Avulsion injuries of the hip

What is it?

Tendon insertions pull a bone fragment off the origin or insertion of a long muscle that usually spans two joints, the hip and the knee.

What causes it?

This is caused due to teenagers still having growing parts in their bodies, called apophysis at the origin or insertion of a long muscle. This bone-tendon interface can in some situations, ,like excessive pulling forces during sprinting activities, pull off a bone fragment.

Different types

The most common muscles that can pull off and avulse, are the rectus femoris, like the photo below which pulls off at the insertion site, located just above the hip joint or at the anterior superior iliac spice (the prominent part of the pelvic bone), or it can pull off the origin of the hamstrings muscles, on the bit of pelvic bone we sit on, the ischial tuberosity.

Symptoms

The teenage child will experience sudden onset of pain around the pelvis or hip. Movements of the hip will cause discomfort and pain and the patient might also complain of swelling and bruising in or around the pelvis.

Possible complications

These are rare and include persistent pain or swelling at the avulsion site. If symptoms persist more that 6-8 weeks, further orthopaedic review is warranted. Large local excess ossification, called heterotopic ossification can rarely occur which can cause discomfort and might require surgical excision, in rare cases where these are very symptomatic.    Other recognised complications rarely occur when the bone fragment avulsed travels a larger distance from the insertion point which prevents it from healing to the avulsion site and can in the long term cause issues with muscle function.

Differential diagnosis

Another diagnosis which can mimic these avulsion injuries around the hip joint in the early very early teenage years is Slipped Capital Femoral Epiphysis (SCFE). This is a paediatric orthopaedic emergency which needs urgent attention, therefore for any symptoms around the hip joint, the child needs to be seen quickly and a plain radiograph performed for an accurate diagnosis.

How can it be diagnosed?

A plain Xray is needed of the affected site. This will provide sufficient information for a correct diagnosis and guide optimal management. More advanced imaging in the initial acute stage is not warranted.

Treatment options

The gold standard for treating these injuries is rest from contact activities, which includes running or jumping. Patients can use crutches which can provide support and take regular analgesia until symptoms ease down. Physiotherapy is also indicated to start to allow muscle conditioning procedures to be commenced which will allow an earlier return to activities. Surgery is indicated only in very rare occasions when the muscle insertion heals with excess bone formation or when the distance travelled by the avulsion fragment is too large.

Recovery

This is done with the guidance of a physiotherapist. This is to be started soon to not allow the affected muscles to atrophy.

How can it be prevented?

Injury prevention programmes are very helpful in reducing the incidence of these injuries. Dynamic stretching before contact activities, like running-sprinting, football, rugby or any other activity which involves sudden sprinting moments significantly help reduce the incidence of such injuries.

Frequently asked questions

Q: Do I need an MRI scan?
A: No, a simple Xray of the pelvis is sufficient in providing the necessary information. If symptoms should become long lasting after 6-8 weeks a further review is warranted and this might recommend more advanced cross-sectional imaging.

Q: How long should the symptoms last for?
A: The first 2 weeks are more troublesome, with pain and limitation of movement in and around the hip and thigh muscles. This should slowly improve with physiotherapy input and progressive range of movement exercises. After 6 weeks the pain and function of the muscles should improve.

Q: Is this going to cause future issues?
A: A full resolution of symptoms and return to full activity is expected to occur after approximately 2 months.