The objective of this study was to anatomically describe the relationship of penile intracavernosal pillars to penile surgery, specifically corporal dilation during penile prosthesis placement. Corpora cavernosa from four embalmed male cadavers were dissected and subjected to probe dilation. Corpora were cross-sectioned and examined for the gross presence and location of pillars and dilated spaces. Infrapubic penile prosthesis insertion was performed on one fresh-frozen cadaveric male pelvis, followed by cross-sectioning. A single patient had intracavernosal pillars examined intraoperatively during Peyronie’s plaque excision and penile prosthesis insertion. Intracavernosal pillars were identified in all cadavers and one surgical patient, passing obliquely from the dorsolateral tunica albuginea across the sinusoidal space to the ventral intercorporal septum. This delineated each corpus into two potential compartments for dilation: dorsomedial and ventrolateral. Dorsal dilation seated instruments and prosthetics satisfactorily in the dorsal mid glans and provided additional tissue coverage over weak ventral areas of the tunica albuginea, while ventrolateral dilation appeared to result in ventral seating and susceptibility to perforation. Intracavernosal pillars are an important anatomic consideration during penile prosthesis placement. Dorsal dilation appears to result in improved distal seating of cylinder tips, which may be protective against tip malposition, perforation or subsequent erosion.
Cadaveric studies using gross and microscopic dissection, as well as light and electron microscopy, have contributed significant knowledge regarding the three-dimensional structure and function of the human penis and its tissues.1, 2 Though hemodynamics clearly have a major role in physiologic erections and penile rigidity, anatomic properties are another key component. Engineering analyses have shown that tissue mechanical characteristics and geometry are the principal factors in determining penile buckling forces, an essential property of penile function during penetrative intercourse.3, 4, 5
Mechanical properties of the penis are due to the tunica albuginea, a multi-layered structure that is responsible for both the flexibility and rigidity of the penis. Cadaveric microscopy studies have shown the tunica to be composed of an irregular, latticed network of elastic fibers on a collagen framework.6 Structurally, the tunica albuginea contains two principal layers: an inner circular layer that contains and supports the erectile tissue within the corpora cavernosa and corpus spongiosum, and an outer longitudinal layer that covers only the corpora cavernosa and extends from the glans penis to the proximal crura.1 Anatomic studies and cadaveric dissections by Brock et al.7 in 1997 revealed additional intracavernous ‘pillars’ or ‘struts’ that radiate from the inner tunica at about the 2 and 10 o’clock position to the ventral intercorporal septum. These pillars are thought to augment the septum and provide essential geometric support to erectile tissue. In an observational study of cadavers by Hsu et al.2 in 2004, serial cross-sectioning revealed that these intracavernosal pillars were a direct continuation of the inner circular layer of the tunica albuginea, and became larger and more prominent within the distal corpus cavernosum. This additional support structure may provide strength against penile buckling forces and facilitate distal stability for intromission.
These advances in anatomical understanding provide an important foundation for penile surgery, including interventions for Peyronie’s disease and erectile dysfunction. In this study, we sought to identify the presence of intracavernosal pillars in human cadaveric dissections and to identify their involvement in proper corporal dilation and placement of penile prosthesis. We hypothesized that lack of knowledge of these intracavernosal pillars can lead to poor distal seating of a prosthesis and/or intraoperative complications such as urethral perforation during distal corporal dilation.
Materials and methods
Dissections were carried out in a cadaveric lab on either fresh-frozen or embalmed cadaveric pelvises. None of the cadaveric specimens had previous penile, urethral, scrotal or inguinal surgery. All cadavers were ethically approved by our institution for use in surgical training and/or research. Principles of the Helsinki Declaration were followed for all human research, and written, informed consent was obtained for the use of all patient-derived images. Three surgeons performed all of the dissections. All surgeons have a subspecialty practice in andrology and regularly perform surgical procedures for Peyronie’s disease and erectile dysfunction including penile prostheses. In addition to cadaveric dissections, intraoperative images were obtained in a single patient to demonstrate how intracavernosal pillars may appear during penile surgery. Ultrasound images were also obtained to demonstrate the sonographic appearance of intracavernosal pillars, and was performed using 18 MHz linear-array transducer in B-mode imaging after pharmacologic induction of erection by intracavernosal injection.
In embalmed cadavers, the penis was bisected longitudinally in the midline along the intercavernosal septum. Corpora were then dilated both dorsally and ventrolaterally with probes until resistance was met at the distal end of the corpora. Serial cross sections were then taken of each corpus cavernosum to identify the gross presence and location of intracavernosal pillars.
