Indications

Displaced or potentially unstable ulnar head fractures require accurate reduction and stabilization. These injuries should be recognized early and treated, ideally, within 7 days of injury.

Standard radiographs will provide most of the information about the fracture pattern (Fig. 28-5). Computed tomography (CT) may be necessary on occasion to fully evaluate the injury.

FIGURE 28-5 Plain radiograph clearly outlines articular fracture pattern.

The advent of angularly stable small locking plates allows patients of all ages to be considered for internal fixation, irrespective of their bone quality.

Contraindications

There are no absolute contraindications to internal fixation of displaced ulnar head fractures except the multifragmentary injury pattern that is rendered unable to be reconstructed by virtue of fragment size.

Surgical Technique

General or regional anesthesia is required. Contrary to previous reports,⁶ regional anesthesia is a safe and comfortable technique that can allow treatment on an outpatient basis.

The affected arm is placed on an arm table. The tip of the ulnar styloid is easier to expose when the forearm is placed in pronation. For this reason, the surgeon may choose to sit at the cranial edge of the arm table. If a distal radius fracture coexists, the surgeon will most likely choose to sit at the caudal edge of the arm table. It is therefore essential that the operating equipment (including mini-C-arm intensifier) is arranged in such a way that surgeon and assistant can move freely around the arm table during surgery.

An upper arm tourniquet is applied. The limb should be prepared and draped to the level of the tourniquet cuff. Intravenous prophylactic antibiotics are recommended immediately preoperatively.

A straight longitudinal incision along the course of the subcutaneous distal ulna is recommended. The dorsal sensory branch of the ulnar nerve lies immediately underneath the skin at the level of the ulnar neck. Extreme care must be taken to avoid this structure in the initial surgical approach.

The approach is deepened ulnar to the sixth extensor compartment to enable the stabilizing implant to be applied on the surface of the distal ulna between the tendons of the flexor carpi ulnaris and extensor carpi ulnaris. It is unusual to need to visualize the articular fragments directly, but in these rare instances a second approach can be made using the same skin incision but passing through the floor of the fifth extensor compartment. Retraction of the tendon of the extensor digiti minimi will allow direct inspection of any articular fragments.

Reduction of the fracture fragments is best performed indirectly using a small angularly stable implant. If reduction is attempted using pointed reduction forceps, the thin cortical bone of the ulnar head often fragments under load, leading to further comminution and possible failure.

The implant is best placed on the medial border of the ulna directly in line with the ulnar styloid. This acts as a buttress for the distal radius to be reduced onto (Fig. 28-6), in this case utilizing a specially designed implant for treating distal ulnar fractures.

FIGURE 28-6 Use of a specially designed low-profile locking plate for a distal ulnar fracture.

Clinical testing of DRUJ stability will reveal if a coexistent unstable TFCC tear is present.

An above elbow cast or sugar tong splint is applied with the elbow flexed to 90 degrees and the forearm in neutral rotation. Early movement is begun depending on stability of fixation.

The skin overlying the distal ulna is thin. As a result, implants placed here are frequently palpable—and may give rise to discomfort. A low threshold for implant removal, once union is certain, is recommended.

Clinical Examples

Case 1

A 77-year-old woman presented after a fall with a painful and deformed wrist. The initial radiographs reveal a displaced articular fracture of the distal radius and a minimally displaced long oblique extra-articular fracture of the distal ulna (Fig. 28-7A, B). Initial treatment consisted of the application of a bridging external fixator. The surgeon clearly concentrated on the reduction of the distal radius fracture, but—in the absence of an intact ulnar buttress—displacement of the unstable ulnar fracture was inevitable (see Fig. 28-7C, D).

FIGURE 28-7 Case 1. A and B, Fractures of both distal radius and ulna. C and D, After application of a bridging external fixator to the distal radius only. E, After ORIF of both bones with angularly stable implants.

Attempts were then made to provide an ulnar buttress by stabilizing the distal ulnar fragment with a longitudinal Kirschner wire (K-wire). This method provided insufficient stability, and it was not possible to maintain a reduction.

Stabilization by open reduction and internal fixation (ORIF) using a 2.0-mm mini-condylar plate (Synthes) (see Fig. 28-7E) and a volar distal radius plate (Synthes) allowed early movement and an almost complete recovery of function 3 months after surgery.

