Dysplasia in the Skeletally Mature Patient

Key Points

Hip dysplasia commonly presents in adolescent and young adult patients with no known history of hip disease.
Early diagnosis is essential to provide the opportunity for optimal hip preservation treatments.
History, examination, and plain radiographs are the essential components of the diagnostic workup.
Multiple hip preservation surgical treatments can be considered for the treatment of symptomatic hip dysplasia before established secondary osteoarthritis, yet acetabular reorientation is the most appropriate surgical intervention in most cases.
Hip dysplasia with advanced secondary osteoarthritis should be managed with total hip arthroplasty when nonoperative management has failed.

Instability secondary to hip dysplasia frequently does not become symptomatic until skeletal maturity. A history of previous treatment may be reported, such as closed reduction with an orthosis or a spica cast as an infant or young child; more often, no history of previous awareness or treatment of hip dysplasia is noted. Once an unstable hip has become symptomatic in the skeletally mature patient, surgical correction of existing acetabular dysplasia is necessary to arrest progressive pathologic processes.

Differential Diagnosis

Patients presenting with hip pain can be classified into many different categories. One early distinction is the site of the pain. Lateral hip pain often can be caused by a trochanteric bursitis, which can be related to abductor dysfunction. Low back pain or radiculopathy can also be present or can manifest as lateral hip pain. Most intraarticular hip pathology presents as groin pain. Patients with limited range of motion and pain may suffer from impingement about the hip with a femoral-sided cam lesion, an acetabular-sided pincer lesion, or both. They tend to report pain with sitting in low chairs or in a car for an extended period of time. Patients with hip dysplasia (and no impingement) typically exhibit a normal range of motion. They describe pain more with activities such as walking or running. Patients with either condition may experience labral tears and may have mechanical symptoms. Certainly, other causes of adult hip pain are known, such as infection (septic arthritis or osteomyelitis), tumor, metabolic disease, avascular necrosis, trauma, or general osteoarthritis independent of hip dysplasia. After a careful history and physical examination are performed, diagnostic imaging with plain radiographs is the next step in narrowing a differential diagnosis for hip pain in the adult.

Clinical Findings

History

Skeletally mature patients with symptomatic clinical instability secondary to hip dysplasia present with a history of variable hip pain and/or limp. This pain can be localized to various areas about the hip, but primarily is reported as groin pain. The pain can be rather insidious, persisting for months to years before presentation. The pain is often accentuated with activity. A fatigue limp is often present. With this presentation, the pain initially may be localized to the hip abductors and/or the greater trochanter. This is attributed to lateralization of the hip center and increased load on the hip abductors. An individual patient's level of activity will often determine how early in life they develop symptoms, because increased activity places an increased demand on the hip for any given degree of dysplasia. Mechanical symptoms such as catching, locking, or popping can accompany the activity related hip pain, suggesting labral pathology or a chondral flap.

The level and character of pain, as well as its duration and associated symptoms, should be outlined; this feature can help in diagnosis and can guide treatment. Questions pertinent to hip joint function in daily activities used to calculate the Harris Hip Score are helpful for preoperative evaluation and can be used to assess the efficacy of treatment. Although typically used to evaluate the outcomes of hip arthroplasty, this scoring system has also been used to assess hip preservation . Patients in studies of adult hip dysplasia treated with hip preservation techniques have preoperative scores that vary between 50 and 65 on a 100-point scale. If the patient was treated as a child for hip dysplasia, a detailed history of childhood treatment, both nonsurgical and surgical, must be obtained.

More recently, several validated patient-reported outcome measures have been developed to help better characterize both the preoperative level of pain and function, as well as the response to surgical and nonsurgical treatment. The newest is the Patient Reported Outcomes Measurement Information System (PROMIS), which is sponsored by the National Institutes of Health. Prior studies have demonstrated a negative impact of femoroacetabular impingement on PROMIS scores, and research suggests that the use of PROMIS scores may prove to be a valuable tool for measuring clinically important response to surgical treatment.

Physical Examination

The first step in examining a painful hip is to evaluate the patient's gait. Patients can present with an antalgic or a Trendelenburg gait. Patients with an antalgic gait may have significant labral pathology, causing more acute pain or more involved degenerative changes from years of lateral point loading. Those with a Trendelenburg gait are exhibiting manifestations of a lateralized joint center and abductor weakness. If the hip joint is functionally unstable, the single-leg stance Trendelenburg test will be positive. Sometimes it is necessary to have the patient perform the test for several seconds. Occasionally, the patient will note reproduction of trochanteric hip pain while performing the Trendelenburg test.

Next, active and passive range of motion is evaluated, coupled with an assessment of motor strength in the hip flexors, extensors, adductors, and abductors. Patients with classic acetabular dysplasia may have a normal or excessive passive range of motion. Affected patients commonly have a positive impingement sign owing to the associated acetabular rim disease.

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