Continuing Education Activity

Psoas syndrome refers to pain and dysfunction from irritation, inflammation, or injury to the psoas or iliopsoas muscle group. The condition commonly affects individuals involved in repetitive hip flexion, particularly runners, dancers, and high jumpers. Nonathletes may be affected due to prolonged sitting, poor posture, or spinal conditions. Less common causes include psoas abscess and retroperitoneal malignancy, which should be considered in atypical or refractory cases.

Mechanical strain of the iliopsoas can cause spasm, inflammation, or fibrosis. Tendon snapping over bony structures leads to anterior or internal snapping hip syndrome (coxa saltans or “dancer’s hip”). Psoas syndrome may coexist with tendonitis or follow total hip arthroplasty. Patients typically report deep anterior hip or groin pain, worsened by hip extension or resisted flexion. Pain may radiate to the thigh or lumbar region, and snapping may be audible or visible. Adolescent athletes are particularly susceptible during growth spurts.

Diagnosis is clinical, supported by maneuvers such as the Thomas test and resisted straight-leg raise. Imaging helps rule out abscess or malignancy. Initial management includes rest, nonsteroidal anti-inflammatory drugs, physical therapy, and activity modification. Refractory cases may need corticosteroid injections. Surgical tendon release is reserved for rare, persistent symptoms.

This activity for healthcare professionals is designed to enhance learners' competence in evaluating and managing psoas syndrome. Participants will broaden their grasp of the condition's etiology, pathophysiology, and clinical presentation. The best diagnostic and therapeutic practices will also be covered. Greater proficiency will equip clinicians to collaborate within an interprofessional team caring for affected individuals.

Objectives:

• Differentiate psoas syndrome from disorders with overlapping manifestations based on clinical and diagnostic features.
• Develop personalized, evidence-based treatment plans for patients with psoas syndrome.
• Improve communication approaches to educate patients with psoas syndrome on its causes, symptoms, treatment options, and the importance of activity modification and rehabilitation for better management adherence.
• Implement effective collaboration and communication among interprofessional team members to improve outcomes and treatment efficacy for patients with psoas syndrome.

Introduction

Psoas syndrome involves pain and inflammation of the distal iliopsoas tendon, with lesser involvement of the distal muscle, often affecting the psoas bursa and tendon sheath. The condition commonly occurs in athletes, such as runners, dancers, and high jumpers, typically due to overuse or trauma. However, psoas pain can also stem from infections, including tuberculosis, or malignancies.[1] Additionally, psoas syndrome can affect sedentary individuals of all ages, "weekend warriors," or those with conditions that lead to flexion contractures, such as spinal cord injury, multiple sclerosis, or cerebral palsy.

Groin pain is a frequent symptom, particularly in sports involving kicking or during adolescent growth spurts. The condition may follow iliopsoas tendonitis after total hip arthroplasty (THA) and may coexist with iliopsoas bursitis or other musculoskeletal issues. Terms like psoas dysfunction, iliopsoas tendinitis, internal snapping hip, or iliopsoas impingement are often used interchangeably.

Most patients improve with conservative treatment. In more persistent cases, particularly where athletes resist rest, nonsteroidal anti-inflammatory drugs (NSAIDs), a course of oral steroids, corticosteroid injections, or surgery may be necessary. Advanced imaging or electromyography may also be considered. Healthcare providers should consider psoas syndrome in the differential diagnosis of anterior hip or groin pain.

