Subtrochanteric fractures occur in the region of the femur between the lesser trochanter and 5 cm distal to it. They are challenging injuries to treat due to strong muscle forces and high stresses in this region. Surgical stabilization with an intramedullary nail is usually recommended to provide rigid fixation while minimizing stress on the implant. Care must be taken to achieve and maintain an anatomical reduction to prevent complications like malunion and nonunion. Long-term bisphosphonate use may be associated with an increased risk of subtrochanteric fractures with a characteristic radiographic appearance.

1. Introduction
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
fractures¹. 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.
Anatomy
Subtrochanteric fractures are fractures that occur in a zone extending from the lesser trochanter to 5cm
distal to the lesser trochanter. The medial and posteromedial cortices of the subtrochanteric femur
experience the highest compressive stresses in the body. The lateral cortex is under a high degree of
tensile stress. These fractures occur at the cortico-cancellous junction. The high composition of cortical
bone and subsequently the decreased vascularity impairs the capacity for healing of these fractures
when compared to the abundant cancellous bone of the intertrochanteric region of the hip.
The proximal fragment is usually flexed and externally rotated by the pull of the iliopsoas and short
external rotators, and abducted by the pull of the gluteus medius and minimus. The distal fragment is
adducted and shortened by the pull of the adductors leading to a varus and procurvatum fracture
alignment. These factors should be considered when attempting reduction.
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 - <2.5 cm below lesser trochanter
Type III - 2.5-5cm below lesser trochanter

2. Seinsheimer Classification - This system incorporates factors affecting stability and offers management
guidelines.
Type I - nondisplaced
Type II - two part fractures
Subtypes based on fracture pattern and displacement
Type III - three part spiral fracture
Subtypes based on type of fracture fragments
Type IV - comminuted
Type V - intertrochanteric extension
Russell-Taylor Classification - This classification is based on integrity of the piriformis fossa. It was
designed to guide treatment of intramedullary nails using a piriformis fossa starting point. This system
may not be as important as it used to be, due to changes in entry point techniques and improved
implant designs¹.
Type I - intact piriformis fossa
A - lesser trochanter attached to proximal fragment
B - lesser trochanter detached from proximal fragment
Type II - fracture extends into piriformis fossa
A - stable posterior-medial buttress
B - comminution of lesser trochanter
Orthopaedic Trauma Association Classification - Based on degree of comminution and mainly used for
research purposes.
Presentation
Patients typically present in significant pain unable to ambulate with deformity of the proximal thigh.
High energy mechanisms should receive a full trauma evaluation and careful inspection for open
fracture. A detailed neurovascular exam of the extremity should be performed. Due to the size of the
thigh compartment, hypovolemic shock is possible secondary to this fracture.

3. Subtrochanteric Fractures and Long-Term Alendronate Use
A relationship between long-term Alendronate use and subtrochanteric fractures has been established
and is hypothesized to result from long-term suppression of bone remodeling. A retrospective case-
control study of postmenopausal women presenting with low-energy femoral fractures reported
bisphosphonate use in 15/41 subtrochanteric/shaft fractures vs. 9/82 age-, race-, and BMI-matched
femoral neck and intertrochanteric fractures (odds ratio = 4.44, 95%CI = 1.77-11.35; p = 0.002). A
common radiographic pattern consisting of a simple oblique fracture with cortical thickening and
beaking of the cortex on one side was highly associated with bisphosphonate use. Patients with this
fracture pattern had an average duration of alendronate use of 7.3 years, vs. 2.8 years for those without
the pattern 1 . Up to 76% of these patients may have prodromal pain 2 . Patients with low-energy
fractures who have been on long-term bisphosphonate therapy should have imaging of the contralateral
femur. Prophylactic fixation should be considered if a contralateral stress fracture is found 3 .
Consideration should also be given to discontinuing alendronate, in consultation with an endocrinologist
3.
Diagnosis
For all hip fractures, an AP pelvis, internal rotation AP and cross-table lateral of the affected hip should
be obtained. An MRI may also be required for pathologic fractures to evaluate the proximal femur for
soft tissue extension of an underlying bone tumor. It is helpful to obtain a contralateral femur x-ray
taken with a radio-opaque ruler or scanogram for patients with highly comminuted fractures as a means
to measure the native femur length so that it may be reproduced during ORIF of the affected extremity.
Patients with low-energy fractures who have been on long-term bisphosphonate therapy should have
contralateral femur imaging to rule out impending fractures.
Treatment
Initially, the limb should be stabilized with Hare traction, Buck's traction or skeletal traction. If there will
likely be a delay in surgical stabilization, femoral or tibial skeletal traction should likely be employed.
Nonoperative treatment in 90-90 skeletal traction followed by hip spica casting should only be
employed in those whom surgery is deemed very high risk. 90-90 traction attempts to counteract the
deforming muscular forces. Traction usually is required for 12-16 weeks.
Surgical stabilization is the standard of care. The treatment option include:

