Published 3/1/2011
Maureen Leahy

Timing of bariatric surgery does not reduce risks for TKA patients

Small study finds no optimal timing between the two procedures

Morbid obesity (body mass index greater than 30) 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 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 endpoints 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 (57.6 minutes) was also significantly less compared to Group 1 and Group 2 (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 co-authors 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.

Bottom line

  • Morbidly obese patients undergoing TKA are at risk for complications.
  • Based on the results of this this small, single-institution, retrospective study, patients who undergo bariatric surgery and TKA experience similar elevated rates of perioperative complications, regardless of when the bariatric surgery is performed.
  • Bariatric surgery prior to TKA does not reduce the complication risk to patients undergoing TKA.

Maureen Leahy is assistant managing editor for AAOS Now. She can be reached at leahy@aaos.org