Etiology

Athletes, particularly runners and those engaging in plyometric exercises (eg, kick boxers, mixed martial arts fighters, tennis and soccer players), are predisposed to psoas syndrome due to repetitive hip flexion, often against a resisting force.[2] The pubic tubercle, commonly mentioned only briefly in anatomy courses, may play a critical role in anterior (or internal) snapping hip phenomena and distal psoas tendinopathy. Psoas tendinitis or syndrome may also affect individuals with inflammatory or degenerative arthritis and may result from impingement of the psoas tendon against an oversized acetabulum.[3][4] Postoperative complications, including psoas tendinitis, may arise from factors like recurrent hematomas in the iliopsoas tendon or protruding surgical screws.[5][6][7]

Anatomically, the psoas muscle originates from the transverse processes of the lower lumbar spine and inserts along the pelvis and femur, primarily enabling hip flexion and external rotation of the leg.[8][9][10] The iliac muscle attaches proximally along the inner surface of the ilium, and both muscles insert on the lesser trochanter of the proximal femur.[11] In approximately 15% of individuals, the iliopsoas bursa communicates with the hip joint. During physical examination, movement of the iliopsoas tendon from medial to lateral on the femoral head can cause snapping or clunking, leading to inflammation and fluid accumulation in the bursa, resulting in pain.

A less common etiology for psoas syndrome is malignant invasion into the psoas muscle, termed "malignant psoas syndrome."[12][13] First reported by Stevens and Gonet in 1990, this condition typically arises in individuals with previously diagnosed, advanced-stage malignancy. Malignant psoas syndrome is characterized by painful fixed hip flexion, proximal lumbosacral plexopathy, and computed tomography (CT) evidence of tumor infiltration into the psoas muscle, resulting in severe pain and symptoms that vary based on the extent of anatomical involvement.[14][15]

Epidemiology

The true incidence and prevalence of psoas syndrome in the general population remain unknown, likely due to frequent underdiagnosis, misdiagnosis, and symptom resolution before clinical evaluation. Female athletes appear to have an increased risk, possibly due to a wider osseous pelvis. Additional risk factors include hip osteoarthritis and rheumatoid arthritis. While hip pain is relatively common in individuals aged 60 years or older, psoas syndrome represents an uncommon etiology in this age group.

More data are available for psoas abscess. In a study involving 40 patients, the mean age was 60 years, and 67.5% of cases occurred in men. The in-hospital mortality rate was 5%. Half of the cases were secondary to infective spondylitis. Staphylococcus aureus was the most common causative organism, followed by Escherichia coli. Polymicrobial infections were typical in secondary abscesses.[16]

Postoperative iliopsoas syndrome has been reported in 4.3% of individuals following THA.[17][18] Additionally, a study of 252 patients undergoing THA found iliopsoas tendonitis in 24% of cases.[19]

Pathophysiology

Benign psoas syndrome typically results from stretching of the iliopsoas tendon, which may snap over the ipsilateral pubic tubercle, eliciting pain during hip extension. In contrast, infectious or malignant causes present with variable pathophysiology depending on the extent and progression of the underlying condition. Infectious cases often originate from a primary spinal source, such as vertebral osteomyelitis, that extends to involve the psoas muscle.

History and Physical

Patients typically present with anterior groin pain exacerbated by hip flexion. Axial spine discomfort may also occur in the lumbosacral region due to altered gait mechanics. Pain can radiate into the sacrum and may be accompanied by discomfort in the buttocks, pelvis, or lower back.[20] Some patients report a sensation of catching or slipping in the groin when the knee is flexed to 90°. Although this symptom often suggests a labral tear, it is also characteristic of iliopsoas tendinopathy.

A standard motor strength and reflex examination, including deep tendon reflexes, should be performed, along with assessment for upper motor neuron signs, muscle atrophy, and both dermatomal and peripheral sensory changes. A thorough history should explore recent changes in workout routines, new athletic equipment, and coaching techniques to identify possible mechanical triggers. To evaluate for more serious pathology, clinicians should ask about prior malignancies, history of spinal injections (particularly discography), and intravenous drug use. The review of systems should screen for constitutional symptoms such as fever, chills, weight loss, or night sweats.

Clinicians should maintain a low threshold for ordering diagnostic laboratory tests, including urinalysis, complete blood count with differential, erythrocyte sedimentation rate, and C-reactive protein. A human chorionic gonadotropin test should also be considered. Standard vital signs must be recorded, and additional questions should address intravenous drug use, unexplained weight loss, prior ovarian cysts, or other gynecologic conditions.

