The pubic symphysis forms where the bodies of the two pubic bones meet anteriorly, connected by the interpubic disc, and is bounded superiorly by the superior pubic ligament and inferiorly by the inferior pubic ligament. When the pubic bones come together anteriorly, they contribute to stabilizing the pelvic girdle and transferring weight from the upper to the lower body, while childbirth involves important changes that allow passage of the fetus through the birth canal.
What conditions affect the pubic symphysis?
Symphysis pubis dysfunction (SPD) is an umbrella term for symptoms you feel because of changes in your pubic symphysis. Two types include: Pubic diastasis: The joint separates more than 1 centimeter without a pubic fracture. Osteitis pubis: This is inflammation of the joint that isn’t caused by an infection. Pregnancy is a common cause of SPD. During pregnancy, a hormone called relaxin loosens the ligaments that hold your pubic symphysis in place. This can cause issues. Sports injuries are another common cause, especially when you make quick, sharp changes in movement.
Bone and joint conditions that can affect your pubic symphysis include: Degenerative diseases, like osteoarthritis; Fractures; Metabolic bone diseases, like osteoporosis and renal osteodystrophy; Pseudogout; Rheumatoid arthritis; Tumors or cancer. Signs that something’s wrong include pain and instability in the pelvis, with possible sharp pain in the pelvis or groin, and sometimes pain spreading to the abdomen, hips and back.
Having trouble with certain movements can cue that something’s wrong. You may feel: Less flexibility in your groin; A grinding feeling when you move your pelvis; Pain or a clicking sound when you’re walking; Aching in your groin when you try to run, kick, stand or sit; Pain when you twist your body or maneuver to reach something. Your healthcare provider can check if a problem with your pubic symphysis is causing your symptoms.
Anatomy and relationships of the pelvic bones
The pelvic girdle is a basin-shaped ring that connects the axial skeleton to the lower limbs, transfers weight, and provides attachment points for muscles involved in locomotion and posture. The pelvis consists of the right and left hip bones, each formed by the fusion of the ileum, ischium, and pubis, and the sacrum posteriorly. The pubic symphysis is the anterior joint joining the two pubic bodies, with the interpubic disc providing fibrocartilaginous linkage.
The hip bones comprise three elements: the ileum, ischium, and pubis. The ileum contributes the iliac crest and anterior superior iliac spine; the ischium provides the ischial tuberosity and ischial spine; and the pubis forms the pubic body and rami that converge to create the pubic arch and the obturator foramen. The acetabulum is formed by contributions from the ilium, ischium, and pubis, where the femoral head articulates.
Posteriorly, the ilia articulate with the sacrum at the sacroiliac joints, reinforced by ligaments such as the anterior and posterior sacroiliac ligaments and the interosseous sacroiliac ligament. The sacrum connects superiorly to L5 and anteriorly to the coccyx via the sacrococcygeal joint. Ligaments including the sacrospinous and sacrotuberous ligaments help convert the greater and lesser sciatic notches into foramina, through which nerves and vessels pass.
Clinical features and evaluation
SPD and pubic symphysis disorders present with pelvic pain and instability, with symptoms that may be influenced by pregnancy, physical activity, or underlying bone or joint diseases. Diagnosis is typically clinical, supported by history of pain with movement and stability changes, and may be confirmed with imaging or targeted physical examination as needed by a clinician.
Fractures or severe trauma can involve the pelvis and may require urgent stabilization. Pelvic fractures are potentially life-threatening due to possible internal bleeding; management includes rapid fluid resuscitation and stabilization, with consideration of surgical fixation depending on the fracture pattern and associated injuries. Surgical approaches include anterior or posterior fixation, with techniques such as INFIX for anterior fixation or posterior percutaneous sacroiliac fixation when appropriate, taking care to avoid nearby neurovascular structures.
Pelvis in life: function, birth, and variation
The pelvis serves locomotion, childbirth, and protection of abdominal viscera. During childbirth, pubic symphysis relaxation increases the subpubic angle and allows passage of the fetus through the birth canal. There are notable physiologic variants between male and female pelves: males tend to have thicker, heavier pelves with a heart-shaped inlet and a smaller subpubic angle; females typically have a wider, oval pelvic inlet and larger subpubic angle to accommodate childbirth.
Pelvic dimensions are important in obstetrics and surgery. Radiographic or pelvic examination assessments estimate the pelvic inlet and the space available for vaginal delivery. The diagonal conjugate is used in exams, and the distance between the ischial spines helps gauge the narrowest point of the canal. When anatomical conditions restrict vaginal delivery, cesarean section may be considered. Post-traumatic management may involve reduction and fixation of pelvic fractures using varied approaches depending on the trauma and injuries.
Summary of relationships and structures
The pubic symphysis links the pubic bones at the midline, supported by ligaments and cartilage, forming part of the pelvic ring along with the sacroiliac joints and the acetabulum. The pelvis transfers weight from the axial skeleton to the lower limbs and houses essential reproductive, urinary, and digestive structures, with multiple muscles, nerves, and vessels attaching to and traversing its surfaces.
Pelvis Hip Bones Anatomy (Os Coxae, Pelvic Girdle) - Ilium, Ischium, Pubis
In clinical practice, understanding the pubic symphysis and pelvic architecture aids in diagnosing SPD and other pelvic conditions, planning obstetric or surgical interventions, and anticipating how changes in the pelvis affect movement and stability.