Summary Subtrochanteric fractures are proximal femur fractures located within 5 cm of the lesser trochanter that may occur in low energy (elderly) or high energy (young patients) mechanisms. Diagnosis is made with orthogonal radiographs of the hip in patients that present with inability to bear weight. Treatment is generally operative with cephalomedullary nail fixation. Epidemiology Incidence common 7 to 34% of femur fractures Etiology Pathophysiology young patients high-energy mechanism (MVC) elderly patients low-energy mechanism (ground level falls) rule out pathologic or atypical femur fracture denosumab or bisphosphonate use, particularly alendronate, can be risk factor Pathoanatomy deforming forces on the proximal fragment are abduction login to view 1 more bullet flexion login to view 1 more bullet external rotation login to view 1 more bullet deforming forces on distal fragment adduction & shortening login to view 1 more bullet Anatomy Biomechanics weight bearing leads to net compressive forces on medial cortex and tensile forces on lateral cortex Classification Russel-Taylor classification Historically used to differentiate between fractures that would amenable to an intramedullary nail (type I) and those that required some form of a lateral fixed angle device (type II) Current interlocking options with both trochanteric and piriformis entry nails allow for treatment of type II fractures with intramedullary implants Russel-Taylor Classification Type I No extension into piriformis fossa Type II Extension into greater trochanter with involvement of piriformis fossa Look on lateral xray to identify piriformis fossa extension AO/OTA classification AO/OTA Classification Examples 32-A3.1 Simple (A), Transverse (3), Subtrochanteric fracture (0.1) 32-B3.1 Wedge (B), Fragmented (3), Subtrochanteric fracture (0.1) 32-C1.1 Complex (C), Spiral (1), Subtrochanteric fracture (0.1) ASBMR Task Force Case Definition of Atypical Femur Fractures (AFFs), Revised criteria ASBMR Task Force Case Definition of Atypical Femur Fractures (AFFs), Revised criteria Four of five major features should be present to designate a fracture as atypical; minor features may or may not be present in individual cases Major criteria Associated with no trauma or minimal trauma, as in a fall from a standing height or less Fracture originates at the lateral cortex and is substantially transverse in its orientation, although it may become oblique as it crosses the medial femur Noncomminuted Complete fractures extend through both cortices and may be associated with a medial spike; incomplete fractures involve only the lateral cortex Localized periosteal or endosteal thickening of the lateral cortex is present at the fracture site Minor criteria Generalized increase in cortical thickness of the femoral diaphyses Prodromal symptoms such as dull or aching pain in the groin or thigh Bilateral incomplete or complete femoral diaphysis fractures Delayed fracture healing Specifically excluded are fractures of the femoral neck, intertrochanteric fractures with spiral subtrochanteric extension, pathological fractures associated with primary or metastatic bone tumors, and periprosthetic fractures Presentation History long history of bisphosphonate or denosumab history of thigh pain before trauma occurred Symptoms hip and thigh pain inability to bear weight Physical exam pain with motion typically associated with obvious deformity (shortening and varus alignment) flexion of proximal fragment may threaten overlying skin Imaging Radiographs recommended views AP and lateral of the hip AP pelvis full length femur films including the knee optional views traction views may assist with defining fragments in comminuted patterns but is not required findings proximal fragment flexed and abducted distal fragment adducted and ER bisphosphonate-related fractures have login to view 5 more bullets Treatment Nonoperative observation with pain management indications login to view 2 more bullets Operative intramedullary nailing (usually cephalomedullary) indications login to view 4 more bullets fixed angle plate indications login to view 4 more bullets Techniques Intramedullary Nailing position lateral positioning login to view 3 more bullets supine positioning login to view 4 more bullets techniques 1st generation nail (rarely used) 2nd generation reconstruction nail cephalomedullary nail trochanteric or piriformis entry portal login to view 1 more bullet pros preserves vascularity load-sharing implant stronger construct in unstable fracture patterns cons reduction technically difficult login to view 3 more bullets mismatch of the radius of curvature login to view 1 more bullet complications varus malreduction (see complications below) Fixed angle plate approach lateral approach to proximal femur login to view 2 more bullets technique 95 degree blade plate or condylar screw sliding hip screw is contraindicated due to high rate of malunion and failure blade plate may function as a tension band construct login to view 1 more bullet cons compromise vascularity of fragments inferior strength in unstable fracture patterns Complications Varus/ procurvatum malunion the most frequent intraoperative complication with antegrade nailing of a subtrochanteric femur fracture is varus and procurvatum (or flexion) malreduction Nonunion rates of nonunion lowest when using reamed, statically locked IMN can be treated with plating allows correction of varus malalignment Bisphosphonate fractures nail fixation increased risk of iatrogenic fracture login to view 1 more bullet increased risk of nonunion with nail fixation resulting in increased need for revision surgery login to view 1 more bullet bisphosphonates must be discontinued login to view 1 more bullet plate fixation increased risk of plate hardware failure login to view 1 more bullet