Morbidity risks in simultaneous bilateral TKA

By: Maureen Leahy

By Maureen Leahy

Patients older than age 70 with a pre-existing pulmonary disorder or body mass index (BMI) greater than 30 are at increased risk for complications resulting from simultaneous bilateral total knee arthroplasty (TKA) versus unilateral TKA, according to study data presented yesterday. The bilateral group also had higher transfusion rates and a longer hospital stay.

For many patients, degenerative joint disease affects both knees. Rather than staging separate procedures that submit patients to multiple hospital admissions, two operations, repeated anesthesia, and two periods of rehabilitation, many patients and surgeons opt for simultaneous bilateral TKA.

Up to this point, however, preoperative patient factors that identify good candidates for simultaneous bilateral TKA have not been fully delineated.

“Many surgeons believe that complications increase when simultaneous procedures are performed, due to the increased operative time and blood loss under a single anesthetic,” said Vivek Mohan, MD, MS, study author. “We sought to determine if an increased risk of complications was present in simultaneous versus unilateral TKA.”

Specifically, the purpose of this study was to examine the effect of age, stratified by decade, and the presence of preoperative medical conditions on perioperative morbidity and mortality.

Patient population
The retrospective case review analyzed the preoperative, perioperative, and postoperative data of 150 patients who underwent unilateral TKA (control) and 150 patients who underwent simultaneous bilateral TKA (study). Control group surgeries were performed between 1999 and 2001 on patients aged 51 years to 87 years (mean age, 71 years). Study group surgeries occurred between 2000 and 2001 on patients aged 51 years to 90 years (mean age, 70 years). All surgeries were performed by a single board-certified orthopaedic surgeon at three different hospitals.

Each of the 300 patients had cemented TKA using a standard medial parapatellar approach, under tourniquet control. A standardized postoperative protocol consisting of thromboprophylaxis with warfarin and sequential compression devices was used on all patients. Physical therapy, including weight bearing as tolerated, quadriceps strengthening, and straight leg-raise exercises, was begun on postoperative day 1.

Comparison of preoperative conditions in the two groups was made based on the following: age, subdivided by decade into 50s, 60s, 70s, and older than 80; BMI greater than 30; and presence of preoperative pulmonary or airway disorders including allergic rhinitis, asthma, chronic obstructive pulmonary disorder (COPD), emphysema, lung cancer, laryngeal cancer, and pneumonia.

Postoperative data collected for comparison between the two groups included transfusion rate; length of inpatient hospital stay; and total number of early and late complications, including fever greater than 101 degrees, wound complications, gastrointestinal disturbances, hyperglycemia, neurovascular insult, fractures, and cardiac, neurologic, renal, or pulmonary complications. Within the bilateral TKA group, researchers also compared the complication rates of patients with preoperative pulmonary or airway disorders to those without those comorbidities.

Complication rate double
Overall, the mean complication rate was slightly greater than double in the simultaneous bilateral TKA group (0.95) as compared to the unilateral TKA group (0.45). Individual category results (
Table 1) showed the following:

  • Pre-existent pulmonary disorders: Study results showed a statistically significant association between preoperative pulmonary disorders and postoperative complications. In simultaneous bilateral TKA patients, the relative risk of complications was eight times greater than in unilateral TKA patients.
  • BMI greater than 30: Data showed a significant difference in complication rates in obese patients between the study and control groups: simultaneous bilateral TKA (0.96) versus unilateral TKA (0.44).
  • Age: Simultaneous bilateral TKA patients older than 70 years had almost 2 to 3 times as many complications as similarly aged unilateral TKA patients.
  • Transfusion rate: Patients who underwent simultaneous bilateral TKA had a transfusion rate nearly four times higher than unilateral TKA patients.
  • Length of stay: The average length of stay was 4.9 days for the simultaneous bilateral TKA group and 3.3 days for the unilateral TKA group.

Effective treatment for some
“Ultimately,” the authors wrote, “the decision to proceed with bilateral TKA should be made on an individual basis. The risks and benefits of a sequential or staged bilateral TKA should be thoroughly discussed with each patient in the clinic prior to surgery. In the properly selected patient, simultaneous bilateral TKA is a safe and effective treatment of bilateral knee arthritis.”

Dr. Mohan’s co-authors of “Unilateral versus Bilateral Total Knee Arthroplasty: Risk Factors Increasing Morbidity” include David Fabi, MD; Wayne Goldstein, MD; Jonathan Dunn, MD; and Brian Murphy, MD. Dr. Goldstein disclosed the following conflicts: Journal of Arthroplasty; DePuy, a Johnson & Johnson Company; Innomed; and Smith & Nephew. The other authors reported no conflicts of interest. A link to the abstract of their study can be found in the online version of this article, available at

Maureen Leahy is assistant managing editor for AAOS Now. She can be reached at