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What is Psoas Avulsion Injuries?

The psoas is a long muscle located in the lower back area of the spine and extends through the pelvis to the femur or thigh bone. This muscle helps to flex your hips, bend your trunk towards your thighs, rotate your femur, and enable additional movements of the lumbar spine. The psoas and iliacus muscles join together to constitute one single tendon known as the iliopsoas. Individually, these muscles are commonly referred to as "hip flexors."

Avulsion injuries or fractures occur where the joint capsule, ligament, tendon, or muscle attachment site is pulled off from the bone, typically taking a piece of cortical bone. The psoas muscle can become injured from overuse, muscle tightness, muscle weakness, or trauma, resulting in avulsion (tearing away) from its bony attachment. The injuries can occur anywhere along with the psoas muscles, including the portion of the hip referred to as the lesser trochanter - the bony projection from the lower or back part of the femur neck base.

Picture of Psoas Avulsion Injuries

While rare, isolated avulsion injuries of the lesser trochanter occur in children and adolescents before the fusion of this apophysis due to athletic activities. In the elderly, isolated avulsion injuries of the lesser trochanter are uncommon but can occur due to trauma.

A psoas avulsion injury of the lesser trochanter can be classified based on its location and degree of displacement.

  • Type I occurs at the level of the lesser trochanter
  • Type II occurs within 2.5 cm below the lesser trochanter
  • Type III occurs between 2.5 and 5 cm below the lesser trochanter

Causes of Psoas Avulsion Injuries

Although psoas avulsion injuries can affect people of all ages, it is most often noted in athletes participating in sports. The common causes of psoas avulsion injuries include an acute or overuse injury from repeated bending of an externally rotated hip. It is specifically common in ballet dancers with more than 90 percent reporting a snapping or clicking sensation. The condition may also occur due to activities such as resistance training, gymnastics, soccer, rowing, track and field, and uphill running. Other causes of psoas avulsion injuries include:

  • Activities or sports that involve speed and sudden stops
  • Sudden and/or forceful contraction of the pelvic muscle
  • A motor vehicle accident or any accident that puts sudden stress on the hip

Signs and Symptoms of Psoas Avulsion Injuries

The common signs and symptoms of psoas avulsion injuries include:

  • Pain in the groin, pelvis, buttocks, and hips
  • Pain in the lower back/lumbosacral region
  • Audible snap or click in the hip or groin
  • Pain that radiates down to the knee
  • Shuffling or limping gait while walking
  • Pain with hip flexion, extension, rotation, abduction, and adduction

Diagnosis of Psoas Avulsion Injuries

Psoas avulsion injuries are diagnosed through a review of your medical history and a detailed physical examination of your spine, pelvis, hip, and leg. Your doctor will also perform the following:

  • Inspection of the hip at rest and with flexion
  • Palpation of the hip joint to assess for any swelling or unusual tenderness
  • Imaging tests such as x-rays, ultrasound, and MRI scans of the hip and pelvis to confirm the diagnosis

Treatment for Psoas Avulsion Injuries

Psoas avulsion injuries can be treated both conservatively and surgically depending upon the severity of the injury. The conventional treatments of psoas avulsion injuries include but are not limited to:

  • Activity modification and rest
  • Ice therapy where ice packs can be applied to the site of injury intermittently during the first few days.
  • A period of non-weight bearing, followed by protected weight-bearing after a week with the use of crutches or a walker
  • Non-steroidal anti-inflammatory drugs (NSAIDs) for pain and inflammation
  • Physical therapy and stretching exercises to improve muscle strength, restore range of motion, and promote healing

Most psoas avulsion injuries are known to heal well without surgical intervention. However, you might require surgical intervention if conservative treatment has failed to resolve your symptoms or if you have injuries with either large fragments or more than 15 mm of displacement.