A Review of Hip Apophysitis in Athletes
A healthy, 16-year-old female presents with pain over her lateral hip and over her “hip pointer” region that has been progressive. She is a gymnast and her training has increased in frequency and intensity due to an upcoming competition. Her pain seems to get worse with her running and jumping activities and seems to improve with rest. On physical examination, there is tenderness over the left iliac crest region on palpation. Actively flexing her hip causes pain and she has weakness in hip flexion. Radiographs were read as normal. What is the most likely diagnosis?
A. Iliac crest apophysitis
B. Adductor strain
C. Ischial tuberosity avulsion fracture
D. Hamstring tendinopathy
Approximately one-third of school-aged children visit a health care professional each year for a sports injury and apophysitis is responsible for a large percentage of these visits . Apophysitis results from a traction injury to the cartilage and bony attachment of tendons in children and adolescents. Most often it is an overuse injury in children who are growing and have tight or inflexible muscle tendon units. In children and adolescents, the physeal plate is two to five times weaker than the surrounding fibrous structures (ligaments, tendons, and joint capsule), and therefore more vulnerable to injury .
There have been different terms to describe injury surrounding areas in an immature skeleton and many refer to them as “growth plate injuries.” Apophysitis is a tuberosity stressed in traction; epiphysitis is a compression or shear injury, whereas epiphyseolysis is the widening of a growth plate under stress.
The apophyses are secondary growth centers that serve as attachment sites for tendons. It has been theorized that apophysitis may have multifactorial origins in nature, including rapid growth, genetics, anatomic properties, and accumulation of microscopic avulsions. However, none of these factors appear to be predominant, and it is a possibility that all are involved in generating both an inflammatory and a degenerative response in the apophyseal cartilage .
There are seven apophyseal locations in the developing pelvis (Figure 1). The anterosuperior and anterior inferior iliac spines (i.e., sartorius and rectus femoris origins, respectively), the iliac crest, and the ischial tuberosity (i.e., hamstring) are at risk of injury in running, kicking sports, and dancing . Injuries can result from acute avulsion, blunt trauma, or chronic traction . An avulsion fracture occurs when an apophysis is subject to strong traction and the bone can be fractured and displaced.
Patients usually sustain avulsion fractures as a result of sudden forceful contraction of the external oblique, the transverse and the internal oblique muscles which insert on this apophysis. This can occur with running or jumping. Following avulsion, lateral and inferior displacement can occur due the tension of the tensor fascia lata and gluteus medius. The broad muscle insertions of the pelvis usually limit the amount of displacement .
As with other musculoskeletal conditions, history and physical examination play a key role in diagnosis. It can be somewhat challenging, but iliac crest or hip apophysitis normally occurs in individuals aged 14-16. It is more common in active teens and sports such as rugby, hockey, tennis, dance and running sports. The athlete or patient will usually report pain over the iliac crest during activity that worsens with prolonged or intense activity. Sometimes the pain can continue after activity and be bothersome at night. Normally pain will be improved with rest and sleep and reoccurs with activity. With apophysitis, normally there is no acute injury. However, there is usually an acute “pop” or pain with avulsion fractures and this many times occurs with a sudden jump or intense movement. Repetitive or new drills or actions may be present and it is valuable to ask further questions, as many sports injuries occur when athletes do things too soon, too quickly or too much.
Physical examination also plays a key role. As mentioned earlier, there are seven sites where iliac crest apophysitis is possible. The ASIS, AIIS and ischial tuberosities are more common and these should be palpated, as with the other areas. The provider should examine strength and motion, as these may be decreased in some cases. There is often pain at the apophysis with certain muscle contractions depending on muscle origin and insertion. The hip and lumbar spine should also be evaluated fully to ensure the issue is not originating from there.
Radiographs are often the first line of imaging and are useful to evaluate separation of the iliac crest from the remaining iliac bone. However, in young kids whose iliac crest apophysis is still cartilaginous (iliac crest apophysis ossification typically starts at 13-15 years old), radiographic or even CT imaging may miss the diagnosis. In patients with apophysitis and no avulsion, X-rays appear normal.
MRI (Magnetic Resonance Imaging) is a more sensitive test to detect iliac crest apophysitis. Although the MRI findings of apophysitis can be variable, the initial findings include low signal intensity on T1-weighted sequences with increased signal intensity in fluid-sequences, bone marrow edema, and mild enlargement of the physis . After healing, there can be hypertrophic ossification and residual sclerosis.
Office based ultrasonography is user dependent but can show a widened and fragmented apophysis and provide contra- lateral comparison. Ultrasonography has no radiation risk, is more sensitive than plain radiography, and can confirm the absence of a muscle and tendon injury .
No clear guidelines for the treatment of avulsion fractures have been established in the available literature. Treatment is often conservative with nonsteroidal anti-inflammatory drugs, rest, decrease strenuous activity, and physical rehabilitation. Recovery is expected within 4-6 weeks, at which time the patient or athlete can resume gradually their sports activities. There are reports of full recovery taking up to 12 weeks. Some will use non weight bearing or protected weightbearing with crutches for 1-4 weeks. Running is avoided and emphasis is placed on strengthening core or postural muscles and improving flexibility of the long muscles crossing the pelvis. Ultimately, symptoms will remit as the iliac crest apophysis fuses to the ilium. Conventional radiography occasionally is used to confirm resolution as symptoms improve.
Failure to detect these injuries or noncompliance with conservative treatment may also result in malunion or nonunion. Surgery may be rarely needed in patients with markedly displaced iliac crest avulsion (more than 3 cm), or if there is evidence of vessel or nerve encroachment. Li et al. described a series of 10 adolescent athletes who underwent operative treatment and the average full athletic activity was resumed in four weeks. The authors proposed early open reduction and internal fixation in high level athletes to hasten recovery .
In a meta-analysis, Eberbach et al. indicate that the overall success rate and return to sport were higher in patients who underwent surgery, especially in patients with fracture displacement greater than 1.5 cm. The mean recovery time was 3.1 months in patients treated conservatively and 2.4 months in patients treated surgically .
In summary, apophysitis over the hip or pelvis can present with a history of prolonged, sometimes vague symptoms involving the pelvis, hip, or lower back. There can be an acute avulsion with a high energy motion or stress. Consideration for a possible stress injury to the iliac crest apophysis should alert one to carefully evaluate this region with physical examination and further imaging if deemed appropriate. There is no consensus or large randomized trials with treatment, but most patients will respond well to conservative measures if displacement is less than 3 cm.
The patient is most likely suffering from iliac crest apophysitis in the vignette. She does not have any weakness with adduction and there is no mention of tenderness over the pubic symphysis. Radiographs were normal along with no mention of tenderness over the ischial tuberosity, making an avulsion fracture over the ischial tuberosity or hamstring tendinopathy less likely.
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