Editing Penis and Urethra Surgery (section)

== Principles of Reconstructive Surgery ==

=== Graft vs. Flap ===
* '''Tissues can be transferred as a graft or flap'''
* '''<span style="color:#ff0000">The term flap implies that the tissue is excised and transferred WITH THE BLOOD SUPPLY either preserved or surgically re-established at the recipient site'''
** Important considerations for the use of flaps in urethral reconstruction:
**# Nature of the flap tissue
**# Vasculature of the flap
**# Mechanics of flap transfer
* '''<span style="color:#ff0000">The term graft implies that tissue is excised and transferred to a graft host bed, where a NEW BLOOD SUPPLY develops by a process termed take'''
** '''Take requires ≈96 hours and occurs in 2 phases:'''
**# '''Initial phase: imbibition'''
**#* '''Requires ≈48 hours'''
**#* '''Graft survives by “drinking” nutrients from the adjacent graft host bed'''
**#* '''Temperature of the graft is less than the core body temperature'''
**# '''Second phase: inosculation'''
**#* '''Requires ≈48 hours'''
**#* '''True microcirculation is reestablished in the graft'''
**#* '''Temperature of the graft increases to core body temperature'''

=== Tissue Grafts ===
==== Graft Anatomy ====

* [[File:Skin layers.png|alt=Anatomy of Skin Layers|thumb|600x600px|Anatomy of Skin Layers. Source: [[commons:File:Skin_layers.png|Wikipedia]]]]'''Superficial to deep:'''
# '''Epidermal, or epithelial layer'''
#* Acts as the barrier to the “outside”
# '''Superficial dermis, or superficial lamina or papillary dermis'''
#* '''On the undersurface of the superficial dermis is the superficial plexus.'''[https://journals.lww.com/jdnaonline/Fulltext/2011/07000/Anatomy_and_Physiology_of_the_Skin.3.aspx §][https://www.histology.leeds.ac.uk/skin/skin_layers.php §]
#** '''In the case of skin, the superficial plexus''' '''is called the intradermal plexus'''
#** Campbell's suggests that the intradermal plexus is between the epidermis and superficial dermis
#* '''Contains some lymphatics'''
# '''Deep dermis, or deep lamina or reticular dermis'''
#* '''On the undersurface of the deep dermal layer''' '''or deep lamina is the deep plexus.'''
#** '''In the case of skin, this deep plexus''' '''is called the subdermal plexus'''
#* '''Contains most of the lymphatics'''
#* '''Greater collagen content than found in the superficial dermal layer'''
#* '''Generally thought to account for the physical characteristics of the tissue'''

==== Classification ====
*'''Split-thickness vs. full-thickness'''

===== Split-thickness graft =====
* '''Carries the epidermis (or the covering) and variable amount of [superficial] dermis'''
** '''Reticular dermis is not carried with the split-thickness skin graft'''
** '''Exposes the superficial dermal (intradermal or intralaminar) plexus'''
* '''Advantage:'''
** '''Favorable vascular characteristics'''
* '''Disadvantage:'''
** '''Tends to contract and be brittle when mature'''
* '''A mesh graft is usually an application of the split-thickness graft.'''
** '''After the harvest of a sheet graft, the sheet is placed on a carrier that cuts systematically placed slits in the graft.''' These slits can expand the graft by various ratios'''.'''
*** For most genital reconstructive surgery, the slits are not for expansion but rather to allow subgraft collections to escape and allow the graft to conform better to irregular graft host beds (e.g., the testes in split-thickness skin graft scrotal construction).

