Traumatic Obturator Internus and Quadratus Femoris Injury in a Pediatric Patient: A Case Report

Abstract

We present the case of a 11-year-old White female patient with a traumatic quadratus femoris and obturator internus tear after a sprint while at school. She felt immediate pain, swelling, and point tenderness in her posterosuperior thigh with a severely antalgic gait. Magnetic resonance imaging demonstrated a quadratus femoris tear, obturator internus tear, and ischial spine avulsion fracture. Although a less common etiology for acute hip pain in the pediatric population, traumatic injury to the short external rotators should not be excluded. The prognosis is favorable with a full return to previous activities expected using an appropriate rehabilitation program.

Traumatic injuries to the hip are common in athletes and the active population, representing up to 10% of all sport injuries.^1,4 Comprehensive history and physical examination can help differentiate these injuries, yet precise diagnosis often requires advanced imaging particularly when intra-articular or deep hip pathology is suspected. ¹¹

The external rotators of the hip are composed of the piriformis, obturator externus, superior and inferior gemelli, obturator internus, and quadratus femoris. This group of muscles helps to stabilize the femoral head in the acetabulum during movement and provide a uniform external rotation force despite changes in hip position or muscle length.^9,15 The quadratus femoris arises from the external aspect of the ischial tuberosity and inserts into the trochanteric crest of the femur. The obturator internus arises from the inner surface of the superior pubic ramus and obturator membrane before being reflected at a right angle over the grooved surface of the ischium where it joins the gemelli muscles (triceps coxae) to insert on the greater trochanter as a “conjoint tendon.” ¹⁵ Pathology regarding the triceps coxae or quadratus femoris typically manifests as tendonitis due to external compression or overuse.^8,13 The mechanism of acute traumatic injury to these external rotators is poorly elucidated and largely unknown, but is hypothesized as a strong eccentric contraction to help control hip internal rotation. ¹³

Little information can be found regarding traumatic injuries to the external rotator muscle group, particularly in the adolescent population. The purpose of our study was to present a traumatic injury to the hip external rotators in a pediatric patient.

Case Presentation

A healthy 11-year-old girl presented to clinic with left hip and buttock pain after injuring herself while running at school. She was sprinting during physical education and heard a “pop” with immediate pain in her left posterior hip. On physical examination, there was mild swelling of the left posterior thigh without discrete ecchymosis and tenderness to palpation of the posterior thigh and hip. The patient was unable to tolerate weightbearing on her left lower extremity, and passive flexion was limited to 100° secondary to pain. Symptoms were reproduced with gentle hip flexion and internal rotation. There was no tenderness at palpation of the sacroiliac joint, iliotibial band, greater trochanter, or hip adductor muscles. Resistance testing demonstrated full strength in all muscle groups of the lower limb except for hip abduction and extension, which were limited by pain. The patient was neurovascularly intact distally. She reported no prior injury or pain in her left hip.

Radiographs of the pelvis and left hip were negative for acute osseous abnormality. Given the history and mechanism of injury, there was concern for an avulsion of the hamstring tendon. A magnetic resonance imaging (MRI) was obtained, which demonstrated a small cortical avulsion of the left ischial spine with associated subperiosteal hematoma and tears of the obturator internus and quadratus femoris (Figures 1-5). There was no evidence of labral injury, stress fracture, or sacroiliac disease, although a small hip effusion was present.

Figure 1.

Axial T2 magnetic resonance imaging sequence demonstrating ischial spine avulsion fracture (white arrow) and subperiosteal hematoma.

Figure 2.

Axial T2 magnetic resonance imaging sequence demonstrating elevation and focal disruption of the periosteum (white arrow). Immediately beneath an obturator internus tear with surrounding muscle belly edema.

Figure 3.

Sagittal T2 magnetic resonance imaging sequence demonstrating an obturator internus tendon tear (white arrow).

Figure 4.

Coronial T2 magnetic resonance imaging sequence showing a quadratus femoris tendon tear and surrounding edema (white arrow).

Figure 5.

Sagittal T2 magnetic resonance imaging sequence demonstrating quadratus femoris injury and surrounding muscle belly edema (white arrow).

The patient was treated conservatively with a rehabilitation protocol of protected weightbearing and nonsteroidal anti-inflammatory medication. She experienced complete subsidence of symptoms by 6 weeks with return to previous level of activity.

Discussion

There are few publications regarding the incidence of traumatic injury to the obturator internus or quadratus femoris, with the majority of case reports involving the short external rotators in adult soccer or tennis players.^{3,6,10,12,14,16} Symptoms can manifest as groin, gluteal, hip, or posterior thigh pain usually with difficulty during ambulation.

To date there are no described cases of injury to both the obturator internus and the quadratus femoris and only 2 other case reports of traumatic injury to the obturator internus in a pediatric patient. A 14-year-old high school quarterback sustained a right obturator internus strain as he attempted to grab a football from the ground behind him. He was treated with relative rest, gentle hip range of motion exercises, and protected weightbearing for 2 weeks, with gradual increase of his physical therapy afterward. He became symptom-free at 6 weeks and was cleared to return to play at that time. ⁷ The second case is a 13-year-old male patient who presented with acute right hip pain while attempting to kick a soccer ball. The patient was prescribed physical therapy and protected weightbearing with resolution of symptoms at 8 weeks. ²

As was the case with our patient, the clinical diagnosis can be challenging given the inconsistent localization of symptoms with injury to the hip external rotators and possible concomitant pathology such as avulsion injuries, stress fractures, or labral damage. There are no previously described injuries of the short external rotators that featured a fracture of the ischial spine; however, this did not seem to affect functional recovery. Pain during passive hip rotation or against resistance at 90° of hip flexion may be the only significant clinical findings, and as a result the use of MRI becomes essential. ⁵ Further understanding of the overall nature of these injuries in the pediatric population will help clinicians advise patients on prognosis and expected recovery.

Conclusion

Although extremely rare, traumatic injuries to the short external rotators should not be excluded for acute hip pain in the pediatric population. Here we present a unique case of injury to the obturator internus, quadratus femoris, and avulsion fracture of the ischial spine in a pediatric patient. MRI is often necessary to distinguish this unusual injury from other hip pathology and direct treatment. The prognosis is favorable with a full return to previous activities expected using an appropriate rehabilitation program.