Since the iliopsoas muscle is a primary hip flexor with proximal attachments along the lumbar vertebrae, individuals with psoas syndrome often report lower back pain during ambulation. Pain is commonly triggered by positional changes, such as transitioning from a seated to a standing position, or difficulty maintaining an upright posture. Some may also experience contralateral gluteal pain. Symptoms generally worsen with activity and improve with rest. Radiating pain typically does not extend beyond the knee.

A detailed medical history is essential. Although malignant psoas syndrome remains a rare consideration, metastatic spread to the psoas muscle must be ruled out. Thorough history-taking also helps exclude other potential causes of similar symptoms.

Patients typically do not present with overt difficulty ambulating. However, subtle signs such as a limp, slow transitions from sitting to standing, or a shuffling gait may be observed. Gait assessment should be conducted passively, without alerting the patient, to avoid performance bias. Tightness or hypertonicity of the hip flexors, particularly the quadriceps, may be present. A positive Ely test—performed with the patient in the prone position and the knee passively flexed—is indicated when the foot fails to touch the buttocks. Palpation may elicit tenderness at the insertion site of the iliopsoas on the lesser trochanter. Range of motion in hip extension is often reduced, and in chronic cases, exaggerated lumbar lordosis may be observed.

Although traditionally associated with appendicitis, a positive psoas sign (pain on passive hip extension) may also indicate psoas muscle irritation, supporting a diagnosis of psoas syndrome. A positive Ludloff sign—elicited by having the patient sit with the knee extended and then lift the heel of the affected leg—suggests pain localized to the iliopsoas region. A snapping hip test may also yield a positive result. With the affected hip flexed, externally rotated, and abducted, passive hip extension may reproduce pain, supporting the diagnosis of psoas syndrome.

Evaluation

X-rays and CT scans of the hip are often unremarkable and unnecessary in diagnosing psoas syndrome, unless malignant psoas syndrome is suspected. In such cases, one of the diagnostic criteria set by Stevens et al involves CT imaging showing pathological evidence of malignancy in the psoas muscle.

Acute inflammatory markers, such as the erythrocyte sedimentation rate and non-cardiac C-reactive protein, should be assessed. For potential infection, a complete blood count with differential and platelet count is recommended. A thorough history regarding past or active intravenous drug use should be obtained, and a drug screen may be warranted. Additionally, urine human chorionic gonadotropin testing or an ovarian ultrasound may be indicated in cases of unexplained anterior groin or pelvic pain. A basic urine dipstick, particularly for assessing blood, is an inexpensive and rapid method to help narrow the differential diagnosis in unclear cases, especially when sports-related risks are not present.

Ultrasound can aid in differentiating between intraarticular and extraarticular causes of hip pain.[21] A lidocaine challenge test under ultrasound or fluoroscopic guidance may also be helpful in diagnosing psoas syndrome. During this test, lidocaine is injected into the psoas tendon, and a reduction in pain following the injection supports the diagnosis of psoas tendonitis (or syndrome).

In 21% of athletes with groin pain, iliopsoas pathology is detectable on magnetic resonance imaging (MRI).[22] If conservative management for a suspected iliopsoas injury fails, an MRI may help confirm the diagnosis. MRI and ultrasound often reveal bursa enlargement and thickening of the iliopsoas tendon.[23]

Laboratory tests are typically unnecessary in benign psoas syndrome, as the condition is primarily an overuse and mechanical issue without changes in autoimmune markers.[24] Electrodiagnostic evaluation, including nerve conduction studies of the lateral femoral cutaneous nerve, should be considered in cases of anterior thigh pain and potential overlapping meralgia paresthetica.[25] Needle electromyography, often performed as part of an electrodiagnostic evaluation, may also be relevant in cases of diffuse leg pain, high lumbar radiculopathy, or diabetic amyotrophy.[26]

