As we enter our sixth decade of total hip replacement and our fifth decade of total knee replacement, the orthopedic community can take pride in the substantial improvements that have been made in these operations which produce validated improvements in patients’ lives. The incidence of two of the most feared complications of joint replacement infection and thromboembolic disease, has been substantially reduced. In addition, the incidence of instability in total hip replacement has decreased significantly, and the length of hospital stays has decreased remarkably for hip and knee replacement. Despite these improvements, there is a real interest by patients for “less invasive, faster recovery” surgery modifications.
If one looks at the development of urologic, bariatric and colorectal surgery, all have reduced the use of open surgical procedures in favor of less invasive — and in many cases, more accurate — scope-assisted procedures. In our own field, cruciate ligament and rotator cuff surgery are areas in which arthroscopic surgical techniques have largely eliminated open surgery. It is likely that we will see further development of arthroscopically assisted hip and knee arthroplasty.
There will be continued improvement in the treatment of pre-arthritic conditions such as osteochondritis dessicans and traumatic chondral defects. This will likely start with partial prosthetic resurfacing as a bridge to more biologic implants such as cell-seeded scaffolds. Moldable implant materials, implants which can be assembled inside the joint (like a ship in a bottle), as well as surgical concepts such as “smart” burrs and soft tissue-guided surgery will contribute to arthroscopic or very small incision surgery for knee defect reconstruction.
Emerging data from sources such as the National Institutes of Health-sponsored Osteoarthritis Initiative indicate that a large percentage of patients with symptomatic knee arthritis have changes predominantly in one tibiofemoral compartment. This suggests an opportunity to address knee arthritis with unicompartmental resurfacing techniques, both synthetic and biologic.
Just as in knee arthritis, chondral loss in hip osteoarthritis is not uniform, with certain parts of the femoral and acetabular articular surface remaining largely intact until the later stages of the disease. This opens up the possibility of
partial hip replacement once the pathologic malalignment is addressed
Once malalignment is corrected, partial resurfacing of areas of chondral loss may become more successful. In fact, there are already products developed that allow partial resurfacing of the femoral head in cases of osteonecrosis with collapse or traumatic defects. These would include metal, polymeric, allograft or tissue-engineered dowel grafts, as well as engineered or prosthetic bipolar “inlay grafts” in which preparation of the acetabular recipient bed also allows access to the damaged portion of the femoral head without hip dislocation.
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