Background: Outpatient knee surgery has come to involve increasingly complex procedures. The authors present observational data from a nerve block algorithm designed for the care of outpatients undergoing knee surgery. The aim of this report is to demonstrate differences in pain and unplanned hospital admission associated with surgical complexity and nerve blocks used.
Methods: Day-of-surgery outcomes were studied for 1,200 consecutive outpatients undergoing routine arthroscopy or one of six complex outpatient knee procedures. Nerve blocks were administered on the basis of anticipated pain from open incisions in the femoral and sciatic nerve distributions. Regression analysis was used to determine factors associated with postoperative pain and unplanned hospital admissions, and patients were categorized as having received femoral and sciatic nerve blocks (FSB), femoral nerve block only (FNB), or no nerve blocks.
Results: Patients undergoing more complex (vs. less invasive) knee surgery were at greater risk for pain (P </= 0.004), whereas the use of FSB (vs. FNB or no block) was associated with less pain (P < 0.01). When no nerve blocks were used, more complex (vs. less invasive) knee surgery was associated with a 10-fold greater risk of hospital admission (P = 0.001). In the regression analyses, more complex surgery (P < 0.001) was associated with increased risk of admission, and the use of FNB or FSB (vs. no block) was associated with a 2.5-fold reduction in unplanned admissions (P = 0.009).
Conclusions: For complex knee surgery, the use of FSB was associated with less pain; the use of FNB or FSB (vs. no block) was associated with fewer hospital admissions.