Anesthesia choice may benefit knee arthroplasty patients

By Lynda Williams, Senior medwireNews Reporter

Spinal anesthesia could reduce the risk for postoperative complications in select patients undergoing total knee arthroplasty (TKA), US researchers say.

Primary TKA patients with multiple comorbidities derive the greatest benefit from spinal anesthesia, with 30-day complication rates for those in the highest risk quintile of 15.28% with general anesthesia and 11.63% with spinal, a significant difference.

The study used primary TKA data from the American College of Surgeons National Surgical Quality Improvement Program for 2005 to 2010 for 14,052 primary TKAs, with 57.1% of procedures performed under general and 42.9% under spinal anesthesia.

Spinal anesthesia was associated with significantly shorter surgery time (96 vs 100 min) and hospital stays (3.45 vs 3.77 days) than general anesthesia.

Initial analysis indicated that spinal anesthesia was also significantly associated with a reduced risk for superficial wound infection (0.68 vs 0.92%), blood transfusion (5.02 vs 6.07%), and overall risk for complications (10.72 vs 12.34%) compared with general anesthesia.

The increased risk for complications with general anesthesia was confirmed in multivariate analysis with an odds ratio (OR) of 1.129 versus spinal anesthesia, the researchers say.

The OR for complications was 1.531 for patients aged 70-79 years versus 50-59 years, rising to 2.173 for those aged over 80 years. Women had an OR for complications of 1.531 compared with men, and Black patients an OR of 1.678 versus White patients.

Serum creatinine greater than 1.2 mg/dL, American Society of Anesthesiologists' class 3 or 4, and longer operative time also increased the risk for complications, with ORs of 1.474, 1.204, and 1.003, respectively.

But the researchers note that the study was powerful enough to detect between-group differences of less than 1% and believe these are unlikely to have much clinical significance.

"It is important to recognize that the differences in complication rates between spinal and general anesthesia are small and that general anesthesia remains a reasonable choice for many patients undergoing total knee arthroplasty," emphasize Andrew Pugely and co-authors, from University of Iowa Hospitals and Clinics in Iowa City.

The study is reported in the US edition of the Journal of Bone and Joint Surgery.

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