The majority of hip fractures occur in the geriatric population following minimal trauma (ground level fall) in combination with diminished bone quality. Significant morbidity and mortality can accompany these injuries, with poor baseline functional status and associated medical co-morbidities further heightening risks of adverse outcomes.
Hip fractures in young adults generally follow high-energy injuries, with significant potential for development of long-term functional deficits. These orthopaedic “emergencies” (femoral neck fracture, native hip dislocation) require high index of suspicion and timely intervention to decrease potential life-altering effects.
Structure and function
The adult proximal femur is comprised of distinct anatomic regions, including head, neck, intertrochanteric, and subtrochanteric components. The femoral neck is further subdivided into subcapital, transcervical, and basicervical regions descending in a cranial to caudal direction.
The former two divisions are intracapsular, with a tenuous blood supply easily disrupted following displaced fracture. This heightens risks for non-union and avascular necrosis (AVN). The latter location better identifies with extracapsular principles, with an abundant blood supply demonstrating elevated healing rates.
Bone density of the proximal femur declines with age, as does its associated mechanical properties. Its largely cancellous foundation experiences preferential loss regarding accepted osteoporosis and aging doctrine, thus propensity for fracture increases with age.
The femoral head receives its blood supply from three sources, mainly the medial circumflex artery, with smaller contributions from the lateral circumflex and artery of the ligamentum teres. Ascending branches course along the femoral neck, entering the head as the united lateral epiphyseal arteries, mostly from a posterosuperior location. Preservation of the blood supply in intracapsular fractures (femoral head/neck) is the dominant variable affecting treatment parameters and long-term outcomes.
The intertrochanteric region (IT) of the proximal femur contains the greater trochanter (GT), extracapsular region of the femoral neck (basicervical), and extends distally to the lesser trochanter (LT). Injuries generally produce a shortened and externally rotated extremity, with associated varus deformity of fracture fragments. This acquired positioning is secondary to multiple muscular deforming forces and their related femoral attachments.
The subtrochanteric region (ST) is found between the LT and a region 5cm distal, or the junction of the proximal and middle thirds of the femur. It is a site of high biomechanical stress, but in contrast to the more proximal femur, is composed of denser cortical bone. Fractures can occur in isolated fashion, but also commonly accompany more proximal femur fractures. Significant blood loss may follow injury, thus meticulous assessment of hemodynamic status is a priority.
Approximately 90% of hip fractures occur in patients greater than 65 years of age, with about 75% affecting the female population. Mortality ranges from 7-27% within 3 months of injury, while femoral neck fractures alone have an approximate 10- 20% one year mortality rate when compared to age-matched controls without fracture.
Femoral neck and intertrochanteric fractures are by far most common regions affected, generally observed in the geriatric population secondary to minimal trauma and associated poor bone quality. Young patients may also suffer fractures of the femoral neck and/or femoral head with associated hip dislocation, however these injuries require higher energy forces based upon intrinsic hip stability.
Subtrochanteric fractures occur in a bimodal age distribution, with traumatic mechanism similar to aforementioned demographics. Ten percent are due to gunshot injuries, while up to 1/3rd are considered pathologic.
Recent estimate of cost for treatment of hip fractures in the US range up to 10 million annually, with this cost expected to double by 2040. Outcomes are based upon age, bone quality, fracture location/severity, associated injuries, treatment, and related co-morbidities.
Extreme burden may affect all hip fracture patients, with pain and functional decline a staple of the younger population. This reflects need for emergent intervention and limited long-term treatment options. Moreover, diminished ambulatory capacity, a loss of independent living and/or a potential loss of life exemplify the unsettling consequences faced by the geriatric population.
The most common mechanism of femoral head fractures involves motor vehicle collisions. There is high association with acetabular fractures and/or posterior hip dislocations based upon axial loading and associated “dashboard” injuries. High suspicion and timely reduction are paramount, with assessment of baseline neurovascular function an essential initial component.
