Darin Friess and Thomas Ellis
DEFINITION
Fractures of the femoral head are rare, and occur almost exclusively with associated high-energy hip dislocations, where they may be seen in 5% to 15% of cases.
Associated injuries to the femur, acetabulum, or acetabular labrum can affect treatment options.
ANATOMY
The spherical femoral head is almost completely covered by articular cartilage, which often is damaged during the hip dislocation.
Blood is primarily supplied to the superior dome of the femoral head by the medial femoral circumflex artery, which travels around the posterior aspect of the proximal femur, traveling deep to the quadratus femoris and penetrating the joint capsule just inferior to the piriformis tendon (FIG 1).
Additional vascular support is supplied by the lateral femoral circumflex artery and the foveal artery within the ligamentum teres.
The anterior half of the femoral neck is devoid of vascular structures. Therefore, anterior surgical approaches to the hip joint do not compromise the vascular supply of the femoral head.
The acetabular labrum increases the coverage of the femoral head, but may be damaged during hip dislocation.
PATHOGENESIS
Both the position of the leg at the time of impact and the patient's hip anatomy have been shown to play a role in the etiology of hip fracture-dislocations.
Posterior dislocations, the most common type, occur when the hip is in a flexed, adducted, and internally rotated position. Decreased femoral anteroversion leads to reduced femoral head coverage by the acetabulum and increases the risk of hip dislocation.
The fracture is a shearing injury. Injury to the articular cartilage of the femoral head is common with femoral head fractures, and posterior wall fractures also can occur with this injury.
Anterior dislocations are less common. They occur when the hip is in an abducted and externally rotated position, which results in an impaction injury to the anterolateral femoral head (FIG 2).
NATURAL HISTORY
In an intermediate-term follow-up study by Jacob et al,4 despite open or closed treatment, only 40% of patients had satisfactory results after hip dislocation at an average of 4.5 years after injury. More than half of the patients had posttraumatic arthrosis.
Osteonecrosis of the femoral head may develop in 20% of patients with femoral head fractures despite anatomic reduction.
PATIENT HISTORY AND PHYSICAL FINDINGS
Because of the high energy required to induce a fracturedislocation of the hip, all patients should undergo a thorough trauma evaluation for associated injuries.
Airway, cardiovascular, head, and spine injuries should be stabilized emergently.
Narcotic pain medication usually is required.
Careful evaluation of the affected extremity is essential.
The leg often appears shortened and internally rotated or flexed and abducted after a posterior hip dislocation.
Suspicion for associated injuries, particularly around the knee, should remain high; such injuries can be recognized on physical examination.
Injury to the knee ligaments or extensor mechanism is associated with traumatic hip dislocations and should be assessed with a stability examination.
Because sciatic nerve injuries are common, motor and sensory examination of the affected extremity is critical, with particular attention paid to strength grades (1–5) and sensation in the peroneal and tibial nerve distribution.
IMAGING AND OTHER DIAGNOSTIC STUDIES
The hip fracture-dislocation is first evaluated on the trauma anteroposterior (AP) pelvis radiograph (FIG 3A). The goal should be to emergently reduce the hip, and further imaging should not delay such treatment excessively.
Associated injuries such as femoral neck fractures, acetabular fractures, or pelvis fractures may require additional dedicated hip, Judet view, or pelvic inlet and outlet radiographs.
FIG 1 • The blood supply to the superior dome of the femoral head is primarily supplied by the medial femoral circumflex artery. It travels around the posterior aspect of the proximal femur, traveling deep to the quadratus femoris and penetrating the joint capsule just inferior to the piriformis tendon.
FIG 2 • Anterolateral femoral head impaction injury following anterior hip dislocation.
A fine-cut CT scan of the pelvis and femoral neck with coronal and sagittal reconstructions will further define the anatomy of the femoral head fracture and associated injuries (FIG 3B,C).
This should be obtained after reduction of the hip. A prereduction CT scan of the hip is not typically indicated.
Although MRI can be used to evaluate femoral head osteonecrosis in follow-up care, acute imaging has not been demonstrated to be prognostic of this complication.
DIFFERENTIAL DIAGNOSIS
Femoral head fractures typically are classified according to Pipkin (Table 1).
An isolated posterior wall fragment may be confused with a femoral head fracture.
