Male stress urinary incontinence (SUI), the involuntary leakage of urine due to physical exertion, is commonly managed by penile clamps. However, there is currently no methodology to quantify how effectively penile clamps prevent urine leakage while preserving blood flow without relying on patient-dependent studies. Our benchtop model provides a controlled, reproducible framework for comparing penile clamp performance under simplified physiological conditions, offering comparative data on clamp efficacy. Force applied by the clamps was determined via a load cell to estimate contact stress. Separately, penile clamps were applied to foam cylinders with channels simulating the urethra and dorsal vein. The following penile clamps were used: The Cunningham Clamp, The Pacey Cuff, The Lunderg Freedom Clamp, and The Squeezer Klip. The foam-based penis model allowed us to assess urine and blood flow inhibition post-clamp application. The channels were both lined with identical latex tubing to standardize compliant wall properties given inter-individual variability in dimensions of the dorsal vein and urethra. To account for variable penile tissue resistances, low-stiffness (Foam 6) and high-stiffness (Foam 17) foams were tested. Average urine flow rates achieved in Foam 6 and 17 were within physiological range for average SUI patients (9.72 mL/s and 9.06 mL/s respectively), and a blood pressure of 51.8 mmHg was achieved using a blood substitute with viscosity of 3.7 cP. In Foam 6, no clamps caused more than 10% blood flow inhibition. However, in Foam 17, there were significantly higher levels of blood flow inhibition across almost all clamps and their settings, most notably with the Lunderg Freedom Clamp (approx. 60%). Overall, clamp efficacy was more dependent on pressure distribution via each clamp's design rather than absolute contact stress. Results were consistent with patient reviews, and mechanisms of the clamp itself, suggesting reliability and validity of the model.
Medical engineering & physics. 2026 Jul 29 [Epub ahead of print]
Tanisa Goyal, Chin Hang Ryan Chan, Christina Liu, Connie Y Chen, Aadit Walia, Abdus Sabour Shaik, Angela J Sadlowski, Zhiyuan Ding, Ethan Y Wu, Constanza Miranda, Andrew J Cohen
Biomedical Engineering, Johns Hopkins University Whiting School of Engineering, 3400 N. Charles Street, Baltimore, Maryland, 21218-2608, United States., Biomedical Engineering, Johns Hopkins University, 3400 N. Charles Street, Baltimore, Maryland, 21218-2625, United States., Texas A&M School of Engineering Medicine, 1020 Holcombe Blvd, Houston, Texas, 77030, United States., Yale School of Medicine, 333 Cedar St, New Haven, Connecticut, 06510, United States., James Buchanan Brady Urological Institute, Johns Hopkins Bayview Medical Center, 4940 Eastern Ave, Baltimore, Maryland, 21224, United States.