Periprosthetic Fractures Around Total Hip and Knee Replacements

Periprosthetic fractures are breaks in the bone that occur around or near a joint replacement implant. These fractures present a growing concern in orthopedics, with an increasing incidence attributed to factors such as the rising number of joint replacement surgeries performed each year and the aging population1. This article offers a comprehensive overview of periprosthetic fractures around total hip and knee replacements, encompassing their incidence, management, classification, surgical techniques, and implant options.

Incidence of Periprosthetic Fractures

The incidence of periprosthetic fractures can vary based on factors like the type of joint replacement, patient age, bone quality, and implant type. The increasing number of primary total hip arthroplasties performed is expected to lead to a rise in the incidence of periprosthetic fractures around the femoral stem2.

Total Hip Replacements

  1. Intraoperative fractures occur in 3.5% of primary uncemented hip replacements and 0.4% of cemented arthroplasties3. The mechanism of these fractures typically involves impaction of the acetabular component during surgery3.
  2. Postoperative fractures occur in 0.1% of primary THAs, most commonly at the stem tip3.
  3. The 20-year fracture probability is 3.5% for primary THA and 11% for revision THA4.
  4. The incidence of periprosthetic fractures needing surgery is 0.92 per 1,000 prosthesis years. This incidence is higher in patients over 70 years old at the time of primary THR and for patients who underwent THR for a hip fracture5.
  5. In revision hip replacement, the rate of periprosthetic fracture was three times higher with uncemented stems4.
  6. Increased use of cementless acetabular cups is predicted to increase the occurrence of future periprosthetic fractures of the acetabulum after THA4.

Several risk factors can contribute to periprosthetic femoral fractures after THA, including:

  1. Impaction bone grafting
  2. Female gender
  3. Technical errors during surgery
  4. Cementless implants
  5. Osteoporosis
  6. Revision surgery
  7. Minimally invasive techniques (controversial) 3

The etiology of these fractures can differ depending on the timing of their occurrence:

  1. Early postoperative fractures (within the first six months): Cementless prostheses tend to fracture early, likely due to stress risers created during reaming and broaching. Wedge-fit tapered designs are associated with proximal fractures, while cylindrical fully porous-coated stems tend to cause a distal split in the femoral shaft3.
  2. Late postoperative fractures (typically after 5 years): Cemented prostheses tend to fracture later, usually around the tip of the prosthesis or distal to it3.

Total Knee Replacements

  1. The incidence of femoral periprosthetic fractures after TKA ranges from 0.3% to 2.5% but increases up to 38% in revision TKA cases with supracondylar fractures6.
  2. The risk of fracture after primary TKA is 0.6% 7 versus 1.7% after revision TKA8. Patients aged 70 years or older are 1.6 times more likely to experience a fracture than younger patients, and women are 2.3 times more likely to suffer a fracture than men8.
  3. Periprosthetic fractures of the tibia occur at an incidence of approximately 0.4–1.7% in primary TKA and approximately 0.9% in revision TKA7.
  4. Periprosthetic fractures of the patella occur with an incidence of 0.2–21% of cases, depending on whether patellar resurfacing was performed7.
  5. The incidence of intraoperative periprosthetic fracture is likely underestimated, as some fractures may go undetected, and others with minimal displacement may not require further intervention9.

Several risk factors can contribute to periprosthetic fractures around TKA, including:

  1. Advanced age
  2. Chronic steroid use
  3. Inflammatory arthropathy (e.g., rheumatoid arthritis)
  4. Neurological diseases (e.g., epilepsy, Parkinson's disease) 7
  5. Diabetes mellitus, which can affect post-surgical healing and increase the risk of falls 6

Anterior femoral notching during TKA has been implicated as a potential cause of supracondylar fracture7. Notches greater than 3 mm deep, sharper notches, and notches close to the femoral prosthesis can influence local stress concentration, potentially reducing torsional bone strength by 30–40% and flexural strength by 18%8. Periprosthetic fractures also occur significantly closer to the prosthesis in patients with anterior notching, which can pose challenges for fracture fixation4.

The age group most affected by aseptic periprosthetic fractures around TKA is between 65 and 75 years old6. Factors associated with an increased risk of femoral supracondylar periprosthetic fractures include female sex, dementia, motor alteration, Parkinson's disease, and previous femoral overcut6.

