The complex posttraumatic knee: surgical techniques and implant selection

The posttraumatic osteoarthritic (PTOA) knee is a challenging condition that should not be underestimated by the treating surgeon. In general, patients with PTOA of the knee have a lower functional level, quality of life, and implant survival rate than those patients with primary osteoarthritis [1]. Thus, the treating surgeon should have a realistic and pragmatic approach when dealing with such cases. In this article, Friedrich Boettner, orthopedic surgeon at the Hospital for Special Surgery, New York, US, uses his years of surgical experience to take the surgeon through techniques and tips on how to perform a total knee arthroplasty (TKA) in a patient with PTOA of the knee.

Things to consider when performing a total knee arthroplasty in a posttraumatic knee

Preoperative planning and evaluation are crucial when performing a TKA in a PTOA knee (as described in Part 1  of this series of articles). Every injury is different, every patient recovers slightly differently from the initial injury, and patient characteristics vary, meaning surgeons will rarely see identical cases. Once the surgical indication for TKA has been established, the surgeon can perform the TKA either in a one-stage or two-stage approach depending on whether there is a need for a corrective osteotomy (Part 2), issues with or infections of preexisting hardware, or complications with bone loss or compromised soft tissue. Ultimately, the surgeon aims to recreate a stable, well-balanced knee with good range of motion (ROM).

Dealing with soft-tissue defects

A knee with multiple previous incisions requires careful incision planning. Usually, surgeons will try to incorporate prior incisions; however, the goal is to make sure the angle between incisions is larger than 45° and the most lateral incision is used preferentially. Older incisions (> 15–20 years) can often be ignored, as they usually no longer impact the blood supply of the skin. Beside evaluating for previous incision sites and their associated scar tissue, the surgeon needs to make sure to identify any subcutaneous flaps. In terms of compromised skin, preexisting muscle flaps, or necrotic skin areas, the incision planning should include consultation with a plastic surgeon, especially if muscle flaps or skin grafts are needed to provide wound coverage.

In addition, any compromise of the popliteal artery and vein at the level of the knee needs to be ruled out. This is especially important in subluxated or dislocated knees. Concerning are sagittal deformities where the femur is dislocated posterior on the tibia. Boettner would strongly recommend identifying these cases preoperatively, and to use an MRI to better visualize the location of the vessels prior to surgery. A vascular surgeon should be available when operating on patients with a higher risk of vascular injury.