Developmental dysplasia of the hip (DDH) is a condition caused by abnormal development of the hip joint that presents mostly in children. DDH describes a variety of conditions in which the ball and socket of the hip do not develop properly. The hip is a ball and socket joint. Normally the top of the thigh bone (femur) has a round ball shape which fits into a cup like socket on the pelvis (acetabulum) 1. Historically, many doctors have called this pathology congenital dysplasia of the hip, or CDH, because they were thinking that the condition is only targeting infants, but later they discovered that it could be acquired after birth. However, both CDH and DDH terminologies are acceptable for medical use. DDH has been known for centuries but the understanding of the pathology was unclear. The ancient Greek physician Hippocrates was one of the first who talked about DDH2. The exact etiology of DDH is unknown, and there are several factors may cause DDH. Genetic factors play an important part in causing DDH. It tends to run in families and in populations such as countries along the northern and eastern Mediterranean seaboard. In pregnant women, hormonal factors may cause some abnormalities for the infants such as an increase in oestrogen, progesterone, and relaxin in the last few weeks of pregnancy these increases may cause ligamentous laxity. Intrauterine malposition is one of the important factors that may cause DDH, such as breech position with extended legs in the uterus. Postnatal factors may have a role in resulting in neonatal instability and acetabular mal development. Some studies showed that both genetic and environmental factors have statistical associations. The reported incidence of neonatal hip instability is 5 â€" 20 per 1000 live births2. However, most of these hips stabilize spontaneously, and on re-examination 3 weeks after birth the incidence of instability is only 1 or 2 per 1000 infants. Girls are much more commonly affected than boys, the ratio being about 7:1. Physical therapy has an important role in DDH in which to restore the movement of the legs and strengthen muscles in the post surgical stage, after being in cast3.
In the intrauterine life around the twelfth week the newly formed hip joint is vulnerable and the joint capsule is defined, but it is not strong and the first major positional change occurs, positioning the lower limb in internal rotation. This position forces the hip joint to function as a pivot point, and the joint must be stable to support the forces involved. During this period, synchronized neuromuscular development must occur to avoid unbalanced forces on the hip joint, which may produce dislocation. If the hip dislocated at this time, the joint will be dislocated until birth2.
The early and the most common signs and symptoms of DDH are2-4:-
The leg may appear shorter on the side of the dislocated hip.
The leg on the side of the dislocated hip may turn outward.
The folds in the skin of the thigh or buttocks may appear uneven compared to the sound side.
The space between the legs may look wider than normal.
The abduction of the dislocated side is limited or restricted compared to the sound side.
DDH is sometimes noted at birth. The newborn specialist screens newborn babies in the hospital for this hip problem before they go home. However, DDH may not be discovered until later evaluations. Your baby's physician makes the diagnosis of DDH with a clinical examination. During the examination, the physician obtains a complete prenatal and birth history of the baby and asks if other family members are known to have DDH4.
The early diagnosis of DDH for infants from birth to 3 months, it may detected by history and physical examination in the first days of the baby life. The Ortolani maneuver test and Barlow test may be carried out to identify hip instability. In walking age above 1 year the patient will develop flattening of the buttock of the dislocated side when patient placed in prone position, and the height of the greater trochanter increased in comparison with the opposite side. As will as during walking child will be limbing to one side, and the abduction and the extension of the hip joint are limited5-6-7. There are several methods to determine the DDH, location of the dislocated hip, and the severity the dislocation. In radiographic examination anterior-posterior view with the pelvis and ASIS flattened and the lower limbs in extension, the Hilgenheiner (Y) and Perkins lines can drown on the X-ray to determine if there is dysplastic, subluxed, or dislocated. The Y line drown to figure out the relationship between femoral head and the acetabulum, and The Perkins line drown to shown the relationship between the proximal femur and the acetabulum. However, the cartilage around the hip joint and femoral head is not visible in radiographic examination. Sonography, it is another common, and useful method used in the analysis of the hip joint, usually it is used for infants below 6 months. The sonography is more accurate than radiography because in sonography the examiner can see the cartilage around the hip joint without expose the infant to ionizing radiation but not all dysplastic hips could be identified with ultrasound. Also, Arthography could be used to diagnose DDH. It is radiographic method utilized to study the hip joint by injecting radiopaque dye. This method is invasive and usually applied under general anesthesia in infants between 3 months to 1 year, and sedation in older children. The Magnetic resonance imaging (MRI) the best way for diagnosis of DDH in advanced than X-ray because we can see inside the body without radiation by using large magnet, radio wave and computer. MRI is performed for infants, but they need to be sedated so they do not move during the examination and the examination may take from 30 to 60 min2. There are several interventions designed to treat DDH. The aim of treatment is to return the femoral head to its normal relation within the acetabulum and maintain this relationship until the abnormal changes reverse. The earlier intervention for DDH the less abnormal changes in the hip joint and less time is needed for the structure to return to their normal relationship. In DDH the interventions different according to the age of the child and the severity of dislocation or subluxation. The DDH has several classifications for treatment, and the more common classification is categorized in to three categories, Birth through 3 Months of Age, 4 Months to Walking Age, and after Walking Age. These three categories will be discussed in detail in this study 2-3-5:-
Treatment of DDH, birth through 3 months of age:
The concept of the treatment based on positioning a reduced hip in flexion and mild abduction will stimulate normal joint development. As well as, the maintenance of the reduction position important issue in the treatment. There are numbers of braces and orthotics available to maintain the hip in flexion and abduction but the more common orthosis is the pavlik harness. The pavlik harness is a dynamic orthosis that position the thighs to allow spontaneous reduction of the hip joint. In pavlik harness the hip should be flexed 90-110 degree and abducted 65 degree to achieve and maintain the reduction.
