Is Joint Line Elevation Really a Problem? The Data on Revision Knee Outcomes

Exploring the radiographic measurements of joint line height and posterior condylar offset to determine what actually drives clinical success in revision TKA.

Treatment goals in revision total knee arthroplasty (rTKA) are to perform a durable reconstruction that alleviates a patient’s pain and improves function. In rTKA, joint line elevation may occur when bone lost from the distal femur is not replaced, leading to historical recommendations that distal femoral augments be used to restore a native joint line. The consequences of an elevated joint line were postulated to be inferior patient outcomes, decreased range of motion, less extensor strength, and anterior knee pain. Previous studies demonstrate that elevation of the joint line by 5-8 mm is associated with inferior outcomes.

Interestingly, many “symptoms” of an elevated joint line can also be explained by instability, which has recently been described as one of the leading reasons for additional revisions of rTKAs. Therefore, many surgeons recommend balancing the flexion and extension gaps intraoperatively as a primary goal in rTKA. After component removal, a larger flexion space compared to extension space is frequently present, and this asymmetric gap can oftentimes be addressed by proximalizing the femoral component and increasing the polyethylene insert thickness, resulting in an elevated joint line in up to 80% of cases.