What is Acute Knee Replacement for Fractures?
Acute knee replacement for fractures refers to a surgical intervention where a knee replacement (either partial or total) is performed shortly after a traumatic injury to the knee, typically involving fractures of the distal femur, proximal tibia, or patella. This approach is most commonly used in cases where the fractures are complex, comminuted (broken into multiple pieces), or not amenable to standard fixation methods such as plates, screws, or rods.
Knee replacement surgery, also referred to as total knee replacement or total knee arthroplasty, is a surgical procedure in which the worn-out or damaged parts of the knee joint are removed and replaced with artificial knee components called prostheses or implants made of metal, ceramic, or plastic.
Anatomy of the Knee
The knee is made up of the femur (thighbone), tibia (shinbone), and patella (kneecap). The lower end of the femur meets the upper end of the tibia at the knee joint. A small disc of bone called the patella rests on a groove on the front side of the femoral end. Another bone of the lower leg (fibula) forms a joint with the shinbone. To allow smooth and painless motion of the knee joint, the articular surfaces of these bones are covered with a shiny white slippery articular cartilage. Protective tissues, ligaments, tendons, and muscles hold the bones together.
Indications for Acute Knee Replacement for Fractures
Some of the common indications for acute knee replacement for fractures include:
- Severe joint damage with articular cartilage involvement
- Elderly patients with osteoporosis, where the bone quality is poor for fixation
- Pre-existing osteoarthritis in the knee, making joint salvage less viable
- Severely comminuted distal femoral or proximal tibial fractures
- Cases where functional recovery is critical and prolonged immobilization would be detrimental
Procedure for Acute Knee Replacement for Fractures
During an acute knee replacement surgery for fractures, the damaged parts of the knee joint and adjacent bone, typically resulting from a traumatic injury like a comminuted distal femoral fracture, are replaced with prosthetic components. This surgery aims to provide immediate stability, restore function, and allow early mobilization, especially in cases where traditional fixation is not feasible.
In general, the procedure involves the following steps:
- The patient is administered with general or regional anesthesia (spinal or epidural).
- The surgeon makes an incision over the knee, typically along the front (midline).
- Damaged skin, soft tissue, and bone fragments are carefully exposed while protecting surrounding structures like ligaments and blood vessels.
- Fractured and nonviable bone fragments in the distal femur and/or proximal tibia are removed.
- If the fracture extends into the articular surface, it is excised entirely to prepare for prosthetic implantation.
- The remaining femur and tibia are shaped to accommodate the prosthetic components.
- If necessary, bone cement or augmentations are used to fill gaps or reinforce weak areas, particularly in osteoporotic bones.
- A prosthetic distal femur and tibial component are implanted. These components may be:
- Standard prostheses: For simpler cases.
- Constrained or hinged prostheses: For severe instability or extensive bone loss.
- The components are secured using bone cement or press-fit techniques.
- If the patella (kneecap) is damaged or arthritic, it may be resurfaced with a polyethylene component.
- The muscles are then re-approximated (joined neatly), and the incision is closed with sutures or staples and covered with a sterile dressing.
Postoperative Care and Recovery
After an acute knee replacement for fractures, postoperative care focuses on pain management, early mobilization, and prevention of complications. Pain is controlled using a combination of medications, including opioids, nonsteroidal anti-inflammatory drugs (NSAIDs), and regional nerve blocks if needed. Prophylactic antibiotics and anticoagulants may be prescribed to prevent infection and blood clots. Patients are advised to use assistive devices like crutches or walkers initially for mobility. Patients are encouraged to begin gentle range-of-motion exercises and weight-bearing activities, often under the guidance of a physical therapist, within the first few days after surgery to promote healing and prevent stiffness. Wound care includes keeping the incision clean and dry, with sutures or staples removed during follow-up visits. Regular follow-ups with the surgeon are necessary to monitor healing and assess implant alignment through imaging. Adherence to prescribed exercises and activity restrictions is crucial for restoring strength, stability, and function, and helping patients regain independence as quickly as possible.
