The pubic symphysis is the joint where the left and right halves of your pelvis meet at the front. It sits just above your genitals and below your belly button, and you can often feel it as a firm ridge beneath the skin. Unlike most joints in the body, it barely moves. Its job is to hold the two sides of the pelvis together while absorbing the forces generated by walking, running, and standing on one leg.
How the Joint Is Built
The pubic symphysis is classified as a cartilaginous joint, meaning it’s held together by cartilage rather than a fluid-filled capsule like your knee or shoulder. At its center is a thick disc of fibrocartilage, a dense, fibrous material made mostly of type I collagen. This disc acts as both a connector and a shock absorber between the two pubic bones.
Four ligaments reinforce the joint from every direction: one on top (superior), one on the bottom (inferior), one in front (anterior), and one in back (posterior). Together, these ligaments keep the fibrocartilage disc from slipping or allowing the two halves of the pelvis to shift apart. The result is a joint that permits only a few millimeters of movement, just enough to flex slightly under stress without breaking.
What It Does in the Body
Every time you take a step, the pubic symphysis helps distribute the load across your pelvis. When you stand on one leg, for example, stress concentrates along the front of the pelvis near the symphysis and along the sacroiliac joints at the back. The stiffness of the pubic symphysis determines how that load is shared between the front and back of the pelvic ring. If the symphysis softens, more force shifts to the back of the pelvis. If it stiffens, more force moves forward.
This balancing act matters because it protects individual bones and joints from bearing too much stress on their own. The symphysis essentially acts as a structural keystone for the pelvic ring, keeping forces evenly distributed during everyday activities like walking, climbing stairs, and bending.
Normal Width and When It’s Too Wide
In a healthy, non-pregnant adult, the pubic symphysis gap measures roughly 3 to 5 millimeters at its narrowest point. Imaging studies show that the midpoint width averages about 4.7 mm, with only slight differences between men and women. Women who have given birth tend to have a somewhat wider gap, with older cadaver studies estimating around 7.5 mm in women who haven’t delivered and up to 20 mm in women who have delivered multiple times.
A gap wider than 10 mm combined with symptoms like pain or difficulty walking is generally considered pathological. On X-rays, any separation exceeding 1 cm points to a disruption of the joint. If the gap reaches 4 cm or more, imaging of the surrounding soft tissues is typically needed to check for ligament and cartilage damage.
Changes During Pregnancy
The pubic symphysis undergoes significant changes during pregnancy, largely driven by the hormone relaxin. Relaxin loosens the ligaments throughout the pelvis to make room for the baby during delivery. Its levels peak during the first trimester and again near the time of birth, and it directly softens the fibrocartilage disc and the four supporting ligaments of the symphysis.
For most pregnant women, this loosening causes a mild, painless widening of the joint. But in some cases, the symphysis separates more than it should, a condition called pubic symphysis diastasis. This is diagnosed when the gap exceeds 10 mm and is accompanied by pain in the front of the pelvis, difficulty walking, or a feeling of instability. Pain often worsens with activities like rolling over in bed, standing on one leg, or climbing stairs.
Managing Pelvic Pain During Pregnancy
When the symphysis becomes painful during pregnancy, treatment focuses on reducing stress across the joint while waiting for delivery. Pelvic support belts that wrap around the hips can help stabilize the pelvis, and several small clinical trials have shown they reduce pain in the symphysis and sacroiliac regions. Physical therapy focused on core and pelvic stability exercises can also help, though programs should be tailored to the individual since evidence for a one-size-fits-all approach is limited.
For pain relief, acetaminophen is considered safe during pregnancy. Anti-inflammatory medications like ibuprofen should be avoided during pregnancy because of risks to fetal development, but they can be used after delivery. In more severe cases, image-guided injections of a local anesthetic and corticosteroid into the joint may be effective. Current evidence suggests these localized injections don’t pose significant risks to the mother or baby.
Most pregnancy-related symphysis pain resolves after delivery, though recovery can take weeks to months depending on severity.
Symphysis Pubis Dysfunction (SPD)
Symphysis pubis dysfunction is a broader term for pain and instability centered at the pubic symphysis, most commonly during or after pregnancy. The hallmark symptom is tenderness directly over the front of the pelvis, but the pain often radiates to the inner thighs, lower back, and buttocks. Walking may become a wide, shuffling gait with short steps. Getting out of a car, turning over in bed, or standing on one leg can all trigger sharp pain.
Clinicians check for SPD by pressing on the symphysis, testing whether the pelvis stays level when you stand on one leg (a positive Trendelenburg sign suggests it doesn’t), and using specific leg movement tests. One self-screening option is the MAT test: lying down and moving your legs apart and together as if pulling a mat between your knees. If this reproduces your pain, it correlates well with clinical findings and avoids the discomfort of direct palpation. Swelling above the pubic bone and a palpable gap in the joint are other telltale signs.
Overuse Injuries in Athletes
Outside of pregnancy, the pubic symphysis is most commonly injured through repetitive athletic stress, a condition historically called osteitis pubis. It’s an overuse syndrome driven by the opposing pull of the abdominal muscles and inner thigh (adductor) muscles, both of which attach to the pubic bones. Sports that involve kicking, pivoting, sprinting, and sudden direction changes put the most strain on the joint. Soccer, rugby, ice hockey, Australian rules football, and distance running are the usual culprits.
The mechanism is cumulative microtrauma. Each kick or twist applies a small amount of shearing force across the symphysis. Over time, this leads to inflammation of the joint and surrounding tissues, and eventually to instability. Reduced range of motion in the hips, particularly internal rotation, is a known risk factor because it forces the pelvic ring to absorb rotational stress that the hips would normally handle.
Treatment starts conservatively with rest and rehabilitation. The condition is self-limiting but slow to heal, sometimes lasting up to a year. Most athletes return to full activity within 4 to 13 weeks depending on severity, with averages around 9 to 10 weeks for moderate cases. Staged recovery timelines break down roughly to 3 weeks for mild cases, 7 weeks for moderate, and 10 weeks for more advanced inflammation. When conservative treatment fails, procedures like joint debridement can get athletes back to competition in about 3 to 6 months.