Biportal endoscopic lumbar surgery: no wound dehiscence in a pooled post hoc analysis

Design

Post hoc pooled analysis of two randomised trials

Population

211 patients having single-level lumbar decompression or discectomy (108 biportal endoscopic, 103 microscopic)

Primary outcome

Wound dehiscence requiring resuturing after suture removal

Effect

0.0% vs 8.7%; OR 0.046 (95% CI 0.003 to 0.798)

This post hoc analysis pooled two randomised trials comparing biportal endoscopic spine surgery with microscopic surgery for single-level lumbar decompression or discectomy: 211 patients (108 endoscopic, 103 microscopic).

Wound dehiscence, defined as separation needing resuturing after suture removal, occurred in nine patients (4.3%), all in the microscopic group (0.0% vs 8.7%; OR 0.046, 95% CI 0.003 to 0.798). Across all patients, an incision length of 35 mm or more had the highest risk ratio (15.44). Drainage of 100 mL or more (RR 8.55) and a rise in white cell count of 2 x 10^3 per microlitre or more (RR 7.78) were also linked to dehiscence.

The authors call these hypothesis-generating findings. Nine events is a small number for a risk-factor analysis, and the trials were not designed to test dehiscence.

• Watch wounds more closely after microscopic surgery when drain output is 100 mL or more.
• Note that a longer incision (35 mm or more) was linked to dehiscence in this analysis.
• Do not choose a technique on this result alone; the trials were not designed for dehiscence.
• Document wound healing at suture removal for a more complete picture.

Why it matters

Wound problems are a small but real cost of lumbar surgery that trials rarely report.

Don't overread it

A post hoc analysis of two trials with nine events; it generates a hypothesis, not a recommendation to switch technique.

The statistics, in plain English

With zero events in one arm and nine in the other, the confidence interval for the odds ratio is very wide (0.003 to 0.798), so the true size of the difference is uncertain. Risk ratios for the risk factors rest on the same nine events.

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