Future of replacement may include more resurfacing, percutaneous fixation

Anthony M. DiGioia, Editor

William A. Jiranek

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 history is our guide, the evolution of surgical techniques has been consistent among all surgical disciplines in the following ways:

• modifications of indications and techniques for a procedure due to better understanding of the pathophysiology of the disease;
• the progression of less invasive techniques; and
• successful techniques, which are cost-effective.

Increasing recognition of the importance of malalignment in the development of osteoarthritis of the hip and knee will continue to drive the development of techniques which address malalignment. The expanding knowledge of femoroacetabular impingement will spur earlier intervention strategies to delay or eliminate the need for total hip replacement. The same will apply for varus gonarthrosis. This will likely involve correction of alignment and partial resurfacing strategies.

Surgical techniques

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.

It is clear that future surgical innovation will have to demonstrate cost reductions as well as improvement in care. Most of the cost savings will likely be indirect: reduced length of stay, decreased ancillary procedures and decreased complications.

Treatment of knee disorders

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.

Improvements in surgical navigation systems will allow surgeons to more precisely control tibiofemoral alignment during osteotomy, and less invasive osteotomy techniques will inevitably follow. This will likely include navigated cutting tools inserted in a small incision as well as percutaneous fixation strategies.

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.

The predominant argument against partial knee arthroplasty is the higher early failure rate within the first 5 years, which has been demonstrated in most national registries. While in some registries this difference in failure rates is double for partial knee replacement, the failures comprise less than 5% of all partial arthroplasties performed. This must be contrasted against ample evidence of improved kinematics, decreased hospital and rehabilitation time, lowered infection rate and improved patient satisfaction of partial knee replacement compared with total knee replacement.

Management of hip disorders

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.

In the arena of femoroacetabular impingement, current “bumpectomy” strategies, such as osteochondroplasty and rim resection, may decrease symptoms, but may not change the natural history of the disease. As with the knee, as navigation techniques improve and our understanding of what normal alignment should be increases, it may be possible to reposition acetabulae and femora to within a certain “safe” window. As with the knee, this should be facilitated by arthroscopic assistance and navigated cutting tools. Percutaneous or limited open fixation strategies will also likely be developed.

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.

More precise targeting of lesions in the femoral head and acetabulum will allow surgeons to remove diseased portions of the head through a transosseus approach, replacing them with prostheses or moldable polymers.

Current projections for increased demand for hip and knee arthroplasty are based on an increase of Americans at risk (for example older than a certain age) for replacement. Whether early intervention will affect the number of patients who develop end-stage arthritis and require total arthroplasty is still not clear, but there are likely savings to the health care system if the increasing incidence of total joint arthroplasty can be slowed.

Reference:

• Riddle DR et al. Extent of tibiofemoral osteoarthritis prior to knee arthroplasty: Multicenter data from the osteoarthritis initiative. J Bone Joint Surg Am, In review.

• Anthony M. DiGioia, III, MD, is the editor of Emerging Technology & Innovation. He can be reached at Renaissance Orthopaedics, PC, and Pittsburgh, Pennsylvania Innovation Center, Magee-Women’s Hospital of UPMC, Pittsburgh; email: tony@pfcusa.org.
• William A. Jiranek, MD, is the chief, Adult Reconstruction Section, in the Department of Orthopaedic Surgery, Virginia Commonwealth University Health System, 9000 Stony Point Parkway, Richmond, VA, 23139; 804-228-4162; email: wjiranek@gmail.com.
• Disclosures: DiGioia is a shareholder in Blue Belt Technologies. Jiranek is a consultant and receives royalties from DePuy, and is an American Association of Hip and Knee Surgeons board member.