NONOPERATIVE MANAGEMENT
Surgical management to reconstruct the articular surface usually is indicated.
Nonoperative management is used only in Pipkin type I fractures with small articular fragments with an associated concentric reduction of the hip.
FIG 3 • A. Preoperative AP radiograph demonstrating femoral head fracture. B,C Preoperative CT scans demonstrating femoral head fracture.
No quality clinical studies are available to define the amount of displacement of the fragment that can be tolerated. The accepted guideline is that the fragment should be congruent with the intact femoral head.
Small impaction injuries associated with anterior dislocation also may be treated nonoperatively in many cases.
Patients managed nonoperatively should remain toe-touch weight bearing for 8 to 12 weeks. For posterior dislocations, hip flexion beyond 70 degrees should be avoided for 6 weeks to protect the posterior capsule. Pool therapy can be initiated between 6 and 8 weeks.
SURGICAL MANAGEMENT
Most patients with femoral head fractures require surgery to provide an anatomic reduction of the femoral head, remove osteochondral loose bodies, or obtain a concentric reduction of the hip joint. Loose body removal can delay the onset of arthrosis.
Large, displaced fragments should be anatomically fixed. Smaller fragments inferior to the fovea can be excised if a quality, stable reduction of the fracture fragment cannot be obtained.
Hip arthroplasty is another good treatment option in elderly patients, especially with large head fragments. Femoral head fractures in this age group tend to have a large amount of associated articular cartilage damage and impaction of the bone at the fracture line, which compromises the patient's outcome.
Although their significance is unknown, labral tears often can be evaluated and treated surgically.
Algorithm for surgical management:
Nondisplaced fracture or small impaction injury
Nonoperative treatment
Displaced fragment
Small: surgical excision
Large: surgical fixation
Elderly patient
Small fragment with evidence of associated femoral head impaction: surgical excision
Large fragment or significant femoral head impaction: hip arthroplasty
Preoperative Planning
If the hip is dislocated, it should be emergently reduced under general anesthesia with skeletal relaxation.
Inadequate anesthesia during this reduction can lead to further damage to the articular surfaces of the femoral head and acetabulum as the hip is relocated.
If the hip is reduced, the patient should be placed in 30 pounds of longitudinal skeletal traction until formal open reduction and internal fixation of the femoral head occurs. Traction will unload the femoral head and prevent ongoing third-body wear within the hip joint.
Repeat radiographs and a post-reduction CT scan should be obtained to evaluate the hip joint.
It is reasonable at this point to delay definitive surgery until the appropriate surgeon, anesthesiologist, and equipment are available.
If the hip is irreducible, or there is an associated femoral neck fracture, emergent open reduction and internal fixation are required.
Positioning
For an anterior Smith-Peterson approach, the patient is positioned supine on a radiolucent table with a hip bump and the affected leg draped free.
For a posterior Kocher-Langenbeck approach, the patient is placed prone on a radiolucent fracture table with a distal femoral traction pin and the knee flexed to 90 degrees to relieve sciatic nerve tension.
For a Ganz surgical dislocation, the patient is placed on a radiolucent table with a beanbag in the lateral decubitus position and the affected leg draped free.
Approach
The most difficult decision is determination of the best operative approach.
Epstein2 originally argued that all femoral head fractures should be approached posteriorly, because the posterior blood supply to the femoral head had already been damaged during hip dislocation. This left the anterior capsular blood supply intact.
However, the anterior capsule and anterior femoral neck provide very little vascular supply to the femoral head. In addition, visualization of the anteriorly located femoral head fracture often is inadequate.
This approach is best used when large femoral head fragments remain dislocated posteriorly after reduction of the hip or with an associated posterior column or posterior wall fracture.
However, visualization of the anterior head fragment is difficult through a posterior approach, and such a fracture may be better treated with a surgical dislocation (see Techniques section).
Swiontkowski6 effectively demonstrated that better visualization of the femoral head was obtained for most Pipkin I and II femoral head fractures by using the distal limb of an anterior Smith-Peterson approach.
No increased incidence of osteonecrosis was seen, although a slightly higher risk of heterotopic ossification was observed.
A Smith-Peterson approach is currently the most commonly used method for fixation, and is the preferred approach for excision of the fragment.
The best visualization of the femoral head can be obtained through a surgical hip dislocation, as described by Ganz et al.3
This approach safely preserves the medial circumflex arterial supply to the femoral head.
