New Hip Orthosis to Prevent Dislocation

Adult hip orthoses have been used for decades to stabilize the hip after a dislocation or to prevent dislocation after extensive hip revision surgery. Typically a hip orthosis is comprised of a thermoplastic pelvic and thigh component, joined by a hip joint with adjustable coronal and sagittal plane range of motion. Recently, orthopedists have questioned the efficacy of hip abduction orthoses (1), and many orthotists have reported a reduction in referrals. Physicians who previously used orthoses after all their hip revision surgeries may now only order them for their most extensive cases, or when a patient has already dislocated. Recent advances in minimally invasive surgery for the hip have influenced hip management protocols, in addition to physician concerns about patient comfort and compliance. Patients frequently report that the orthoses are clumsy and uncomfortable, and elderly and frail patients often have poor tolerance for the rigid plastic systems sometimes worn in bed. The trend toward performing hip replacement surgery on younger, more active patients challenges orthotists to create an orthosis that provides protection without interfering with work and activities. A hip orthosis was designed to address patient comfort concerns in order to increase the likelihood of compliance, and provide protection against dislocation. ¹

The pelvic component is fabricated from a synthetic webbed material reinforced with plastic to add structural stability and strategic support for the hip joint. This less rigid pelvic interface provides comfortable suspension of the orthosis and patient controlled compression. The thigh cuff is also made from plastic-reinforced webbing, and has adequate clearance inferior to the groin and posterior to the knee to prevent impingement. The orthosis is well tolerated by patients, fits under clothing, and provides protection against dislocation when a more rigid system is contraindicated.¹

There are many indications for hip orthoses, and the orthotist must ensure that the orthosis is set to protect the hip at risk. In general, to prevent posterior dislocation, the hip flexion angle is set to stop forward flexion at seventy degrees. The abduction stop is set in ten to fifteen degrees of abduction, and no extension stop is used. To prevent anterior dislocation, the sagittal plane motion is set between thirty and seventy degrees of flexion to block out extension, one of the primary mechanisms of dislocation. A knee ankle foot orthosis (KAFO) is added to provide rotational control. When a KAFO is attached, the knee and ankle range of motion is free and the coronal plane alignment of the hip is neutral. (2)

¹The California Hip Orthosis, Orthomerica Products, Inc.

References

1. DeWal H, Maurer SL, Tsai P, Su E, Hiebert R, Di Cesare PE. "Efficacy of Abduction Bracing in the Management of Total Hip Arthroplasty Dislocation". J of Arthroplasty. 19:6. 2004.

2. Lima D, Magnus R, Paproksy R. "Team Management of Hip Revision Patients using a Post- Op Hip Orthosis". 6:1. 20-24. 2004.