The majority of remaining hip fractures are generally secondary to low energy trauma in patients with osteopenic/porotic bone, while young adults are exposed to high energy/velocity forces. Depending upon history and mechanism, patients may require additional testing (syncopal work-up) to better evaluate etiology and/or treatment measures (intravascular fluid repletion) to medically optimize conditioning prior to actual hip fracture management.
Clinical suspicion for a hip fracture is based upon history, physical examination (lower leg deformity-generally shortened and externally rotated), and associated provocative maneuvers (axial loading of the hip joint via percussion of sole of foot with the knee extended). Baseline neurovascular status and overlying skin integrity should also be strictly documented.
Many elderly patients are disoriented upon presentation, and may not be able to accurately articulate history surrounding their injury, as well as discomfort from associated pathology. Special attention to areas instrumental in absorbing impact during a fall should be inspected, palpated, and ranged (clavicle, wrist, elbow, proximal humerus). Overlying skin abrasions and/or bony crepitus may also lend clues to underlying fracture.
Adjacent organ involvement is common in high-energy injury mechanisms, thus full trauma evaluation is required.
Figure1. R hip fracture-shortened, ER ext
Patients whose presentation are suggestive of hip fracture with negative initial imaging require advanced studies. It is essential to detect an “occult” hip fracture which can displace upon weight-bearing. MRI is generally the study of choice, with CT implemented in patients with contraindications to MRI-metal in the heart (pacemaker), eye (shrapnel), and brain (aneurysm coil).
Any patient presenting with a proximal femur fracture requires scrutiny of the femoral neck and analysis for evidence of subtrochanteric extension. ST fractures can masquerade as intertrochanteric fractures, with a failure to appreciate their presence leading to unsuspected difficulty with surgical management. Traction radiographs and/or CT, with reference to potential pathologic fractures, may help decrease this risk.
With non-displaced femoral neck fractures, extreme caution must be exercised during physical examination, imaging, and transfers as to not cause fracture displacement. This can alter surgical management and create potential for diminished long-term outcomes. A cross-table lateral image of the hip allows the affected limb to remain undisturbed while evaluation is performed.
Stability of fracture-implant construct is dependent upon five factors:
- Bone quality
- Fracture pattern
- Quality of fracture reduction
- Design of chosen implant
- Positioning of implant
The operating surgeon can influence the latter three, but must scrutinize the former two to potentially achieve optimal results.
The proximal thigh envelops a large compartment whereby much blood can accumulate. Monitoring for hypovolemia in consideration of high energy mechanisms, especially subtrochanteric fractures, should be a recognized priority. Provisional splinting/immobilization can decrease pain, control hemorrhage, limit soft tissue damage, and prevent further injury.
Patients with femoral head fractures likely also suffered a hip dislocation, thus timely reduction and neurovascular evaluation is critical, especially sciatic nerve function.
Radiographic examination requires an AP Pelvis/AP Hip with the lower extremity in approximately 10-15 degrees of internal rotation. This allows evaluation of fracture location/obliquity, presence/absence of comminution, and full profile of the femoral neck. A cross-table lateral will delineate the relationship of the femoral head and neck, associated posterior fracture fragments, and “sag” that is imperative in pre-operative planning. A full-length femur film that includes the knee can rule out associated pathology, and is required if fixation requires a long-stemmed implant spanning the femur.
Traction radiographs involving axial traction and slight internal rotation can better delineate fracture patterns regarding anatomic level and associated comminution, while radiographs of the contralateral extremity can help assess proper length and rotation required for optimal surgical repair.
AP Pelvis. Position: supine, lower extremity IR 10-15°
AP Left Hip. Position: supine, extremity IR 10-15°
CROSS-TABLE HIP X-RAY. Beam: centered on femoral neck
MRI is recommended for evaluation of an “occult” fracture, with increased areas of signal uptake delineating bony edema suggestive of fracture.
MRI-Coronal view-R Hip Fracture
CT scan is an acceptable alternative, however there is increased patient radiation exposure. Nevertheless, it is the modality of choice with respect to evaluation of the femoral neck, especially in association with femoral shaft fractures.
