  • Look/feel
    • A wrist effusion may be present
  • Move
    • General assessment of hand function
  • Special tests
    • The “ballotment” test is done by holding the lunate and triquetrum between both thumbs and fingers and alternating between dorsal and volar translation, feeling for abnormal movement or clicking.
  • Neurovascular status
    • This is essential in acute traumatic cases. The motor and sensory function of the median, ulnar, and radial nerves must be assessed and documented, along with the vascular status.

 Investigation

  • If there is suspicion of an acute high energy injury to the wrist then the patient should be referred to the emergency department urgently.
  • Bloods
    • Typically not required
  • Imaging
    • PA radiograph of the wrist
      • First line imaging modality.
      • Examine for disruption of Gilula’s lines (fig xxx). A break in these lines may indicate an abnormality within the carpus
      • Examine for the presence of carpal fractures or widening of distance between lunate and triquetrum of more than 2mm
    • Lateral radiograph of the wrist
      • First line imaging modality
      • Measure the scapholunate angle, an angle <30 degrees suggests a VISI deformity
    • MRI scan
      • Typically ordered from tertiary care to confirm diagnosis

Differentials

  • Scapholunate ligament injury (DISI)
  • Perilunate
  • Perilunate dislocation or fracture dislocation

Red Flags:

Acute neurovascular deficit in an acute injury mandates emergent referral
Severe diffuse swelling in a chronic setting could be an indication of underlying inflammatory arthropathy.

Management

The management depends on whether the injury is acute or chronic. All acute injuries should be referred either via the emergency department or via urgent referral to the local tertiary hand and wrist clinic.

Conservative

● Acute, undisplaced sprains can be treated with a period of immobilisation, careful clinical follow-up, and physiotherapy.

● Nonsurgical treatment is also an appropriate first line treatment in chronic degenerative situations which are minimally symptomatic in low demand patients. In these circumstances, NSAIDs when tolerated and physiotherapy are indicated.

Operative

● Acute ruptures with displacement or instability, chronic but reducible ruptures, or ongoing significant pain that has failed nonsurgical treatment can be considered for surgical intervention.

Prognosis/Managing Expectations

The prognosis is multifactorial and depends on the nature of the condition, the nature of the injury, and the patients functional status

Figure 2. A: A longitudinal incision is made in line with the 3rd
metacarpal ray over the carpus, avoiding the SBRN (sensory branch
of the radial nerve) and the DSBUN (dorsal sensory branch of the
ulnar nerve). B: Ulnar flaps of the extensor retinaculum are created
by dividing the septa which separate the 3rd through the 5th
extensor compartments. EPL; extensor pollicis longus; EI; extensor
indicis ; ED; extensor digitorum.

Figure 3. A: The dorsal radiocarpal and intercarpal ligaments are
identified and a ligament splitting capsulotomy is made (Berger’s
Flap). DST Dorsal scaphotriquetral ligament; DRT: Dorsal
radiotriquetral ligament. B: The dorsal component of the LT ligament
must be inspected to determine if suitable to repair, as well as the
articular surfaces of the midcarpal and radiocarpal joints.

Figure 4. A 2-0 fiberwire is used to repair the LT stump. The fiberwire
and size 1.3 mm Suture Tape are loaded into a 2.5mm push-lock
anchor which is inserted into the Triquetrum. The Suture Tape is
loaded into a second 2.5mm push-lock anchor and inserted into the
lunate, creating an augmented internal brace repair (see right).