In the fresh cadaver, a Foley catheter was placed into the bladder and an infrapubic transverse incision was made; dissection proceeded as a standard infrapubic approach to penile prosthesis placement.8 Bilateral 2-cm corporotomies were made in the proximal dorsal corpora cavernosa. Corporal dilation was performed with the Furlow instrument and passer, with an effort made to exert dorsal force on the dilator instrument during passage and not to exert any force toward the urethra. Next, a circumcision incision was made, the penile skin was degloved, and bilateral distal corporotomy windows were made on the dorsum to identify the location of the Furlow instrument in relation to any intracavernosal pillars. The distal penis was then amputated transversely to examine intracavernosal pillars and the previously dilated channel in a cross-sectional view.
In men with end-stage erectile dysfunction and significant concomitant penile shortening, we perform penile prosthesis placement with a Modified Sliding Technique for reconstructive length restoration.9, 10 This is reserved for cases of pathologic loss of penile length due to Peyronie’s disease, radical prostatectomy, long-standing severe erectile dysfunction with fibrosis and androgen deprivation/radiotherapy. In this technique, the penis is degloved to the level of the penoscrotal junction.11 Peri-urethral mobilization of Buck’s fascia and the neurovascular bundle is carried out from 2 cm proximal to the coronal margin to the penoscrotal junction. After excision of the Peyronie’s plaque, the penile prosthesis is inserted via ventral corporotomy below the penoscrotal junction. After corporal dilation but prior to prosthesis insertion, the corpora can be viewed cross-sectionally through the plaque excision site to identify the location of the dilated channel in relation to any intracavernosal pillars. The cylinders are then placed in the dorsomedial compartment of each corpus above the pillars to the level of the mid glans. The defect at the level of the plaque excision can be covered with graft material or by direct replacement of Buck’s fascia without graft. The proximal corporotomies are closed in a standard manner.
Ultrasound images were obtained to demonstrate erectile penile anatomy, and a representative transverse view is shown in Figure 1a. Intracavernosal pillars are seen passing obliquely from roughly the 2 o’clock position to the ventral intercorporal septum. An illustrated version of the penile cross-sectional anatomy is shown in Figure 1b. Intracavernosal pillars are seen to form predominant bands crossing the network of sinusoids that make up the corporal erectile tissue, and are continuous with the inner circular layer of the tunica albuginea. The oblique direction and relative thickness of the pillars in relation to surrounding sinusoidal tissue effectively delineate each corporal body into two potential areas for dilation during penile prosthesis surgery: a dorsomedial ‘Compartment A’ and a ventrolateral ‘Compartment B’ (labeled in Figure 1).
Embalmed cadaveric dissection was performed in four male cadavers. Probe dilation of a right corpus cavernosum in Compartment A (dorsomedial to the pillars) is shown in Figure 2a and results in seating of the probe within the distal dorsal glans. Alternatively, probe dilation in the ventrolateral Compartment B guides the probe toward the weaker, thinner ventral portion of the tunica albuginea, predisposing to potential perforation (Figure 2b). Dilation of Compartment A appeared to better seat the probe tip at the dorsal mid glans when compared with dilation in the ventrolateral area. These findings were consistent across all four cadaveric studies. Corpora were then incised transversely, as shown in Figure 3a. In Figure 3b, a cross-sectional view of a single right corpus cavernosum is shown with the presence of an intracavernosal pillar. Serial cross-sectioning from proximal to distal demonstrated that discretely visible oblique pillars first begin to appear in the distal half of the corpora and continue until the cavernosal tip. Pillars were found in all eight corporal bodies in four cadaveric penises. An illustrated version of the layered penile anatomy with viewing window is shown in Figure 3c.
Dissection and penile prosthesis placement was carried out in a single fresh-frozen cadaver. Figure 4 shows the presence of the Furlow instrument within the right corpus cavernosum, as viewed through a distal corporal incision window. Through this window, one can see the Furlow instrument in the dorsomedial Compartment A of the right corpus cavernosum. The ventromedial Compartment B tissue is seen compressed ventrolaterally. Deep transverse incision on the contralateral (left) side shows the presence of the oblique intracavernosal pillar within the non-dilated left corpus cavernosum (Figure 5). A pillar has been dissected free in Figure 6 to demonstrate its tensile strength, and the structure can be seen in a full cross-sectional view of the amputated cadaveric penis.