Management of Periprosthetic Fractures

The management of periprosthetic fractures depends on various factors, including the type and location of the fracture, the quality of the remaining bone, the stability of the implant, and the patient's overall medical health10. Delaying surgery for these fractures does not increase mortality or complications but can increase the length of hospital stay1.

Total Hip Replacements

Most cases of periprosthetic hip fractures require surgery10. Postoperative periprosthetic femoral fracture (POPFF) after total hip replacement (THR) is a significant complication and the most common reason for major reoperation following THR. Patients with POPFF also have a high risk of death5. The general approaches to treating these fractures include:

  1. Open reduction and internal fixation (ORIF)
  2. Revision of the total hip replacement with an exchange of some or all of the implants
  3. A combination of both 10

Managing periprosthetic hip fractures can be challenging due to factors such as multiple bone fragments, poor bone quality, and the presence of bone cement11. Revision surgery for periprosthetic femur fractures is associated with a high rate of complications, including malunion, nonunion, implant failure, and infection12.

Postoperative care and recovery after periprosthetic hip fracture surgery typically involve:

  1. Pain management
  2. Rehabilitation, often including physical therapy
  3. Restricted weight-bearing for a specified period
  4. Activity limitations to avoid strenuous activities and heavy lifting
  5. Regular follow-up appointments to monitor progress 11

Total Knee Replacements

Identifying the cause of the fracture is crucial in determining the appropriate therapy for periprosthetic knee fractures13. Conservative treatment, such as casting or bracing, may be an option for undisplaced fractures with a stable prosthesis14. However, conservative treatment often requires a prolonged period of immobility, which can pose risks to the patient, such as deep vein thrombosis, pulmonary embolism, and other complications associated with prolonged bed rest14.

Classification of Periprosthetic Fractures

Several classification systems are used to categorize periprosthetic fractures, which can help guide treatment planning and provide prognostic information.

Total Hip Replacements

The Vancouver classification system is the most widely used system for periprosthetic hip fractures15. This system considers the fracture location, prosthesis stability, and bone quality to guide treatment decisions12. It is important to verify the stability of the femoral component intraoperatively to ensure the correct treatment approach is taken12.

Type Description
Type A Fractures of the greater (AG) or lesser (AL) trochanters
Type B Fractures involving the femoral diaphysis and/or metaphysis around the femoral stem. These are subdivided into:
- B1: Stable stem
- B2: Loose stem but good bone stock
- B3: Loose stem and poor bone stock
Type C Fractures well distal to the tip of the femoral stem

The Unified Classification System (UCS) has been proposed as a standardized system for classifying periprosthetic fractures around various joints, including the hip and knee16. It offers a consistent framework for describing these fractures and guiding their management. The UCS classifies fractures based on their location relative to the implant and includes the following types:

Type Description
Type A Fracture of an apophysis or bone protuberance (e.g., greater trochanter)
Type B Fracture in the bed of the implant or adjacent to it
- B1: Well-fixed implant
- B2: Loose implant
- B3: Loose implant with poor bone quality
Type C Fracture distant from the implant
Type D Interprosthetic fracture between two implants
Type E Fracture involving both bones supporting the implant
Type F Fracture of a bone articulating with a hemiarthroplasty

Total Knee Replacements

Several classification systems are used for periprosthetic fractures around total knee replacements, including the Neer, DiGioia and Rubash, Chen, Lewis and Rorabeck, and Su classifications17. These systems typically consider factors such as fracture displacement, implant stability, and bone quality.

Patella

Periprosthetic patellar fractures are classified based on component stability, bone stock quality, and the integrity of the extensor mechanism14. The Goldberg and Ortiguera and Berry classifications are commonly used for these fractures17.

Surgical Techniques for Fracture Fixation

Surgical intervention for periprosthetic fractures aims to achieve early mobilization, restore axial alignment, and stabilize the limb to allow for joint motion and prevent stiffness18.

Total Hip Replacements

Surgical techniques for periprosthetic hip fractures often involve a combination of revision arthroplasty and trauma techniques to address loose prostheses, bone loss, and the fracture itself19. It is crucial to assess the stability of the femoral component intraoperatively to guide the treatment rationale20.

