Teaching Case

An adolescent male, 14-year-old, and a member of a private football academy, presented with pain at his sitting bones. The pain was initially related to training and then became persistent all the time and manifested severely while sitting, standing, and kicking. He had to suspend training and seek medical advice. At clinical examination, exquisite pain was limiting active hip flexion and extension. The maximum point of tenderness was at pressing on sitting bones. No muscle wasting, leg deformity or gait abnormality. Neurological examination was free.

Plain X-ray of the pelvis demonstrated bilateral irregular cortical margins of the ischial tuberosities with no definite displaced avulsed bone fragments (Figure 1a and 1b).  Magnetic Resonance Images (MRI) revealed bilateral symmetrical ischial tuberosity bone oedema associated with intrasubstance oedema at the hamstring tendon origin (Figure 2a and 2b).

An apophysis is the anatomical site of a tendon attachment to bone in the skeletally immature. The ischial tuberosity apophysis hosts the hamstring tendons attachment. Ossification starts to appears after the age of 10 years in girls and 11 years in boys, with complete fusion is observed at the age of 16.9 and 17.8 years old in girls and boys respectively [1].

Sports injuries at the ischial tuberosity apophysis are common especially in football players. Acute avulsion injuries are the most encountered type of injury and are commonly described in literature in its acute and chronic clinical presentations [2–5].

Ischial apophysitis is a description of a clinical condition in which there is painful ischial apophysis in absence of avulsion. It is more common in athletes secondary to continuous tendon traction on growing bone and cartilage implying a form of stress and repeated microtrauma [2, 6]. The underlying pathogenesis is osteochondrosis, which is basically a disorder of growing cartilage at the long bone physeal growth plate, epiphyses or apophyses. It is of uncertain aetiology, but several factors have been suggested including vascular, hormonal, genetic factors. There is a strong association with the increased physical activities in adolescents and hence more common incidence among athletes [7]. Apophyseal osteochondrosis is commonly seen at the tibial tuberosity, “Osgood Schlatter disease” and also at the calcaneum, “Sever disease”. The incidence of ischial apophysitis is unknown. Few case reports are published [8–11].

Pelvis radiographs may be inconclusive. Asymmetrical appearance of the apophyses compared to the normal side may be helpful at showing some widening, sclerosis, cortical irregularity. MRI is the best imaging investigation to diagnose this condition, exploiting oedema at the anatomical site of tendon attachment, with the superior ability to show any tendon damage like degeneration or tear. It is important to differentiate these findings from the more common avulsion injury pattern which is usually an acute injury having a bone fragment is displaced from the original bone. Computed tomography (CT) would show irregular margins and possible fragmentation of the apophyseal margins. However, it is better to avoid unnecessary exposure in such age groups. Bone scintigraphy may show locally increased tracer uptake.

The diagnosis of ischial apophysitis implies rest and rehabilitation. In most cases, the condition is self-limiting and no intervention is required [6, 8].