Ankylosis refers to joint immobility. The ball-and-socket joint, formed by the femoral head and the acetabulum, refers to the hip. In this case, the hip joint is ankylosed.

The condition may be congenital, hereditary, or it may be the result of disease, (e.g., arthritis or tuberculosis); trauma, e.g., fractures; surgery, e.g., hip arthrodesis; or contractures due to immobility. Bacterial infection such as staphylococcus and streptococcus may be most common in the pediatric age group.

The signs and symptoms of this condition may begin with arthritis (see Diagnostic Code: 5003 Arthritis, degenerative) and include: stiffness, limited motion, structural changes, and pain. Tuberculosis of the hip (see Diagnostic Code: 6311 Tuberculosis, miliary) will present with pain, effusion, stiffness, and muscle deterioration.

Laboratory tests will be based on the underlying disease or condition. X-rays, computed tomography (CT) scan, and magnetic resonance imaging (MRI) are used for diagnosis in orthopedic conditions. A goniometer is used to measure ranges of hip extension and hip flexion angles.

Arthritic conditions of the hip that may lead to ankylosis are usually treated with joint replacement (see Diagnostic Code: 5054 hip replacement prosthesis)The non-union of the femoral neck after an open reduction for a displaced fracture might be treated with a hip prosthesis. A surgically placed ankylosis might be used to treat osteomyelitis or tuberculosis of the bone.

If a surgical arthrodesis is done, it is crucial to have the right degree of flexion (25 degrees). If the degree of flexion is too great, it would make walking and lying in bed difficult. If arthritic ankylosis and muscle atrophy are to be prevented, physical therapy and rehabilitation are needed.

• At the 90 percent rate, entitled to Special Monthly Compensation (SMC), where there is unfavorable, extremely unfavorable complete ankylosis of the hip, the foot not reaching the ground, crutches necessitated will constitute loss of use of the foot. Loss of use of a foot will be held to exist when no effective function remains other than that which would be equally well served by an amputation stump at the site of election below elbow or knee with use of a suitable prosthetic appliance. The determination will be made on the basis of the actual remaining function, whether the acts of balance, propulsion, etc., in the case of the foot, could be accomplished equally well by an amputation stump with prosthesis. 38 CFR 3.350(a)(2)(i)(a)

• Evaluate under diagnostic codes 5256, 5257, 5260, or 5261 for the knee, or 5250-5254 for the hip, whichever results in the highest evaluation.