Common surgical techniques include:

  1. ORIF with cables, plates, and screws 10
  2. Revision of the femoral component to a longer stem prosthesis 3
  3. Use of cortical strut allografts for added stability 3

Minimally invasive surgical techniques are increasingly used for periprosthetic femur fractures, as they can shorten operative time, reduce bleeding, and minimize fracture exposure20.

Total Knee Replacements

Surgical techniques for periprosthetic knee fractures include:

  1. ORIF with plates and screws 22
  2. Intramedullary nailing 22
  3. Revision total knee replacement with larger implants and stems for stability 22
  4. Distal femoral replacement in cases with insufficient bone at the end of the femur 22

The cause of the fracture and the fixation of the components must be considered when managing periprosthetic fractures around TKA13.

Implant Options for Fracture Fixation

Total Hip Replacements

Implant options for periprosthetic hip fractures include:

  1. Screws and plates for ORIF
  2. Cables and wires for cerclage fixation
  3. Longer stems for revision surgery
  4. Allograft bone to supplement weak or missing bone 10

It can be challenging to determine implant loosening with plain radiographs, and computed tomography (CT) scans may be necessary to identify debonding, cement mantle disruption, and osteolysis23.

Comparison of Surgical Techniques and Implant Options

The choice between ORIF and revision arthroplasty for periprosthetic fractures depends on several factors, including fracture location, implant stability, and bone quality10. ORIF is generally preferred for fractures around a well-fixed stem, while revision arthroplasty is often necessary for fractures around a loose stem or with poor bone stock20.

Studies comparing ORIF with revision surgery for periprosthetic femoral fractures have shown that revision surgery can have higher reoperation rates, longer surgical waiting times, and higher transfusion requirements24. However, ORIF of Vancouver type-B3 periprosthetic femoral fractures has been associated with higher revision and reoperation rates than revision arthroplasty25.

Different implant options are available for fracture fixation, including plates, screws, cables, and allografts3. Locking plates offer advantages in terms of stability, especially in osteoporotic bone, but may be associated with a higher rate of nonunion26. Cerclage wires used with locking plate fixation have been shown to be effective in treating periprosthetic fractures of the femur, with faster time to union and fewer revisions27.

Outcomes of Surgical Treatment

The outcomes of surgical treatment for periprosthetic fractures can vary depending on the chosen technique and implant28. Fracture union rates are generally high, but complications such as infection, nonunion, and implant failure can occur26. Periprosthetic fractures are associated with a high morbidity and mortality, emphasizing the need for comprehensive management14.

Factors that can influence outcomes include:

  1. Patient age and comorbidities
  2. Bone quality
  3. Fracture type and location
  4. Implant stability
  5. Surgical technique 10

Recent Advances in Periprosthetic Fracture Management

Recent advances in periprosthetic fracture management include:

  1. Development of specialized periprosthetic screws and variable angle screws and locking plates 21
  2. Increased use of minimally invasive techniques 26
  3. Improved understanding of implant options and their biomechanical properties 29

These advancements have led to more flexible and stable fixation options, reduced surgical morbidity, and improved patient outcomes.

Conclusion

Periprosthetic fractures are a significant concern in orthopedic surgery, with an increasing incidence due to the aging population and the growing number of joint replacement procedures performed. These fractures can be challenging to manage due to factors such as poor bone quality, implant loosening, and the complexity of the surgical procedures involved.

This article has provided a comprehensive overview of periprosthetic fractures around total hip and knee replacements, including their incidence, classification, management, surgical techniques, and implant options. Several key takeaways from this review include:

  1. Early diagnosis and appropriate treatment are essential to minimize complications and optimize patient outcomes.
  2. The Vancouver classification system is a valuable tool for guiding treatment decisions for periprosthetic hip fractures.
  3. A variety of surgical techniques and implant options are available, and the choice depends on individual patient factors and fracture characteristics.
  4. Recent advances in surgical techniques, implant design, and minimally invasive approaches have improved the management of these complex injuries.

Ongoing research is crucial to further enhance our understanding of periprosthetic fractures, improve treatment strategies, and develop innovative solutions to address this growing challenge in orthopedics.

Works cited

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