Treatment / Management

First-line treatment for psoas syndrome involves physical therapy focused on stretching the iliopsoas hip flexor group, strengthening the spinal and hip musculature, and identifying any triggers in the training routine that may have caused the tendinopathy. A study found that 100% of dancers responded to conservative management. Exercise programs, particularly those targeting hip rotation, have proven effective in reducing pain and improving activity for patients. Over-the-counter pain medications such as ibuprofen and acetaminophen should be continued.[27] Modalities like heat, ice, therapeutic ultrasound, and electrical stimulation may be used if beneficial and continued empirically based on clinical response.

For athletes, adequate rest and cross-training are crucial to avoid further strain on the hip flexors, though activity modification can be one of the most challenging aspects of care. Runners and field players may benefit from aquatic therapy, particularly when the water depth reaches the midsection, which reduces pressure on the psoas while providing hydrostatic compression and allowing for a sense of continued exercise. In cases of suspected groin pain due to iliopsoas tendon injury, an MRI may be warranted for return-to-play decisions. MRI findings consistent with muscle strain correlate with a significantly reduced return-to-play rate compared to those with peritendinitis changes.

Osteopathic Manipulative Therapy (OMT), therapeutic ultrasound, corticosteroid injections, and, in refractory cases, surgical release of the psoas tendon are treatment options for psoas syndrome.[28] Ultrasound-guided injections can serve both diagnostic and therapeutic purposes in cases of hip pain with an unclear origin.[29][30]

For refractory cases requiring surgery, arthroscopic lengthening of the tendon can provide relief, and correction of any intraarticular pathology may also be necessary.[31] Additionally, releasing the psoas tendon from its insertion is a potential surgical option. Various approaches to surgical release have been attempted and studied, yielding similar results. Among patients who developed postoperative iliopsoas tendonitis following THA, 24% required a corticosteroid injection for pain relief, while 12% needed revision surgery or iliopsoas tendon release.

In contrast, the treatment of malignant psoas syndrome differs significantly. Management focuses on pain relief through opiates, muscle relaxants, anti-inflammatory medications, nerve blocks, epidural anesthesia, chemotherapy, radiotherapy, and, if necessary, surgery.[32] Addressing the primary tumor with gold standard treatment modalities remains critical.[33]

For infections, antibiotic therapy and, possibly, antituberculosis treatment are indicated. An infectious disease consult may likewise be necessary, as well as potential neurosurgical intervention for underlying spinal infections. General or vascular surgery may be required for abscess management. If the abscess is clearly loculated, interventional radiology may place a drain and obtain a sample for culture to guide antimicrobial therapy.

Differential Diagnosis

The differential diagnosis of anterior hip or inguinal pain is broad and can be sex-dependent. Symptoms of psoas syndrome often mimic those of a symptomatic herniated disc, hernia, ovarian cyst, or lumbar region issues. Other musculoskeletal conditions to consider include hip arthritis and femoral bursitis. Snapping hip syndrome, or coxa saltans, should also be included in the differential.[34]

Visceral causes of pain can present similarly to psoas syndrome, including prostatitis, diverticulitis, salpingitis, pregnancy (ectopic and others), nephrolithiasis, and various other visceral etiologies. A well-respected text on the diagnosis of right lower quadrant pain specifically includes psoas tendonitis in the differential.[35] Additionally, a labral tear of the hip may present with a catching or slipping sensation, as well as pain reproduction with knee flexion, making it difficult to distinguish from psoas syndrome during examination.

Medial to the psoas muscle lies the ureter. Consequently, patients with a renal stone often experience symptoms similar to psoas syndrome due to irritation of the psoas muscle from a stone within the ureter. Similarly, the appendix can lie anterior to the psoas muscle. Thus, the psoas muscle may also become irritated in some cases of appendicitis.

