Pelvic Girdle Pain: Causes, Symptoms, and Risk Factors

Why do you get pelvic girdle pain?

Pelvic girdle pain (PGP) arises from dysfunction or instability within the joints, ligaments, and muscles that comprise and support the pelvic ring, leading to pain in the lower back, buttocks, groin, or thighs due to altered load transfer and biomechanical stress.

Understanding the Pelvic Girdle

The pelvic girdle is a robust ring of bones at the base of the spine, crucial for weight bearing, locomotion, and organ protection. It consists of:

• Two Innominate Bones: Each formed by the fusion of the ilium, ischium, and pubis.
• The Sacrum: A triangular bone at the base of the spine, wedged between the two innominate bones.
• The Coccyx: The tailbone, inferior to the sacrum.

The primary joints involved in PGP are:

• Sacroiliac Joints (SIJs): Formed where the sacrum meets the ilia on either side. These joints are designed for stability, with minimal movement, and are reinforced by strong ligaments.
• Pubic Symphysis: A cartilaginous joint connecting the two pubic bones at the front of the pelvis. This joint also allows for very limited movement.

The stability of the pelvic girdle relies on a complex interplay of form closure (the anatomical fit of the bones and joints) and force closure (the tension provided by surrounding ligaments and muscles, including the deep core musculature like the transversus abdominis, multifidus, pelvic floor, and diaphragm, as well as global movers like the glutes and adductors). Disruptions to this delicate balance are primary drivers of PGP.

Primary Causes of Pelvic Girdle Pain (PGP)

PGP is a multifactorial condition, often stemming from a combination of mechanical, hormonal, and inflammatory factors.

• Pregnancy-Related Pelvic Girdle Pain (PPGP): This is the most common cause of PGP.
  • Hormonal Changes: Elevated levels of hormones like relaxin and progesterone increase ligamentous laxity throughout the body, including the pelvic joints, making them more susceptible to excessive movement.
  • Biomechanical Stress: The growing fetus and uterus alter the center of gravity, increasing lumbar lordosis and anterior pelvic tilt. This shifts load distribution, placing greater stress on the SIJs and pubic symphysis.
  • Postural Adaptations: Changes in gait and posture to accommodate the growing belly can lead to muscle imbalances and altered movement patterns.
• Trauma:
  • Direct Impact: Falls onto the buttocks, car accidents, or direct blows to the pelvis can injure the joints, ligaments, or surrounding soft tissues.
  • Repetitive Microtrauma: Activities involving repetitive asymmetrical loading (e.g., running, jumping, twisting) can lead to cumulative stress on the pelvic joints.
• Biomechanical Dysfunction and Muscle Imbalances:
  • Asymmetrical Loading: Activities or postures that consistently load one side of the pelvis more than the other (e.g., standing with weight on one leg, carrying heavy loads on one side).
  • Muscle Weakness/Inhibition: Weakness in key stabilizing muscles such as the gluteal muscles (gluteus medius, gluteus maximus), deep core muscles (transversus abdominis, multifidus), or hip abductors can compromise force closure.
  • Muscle Overactivity/Tightness: Overly tight or hypertonic muscles (e.g., hip flexors, adductors, piriformis) can pull the pelvis out of alignment or restrict normal joint movement, creating compensatory stress elsewhere.
  • Hypermobility: Some individuals naturally have more flexible joints, which can lead to excessive movement at the SIJs or pubic symphysis, requiring greater muscular stabilization.
  • Hypomobility: Conversely, restricted movement in one part of the pelvic girdle can force compensatory excessive movement in another, leading to pain.
  • Gait Abnormalities: Leg length discrepancies, foot pronation, or other lower limb biomechanical issues can alter pelvic mechanics and contribute to PGP.
• Degenerative Conditions:
  • Osteoarthritis: Wear and tear of the articular cartilage in the SIJs can lead to pain, stiffness, and inflammation, particularly in older adults.
• Inflammatory Conditions:
  • Spondyloarthropathies: Systemic inflammatory diseases like ankylosing spondylitis or psoriatic arthritis can cause inflammation and pain in the SIJs (sacroiliitis).
• Post-Surgical Complications:
  • Pelvic or spinal surgeries can sometimes lead to altered biomechanics, scar tissue formation, or nerve irritation contributing to PGP.
• Nerve Entrapment:
  • Compression or irritation of nerves in the pelvic region (e.g., pudendal nerve, cluneal nerves, sciatic nerve) can mimic or contribute to PGP symptoms.

