The management of distal ulnar fractures in adults: a review of the literature and recommendations for treatment

The management of acute ulnar styloid fractures is 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 [1‐3] (Fig. 1). The ulno-radial ligament represents the transverse, peripheral part of the Triangular Fibro-Cartilage Complex (TFCC) [1‐8]. 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 [4‐7, 9] (Fig. 1). The ulno-radial ligament is the major stabiliser of DRU-joint in the dorso/palmar direction [6, 10].

We found 5 prospective and 11 retrospective articles as well as two case reports that dealt with ulnar styloid fractures (Table 1). Ulnar styloid fractures seldom occur alone. More than 40% (range 21–61%) of distal radius fractures have an associated ulnar styloid fracture [11‐17] (This increases to 86% if the radial fracture is intra-articular [18]). If the ulnar styloid fracture is associated with a distal radius fracture, the ulnar styloid fracture will reduce with reduction of the distal radius in many cases [19] (Fig. 2). In such circumstances they can be treated with an above elbow cast for 6 weeks [20]. Obviously, exact restoration of the radius fracture around the sigmoid notch is of paramount importance for DRU-joint stability [21]. In a retrospective study of 71 ulnar styloid fractures in 130 patients with distal radial fractures, the wrists had significantly greater instability of the DRU-joint if the ulnar styloid fracture was >2 mm displaced initially [11] (Fig. 3). This was even more obvious if the fracture was at the base of the ulnar styloid [11] as there was likely to have been an associated detachment of the ulno-radial ligament (Fig. 1). This is important as 41% of all ulnar styloid fractures occur at its base [11] and contribute to a poorer outcome because of their effect on DRU-joint instability [22]. Fixation of ulnar styloid base fractures with a single wire has been shown to restore DRU-joint stability in a small case series (n = 6) [10]. Fractures through the tip of the styloid are likely to be stable [20] (Fig. 4) and do not require fixation as the ulno-radial ligament remains attached to the ulnar head at the base of the styloid.

There is contradictory information regarding the importance of ulnar styloid fractures. Some claim that distal radial fractures with an associated ulnar styloid fracture have been shown to have an increased DRU-joint instability than distal radius fractures without an ulnar styloid fracture [11]. Others have found no difference when comparing the overall functional results with or without an ulnar styloid fracture [23, 24]. There are two possible reasons for this: 1. The ulnar styloid fracture may be distal to the true stabilising insertion at the fovea and does not affect the stabilizing properties of the ulno-radial ligament. 2. It is possible to have a destabilizing tear of the ulno-radial ligament in the absence of ulnar styloid fractures [25]. This may explain why late instability has been found without ulnar styloid fractures or non-unions [26]. To complicate matters further Triangular Fibro-Cartilage complex (TFCC) injuries have been found when there is no ulnar styloid fracture [12, 25] and these do not necessarily translate to instability of the DRU-joint.

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. Based on the published literature to date acute ulnar styloid fractures can be managed in the following ways.

Ulnar styloid fractures at its base with initial displacement more than 2 mm should be treated with open reduction and internal fixation [11, 20]. In our view the decision to fix the ulnar styloid is increasingly justified if the ulnar styloid is displaced in a radial direction (detaching the ulno-radial ligament) than in axial, distal direction (detaching the ulno-triquetral collateral ligament). The fixation can be done with a single K-wire [10, 22], tension band wiring [20] (Fig. 5), a wire loop/suture [22] or screw fixation [27].

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 [10, 19, 20]. 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.

If the ulnar styloid fracture is undisplaced or reduces with reduction of the distal radius, as happens in most cases [19], patients can be treated with an above elbow cast for 6 weeks [20].

The incidence of ulnar styloid fracture nonunion is between 26% [15] and 63% [14]. Of these only around 14% of patients have ulnar sided wrist pain [17]. There are a number of reasons why a non-united ulnar styloid fracture can become symptomatic: It can be responsible for a non-functioning ulno-radial ligament (peripheral TFCC detachment) [27] (Fig. 6), cause impingement of the overlying ECU tendon [28], abut on the carpus [27, 29] (Fig. 7) or be an irritative loose body [27] (Fig. 8). A constant physical finding in these patients is an ulnar sided wrist pain worse with wrist use and loading in rotation, combined with tenderness over the ulnar styloid [27]. Patients with ulnar styloid fractures at the base that malunite in a displaced position or go on to nonunion may develop DRU-joint instability. Tsukazaki et al. [30] identified that most patients with DRU-joint instability had a nonunion of an ulnar styloid fracture (13 out of 17).

