Vancouver Foot and Ankle WNS (Wound, Nerve, and Systemic) Classification System for Foot and Ankle Orthopedic Surgery

Foot Ankle Int. 2018 Sep;39(9):1056-1061. doi: 10.1177/1071100718778022. Epub 2018 Jun 4.


Background: Adverse events require consistent recording to determine the effect of alternate treatments. This study was undertaken to evaluate the Vancouver Foot and Ankle WNS complication scale to capture complications (W: wound, N: nerve, S: systemic) to assist in outcome recording.

Methods: Interrater reliability was tested in 2 settings: (1) between 2 blinded clinicians in a live clinical setting and (2) between 8 orthopedic surgeons using case vignettes based on a retrospective analysis of 500 foot and ankle procedures performed at the Toronto Western Hospital, Department of Orthopaedics. The intrarater reliability of the WNS scale was tested in a single rater using the case vignettes. Inter- and intrarater reliability were assessed using the Fleiss and Cohen weighted kappa ( k), respectively and 95% confidence intervals (CIs). There was adequate power over 0.8.

Results: In the live clinical setting, the Cohen weighted k (95% CI) values for the W (0.935 [0.862, 1.01]), N (0.914 [0.752, 1.08]), and S (1 [1, 1]) parameters, indicating a near perfect level of agreement between raters. In the broader community of professional foot and ankle surgeons, the Fleiss k values (95% CI) had moderate agreement for the W (0.712 [0.688, 0.735]), N (0.775 [0.738, 0.811]), and high agreement for S (0.834 [0.802, 0.866]) parameters based on case vignettes. However, the Fleiss k values continued to indicate moderate to strong agreement between raters for all parameters.

Conclusions: The WNS scale provided a standardized method of measuring foot and ankle surgical complications. There was at least moderate-strong interrater agreement for all parameters measured on case vignettes and excellent concordance in the live setting.

Level of evidence: Level III, comparative series.

Keywords: classification system; foot and ankle surgery; foot and ankle surgical complications; surgical complications.

MeSH terms

  • Foot / innervation
  • Foot / surgery*
  • Humans
  • Observer Variation
  • Orthopedic Procedures / adverse effects*
  • Orthopedics*
  • Postoperative Complications / classification*
  • Retrospective Studies
  • Surgical Wound / classification