Risk Factors for Developing PGP

Several factors can increase an individual's susceptibility to PGP:

• History of Previous Back or Pelvic Pain: Prior episodes suggest underlying vulnerabilities.
• High-Impact Sports or Activities: Sports involving repetitive jumping, running, or asymmetrical movements.
• Occupational Demands: Jobs requiring prolonged sitting, standing, repetitive lifting, or twisting.
• Generalized Joint Hypermobility: Individuals with naturally "loose" joints may be more prone to PGP.
• Obesity: Increased body weight places greater load on the pelvic joints.
• Stress and Psychological Factors: Chronic stress can increase muscle tension and alter pain perception, exacerbating PGP.

Common Symptoms of PGP

PGP typically manifests as pain in one or more of the following areas:

• Lower Back: Often unilateral, near the dimples of Venus (over the SIJs).
• Buttocks: Deep pain, sometimes radiating down the back of the thigh.
• Groin: Pain in the front of the pelvis, near the pubic bone, often radiating down the inner thigh.
• Perineum: Pain in the area between the genitals and anus.
• Inner Thigh: Referred pain from the pubic symphysis or adductor muscles.

The pain can be described as sharp, stabbing, dull, aching, or a feeling of instability. Activities that commonly aggravate PGP include:

• Walking, especially long distances.
• Standing for prolonged periods.
• Climbing stairs.
• Turning in bed or rolling over.
• Single-leg stance (e.g., putting on pants).
• Getting in and out of a car.
• Asymmetrical movements like lunging or crossing legs.
• Weight-bearing on the affected side.

The Biomechanical Perspective: Why Pain Occurs

From a biomechanical standpoint, PGP occurs when the normal load transfer mechanisms across the pelvic ring are compromised.

• Disrupted Form and Force Closure: When the passive (ligaments) and active (muscles) stabilizers of the pelvic girdle fail to adequately stabilize the joints during movement, excessive micro-movements or shearing forces can occur. This irritates joint capsules, ligaments, and surrounding nerves, leading to pain.
• Ligamentous Laxity: Whether due to hormones (pregnancy), trauma, or genetics, lax ligaments mean the joints rely more heavily on muscular control. If these muscles are weak or dysfunctional, instability and pain ensue.
• Muscle Imbalance and Compensation: Weak core stabilizers, glutes, or hip abductors can lead to over-reliance on other muscles (e.g., hip flexors, adductors, hamstrings) that are not designed for primary pelvic stabilization. This compensatory overuse can lead to muscle pain, trigger points, and further perpetuate dysfunctional movement patterns.
• Altered Neuromuscular Control: The brain's ability to coordinate muscle activity around the pelvis can be impaired by pain or injury, leading to inefficient movement and continued stress on the joints.

When to Seek Professional Guidance

While many cases of PGP can be managed with conservative measures, it is crucial to consult a healthcare professional (e.g., physical therapist, orthopedist, chiropractor) if you experience:

• Persistent or worsening pelvic girdle pain.
• Pain that significantly interferes with daily activities or sleep.
• Associated neurological symptoms such as numbness, tingling, or weakness in the legs.
• Pain following a significant trauma.

An accurate diagnosis is essential to rule out other conditions and to develop an effective, individualized treatment plan that addresses the root cause of your pelvic girdle pain.