Had the necessity for the distal ulna to act as a weight-bearing buttress been appreciated at an early stage, the ulnar fracture could have been treated by a much simpler method of stabilization such as multiple lag screws. An example of this method of treatment for a similar fracture is shown in Figure 28-8.

FIGURE 28-8 A and B, Ulnar fracture treated with two lag screws. C, Operative view.

Case 2

A 20-year-old man was involved in a motor vehicle accident, sustaining multiple life-threatening injuries. His initial treatment concentrated on his major visceral trauma and unstable pelvic fracture. He sustained a displaced fracture of the distal radius and ulna (Fig. 28-9A, B) that was managed initially by a bridging external fixator (see Fig. 28-9C, D).

FIGURE 28-9 Case 2. A and B, Extra-articular fracture of distal radius with associated palmarly displaced ulnar head fracture. C and D, After initial stabilization with bridging external fixator to the distal radius only. E, After ORIF to stabilize both bones using angularly stable implants.

It was recognized 4 weeks after injury that the distal ulnar fracture had never been reduced and that the ulnar head lay in a palmar position.

ORIF of both fractures using a 2.0-mm mini-condylar plate (Synthes) and a dorsal distal radius plate (Synthes) (see Fig. 28-9E) allowed immediate rehabilitation and a return to full function.

The immediate requirement to treat life-threatening injuries resulted in early basic stabilization of the wrist fracture. Referral for definitive treatment of the radius and ulna fractures was delayed, although accurate anatomical stabilization was still possible. There had been no early attempt to reduce the distal ulna fracture, and this led to greater technical difficulty at the time of surgery.

Results

Reports of treatment of these unusual fractures are rare.

In 2004, we reported our series of 24 distal ulna fractures, associated with fractures of the distal radius, stabilized with a mini-condylar plate (Synthes).⁴ The majority of cases (83%) were comminuted neck fractures. In a small number of isolated ulnar head fractures, simple lag screws were also used. An average range of rotation of 146 degrees (76 degrees of pronation, 70 degrees of supination) was achieved at an average of 26 months after surgery. The average flexion/extension arc was 102 degrees (50 degrees flexion, 52 degrees extension). Nonunion of the distal ulna was seen in only one case and was treated by revision grafting and plating and went on to uneventful union.

Incidence

All authors agree that more than 50% of distal radial fractures are accompanied by fractures of the ulnar styloid. In a study of 130 distal radius fractures,⁷ 71 were noted to have a coexistent ulnar styloid fracture (55%). Of these, 39% involved the base (Fig. 28-11).

FIGURE 28-11 Incidence of site of ulnar styloid fractures.

Radiographic Prediction of DRUJ Instability

Instability of the DRUJ complicates a reported 3% to 37% of distal radius fractures,^8,9 yet fewer than 10% of distal radius fractures demand a surgical procedure on the distal ulna.^7,10 Instability relates to detachment of a significant portion of the TFCC—significant in either size or location. These situations arise either by a direct tear through a critical amount of the soft tissue component or by fracture through its bony anchorage.

Nakamura and colleagues¹¹ assessed the relevance of each of the four levels of ulnar styloid fracture on DRUJ stability in 10 cadaveric wrists and found no instability in styloid tip or midportion fractures but up to a 20% loss of stiffness (stability) in basal horizontal fractures. Basal oblique fractures, however, produced up to 70% loss of stiffness.

Wide displacement of any type of ulnar styloid fracture was also recognized as a significant risk for development of DRUJ instability—presumably because wide displacement would not be possible without a significant soft tissue tear (Fig. 28-12).

FIGURE 28-12 A and B, Radiographs at time of injury reveal true nature of styloid fragment displacement, which is not appreciated after reduction.

Indications

Ulnar styloid fractures only ever require stabilization when they are the cause (either partly or wholly) of DRUJ instability.

Assessment of DRUJ stability will therefore allow the surgeon to select which individual fractures require active treatment. Stability can only be assessed in the presence of an intact or stable reconstructed distal radius. In a wrist injury involving fractures to both distal radius and ulna, stable reconstruction of the radius must be achieved before judging DRUJ stability.

Passive anteroposterior glide of the distal ulna relative to the distal radius in positions of neutral rotation, full pronation, and full supination will provide this information. Assessment of the uninjured limb will give a guide to the normal laxity of the joint for any given individual.

If stabilization is deemed necessary, a choice of techniques is available. The fracture configuration will partly dictate the choices available. Fracture fragments of significant size (oblique and horizontal basal fractures) are suitable for bony reconstruction. More distal or comminuted fragments are suitable for reconstruction by soft tissue reattachment—ignoring the fracture fragments.

