Korean J Anesthesiol.  2016 Feb;69(1):32-36. 10.4097/kjae.2016.69.1.32.

Can bedside patient-reported numbness predict postoperative ambulation ability for total knee arthroplasty patients with nerve block catheters?

  • 1Department of Anesthesiology, Perioperative and Pain Medicine, Stanford University School of Medicine, CA, USA. emariano@stanford.edu
  • 2Anesthesiology and Perioperative Care Service, Veterans Affairs Palo Alto Health Care System, CA, USA.
  • 3Department of Orthopaedic Surgery, Stanford University School of Medicine, CA, USA.
  • 4Surgical Service, Orthopaedic Surgery Section, Veterans Affairs Palo Alto Health Care System, CA, USA.


Adductor canal catheters offer advantages over femoral nerve catheters for knee replacement patients because they produce less quadriceps muscle weakness; however, applying adductor canal catheters in bedside clinical practice remains challenging. There is currently no patient-reported outcome that accurately predicts patients' physical function after knee replacement. The present study evaluates the validity of a relatively new patient-reported outcome, i.e., a numbness score obtained using a numeric rating scale, and assesses its predictive value on postoperative ambulation.
We conducted a retrospective cohort study pooling data from two previously-published clinical trials using identical research methodologies. Both studies recruited patients undergoing knee replacement; one studied adductor canal catheters while the other studied femoral nerve catheters. Our primary outcome was patient-reported numbness scores on postoperative day 1. We also examined postoperative day 1 ambulation distance and its association with postoperative numbness using linear regression, adjusting for age, body mass index, and physical status.
Data from 94 subjects were included (femoral subjects, n = 46; adductor canal subjects, n = 48). Adductor canal patients reported decreased numbness (median [10th-90th percentiles]) compared to femoral patients (0 [0-5] vs. 4 [0-10], P = 0.001). Adductor canal patients also ambulated seven times further on postoperative day 1 relative to femoral patients. There was a significant association between postoperative day 1 total ambulation distance and numbness (Beta = -2.6; 95% CI: -4.5, -0.8, P = 0.01) with R2 = 0.1.
Adductor canal catheters facilitate improved early ambulation and produce less patient-reported numbness after knee replacement, but the correlation between these two variables is weak.


Adductor canal block; Ambulation; Femoral nerve block; Numbness Perineural catheter; Total knee arthroplasty

MeSH Terms

Body Mass Index
Cohort Studies
Early Ambulation
Femoral Nerve
Linear Models
Nerve Block*
Quadriceps Muscle
Retrospective Studies
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