Can a Clinician Accurately Diagnose Iliopsoas Tendinitis on a Physical Examination?

Iliopsoas (IP) tendinitis is an underrecognized but important cause of anterior hip pain in active patients. Some studies have reported that a physical examination (PE) has limited reliability in making a diagnosis of IP tendinitis. Differentiating anterior hip pain due to IP tendinitis from intra-articular sources is critical to appropriately and expediently treat patients.

PE techniques can detect IP tendinitis, and we sought to quantify the diagnostic utility of these techniques using responses to an ultrasound-guided anesthetic injection as the reference standard.

Cohort study; Level of evidence, 3.

Charts from a single surgeon's practice were reviewed. Patients with suspected IP tendinitis who received an ultrasound-guided IP bursa injection were included. A pain reduction ≥50% immediately or at first follow-up defined the positive reference standard. Recorded PE variables were absolute and relative seated hip flexion (SHF) weakness, pain with SHF, and absolute and relative tenderness to palpation (TTP) of the IP tendon. Radiographs were systematically reviewed for relevant parameters and concomitant abnormalities, and magnetic resonance imaging (MRI) scans obtained within 12 months of the diagnosis were examined for changes consistent with IP tendinitis. Diagnostic accuracy statistics were calculated.

A total of 135 injections in 105 patients (mean age, 41.2 ± 15.4 years; 74.8% female) had follow-up; 77.8% had true positive results. Absolute SHF weakness showed 96.2% sensitivity and a 77.1% positive predictive value (PPV). Relative SHF weakness yielded 82.2% sensitivity, 24.1% specificity, and a 79.0% PPV. Pain with SHF demonstrated 76.1% sensitivity and a 76.9% PPV. Absolute TTP reached 92.6% sensitivity and a 74.6% PPV, whereas relative TTP showed 86.6% sensitivity, 18.5% specificity, and a 76.3% PPV. MRI abnormalities were present in 18.1% of scanned hips, producing 19.2% sensitivity and 85.0% specificity.

Weakness or pain during SHF and direct TTP of the IP tendon were highly sensitive and predictive for IP tendinitis, whereas MRI was poorly sensitive and should be considered for ruling out other sources of hip pain. Ultrasound-guided injections may be helpful both diagnostically and therapeutically. A focused PE can allow for a rapid, accurate diagnosis.