➢ Femoral head fractures are associated with hip dislocations and are relatively uncommon.
➢ The goals of initial treatment are to identify associated life-threatening injuries and to achieve prompt reduction.
➢ Operative treatment of femoral head fractures is commonly performed through a direct anterior approach or surgical hip dislocation, depending on associated injury patterns, and with mini-fragment lag-screw fixation.
➢ Careful surgical technique and anatomic reduction can minimize the risk of osteonecrosis. Heterotopic ossification is a common finding after the use of a direct anterior approach but is rarely symptomatic.
Femoral head fractures are consequential but uncommon injuries. Because of their relatively rare occurrence, large series with validated outcomes have not been published, to our knowledge. However, the available literature provides important insights into the treatment of these challenging fractures. Understanding the anatomy, injury mechanism, and principles of treatment are essential for providing sound care and maximizing the chance of a good outcome.
The osseous anatomy and supporting soft tissues of the hip create an inherently stable articulation. The femoral head is deeply seated within the acetabulum; the surrounding fibrocartilaginous labrum further contributes to stability. The capsuloligamentous structures (iliofemoral, ischiofemoral, and pubofemoral ligaments) are also important stabilizers of the hip.
The intra-osseous and extra-osseous blood supply of the femoral head can be disrupted following a fracture-dislocation of, or during an operative approach to, the hip. The primary intra-osseous blood supply to the weight-bearing surface of the femoral head is from the deep branch of the medial femoral circumflex artery1-3. The medial femoral circumflex artery has two major branches, the superior and inferior retinacular arteries, although reports of the constancy of inferior retinacular branches vary2,4. The medial epiphyseal artery usually supplies the perifoveal region of the head1, and contributions from the lateral femoral circumflex artery are minimal and inconstant1,3.
Femoral head fractures are associated with high-energy trauma (e.g., motor-vehicle collision5) and typically occur in association with a posterior hip dislocation. They occur more commonly in men than women5. A fracture also may occur in association with an anterior hip dislocation, but these fractures are less common and typically are impaction fractures6. Giannoudis et al., in a recent systematic review, reported a femoral head fracture in 127 (11.7%) of 1082 hip dislocations5.
A thorough history and musculoskeletal examination are critical in order to identify other important injuries. A thorough visual inspection may reveal skin lesions and may give clues to the nature of the injury. Patients who have sustained a dislocation or fracture-dislocation of the hip classically present with a shortened, flexed, and internally rotated lower extremity when the hip remains dislocated. This position of the lower limb is not present in all cases, and its absence does not exclude hip injury. A systematic neurovascular examination should be performed, with special attention being paid to terminal motor and sensory function of the tibial and peroneal divisions of the sciatic nerve7. Last, the ipsilateral knee must be assessed for stability, given the association between hip dislocations and ligamentous knee injuries.
After a standard trauma evaluation8, radiographic evaluation should begin with an anteroposterior pelvic radiograph. Critical evaluation will reveal the presence of a hip dislocation, the femoral head fragment (which is often retained in the acetabulum), and any associated femoral neck or acetabular fractures. Oblique Judet radiographs will aid in the evaluation of an associated acetabular fracture, and the obturator oblique view may bring the plane of the femoral head fracture in line with the x-ray beam9. A hip series consisting of anteroposterior and cross-table lateral radiographs should also be evaluated.
Computed tomography (CT) scanning should be performed after reduction of the hip dislocation to assess the adequacy of reduction and to aid in operative planning. The CT scan provides valuable information about the congruency of the hip joint, the presence of debris between the femoral head and the acetabulum, the size and orientation of the femoral head fragment, and the presence of even very small posterior wall acetabular fractures. Magnetic resonance imaging (MRI) is not routinely performed in the acute setting as it is of limited prognostic value and does not alter early treatment10.
The obturator oblique radiograph is also useful during the follow-up period to accurately determine the accuracy of reduction and to visualize the healing fracture. The CT scan can be used to determine the appropriate amount of rotation to bring the fracture plane parallel to the x-ray beam9.
Several classification systems have been described for femoral head fractures. The Pipkin11 system is the most commonly used and subdivides Stewart and Milford type-IV12 posterior hip dislocations into four categories (Table I, Fig. 1)11. Pipkin made the distinction between infrafoveal and suprafoveal fractures of the femoral head and the presence of associated femoral neck or acetabular fractures.