Over 50 cases of inflatable penile prosthesis placement with Modified Sliding Technique procedure have been performed in our institution for the management of erectile dysfunction with debilitating penile curvature or shortening. During our dissection, the intracavernosal pillars are readily identified. In a patient with Peyronie’s disease and 80˚ dorsal curvature, corporal anatomy was documented intraoperatively. In Figure 7a, the patient’s severe dorsal curvature is seen during an artificial erection; the urethra and the dorsal neurovascular bundle within Buck’s fascia have been fully mobilized. A planned line of incision is drawn. In Figure 7b, the incision has been made for penile straightening and lengthening. In Figure 7c, the dilated left and right corpora cavernosa are shown. On the left side, an intracavernosal pillar appears as an oblique white band, and the dorsomedial space adjacent to it has been dilated and ready for prosthesis insertion.
The human penis is composed of three cylindrical structures of erectile tissue: the paired corpora cavernosa and the corpus spongiosum. The corpora cavernosa are covered in the multi-layered tunica albuginea, which surrounds the cavernosal sinuses and gives off additional intracavernosal pillars to provide geometric support to these tissues. The tissue mechanical properties and geometry of the corpora are important structurally and functionally for penile physiology, and are also important considerations for the urologist in approaching penile surgery, including implantable penile prosthesis. Indeed, there has been renewed interest in recent years to return to basic anatomical considerations in the fine tuning of penile prosthetic devices.12 These advances have been made to increase device functionality and ease of use for patients, to decrease surgical complications during prosthesis surgery, and even to improve the anatomic fit and proper seating of these devices.13
There is precedent for the study of tunical anatomy and its relevance to implantable penile prosthesis. A 1994 study by Hsu et al.14 involving seven human cadavers examined the variability of tunica albuginea thickness. Mean tunical thicknesses at the 7, 9 and 11 o’clock positions of the right corpus cavernosum were 0.8 mm, 1.2 mm and 2.2 mm, respectively, and these differences were statistically significant (all P⩽0.018). Measurements at mirror image locations on the left side were nearly identical. This shows a variation of nearly threefold between the thinnest and thickest portions of the tunica albuginea. This decreased thickness correlated strongly with breaking point pressure in response to stress (r=0.911, P=0.0001), which was weakest at the 7 o’clock position. The authors concluded that the ventral groove between 5 and 7 o’clock lacks coverage by longitudinally directed tunical fibers, and therefore appears to be a vulnerable area that correlates clinically with the most common site of prosthesis extrusion. A review of the current prosthetic literature revealed all instances of impending cylinder erosion presented with the cylinder tip in the ventral location of the penile skin, glans penis or urethra, whereas no supporting evidence of corresponding dorsal erosions could be identified.15 This supports an anatomical basis for the observed common areas for this complication to occur.
Distal corporal perforation is typically defined as an intraoperative complication, while erosion is a term usually reserved for subsequent extrusion identified after surgery.16 Cases of intraoperative distal perforation are rarely reported in the literature, though we suspect they may be underreported because if observed, the procedure is often immediately aborted and no prosthesis is inserted.17 This may result in lack of inclusion in many prosthesis cohorts. Alternatively, such injuries may go unrecognized at the time of surgery, and thus may be subsequently reported as erosions. In some instances, malpositioned cylinder tips are visible covered only by a thin layer of distal penile skin. These are commonly referred to as impending erosions (example shown in Figure 8). The literature indicates an overall rate of distal erosion or impending erosion of about 1–11%.18
There are several described techniques to surgically correct and salvage such erosions or impending erosions utilizing synthetic windsock or distal corporoplasty.19 The most often utilized repair is a distal corporoplasty as described by Carson20 and Mulcahy,21 which involves reseating the cylinder in a more dorsal and secure position ‘by creating a new cavity for the cylinder behind the back wall of the fibrotic sheath containing it.’ We believe our anatomic study suggests that this surgical correction effectively involves reseating the cylinder from the much weaker ventrolateral side of the corporal intracavernosal pillars (Compartment B) to a position on their dorsomedial side (Compartment A). Previously, most authors believed these impending distal erosions to be due to ‘microperforations’ created during dilation of the distal corpora cavernosa.22 According to this theory, as the patient uses the device postoperatively, the tip of the cylinder insinuates itself in the small perforation and the erosion becomes evident. Our anatomic findings related in the current study allow us to postulate on another cause of impending cylinder erosion: incorrect seating of the distal prosthesis in relation to intracavernosal pillars.
