[Hip joint arthrolysis due to heterotopic ossification].

OBJECTIVE

Restoration of joint mobility with preservation of femoral head perfusion and warranty of joint stability. Pain reduction. Enhancement of the autonomous daily mobility (if possible regarding the cognitive status) as well as the ability to sit. For nonambulatory, bedridden patients ease of sanitary tasks and improvement of patients' convenience.

INDICATIONS

Joint stiffness with limitation of the quality of life. Pain. Joint deformity, especially in cases of progressive subluxation.

CONTRAINDICATIONS

Relative: radiologically and scintigraphically immature heterotopic ossification (HO) with moderate limitation of motion and patients who are not able to tolerate the demanding postoperative management.

SURGICAL TECHNIQUE

The patient is positioned depending on size and location of ectopic bone. Ectopic bone is released from surrounding soft tissue or by making use of a gap between original bone and ectopic bone from the femur or pelvis. If ectopic bone is close to neurovascular structures, these have to be identified and protected.

POSTOPERATIVE MANAGEMENT

Postoperative irradiation in patients > 50 years. Generally, medicamentous prevention for recurrent cases with nonsteroidal anti-inflammatory drugs. Intensive and aggressive physical therapy, especially in patients with neurologic disorders. Depending on the extent of arthrolysis and the cause of HO, full, partial, or no weight bearing of the extremity over the first 6 postoperative weeks.

RESULTS

The literature does not allow to draw firm conclusions regarding the occurrence of HO. The incidence of HO after primary total hip arthroplasty is estimated at 42%. In 9% of these cases, a severe HO with major limitation of motion or ankylosis occurs. In patients with neurologic injuries (brain injuries, spinal cord injuries) the incidence varies between 20-40%, but only one third of these patients show limited function or ankylosis. After surgical arthrolysis, the recurrence rate amounts to 25-30% at a mean follow-up of 6 years.