Introduction
Periprosthetic fractures occur following total knee arthroplasty and may occur in any part of the tibia, femur, or patellar bone. The femur bone is more susceptible to periprosthetic fractures than the tibia and patella. It is mainly seen in the supracondylar area of the distal femur bone. The incidence of periprosthetic fractures is increasing worldwide due to increased joint arthroplasties, revision surgery, and improvements in the healthcare sector.
What Is Total Knee Arthroplasty (TKA)?
Worn-out or damaged surfaces of the knee joint are removed surgically and replaced with artificial structures called implants; this procedure is called knee arthroplasty or knee replacement surgery. It is usually indicated in the treatment of osteoarthritis, rheumatoid arthritis, or in cases of severe trauma to the knee joint.
What Are Periprosthetic Fractures?
Any break or fracture in the bone around the implants or internal fixation device is called a periprosthetic fracture. Periprosthetic fractures may occur following the knee, shoulder, or hip total replacement surgery and are mainly seen in women than men, occurring approximately two to four years after the surgery. Periprosthetic fractures following a total hip arthroplasty are more common compared to total knee or shoulder arthroplasty.
What Are the Causes of TKA Periprosthetic Fractures?
Some of the causes of periprosthetic fractures are
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Low-energy trauma or a fall.
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Mechanical stresses which are caused by the implant.
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A mismatch between the bone density and implant.
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Poor bone quality or bone loss.
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Poor vision or imbalance.
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Revision surgery.
What Are the Risk Factors for TKA Periprosthetic Fractures?
Some of the risk factors of periprosthetic fractures are
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Prolonged use of steroids.
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Low mineral content of bone (osteopenia) and weak and brittle bones (osteoporosis).
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Osteolysis (destruction of periprosthetic bone) and delayed bone remodeling.
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Rheumatoid arthritis, knee joint ankylosis.
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Advanced age.
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Neurological disorders like Parkinson’s disease, cerebral palsy, polio, epilepsy, and myasthenia gravis, cerebral ataxia.
What Are the Signs and Symptoms of TKA Periprosthetic Fractures?
Signs and symptoms of periprosthetic fractures include:
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Pain and swelling around the prosthesis area.
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Inability to bear weight.
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Deformed leg.
What Are the Types of Periprosthetic Fractures of the Knee?
Periprosthetic fractures of the knee can involve the femur, usually in the area of supracondylar (supracondylar fracture of the femur), fracture of the tibia (shin bone), and fracture of the patella (kneecap).
1. Supracondylar Fracture of the Femur: It is the most common periprosthetic fracture of the knee, occurring two to four years after the surgery, following a low-energy trauma, like a slip or a fall; it may be seen in high-energy trauma also. Periprosthetic fractures of the femur were classified by Rorabeck and Taylor, based on implant fixation and displacement of the fracture, as :
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Type I: Nondisplaced fracture around a well-fixed prosthesis.
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Type II: Fractures having displacement more than 5 mm or more than 5-degree angulation, stable prosthesis. Type IIA is associated with non-comminuted fractures, and Type II B is associated with comminuted fractures. A type of fracture wherein the bone is broken into two or more parts is called a comminuted fracture.
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Type III: Fractures having a displacement, with the prosthesis being loosened or unstable.
2. Periprosthetic Fracture of the Tibia: It is comparatively lower than the periprosthetic fracture of the femur. It is usually caused due to acute trauma or can happen at any stage of the knee arthroplasty surgery, like implant insertion, implant placement, or removal of the previous prosthesis during revision surgery. It is usually associated with implant loosening, malalignment, malposition, and joint instability. Periprosthetic fractures of the tibia can be classified based on Felix as follows:
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Type I: Fractures located at the tibial plateau.
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Type II: Fractures located inferior to the tibial plateau, adjacent to the prosthetic stem.
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Type III: Fractures located distal to the tibial stem.
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Type IV: Fractures involving the tibial tubercle.
Felix has also classified these fractures into three subtypes;
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Type A: Fractures with stable prosthesis on radiographs.
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Type B: Fractures with loosened prosthesis on radiographs.
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Type C: Intraoperative fractures.
3. Periprosthetic Fractures of the Patella: It is the most uncommon periprosthetic fracture of the knee and is mainly seen in males, occurring due to direct trauma or fatigue. Patellar periprosthetic fractures were classified into four types by Goldberg:
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Type I: Fractures located at the periphery of the patella, which do not involve a patellar component and extensor mechanism.
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Type II: Fractures that disrupt the implant-bone composite or extensor mechanism.