Functional outcome scores for patients with nonunion of an ulnar styloid fracture are no worse than those that have united [14]. It has also been found that ulnar styloid nonunion is not associated with DRU-joint instability [25]. This is most likely explained by the fact that the nonunions have not been assessed to represent a destabilizing ligament injury but only a bony nonunion. Given the anatomy there ought to be a difference between a nonunion at the base as opposed to a more distal nonunion. However, we have not found any scientific support for this assumption in the articles we have reviewed.

Treatment of an ulnar styloid nonunion should be considered if patients are symptomatic and/or have DRU-joint instability [27]. The ulnar styloid nonunion should be treated as a bony nonunion and be reattached to the ulnar head if the fragment is large [27], [28] (Fig. 9). 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 [27]. Patients treated in this way have been reported to have good to excellent results [27, 28]. If there is no DRU-joint instability the ulnar styloid can be shelled out without any associated ligament procedure [21, 27, 31]. This can relieve localised pain without causing instability [31]. It is then important to re-test the stability of the DRU-joint.

There are only some case reports in the literature [32‐35] to scientifically advice us what to do with ulnar head fractures (Table 1). Intra articular fractures of the ulnar head are often associated with fractures of the radius. They can also occur in isolation [32‐34]. For treatment purposes they can be classed as two types. 1. Head fracture alone, or 2. Head fracture with involvement of extra-articular parts of the distal ulna (including the styloid) (Fig. 10).

The literature on ulnar head fractures is sparse with only case reports for review [32‐35] (Table 1). As they are most often associated with distal radius fractures the pattern of the distal radius fracture will have a strong influence on the overall functional outcome [30]. If the radius fracture is intra-articular involving the DRU-joint the functional outcome may already be determined irrespective of the treatment of the ulnar head fracture. However, a stable anatomical fixation of the ulnar head fracture along with stable fixation of the distal radius (if associated) may allow earlier movement and achieve an overall improvement in the functional outcome.

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. An 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 (Fig. 11) or an internal locking plate [35] is recommended. Tension band wiring is recommended if the extra articular component involves the ulnar styloid.

Not many scientific conclusions can be made from the few reports that deal with distal ulnar neck of shaft fractures (Table 1). Many of the patients with distal ulnar fractures in association with distal radial fractures realign and are considered to be stable once the radius is reduced [36]. Displaced or comminuted distal ulnar neck or shaft fractures can disrupt the DRU-joint [37] and thus may affect the functional outcome with regards to movement and pain in this joint.

In our experience, most distal neck or shaft fractures are associated with a distal radius fracture unless there is a direct injury to the ulna. The ulnar fractures that do not reduce when the distal radius is reduced often tend to be very distal. It is therefore difficult to improve reduction by closed means. It is also difficult to immobilise unstable fractures with cast treatment alone as it is very difficult to effect a three point fixation, even in an above elbow cast.

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 [36]. Irreducible or unstable fractures require open reduction and internal fixation [36, 37]. This can be achieved using either a blade plate [36], tension band wiring supplemented by intra-fragmentary screws [37] or an internal locking plate [25]. These methods have been shown to be successful in a small number of retrospective case series.

Comminuted distal ulnar fractures have only been mentioned in the literature in a case report (n = 1) [38] and a retrospective study on 15 patients [39] (Table 1). Such a fracture is likely to give a poor outcome. In the case report a primary ulnar head prosthesis was used [38]. Postoperatively movement was started early and an excellent final range of movement was achieved [38]. Seitz and Raikin reviewed 15 consecutive distal radius fractures with comminuted head fragments where the ulna had been managed with head resection and soft tissue interposition [39]. At an average of 5.8 years follow up patients had gained 85% of wrist movement and 88.6% of average grip strength compared with the contralateral wrist.

The interpretation of outcome will always be difficult as the vast majority will have an associated complex distal radius fracture. With regard to the comminuted distal ulnar fracture the surgeon has two possible options.

The first option is to restore and maintain the overall alignment of the ulna and DRU-joint. This could be done with manipulation and above elbow cast immobilisation alone or alternatively by surgical means with temporary wiring or external fixation. A salvage procedure could then be considered at a later date depending on the outcome. The potential problems with this management are wrist stiffness and reduced forearm rotation that may not be corrected with a late salvage procedure.

The second option would be to consider a salvage procedure acutely using a primary distal ulnar head replacement as described above [38] or ulnar head resection and soft tissue interposition [39].

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.