Summary Isolated ulnar shaft fractures are rare fractures of the forearm caused by either direct blow to the forearm ("nightstick" fracture) or indirect trauma (fall). Diagnosis can be made primarily by physical exam and plain radiographs. Minimally displaced (< 50% displacement and < 10° of angulation) are often treated nonsurgically, while treatment has historically been surgical open reduction and internal fixation with compression plating for displaced fractures. Epidemiology Incidence rare < 1% of upper extremity fractures Demographics highest incidence in men between age 10 and 20 women over age of 60 Etiology Pathophysiology mechanism of injury direct trauma login to view 1 more bullet indirect trauma login to view 3 more bullets Associated conditions bisphosphonate-related seen as isolated, transverse proximal one-third ulnar fractures appear similar to the more commonly known atypical subtrochanteric fracture login to view 1 more bullet elbow and DRUJ injuries Monteggia fractures Essex-Lopresti injuries compartment syndrome evaluate compartment pressures if concern for compartment syndrome Anatomy Osteology axis of rotation of forearm runs through radial head (proximal) and ulna fovea (distal) distal radius effectively rotates around the distal ulna in prono-supination the ulna and radius form a functional unit; mal-angulation of ulna fractures can lead to limitation of forearm rotation Ligaments Interosseous membrane (IOM) occupies the space between the radius and ulna login to view 1 more bullet comprised of 5 ligaments login to view 5 more bullets Classification Descriptive closed versus open location comminuted, segmental, multi-fragmented displacement angulation rotational alignment OTA Classification OTA classification Type A Simple fracture Spiral (A1) Oblique (A2) Transverse (A3) Type B Wedge fracture Intact (B2) Fragmentary (B3) Type C Multifragmentary fracture Intact segmental (C2) Fragmentary (C3) Presentation Symptoms pain and swelling loss of forearm and hand function Physical exam inspection gross deformity open injuries check for tense forearm compartments neurovascular exam assess radial and ulnar pulses document median, radial, and ulnar nerve function provocative tests pain with passive stretch of fingers login to view 1 more bullet Imaging Radiographs recommended views AP and lateral views of the forearm additional views oblique forearm views for further fracture definition ipsilateral AP and lateral of the wrist and elbow login to view 2 more bullets Treatment Nonoperative cast or brace immobilization, soft compression dressing indications login to view 3 more bullets modality login to view 6 more bullets outcomes login to view 2 more bullets Operative external fixation indications login to view 1 more bullet ORIF indications login to view 3 more bullets outcomes login to view 1 more bullet ORIF with bone grafting indications login to view 2 more bullets outcomes login to view 1 more bullet technique login to view 9 more bullets IM nailing indications login to view 1 more bullet outcomes login to view 1 more bullet Techniques Cast or brace immobilization, soft compression dressing technique cast/brace may extend just above elbow to control forearm rotation, however, randomized studies have shown no difference in outcomes between above elbow and below elbow immobilization login to view 3 more bullets External fixation technique 2nd and 3rd metacarpal shaft can both be utilized for distal pin placement pin diameter should not exceed 4 mm ORIF approach subcutaneous approach to ulna shaft technique 3.5 mm DCP plate (AO technique) is standard login to view 1 more bullet compression mode preferred when the fracture allows to achieve anatomic primary bony healing login to view 1 more bullet locked plates are increasingly indicated over conventional plates in osteoporotic bone bridge plating may be used in extensively comminuted fractures interfragmentary lag screws (2.0 or 2.7 screws) if necessary open fractures login to view 1 more bullet postoperative care early ROM unless there is an injury to proximal or distal joint should be managed with a period of non-weight bearing due to risk of secondary displacement of the fracture login to view 1 more bullet ORIF with bone grafting technique bone graft options login to view 8 more bullets IM nailing approach inserted through the posterior olecranon technique may use a small incision at fracture site to facilitate passing of nail Complications Infection incidence 3% incidence with ORIF risk factors open fractures Compartment syndrome incidence up to 15% depending on mechanism and fracture characteristics risk factors high energy crush injury open fractures low velocity GSWs vascular injuries coagulopathies (DIC) Nonunion incidence < 5% after compression plating up to 12% in extensively comminuted fractures treated with bridge plating risk factors extensive comminution poorly applied plate fixation treatment atrophic nonunions can be treated with 3.5 mm plates and autogenous cancellous bone grafting Infection and atrophic nonunions can also be treated with the Masquelet technique Hypertrophic nonunions treated with debridement and compression plating Malunion risk factors direct correlation between restoration of radial bow and functional outcome Neurovascular injury risk factors PIN injury with Monteggia fxs Type III open fxs treatment observe for three months to see if nerve function returns login to view 1 more bullet Refracture incidence up to 10% with early hardware removal risk factors removing plate too early login to view 1 more bullet large plates (4.5 mm) comminuted fractures persistent radiographic lucency treatment wear functional forearm brace for 6 weeks and protect activity for 3 months after plate removal Prognosis For minimally displaced and angulated fractures (< 50% displacement and < 10° of angulation), nonoperative management has equivalent clinical outcomes to surgical treatment.