Contraindications

There are no contraindications to stabilization of the DRUJ. As noted earlier, small or comminuted fragments may preclude bony reconstruction, but soft tissue stabilization (by TFCC reattachment) should still be performed.

Surgical Technique

The surgical approach is identical to that described for stabilization of ulnar head fractures. However, the distal ulnar shaft need not routinely be exposed.

Soft tissue reattachment of the TFCC is not discussed in this chapter.

A number of different bony reconstruction techniques can be used.

Clinical Examples

Case 3

A 35-year-old man was involved in a motor vehicle accident in which he was thrown from his vehicle. He sustained an open injury to the ulnar side of his right wrist (Fig. 28-13A). After appropriate wound débridement, the displaced ulnar styloid basal oblique fracture was reduced and secured with a single 1.5-mm lag screw (see Fig. 28-13B). After reconstruction of the soft tissue defect with a lateral arm free flap, the skeletal stability allowed early rehabilitation and return to full function.

FIGURE 28-13 Case 3. A, Basal oblique fracture of the ulnar styloid. B, After internal fixation by single lag screw.

This fragment was of sufficient size to accept a gliding hole drill diameter of 1.5 mm. Central placement of the drill hole reduced the risk of fragmentation.

Case 4

A 23-year-old male professional rugby player complained of pain and “clunking” in his wrist on impact after an injury sustained during play. Plain radiographs revealed a displaced basal oblique fracture of the ulnar styloid (Fig. 28-14A). There was a suspicion that this was not a totally new injury and that a fibrous union of a previous fracture had been disrupted. Perifracture sclerosis was seen, suggesting a mature injury. The fracture was opened as described earlier and the fracture surfaces débrided to healthy cancellous bone. A tension band wiring was performed to stabilize the DRUJ and prevent further instability and “clunking” (see Fig. 28-14B, C), allowing a stable normal active range of motion.

FIGURE 28-14 Case 4. A, Displaced basal oblique fracture of the ulnar styloid. B and C, Tension band wiring.

The maturity of this injury and the need for débridement of the fracture surfaces meant that an accurate anatomical reduction with fragment interdigitation was not possible. Tension band wiring was selected as a technique more likely to provide a greater area of compression across the fracture site.

An alternative method of securing the tension band wire loop is shown (Fig. 28-15). This technique should be used with caution in the distal ulna because of the often uncomfortable prominence of the screw head through the skin.

FIGURE 28-15 Alternative configuration of tension band wiring.

Results

It remains the case that the presence of an ulnar styloid fracture represents a poor prognostic sign in wrist injuries.^13–17 The natural progression of this idea is to recommend regular operative stabilization of these injuries,¹⁸ but this approach fails to differentiate between different styloid fracture patterns.

In contrast to an interventional approach, Tsukazaki and coworkers¹⁹ examined 83 distal radius fractures to assess prognostic factors. In keeping with other descriptions on incidence, 44 cases (53%) had evidence of ulnar styloid injury. Again, no information was provided on the exact fracture configurations, yet only 19 fractures (43%) showed radiological evidence of union. There was no correlation between functional outcome, residual pain, and the presence or absence of an ulnar styloid fracture or nonunion. It is likely that the vast majority of these injuries were stable injuries of the DRUJ.

Few studies comment on the effects of fixation of ulnar styloid fractures.²⁰ No correlation between TFCC stabilization and outcome was found in a heterogenous group of Colles’ fractures. Since these studies were published, the accuracy of classification has improved enormously. We now accept that the exact fracture configuration in both the radial and ulnar sides of each injury is the critical determinant in stability and, therefore, outcome.

Nonunion

As previously stated, there seems to be no correlation between ulnar styloid nonunion and functional outcome. Fractures of the tip of the ulnar styloid frequently fail to unite but appear to be less of a clinical problem because they are unlikely to be associated with instability¹⁷ (Fig. 28-16).

FIGURE 28-16 Avulsion of tip of ulnar styloid.

Ulnar styloid nonunion has been classified²¹ into type 1 (with a stable DRUJ) and type 2 (with an unstable DRUJ). Those patients with symptomatic type 1 nonunion respond well to simple excision of the ununited fragment, whereas those patients with symptomatic type 2 nonunion require formal reconstruction and TFCC reattachment.