A significant overlap exists between snapping hip syndrome, psoas syndrome, iliopsoas bursitis, hip impingement, iliopsoas tendonitis, and hip labral pathology, which can complicate diagnosis and treatment. On examination, weakness in hip flexion of an abducted hip may be seen in both snapping hip syndrome and iliopsoas syndrome.

Finally, malignant psoas syndrome should remain in the examiner’s differential. The condition should not be overlooked, even though it is rare and often accompanied by other presenting symptoms or a history of primary cancer.

Toxicity and Adverse Effect Management

Conservative management and therapies carry a few real risks. If therapy is too aggressive early on, a flare may occur, leading to therapy cessation and potential reluctance to resume treatment. Monitoring patient tolerance and maintaining effective communication between the patient and therapist can help mitigate this risk. Therapeutic ultrasound can cause skin burns if high settings are used in nonpulsed mode and left stationary, though this incident is uncommon with trained therapists.

Injections carry risks such as vascular or nerve injury, steroid reaction, and pain. Fluoroscopy typically utilizes a contrast agent, which can cause renal toxicity. However, the dose is generally limited to 1 to 2 mL. Ultrasound guidance may fail to detect inadvertent vascular uptake, and aspiration for blood has proven inadequate for ruling it out.

Bupivacaine (Marcaine) has higher cardiac toxicity than lidocaine in cases of inadvertent vascular uptake, a risk mitigated by avoiding the drug. Procedures using bupivacaine should be performed in facilities equipped with the appropriate equipment (eg, code cart) and staff trained in Basic Life Support and Advanced Cardiovascular Life Support capable of handling periprocedural complications. In rare cases where bupivacaine use is necessary, the facility must be equipped for "lipid rescue." For this reason, this anesthetic is increasingly avoided in outpatient procedural clinics.[36]

Prognosis

The vast majority of patients diagnosed with psoas syndrome due to overuse and benign etiologies respond to conservative management and have a full recovery. However, postoperative pain in the psoas muscle following THA may require more advanced treatment to restore function. Patients who undergo this procedure are typically not high-performance athletes. Therapies should include corticosteroid injections and tendon release. The prognosis of malignant psoas syndrome is notably varied depending on the degree of tumor infiltration, whether primary or secondary, and progression of the primary malignancy.

Complications

Untreated iliopsoas syndrome can lead to chronic pain and decreased athletic performance. Over time, recurrent inflammation may result in tendon degeneration and contribute to long-term functional limitations. One potential consequence includes the development of reflex sympathetic dystrophy, a form of complex regional pain syndrome that may follow chronic musculoskeletal irritation.

Recurrent tendonitis of the iliopsoas tendon is another concern, especially when mechanical contributors remain unaddressed. Ongoing inflammation may lead to a flexion contracture, resulting in secondary impairment and potential disability if not managed appropriately.

Local anesthetics and corticosteroids, although often necessary for treatment, can lead to secondary hyperglycemia. Additionally, inadvertent intravascular uptake may cause local anesthetic toxicity. This risk is heightened with using agents like bupivacaine, which has greater cardiac toxicity than lidocaine, underscoring the need for facilities equipped for emergencies, such as those with lipid rescue capabilities.

Injection-related complications also include potential damage to neurovascular structures. However, this risk is greatly reduced when procedures are performed under fluoroscopic or ultrasound guidance. Even with imaging, inadvertent vascular uptake remains a possibility, necessitating vigilant procedural technique.[37] Postprocedure complications from platelet-rich plasma (PRP) are rare and usually limited to localized effects at the injection site.

Postoperative and Rehabilitation Care

Surgical decompression is rarely indicated. Standard postoperative instructions should be followed, with therapeutic interventions reintroduced as needed based on the clinical response. After an injection, patients should rest and resume therapy only after the local anesthetic has worn off. Engaging in active therapy while a joint remains anesthetized may inadvertently exceed the intended therapeutic range. In specific circumstances, this measure is intentional, such as in Manipulation Under Anesthesia (MUA), a technique performed under the supervision of a clinician, typically for conditions like shoulder adhesive capsulitis or restricted knee flexion. Postinjection instructions following PRP therapy vary considerably depending on the provider and the stage of care.

