Fracture after Knee Replacement

So, you’ve undergone knee replacement surgery, hoping to bid farewell to the pain and limitations caused by your worn-out knee joint. However, sometimes unexpected complications arise, one of which is a fracture around the artificial joint. This guide aims to demystify this complication in plain language, helping you understand what it is, why it happens, how it’s diagnosed, and what treatment options are available.

What is a Fracture After Knee Replacement Surgery?

Imagine your knee joint as a puzzle made up of bones, ligaments, and cartilage. Knee replacement surgery involves replacing damaged parts of this puzzle with artificial components. However, just like with any puzzle, sometimes a piece might break or crack. In the context of knee replacement, this break or crack is what we call a periprosthetic fracture.

Why Does it Happen?

Periprosthetic fractures can happen due to various reasons, but the most common cause is the weakening of the bones around the artificial joint. Over time, the bones might become fragile due to factors like osteoporosis (a condition where bones become weak and brittle) or stress placed on the joint after surgery. Sometimes, the fracture can occur during or after surgery due to accidental trauma or improper placement of the artificial components.

Fractures after knee replacement surgery are a rare complication that may require revision knee replacement. Periprosthetic knee fracture may occur as a result of a fall/trauma after the surgery or may occur without any history of trauma/fall as a result of a loose component or mal-aligned component.

Fractures around the prosthetic knee joint that are not displaced may be treated with nonsurgical treatment options, however, displaced fractures usually require surgical treatment.

A knee replacement surgery is done after all nonsurgical methods of treatment have been tried for knee arthritis. The surgery involves cutting the diseased ends of the bones forming the knee joint. The lower part of the thigh bone (femur) is cut and replaced with a femoral component. Similarly, the upper part of the shin bone (tibia) is cut and replaced with a tibial component. The undersurface of the kneecap is usually resurfaced and a plastic component is fixed to it.

The periprosthetic fracture after knee replacement may occur during the surgery, immediately after the surgery, or days/weeks/years after the surgery. The fracture may occur in the femur, the tibia, or the patella. There may be certain risk factors associated with periprosthetic knee fracture such as:

• Inflammatory arthritis such as rheumatoid arthritis increases the chances of fracture after knee replacement.
• Elderly patients who may have a metabolic bone disorder such as osteoporosis are at an increased risk for periprosthetic fractures.
• Long-term steroid use may weaken the bones and to periprosthetic fractures after knee replacement.
• Certain neurological diseases such as Parkinson’s disease, epilepsy, polio, etc. may increase the risk for fracture.
• Localized factors such as stiffness of the knee, aseptic osteolysis, infection increase the chance of periprosthetic fracture.

Femoral periprosthetic fractures

The fracture inner side of the lower end of the femur (medial femoral condyle) occurs mostly during the surgery. The management of femur periprosthetic fractures depends upon the location of the fracture and the stability of the prosthesis.

Non displaced stable periprosthetic fractures may be managed with nonoperative methods use as braces or casting. Fractures above the prosthesis with a stable prosthesis may be fixed with a nail or a metal plate which is fixed with screws.

A loose femoral component is managed with a revision involving a femoral component with a long stem. Rarely, an extensive fracture in the elderly may require the replacement of the entire lower end of the femur (distal femoral replacement).

Tibial periprosthetic fractures

Tibial fractures occur most commonly due to mal-aligned components or in patients with a prior history of tibial surgery. Nonsurgical treatment in the form of bracing/casting may be done for nondisplaced stable fracture. Unstable fractures with a stable prosthesis may be managed with plates, cables, wires, etc. Fractures with an unstable prosthesis are revised usually with a long stem prosthesis.

Patellar periprosthetic fractures

Kneecap (patella) fractures are common in cases where the patella is resurfaced with a plastic prosthetic component. Fractures of the patella occur commonly due to intraoperative surgical techniques. Damage to the blood supply of the patella may lead to patellar bone death and subsequent fracture.

Irregular resurfacing of the patella, inappropriate thickness of the residual patella, and the use of single peg implants have been associated with patellar periprosthetic fractures.

Patellar fractures leading to disruption of the extensor mechanism (the ability to raise a straight leg), or with an unstable prosthesis are managed with surgical treatment. The surgical treatment may consist of removal of the patella, wire fixation, partial removal of the patella, revision of prosthesis, etc.

Stable fractures may be fixed with nonsurgical methods such as casting/bracing. Patients with periprosthetic patella fractures may complain of only minor pain in front of the knee as compared to tibial or femoral periprosthetic fractures where the pain is severe prompting a visit to the ER.

 

Treatment Options

The treatment for a fracture after knee replacement depends on several factors, including the type and severity of the fracture, your overall health, and your lifestyle. Here are some common treatment options:

Non-Surgical Treatment: In less severe cases, where the fracture is stable and the bones are in good condition, non-surgical approaches like immobilization with a brace or cast may be sufficient. Physical therapy might also be recommended to help strengthen the muscles around the knee and improve mobility.

Surgical Repair: If the fracture is severe or unstable, surgery may be necessary to realign the bones and secure them with implants like screws, plates, or rods. In some cases, your surgeon may need to replace or revise the existing knee implant to ensure stability and proper healing.

Revision Surgery: In situations where the fracture occurs due to issues with the initial knee replacement surgery, such as implant loosening or misalignment, a revision surgery may be required to correct these problems and prevent future complications.

 

Recovery and Rehabilitation:

Recovering from a fracture after knee replacement surgery can be challenging, requiring patience, dedication, and support from healthcare professionals and loved ones. Your recovery timeline will depend on factors like the type of treatment received, your overall health, and how well you follow your doctor’s instructions. Physical therapy plays a crucial role in rehabilitation, helping you regain strength, flexibility, and function in your knee joint. It’s essential to follow your therapist’s exercises diligently and avoid activities that could strain or reinjure your knee during the healing process.

 

Prevention

While not all periprosthetic fractures can be prevented, there are steps you can take to minimize your risk:

Maintain a healthy lifestyle: Eating a balanced diet rich in calcium and vitamin D, staying physically active, and avoiding smoking can help keep your bones strong and reduce the risk of osteoporosis.

Follow post-operative instructions: After knee replacement surgery, follow your doctor’s recommendations for rehabilitation exercises, activity restrictions, and follow-up appointments to ensure proper healing and early detection of any potential issues.

Be cautious: Take precautions to prevent falls and accidents, especially during the early stages of recovery when your knee may be more vulnerable to injury. Use assistive devices like canes or walkers if needed, and make necessary modifications to your home environment to reduce the risk of slips and falls.

 

Conclusion

While a fracture after knee replacement surgery can be a daunting complication, understanding its causes, symptoms, and treatment options can empower you to make informed decisions about your care. By working closely with your healthcare team and following their guidance, you can navigate the challenges of recovery and eventually regain mobility and independence in your daily activities. Remember, you’re not alone in this journey, and with patience and perseverance, you can overcome this setback and get back to enjoying life to the fullest.