An isolated fracture of the ulnar shaft is defined as a nightstick fracture. The injury derives its name from the idea that a suspect struck with a police nightstick would hold his forearm above his face in a defensive posture when struck with a police baton, resulting in a fracture to the ulna. While these fractures have historically been treated non-operatively, they were believed to display a high rate of nonunion, leading to increased scrutiny for appropriate management of such injuries.
As stated, the origin of the phrase "nightstick fractures" originates from injuries obtained from patients who were struck by a police truncheon in the forearm while protecting their head. More generally, these fractures are caused by any direct blow to the medial forearm, but can also be seen with excessive pronation or supination of the forearm.
There appears to be no increase in the incidence of nightstick fractures in men or women; however, one study did report a lower mean age of presentation (37 years) compared to women (52 years).
Nightstick fractures are characteristically acute injuries caused by some form of direct trauma to the forearm. Nightstick fractures are typically closed injuries, and patients present with obvious pain and lack of function in the affected extremity.
On physical examination, practitioners should begin with a thorough examination of the skin to rule out an open fracture, which would change the immediate management of this patient. A thorough examination of the elbow and wrist is crucial to identify an associated Monteggia fracture or injury to the wrist. Test the patient's range of motion at the elbow, palpating for any "clicks" or "clunks" at the site of the radial head. Similarly, perform a "shuck test" at the wrist to assess for weakness or instability at the distal radioulnar joint (DRUJ).
Radiography is the most important initial test to be performed in patients with suspected fractures. X-rays of the elbow with a perfect lateral is necessary to assess for appropriate alignment of the radial head to rule out a Monteggia fracture. X-rays of bilateral wrists are useful to assess the wrist joint, taking care to assess for ulnar positivity or negativity compared to the normal contralateral. Ensure that pronation and supination are equal bilaterally at the time of obtaining the radiograph, as pronation and supination effects ulnar positivity and negativity on radiographic views. CT scans are very rarely necessary, as any fracture not clearly elucidated on radiograph could be safely managed non-operatively. Thus, advanced imaging such as CT or MRI should only be used to rule out other suspected pathology.
Historically, closed non-displaced fractures with less than 50% of displacement could be treated non-operatively, given the low degree of surrounding periosteal and interosseous membrane damage associated with non-displaced fractures. Multiple studies support the early mobilization as an appropriate treatment for minimally displaced fractures due to the stabilizing effects of the radius and interosseous membrane, particularly in fractures that are mid-shaft or distal shaft. There does not appear to be a difference in outcomes with immobilization in either pronation or supination. Mid-prone positioning is appropriate and yields good results.
In contrast, proximal shaft fractures are more likely to require surgical intervention due to their association with radial head instability. Open isolated ulnar shaft fractures also require a formal surgical debridement with internal fixation, as is the standard of care for open fractures. More than 5 mm of displacement or shortening is an indication for surgical stabilization. Polytrauma patients are also more likely to benefit from surgical stabilization, as surgical intervention allows for easier utilization of the extremity sooner after injury.
Any patient who presents with an isolated fracture of the ulnar shaft should be carefully evaluated for concomitant injuries, such as a Monteggia fracture pattern where the radial head is no longer in continuity with the capitellum. Therefore it is imperative to obtain a perfect lateral x-ray of the elbow to ensure appropriate positioning of the radial head in relation to the capitellum. Monteggia fractures do require semi-urgent operative intervention, with the restoration of the length of the ulna being critical to achieving a stable reduction of the radial head.
Practitioners should also be aware of the risk of concomitant fractures and dislocations at the wrist when evaluating ulnar shaft fractures of any degree of displacement. Contralateral films are very useful in the evaluation of ulnar variance and distal radial/ulnar stability. Intraoperatively, compare fluoroscopic views of the wrist compared to contralateral with the same amount of pronation/supination before securing fixation to ensure appropriate ulnar length. One should routinely perform a "shuck test" on the wrist joint to test the stability of the DRUJ. If unstable, K-wires can provide temporary stabilization of the DRUJ, maximizing the long-term functional outcomes of the wrist.
There is little meaningful data to compare operative to non-operative treatment of isolated ulnar shaft fractures due to the differences in fracture severity and configuration between operative and non-operative management.
It does seem apparent, however, that for minimally displaced fractures with limited soft tissue damage, early mobilization results in a quicker time to union than prolonged immobilization or functional bracing. Excellent or good functional outcomes appears highest for the functional brace and early mobilization groups, with below elbow bracing being slightly superior to above elbow bracing.
In considering operative interventions, compression plating yields the best patient outcomes. Intramedullary nailing may be an acceptable alternative with the understanding that these patients were reported to have a poorer functional outcome in some studies.
Classically, nonunion is of greatest concern in the management of isolated fractures of the ulnar shaft; however, it appears that rates of nonunion may be lower than previously thought. For non-operatively managed fractures, one meta-analysis reports a nonunion rate ranging from 2% to 4%. In nightstick fractures that were managed surgically, the nonunion rate was 0% to 2% for fractures treated with plate fixation, while fractures treated with intramedullary fixation had a 5% rate of nonunion.
Isolated fractures of the ulnar shaft are most commonly a result of either a direct blow to the forearm or a hyperpronation or hyper-supination loading injury that occurs during a fall. Therefore the prevention of nightstick fractures is best centered around providing appropriate walking aids to those with impaired mobility or at increased risk of falls.
Patients who have sustained a nightstick fracture should seek counsel from a trained orthopedist with experience in the management of upper extremity fractures to obtain appropriate radiographs and rule out any concomitant injuries that may require further intervention.
Patients with isolated fractures of the ulnar shafts are most likely to be seen initially by their primary care provider or a mid-level practitioner. Such practitioners should have a low threshold for obtaining radiographs of the forearm with a reported history of trauma to the extremity and then referring to an orthopedic surgeon for further management. Nightstick fractures are almost always managed on an outpatient basis if the patient is not a polytrauma. Optimal patient outcomes are dependent on appropriate initial imaging at the time of initial evaluation, as well as appropriate follow-up with an orthopedic surgeon. If it is determined that the patient is a surgical candidate, it is important that the surgeon and all operating room personnel are comfortable with the relevant anatomy and surgical plan. Data from multiple sources and meta-analysis of retrospective studies were used for the purpose of this article. [Level 3]
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