The system described by Brumback et al. can be globally applied to all fracture-dislocations of the femoral head (Table II)13. This system accounts for the direction of hip dislocation, stability of the joint after reduction, and location of femoral head fracture.
In the AO/OTA classification system, femoral head fractures are categorized as 31-C14. The classic shear pattern associated with posterior hip dislocation is classified as 31-C1, whereas an osteochondral impaction fracture associated with an anterior dislocation is classified as 31-C214. Combined femoral neck and head fractures are classified as 31-C3. Other eponymous classification systems have been proposed but are not widely used15,16.
Initial patient management follows Advanced Trauma Life Support (ATLS)17 protocols. If a hip dislocation is present, urgent closed reduction is performed in conjunction with chemical skeletal relaxation to decrease the risk of hip osteonecrosis18,19. If the hip is successfully reduced, a post-reduction radiograph of the pelvis is made to confirm reduction, followed by a CT scan. If the hip is unstable or if osteochondral debris is interposed, skeletal traction should be utilized to maintain reduction and to minimize articular damage.
In some cases, closed manipulative reduction of a hip fracture-dislocation cannot be performed20. This scenario occurs rarely but must be recognized in order to minimize the number of reduction attempts and the risk of further iatrogenic hip injury. Clinically, these patients have the hip positioned in a slightly flexed position in neutral rotation with an obvious limb-length discrepancy. In addition, the hip demonstrates immobility that is unlike the passive motion encountered in a standard dislocated hip. Radiographically, the cancellous surface of the proximal part of the femur is intimately apposed to the lateral cortical iliac bone of the supra-acetabular region (Fig. 2). Open reduction and internal fixation (ORIF) of an irreducible femoral head fracture-dislocation should be performed in a timely manner. Irreducible fracture-dislocations also can occur in the setting of an acetabular fracture. In this pattern, the operative approach is dictated by the injury and the operative plan.
The treatment of femoral head fractures is determined by the size and location of the fracture, the congruency of the reduced hip joint, and the presence of associated injuries. Treatment options include nonoperative treatment, fragment excision, internal fixation, and arthroplasty5,21-29. Nonoperative treatment is generally reserved for patients with infrafoveal fractures with a concentric hip joint and no intra-articular debris and patients in whom operative intervention carries a marked risk of complications. In a systematic review, nonoperative treatment was prescribed for 25% of seventy-nine Pipkin type-I fractures but only 15% of all other Pipkin types5. Patients receiving nonoperative treatment should begin a toe-touch weight-bearing protocol for six weeks with early active range of motion while avoiding positions that place the patient at risk for repeat dislocation. With time, the patient may begin a progressive partial weight-bearing program and wean off assistive devices.
The timing of operative intervention for femoral head fractures remains controversial. A recent randomized controlled trial demonstrated significantly worse outcomes for patients who had closed manipulative reduction and delayed ORIF compared with those who received immediate operative reduction and fixation (p < 0.05)30. However, concentric reduction was not achieved in all of the patients in the delayed treatment group, and the final outcome was more associated with the accuracy of the final reduction. Other studies have shown no correlation between the timing of fixation and outcome, assuming that a prompt closed manipulative reduction is achieved19,31.
Fragment excision is mostly commonly performed for Pipkin type-I fractures or for fractures that are too comminuted to allow accurate reduction and/or stable fixation5,27,32. Every attempt should be made to preserve fragments in the weight-bearing surface of the femoral head. ORIF should be performed for fractures involving the weight-bearing surface, larger Pipkin type-I fractures, and fractures associated with other osseous injuries. The majority of femoral head fractures are treated with ORIF, which is true for each Pipkin subtype as well5 (Fig. 3).
Because of the highly constrained nature of the hip joint, the fixed femoral head is relatively protected from shear forces. Therefore, mini-fragment fixation with 2.0 or 2.4-mm screws is sufficient to secure the fracture until union27. The screws should be placed in lag fashion and may be predrilled. Some authors have advocated the use of headless variable-pitch screws or bioabsorbable implants33,34.
Fragment excision and ORIF generally are carried out through the Smith-Petersen or modified Hueter direct anterior approach23,32. Tenotomy of the rectus femoris can be performed to facilitate dislocation and reduction of the hip and exposure of the fracture. The hip is dislocated anteriorly with adduction and extension, followed by the placement of the leg in a “figure-4” position for cleaning and fracture fixation and then by a gentle manipulative reduction. These direct anterior approaches are also useful for reduction of the femoral neck in patients with Pipkin type-III fractures, although an accessory incision is necessary for implant placement. The use of hip arthroscopy for excision or internal fixation has also been described, but the literature is limited to small case series at this time35-37.
