Copyright © 2009 by The Journal of Bone and Joint Surgery, Inc.
Commentary & Perspective
Commentary & Perspective by
Stuart B. Goodman, MD, PhD*,
Stanford University Medical Center, Stanford, California
Posted January 2009
Total knee arthroplasty is a very successful reconstructive
procedure that decreases pain and improves function and quality of life for
patients with end-stage arthritis. The fifteen-year rate of survivorship after
knee arthroplasty has been reported to be >90% for commonly used knee
prostheses implanted by experienced surgeons1-3. Despite this
success, two points regarding the outcomes of knee arthroplasty should be
considered. First, in the United States, the majority of joint replacements are
performed by surgeons who do fewer than fifteen of these procedures per year. Second,
kinematic function and wear of implant surfaces are optimized if the knee
arthroplasty is positioned within 3° of the mechanical axis. Thus, surgeons are
beginning to examine new technological methods, such as computer-assisted
navigation, to more consistently achieve optimal implant alignment and
orientation4. These new technologies must be safe, accurate,
reproducible, simple to use, and cost-effective.
Kim and colleagues at The Joint Replacement Center of Korea
in Seoul, South Korea are highly experienced joint-replacement surgeons. They
report the outcome of a prospective series of 160 patients who underwent
bilateral knee arthroplasty by one surgeon. Each patient underwent one total knee arthroplasty with use of
computer-assisted surgical navigation and the contralateral total knee
arthroplasty with use of conventional techniques and instrumentation. All
components were the NexGen cruciate-retaining high-flex cemented total
knee prosthesis (Zimmer, Warsaw, Indiana). The computer-assisted surgical
navigation system that was used was the VectorVision CT-free knee (BrainLAB,
Munich, Germany). A power analysis helped to ensure that a sufficient number of
patients were included in the study.
There were no
differences between the two groups with respect to knee score, range of motion,
implant position, or the prevalence of outliers of implant position at 3.4
years postoperatively. Assuming a tolerance level of 3°, the range of outliers
was slightly greater (but did not reach statistical significance) for
conventional arthroplasty as compared with computer-assisted knee arthroplasty
for all parameters examined. On the average, computer-assisted knee
arthroplasty required eighteen more minutes of surgical time and twenty-six
more minutes of tourniquet time (p < 0.001).
The strengths of this study include the prospective design,
the performance of bilateral knee arthroplasties by a single experienced
surgeon, blinded follow-up with use of defined clinical and radiographic
parameters, and use of the same knee prosthesis and navigation system in all
patients. Limitations include lack of inclusion of knees with the more
challenging valgus deformity and a short average follow-up of 3.4 years. Perhaps
a larger series with a longer follow-up would demonstrate increased wear and
subsequent need for revision in knees that are operated on with use of the conventional
surgical technique. General limitations of computer-assisted navigation include
difficulties in identifying crucial landmarks for registration, lack of
agreement concerning the identification of the tibial axis, and the extra time
and costs involved5-7. Whether computer-assisted navigation would prove
to be more useful for surgeons who are less experienced is also an important
and relevant unknown factor. At present, the use of computer-assisted navigation
remains controversial and may not offer major advantages to surgeons who are
experienced in performing total knee arthroplasty.
*The author did not receive any outside funding or grants in support of his research for or preparation of this work. Neither he nor a member of his immediate family received payments or other benefits or a commitment or agreement to provide such benefits from a commercial entity.
References
1. Rodricks DJ, Patil S, Pulido P, Colwell CW Jr. Press-fit condylar design total knee arthroplasty. Fourteen to seventeen-year follow-up. J Bone Joint Surg Am. 2007;89:89-95.
2. Vessely MB, Whaley AL, Harmsen WS, Schleck CD, Berry DJ. Long-term survivorship and failure modes of 1000 cemented condylar total knee arthroplasties. Clin Orthop Relat Res. 2006;452:28-34.
3. Ma HM, Lu YC, Ho FY, Huang CH. Long-term results of total condylar knee arthroplasty. J Arthroplasty. 2005;20:580-4.
4. Ensini A, Catani F, Leardini A, Romagnoli M, Giannini S. Alignments and clinical results in conventional and navigated total knee arthroplasty. Clin Orthop Relat Res. 2007;457:156-62.
5. Yau WP, Leung A, Liu KG, Yan CH, Wong LL, Chiu KY. Interobserver and intra-observer errors in obtaining visually selected anatomical landmarks during registration process in non-image-based navigation-assisted total knee arthroplasty. J Arthroplasty. 2007;22:1150-61.
6. Siston RA, Patel JJ, Goodman SB, Delp SL, Giori NJ. The variability of femoral rotational alignment in total knee arthroplasty. J Bone Joint Surg Am. 2005;87:2276-80.
7. Siston RA, Goodman SB, Patel JJ, Delp SL, Giori NJ. The high variability of tibial rotational alignment in total knee arthroplasty. Clin Orthop Relat Res. 2006;452:65-9.
|