4. Intramedullary nail fixation is the preferred treatment. In general, intramedullary devices have been
found to be almost twice as strong as extramedullary implants. First generation interlocking nails
(centromedullary) are indicated when both trochanters are intact as the oblique locking screw is able to
obtain adequate purchase. Second generation interlocking nails with a locking screw that extends into
the femoral neck (cephalomedullary) offer more stable fixation and are indicated when the lesser
trochanter is displaced or comminuted. Advantages of intramedullary fixation include 1) Potential for
closed treatment with preservation of fracture hematoma and blood supply to fracture fragments, 2)
Decreased the moment arm on the implant compared to a lateral plate and thus decreases the tensile
stress on the implant, 3) Reaming the canal in preparation of the implant provides internal bone graft, 4)
intramedullary implants have been found to be twice as strong as traditional extramedullary implants.
Disadvantages include 1) the implant cannot be used to help facilitate reduction and the fracture site
may need to be opened to affect a reduction and guide pin insertion, thus lessening benefits of closed
intramedullary fixation. It is nonetheless critical to achieve reduction and to maintain this reduction
(using instruments, an incision or both as needed) while the nail is being placed. Failure to do so will
result in varus displacement during implantation. Obtainment of proper nail starting point can be eased
by lateral/lazy lateral patient positioning or the use of a trochanteric starting nail. If a trochanteric nail is
chosen, it is imperative that a very medial starting point is chosen, again to avoid varus deformity.
Russell et al have reported decreased rates of malalignment using the Minimally Invasive Nail Insertion
Technique (MINIT) 4 .
Ninety-five degree fixed-angle devices
Historically this was the most common device used for operative fixation. This is a fixed angle construct
that provides rigid fixation. Advantages include 1) Offers a treatment option for fractures with
comminution of the trochanters that may make intramedullary implant insertion difficult, 2) Provides for
multiple points of proximal fixation. Disadvantages include 1) Technically very demanding, 2) Extensive
soft-tissue dissection, 3) High risk of implant failure due to tremendous stress applied to the plate
laterally.
Sliding hip screw
This device is indicated only for very proximal fractures. The sliding of the screw allows medialization of
the distal fragment, which reduces bending moment on fracture and implant. The sliding mechanism
must cross the fracture site to lessen the risk of implant failure and the posteromedial cortex must be
reconstructed to decrease the stress on the device.
Post-Operative Care

5. Rehab: Weight bearing is guided by fracture pattern. Protected weight bearing can be started early in
fractures with posteromedial bony contact¹. Most patients should not fully bear weight for the first 6-8
weeks.
Complications
Nonunion. Incidence of 0-8% 5 . Presents with continued inability to bear weight at 4-6 months and
continued pain. Varusmalreduction is an important predictor of nonunion accompanied by implant
failure.
Malunion:
Coxavarus: Caused by uncorrected abduction deformity, nail entry point that is too lateral, and
migration of hardware proximally in the femoral head and neck.
Shortening: Due to uncorrected shortening intraoperatively and premature dynamization.
Rotational deformity: Do to uncorrected external rotation of proximal fragment. This can be assessed
intraoperatively with visualization of the lesser trochanter.
Fixation failure: Most common in osteoporotic bone. Screw cutout in the femoral head; backing out of
locking screws.
Failure of implant: Excessive motion at fracture site leads to implant fatigue.
Infection:
Red Flags and controversies

6. Plate vs. intramedullary fixation.
Role of locked plating and navigation.
Fracture may also occur at the site of screw placement for a femoral neck fracture if the inferior screw is
placed too low as this creates a cortical defect and stress riser.
Outcomes
Currently, most subtrochanteric fractures in which the piriformis fossa or greater trochanter are intact
can be successfully treated with a cephalomedullary device. Care must be taken to avoid varus during
placement of the device. Comminutedsubtrochanteric fractures may be treated with a long
intramedullary device or a fixed angled plate. Sliding hip screws should generally be avoided as they
have higher failure rates.
References:
1. Bucholz RW, Heckman JD, Court-Brown CM, Tornetta P, Koval KJ. Rockwood and Green's Fractures in
Adults: Rockwood, Green, and Wilkins' Fractures, 2 Volume Set. Sixth Edition. Lippincott Williams &
Wilkins; 2005
Sun Nov 27 04:47:04 PST 2011
1
Lenart BA, Neviaser AS, Lyman S, Chang CC, Edobor-Osula F, Steele B, van der Meulen MC, Lorich DG,
Lane JM, 2009. "Association of low-energy femoral fractures with prolonged bisphosphonate use: a case
control study." OsteoporosInt 20 (8): 1353-62 [PubMed]
2
Kwek EB, Goh SK, Koh JS, Png MA, Howe TS, 2008. "An emerging pattern of subtrochanteric stress
fractures: a long-term complication of alendronate therapy?" Injury 39 (2): 224-31 [PubMed]
3
Capeci CM, Tejwani NC, 2009."Bilateral low-energy simultaneous or sequential femoral fractures in
patients on long-term alendronate therapy." J Bone Joint Surg Am 91 (11): 2556-61 [PubMed]

7. [ab]
4
Russell TA, Mir HR, Stoneback J, Cohen J, Downs B, 2008. "Avoidance of malreduction of proximal
femoral shaft fractures with the use of a minimally invasive nail insertion technique (MINIT)." J Orthop
Trauma 22 (6): 391-8 [PubMed]
5
Lundy DW, 2007. "Subtrochanteric femoral fractures." J Am AcadOrthopSurg 15 (11): 663-71 [PubMed]
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