1 Introduction

Hip pain is a common presentation in older adults, often following a fall or injury with fracture of the hip or pelvis. Atraumatic hip pain is less common, and differential diagnosis includes infection, malignancy, or flare-up of arthritis. Iliopsoas tendon injury is rare cause of hip pain, with an estimated prevalence of 0.66% in one study.¹ The same study identified that Iliopsoas tendon rupture (IPTR) in a young patient is usually related to sports or athletic injury. Rarely, spontaneous IPTR has been identified as a cause of atraumatic hip pain in older adults, and so should be considered in the differential diagnosis of an elderly patient with acute atraumatic groin pain.

Magnetic resonance imaging (MRI) enables early definitive diagnosis of this condition,² by providing cross-sectional imaging of the area to allow for early diagnosis of occult fracture, malignancy, or IPTR.² Ultrasound of the hip can also help in evaluation of iliopsoas tendon pathology but can be more difficult due to the tendon's deep location.⁵

There is paucity of literature describing the risk factors for spontaneous IPTR, although the condition has been associated with the use of fluoroquinolones³ or steroids, and chronic disease. Spontaneous ITPR appears to be most common in elderly females.¹ We describe a rare case of bilateral sequential spontaneous ITPR in an elderly female with no obvious other predisposing risk factors.

2 Case report

A 94-year-old female presented to the Emergency Department with a 5-day history of atraumatic left hip and groin pain. She was unable to weight bear or straight-leg raise on the left side. Her medical history included abdominal aortic aneurysm, heart failure, atrial fibrillation, hypertension and osteoarthritis. Plain radiographs of the pelvis and hip demonstrated no fracture, hip arthritis, or bony lesions to explain her symptoms. An MRI of her pelvis and hip was arranged, which revealed a rupture of the left iliopsoas tendon at the level of the lesser trochanter (Figs. 1 and 2). The left sided IPTR was managed non-operatively with analgesia, physiotherapy for supervised mobilisation, and core strengthening exercises. She made good progress over the next 4 weeks to the extent that the pain had fully settled.

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Fig. 1 Left ITPR as seen on T2-weighted transverse MR imaging.

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Fig. 2 Left ITPR as seen on coronal STIR MR imaging.

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Two months later, the patient presented again to the Emergency Department, this time with atraumatic onset of right groin pain. She was unable to straight-leg raise on the right and was struggling to mobilise due to pain. Plain radiographs of the hip and pelvis again found no explanation for her symptoms. MRI of her pelvis this time revealed rupture of the right iliopsoas tendon at the level of the lesser trochanter (Figs. 3 and 4) Again, she progressed well with non-operative management of the right IPTR, making a full return to her baseline mobility with significant improvement in pain.

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Fig. 3 Right ITPR as seen on T2-weighted transverse MR imaging.

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Fig. 4 Right ITPR as seen on coronal STIR MR imaging.

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3 Discussion

Stark et al. (2020) reported on 14 previous cases of spontaneous IPTR.⁴ Smith et al. (2016) reported a case of spontaneous IPTR associated with prolonged use of ciprofloxacin3. To our knowledge, our patient review highlights the first reported case of bilateral spontaneous IPTR not associated with fluoroquinolone or steroid use. Like other case reports of spontaneous atraumatic ITPR, our patient was an elderly female, but it remains unclear why this patient group has an increased incidence of this condition.

Atraumatic IPTR is an uncommon cause of hip pain in the elderly, and so a high index of suspicion and awareness of this as a differential diagnosis is needed for early diagnosis and prompt treatment of IPTR. We would suggest consideration of MR imaging in the elderly patient with atraumatic hip pain, for whom plain radiographs fail to give a diagnosis. This would allow for prompt diagnosis of Iliopsoas tendon pathology, and also help to exclude occult fracture or malignancy. In our patient, ITPR was clinically suspected when she presented with similar symptoms in the right groin only a few months following left-sided ITPR, which we believe reduced time to diagnosis and allowed for earlier treatment.

With the increasing use of MRI to assist in investigation of atraumatic hip pain, we suspect that detection of IPTR will increase. Based on previous case reports and our own experience, IPTR responds well to conservative management with analgesia and physiotherapy.¹,⁶ Given that our patient had complete resolution of symptoms with conservative management, we did not see any indication to arrange follow-up imaging. This case highlights the need to consider ITPR as a possible diagnosis in the elderly adult presenting with atraumatic hip or groin pain, even in the absence of recognised risk factors. It also provides further evidence of favourable prognosis. With early diagnosis and conservative treatment.

4 Informed consent

The patient lacked capacity to give consent for publication of this case report, but her daughter has given informed consent for this report to be published.

Financial support and sponsorship

No financial support or sponsorship to report.

Authorship contributions

Dr Michael Gillan: Wrote report, made revisions, reviewed existing literature Mr Donald Buchanan: Conceived report, supervised writing of report and made revisions Mr Kiran Singisetti: Conceived report, supervised writing of report and made revisions.