===== Full-thickness graft =====
* '''Carries the epidermis (or the covering) and all of the dermis (the superficial dermis (or lamina) and the deep/reticular dermis (or deep lamina))'''.
** '''Exposes the subdermal plexus''' in skin.
** A full-thickness unit carries most of the lymphatics, and the physical characteristics are likewise carried with the transferred tissue
* '''Advantage:'''
** '''Does not contract as much and is more durable when mature'''
* '''Disadvantage:'''
** '''More fastidious vascular characteristics'''
==== Grafts in Urology ====

===== Primary urethral reconstruction (5) =====
# '''<span style="color:#ff0000">Oral mucosal graft'''
#* '''<span style="color:#ff0000">Can be taken from (3):'''
#*#'''<span style="color:#ff0000">Cheek (buccal)'''
#*#'''<span style="color:#ff0000">Lip (labial)'''
#*#'''<span style="color:#ff0000">Undersurface of the tongue (lingual)'''
#* '''Buccal mucosa is thought to have a panlaminar plexus'''
#'''<span style="color:#ff0000">Bladder epithelial graft'''
#* Issues with desiccation and hypertrophic growth have limited its use in the distal urethra
#'''<span style="color:#ff0000">Rectal mucosa graft'''
#* Little is known about the characteristics of the rectal mucosal graft
#'''<span style="color:#ff0000">Skin grafts (full-thickness (FTSG) and split-thickness (STSG))'''
#* STSGs have been used for staged anterior urethral reconstruction
#* Extragenital FTSGs have an increased mass compared to genital FTSGs.
#** This increased mass makes the graft more fastidious, and the poor results reported with urethral reconstruction with extragenital FTSGs are probably due to poor or ischemic take.
#** The posterior auricular graft (Wolfe graft) is an exception to the rule concerning extragenital skin.
# '''<span style="color:#ff0000">Skin island flaps based on the dartos fascia or tunica dartos'''
* The bladder epithelial graft and the oral mucosal graft have numerous vascular properties that make them desirable for urethral reconstruction.
* '''Tunica vaginalis grafts have been tried for urethral reconstruction with uniformly poor results.'''

===== Penile reconstruction =====
* '''<span style="color:#ff0000">Split-thickness skin grafts (preferred) and full-thickness skin grafts and have been used for penile reconstruction.'''
** '''The highest probability of 100% graft take and best cosmetic results occur with penile skin reconstruction using an unmeshed thick''' (0.012 - 0.015 inch) '''STSG'''.
*** Meshed or thinner STSGs have more of a tendency to contract which compromises penile functionality and cosmesis.
*** FTSGs may provide adequate cosmesis but are associated with a higher incidence of failure of the graft to take.
**** The results with STSGs are so good that FTFGs are rarely used for coverage of the penis.
*** Local skin flaps from the abdomen or thigh generally do not produce the same cosmetic outcomes.
* '''Tunica vaginalis grafts have proved useful for small defects of the tunica albuginea of the corpora cavernosa.'''

==== Generalities of reconstructive surgical techniques ====
* Reconstructive surgery is performed with all efforts aimed at minimizing tissue injury and promoting healing.
* Bipolar surgery is often preferred.
** With cautery, the electrical charge is grounded either to a pad (monopolar) or to the opposite tong of the forceps (bipolar).
** Because electricity is dissipated by conductors (in the case of human tissue, vessels, and nerves), there is a possibility of damage to these delicate structures.
** In most instances, the field effects of the electricity are more confined with bipolar cautery.
* In urethral surgery, absorbable suture is the rule. The needle should be tapered if possible
* '''Femoral neuropathy can occur after lithotomy procedures due to hip hyperabduction/hyperextension, or secondary to retractor injury with abdominal/pelvic procedures.'''
** '''Femoral nerve'''
***Largest branch of the lumbar plexus
***Formed within the psoas muscle from the fusion of the anterior divisions of L2-L4
***Emerges between the psoas major and iliacus muscles just superior to the inguinal ligament and enters the thigh lateral to the external iliac artery
*** '''Sensory branches are the anterior and medial femoral cutaneous and long saphenous nerves.'''
**** '''Responsible for sensation of anterior thigh and medial leg'''
*** '''Motor supply is to the psoas, iliacus, quadriceps, pectineus, and sartorius muscles.'''
**** '''Responsible for knee extension'''