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Investigation of Penile Suspensory Ligaments Using Epoxy Sheet Plastination and Confocal Microscopy

By: Ross Calopedos, MD, BMed, BA, MS (Urol), FRACS (Urol), Macquarie University Hospital, Sydney, Australia; Prem Rashid, MBBS, PhD, DClinSurg, GAICD, FFSTEd, FACS, FRACS (Urol), Port Macquarie Base Hospital, Australia; Ming Zhang, MB, MMed, PhD, University of Otago, Dunedin, New Zealand | Posted on: 20 May 2024

The penile suspensory ligament (PSL) is an umbrella term for the connective tissue apparatus that maintains the prepubic position in the flaccid state. Following erection, PSL stabilization of the axial load-bearing corpora facilitates penetration and the fixed penopubic angle enables continued intercourse.

Since its initial use in bladder exstrophy reconstruction, PSL ligamentolysis has been popularized in cosmetic penis enlargement surgery (PES). PSL division allows a degree of distraction between the pubic symphysis (PS) and base of the penis and provides the illusion of a longer penis, despite corporal length remaining the same. Urologists also employ the technique as a length-restoring adjunct in the surgical management of Peyronie’s disease, erectile dysfunction (ED), buried penis, or following penile trauma or cancer resection. More recently it has been advocated for the treatment of penile dysmorphophobia, after exhausting psychological measures.1,2

Despite this, we lack a clear understanding of the anatomy being divided. PSL is usually described as having 3 components—fundiform (FL), suspensory (SL), and arcuate ligaments (ALs)—but there is no consensus on their origins and insertions, or their precise function. For the common targets of PSL division (FL/SL), every permutation of anatomical connection has been published (origin: Scarpa’s fascia, linea alba, PS; insertion: dartos or Buck’s fascia, tunica albuginea [TA]).3

Proponents of PES argue that FL/SL merely interconnects Scarpa’s and dartos fascias. They propose the AL is the main support structure of the erect penis as it connects the PS directly with the TA of the corpora. An additional fourth component, the “vertical dense ligament,” was reported in a recent cadaveric study and further supports the rationale that FL/SL can be divided without functional compromise, as the deeper ligaments are undisturbed by PES.4


Figure 1. Example of mesoscopic median sagittal epoxy plastinated slice (A) and confocal microscopy of area within box (the conjoint tendinous center of the perineal body) demonstrating connective tissue autofluorescence (B). DUS indicates distal urethral sphincter.

Table. Summary of Findings

PSL component Origin Insertion Fibrous orientation
Prepubic Musculotendinous: aponeurotic fibers of abdominal wall musculature. These fibers also contribute to Scarpa’s fascia. As such, FL is not a thickening or a continuation of Scarpa’s fascia Superficial penile fascia (dartos) Superior to inferior
Subpubic Ligamentous: fibers originate directly from pubic bone or symphyseal cartilage Tunica albuginea Fibers decussate: anterosuperior to posteroinferior (dominant portion); posterosuperior to anteroinferior (nondominant portion)
Retropubic Musculotendinous: fibers originate from the investing fascia of the urogenital diaphragm Tunica albuginea Posterior to anterior
Abbreviations: FL, fundiform ligament; PSL, penile suspensory ligament.


Figure 2. Proposed nomenclature for penile suspensory ligament anatomy.


Figure 3. Prepubic penile suspensory ligament.


Figure 4. Subpubic penile suspensory ligament.


Figure 5. Retropubic penile suspensory ligament.

Paradoxically, penile shortening following PSL division is a well-known complication. The proposed cause is cicatrization of cut ligaments or reattachment of the penile corpora to a more posterior position on PS.5 There are multiple published techniques to avoid this, using various implants or autologous tissue, yet no consensus on the optimal extent of PSL division.6 Published outcomes on length gain are also highly variable, and patient-reported outcomes are scarce. In one candid series of 42 patients, overall satisfaction following PSL division was only 35%, despite mean 1.3 ± 0.9 cm gain in stretched penile length.1 Other series promise significantly more.5

Despite claims that SL has no role in erection stability, it appears particularly susceptible to injury during rough intercourse. Main complaints after injury are altered erection angle, marked instability, pain, and rotational deformity (if unilateral). De novo venogenic ED has also been reported following such sexual trauma, as indicated by penile Doppler and cavernosometry, and resolved following PSL repair. Given that the SL envelops the deep dorsal vein, a veno-occlusive mechanism is not inconceivable when the vein is compressed between the erect corpora and the PS.7

Congenital PSL deficiency is another distinct pathology; however, ED and other causes of downward curvature must be first excluded. These men have an altered angle of erection and often present with inability to maintain sexual intercourse due to slippage of the erect penis. Repair in such cases, via proximal corporopexy to the pubic periosteum, has been shown to resolve the sexual dysfunction associated with erection instability. The mean improvement in erection angle of 80° was associated with an average penile shortening of 1 cm.8 As such, it remains unclear how a published series of 260 PESs produced a mean length gain of 4 cm, without decreased erection angle.9

Interrogation of the PSL anatomy is paramount to resolve these discrepancies, ensure patients are appropriately informed, and strive for the best possible outcomes in urological reconstruction. A novel technology that combines epoxy-sheet plastination with confocal-laser microscopy was used to bridge this apparent disconnect.10 This technique is superior to traditional dissection techniques, in which macroscopic anatomy is distorted, and histological examination, which only permits analysis of isolated sections with a small field of view. Plastination allows preservation of in situ architecture and endogenous autofluorescence of collagen/elastin/myofilaments when excited using 488-nm confocal-laser microscope. Thus, connective tissue can be traced across broad anatomical areas using montaged slices (Figure 1). Data obtained from 6 male cadavers were used in the present study.

Based on this new insight, we propose a new classification system for the PSL that corresponds to distinct histoarchitectural origins of its different components: prepubic, subpubic, and retropubic (Table, Figure 2). Fibers in the prepubic region all have a musculotendinous origin from the abdominal wall musculature and its investing fascia. This same origin also contributes to Scarpa’s fascia, hence the confusion even in most reputable textbooks (Figure 3). The subpubic component was made up of only ligamentous fibers (from bone or cartilage) and inserted directly into the TA. Interestingly, a nondominant portion of these fibers ran perpendicular to the others. To our knowledge, this is the first description of decussating SL fibers, although connective tissue decussation can be observed elsewhere in the body where stability is a priority. These findings demonstrate that the subpubic ligaments, divided in PES, are the main penile support structure (Figure 4). Contrary to popular belief, the professed AL not only has no role in penile support, but does not appear to be anatomically related to the corpora at all. In another first, fibers of the retropubic PSL have been described. These were all musculotendinous in origin and extended anteriorly from the investing fascia of the urogenital diaphragm. They insert into and likely contribute to the TA (Figure 5).

The anatomical rationale of current PES techniques, promising a slightly longer penis without functional compromise, appears unfounded. The biomechanical outcome of subpubic ligament division is not dissimilar to an anterior cruciate ligament injury of the knee. Further studies are required to validate this classification, but use of this technology will undoubtedly lead to new anatomical insights. These will be invaluable to advancement of urological reconstructive surgery and will hopefully ensure optimal use of length-preservation techniques in appropriately counseled patients.

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