11 Extracapsular Hip Fractures
Incidence and Etiology
I. Intertrochanteric femur fractures:
Increasing incidence and will likely approach 500,000 per year by 2040. 1
More common in women older than 65 years of age.
About one-third of women reaching the age of 90 years will sustain a hip fracture. 2
Patients with osteoporosis are at increased risk for intertrochanteric femur fractures.
Increased incidence of falls in the elderly population.
Postural and gait disturbances.
Decreased visual and hearing acuity.
Usage of one (or multiple) disorienting medications.
Associated fractures include the following:
Usually have grossly displaced fractures.
Pathologic fractures from metastasis.
II. Subtrochanteric femur fractures:
Asymmetric age- and gender-related bimodal distribution:
Usually motor vehicle accidents.
Fall from heights.
Mostly females. 3
(i) Atypical fractures.
(ii) Bisphosphonate use greater than 3 to 5 years.
Associated injuries involving other extremities:
Commonly seen in high-energy mechanisms. 3
Subtrochanteric femur fracture can result from prior surgery:
Screw fixation of ipsilateral femoral neck fracture:
Screw starting point distal to the lesser trochanter.
Core decompression and vascularized free fibula autografting for avascular necrosis of the femoral head:
Lateral cortical defect is below the lesser trochanter.
Pathologic fractures from bisphosphonate use or metastasis.
Intraosseous Scaffold of Trabecular Bone Supports Femoral Head and Neck (Fig. 11.1)
I. Primary compressive group:
Dense cancellous bone.
II. Secondary compressive, tensile, and greater trochanter groups:
Oriented along stress lines in the lateral femoral neck.
Relative paucity of trabecular scaffolding in the central area also called Ward’s triangle. 4
III. Changes in the trabecular pattern affects bone density.
Numerous Muscle Attachments to the Intertrochanteric Area
Muscular Forces Dictate Direction of Displacement
Pulls on its insertion at the lesser trochanter.
II. Abductors and external rotators:
Act through their attachments at the greater trochanter.
Leads to shortened and externally rotated extremity in displaced fractures, especially intertrochanteric femur fractures with subtrochanteric extensions or subtrochanteric femur fractures.
Intertrochanteric Femur Fractures 5
I. Stable fracture:
Fractured in only one place.
Lateral cortex: intact.
Withstands axial loads:
Without displacement after anatomic reduction.
II. Unstable fracture:
Large fragment or comminuted.
Fracture below the vastus ridge.
May be standard or reverse.
Fracture collapses with axial loading after reduction.