Periprosthetic Hip Fracture Case File

Periprosthetic Hip Fracture Case File

Eugene C. Toy, MD, Andrew J. Rosenbaum, MD, Timothy T. Roberts, MD, Joshua S. Dines, MD

CASE 6

A 61-year-old woman with a previous right total hip replacement presented with severe left hip osteoarthritis and underwent a left total hip replacement. The patient was doing well and walking pain-free, when at 4 months postoperatively, she tripped while stepping off a curb and landed directly onto her left side. She did not lose consciousness and only complained of left hip and groin pain and was not able to ambulate after the fall. She was taken to the emergency department for evaluation. Her past medical history is noncontributory, and her surgical history is as previously noted. Findings on physical exam include pain with axial loading and internal/external rotation of the left hip. Her skin is intact, and she has good sensation to light touch and motor function through the L4-S1 distribution. She does not have any tenderness to palpation around the knee or distally. She has 2+ dorsalis pedis and posterior tibial pulses. An anteroposterior (AP) radiograph of the left hip is obtained ( Figure 6–1 ).

Figure 6–1. AP radiograph of the left hip demonstrating a periprosthetic femur fracture.

► What is the most likely diagnosis?

► What other aspects must be considered before determining the appropriate treatment for this patient?

► What is the most appropriate treatment for this patient?

ANSWER TO CASE 6:

Periprosthetic Hip Fracture                              

Summary: A 61-year-old woman with a recent left total hip replacement sustained a fall and injury to her left hip. Plain films of the left hip show a periprosthetic femur fracture.

• Most likely diagnosis: Left periprosthetic femur fracture.
• Additional considerations: After identifying the fracture pattern and location, the 2 most important aspects to consider are the stability of the prosthetic femoral stem and the quality of the remaining bone stock.
• Best treatment: Revision of the femoral component to a cementless, porous coated long stem that bypasses the fracture by at least 2 cortical diameters. Fracture fixation is also required with cables, a plate, and/or strut graft.

ANALYSIS

Objectives

1. Understand what to look for on radiographs in the setting of a periprosthetic fracture, including fracture location, prosthesis fit, and bone stock.
2. Understand the Vancouver classification system of periprosthetic hip fractures and how it can be used to guide the appropriate method of treatment.
3. Be familiar with the basic treatment options for periprosthetic hip fractures.
4. Recognize potential complications arising from their treatment.

Considerations

This patient is a 61-year-old woman who sustained a fall and a left periprosthetic femur fracture. Although the patient presented complaining of left hip pain and sustained no other obvious injuries, it is important to rule out concomitant injuries, including head trauma or other musculoskeletal injuries. A thorough neurovascular examination of the left lower extremity, including sensory, and vascular assessments of the foot and ankle is mandatory. Movement of the hip, quadriceps, and hamstring may be limited as a result of pain, but a thorough assessment of the distal musculature should be performed. In addition, key questions regarding the patient’s functional status before the fall may provide valuable insight: Was the patient able to ambulate without assistance? Did the patient have any thigh pain before the fall (which may indicate the presence of an already loose femoral component)?

Given the patient’s inability to ambulate, she should be admitted to the hospital for definitive management of her fracture. An appropriate medical workup should be performed, including a chest x-ray, electrocardiogram, and laboratory tests before proceeding to the operating room. The medical team performing risk stratification of the surgery should understand that revision surgery will likely require a prolonged operative time and increased blood loss versus a primary, elective total hip arthroplasty. The orthopaedic team must preoperatively plan the surgical procedure and ensure that all implants and options that may be used are readily available. Most important, the patient must understand that in revision hip surgery, both the rates of postoperative dislocation and infection are increased compared with primary hip surgery.

APPROACH TO:

Periprosthetic Hip Fracture                                             

DEFINITIONS

PERIPROSTHETIC FRACTURE: A break in the bone surrounding a joint replacement prosthesis.

POROUS COATING: In total hip replacement, cementless implants commonly have a region where the surface is covered in microscopic pores, which enhances bone ingrowth for implant fixation.

SUBSIDENCE: In the setting of a total hip replacement, refers to the femoral stem migrating distally after initial implantation, indicating a high likelihood of a loose stem.

