Fractures of the Distal Ulna
Fractures of distal ulnar
1. Acute Ulnar Styloid Fractures
- The management based on the long-term effect that they may have on the stability of the distal radioulnar (DRU) joint.
- The relationship of the ulnar styloid to the stabilizing ligaments determines whether a specific fracture type is likely to result in DRU joint instability.
- The static stability of the DRU-joint is achieved by the bony congruity between the sigmoid notch of the radius and the ulnar head and the ligaments which hold the joint together.
- The ulno-radial ligament represents the transverse, peripheral part of the Triangular Fibro-Cartilage Complex (TFCC).
- The ligaments run from the fovea of the ulnar head and the base of the ulnar styloid to the dorsal and palmar edges of the sigmoid notch on the distal radius.
- The ulno-radial ligament is the major stabiliser of DRU-joint in the dorso/palmar direction.
Treatment of acute ulnar styloid fractures:
We emphasize that ulnar styloid fractures have to be assessed not solely as a bony fracture, but as a possible destabilizing injury to the ulno-radial ligament.
Ulnar styloid fracture irrespective of DRU joint instability
- Ulnar styloid fractures at its base with initial displacement more than 2 mm should be treated with open reduction and internal fixation.
- The fixation can be done with a single K-wire, tension band wiring, a wire loop/suture or screw fixation.
Instability of the DRU joint irrespective of the ulnar styloid fracture
- Whether or not there is an associated distal radial fracture, it is important to assess DRU-joint stability in order to decide whether the styloid needs reattaching or not.
- If the DRU-joint is unstable then either re-attach the ulnar styloid (which has the ulno-radial ligament attached to it or the ligament alone.
- Direct repair or reattachment of the ulno-radial ligament to the fovea of the ulnar head is required if the ulnar styloid fragment is too small or if DRU-joint instability is present without an ulnar fracture.
Immobilisation without fixation
- If the ulnar styloid fracture is undisplaced or reduces with reduction of the distal radius, as happens in most cases, patients can be treated with an above elbow cast for 6 weeks.
2. Symptomatic ulnar styloid fracture nonunion
Treatment of an ulnar styloid nonunion should be considered if patients are symptomatic and/or have DRU-joint instability.
- The ulnar styloid nonunion should be treated as a bony nonunion and be reattached to the ulnar head if the fragment is large.
- If the fragment is small, it should be shelled out and the ulno-radial ligament should be reattached directly to the fovea of the ulnar head.
- Patients treated in this way have been reported to have good to excellent results.
- If there is no DRU-joint instability the ulnar styloid can be shelled out without any associated ligament procedure.
- This can relieve localised pain without causing instability.
- It is then important to re-test the stability of the DRU-joint.
3. Ulnar head fractures
1. Head fracture alone
- Fractures that are displaced with an intra articular step or that are unstable are treated with open reduction and internal fixation with buried headless compression screws or Kirschner wires or with internal locked plates.
- Immobilisation after fixation depends on the stability of the fracture and its fixation.
2. Head fracture with extra articular component
- There are only three reported cases of ulnar head fractures with an extra-articular component found in our search.
- In one case the articular component was treated with a buried headless compression screw and the ulnar styloid fracture with tension band wires.
- Two cases were treated with an internal locked plate.
- Post-operative immobilisation was similar to fractures of the head alone and an excellent result was achieved in these cases.
Treatment of ulnar head fractures
- We cannot recommend operative fixation in all cases based on the current literature.
- It will, however, depend on the fracture pattern, displacement and stability and whether the physician can or would like to mobilise the patient early.
- We do recommend a Computer Tomography (CT) scan of the fracture to assess fragment sizes, displacement and suitability for primary fixation.
- In general, the method of fixation would depend on the fracture pattern.
- In intra articular fracture is best treated with a buried headless screw.
- If the extra-articular component extends towards the neck of the distal ulna a fixed angle device such as a condylar blade plate or an internal locking plate is recommended.
- Tension band wiring is recommended if the extra articular component involves the ulnar styloid.
3. Distal ulnar neck or distal shaft fractures
Treatment of distal neck or distal shaft fractures
- Isolated stable fractures, caused by a direct injury, or those that are stable once the radius has been reduced can then be treated with immobilisation in an above elbow cast.
- Irreducible or unstable fractures require open reduction and internal fixation.
- This can be achieved using either a blade plate, tension band wiring supplemented by intra-fragmentary screws or an internal locking plate.
4. Comminuted intra-articular distal ulnar fractures
Treatment of comminuted distal ulnar fractures
- The indications for using a salvage procedure as a first option are very limited.
- There is nothing in the literature to suggest that excising or replacing the ulnar head acutely has a benefit over waiting to assess the final result.
- We therefore recommend an initial approach of restoring and maintaining the overall alignment of the ulna and DRU-joint with the later option of a salvage procedure depending on the final result.