Laboratory Studies
See the list below:
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Laboratory tests are usually not indicated for most patients with acute or chronic hip pain. Patients with constitutional symptoms such as prolonged fever, night sweats, or weight loss, or who have a history of juvenile or rheumatoid arthritis should have a complete blood cell (CBC) count, complete metabolic panel, and perhaps an erythrocyte sedimentation rate (ESR) performed.
Imaging Studies
See the list below:
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Radiography
Plain radiographs are indicated for injuries that result in immediate, significant disability. These x-rays will help the clinician to determine if a fracture or avulsion fracture is the cause of the disability. Hip joint osteoarthritis, avascular necrosis, and femoral neck stress fractures can also be diagnosed.
A 2-view radiograph, anteroposterior (AP) and lateral view of the hip, will adequately depict most clinically significant avulsion fractures. The frog-leg view is most useful for determining the presence of a stress fracture to the femoral neck. Stress fractures may be present if localized periosteal bone formation is noted in the femoral shaft or cortical breaks in the superior femoral neck. Avulsion fragments greater than 2 cm are usually an indication for surgical referrals for possible screw placement.
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Magnetic resonance imaging (MRI) [23, 24]
MRI studies are increasingly used to help aid in the diagnosis of acute and chronic hip pain. MRIs show good definition for large muscle and tendon tears and aid in providing prognostic information based on the presence of edema, blood, or large fluid collections. In addition, the presence of large areas of tendon inflammation and degeneration can often be noted. MRI also determines whether collections of fluid are present in a bursa, although greater trochanteric bursitis is often not seen on MRI. Iliopsoas bursal collections can be visualized because they tend to be larger. Stress injuries of the apophysis and stress fractures of the pelvis, femoral neck or shaft, and pelvic bones are easily visualized on MRI. Degenerative changes within the hip joint and avascular necrosis are also evident on noncontrast MRIs. Of course, neoplastic processes are best evaluated with contrast-enhanced MRI. Intra-articular labral tears can only be diagnosed with a magnetic resonance arthrogram of the hip joint. The contrast must be injected into the joint under direct fluoroscopic or ultrasound guidance, which makes this imaging test more difficult to perform. Limitations of MRI include excessive cost, increased time to obtain images, and the static nature of the test.
A study by Grimaldi that involved 65 patients with lateral hip pain reported that the probability of gluteal tendinopathy presence on MRI moves from 50% to 98% if pain is reported within 30 seconds of standing on the affected limb. [25]
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Bone scanning
Radionuclide triple-phase bone scans are indicated for the diagnosis of stress fractures anywhere in the body. These studies will typically show increased bone activity within 3 days of the commencement of the athlete's symptoms and are rarely falsely negative.
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Diagnostic ultrasound
Diagnostic ultrasound is increasingly used in the sports medicine office. [26] Ultrasound machines may be mounted on carts or are portable, and they usually contain a 6–12 mm probe, which provides for adequate visualization for most musculoskeletal complaints. Ultrasound is useful in visualizing the fluid collections that are present with iliopsoas or greater trochanteric bursitis, as well as for demonstrating hematomas from acute quadriceps strains. Tendons can easily be seen, and partial or complete tendon ruptures and avulsions can be determined.
Tendinopathy is also easily visualized with ultrasound. The ultrasound criteria for tendinopathy include enlargement of the tendon, hypoechoic and hyperechoic changes that demonstrate collagen disorganization, microcalcifications, minute tendon tears, and decreased flow within the tendon. The iliopsoas, gluteus medius, proximal hamstring, and rectus femoris tendons are all easily visualized. Dynamic ultrasound is extremely useful for the evaluation of a snapping hip to determine the exact tendon involved, such as the iliopsoas snapping over the pelvic ring, or the tensor fasciae latae snapping over the greater trochanter. Ultrasound can also be used to guide injections into fluid collections, bursae, and the hip joint, and for guiding needle-based interventions for chronic tendinopathy. Fearon et al evaluated the positive predictive value of preoperative ultrasound assessment in 24 patients with greater trochanteric pain syndrome refractory to nonoperative therapy who underwent combined gluteal tendon reconstruction and bursectomy. [27] The investigators compared the preoperative ultrasound images with surgical findings and found a high positive predictive value for gluteal tendon tears.