Surgical hip dislocation has been described for fragment excision or ORIF5,24,25,28. This approach may be particularly useful for patients with Pipkin type-IV fractures, especially those with isolated posterior wall or posterior column fractures of the acetabulum. The surgical technique was described by Ganz et al.38 and affords visualization of the entire femoral head, acetabulum, and acetabular labrum as well as the majority of the capsule.
The Kocher-Langenbeck approach, although familiar to most surgeons, is less useful for femoral head fractures5. This posterior approach limits access to an anteroinferior femoral head fracture and has been associated with high complication rates in several series5,25,29. Treatment of other Pipkin type-IV fractures should be carefully considered to formulate a treatment plan that will allow accurate reduction and stabilization of both the acetabular and femoral head fractures.
A final critical component of any operative intervention is an assessment of stability. Femoral head fractures amenable to ORIF through a direct anterior approach commonly are associated with small fractures off the acetabular rim. A fluoroscopic stress examination after fixation in the operating room will reveal any occult instability and permit ORIF of the fracture or repair of the capsulolabral injury through a separate approach.
Arthroplasty is a useful treatment option in select cases. Patients who have preexisting degenerative joint disease or who cannot tolerate a modified weight-bearing protocol may particularly benefit from primary hip arthroplasty. Arthroplasty is most commonly performed for the treatment of Pipkin type-III fractures, with a rate approaching 39% in one review of eighteen cases5.
Functional outcomes following hip fracture-dislocations and femoral head fractures have been reported in many series. Thompson and Epstein provided a functional assessment tool for patients following hip dislocation in their landmark review of >200 cases39. Pipkin, in his report of twenty-five hip dislocations with associated femoral head fractures, commented that the nature of the injury precludes any results from being graded as excellent on the basis of the standards outlined by Thompson and Epstein11. Epstein et al.18,40 reported improved results following primary open hip reduction in patients with a hip dislocation and femoral head fracture. In the authors’ series, only four of forty-six patients were managed with ORIF of the femoral head. The primary goals of open reduction were to remove loose fragments, to restore stability to the hip joint, and to ensure concentric hip reduction.
Marchetti et al. reported on thirty-three patients with a femoral head fracture41. Thirty-one patients (94%) were managed with ORIF or fragment excision. There was no significant difference between operative and nonoperative treatment or between ORIF and fragment excision. The authors reported a 67% rate of good results across all Pipkin subtypes; however, patients with a Pipkin type-I or II injury had a significantly (p < 0.02) better functional outcome compared with patients with a Pipkin type-III or IV injury. Stannard et al. evaluated twenty-six patients following femoral head fracture31. The authors used the Short Form-12 (SF-12) to report functional outcomes. The duration of follow-up ranged from six to fifty-one months, and functional outcome data were available for seventeen patients. Patients with a Pipkin type-II fracture had a significantly lower physical component summary score than patients with a type-I (p = 0.04) or type-IV (p = 0.02) fracture. No difference was seen with regard to surgical approach (anterior versus posterior) or surgical treatment (fragment excision versus fixation). Golisky et al. presented functional data on twenty-five patients with a femoral head fracture22. The average duration of follow-up was 41.4 months. The authors used the SF-36 and Musculoskeletal Function Assessment (MFA) measures and reported that age (p = 0.026), anterior surgical approach (p = 0.024), and ipsilateral acetabular fracture correlated significantly with poorer physical function (p = 0.069, with the level of significance set at p < 0.1).
A systematic review of studies evaluating femoral head fractures identified eighteen articles in which the Thompson-Epstein score was used as a functional assessment tool5. The authors found no significant difference in functional outcome score between Pipkin fracture types or between treatment methods (nonoperative, fragment excision, ORIF, and arthroplasty). The authors noted a near-significant (p = 0.057) difference in functional outcome when Pipkin type-I and II fractures were compared with Pipkin type-III and IV fractures, regardless of treatment.
