Intersphincteric prosthetic implants for faecal incontinence: a systematic review and exploratory pooled analysis of clinically meaningful response

Abstract

Intersphincteric prosthetic implants have emerged as a minimally invasive treatment option for faecal incontinence (FI), positioned between conservative therapies and more invasive surgical or neuromodulatory interventions. However, evidence supporting their effectiveness remains fragmented and largely nonrandomised. A PRISMA-compliant systematic review with exploratory quantitative synthesis was conducted. MEDLINE and Embase were searched from inception to August 2025, with an updated search in January 2026 for nonrandomised studies evaluating intersphincteric prosthetic implants (GateKeeper® or SphinKeeper®) in adults with FI. The primary outcome was the proportion of patients achieving a clinically meaningful response, defined as a ≥ 50% reduction in Vaizey (St Mark’s) score at ≥ 12 months. Where feasible, exploratory pooled analyses of binary responder outcomes were performed using random-effects models. Secondary outcomes, including continence severity, quality of life and complications, were synthesised narratively. Certainty of evidence was assessed using GRADE. Fourteen observational studies were included. Two studies reporting comparable binary responder outcomes at approximately 12 months ( n = 75) contributed to the primary exploratory synthesis, yielding a pooled responder proportion of 49.3% (95% CI 38.2–60.5%). A sensitivity analysis incorporating three studies reporting study-defined clinical success ( n = 129) produced a similar pooled estimate (51.9%, 95% CI 43.3–60.4%). Given the very small number of contributing studies, measures of statistical heterogeneity were uninformative, and interpretation was further limited by the nonrandomised study designs. Quality-of-life outcomes and complication rates were heterogeneous and could not be pooled quantitatively. No procedure-related mortality was reported. Exploratory quantitative synthesis suggests that intersphincteric prosthetic implantation may be associated with clinically meaningful symptom improvement in a subset of patients with faecal incontinence. However, the certainty of evidence is low, and pooled estimates should be interpreted as hypothesis-generating. Prospective comparative studies with standardised outcome reporting are required to more clearly define the role of these implants within the treatment pathway. What does this paper add to the literature? This review brings together the fragmented evidence on intersphincteric prosthetic implants for faecal incontinence and, where definitions allowed, summarises clinically meaningful responder outcomes at medium-term follow-up. It shows how limited and heterogeneous the evidence remains and identifies where comparative data are most needed.