Patient Information: Perthes disease
What is perthes disease?
Perthes disease is a disease of the hip in which the bone in the hip joint loses its blood supply. This may cause the bone (femur) to change shape so that it no longer fits into the hip joint (femoral head) properly. The disease run a 2-year course, and if left untreated, can cause permanent damage to the bone.
The first stages of perthes disease are silent. This means that the patient dose not limp or complain of pain. The bone in the hip joint (top of the thigh bone or femoral head) loses its blood supply and that part of bone subsequently dies. The bone weakens and a small fracture develops, with the result that the femur head begins to flatten. Circulation returns to the head of the femur within months, rejuvenating the bone but causing pain and a limp (and a visit to the doctor). If left untreated, the femoral head may flatten over the course of months. Leading to arthritis in later years.
What cause perthes disease?
The cause of perthes disease remains unknown. It is, however, an accepted fact that it results from the head of thigh bone. Many reasons have been proposed for this lack of circulation, but none have been confirmed.
Signs and symptoms of perthes disease?
Patients with perthes disease present with a limp, pain, and a stiff hip. When the range of motion at the hip is tested, some movements will be reduced. “Doing the splits” is the first movement in which tightening up is noticed. The thigh often gets thin as well.
Some facts about perthes disease
- Perthes disease is found in children between 4 and 10 years of age.
- It affects four times as many boys as girls.
- Twenty percent of cases are familial.(The incidence of the disease is 1:35 in family members compared with 1:20,000 in the general population.)
- The disease affects both hips in 20% of patients.
- The low birth weight (especially boys less than 5.5 pounds) is correlated with the disease
How is perthes detected?
Because many disease processes have signs and symptoms similar to those of perthes disease, it is diagnosed by x-rays. The first x-ray may not be helpful. Because characteristic signs may not have appeared. Bone scans and magnetic resonance images (MRI’s) can be used to detect the amount of blood circulation in the femoral head. A two-group classification for perthes has been developed. Group A consists hips with less than half of the femoral head involved. This group generally needs little treatment and recovers well. Group B includes hips with more than half of the femoral head involved. Patients in this group need treatment to do well.
What treatment is available for perthes disease?
The aim of treatment is to prevent flattening of the femoral head. There are several methods of treatment: bracing, short periods of rest, soft- tissue releases, and operations on the bone. The choice depends on factors such as the severity of the problem and the stage of the disease.
Treatment is divided into five categories: (1) observation, (2) intermittent symptomatic treatment, (3) definitive early treatment (to prevent deformity), (4) surgery to make the femur head round again, and (5) late surgery for arthritis.
Observation consists of testing the hip stiffness and taking x-ray every few months. It is suitable for children at the time of onset of perthes disease, regardless of the amount of femoral head involvement, provided there is no limitation of movement or subluxation (partial dislocation) of the hip. Observation is also appropriate for children who have Group A perthes with a good range of hip motion and no evidence of femoral head collapse (as indicated by x-rays).
Intermittent symptomatic treatment
This treatment consists of rest and exercise when the hip hurts, and may be used in conjunction with observation. It includes muscle-stretching exercise to maintain the joint’s range of motion, and periodic bed rest, with or without traction. X-rays at 3-4 month intervals are necessary during the early months after the first signs and symptoms appear.
Definitive early treatment
This type of treatment is used in cases of clinical onset at 6 years of age or older, a Group B hip, and loss of femoral head containment. It involves the use of containment methods (either surgical or non-surgical) early in the disease process. Containment can be pictured as an ice cream scoop encasing soft ice cream. When the ice cream is enveloped by the scoop (like the head of the femur in the acetabulum or hip socket), the ice cream remains round and undented. Uncontainment occurs when the scoop covers only half of the ice cream. The ice cream outside the scoop dents and the remainder then seeps out. Similarly, the femur is no longer within the acetabulum or socket and a dent develops so the femur is not rounded.
A. Nonsurgical containment (braces and casts)
This type of containment is carried out by abducting or drawing away from the body the affected limb in order to place the femoral head back into the acetabulum. The joint is allowed to move, and the movement gradually molds the head into a round shape. Casts and/or braces may be used to keep the femoral head within the joint, and crutches may be used to limit weight bearing on the joint. Abduction casts consist of long leg casts applied to both lower limbs and held apart by sticks.
A variety of abduction apparatuses and braces are also available. They are lighter, removable, less cumber-some, but also more expensive than casts. Twelve to 18 months of this type of treatment may be required.
B. Surgical containment
Surgical containment is indicated when nonsurgical treatment is not feasible or when it is not possible to contain the femoral head in the acetabulum (hip joint) in an abducted position.
A procedure known as an innominate osteotomy is performed. It takes about 2 hours. The purpose of this operation is to use the normal movement of the hip to mold the soft bone into a round shape.
The bones are moved into the desired position and held together with pins. The pins are removed after 6-12 weeks in a minor operation, usually done on an outpatient basis. After surgery the child is often put into a cast or brace until the joint is stable (i.e., the femoral head well contained). After an 8-week postoperative recovery and a short rehabilitation period, the child is able to resume normal activities. The entire process usually takes about 3-4 months.
Making the head round again
When there is significant femoral head deformity that cannot be successfully treated with the methods already described, alternative techniques must be sought.
One procedure used is known as a muscle release (of adductors, muscles that draw the limb in toward the centre of the body).this is followed by the use of an abduction cast to hold the limb out. After the patient has worn the cast 3-4 months, enough abduction should be gained so that the femoral head can be placed into the acetabulum through a surgical osteotomy.
A second technique involves a combination of femoral and pelvic osteotomies. If the deformed femoral head cannot be contained within the acetabulum, part of the head may have to be removed.
Late surgery for arthritis
Late surgery is rarely necessary in adults who have had perthes disease as children. Arthritis is usually managed by either an osteotomy to realign the joint or prosthetic replacement of the joint. The method chosen depend on the age of patient.
In general, the younger the child at the age of onset of perthes disease, the better the results of treatment. Many long-term studies have shown that most children with clinical onset at less than 6 years of age have an excellent prognosis. However, they must be evaluated through clinical and radiological (x-ray) examinations at intervals of 2 to 4 months. If loss of either motion or containment is noted, a short course (3-6 months) of nonsurgical treatment may be necessary.
The extent of femoral head involvement has much to do with prognosis. Children with less than half of the femoral head involved (Group A) show better treatment results. As loss of containment may still occur, these children must also be examined every 2-4 months.
In girls, perthes disease is more likely to involve over half of the femoral head, and so more vigorous treatment is usually needed. Regardless of the method of treatment chosen, it is essential that a good range of motion be achieved for the hip and maintained throughout treatment. The outcome should then be satisfactory.
Tips for parents
- Don’t panic! Many surgical and treatment advances have been made in this field. Doctors who treat this condition are familiar with its details and have repeatedly demonstrated high levels of success in treating it.
- Ask questions. You should discuss your child’s problem thoroughly with your doctor. Do not hesitate to ask him all the questions you may have. Write down questions ahead of time.
- Become involved in your child’s treatment. We will teach you what you need to know to help in your child’s recovery.
- Follow directions about casting, braces and harnesses carefully. Remove them only as directed by the physician.
- If your child is in a cast or brace, keep it clean.
- Continue to monitor your child’s problem with your physician. This will allow for early detection and treatment should the condition recur.
- Make a conscious effort to treat your child as normally as possible.
- Encourage your child to resume normal activities as soon as is medically recommended.
- Use all available resources. Remember you are not in this alone. Many professionals are available to answer questions or direct you to people who can help you.