Minimally Invasive Ponto Surgery Versus the Linear Incision Technique With Soft Tissue Preservation for Bone Conduction Hearing Implants: A Multicenter Randomized Controlled Trial

Abstract

Objective: To compare the surgical outcomes of the Minimally Invasive Ponto Surgery (MIPS) technique with those of the linear incision technique with soft-tissue preservation for bone-anchored hearing systems (BAHS).

Design: Sponsor-initiated multicenter, open, randomized, controlled clinical trial.

Setting: Maastricht University Medical Centre, Ziekenhuisgroep Twente and Medisch Centrum Leeuwarden, all situated in The Netherlands.

Participants: Sixty-four adult patients eligible for unilateral BAHS surgery.Interventions Single-stage BAHS surgery with 1:1 randomization to the linear incision technique with soft-tissue preservation (control) or the MIPS (test) group.

Primary and secondary outcome measurements: Primary objective: compare the incidence of inflammation (Holgers Index ≥ 2) during 12 weeks' follow-up after surgery. Secondary objectives: skin dehiscence, pain scores, loss of sensibility around the implant, soft-tissue overgrowth, skin sagging, implant extrusion, cosmetic results, surgical time, wound healing and Implant Stability Quotient measurements.

Results: Sixty-three subjects were analyzed in the intention-to-treat population. No significant difference was found for the incidence of inflammation between groups. Loss of skin sensibility, cosmetic outcomes, skin sagging, and surgical time were significantly better in the test group. No statistically significant differences were found for dehiscence, pain, and soft-tissue overgrowth. A nonsignificant difference in extrusion was found for the test group. The Implant Stability Quotient was statistically influenced by the surgical technique, abutment length, and time.

Conclusion: No significant differences between the MIPS and the linear incision techniques were observed regarding skin inflammation. MIPS results in a statistically significant reduction in the loss of skin sensibility, less skin sagging, improved cosmetic results, and reduced surgical time. Although nonsignificant, the implant extrusion rate warrants further research.

FIG. 1

Surgical techniques. A, Linear incision technique with soft-tissue preservation. (i) Linear incision. (ii) Drilling procedure. (iii) Implant installation. (iv) Closing incision line. (v) Result after skin punch. (vi) Attachment of healing cap and application of dressing. B, Minimally Invasive Ponto Surgery. (i) Skin punch. (ii) Placement of the cannula. (iii) Drilling procedure. (iv) Implant installation with installation indicator. (v) Result. (vi) Attachment of healing cap and application of dressing.

FIG. 2

Subject flow chart. Sixty-four subjects were randomized. Twenty-nine subjects in each group were included in the per protocol analysis.

FIG. 3

Primary outcome, loss of skin sensibility, and cosmetic aspects. A, Stacked bar chart for the Holgers Index scores on standard follow-up visits and the highest observed Holgers Index score. B, Box plots of loss of skin sensibility per treatment group on standard follow-up visits. C, Cosmetic outcomes at 12 weeks per treatment group. Cosmetic outcome specifics are described in Table 2.

FIG. 4

Extrusion rate and ISQ values. A, Kaplan–Meier survival plot for bone conduction hearing implants displayed per surgical technique. B, Boxplots of ISQ measurements at surgery and on standard follow-up visits. ISQ measurements are displayed for ISQ low and ISQ high per abutment length and surgical technique. ISQ indicates implant stability quotient.