Deterrence and Patient Education

Dancers, runners, and impact athletes face an increased risk of iliopsoas syndrome, although sedentary individuals may also be affected. Effective management often involves coordinated care among the primary care physician, physical therapist, sports medicine physician, and, when indicated, oncologist, interventionalist, or orthopedic surgeon. Home exercise programs and NSAIDs serve as first-line therapy. In refractory cases, ultrasound- or fluoroscopy-guided corticosteroid or PRP injections can aid both diagnosis and treatment. If conservative management fails, orthopedic referral may be necessary for decompression or a second opinion. Postoperative iliopsoas tendonitis is a recognized source of pain following THA.

Pearls and Other Issues

Psoas tendinopathy often results from contact between the anterior pubic bone and the distal psoas tendon. Secondary musculoskeletal conditions, such as trochanteric bursitis, meralgia paresthetica, and sacroiliac joint pain, may coexist. Anterior inguinal or groin pain encompasses a broad differential diagnosis, requiring careful evaluation to distinguish among potential causes.

Enhancing Healthcare Team Outcomes

Psoas syndrome, with its potential for significant pain and functional impairment, benefits from early intervention that may range from conservative therapy to surgical management. The condition often arises from activity-related or structural factors, exacerbated by osteoarthritis, rheumatoid arthritis, prior injury, overuse, upper motor neuron findings, or postoperative changes. A thorough history and physical examination can frequently establish the diagnosis, although musculoskeletal ultrasound or MRI may be necessary for confirmation in select cases.

Management requires coordination among interprofessional team members that may include a primary care physician, a primary care sports medicine specialist, an orthopedic surgeon, and an oncologist in cases involving malignancy. Physical therapists play a central role in conservative treatment and postoperative rehabilitation. In complex or unclear cases, consultation with a specialist can help determine the most appropriate imaging or therapeutic approach. Nurses contribute to patient care through patient education, monitoring progress, and facilitating effective communication within the care team.

An interprofessional team approach offers the best strategy for minimizing complications related to psoas tendon procedures. Before an ultrasound-guided psoas tendon injection or an iliopsoas tendon release, the patient should undergo a thorough evaluation by the primary care physician or clinician. A physical therapy consultation is essential to initiate conservative treatment and assess functional impairment. In refractory cases that do not respond to conservative management, referral to a primary care sports medicine physician is appropriate.

Further subspecialty involvement may include interventional radiology, physical medicine and rehabilitation, or pain management for guided psoas tendon injections, whether corticosteroid or PRP. Orthopedic consultation may be warranted when the diagnosis remains unclear, and surgical tendon release may be considered. In recalcitrant cases or when secondary neurological symptoms are present, an evaluation by physical medicine and rehabilitation or neurology, including electromyography and nerve conduction studies, may help identify the underlying pathology.

Infectious causes, such as a psoas abscess, require early involvement of infectious disease specialists. If aspiration or drainage is indicated, interventional radiology may be consulted. In some cases, general or vascular surgery may be required for incision and drainage procedures. Additionally, if the abscess is related to current or prior intravenous drug use, addiction medicine consultation may be necessary to support long-term care and reduce recurrence.

Outcomes for psoas syndrome are often favorable, particularly in cases related to overuse. However, prognoses for malignancy- or infection-related cases tend to be more guarded. Early recognition of the underlying etiology and timely engagement of appropriate specialists improve the likelihood of a successful recovery. Collaborative decision-making, effective communication, and coordinated care within the interprofessional team enhance both clinical outcomes and patient safety.

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Disclosure: Alexander Dydyk declares no relevant financial relationships with ineligible companies.

Disclosure: Young Hu declares no relevant financial relationships with ineligible companies.

Disclosure: Michael Stretanski declares no relevant financial relationships with ineligible companies.