We lend credence to this idea by identifying the previously described intracavernosal pillars in human cadaveric penises and during intraoperative surgical procedures. These pillars functionally divide each corpus cavernosum into two distinct channels, ‘Compartment A’ and ‘Compartment B,’ as shown in Figure 1. When undergoing corporal dilation for penile prosthesis insertion, ventrolateral dilation of Compartment B may result in guiding the dilator and subsequent prosthesis toward the 5 or 7 o’clock position, which is structurally the thinnest portion of the tunica albuginea with the weakest breaking point pressure and area of least resistance. In our study of human cadaveric penises, dilation ventrolaterally to the intracavernosal pillars appeared vulnerable to perforation with gentle pressure. Even if immediate gross or microscopic perforation is not encountered, prosthesis seating in this space may predispose to impending erosion by chronic exposure of the cylinders to this weak area during sexual activity and other periods of device inflation. Alternatively, exertion of dorsal pressure to dilate Compartment A was shown to compress Compartment B tissue ventrally, providing additional thickness and tissue coverage over this weak ventral area. This may hypothetically protect against perforation or erosion.
Other studies have made recent attempts to anatomically analyze distal prosthesis seating to minimize the risk of supersonic transporter (SST) deformity or hypermobile glans, a problem that can occur in up to 10% of cases.18 This deformity can be quite bothersome to patients and often requires an additional procedure for correction.23, 24 In 2013, Hakky et al.13 published a study of two human cadavers using three-dimensional imaging techniques of corporal casts. They concluded that the newer, more blunted silicone tip of the Titan (Coloplast Corp, Minneapolis, MN, USA) more closely approximates the shape of the distal corpus cavernosum than previous models and may result in more anatomic seating. In addition to prosthesis shape, surgical technique is important in proper distal seating. Incomplete distal corporal dilation, or simple undersizing of the prosthesis, may contribute to supersonic transporter (SST) or hypermobile glans. In our surgical experience, we have found dorsal dilation to result in more satisfactory distal seating of the prosthesis tip within the glans penis. We believe the dorsomedial compartment allows for more complete distal dilation with lower risk of perforation. Lower incidence of supersonic transporter (SST) deformity or hypermobile glans may thus be another potential benefit of mindful corporal dilation that takes into account the anatomical consideration of intracavernosal pillars.
Ultimately, the surgical implications of these pillars will require additional confirmatory studies in live patients. Prospective studies or at least case–control comparisons between cohorts are needed to demonstrate reduced incidence of perforation, erosion and cylinder malposition with this technique. However, comparing techniques is difficult with current retrospective data because we suspect that many surgeons are not aware that these two channels exist within the distal corpora. The present study chiefly serves to corroborate the presence of oblique pillars in the distal corpus cavernosum, and to establish how they structurally compartmentalize each corpus into two distinct channels for dilation and penile prosthesis placement. Dilation of the space ventrolateral to these pillars appears to guide dilators toward the weakest area of the tunica albuginea near the 5 to 7 o’clock position. Dilation of the dorsomedial space appears to guide dilators toward the distal glans and displaces additional tissue coverage over the weak area of the tunica albuginea, which we hypothesize may be protective against erosion and urethral injury. These distal channels may also have potential significance in the distal seating of prosthesis within the glans penis, affecting the incidence of supersonic transporter (SST) deformity. Further studies will be necessary to confirm these hypotheses and the clinical effect of alternate dilation channels on long-term outcomes of penile prosthesis implantation.
Hsu G, Brock G, Martinez-Pineiro L, Nunes L, von Heyden B, Lue T . The three-dimensional structure of the tunica albuginea: anatomical and ultrastructural levels. Int J Impot Res 1992; 4: 117–129.
Hsu GL, Hsieh CH, Wen HS, Hsu WL, Wu CH, Fong TH et al. Anatomy of the human penis: the relationship of the architecture between skeletal and smooth muscles. J Androl 2004; 25: 426–431.
Udelson D, Nehra A, Hatzichristou DG, Azadzoi K, Moreland RB, Krane J et al. Engineering analysis of penile hemodynamic and structural-dynamic relationships: Part I–Clinical implications of penile tissue mechanical properties. Int J Impot Res 1998; 10: 15–24.
Udelson D, Nehra A, Hatzichristou DG, Azadzoi K, Moreland RB, Krane RJ et al. Engineering analysis of penile hemodynamic and structural-dynamic relationships: Part III–clinical considerations of penile hemodynamic and rigidity erectile responses. Int J Impot Res 1998; 10: 89–99.
Udelson D, Nehra A, Hatzichristou DG, Azadzoi K, Moreland RB, Krane RJ et al. Engineering analysis of penile hemodynamic and structural-dynamic relationships: Part II–clinical implications of penile buckling. Int J Impot Res 1998; 10: 25–35.