Femoral head fractures are classified according to Pipkin, with Type I associated with hip dislocation and fracture below the fovea capitis. Assuming concentric hip reduction, it is the only pattern generally managed non-operatively based upon its isolated involvement and non-weight bearing location.
Femoral Neck fractures are described by Garden and/or Pauwels classifications. Garden is based upon amount of valgus displacement, while Pauwels examines the angle the fracture makes with the horizontal. Increasing angles represent higher shear forces, thus greater potential for collapse.
Incomplete, impacted fracture in valgus position
Complete, non-displaced fracture
Complete fracture, with partial displacement
Complete fracture, with complete displacement. Femoral head and supra-acetabular trabeculae remain aligned
30 degrees-essentially horizontal, minimal shear forces, with lowest risk of varus collapse.
50 degrees-intermediate inclination angle.
70 degrees-almost vertical angle, highest risk of collapse & non-union with conservative treatment.
PAUWELS FEMORAL NECK FX CLASSIFICATION
Intertrochanteric fractures can be described based upon a four-part classification system (GT, LT, Femoral head/neck, and shaft) or in consideration of stability (stable vs. unstable) as determined by posteromedial bony contact. This key anatomic region acts as a buttress against potential for fracture collapse. Most orthopaedic surgeons implement the latter binary classification scheme, which not only directs treatment, but is also somewhat prognostic.
Subtrochanteric fractures are described according to the Russell-Taylor Classification. It is based upon mechanical stability and fracture extension. Type IA does not extend into the piriformis fossa, with no comminution of the LT. Type IB fractures also have an intact piriformis fossa, but there is comminution of the
LT. Type II fractures have extension into the piriformis fossa.
RUSSELL-TAYLOR ST CLASSIFICATION
Risk factors and prevention
Risks of sustaining a hip fracture in the elderly can be minimized by a multitude of interventions:
- maintaining/increasing physical strength and overall functional conditioning
- education regarding fall risks (modification of home environment, wearing appropriate footwear, medication effects, etc.)
- testing/treating any impairment of visual/vestibular/auditory function
- minimizing bone loss and risks of osteoporosis by adhering to recommended dietary intake of Vitamin D and calcium
- participating in screening to evaluate risks of osteopenia/porosis, along with need for treatment (bisphosphonates)
- quitting smoking, decreasing alcohol intake, and maintaining appropriate bodyweight
Associated injuries can include the entire extremity, but the acetabulum, femur, and knee tend to be most susceptible in the geriatric population. Higher energy mechanisms generally carry greater risk of associated injury, however diminished bone quality may obviate this mantra in certain cases.
Bed-bound, non-ambulatory patients or those with multiple medical co-morbidities may undergo an initial trial of non-operative management with appropriate analgesic support if risks outweigh the potential benefits of surgical intervention.
Goals of surgical treatment are to minimize patient discomfort, restore function, and allow rapid mobilization by obtaining early anatomic reduction and stable internal fixation or by implementing prosthetic replacement.
Treatment of femoral head fractures can range from benign neglect with protected weight-bearing, to excision, internal fixation, reconstruction and/or hip fusion. Generally, Pipkin I fractures are treated non-operatively because they do not involve the weight-bearing surface, however surgical intervention is generally required for most other femoral head fracture patterns.
Valgus impacted and associated non-displaced intracapsular femoral neck fractures require internal fixation to prevent displacement. Percutaneous in situ fixation with three cannulated screws in an inverted triangle position attempts to prevent varus collapse, however care must be exercised to avoid intra-articular placement. This can lead to pain and progressive joint degeneration.
Displaced intracapsular fractures are generally treated based upon “physiologic”, not chronologic age. This includes examination of associated injuries, bone quality, previous functional level, and co-morbidities. Closed reduction and percutaneous in situ fixation versus open reduction and internal fixation with associated capsulotomy is generally implemented in the “physiologically” young. The ancillary procedure is thought to disrupt hematoma formation and preserve blood supply to the femoral head in efforts to reduce risks of non-union and AVN.
