Dr. Kevin Yip

Dr Kevin Yip
Orthopaedic Surgeon
MBBS(UK), FRCS(EDIN), FAM(SING), FHKCOS(ORTHO)

Featured on Channel NewsAsia

Subtrochanteric Fracture

Basics
Description
  • By definition, subtrochanteric hip fractures (or, simply, subtrochanteric fractures) extend into the region between the lesser trochanter and a point 5 cm distally.
  • Classification:
    • Multiple systems exist, but prognostically the most critical factor is fracture stability, which is based on the degrees of comminution of the medial and posteromedial cortex.
    • The Russell and Taylor classification :
      • Useful for guiding treatment because it differentiates fractures that extend into the piriformis fossa from those that do not.
      • This distinction is important because a cephalomedullary nail enters the femur at the piriformis fossa and therefore should not be used if the fossa is fractured .
  • The medial and posteromedial cortices sustain the great compressive forces.
    • Comminution in this area renders the fracture unstable.
General Prevention
  • Fall precautions in the elderly
  • Wearing safety belts in automobiles
Epidemiology
  • A bimodal age distribution:
    • 1/3 of these fractures occur in patients >50 years old .
  • Young patients typically present after undergoing high-energy trauma, whereas low-energy trauma is the typical cause in the geriatric population .
Incidence
Subtrochanteric fractures account for ~10-34% of all hip fractures .

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 young patients with normal bone, the mechanism of injury is high-energy trauma, as occurs in motor vehicle collisions, falls from substantial heights, or gunshot wounds.
  • In the geriatric population with weakened bone, low-energy trauma (such as a minor fall) is a more common cause.
  • Less commonly, the pathologic fracture occurs in which weakened bone stock (e.g., secondary to neoplasm or metabolic bone disease) is unable to withstand the mechanical stresses of normal ambulation or other low-impact activity.
  • The mechanical stresses on the femur are highest in the subtrochanteric region.
Associated Conditions
  • When the fracture is associated with high-energy trauma, a high index of suspicion should exist for other injuries in the ipsilateral extremity or pelvis and elsewhere (e.g., cranial and vertebral injuries).
  • These injuries can be associated with substantial hemorrhage; therefore, the patient should be monitored for hypovolemic shock.
  • In addition, compartment syndrome of the thigh is possible, although rare.
  • With any such fracture associated with previous symptoms of pain, a limp, or with minimal trauma, neoplasm should be ruled out by appropriate methods, including bone biopsy at the time of treatment.
Diagnosis
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.
History
Trauma or fall
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
Lab
  • A 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.
Pathophysiology
  • The proximal portion of the femur is pulled into abduction, external rotation, and flexion by the gluteus, external rotator, and iliopsoas muscles, respectively.
  • The distal fragment is pulled proximally and into varus by the iliopsoas, producing a shortened femur with varus deformation.
  • Recognition of these deformities is important and aids the surgeon in reducing the fracture.
Differential Diagnosis
  • Traumatic injury
  • Pathologic fracture
Treatment
General Measures
  • Initial assessment after the trauma includes the ATLS protocol when appropriate.
    • Treatment of any urgent concomitant injuries should be done while traction splinting is in place.
  • Skeletal traction should be initiated if the patient is going to be treated nonoperatively or if surgical fixation will be delayed.
  • Nonoperative treatment may be indicated for elderly patients who are poor operative candidates.
    • Skeletal traction or cast bracing may be used, although these treatments commonly result in shortening, rotational or varus deformity, malunion, or nonunion.
  • After the immediate posttraumatic stabilization and workup, medical issues include intravascular volume, antithromboembolic prophylaxis (keeping in mind the timing of definitive surgical management), and treatment of pre-existing medical problems.
Pediatric Considerations
  • Unless the bone is weakened by an inherent process such as a simple bone cyst, fibrous dysplasia, or osteoporosis, subtrochanteric femur fractures in children are secondary to high-energy trauma and much less common than more proximal femoral fractures.
  • The vascular supply to the femoral head is not at risk as it is in femoral neck fractures.
  • The potential for leg-length discrepancy is present even if no obvious damage to the physis is present.
    • Attention to leg length and rotational orientation should be a priority during treatment.
  • Treatment can involve closed reduction and spica cast, external fixation, or internal fixation.
Activity
  • Patients should be nonweightbearing until definitive stabilization of the fracture.
  • Postoperative weightbearing:
    • Toe-touch weightbearing with crutches or a walker should be initiated within the first 2-3 days.
    • Full weightbearing should be achieved gradually over a 3-month period, guided by radiographic healing.
  • Elderly patients are allowed to bear weight as tolerated.
Special Therapy
Physical Therapy
Patients may begin ROM and hip strengthening in the early postoperative period.

