Definition

Adhesive capsulitis of the hip joint is a condition of unknown etiology characterized by the gradual loss of passive and active hip motion, which is a result of retraction of the fibrous joint capsule.

Lequesne and colleagues classified adhesive capsulitis into primary and secondary forms. Primary adhesive capsulitis is characterized by idiopathic, progressive, and painful loss of both active and passive range of motion. Secondary adhesive capsulitis results from known intrinsic or extrinsic causes. Hannafin reported that secondary adhesive capsulitis has a histopathologic appearance similar to that of primary adhesive capsulitis but can be associated with any one of multiple medical conditions ( Table 52.1 ).

The hip joint is functionally and structurally complex, consisting of the femoral articulation, acetabulum, supporting soft tissue, muscles, and cartilaginous structures ( Fig. 52.1 ). It is a multiaxial synovial ball-and-socket joint.

Hip joint. Normal anatomy and fibrous capsule.

The femoral articulation forms roughly two-thirds of a sphere, approximately 40% of which is covered by the acetabulum. Articular (hyaline) cartilage covers the femoral articulation except at the fovea capitis, a depression on the central surface.

The acetabulum is formed by fusion of the ilium, ischium, and pubis. It is hemispheric in shape and projects anterolaterally and inferiorly. The lunate surface is the articular portion, and the nonarticular portion constitutes the floor (acetabular fossa). The acetabular fossa (covered by synovium) is continuous with the acetabular notch, which lies between the ends of the lunate surface. The acetabular fossa lies in the inferomedial portion, close to the ligamentum teres (round ligament), which attaches to the fovea capitis. The depth of the acetabulum is increased by the dense fibrocartilaginous labrum, which attaches to the rim of the acetabulum, except at the acetabular notch.

The transverse ligament bridges the acetabular notch and in combination with the acetabular labrum forms a complete ring around the acetabulum. It converts the acetabular notch into a foramen, through which the intra-articular vessels pass to supply the head of the femur.

The fibrous capsule of the hip joint attaches to the labrum to form a circular recess, which encloses the joint and most of the femoral neck (see Fig. 52.1 ). Medially it attaches to the base of the acetabulum and extends to the innominate. Inferiorly it attaches to the transverse acetabular ligament. Laterally it attaches to the femur anteriorly and extends along the intertrochanteric line and along the femoral neck posteriorly and inferiorly. The fibrous capsule is reinforced by the pubofemoral, ischiofemoral, and iliofemoral ligaments, which are considered thickening of the fibrous capsule and help stabilize the hip joint. The capsular fiber consists of both superficial bands and deep bands. The deep circular bands from the iliofemoral ligament form the zona orbicularis, which divides the synovial cavity into medial and lateral recesses. The hip joint is dynamically stabilized by numerous muscles.

Neviaser introduced the term adhesive capsulitis and described pathologic changes in the synovium and subsynovium. Evidence supports the hypothesis that the underlying pathologic process involves synovial inflammation with reactive capsular fibrosis, thus making adhesive capsulitis both an inflammatory and a fibrosing condition.

The histologic changes of adhesive capsulitis seen in the hip are similar to those in the shoulder. There is chronic inflammatory reaction in the capsule and synovium with subsequent adherence to the femoral neck. Biopsy tissue shows evidence of edematous, fibrotic synovial tissue with partial or complete loss of synovial lining.

Many authors acknowledge that adhesive capsulitis is a relatively common clinical syndrome when it occurs in the shoulders (2% to 5% of the general population) but is infrequently described in other joints, such as the wrist, hip, and ankles.

Symptoms

The diagnosis of hip adhesive capsulitis is based on clinical findings of decreased passive and active range of motion in all planes of the hip joint, with no abnormal radiographic findings. The patient may describe gradual onset of stiffness with hip movements, resulting in difficulty in crossing the leg or sitting in certain positions. Patients may describe difficulty with lower extremity dressing, such as putting on socks, or with hygiene, such as clipping of toenails.

Pain is usually a presenting symptom, especially with extreme external rotation or abduction, and is usually the reason for seeking medical evaluation. Gait difficulty may or may not be present, but it is usually not to the severity that a gait aid is required.

The diagnosis of hip adhesive capsulitis is rarely made, possibly because the hip joint can sustain range of motion loss without significant disability, whereas even a mild loss of motion in the shoulders can result in significant difficulty with performance of routine activities of daily living.

Physical Examination

Hip pain can be caused by different intra-articular and extra-articular structures. Differentiating the specific pathologic structures can be challenging, but it is critical for appropriate medical management. The history, physical examination, and adjuvant imaging are crucial in identifying the source of pain. In patients with adhesive capsulitis of the hip, the clinical examination findings may be minimal. The patient may or may not exhibit an antalgic gait pattern. The neuromuscular and neurovascular examination findings are usually unremarkable. The back examination is usually benign, unless there is a concomitant spinal condition. Provocative maneuvers of the hip joint (i.e., Stinchfield and FABERE tests) may generate nonspecific groin discomfort. The hallmark finding on physical examination is limitation of range of motion of the hip joint in all planes (flexion-extension, internal and external rotation, and abduction-adduction).