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Type III: Fractures involving the inferior pole of the patella; type IIIA with patellar ligament rupture and type IIIB without patellar ligament rupture.
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Type IV: Fractures associated with a patellofemoral dislocation.
How Are Periprosthetic Fractures Diagnosed?
A complete medical history is taken, during which the patient may have a history of minor trauma and inability to bear weight. Physical examination is performed, and soft tissue injuries and lacerations are noted along with previous skin incisions. In some cases, there may be the absence of an apparent swelling or deformity. Diagnosis of periprosthetic fractures involves determining whether the implant is loose, identifying the presence or absence of displacement and whether the reduction is required or not, and determining the appropriate treatment for the displaced fracture. Radiological investigations are advised, which include
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Anterior-posterior views and lateral and oblique views. A lateral view is preferable as it helps assess the fracture displacement and shows the bone availability for device fixation. In the case of supracondylar fractures of the femur, long-leg radiography is advised for confirmation.
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In some cases, a computed tomography (CT Scan) may also be recommended.
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In cases of only pain, without evidence of fracture, joint aspiration and blood tests are done to rule out infections.
How Are TKA Periprosthetic Fractures Managed?
Management of TKA periprosthetic fractures is a challenging task for an orthopedic surgeon. The major treatment goal would be to restore the pre-fracture functional status of the patient, which includes preservation of the implant components without loosening, fracture union, proper prosthesis alignment, and restoring the range of motion. The success of the treatment mainly depends on the displacement of the fracture, the degree of osteopenia, and the status of the prosthetic components. Periprosthetic fractures are managed by nonoperative and operative methods.
1. Nonoperative Treatment: Conservative management is performed for nondisplaced fractures and is preferred since it is non-invasive and has no risk of bleeding, infections, or other post-surgical complications. Disadvantages include malunion, loss of function, and limitations in case of patients with osteopenia. It includes skeletal traction, splinting, casting, and cast bracing. In case of reduction requirement, closed reduction is made, followed by immobilization for four to six weeks, during which the fracture alignment and implant stability are monitored biweekly. If implant instability or displacement is suspected, nonoperative treatment is replaced by operative management.
2. Operative Management: It mainly depends on the location of the fracture, bone quality, size of the distal fragment, and condition of the implants. It is employed in displaced or unstable fracture cases; rigid fixation is necessary, which helps in better results and an early range of motion.
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Joint Revision Surgery: It is required in cases of unstable fractures, irrespective of displacement, comminuted fractures, failure of other treatments, or in cases of severe malalignment of the prosthesis. During this surgery, a long-stemmed femoral component is inserted through the fracture site, along with structural distal femoral allograft, which helps establish implant and fracture stability.
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Open Reduction And Internal Fixation: This procedure provides rigid fixation, anatomical reconstruction, and early range of motion. Condylar screws and plates are used in cases of less comminuted fractures, and in cases of comminuted fractures, bone grafting or bone cement augmentation is performed.
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Rigid Supracondylar Interlocking And Fixation: It is a minimally invasive procedure that provides good rotational and angular stability. A minimal patellar splitting approach is followed with the placement of interlocking screws. It usually requires supplemental bone grafting, and it cannot be used in cases of severely comminuted fractures.
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Locking Plates: It is used in the case of patients with osteopenia as it is minimally invasive, and a prosthesis can be inserted easily. It is recommended in cases where an implant is overlapping in the proximal part of the femur bone.
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Metal Augmentation and Thick Polyethylene Insertion: It is recommended in cases of tibial periprosthetic fractures with severe bone defects or comminuted fractures.
What Are the Complications of Periprosthetic Surgery?
Some of the complications include
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Malunion or non-union, which can result in the loosening of the prosthesis, and pain.
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Infections at the surgical site hamper the healing process.
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Prosthetic failure or inability of rigid fixation.
What Are the Precautions to Be Taken After Surgery?
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Assessment of bone health regularly, following a healthy lifestyle.
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Regular use of calcium and Vitamin D in cases of patients with osteoporosis.
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Being extra conscious and preventing falls and injuries.
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Regular follow-up after treatment to prevent a recurrence.
Conclusion
Total knee arthroplasty (TKA) periprosthetic fractures are seen above or around an implant and are associated with pain, swelling, and inability to bear weight. It is primarily seen in elderly women with osteoporosis or osteopenia after two to four years of surgery. It usually occurs in any part of the femur, tibia, or patellar bone. Undisplaced or minimally displaced fractures can be managed by nonoperative methods, and displaced and unstable prostheses are treated by open reduction or revision surgery. TKA periprosthetic fractures can be successfully managed when treated appropriately.
