Forward: Meniscal-bearing Knee: Innovating Unicompartmental Knee Arthroplasty

In November 2006, surgeons from around the world gathered in Oxford, England to celebrate the 30th anniversary of the Oxford Knee (Biomet Orthopedics, Inc, Warsaw, Ind). This supplement to Orthopedics is intended to further highlight the outstanding contribution that the Oxford Knee has made to the treatment of the arthritic knee.

The popularity of unicompartmental arthroplasty has fluctuated over the past three decades. Most recently, with the advent of minimally invasive techniques and improved outcomes, the procedure is gaining more and more momentum. The United States Food and Drug Administration approval of the Oxford knee in April 2004 is another reason why unicompartmental knee arthroplasty is becoming a highly accepted treatment for medial compartmental disease. In 1976 the first Oxford Knee was implanted, and after 30 years of clinical use, the design has remained relatively unchanged.

The Oxford device is a fully congruent implant at both interfaces throughout the range of motion. This full congruency has been shown to minimize complications associated with unicompartmental knee replacement.¹ The unique meniscal bearing is also fully unconstrained, which allows unrestricted movement.

Since the late 1980s, the Oxford Knee has been used exclusively as a unicompartmental device for a condition known as anterior medial osteoarthritis. While the Oxford implant geometry, bearing design, and biomechanical philosophy have remained relatively constant, evolution in the instrumentation, sizing, and implantation technique have occurred. The original Phase I design required free-hand bony resections without an accurate means of balancing. The Phase II brought about more accurate instrumentation, including the mill and spigot system for flexion and extension gap balancing. The introduction of Phase III involved multiple femoral sizes and instrumentation specifically designed for minimally invasive procedures. The Phase III design is used throughout the world today and is the implant of discussion in this piece.

This supplement chronicles the early experience of the Oxford unicompartmental knee arthroplasty device in the United States. The reader will find a multitude of manuscripts from authors from around the world highlighting this 30-year experience. The supplement also includes topics relevant to the indications, implantation, and results of unicompartmental knee arthroplasty using the Oxford unicompartmental knee arthroplasty device among others.

The original Oxford group consisting of its inventors and greatest supporters has written on the extensive history of Oxford unicompartmental knee arthroplasty among other topics. The results of prospective and retrospective long-term studies and an investigation into special indications for the Oxford knee such as combined ACL reconstruction and unicompartmental knee arthroplasty are also discussed. Furthermore, we are honored to have contributions from the foremost authority on polyethylene contact stresses, Seth Greenwald, DPhil(Oxon) and colleagues.

In addition, the supplement highlights an evaluation of the importance of limb alignment, and an investigation into the radiolucency and migration of the components following implantation are contained herein. No surgery is without its potential complications, and one such issue, medial tibial plateau fracture, is discussed. The instrumentation and implantation technique for the Oxford unicompartmental knee arthroplasty make this a rare occurrence.

Lastly, with much debate over the use and amount of anticoagulation therapy necessary to treat our orthopedic patients, this supplement offers an analysis of a large cohort of unicompartmental knee arthroplasty patients that evaluates the risk of deep vein thrombosis and pulmonary embolism in these patients.

It is with great honor that Biomet Orthopedics, Inc, along with Drs Goodfellow, O’Connor, Dodd, and Murray from Oxford University, bring to you this anniversary supplement as a tribute to 30 years of mobile-bearing knee technology. I would like to also thank SLACK Incorporated and acknowledge Dr Robert D. D’Ambrosia, Chief Medical Editor, for their unwavering support and dedication to this supplement.

Reference

Murray DW, Goodfellow JW, O’Connor JJ. The Oxford medial unicompartmental arthroplasty, a ten year survival study. J Bone Joint Surg Br. 1998; 80:983-989.