Background

Genital numbness and erectile dysfunction in cyclists may result from repeated perineal impacts on the bicycle saddle (micro-trauma) that occur during routine cycling.

Aim

To evaluate the relationship between oscillation forces and perineal pressures among cyclists in a simulated laboratory setting.

Methods

Participants were fit to a study bicycle to ensure all cyclists had the same torso angle (60 ± 1 degree) and maximum knee angle (150 ± 1 degree). A lever system was used to generate oscillation events of 3 progressively increasing magnitudes. Perineal pressure was continuously measured using a pressure sensor on the bicycle saddle. This process was carried out in each of the following conditions: (1) stationary (not pedaling) with the standard seatpost, (2) pedaling with standard seatpost, (3) stationary with seatpost shock absorber, and (4) pedaling with seatpost shock absorber.

Outcomes

We compared perineal pressure changes during oscillation events in the stationary and pedaling states, with and without the seatpost shock absorber.

Results

A total of 39 individuals were recruited (29 men and 10 women). As the amount of oscillation increased from an average of 0.7g (acceleration due to Earth's gravity) to 1.3g, the perineal pressure increased from 10.3% over baseline to 19.4% over baseline. There was a strong linear relationship between the amount of oscillation and increase in pressure (r² = 0.8, P < .001). A seatpost shock absorber decreased the impact of oscillation by 53% in the stationary condition. Men and women absorbed the majority of shock in areas corresponding to pelvic bony landmarks.

Conclusion

This study represents one of the first characterizations of cycling-associated perineal micro-trauma in a laboratory setting. We found a strong linear relationship between oscillation magnitude and perineal pressure during cycling, which was mitigated by a seatpost shock absorber. The use of shock absorption in bicycle design may reduce perineal micro-trauma and potentially improve cycling-associated perineal numbness and erectile dysfunction. Sanford T, Gadzinski AJ, Gaither T, et al. Effect of Oscillation on Perineal Pressure in Cyclists: Implications for Micro-Trauma. Sex Med 2018;6:239-247.

Aims and objectives

Percutaneous nephrolithotomy (PCNL) remains an effective treatment for large stones. When nephrostomy tube (NT) is left post operation, antegrade urine flow is often confirmed with antegrade nephrostography (ANG) before tube removal. We compare methylene blue (MB) test combined with NT capping trial against ANG to assess antegrade urine flow after PCNL.

Materials and methods

One hundred one consecutive patients undergoing PCNL were prospectively enrolled between 7/2014 and 4/2015. An NT cap was placed the morning of postoperative day 1 (POD1). Failure was defined as need to uncap the NT for any reason. Two hours after capping, 7cc MB was injected into the NT. Positive MB test was defined as presence of blue per bladder Foley. ANG was then performed to assess antegrade urine flow. NTs were removed before discharge home when antegrade flow was documented. Primary outcomes included presence of antegrade flow on ANG and NT removal before discharge home. Receiver operating characteristic (ROC) and areas (Area under the ROC [AUC]), as well as Cohen's kappa coefficient (κ), were calculated comparing agreement of capping trial, MB, and ANG with NT removal.

Results

One hundred one subjects were included in this analysis. 52.9% were left-sided surgeries and 60.4% utilized lower pole punctures. On ROC areas evaluating tests for agreement with NT removal before discharge, MB AUC 0.71 (95% CI 0.60-0.83), capping trial AUC 0.66 (95% CI 0.57-0.75), combed capping trial and MB AUC 0.72 (95% CI 0.61-0.84), and ANG AUC 0.78 (95% CI 0.68-0.88). In predicting NT removal, ANG performed better than capping trial alone (p = 0.042), but no differences were seen between MB and ANG (p = 0.229), combining the capping trial with MB test and ANG (p = 0.266) or combined testing and MB alone (p = 0.972).

Conclusions

Combining capping trial with MB injection is similarly accurate for predicting NT removal after PCNL compared to ANG. Capping trial and MB may be used in combination to obviate the need for ANG.