LCPD usually affects children between the ages of 6-10 and is a condition in which the femoral head (hip) looses its blood supply and then slowly re-vascularizes over the next 2-4 years. As the hip dies, the femoral head collapses causing stiffness and contractures of the muscles around the hip which can lead to subluxation.
The main principles of treatment include maintaining motion of the hip and containing the femoral head inside the acetabulum. If the femoral head stays insides the acetabulum then it will re-shape over time and stay rounder. If the hip starts to come out of the socket (subluxation) it will more likely deform and stay deformed thereby causing pain and premature arthritis later in life.
Articulated hip distraction along with a small diameter decompression (to help create new vascular channels to the femoral head) is a procedure which addresses many of the principles of treatment of LCPD.
The articulated external fixator is used to help reposition the femur in the hip joint (i.e. containment). It is articulated to maintain hip motion thereby allowing synovial circulation. The external fixator is then used to gradual distract the femur from the acetabulum to minimize mechanical stresses on the hip joint. This prevents further collapse and allows the femoral head to re-grow.
Similar treatment strategies apply for Juvenile AVN of the hip and articulated hip distraction can be considered in certain cases
Hip chondrolysis is a rare condition that usually affects adolescents, in which there is progressive and rapid destruction of the cartilage in the hip joint. Articulated hip distraction can be considered among the treatment options for this disorder.
AP and lateral X-rays to assess proximal and lateral femoral head migration within the hip joint.
- The patient is placed on the table in a supine position (on his back).
- The affected side is placed at the edge of a radiolucent table, and the affected leg is positioned in abduction and extension on a padded stand.
- A skin incision is performed in order to release the adductors. If the patient has a fixed hip flexion contracture, the patient undergoes an anterior release as well.
- A 1.5mm wire is inserted up the femoral neck and into the center of the avascular lesion in order to perform a small diameter core decompression of the necrotic zone of the femoral head.
- A cannulated 3.2-mm drill is used to create a small-diameter bone channel into the necrotic bone.
- Following this, a hip arthrogram is performed. (A liquid dye placed into the hip to allow visualisation of the cartilage of the femoral head.)
- The affected leg is then placed into full extension and at least 25 to 30 degrees of abduction. Containment of the femoral head is confirmed on fluoroscopy.
- An articulated monolateral hip distractor external fixation system is then applied to the hip in this position. When the frame application is complete, the hinge point is verified by flexing and extending the hip joint under fluoroscopy. The hip joint is acutely distracted 3 to 5 mm.
- Patient is then returned to the recovery room.
The patient is asked to distract the hip joint 0.5 mm a day for 14 days.
Daily hip exercises are required in order to maintain hip motion in flexion and extension with the articulated joint of the fixator.
The patient is allowed to have free hip flexion or extension during the day but is maintained in full hip extension at night with a removable hip extension blocking bar connected between the proximal (pelvis) and distal (femoral) portions of the external fixation device.
X-rays are taken 14 days postoperatively to ensure a distraction of at least 5 mm as well as adequate abduction of the affected leg. After distraction of the hip joint is completed, daily home exercises are performed and physiotherapy is reduced to 1-2 sessions per week.
The patients are allowed to toe touch weight bear with a walker.
Removal of the frame
The frame is removed following a 4-month period and a second arthrogram (dye in the hip) is performed under anesthesia.
After frame removal, the patient is permitted to fully weight bear but is placed in a pre-moulded custom-made hip abduction brace for full-time use for one month, followed by night-time wear for 3 months. During the initial post-removal-period, it is essential for the patient to be seen by a physiotherapist in order to get an exercise protocol required to regain all hip motion while maintaining hip extension and abduction. Regaining hip motion is fundamental to the treatment and will be constantly reinforced to both the family and the patient.
- Loss of hip joint mobility and strength
- Fracture of femur or hip
- Nerve injury to the sciatic nerve (Neuropraxia)
- Infection of bone (osteomyelitis)
- Neurovascular (very rare)
For a complete list of the risks and complications, please see Risk and Complications acute deformity correction tab.