Commentary & Perspective

Commentary & Perspective on
"Comparison of Simultaneous Bilateral with Unilateral Total Knee Arthroplasty in Terms of Perioperative Complications"
by Daniel P. Bullock, BA, et al.

Commentary & Perspective by
Charles R. Clark, MD*,
Department of Orthopaedic Surgery, University of Nebraska Medical Center, Omaha, NE

Total knee arthroplasty is a very common procedure in the United States, with more than 300,000 total knee arthroplasties performed annually¹. The authors note that a great number of candidates for total knee arthroplasty have bilateral disease and therefore may require bilateral arthroplasty. They hypothesized that there would be no difference in the prevalence of perioperative complications between unilateral total knee arthroplasty and simultaneous bilateral total knee arthroplasty performed with a standard surgical technique and postoperative protocol.

The authors performed a retrospective review of patients undergoing total knee arthroplasty between January 1994 and June 2000. All patients had radiographic and clinical evidence of bilateral disease and were offered bilateral surgery. The bilateral procedures were performed simultaneously by two surgical teams. The authors performed a power analysis to determine an adequate sample size and determined that they needed 500 patients treated with unilateral arthroplasty and 250 treated with bilateral arthroplasty to achieve 80% power and have a Type-I error of 0.05. They evaluated 514 unilateral and 255 bilateral consecutive, nonselected total knee arthroplasties that met their inclusion criteria.

There was no significant difference between the unilateral and bilateral groups with regard to thirty-day and one-year mortality rates, but there was a significant difference between the groups with regard to myocardial infarction within thirty days. The rate of transfusion was significantly greater in the bilateral group. The average length of stay averaged only 0.69 day longer in the bilateral group than in the unilateral group, resulting in a savings of 3.73 days, if one were to consider two consecutive unilateral procedures.

The authors concluded that the results suggested a relative risk of myocardial infarction of 5.13 in the bilateral cohort compared with the unilateral cohort during the first thirty postoperative days. Their findings of an increased perioperative risk are consistent with the findings of Lynch et al.² and Ritter et al.³ with regard to cardiovascular complications. However, the authors found that there was no instance of myocardial infarction in patients who were younger than 70 years of age.

The authors believe that their findings confirmed the findings reported in previous studies that, ultimately, patients who undergo bilateral total knee arthroplasty are at a slightly higher perioperative risk for cardiac complications, despite similar preoperative comorbidities. They found no difference in the outcome measures, including deep venous thrombosis, infection, and gastrointestinal bleeding in association with bilateral total knee arthroplasty.

The authors point out that there are potential weaknesses of their study, including information bias and lack of a control group, but their study is strengthened because it is an evaluation of a consecutive, nonselected series of patients.

They suggest that patients who undergo bilateral simultaneous total knee arthroplasty are at a slightly increased risk for perioperative cardiovascular, pulmonary, and neurological complications. However, they further state that it is assumed that patients will also be willing to accept the slightly increased surgical risk if it is likely to minimize the recovery period, the ultimate hospitalization time, and the time until pain relief.

Ultimately, it is the patient's choice to determine whether to undergo simultaneous bilateral or staged unilateral procedures for bilateral disease. Certainly, however, it is the physician's duty to provide information regarding the risks and benefits so that consent will be truly "informed." I believe this article provides further information that will be of great value in counseling patients as they make this very important decision.

*The author did not receive grants or outside funding in support of his research or preparation of this manuscript. The author received payments or other benefits or a commitment or agreement to provide such benefits from a commercial entity (consultant for DePuy and Zimmer). No commercial entity paid or directed, or agreed to pay or direct, any benefits to any research fund, foundation, educational institution, or other charitable or nonprofit organization with which the author is affiliated or associated.

References

1. Weinstein J. The Dartmouth atlas of musculoskeletal health care. Wennberg J, editor. Chicago: AHA Press; 2000. p 60.
2. Lynch NM, Trousdale RT, Ilstrup DM. Complications after concomitant bilateral total knee arthroplasty in elderly patients. Mayo Clin Proc. 1997;72:799-805.
3. Ritter M, Mamlin LA, Melfi CA, Katz BP, Freund DA, Arthur DS. Outcome implications for the timing of bilateral total knee arthroplasties. Clin Orthop. 1997;345:99-105.