Groin pain can be caused by a variety of musculoskeletal pathologies occurring in and around the region of the pubic symphysis.
Assessment of groin pain can be challenging for a number of reasons:
Firstly,
the anatomy of the groin is complex due to the interconnected anatomy of the pubic symphysis and surrounding structures.
Secondly,
the differential diagnosis is wide and radiological assessment using ultrasound or MRI is usually required to reach a diagnosis.
Thirdly,
the pain is typically poorly localised making evaluation on clinical assessment difficult.
Knowledge and appreciation of the complex groin anatomy is required to understand the variety of pathologies arising in this region.
Key Anatomy of the Groin:
Pubic Symphysis: (Fig.
1)
The anatomy around the pubic symphysis is complex with a number of structures converging in this area to provide dynamic stability.
The pubic symphysis is a non-synovial joint and is designed to resist compressive and shearing forces.
It is composed of the pubic bones on either side which are lined with thin hyaline cartilage and articulating with a central fibrocartilaginous disc.
Further strengthening of the joint is provided by the superior,
inferior,
anterior and posterior pubic ligaments that surround the joint.
The inferior public ligament is also known as the arcuate ligament and is an important stabiliser.
This blends with the underlying fibrocartilaginous disc and overlying aponeurosis (formed by the adductors-rectus abdominis) and provides further joint reinforcement.
Adductor musculature: (Fig.
2/3/4)
The adductor muscles (adductor longus,
brevis,
magnus,
pectineus and gracillis) are located in the medial aspect of the thigh with their tendinous origin arising from the anterior pubic bone.
The adductor longus lies anterior to the other adductor tendons and is an important structure to analyse when assessing a patient with groin pain.
Abdominal wall musculature:
The abdominal wall musculature includes the rectus abdominis muscle anteriorly and the transversus abdominis,
internal and external oblique muscle anterolaterally.
These muscles attach around the pubic symphysis.
The rectus abdominis muscle is enclosed by the rectus sheath.
The fascia surrounding the three anterolateral muscles fuse anteriorly to attach to the rectus abdominis muscle at the linea semilunaris.
Common Adductor : Rectus Abdominis Aponeurosis: (Fig.
5/6)
The most important stabilisers of the anterior pelvis are the rectus abdominis and adductor longus muscles.
The fibres of the rectus abdominis muscle and adductor longus origins merge together anterior to the pubic body and form an aponeurosis at the level of the pubic symphysis.
This attaches to the periosteum of the anterior pubic bones and blends with the anterior pubic ligament.
This ligament blends with the interpubic fibrocartilaginous disc & helps to stabilise the anterior pelvis.
Inguinal canal & inguinal ligament: (Fig 7)
The inguinal canal is an oblique tunnel in the anterior abdominal wall which allows transit of structures from the pelvis to the perineum.
It measures approximately 4cm in length and runs along the course of the medial aspect of the inguinal ligament which extends from the anterior superior iliac spine to the pubic tubercle.
The inguinal canal boundaries are: the floor formed by the inguinal ligament,
the anterior wall formed by the external and internal oblique aponeuroses,
the posterior wall by the transversalis fascia and conjoint tendon and the roof by the internal oblique and transversus abdominis muscles.
The inguinal canal has two openings – the deep and superficial inguinal rings.
The deep ring opens in the transversalis fascia,
1cm lateral to the inferior epigastric arteries and the superficial ring opens medially in the external oblique aponeurosis,
superolateral to the pubic tubercle.