Introduction

Athletes who perform repetitive hip movements may experience consequential groin pain. It can be debilitating and negatively impact their performance. Whilst groin pain may go away with some rest and an ice pack, there are more serious sports-related injuries that can invoke long-lasting groin pain and require medical attention. A common cause of groin pain in athletes is psoas syndrome.

The psoae are twin muscles that play a huge part in hip movement and posture. They connect the lower spine to the thigh bones. Psoas syndrome is a condition in which an individual injures one or both of their psoae and experiences back, hip or groin pain. It tends to affect athletes, but it can also affect arthritis sufferers and those with a hip replacement. The pain can occur when changing positions, like sitting, or when stationary, like standing up straight.

The Psoas muscles

The two psoas (pronounced so-ezz) muscles are in the lower back and hips, one on each side of the spine. They connect the upper body to the lower body. The psoas muscle starts at attachments to the spine, close to the skin surface, then stretches through the pelvis and connects to the hip joints, where it is joined to the iliacus muscle. The other end of the iliacus muscle is attached along the top of the pelvis. Together, the psoas muscle and the iliacus muscle form the iliopsoas muscle, which is why you may hear psoas syndrome used interchangeably with iliopsoas syndrome.

The function of the iliopsoas muscles is to stabilize the lumbar spine in the sitting position and flex the thigh in the standing position. It flexes the hip, rotates the hip outwards, and moves the thigh away from the body.²

Causes

Psoas syndrome is an injury caused by overuse or trauma of the psoas muscles. The psoas muscle tendons become inflamed due to pressure or repetitive rubbing. It is a form of tendinitis, irritation of the tendons, which are the tissues that attach muscles to bones.²

This injury is seen in athletes who utilise their hips, like dancers, runners, high jumpers, and others who perform kicking motions.

It is more common in adolescents experiencing a growth spurt and AFAB individuals (assigned female at birth). A study performed on dancers shows that dancers under 18 were 1.8 times more likely to suffer from psoas syndrome, and AFAB dancers were 2.9 times more likely to suffer from psoas syndrome.³

Additionally, it is more likely to affect those suffering from inflammatory or degenerative arthritis in the hips.

Psoas syndrome can occur postoperatively in those with a hip replacement. The commonality of this is unclear. One study shows that 4.3% of patients experience psoas syndrome, while another shows that 24% of patients experience psoas syndrome.^4,5

Another cause may be an oversized acetabulum, a cavity in the pelvis in which the femur is connected (the hip joint).

Groin pain due to Psoas syndrome

Groin pain is common in athletes who perform kicking and pivoting motions. A study showed that up to 19% of all injuries in football clubs were groin injuries.¹ It is more common in male athletes, particularly young athletes as their pelvic joints are prone to damage.⁶

Groin pain can result from overuse injuries, including psoas syndrome, but also muscle strains, sprains (tearing of ligaments that connect two bones together), stress fractures, avulsion fractures, bursitis, as well as many others.

Psoas syndrome itself is rare, but it is one of the most prevalent causes of groin pain in athletes. A study found that among a group of athletes experiencing groin pain, 10% had tendon inflammation in the psoas.⁷

Due to the psoas muscles’ influence on the hip flexors, pain related to psoas syndrome in the groin occurs when the hip is stretched or flexed. When the knee is flexed at a right angle, there may be a feeling of ‘slipping’ or ‘catching’ in the groin.

Other Symptoms of Psoas Syndrome

Psoas syndrome causes pain in the groin, but also the hips and the back.

The psoas is the primary muscle in bringing the knee close to the chest. It attaches to the top of the thigh bone, and it is in this hip-joint area that there may be tenderness for an individual with psoas syndrome when it is pressed down on. There may also be a decreased range of motion in the extension of the leg and clicking of the hips accompanying the pain.⁶ Pain in the hips may result in the injured shuffling or limping.

When psoae tendons are inflamed, it can cause lower back pain. The back pain may travel up or down the spine, particularly between the bottom of the spine and the butt. It may also feel stiff. This pain can occur when changing positions, like sitting or standing. It can also be present when standing upright.⁸

All of these symptoms will most likely worsen with activity and improve with rest.⁸

Diagnosis

Because groin pain can be caused by many conditions, the diagnosis of psoas syndrome may involve a differential diagnosis, one in which other conditions are considered so they can be ruled out. Psoas syndrome is rare, so it may not be the first condition considered by the healthcare professional.

