Dysplasia is a condition or medical term that describes incomplete or partially formed tissue. As it relates to the hip and lower extremity, there are multiple locations for dysplasia to occur. In this section, we will address hip dysplasia, specifically of the acetabular socket and upper femur or proximal femur. Other areas of dysplasia in the lower extremity can occur in rotational dysplasia of the femur, as well as the distal or lower end of the thigh bone, as well as in the kneecap or patella femoral joint. Please view the knee conditions and treatments for further information regarding this.
Acetabular Hip Dysplasia
In this case of acetabular hip dysplasia, the socket itself is not fully formed. This results in a shallow socket that is angled such that the ball is not completely centered or located within the hip or acetabular socket.
This condition is commonly diagnosed early on after birth in the infant years and can be diagnosed with differential leg lengths, restricted range of motion on the dislocated hip, as well as increased skin folds of fat on the thigh or buttocks that appear uneven. These often can be diagnosed in utero or before the baby is born using ultrasound and confirmed on ultrasound once the baby is born. Initial treatments for socket dysplasia work on a technique called pavlik harness, which maintains the hip reduced. In older children and young adults, subtle dysplasia or undiagnosed dysplasia may be a cause of hip pain. It’s important to understand the dysplasia itself does not cause pain, but puts patients at risk of injuring structures that will cause pain, such as the cartilage, ligaments or labrum.
The signs and symptoms vary by age group. In small children and infants, you’ll notice one leg is longer than the other. The one hip may be more stiff and if the child is able to walk, they often walk with a limp. In teenagers and young adults, they may have a painful limp but their leg lengths may be symmetric, but they will often develop pain that can be the result of cartilage damage, osteoarthritis or hip labrum tear. This pain is often located in the groin and in some cases, patients may report feelings of the hip being unstable or dislocating.
Most common cause of acetabular dysplasia is developmental, which the socket does not fully form around the femoral head or ball. Risk factors for this include being the first child, being a relatively large baby, breech presentation, as well as family history. It’s also more common in girls than boys. Other causes include iatrogenic dysplasia, which can result after overaggressive resection of the acetabulum during hip arthroscopy or hip surgery.
The diagnosis is most classically performed using an x-ray screening. If there are signs of dysplasia on the x-ray, your doctor may order a study such as an MRI or CT scan. The CT scan can develop a three dimensional display of your pelvic bone, as well as obtain appropriate measurements to better understand the amount of hip dysplasia you may have.
In infants and small children, pavlik harness or spica cast can be used to keep the femoral head within the socket and help develop a normal socket. Patients who are treated in this manner often do not have issues later on in life and have a normal hip.
Adolescents & Adults
In older children and young adults, a hip or periacetabular osteotomy may need to be performed to help reposition the socket within the pelvis and give a normally functioning hip. In some cases where too much osteoarthritis has developed prior to diagnosis or treatment, a hip replacement surgery may be an option.
There are numerous causes of femoral dysplasia. For instance, there can be rotational dysplasia in which the rotation of the femur in the relationship of the hip and knee joint is such that the hip can be rotated too far in one direction. There can also be angular dysplasia, in which the neck of the femur can be too high or too low, therefore causing issues with the mechanics of the hip joint. These dysplasias can put the soft tissues, such as the labrum and cartilage at further increased risk of causing pain.
Signs and Symptoms
Rotational dysplasia is often noted that patients walk with an atypical gait in which the foot would either need to be overly rotated out or overly rotated inward. Rotational dysplasias can often result in snapping of the hip, both at the groin or in the buttock region. Oftentimes, rotational dysplasia may result in extreme range of motions in rotation of the hip joint. Angular dysplasia is often asymptomatic, but may need to be addressed if the patient is proceeding with other surgeries.
Nonsurgical treatment may include physical therapy to work on gait correction, hip strengthening and balance. Nonsteroidal anti-inflammatories can be used to help manage pain and discomfort.
In some surgical treatment, rotational osteotomy may need to be performed, in which the femur bone is cut and rotated and then held in place until it is healed. Correction of angular deformities can be done similarity but requires a rigid bone to be removed from the femur to change the angle of the femoral neck. Once this osteotomy has been performed, the two parts are plated and screwed together to allow for healing.
Often these osteotomies do not increase the routine healing that needs to occur after surgery.
Over rotation or under rotation may occur. Lack of healing may occur at the location of the osteotomy. More commonly, pain at the site of the hardware, which might require further surgery to remove the hardware.