Hip replacement in adults who had Perthes disease as a child is technically challenging and difficult but entirely possible and with good results. That’s the report from Italian orthopedic surgeons on 32 hip replacements.
Legg-Calvé-Perthes disease (Perthes) is a rare disease that most often affects boys between the ages of 2 and 12. Girls can have LPD. The hips are the main problem. Sometimes both hips are involved, but usually only one side is affected.
With Perthes, blood flow to the ball of the hip is stopped and bone death (necrosis occurs. As necrosis spreads, the ball develops a fracture of the supporting bone. This fracture signals the beginning of bone reabsorption by the body. As bone is slowly absorbed, the body tries to replace it with new tissue and bone.
Degenerative osteoarthritis can occur with age in adults with Perthes. It seems to depend on two things. If the ball reshapes itself and fits into the socket, arthritis is usually not a concern. If the ball does not reshape well, but the socket’s shape still conforms to the ball, mild arthritis occurs in later adulthood. A flattened ball and shallow socket create the most significant problems later.
These patients may need a joint replacement before the age of 50. In this study, the average age at the time of the hip replacement was 37.8 years. Patients included were as young as 19 up to 65 years old.
Total hip replacement is a challenge for these patients because of the odd shape of the hip and leg length differences. The surgeon must work around multiple different deformities affecting the femoral head and hip socket.
Changes in the bone and soft tissues around the hip as a result of previous surgeries can also be a problem. Disruption of bone growth often results in a short femoral neck. Scar tissue can pose some technical pitfalls.
Muscle and tendon surgical releases and bone osteotomies (pelvic or femoral) performed during childhood further alter hip alignment. An osteotomy is the removal of a wedge- or pie-shaped piece of bone in order to shift the position or angle of the bone. It helps in the short-term but can make hip replacement later more difficult and sometimes impossible.
Previous studies comparing adults with hip osteoarthritis but without a childhood history of Perthes to patients with hip osteoarthritis and a positive history of Perthes have been done. Results show that the final outcomes are better in patients without a history of Perthes.
But that has not kept surgeons from trying to improve the procedure for patients with Pethes who develop secondary hip osteoarthritis. With some creative modifications (aligning femoral stems and placing cups on the socket side at just the right angle), it is possible to restore good hip biomechanics.
The authors share their tips and techniques for getting just the right type and size of implant and using special surgical techniques. They point out special considerations the surgeon should watch for (e.g., excess bone that needs trimming, bony overhang after cup placement).
Their success rate is impressive with 96.9 per cent implant survival after 15 years and an overall complication rate of 12.5 per cent. Test scores for hip function were much improved from before to after surgery.
Most of the complications occurred as a result of the procedure itself. There were two patients who developed permanent sciatic nerve palsy when the involved limb was lengthened surgically. One patient had a hematoma (pocket of blood) that had to be drained surgically. And the femur (thigh bone) fractured in one other patient as the implant stem was being placed down inside the bone.
The authors conclude that hip replacement in adults who had Perthes disease as a child is possible. That’s good news for those who develop severe, disabling hip arthritis in their early adult years.
As this study shows, it requires experience and expertise on the part of the surgeon to perform this procedure under these circumstances. Much preoperative planning goes into a procedure like this. Careful examination of the patient and evaluation of imaging studies (X-rays and CT scans) is required. Patients face some risks of complications but if the people in this study are any indication, most will be satisfied with the reduced hip pain and improved hip function.