The hip joint is a ball and socket joint in which the ball of the thigh bone (femur head) articulates with the socket of the pelvis bone. In children, the ball (femur head) is connected to the rest of the thigh bone by a bridge of cartilage called growth plate. The growth of bone occurs at the growth plate (Figure 1).
Slipped Capital Femoral Epiphysis (SCFE) is condition in adolescents, in which the growth plate is weakened. Due to this, the ball (femoral head) gradually slips in a downward and backward direction on weight bearing. You can imagine it to be like a scoop of ice cream falling out of a cone (Figure 2).
In majority cases, SCFE occurs without any underlying cause. However, in about 5% cases, an underlying hormonal problem may be identified. The common hormonal problems which can cause SCFE include hypothyroidism, renal osteodystrophy with secondary hyperparathyroidism and children with growth hormone deficiency on growth hormone therapy.
Severe Vitamin D deficiency is commonly noted in children with SCFE. Also, incidence of SCFE is higher in children with Down’s syndrome.
SCFE occurs in growing children during the adolescent years (11 to 13 years in girls and 12 to 15 years in boys). It affects boys more commonly than girls.
Children with SCFE are generally over-weight/ obese.
Children with SCFE usually present with hip, groin or knee pain of insidious onset. In the initial stages, the pain is mild and many times mistaken for knee rather than hip problem.
The child starts walking with feet turned excessively outwards rather than straight ahead (out-toeing gait).
Types of SCFE:
Stable SCFE: Many children with SCFE have some pain but are still able to walk, either independently of with the help of crutches. Such children are said to have a ‘stable slip’. Children with a stable slip will usually walk with a limp. The foot of the affected side will appear to be turned outwards more than the normal side.
Unstable SCFE: Some children with SCFE present acutely with very severe pain and inability to bear weight on affected limb. Such children are said to have an ‘unstable slip’. This is an emergency, and the child must be brought to the hospital as soon as possible.
SCFE is diagnosed on the basis of clinical examination and plain X-rays. Blood investigations are done to look for underlying hormonal problems. Advanced imaging like CT-scan or MRI may be performed in special situations.
Treatment for surgery is always operative. There is no role for non-operative treatment in the management of SCFE.
Surgery in SCFE are broadly of two types:
In-situ fixation: As the name suggests, in this surgery, no attempt is made to reduce the slip which has already occurred. This surgery is performed in milder slips, and the aim of the surgery is to stabilize the femur head and prevent it from slipping even further. This is done by placing one or two screws in the bone to hold the femur head in place.
Modified Dunn osteotomy: This surgery is performed in more severe slips in order to correct the slip and restore the femur head to its normal position. If this is not done, the head heals in an abnormal position and the child will go on to have limitation of movements at the hip and the early onset of arthritis of the hip joint. This surgery consists of opening the hip joint, restoring the femur head to its normal position and fixing it with screws. This is a much more major surgery as compared to fixing the head in situ, and has a longer recovery.
Treatment of Slipped Capital Femoral Epiphysis can have a excellent outcome, provided the diagnosis is made and surgery performed early. However serious complications can occur in a certain proportion of cases. Occurrence of these complications may necessitate additional surgical interventions. The complications that can occur include:
– Avascular necrosis (AVN): AVN is a complication which occurs due to obstruction of blood supply to the femoral head. It occurs with greater frequency in severe and unstable SCFE. Occurrence of AVN is usually apparent within one year after occurrence of SCFE. Treatment options for AVN are limited and most of these adolescents need Total Hip Replacement surgery in early adult life.
– Chondrolysis: Chondrolysis is a complication in which the cartilage covering of the femoral head gets eroded and hip joint space is decreased. It leads to progressive stiffness of the hip joint.
– Osteoarthritis: Osteoarthritis of the hip joint may occur at long term follow-up. It occurs due to impingement of residual deformity at site of SCFE against the margins of the acetabulum. If detected early, surgery to relieve impingement may be recommended. However, once osteoarthritis is established, total hip replacement surgery is needed.
SCFE in the other hip:
A child who has had SCFE on one side has a 1 in 4 chance of developing the same problem on the other side as well. For this reason, a child with SCFE in one hip is regularly followed-up at least till the end of growth to enable early detection of SCFE in the other hip. In some cases, prophylactic screw insertion in the other hip may be recommended.