1. Introduction
Stress urinary incontinence (SUI) is a common problem that affects about
a third of adult women, with onset at an average age of 45 years (1). It
is defined as involuntary loss of urine with increasing intra-abdominal
pressure as may occur during coughing, sneezing and physical activity
(2), and is a cause of significant medical, social, and economic burdens
(3-6). Risk factors for the development of SUI are well known and
include age, genetic predisposition, menopause, obesity, and diabetes
mellitus (7). Pelvic floor muscle dysfunction is strongly associated
with the development of SUI, as it contributes to bladder prolapse,
hypermobility of the bladder neck and impaired function of the urethral
sphincter (2).
Treatment modalities for SUI include physical therapy, vaginal
incontinence pessary, urethral bulking agent injections, and surgical
repair (4). The cumulative incidence, or lifetime risk, of surgery for
SUI is 13.6% (8). Midurethral sling placement (MUS) is considered the
gold standard surgical solution for SUI, during which a polypropylene
sling is inserted under the mid-urethra. The main routes for sling
placement are the retropubic approach (sling curves around the pubic
bone and exits through two suprapubic incisions) and transobturator
approach (TOT) where the sling is directed through the obturator foramen
to the inguinal folds (3).
MUS success rates are high (9), yet they carry risk for complications
including pelvic organ injury and postoperative pain. The retropubic
approach is more commonly linked to bladder perforation, injury to the
intestines and large blood vessels. Complications of the transobturator
approach on the other hand, include vaginal wall perforation,
postoperative moving disability, and groin pain.
There is a paucity of evidence regarding the association between MUS and
lower extremity dysfunction (10). Important anatomical structures in the
vicinity of the sling route that could potentially be injured during
surgery include: the deep external vascular bundle that is located near
the groin; the deep femoral artery that crosses the obturator foramen;
the obturator nerve with its two divisions (anterior and posterior) that
exit the pelvis through the obturator canal; and the obturator-accessory
nerve (11). Adequate function of hip muscles is beneficial in
maintaining urinary continence. Hip replacement surgeries for patients
with osteoarthritis for example, have been shown to alleviate
incontinence symptoms, owing to their thigh muscles strengthening effect
(12). This could be due to the anatomical relation between the obturator
internus muscle and the levator ani muscle, the latter responsible for
maintaining proper position of the bladder neck (13).
Based on the increasing prevalence of SUI surgeries, the potential for
intraoperative injury to surrounding neuromuscular structures, and the
importance of the hip musculature for daily functioning, we have sought
to further evaluate the association between TOT procedures and various
indices of hip joint pain and function.