Hsu GL, Brock G, von Heyden B, Nunes L, Lue TF, Tanagho EA . The distribution of elastic fibrous elements within the human penis. Br J Urol 1994; 73: 566–571.
Brock G, Hsu GL, Nunes L, von Heyden B, Lue TF . The anatomy of the tunica albuginea in the normal penis and Peyronie's disease. J Urol 1997; 157: 276–281.
Graham SD, Keane TE, Glenn JF . Glenn's Urologic Surgery, 7th edn. Wolters Kluwer Health/Lippincott Williams & Wilkins: Philadelphia, PA, USA, 2010.
Egydio PH, Kuehhas FE . Penile lengthening and widening without grafting according to a modified 'sliding' technique. BJU Int 2015; 116: 965–972.
Egydio PH, Kuehhas FE, Valenzuela RJ . Modified sliding technique (MoST) for penile lengthening with insertion of inflatable penile prosthesis. J Sex Med 2015; 12: 1100–1104.
Valenzuela R . IPP insertion and vasectomy using a single sub-coronal incision. Video J Prosthetic Urol 2015; 2: 046.
Hakky TS, Wang R, Henry GD . The evolution of the inflatable penile prosthetic device and surgical innovations with anatomical considerations. Curr Urol Rep 2014; 15: 410.
Hakky TS, Ferguson D, Spiess PE, Bradley P, Lue TF, Carrion RE . Three-dimensional mapping and comparative analysis of the distal human corpus cavernosum and the inflatable penile prosthesis. Asian J Androl 2013; 15: 567–570.
Hsu GL, Brock G, Martinez-Pineiro L, von Heyden B, Lue TF, Tanagho EA . Anatomy and strength of the tunica albuginea: its relevance to penile prosthesis extrusion. J Urol 1994; 151: 1205–1208.
Wilson SK . Postoperative pitfalls and their solutions In: Pearls, Perils and Pitfalls of Prosthetic Urology. Calvert McBride Publishing: Fort Smith, AR, USA, 2008 pp 45.
Wein AJ, Kavoussi LR, Campbell MF (eds). Campbell-Walsh Urology. 10th edn. Elsevier Saunders: Philadelphia, PA, USA, 2012.
Bettocchi C, Ditonno P, Palumbo F, Lucarelli G, Garaffa G, Giammusso B et al. Penile prosthesis: what should we do about complications? Adv Urol 2008; 573560.
Sadeghi-Nejad H . Penile prosthesis surgery: a review of prosthetic devices and associated complications. J Sex Med 2007; 4: 296–309.
Carson CC, Noh CH . Distal penile prosthesis extrusion: treatment with distal corporoplasty or Gortex windsock reinforcement. Int J Impot Res 2002; 14: 81–84.
Carson CC . Repair of distal extrusion of a penile prosthesis. Contemp Urol 1998; 10: 13–17.
Mulcahy JJ . Distal corporoplasty for lateral extrusion of penile prosthesis cylinders. J Urol 1999; 161: 193–195.
Henry GD, Laborde E . A review of surgical techniques for impending distal erosion and intraoperative penile implant complications: part 2 of a three-part review series on penile prosthetic surgery. J Sex Med 2012; 9: 927–936.
Mulhall JP, Kim FJ . Reconstructing penile supersonic transporter (SST) deformity using glanulopexy (glans fixation). Urology 2001; 57: 1160–1162.
Morey AF . Reconstructing penile supersonic transporter (SST) deformity using glanulopexy (glans fixation). J Urol 2005; 174: 969.
We would like to thank our illustrator, Vanessa Dudley, for significant contributions to this work. No research support or funding was received in connection with this study.
No research support or funding was received in connection with this study. Drs Pagano, Weinberg, Deibert, Alukal, Zhao, Egydio and Mr Hernandez have no conflict of interest. Dr Wilson reports consultation fees and non-financial support from Abreon, Boston Scientific Corp., Coloplast Corp., Neotract and Sontec Instruments outside of the submitted work. Dr Valenzuela reports consultation fees and non-financial support from Boston Scientific Corp., Coloplast Corp. and Neotract outside of the submitted work.
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Pagano, M., Weinberg, A., Deibert, C. et al. Penile intracavernosal pillars: lessons from anatomy and potential implications for penile prosthesis placement. Int J Impot Res 28, 114–119 (2016). https://doi.org/10.1038/ijir.2016.12
Evolution of techniques for aesthetic penile enlargement during prosthesis placement: a chronicle of the Egydio non-grafting strategy
International Journal of Impotence Research (2020)