Case Study of Subtrochanteric Femur

PREPARED BY: JOHN RESS A. ESCOBAL GROUP 1

SUBMITTED TO: TERESITA SAN JOSE RN, MAN

I. INTRODUCTION Subtrochanteric Femur Subtrochanteric fractures are fractures that occur in a zone extending from the lesser trochanter to 5cm distal to the lesser trochanter, however extension into the intertrochanteric region is common. These fractures are more difficult to treat as compared to intertrochanteric fractures due to the powerful muscle forces acting on the fragments as well as the tremendous stress that is normally placed through this region. When seen in young patients, they are due to high-energy trauma or pathologic fracture with 10% of high-energy fractures due to gun shot wounds. In the elderly, they are often low energy injuries involving osteoporotic bone. Pathologic fractures account for 17-35% of all subtrochanteric fractures. Fracture may also occur at the site of screw placement for a previous femoral neck fracture if the inferior screw is placed too low (below the lesser trochanter), as this creates a cortical defect and stress riser.

Risk Factors Any condition that generally (such as osteoporosis) or focally (such as metastatic disease) weakens the bone may predispose to such an injury with low-energy trauma or even without trauma.

Etiology In elderly patients, minor slips or falls that lead to direct lateral hip trauma are the most frequent mechanism of injury.5,3 This age group is also susceptible to metastatic disease that can lead to pathologic fractures. In younger patients, the mechanism of injury is almost always high-energy trauma, either from direct lateral trauma (eg, motor vehicle accident [MVA]) or from axial loading (eg, a fall from height). Gunshot wounds cause approximately 10% of high-energy subtrochanteric femur fractures. Two types of Subtrochanteric Femur:

Low subtrochanteric fracture Below lesser trochanter with piriformis fossa intact Treatment = standard locked IM nailProximal fragment is typically externally rotated and flexed due to the pull of the iliopsoas Distal fragment is displaced medially by the adductor magnus.

(Iliacus/ Psoas) and abducted by the short abductors inserting into the greater trochanter.

High subtrochanteric fracture Fractures with extention above the lesser trochanter Treatment = locked cephalomedullary nail. Beware of varus malreduction. The primary reason for this is failing to counteract the muscle forces acting on the proximal fragment combined with the adducted position of the distal femur during portal creation. Ensure anatomic reduction before guide wire and nail insertion. A clamp placed on the proximal fragment can be used to control proximal fragment movement and prevent eccentric reaming. In addition, excessive adduction of the distal fragment during reaming and nail placement should be avoided. (French BG, Tornetta P III: Clin Orthop 1998;348:95-100). Signs and Symptoms The clinical picture often is not subtle and resembles that in any patient with an intertrochanteric or a femoral shaft fracture. Pain and deformity are common, although nondisplaced fractures also are seen.Physical Exam Generally, a shortened extremity with a swollen thigh is most evident on examination. A complete neurovascular examination of the extremity should be performed. An open injury should be ruled out. Tests LaboratoryA complete blood count to evaluate the hematocrit is advisable in patients with any trauma.

Preoperative laboratory tests should be obtained in case operative treatment is necessary.

Urine and serum electrophoresis may be obtained if pathologic fracture is suspected. Imaging Radiography: AP radiographs of the pelvis and AP and lateral films of the hip and femur should be obtained with particular attention being paid to including the femoral neck to rule out concurrent, ipsilateral injury and to help dictate treatment options. The cross-table lateral hip view is advised rather than the frog-leg view. Classification Fielding Classification - This is an anatomic classification based on location of the fracture and is rarely used Type I - at level of lesser trochanter Type II -