Prosthetic replacement of the proximal femur (hemiarthroplasty) is generally reserved for the physiologically elderly, with poor bone quality and limited functional requirements. Advanced chronologic age, yet “physiologically” young, with remaining high level of function, and/or patients with pre-existing acetabular disease (OA, RA) may undergo primary total hip replacement based upon surgeon/patient preference.
IN SITU FIXATION-FEMORAL NECK FRACTURE
HEMIARTHROPLASTY--proximal femur replaced only
TOTAL HIP ARTHROPLASTY-proximal femur & acetabular articulation replaced
Basicervical (extracapsular) femoral neck fractures and “stable” intertrochanteric fractures are generally treated with a compression/dynamic hip screw system. These implants allow controlled fracture impaction based upon an intact lateral wall buttress.
“Unstable” IT fractures (Reverse Obliquity, IT fxs w/ ST extension, and those lacking an intact lateral wall) require an intramedullary implant to prevent fracture collapse associated with tendency for medialization of the femoral shaft fragment. Greater stability is achieved through shorter lever arm-shaft fixation, as support moves from the disrupted lateral cortex to the intramedullary region. Markedly osteopenic/porotic patients, those with rheumatoid arthritis, pathologic fractures, and those requiring salvage procedures following failed prior reconstruction, may undergo calcar-replacing hemiarthroplasty.
4-part “unstable” IT fracture
Treatment of subtrochanteric fractures involves placement of intramedullary implants, whether standard interlocking nails, or cephalomedullary (reconstruction and trochanteric femoral) nails that also engage the femoral head. These implants are also used to treat combination proximal femur fractures. Previously, 95-degree blade plates were popular, but have lost following based upon difficulties with surgical technique.
ST Fracture-Intramedullary Implant Fixation
Outcomes of hip fracture patients encompass numerous factors, with actual surgical intervention but one component. Initial resuscitation, associated pre-operative management, and the ensuing post-operative period are also critical components to optimize regarding maximization of outcomes. Young adults may experience long-term morbidity, with limited treatment options available to address pain and/or functional loss.
Patients with femoral head fractures may experience bony fragment resorption and/or AVN largely from trauma based on the initial injury. Both sides of the joint can suffer articular damage leading to post-traumatic arthritis, while disruption of the surrounding soft tissue/musculature can lead to peri-articular fibrosis and heterotopic ossification.
Prognosis for intracapsular femoral neck fractures is largely based upon damage to the blood supply. Non-union is rare with conservative treatment of a non-displaced and/or impacted femoral neck fracture, versus a 50-60% rate following a displaced fracture. Likewise, approximately 5% of patients with impacted and non-displaced fractures treated surgically will experience non-union versus roughly 25% of those with displaced fracture. Moreover, AVN can complicate up to 10% impacted and non-displaced fractures, versus almost 30% of displaced fractures treated surgically.
Prosthetic replacement avoids complications related to non-union and AVN, but is more invasive, and can cause pain secondary to loosening/acetabular erosion, with the need for revision surgery or conversion to total hip replacement. Also, the functional results may be worse than undergoing primary hip replacement.
The risk of non-union and osteonecrosis is considerably lower in extracapsular fractures based upon abundant blood supply. Risk of non-union is only 1-2% regardless of initial treatment regimen. The prognosis generally depends upon ability to recreate stability with respect to the posteromedial cortex.
Regarding subtrochanteric fractures, limited proximal bone of poor quality may be amenable for fixation, especially in elderly patients, while multiple muscular deforming forces may also complicate reduction maneuvers, further contributing to potential loss of fixation. However, accurate reduction, precise surgical technique, including minimal soft-tissue dissection, can routinely produce good results. There is an overall low rate of non-union if excessive disruption of the medial soft-tissue envelope is avoided.
Treatment of non-union depends upon age, bone quality, level of function, and medical history. Options include repeat internal fixation and/or reconstruction versus prosthetic replacement. Only 1/3rd of patients with AVN generally require additional surgery, whereas approximately 75% with non-union undergo further surgical intervention.