Red flags indicating the groin pain is more serious than psoas syndrome that the healthcare professional may look for is a history of cancer in reproductive organs or prostate cancer, as it may have spread to the groin region. Other red flags include weight loss, previous trauma to the region, fever, painful urination, and a history of prolonged corticosteroid use.⁶

An X-ray or a CT scan may be considered. These cannot diagnose psoas syndrome, but they would rule out other causes of groin pain, like fractures, urinary stones, and tumours.

Physical examination

A physical examination would consist of the healthcare professional asking about medical history, activities, and habits. They may need to press around the painful area to find any abnormalities and investigate the pain further. They may also require the patient to demonstrate their range of motion

A healthcare professional may attempt to find the exact region of pain. Some of the possible regions that relate to groin pain are:⁶

• The iliopsoas region
• The inner thigh (adductor)
• The pubic region
• The lower outer pelvis (inguinal)
• The hip region

Ultrasound scan

If a physical examination does not confirm the diagnosis, a healthcare professional may elect to use ultrasound imaging as it is harmless and returns real-time, dynamic imaging. Ultrasound can show a thickening of the iliopsoas tendon and an enlargement of a bursa. A bursa is the collection of lubricating fluid at a joint.

Lidocaine challenge test with ultrasound

A lidocaine challenge test is when lidocaine, a local anaesthetic, gets injected into the psoas tendon with an ultrasound scan used for assistance. If the pain is reduced when the psoas is numbed, this indicates the patient is suffering from psoas syndrome. The ultrasound is used to guide the healthcare professional to direct the needle towards the psoas muscle using a freehand technique.

MRI scan (Magnetic resonance imaging)

An MRI could be used to produce an image of joints, tissues and bones. It may allow the healthcare professional to diagnose if the patient has muscle strain in the psoas or tendinitis in the psoas. Recovering from tendinitis will take longer than recovering from muscle strain, hence why it is important to differentiate between the two, to prevent returning to athletics too early and causing further damage.⁷

Treatment

Physical therapy

Conservative management (avoiding surgery or other invasive procedures) is the primary treatment for psoas syndrome. It has proven to be an effective treatment strategy. A study was performed on dancers suffering from psoas syndrome in which they were prescribed physical therapy involving stretching of the hip flexor, modifying their dancing to reduce the leg extensions and rest. From this form of conservative management, 100% of the 49 participants had a positive response to the treatment.³

Another kind of physical therapy is a therapeutic ultrasound to heat soft tissues like muscles and tendons to increase circulation and reduce pain.

Exercise programs

A healthcare professional may prescribe exercises that stretch and strengthen the psoae. Any physical exercise performed when recovering from psoas syndrome should be discussed with a healthcare professional before attempting, as strenuous exercise may worsen the condition.

Osteopathic manipulative treatment

Osteopathic manipulative therapy involves applying gentle pressure to muscles to assist with alignment and healing.

Pain management

Over-the-counter pain management like ibuprofen can provide short-term relief.

Corticosteroid injections

These steroid injections provide pain relief and reduce inflammation and swelling. Similar to diagnosis by lidocaine challenge test, a healthcare professional would use an ultrasound to guide the injection into the psoas using a freehand technique. This can provide long-term relief. These injections are especially helpful to those experiencing psoas syndrome after a hip replacement, preventing the need for further surgery.

Surgical release of the psoas tendon

Also called a tenotomy. The tendon is divided to relieve pain and lengthen it. It’s only to be performed in severe cases. Other methods of treatment should be tried before resorting to surgery.

Prevention

Psoas syndrome can be prevented in athletes if the following measures are taken:

• Stretching before exercise
• Increasing flexibility
• Improving posture
• Gradually increasing exercise intensity, rather than suddenly performing an intense workout

To prevent psoas syndrome from developing after a hip replacement, doctors’ advice on recovery should be followed. This includes walking, working with a physiotherapist, resting, avoiding low chairs, not crossing your legs, and not twisting your hips. 

Summary

• Psoas syndrome is a condition in which someone experiences back, hip, or groin pain due to inflammation or irritation in the psoas muscles
• There are two psoas muscles, starting at an attachment on either side of the lower spine and ending at the top of each of the thigh bones. These muscles assist with stabilising the spine when sitting, and flexing the thigh when standing, as well as hip movement
• Psoas syndrome occurs due to muscle overuse or trauma
• It is common in athletes, particularly dancers or runners, but it is also seen in individuals post-hip replacement
• Psoas syndrome can be diagnosed by a physical exam, an ultrasound, an anaesthetic injection into the psoas muscles to see if the pain originates from there, or an MRI
• Treatment involves physical therapy, rest, modified or reduced exercise, pain medication, and, in extreme cases, surgical release of the psoas tendon
• This condition can be prevented in athletes by stretching before exercise, improving posture, and gradually building up to intensive exercise