Himplant® Subcutaneous Penile Implant Improves Penile Appearance and Erectile Dysfunction After Radical Prostatectomy: A Case Series

A 4-patient case series — with manufacturer financial ties declared by 3 of 5 authors — reports high satisfaction with a subcutaneous silicone penile implant post-prostatectomy.

Journal: International Journal of Impotence Research | Published: 2024-03-05 | Type: Case Series / Review | PMID: 38443555 Authors: Valenzuela RJ (Icahn School of Medicine at Mount Sinai); Elist JJ (Cedars-Sinai, emeritus; operates James J. Elist MD, A Medical Corporation, Beverly Hills); Moon D, Cvijanovic L (James J. Elist MD, A Medical Corporation); Wilson SK (Institute for Urologic Excellence, La Quinta, CA) Funding/COI: Funding not reported. Three of five authors — Valenzuela, Elist, and Wilson — declare financial relationships with International Medical Devices, the manufacturer of Himplant®. Moon and Cvijanovic declare no conflicts; both are employed at Elist's private practice.

Summary

Four men with post-radical prostatectomy erectile dysfunction (ED) who had limited response to PDE5 inhibitors received a Himplant® subcutaneous silicone penile implant via high scrotal incision. All four reported satisfaction and improved flaccid penile appearance; erectile function was also reported as improved. The paper concludes with a recommendation that Himplant® be offered to post-prostatectomy patients frustrated by penile appearance and ED — a conclusion drawn from four cases, authored in substantial part by people financially tied to the device's manufacturer.

The Himplant® is a subcutaneous implant: it augments flaccid size by placing a silicone sleeve beneath the skin. It is not a penile prosthesis in the mechanical sense — it does not produce erections. Framing it as a treatment for ED alongside improvements in appearance conflates two distinct outcomes.

Claims

• All 4 patients reported high satisfaction via a 15-question survey (no validated instrument named)
• Increases in flaccid penile length and girth were reported in all patients
• Improved erectile function was reported post-implant (mechanism and measurement not specified in the abstract)
• No adverse events were reported in any of the 4 cases
• The paper also incorporates data from the COMPARE registry (948 men after prostate cancer treatment) showing: 3.73% of post-prostatectomy patients complained of reduced penile size vs. 0% after radiotherapy alone (p = .004); reduced penile size was associated with increased treatment regret (OR 3.37, 95% CI 1.37–8.26) and interference with close emotional relationships (OR 2.36, 95% CI 1.02–5.47)

Study Quality

A 4-patient case series is the lowest rung of clinical evidence. There is no control group, no randomization, no blinding, and no validated patient-reported outcome instrument. Follow-up duration is not specified in the available abstract. The 15-question satisfaction survey appears to be custom-designed, with no psychometric validation mentioned. Without a comparator arm, it is impossible to distinguish device effect from placebo effect, surgical attention, or simple regression to the mean.

The paper incorporates COMPARE registry data (948 patients) as background evidence for the burden of penile shortening after prostatectomy. That registry data is legitimate and from a well-described observational cohort — but it does not evaluate Himplant® and should not be conflated with evidence for the device.

Red Flags

• n = 4. This is not a study; it is a report of four surgical experiences
• Tripled-up COI: Valenzuela, Elist, and Wilson all disclose financial relationships with International Medical Devices, Himplant®'s manufacturer; Elist appears to be the device's primary clinical promoter
• Moon and Cvijanovic "declare no competing interests" but are employed at Elist's private practice — an indirect financial dependency not fully addressed
• No validated ED outcome measure (e.g., IIEF) is mentioned for the primary ED endpoint
• The device is subcutaneous — it does not mechanically produce erections — yet "improved erectile function" is listed as a finding without mechanistic explanation
• Authors conclude with a direct clinical recommendation ("we suggest Himplant® placement in patients who are frustrated") — unusual and inappropriate at this evidence level, especially given the COI
• Funding source not disclosed
• No adverse event reporting is possible in 4 cases — absence of evidence is not evidence of absence at this sample size
• COMPARE registry data is imported wholesale into a case series, lending it a scale it does not possess

Strengths

• Prospective design; patients consented and data were collected with stated intent
• The COMPARE registry data on penile shortening burden is real and relevant — this is a genuine unmet clinical problem affecting roughly 3.7% of post-prostatectomy patients
• Identifies a legitimate gap: no currently approved device specifically addresses post-prostatectomy flaccid penile appearance alongside ED
• Authors acknowledge the limitation and call for multicenter studies — though this caveat is undermined by the closing clinical recommendation

Verdict

This paper should not be used as evidence that Himplant® works. Four patients, no controls, no validated outcomes, and three authors on the manufacturer's payroll is not a foundation for clinical conclusions — let alone the recommendation the authors issue at the end. What the paper does successfully is document that penile shortening after prostatectomy carries real psychological consequences (the COMPARE data on treatment regret and relationship interference is notable), and that there is a product targeting this problem. Whether the product works, at what rate it fails, and whether it's safer than alternatives cannot be answered here. The multicenter trials the authors call for are the actual study this question needs.