It also allows the best access to associated injuries such as posterior acetabular fractures, labral tears, osteochondral debris, or posteriorly dislocated femoral head fragments.
Surgical dislocation also provides improved access to angulate lag screw fixation perpendicular to the femoral head fracture line.
TECHNIQUES
SMITH-PETERSON ANTERIOR APPROACH
Incision and Dissection
This is the preferred approach for fragment excision.
The patient is positioned supine on a radiolucent table with the leg draped free.
A vertical incision is made from the anterosuperior iliac spine extending distally toward the lateral border of the patella (TECH FIG 1A).
The sartorius and tensor fascia lata are identified (TECH FIG 1B). The fascia is incised over the medial aspect of the tensor muscle, and the medial border of the tensor muscle is followed to develop the interval between the tensor and sartorius muscles (TECH FIG 1C).
The tensor muscle is retracted laterally and the sartorius muscle medially.
The direct and indirect heads of the rectus femoris muscle are identified and are retracted medially (TECH FIG 1D). There is an overlying fascial layer that must be divided to be able to see this muscle. The lateral femoral circumflex vessel traverses the inferior part of the wound and marks the distal aspect of the incision.
TECH FIG 1 • A. Incision starts from the anterosuperior iliac spine extending distally toward the lateral border of the patella. B. The fascia is incised over the medial border of the tensor muscle. C. The medial border of the tensor muscle is followed to develop the interval between the tensor muscle and the sartorius muscle. D. The direct and indirect heads of the rectus femoris muscle are identified and retracted medially. E. The iliocapsularis muscle lies deep to the rectus muscle. This muscle is swept medially to expose the joint capsule.
In most patients, a residual muscle belly, the iliocapsularis muscle, is deep to the rectus muscle (TECH FIG 1E). This muscle is swept medially, exposing the capsule.
Capsulotomy
A longitudinal incision is made from the articular rim to the base of the femoral neck along the axis of the femoral neck. Anteriorly, a capsular incision is made along both the acetabular rim and the base of the femoral neck (TECH FIG 2A). Posteriorly, only a capsular incision along the articular rim is made.
Incising the capsule posteriorly along the base of the femoral neck places the medial femoral circumflex artery at risk. The medial femoral circumflex vessel, which rests in a synovial fold on the posterolateral femoral neck, and the acetabular labrum must be protected. The anterior aspect of the femoral neck is devoid of vascular structures.
If additional exposure is necessary, a portion of the direct head of the rectus muscle may be released.
Blunt retractors are placed within the joint capsule to obtain good exposure of the head fracture (TECH FIG 2B).
Fracture Reduction and Fixation
Reduction of fragment is facilitated by cutting the ligamentum teres.
The fragment is excised if it is too small for internal fixation.
A pointed reduction clamp is used to reduce the displaced fragment.
Many fractures have a component of impaction injury on the femoral head, so the fracture may not key in circumferentially. Circumferential visualization of the fracture is necessary to confirm that adequate reduction has been obtained.
In some cases, anterior dislocation of the femoral head will facilitate both fracture reduction and insertion of definitive fixation.
The fracture is fixed with recessed 3.5 or 2.7-mm lag screws or headless self-compressing screws (eg, Acutrack [Acumed LLC] or Herbert-Whipple screws [Zimmer Inc.]).
It is important to ascertain that the screw heads are recessed within the bone.
Ganz Surgical Dislocation
The patient is in the lateral position.
Either a direct lateral incision or a traditional posterolateral approach is used.
The gluteus maximus is retracted posteriorly and the tensor fascia lata anteriorly.
The interval between the gluteus minimus and the piriformis is identified, and the gluteus minimus is sharply elevated anteriorly.
The trochanter is osteotomized, leaving a portion of the tip of the trochanter intact to protect the medial femoral circumflex vessel. The osteotomy is oriented parallel to the shaft of the femur (TECH FIG 3A).
The gluteus minimus and medius, the trochanteric fragment, and the vastus lateralis and intermedius muscles are sharply elevated anteriorly.
The dissection is kept superior to the piriformis muscle, because the medial femoral circumflex vessel penetrates the hip capsule at the inferior margin of the piriformis.