Level of activity prior to injury, living situation, and medical co-morbidities are important parameters that should be documented upon presentation. Approximately 50% of elderly hip fracture patients fail to regain pre-operative level of function secondary to direct impact of the fracture and/or decline in physical/mental conditioning. This can result in a loss of independent existence, affecting many lives other than the actual patient.
Antecedent hip/thigh/groin pain may suggest pathologic fracture indicative of potential malignancy. It requires further work-up.
Lesser Trochanter is a posterior structure which can suggest hip rotation. Increased prominence indicates more external rotation of the hip, thus a diminished femoral neck profile.
Isolated Lesser Trochanter avulsion suggests a pathologic process in adults, however a common injury in children following forceful contraction of the iliopsoas muscle.
Calcar femorale-densest bone of the proximal femur. Helps transmit weight of body to lower extremity.
DOHR CLASSIFICATION-BONE QUALITY ASSESSMENT OF PROXIMAL FEMUR
Isthmal width (FW)/Calcar width (CW)
Type A=FW/CW<50% (Poor bone quality, “champagne flute”)
Type B= FW/CW=50-90% (Intermediate)
Type C= FW/CW=>90% (Good bone quality)
A: normal taper top/thick cortex, C: loss of taper/thin cortex, and B: intermediate
Reverse Obliquity Fracture: oblique fracture pattern extending from proximal medial to distal lateral. Requires an intramedullary placed implant device to prevent shaft medialization and associated collapse with lateral-based implants.
REVERSE OBLIQUITY FRACTURE PATTERN
During in-situ fixation of a femoral neck fracture, screw placement should be above the level of the lesser trochanter to avoid creation of a stress riser and risk for subsequent subtrochanteric fracture.
Basicervical fracture patterns may require proximal guidewire/screw placement for stabilization prior to lag-screw insertion into the femoral head. This will prevent rotation of the femoral head as the lag-screw is advanced.
BASICERVICAL HIP FX: Placement of CHS & proximal de-rotational screw.
Previous fragility fracture is a strong predictor for subsequent occurrence. It is imperative to receive an appropriate bone density evaluation, specially a DEXA scan, to assess risk and need for potential treatment (bisphosphonates). Unfortunately, most patients do not receive appropriate evaluation, especially males, while racial disparities have also been identified.
Stress (fatigue) fractures occur secondary to cyclical loading on pathologic (OA,RA patients) and normal bone (military personnel) on the medial (compressive) and lateral (tension) aspects of the femoral neck. Lateral-side involvement requires surgical stabilization, with a high propensity for displacement, while medial-side involvement is treated with protected-weight bearing until radiographic evidence of healing.
Avascular Necrosis (AVN) involves cellular death of bone following disruption to blood supply. It can be manifested as pain in the proximal thigh, groin, or buttock. Treatment can be conservative (analgesia/protected weight-bearing), or with various surgical procedures depending upon severity of collapse of the femoral head.
NON-UNION-radiographic and/or clinical symptoms suggesting decreased/failure of fracture healing.
Isolated GT fracture-if minimally displaced/elderly pt, can treat with protected weight-bearing versus active pt w/ significant displacement, should have repaired with cable and/or tension band techniques, including attached abductor musculature.
Tip-Apex Distance-originally applied to fixation of IT fractures, whereby distance from tip of screw to apex of the femoral head is measured on the AP and Lateral views. Their sum should be <25 mm to diminish risks of compression-screw cut-out and associated fixation failure.
“Atypical” ST fracture pattern (transverse fracture): when associated with prodromal symptoms and long-term bisphosphonate use, may be considered a type of “insufficiency” fracture-a topic of debate.
1) What structure provides the main blood supply to the femoral head?
2) What is the most common complication following a femoral neck fracture?
Hip, Femoral Neck, Osteopenia/Osteoporosis, Fragility Fracture, Intertrochanteric Fracture, Subtrochanteric Fracture, Non-Union, AVN, Bisphosphonates, Hemiarthrioplasty, Total Hip Arthroplasty
Radiographic Analysis, Orthopaedic Emergencies (“physiologically” young pt with hip dislocation/fracture), Pre-operative medical evaluation/optimization