Timing of bariatric surgery does not reduce TKA complication risk

Morbid obesity is associated with a higher complication rate in total knee arthroplasty (TKA). So scheduling bariatric surgery for weight loss prior to TKA seems to make sense. But according to study data presented by Erik P. Severson, MD, patients who undergo bariatric surgery and TKA have similar elevated rates of perioperative complications, regardless of the temporal relationship between the two surgeries.

The researchers retrospectively reviewed 125 patients (99 females, 26 males) who had undergone both bariatric surgery for weight loss (gastric banding or gastric bypass) and TKA from 1996 through mid-2008 at a single institution. No patients were lost to follow-up, which ranged from 22 months to 14 years. Patients who had undergone unicompartmental arthroplasty were excluded.

In an attempt to identify an optimal temporal relationship between the two surgeries, researchers divided the patients into the following groups:

  • Group 1 – TKA prior to bariatric surgery (n = 39; mean age = 55.5 years, range: 41 to 71 years; mean body mass index (BMI) = 43.1, range: 32.4 to 58)
  • Group 2 – TKA 2 years or less after bariatric surgery (n = 25; mean age = 59.3 years, range: 43 to 71 years; mean BMI = 37.9, range: 23.9 to 58.8)
  • Group 3 – TKA more than 2 years after bariatric surgery (n = 61; mean age = 59 years, range: 46 to 79 years; mean BMI = 38.5, range: 24.2 to 90.5)

Outcomes for each of the three groups were also compared to those for 17,784 primary TKAs performed over a 23-year period at the institution.

High complication rates
“We reviewed hospital and clinic charts looking for acute problems that occurred in the immediate perioperative period,” said Dr. Severson. Additional study end points included surgical time, tourniquet time, transfusion rates, revision rates, and hospital length-of-stay (LOS).

The overall complication rate was 15.2 percent among the 125 knees, which was higher than the complication rate among the historic control group. Although there was a trend toward a higher complication rate in Group 1, the authors noted no significant difference in the 90-day complication rate between the groups in a pair-wise comparison (Table 1).

The average surgical time for Group 3 was significantly less compared to Group 1 (p < 0.001) and Group 2 (p = 0.022). The average tourniquet time for Group 3 was also significantly less compared to Group 1 and Group 2 (57.6 minutes, 76.9 minutes, and 90.3 minutes, respectively).

None of the patients in Group 1 required transfusions, although 3 patients (12 percent) in Group 2 and 6 patients (9.84 percent) in Group 3 required transfusions. The overall revision rate for all patients was 5.6 percent, with no significant differences among the groups. The hospital LOS was also similar among the groups.

“Although the surgical time was less in Group 3 and transfusion rates were lower in Group 1, patients across all groups experienced similar elevated rates of perioperative complications, regardless of the temporal relationship between bariatric surgery and TKA,” Dr. Severson said.

The authors admit that the study may have been underpowered and therefore unable to show a difference in the complication rates adequately. Another weakness was that patients in the study did not undergo preoperative nutritional screening.

Despite the limitations, “patients undergoing TKA who fit the profile of those in this study should be advised that they are at increased risk for the development of complications,” said Dr. Severson. “Based on our findings, bariatric surgery will not decrease the risk.”

Dr. Severson’s coauthors of “Total Knee Arthroplasty in Morbidly Obese Patients Treated with Bariatric Surgery: A Comparative Study,” include James A. Browne, MD; Jasvinder Singh, MD; Robert Trousdale, MD; Michael Sarr, MD; David Lewallen, MD.

Disclosure information: Drs. Severson and Browne—no conflicts; Dr. Singh—Savient, URL pharma, EuroRSG, Novartis, Takeda, Journal of Clinical Rheumatology, BMC Musculoskeletal Disorders; Dr. Trousdale—DePuy, a Johnson & Johnson Company, Wright Medical Technology, Inc.; Dr. Lewallen—Orthosonics, Osteotech, Zimmer, Clinical Orthopaedics and Related Research, American Association of Hip and Knee Surgeons, American Joint Replacement Registry, Hip Society, MidAmerica Orthopedic Association, Orthopaedic Research and Education Foundation; Dr. Sarr—no information.

Prepared by Maureen Leahy, assistant managing editor for AAOS Now.