CLINICAL APPROACH

Etiologies

As the number of patients in the population living with a total hip arthroplasty continues to rise, the incidence of periprosthetic fractures also continues to increase. Patients with total hip replacements span a wide age range, with elderly patients being at increased risk for low energy falls, whereas younger, more active patients may be at risk for higher energy trauma. The Mayo Clinic Joint Replacement Database reported the largest series of periprosthetic hip fractures and noted an incidence of 1% (238 of 23,980) in primary hip arthroplasties and 4% (252 of 6349)

in revision hip arthroplasties, although the overall incidence has been reported to be as high as 18%. Periprosthetic hip fractures can occur both intraoperatively and postoperatively, and it is key to accurately classify these fractures to determine the appropriate treatment plan. The most critical consideration is to determine the stability of the implant, as simple fixation of a fracture surrounding a loose femoral stem is likely to fail as a result of implant subsidence.

    Risk factors for periprosthetic hip fractures are similar to those of the general population. In the elderly, low-energy falls, particularly in the setting of osteoporosis or inflammatory arthropathy, can lead to periprosthetic fractures. Another consideration pertains to the type of femoral component fixation and the use of either a proximally or fully-porous coated implant. Currently, the majority of femoral stems in primary total hip arthroplasty are implanted using cementless fixation, in which the femoral stem has a proximal porous coating, allowing bony ingrowth and fixation at the proximal aspect of the stem. This enables the stress from weightbearing to be transferred from the femoral head, through the proximal bone and calcar of the femur, and then distally through the native femoral shaft. With these wedge-fit tapered designs, proximal fractures may occur. With cylindrical fully-porous coated stems, distal “split” fractures can occur.

Clinical Presentation

Patients typically present with a low-energy mechanism of injury, such as a fall from standing, and have pain in the hip and femur, with or without the ability to ambulate. It is key to determine any other sites of injury, including head trauma, and whether or not the patient had any shortness of breath, lightheadedness, dizziness, or symptoms indicating a cardiac or neurologic cause of their injury. Any symptoms in the lower extremity before the injury should also be noted, along with signs of start-up thigh pain (pain initiated with ambulation on rising from a chair) that may indicate a loose femoral stem.

    Prior surgical records and reports should be obtained to determine the prior surgical approach, implant type and size, and any perioperative complications including infection. The presence of prior infection should raise concerns of an active infection, and further testing should be performed to rule out infection such as hip aspiration, or cultures obtained intraoperatively. Of note, normal laboratory markers for occult infection such as the erythrocyte sedimentation rate and C-reactive protein can be falsely positive in the setting of a fracture and thus are of limited utility. As always, a thorough medical history should be obtained. A detailed examination of the affected lower extremity, including a complete neurovascular examination, and assessment of prior incisions and skin integrity should be performed. In addition, any leg length discrepancy should also be noted to assist with preoperative planning.

Diagnosis

The diagnosis of a periprosthetic hip fracture can typically be made using standard radiographs. Radiographs should include an AP of the pelvis, AP and lateral of the hip, and AP and lateral of the femur. Visualization of the entire femur is critical to assess the presence and distal extent of the fracture. To determine the stability of the implant, comparison to prior radiographs is useful to assess any increase in periprosthetic bone loss or implant subsidence that may suggest component loosening. With cementless femoral implants, the point at which the metal stem narrows proximally to become the femoral neck is typically aligned with the proximal, medial aspect of the native femur. If this point on the femoral stem migrates distally (or a fracture causes the medial aspect of the native femur to migrate proximally or displace), then the femoral stem is loose and needs to be revised. It is critical to assess both the acetabular and femoral components for both position and signs of loosening, as signs of acetabular loosening may warrant revision of the acetabular component during concomitant fixation of the femur fracture. Ultrasound, computed tomography, and magnetic resonance imaging are not routinely required.

TREATMENT

The treatment of a periprosthetic hip fracture is guided by the Vancouver classification system ( Table 6–1 ). Type A fractures include fractures of the greater trochanter (AG) and lesser trochanter (AL). Greater trochanter fractures are stable when minimally displaced, but may require surgical treatment with a plate if displaced proximally. Lesser trochanter fractures can often be treated nonoperatively. However, if a significant portion of the calcar is involved, leading to destabilization of the stem, then revision of the femoral stem with fixation of the calcar/lesser trochanter with cables or supplementary plate fixation surrounding the greater trochanter is required.

    Type B fractures occur around or just below the tip of the femoral stem. A B1 fracture occurs around a well-fixed stem and can be treated with plates and screws and possibly cortical strut allografts and cables. A B2 fracture occurs around or just below an unstable stem, and thus revision of the femoral stem is required. Typically, long porous-coated cementless stems are used to bypass the fracture and to achieve distal fixation. In addition, the fracture fragment is fixed using plates, cables, or cortical strut allografts. A B3 fracture is distinguished from a B2 fracture, as B3 fractures possess insufficient bone stock. Therefore, B3 fractures are also treated with femoral component revision and fracture fixation, but often require special techniques such as bone grafting or implantation of a proximal femoral replacement.

