Approach to hip pain: Clinical sciences

Hip pain is a common presentation in the primary care setting. It’s important to first identify if your patient’s hip pain is due to trauma or infection. Other possible types of hip pain are assessed based on anatomic location and include either anterior, lateral, or posterior hip pain.

If your patient presents with hip pain, start with a focused history and physical examination. Patients report pain in the hip, while the exam might reveal edema, erythema, warmth, hip tenderness, gait abnormalities, and limited joint range of motion.

Your next step is to assess for trauma. This includes an obvious mechanism of injury, like a motor vehicle collision or sports injury, or if there’s a joint deformity or ligamentous laxity.

If trauma is present, think fracture, dislocation, or labral tear. Patients with fractures or dislocations are likely older and may have osteoporosis. Physical exam reveals an inability to walk on the affected limb and a shortened externally rotated abducted leg. With these findings, consider fracture or dislocation and obtain a hip x-ray. If it shows a fracture or dislocation, that’s your diagnosis.

Now, patients with labral tears are typically young athletic adults with abrupt onset of pain that might be from a sports injury or repetitive motion. They may also report a popping, catching, or clicking sound.

Exam typically reveals a positive FADIR test which is when you reproduce pain in the groin when performing flexion, adduction, and internal rotation of the hip. They might also have a positive FABER test which is when you elicit hip pain with hip flexion, abduction, and external rotation. With these findings, consider a labral tear and obtain a hip MRI. If it shows a defect of the labrum, diagnose a labral tear.

On the other hand, if trauma is not present, assess for signs of infection like fever, chills, myalgias, and localized tenderness. If signs of infections are present, your patient may report difficulty moving their hip joint due to pain and swelling. Physical exam will reveal warmth, erythema, and tenderness to palpation over the hip as well as limited and painful range of motion.

Based on these findings, consider septic arthritis and aspirate synovial fluid for analysis of cell count and differential, gram stain, culture, and the presence of crystals. If the synovial fluid has a cloudy or purulent appearance, a white blood cell count of 50,000 or more, the gram stain and culture are positive for bacteria, and the sample is negative for crystals, diagnose septic arthritis.

Here’s a clinical pearl! Hip ultrasound and MRI are not necessary for diagnosis but might help with the evaluation and management of septic arthritis. Ultrasound determines the size and location of joint effusion and is often used to guide optimal needle placement for joint aspiration, while MRI helps characterize the effusion and identify inflammation of surrounding structures.

Alright, if there are no signs of infection, assess the location of the pain. If the pain is in the anterior hip, assess the underlying cause. Let’s start with hip flexor tendonitis. History typically reveals overuse activity of hip flexors which is common in high-intensity sports requiring repetitive motion at the hip, like running or cycling. In some cases, your patient might describe a clicking or snapping over the hip.

On exam, there is pain with hip flexion, especially against resistance, and tenderness to palpation over the anterior superior iliac spine, or ASIS, the anterior inferior iliac spine, or AIIS, or the pubic symphysis. With these findings, diagnose hip flexor tendonitis.

Next up is femoroacetabular impingement. These patients report a gradual onset of pain exacerbated by flexion and internal rotation, while physical exam reveals positive FADIR and FABER tests. In this case, consider femoroacetabular impingement and obtain hip and pelvis x-rays.

Imaging will reveal a cam deformity, which is an abnormal bony prominence at the junction of the femoral head and neck, and a pincer deformity, which involves excessive bony overcoverage of the acetabulum over the femoral head. With these findings, diagnose femoroacetabular impingement.

Here's a clinical pearl! Pediatric hip disorders including slipped capital femoral epiphysis, developmental dysplasia, and Legg-Calvé-Perthes disease can result in bony changes in the femur and acetabulum that contribute to the development of femoroacetabular impingement.

Moving on to osteoarthritis. Your patient is typically older and reports gradual onset of pain with prolonged weight bearing. Exam reveals an antalgic gait, pain with flexion and rotation, and limited range of motion. With these findings, consider osteoarthritis and obtain hip and pelvis x-rays. If imaging shows joint space narrowing, osteophyte formation, and subchondral sclerosis, that’s osteoarthritis.

Let’s go back a step. If your patient’s hip pain is localized to the lateral hip, then assess the underlying cause. First up is meralgia paresthetica, which occurs when the lateral femoral cutaneous nerve is impinged at or near its point of passage through the inguinal ligament.

History might reveal burning or numbness of the upper lateral thigh worsened with prolonged hip extension including walking and standing. Patients might also report wearing tight-fitting clothes around the waist, recent trauma to the hip region, weight gain, or pregnancy.