Multiple small series have evaluated the effect of surgical approach25,28,29,42 and the use of ORIF as opposed to fragment excision11,19,21,31,40 on the functional outcome of surgically treated femoral head fractures. Unfortunately, drawing meaningful conclusions is difficult because of the small size of the cohorts and the lack of viable comparison data. Larger prospective studies involving the use of validated functional outcome scores and current management techniques are needed to clarify injury and treatment factors that affect functional outcome.
The rate of osteonecrosis following femoral head fracture has been reported to be as high as 24% (eleven of forty-six) following both operative and nonoperative treatment of these injuries18. The development of osteonecrosis following femoral head fracture is likely multifactorial. The initial injury imparts trauma to the proximal femoral blood supply, cartilage, and subchondral bone. These components are independent of the treating physician. Surgeon-controlled factors include intraoperative preservation of the proximal femoral blood supply as well as anatomic fracture and joint reduction with rigid internal fixation.
In a recent systematic review, the overall prevalence of osteonecrosis was reported to be 11.9% (forty-eight of 405)5. Surgical approach has been implicated in the development of osteonecrosis. Despite the early belief that an anterior surgical approach would compromise the only remaining blood supply to the proximal part of the femur18 following a posterior femoral head fracture-dislocation, multiple studies have shown an anterior approach to be safe and effective for these fractures20,22,27,29. Stannard et al. noted that four of the five patients in their series who had osteonecrosis at the time of the latest follow-up had been managed through a posterior approach31. This difference did not reach significance (p = 0.3), but the odds ratio revealed a 3.2 times higher rate of osteonecrosis when a posterior approach was used. Swiontkowski et al. reported that the rate of development of osteonecrosis was 16.7% (two of twelve) among patients in whom operative treatment had been performed through a posterior approach, compared with 0% among those in whom it had been performed through an anterior approach29. Giannoudis et al. reported that the risk of osteonecrosis was 3.67 and 2.24 times higher when the posterior approach was used compared with the anterior approach and surgical dislocation, respectively; these differences were not significant5.
Heterotopic ossification following the surgical treatment of femoral head fractures is common. In some studies, the rate has been reported to be as high as 90% (nineteen of twenty-one)26. In the systematic review by Giannoudis et al., heterotopic ossification of any grade was noted in 16.8% of 405 patients5. Time to hip reduction, surgical approach, injury type, and associated clinical conditions (e.g., neurological injury) may influence the formation of heterotopic ossification.
Marchetti et al. noted that heterotopic ossification developed in seven (88%) of eight patients who underwent hip reduction more than six hours after injury, compared with fourteen (58%) of twenty-four who underwent hip reduction less than six hours after injury41. This difference was not significant. Swiontkowski et al. noted a marked increase in clinically relevant heterotopic ossification in patients who underwent treatment through a Smith-Petersen approach compared with the Kocher-Langenbeck approach29. The trochanteric flip osteotomy has been associated with increased rates of heterotopic ossification. Giannoudis et al. reported a 1.87 times higher rate of heterotopic ossification following surgical hip dislocation, but this finding was not significant (p > 0.05)5. Increased rates of heterotopic ossification have been described after Pipkin type-III and IV injuries41. Although heterotopic ossification is common following femoral head fractures, the clinical relevance is variable and surgical excision is rarely necessary27.
Femoral head fractures are uncommon but severe injuries. After prompt closed reduction of associated hip dislocations, a thorough evaluation is required to detect all associated injuries and to formulate an appropriate treatment plan. Treatment should be directed toward achieving a stable, concentrically reduced hip joint with anatomic reduction of the fracture or excision of comminution and removal of articular debris. Arthroplasty is reserved for older patients, patients with degenerative changes of the hip, and patients with highly complex injuries. The development of osteonecrosis leads to worse outcomes and to secondary procedures. The presence of heterotopic ossification does not necessarily require additional intervention.
Source of Funding: Neither the authors nor their institutions received any funding related to this manuscript.
Investigation performed at the University of Southern California, Los Angeles, California
Disclosure: None of the authors received payments or services, either directly or indirectly (i.e., via his or her institution), from a third party in support of any aspect of this work. None of the authors, or their institution(s), have had any financial relationship, in the thirty-six months prior to submission of this work, with any entity in the biomedical arena that could be perceived to influence or have the potential to influence what is written in this work. Also, no author has had any other relationships, or has engaged in any other activities, that could be perceived to influence or have the potential to influence what is written in this work. The complete Disclosures of Potential Conflicts of Interest submitted by authors are always provided with the online version of the article.
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