    Type C fractures occur well below the femoral prosthesis and thus are treated with fixation of the fracture itself, without revision of the femoral or acetabular components.

Complications

Complications after the treatment of periprosthetic hip fractures include failure of the fracture to heal appropriately (nonunion), failure of femoral stem fixation (commonly owing to misdiagnosis of the initial stability of the stem), infection, dislocation, thromboembolic complications, and medical morbidity and mortality related to the surgical treatment itself.

COMPREHENSION QUESTIONS

6.1 An 82-year-old man with a history of a prior left hip fracture treated with a bipolar hemiarthroplasty was in his usual state of health when he sustained another fall onto his left hip. He is neurovascularly intact and complains only of left hip pain. An AP left hip radiograph was taken and is shown in Figure 6–2 . According to the Vancouver classification system, what type of periprosthetic fracture has this patient suffered?

Figure 6–2. AP radiograph of the left hip demonstrating a periprosthetic femur fracture surrounding a

bipolar hemiarthroplasty.

A. Type AL

B. Type AG

C. Type B1

D. Type B2

E. Type C

6.2 A 75-year-old woman who is 2 years removed from a right total hip arthroplasty sustains a fall and a nondisplaced greater trochanter fracture. The femoral stem appears stable on both anteroposterior and lateral radiographs of the hip and femur. Which of the following is the most appropriate treatment?

A. Open reduction and internal fixation of the fracture using a greater trochanter plate and cables

B. Resume all activities as tolerated, with no restrictions

C. Weightbearing as tolerated, but with no passive adduction past midline and no active abduction of the lower extremity

D. Nonweightbearing to the right lower extremity

6.3 A 79-year-old woman undergoes successful treatment of a Vancouver B2 periprosthetic femur fracture with a long porous-coated cementless stem, cables, and a cortical strut allograft. Which of the following complications is she at an increased risk for as compared with those patients who have undergone primary total hip arthroplasty?

A. Infection

B. Dislocation

C. Deep vein thrombosis

D. A and B

E. A, B, and C

ANSWERS

6.1 C. This patient sustained a periprosthetic left femur fracture. Because the stem appears stable proximally with no fracture extending proximally and no radiolucency surrounding the stem, this is likely a Vancouver B1 fracture. Vancouver B2 fractures would be similarly at the tip of the prosthesis, but would involve a loosened stem. Vancouver A fractures involve 1 of the 2 trochanters. Type C fractures occur distal to the prosthesis.

6.2 C. This patient sustained a nondisplaced greater trochanter fracture (AG) and thus should initially be treated conservatively. The patient can continue to be weightbearing as tolerated, but should observe hip abduction precautions (movements that may cause the greater trochanter fracture to displace). The patient should receive sequential radiographs, and if the fracture demonstrates worsening displacement, then open reduction internal fixation of the fracture can be considered.

6.3 E. Revision hip surgery, particularly in the setting of a periprosthetic fracture, is extremely challenging. Unfortunately, the results are often less satisfactory than those seen with elective primary hip replacement. Postoperative complications occur more frequently in this setting and include infection, dislocation, and deep vein thrombosis, in addition to nerve palsy, cortical perforation, and fracture.

    CLINICAL PEARLS    

► The incidence of periprosthetic hip fractures continues to rise as a result of the increasing number of patients in the population with total hip arthroplasties. ► Radiographs of the entire femur must be obtained to assess the presence and entire extent of the fracture, along with stability of the femoral stem. ► Key aspects to consider regarding the classification and treatment of periprosthetic hip fractures are the stability of the femoral stem and the quality of the remaining bone stock. ► If the femoral stem is suspected to be unstable or loose, revision of the femoral stem should be performed, as fixation of a fracture in the setting of a loose femoral stem often leads to fracture nonunion and implant failure.

REFERENCES

Berry DJ. Epidemiology: hip and knee. Orthop Clin North Am. 1999;30:183-190. 

Brady OH, Garbuz DS, Masri BA, et al. Classification of the hip. Orthop Clin North Am. 1999;30: 215-220. 

Duncan CP, Masri BA. Fractures of the femur after hip replacement. Instr Course Lect. 1995;44: 293-304. 

Pike J, Davidson D, Garbuz D. Principles of treatment for periprosthetic femoral shaft fractures around well-fixed total hip arthroplasty. J Am Acad Orthop Surg. 2009;17:677-688.

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