1. Cordon, Billy H., Eid, J. Francois]
Maximizing “Rigidity Factor” of Inflatable Penile Prosthesis (IPP) Results in Better Artificial Erection
Cordon, Billy H., Eid, J. Francois
Lenox Hill Hospital, New York City, New York
Introduction
It is well established that the inflatable penile prosthesis (IPP) more closely mimics expansion of the corporal bodies during erection compared to the malleable prosthesis. Classic teaching regarding placement of IPP supports the notion of using rear tip extenders (RTE) to improve mechanical survival by allowing tubing to come through the corpora more directly to the pump.
Results
Adding RTEs increase the non-inflatable portion of implant.
Current IPP cylinder design is a hybrid of a rigid and an inflatable implant.
A Titan cylinder has a 5cm rigid non-inflatable portion.
Conclusions
In normal erection, full expansion of the corpus cavernosum produces an erection well buttressed to the pelvic ramus.
Loosening over time of the pseudocapsule over the rigid portion of the implant will leads to instability, droop and wobble of erection.
Use of RTEs in our experience will with time lead to diminished erection quality.
Despite lack of objective data proving this observation, which would be difficult and impractical, we affirm that RTEs should be avoided in order to maximize penile implant support.
This is in contrast to classic teaching.
Maximizing inflatable length leads to higher Rigidity Factor and may improve durability of high quality artificial erection and subsequently patient satisfaction.
Adding a 2 cm Rear Tip Extender will decrease the ratio of live cylinder to total length and therefore decrease the rigidity factor for that cylinder.
Aim
In order to highlight that use of RTEs disregards the benefits of providing the crus with inflatable cylinders, we propose a novel concept “Rigidity Factor,” (RF) and argue that avoidance of RTEs is preferred when possible with an expectation of higher long-term patient satisfaction.
Method
We defined Rigidity Factor for a given cylinder as a ratio between the live (inflatable) portion of cylinder over the total length.
The 3-piece Coloplast Titan® IPP was analyzed.
For a given cylinder length there is a maximum Rigidity Factor. Use of RTEs decreases the Rigidity Factor.
Rigidity Factor: Ratio of inflatable live portion of inflatable cylinder
over total cylinder length with and without RTE
Total Cylinder
Length
Live Cylinder
Rigidity Factor Maximum
1 cm RTE
2 cm RTE
3cm RTE
28 cm
23cm
0.82
0.78
0.75
0.71
26 cm
21cm
0.81
0.77
0.73
0.61
24cm
19cm
0.79
0.67
22cm
17cm
0.68
0.64
20cm
15cm
0.7
0.65
0.6
28 cm
Maximizing RF leads to high quality artificial erection. Titan XL 26 cm depicted.
26 cm
24 cm
22 cm
20 cm