This orthotic has many advantages such as:
- It is easy to applied and accepted from the parents.
-Does not interfere in child care.
-Adductor muscles are gently stretched by the weight of the legs.
-Active movement is preserved in the safety zone.
Also there are contraindications for the pavlik harness such as:
-Child older than 9 months.
-Femoral head needs more than 110 degree of flexion.
-Other disease processes that limit reduction, such as connective tissue disorders.
-Anterior or inferior dislocation that will not reduced with hip flexion.
Treatment from 4 months to walking:
It may become more difficult in this stage to relocate the femoral head in the acetabulum. In this period traction may be used to relocate the hip followed by the pavlik orthotic. Closed reduction may be required in this period with application of cast which called hip spica cast. The indications of the closed reduction treatment are:
-Dislocated hip when the pavlik harness is inappropriate
-About 3 or more months of age possibly up to 18 months
The operative of the closed reduction usually applied under general anesthesia. The surgeon gently traction the thigh with flexion 90 to 110 degree with abduction 65 degree and, pressure applied over the greater trochanter into the socket by lifting it anteriorly over the posterior edge of the acetabulum. The reduction most be confirmed by AP X-ray or ultrasound. The closed reduction operation must followed by spica cast. The spica cast is applied to immobilize the hips after the close or open reduction. The minimum period of the spica cast is between 8 to 12 weeks for child up to 24 weeks for an older child.
Treatment after walking age:
In some cases the DDH discovered after the child starts walking which is very rare. In some patients closed reduction and casting can be successful, but in many children at this age operative reduction (open reduction) is necessary. When the hip dislocation does not respond to nonoperative treatment (closed reduction), open reduction is important to restore the normal anatomy of the hip joint. In open reduction operation the psoas tendon is divided, obstructing tissues (redundant capsule, thickened ligamentum teres) are removed and the hip is reduced. The hip joint after surgery is stable in 60 degree of flexion, 40 degree abduction, and 20 internal rotation with application of spica cast for 8 to 12 weeks.
Physical Therapy in DDH
Physical therapy assists in the early detection of illness in children and uses a variety of methods for treatment. Pediatric physical therapy perform assessment, proper treatment, and health supervision of infants, children, and adolescents with a variety of developmental, neuromuscular, skeletal, or acquired health disorders8. The goal of physical therapy intervention is to restore all movement of the lower limb and maintain it5-6. Physical therapy intervention begins after the child removed the spica cast because during the cast period the child is immobilized for 8 to 12 weeks, so most of the lower limb muscles are short and very weak2. In the DDH there are specific tests and measurements should be taken during the subjective assessment and objective assessment such as5-7:
1. Subjective assessment:
The first diagnosis date and when it is confirmed.
At what age the child is diagnosed.
What type of treatment patient have got.
Another congenital, neurological, musculoskeletal disorders.
For how long the cast applied for the child.
2. Objective assessment:
- Skeletal alignment.
- Lower limb length in weight bear and non-weight bear.
- ROM of the hip, knee, and ankle.
- Limitation of ROM.
- Lower limb muscle testing.
- Gait pattern if the child walking.
- Balance during standing and walking according to the age.
After the assessment done and the measurement taken the physical therapist must design and write his plan of treatment according to the measurement outcomes.
Plan of Treatment:
Hip joint mobilization.
Therapeutic exercises for hip, knee, and ankle muscles:
Strengthening exercises
Stretching exercises
Functional training as strengthing exercises and home management, including activities of daily living.
Treatment goals:
The physical therapy goals of the treatment in DDH to restore the movements of the lower limb to the normal pattern and gain normal muscle length of hip, knee, ankle muscles .
These are some of the strengthing exercises as functional training, and also the family can learn these exercises to apply them as a home program to accelerate the rehabilitation period9:
1. Pulls to stand
Muscle activity pattern: Concentric contraction of hip flexor, isometric contraction of hip abductor, and concentric contraction of bilateral quadriceps
2. Side step during support on surface
Muscle activity pattern: concentric contraction of swing limb abductors, eccentric contraction of stance limb adductors, isometric co-contraction of hip and knee flexors and extensors, and concentric cont. of planter flexors
3. Controlled lowering with support
Muscle activity pattern: Eccentric gluteal activity, eccentric quadriceps activity, eccentric contraction of planter flexion.
4. Stair climbing with support followed by without support as progression
Muscle activity pattern: Concentric contraction of swing limb hip flexors, concentric contraction of swing foot dorsiflexors, isometric stabilization of stance limb gluteals, concentric contraction of swing limb quadriceps, concentric contraction of stance limb ankle planter flexors, and concentric contraction of swing limb gluteals as increased weight is transferred.
Conclusion:
In conclusion, DDH it is a congenital dislocation of the hip since birth or acquired few weeks after birth, so early examination is needed after birth immediately and regular examination until 3 months to be in safe. As well as, if DDH detected in this period the intervention will be easier to control DDH rather than above 1 year9-10. However, if the child has had successful treatment for DDH, he or she will likely not have any further hip problems. But have parents should examined regularly to make sure his or her hips continue to grow and develop normally. Physical Therapy has essential role in dealing with DDH to restore the function and rehabilitation in post-surgical children after being in spica cast.
