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Similar post-TKA survivorship found in obese and nonobese patient groups
In the mid-term follow-up, the investigators found three cases of early infection in the obese group.
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As obesity becomes a global epidemic, surgeons have increasingly raised concerns about performing total joint replacement on these patients.
Now, research shows comparable mid-term survivorship and satisfaction scores between obese and nonobese patients who underwent total knee arthroplasty (TKA).
“Obesity makes the surgery more difficult and you get more wound problems,” William L. Walter, MD, FRCS, PhD, said during his presentation at the 2009 Current Concepts in Joint Replacement Spring Meeting. “Obese patients get poorer range of motion, but good pain relief, and they do not wear their knees out.”
Cementless TKA
To determine the impact of obesity on TKA, Walter and colleagues reviewed the results of 535 consecutive patients who underwent a cementless primary TKA performed by two surgeons between 1995 and 2001. Nearly 30% of the patients were obese with a body mass index (BMI) greater than 30, and there were significantly more women than men in the obese group. The obese patients were also younger than those in the nonobese group (66.8 vs. 71.8 years). The patients had a mean follow-up of 6.8 years.
“There was no reduction in the patients’ BMI after they had the knee replacement,” Walter said. A Kaplan-Meier survival analysis using revision for any reason as an endpoint showed no significant differences between the obese and nonobese groups. However, the investigators found three early infections in the obese group.
Case control study
In a case control study comparing 50 obese patients and a matched cohort of 50 nonobese patients who underwent TKR, the investigators discovered a lower mean postoperative Hospital for Special Surgery (HSS) knee score in the obese group.
“The poorer scores were due to poorer function and poorer range of motion,” Walter said. The investigators also found a maximum knee flexion of 112· for the obese group and 120· in the nonobese group. They discovered no significant differences between the groups regarding patient satisfaction scores and also found good pain relief in the obese group.
Surgical considerations
Performing surgery in an obese patient can be difficult and it may be impossible to apply a tourniquet in some cases, Walter said.
“We use a different incision for obese patients,” he said. “It is longer and is either midline or perhaps based laterally to allow for easier eversion of the patella without coming into contact with the subcutaneous fat.”
Surgeons should also be aware of wound healing problems, and therefore may use special sutures or prescribe less-aggressive rehabilitation.
“We use navigation routinely and this gives us more confidence in the obese patients when it comes to alignment,” Walter said.
For more information:
- William L. Walter, MD, FRCS, PhD, can be reached at Sydney Hip & Knee Surgeons, Level 3, 100 Bay Road, Sydney, NSW, 2060, Australia; 02 8920 3388; e-mail: bill.walter@hipknee.com.au. He has no direct financial interest in any companies or products mentioned in this article.
Reference:
- Jackson MP, Sexton SA, Walter WL, Walter WK, Zicat BA. Patient obesity: A growing concern of successful TKA. Paper #37. Presented at the 10th Annual Current Concepts in Joint Replacement Spring Meeting. May 17-20, 2009. Las Vegas.