TECH FIG 2 • A. A capsulotomy is performed by making a longitudinal incision from the articular rim to the base of the femoral neck along the axis of the femoral neck. Anteriorly, a capsular incision is made along both the acetabular rim and the base of the femoral neck. Posteriorly, only a capsular incision is made along the articular rim. B. After the capsulotomy is performed, blunt retractors are placed around the femoral neck to expose the femoral head and neck.
TECH FIG 3 • A. The trochanteric osteotomy is made parallel to the shaft of the femur. B. Z-shaped capsulotomy. C–E. Intraoperative views following surgical dislocation of the hip. The ligamentum teres was transected to improve exposure, but the medial retinaculum was left intact. The fragment is fixed with three headless screws. Note the area of femoral head bone loss due to impaction. F,G.Posterosuperior labral tear is demonstrated. The labrum is reduced and secured with suture anchors. Surgical dislocation provides the best exposure of the acetabulum and is our preferred exposure for this fracture pattern. H. Postoperative radiograph. The trochanteric fragment is stabilized with two or three 3.5-mm cortical screws directed in a cephalad to caudad direction.
Placing the leg in the figure 4 position with the operative-side foot on the table improves exposure of the anterior capsule.
A Z-shaped capsulotomy is performed with the cephalad limb posterior and the caudad limb anterior (TECH FIG 3B).
The femoral head is dislocated anteriorly.
The femoral head fragment is reduced or excised. The labrum is assessed, and is fixed with suture anchors if it is torn (TECH FIG 3C–H).
If an associated posterior wall fragment is present, the hip is reduced and the wall fragment repaired.
The capsule is loosely repaired, and the trochanter is reattached with two or three 3.5-mm cortical screws.
POSTOPERATIVE CARE
Patients are given 24 hours of appropriate antibiotic prophylaxis.
Deep venous thrombosis prophylaxis is started 24 hours postoperatively, and is used before surgery if it has been delayed more than 24 hours after injury.
Heterotopic ossification prophylaxis using either 700 cGy of radiation or indomethacin 25 mg three times daily is considered in patients with significant damage to the gluteus minimus muscle.
Patients are allowed 30 to 40 pounds weight bearing for 8 to 12 weeks, then progressed to full weight bearing as tolerated.
Hip flexion is limited to 70 degrees for 6 weeks.
Pool therapy is started once the incision is dry and the sutures are removed.
Once weight bearing is initiated at 12 weeks, more aggressive physical therapy focusing on gait training and quadriceps and hip abductor strengthening is started.
OUTCOMES
Because of the rarity of femoral head fracture-dislocations, no large prospective trials have compared surgical versus nonsurgical treatment methods.
Most retrospective reviews, including those by both Epstein2 and Jacob,4 report less than 50% good or excellent results at 5 to 10 years of follow-up.
Posttraumatic arthrosis is common following a femoral head fracture, and patients should be warned early of the poor prognosis.
COMPLICATIONS
Posttraumatic arthrosis: >50%
Femoral head osteonecrosis: 20%
Neurologic injury: 10% (60% of these recover some function)
Heterotopic ossification: 25% to 65%; higher risk with anterior approach
Hip instability
Deep venous thrombosis
REFERENCES
1. Asghar FA, Karunakar MA. Femoral head fractures: diagnosis, management, and complication. Orthop Clin North Am 2004;35: 463–472.
2. Epstein HC, Wiss DA, Cozen L. Posterior fracture dislocation of the hip with fracture of the femoral head. Clin Orthop Rel Res 1985;201:9–17.
3. Ganz R, Gill TJ, Gautier E, et al. Surgical dislocation of the adult hip: A technique with full access to the femoral head and acetabulum without risk of avascular necrosis. J Bone Joint Surg Br 2001; 83B:1119–1124.
4. Jacob JR, Rao JP, Ciccarelli C. Traumatic dislocation and fracture dislocation of the hip: A long-term follow-up study. Clin Orthop Relat Res 1987;214:249–263.
5. Seibenrock KA, Gautier E, Woo AK, Ganz R. Surgical dislocation of the femoral head for joint debridement and accurate reduction of fractures of the acetabulum. J Orthop Trauma 2002; 16:543–552.
6. Swiontkowski MF, Thorpe M, Seiler JG, Hansen ST. Operative management of displaced femoral head fractures: case matched comparison of anterior versus posterior approaches for Pipkin I and Pipkin II fractures. J Orthop Trauma 1992;6:437–442.