Medication
Narcotic pain medicines are necessary after subtrochanteric fractures.
Surgery
  • Open reduction and internal fixation comprise the treatment of choice for most fractures because this approach allows for early mobilization and better achieves near-normal anatomy than do nonoperative procedures.
  • The goals of treatment are to restore femoral length and rotational alignment and to maintain the abductor muscle lever arm by preventing varus deformity.
  • Because this area of the femur undergoes substantial compressive and tensile stresses with normal gait, implant failure is of concern, particularly with unstable fractures.
  • The main operative treatment options include static interlocking nails, cephalomedullary reconstruction nails with locking screws placed into the femoral head, a sliding hip screw, and a 95° angled blade plate.
    • Static interlocking nails can be used if both trochanters are intact.
    • Cephalomedullary nails are indicated if loss of the posteromedial cortex is present.
    • A sliding hip screw can be used only for proximal fractures because the compression screw must cross the fracture and, for compression to occur, the plate cannot be fixed to the proximal fragment.
    • A device called the Medoff plate allows sliding along the head-neck axis and the shaft.
      • Results in a blinded study comparing the Medoff plate to an intramedullary nail favored the use of the nail.
      • A 95° angled blade plate has been shown to provide good results when a sliding hip screw cannot be used because of comminution in the trochanteric area and fracture extension into the lateral cortex.
      • Dynamic condylar screw plate fixation is not as reliable as intramedullary nail fixation.
Follow-up
  • Patients should be seen within 1-2 weeks after surgical fixation to confirm fracture and implant stability.
  • Subsequently, they should be seen monthly to assess healing radiographically and clinically.
Prognosis
  • Most patients can return to near-prefracture activity level, given appropriate treatment.
  • A recent review of 302 patients with low-energy subtrochanteric fractures treated with a cephalomedullary nails found that:
    • At 1 year, 34.5% of the patients had died.
    • Survivors had an increased level of social dependence, an increased use of walking aids, and reduced mobility.
    • Of the 211 patients who were evaluated at 1 year after the injury, 42% had some degree of hip discomfort but only 2 described the pain as severe and disabling.
    • Reoperation was required in 8.9% of the patients, with a 1-year nail revision rate of 7.1%.
    • 2% of the patients had nonunion.
Complications
  • The most common complications of treatment of subtrochanteric fractures are nonunion, malunion, shortening, and implant failure.
  • Stable, near-anatomic reduction and internal fixation of these injuries with attention paid to avoiding premature weightbearing help decrease the incidence of such complications.
  • Loss of fixation in plate and screw devices usually is secondary to screw pullout from the femoral head in osteoporotic bone and should be managed with revision to an intramedullary nail.
  • Failure of interlocking nails can be secondary to failure to lock the device statically, fracture at the entry site, or an undersized nail.
    • These complications can be treated with nail replacement using a larger-diameter nail.
  • Penetration of the distal anterior femoral cortex also is a potential complication with an intramedullary nail.
  • Nonunion is defined by pain or tenderness at the fracture site after 3-6 months.
  • Symptoms of malunion include limp, rotational deformity, and leg-length discrepancy.
    • Treatment involves valgus osteotomy, revision internal fixation, and bone grafting.
  • AVN of the femoral head may occur in children with open physes, if standard intramedullary nailing is performed through the piriformis fossa.
Miscellaneous
Codes
ICD9-CM
820.32 Subtrochanteric fracture
Patient Teaching
  • Patients should be advised of the risk of malunion, nonunion, or implant failure, especially if they have osteoporotic bone.
  • Protected weightbearing in the early postoperative period is essential to allow adequate reconstitution of this mechanically stressed area.
FAQ
Q: What is the best treatment for a subtrochanteric femur fracture?
A: Intramedullary nailing using a cephalomedullary device allows for stable fixation of subtrochanteric fractures. Reduction and anatomic fixation is paramount. The fracture must be reduced before nail insertion.

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