Slipped Capital Femoral Epiphysis
Slipped capital femoral epiphysis (SCFE) describes a condition of the hip joint in which the top part of the femur (epiphysis) slips off the rest of the bone through the growth plate (physis – in red) (Figure 1).
Frontal (AP) View Side (Lateral) View
Figure 1
This slipping can only happen in children who are still growing but usually occurs near the end of growth as the child is entering puberty. Since girls often start puberty before boys, girls are usually younger (average 12 years old) when affected compared to boys (13.5 years old).
SCFE is the most common hip problem in adolescents but is not common with an incidence of 2-10 per 100,000. It is more common in boys than girls and tends to occur in heavy-set children.
Uncommonly, the slipping can happen very quickly (acute or unstable) leading to significant pain and an inability to walk. It is much more common for the slipping to occur slowly (stable or chronic) leading to a limp that may vary in severity over time. The limp is very characteristic with the affected foot turned out and the patient leaning over the affected side when weight is applied to that leg. About one third of the patients with a stable or chronic slip complain of knee pain instead of hip pain.
SCFE can cause significant problems for patients in a number of ways. The slipping through the growth plate can result in significant deformity of the hip leading to joint problems later in life. Even more serious, the slipping can be so significant that it can stretch and tear blood vessels that supply nutrition to the portion of the thigh bone that forms the hip joint. The disruption of the nutrition (avascular necrosis or AVN) can lead to significant deformity of the hip joint resulting in permanent stiffness and pain.
The goal of treatment of the hip with SCFE is to limit the amount of deformity caused by the slipping and do so in a manner that does not introduce any new problems. To do so, the problem must be recognized early before any significant slipping occurs. Surgical manipulation of slips can cause AVN so it is important to initiate treatment before significant deformity occurs. Thus, once the problem is recognized, measures to limit any further slipping should be instituted immediately.
There are a number of methods that have been utilized to stabilize the slipping but only one is in common practice today. One or two large screws are placed across the unstable growth plate in the operating room under general anesthesia. (Figure 2)
Frontal (AP) View
Figure 2
Modern equipment allows the surgeon to place the screws with a small incision that can be covered with a band aid. Most patients are able to leave the hospital the same day and will walk with crutches for four weeks. Once the physis has healed, the patient will be able to resume all activities including sports.
Since removal of the screw after the physis has stopped slipping can be associated with a number of complications, they are usually left in place throughout life. The screws are made of inert metals (titanium or stainless steel) and are almost completely encased in bone if properly placed. The patient should not be able to feel the screw nor should it impede any physical activity. If the patient continues to feel pain in the hip or thigh it is important to inform his / her physician immediately.
It is important for patients and their parents to realize that SCFE can occur in either hip. If a patient has a slip in one hip, there is approximately a 30% chance that the other hip will slip as well. Of these 30%, the “other hip slip” occurs at the same time as the initial slip half the time (synchronous slip) with other half usually within 18 months of the first slip (asynchronous slip) . Therefore, every patient diagnosed with a SCFE must have the other hip scrutinized not only at the time of diagnosis but with each subsequent follow-up visit as well. Patients and parents are instructed that if any symptoms of hip or knee pain, especially when associated with the characteristic limp, appear then the patient should stop walking on the bothersome leg and be seen immediately by an orthopaedic surgeon. The best treatment for SCFE is to stop the slip before there is deformation of the hip bone.
In summary, while SCFE is not common, it is the most common hip problem in adolescents. The problem usually occurs in children just as they are beginning puberty and is associated with obesity and male gender. Patient complaints include hip and / or knee pain and usually a characteristic limp or inability to bear weight. Treatment is aimed at preventing bone deformity by pinning the slip in place with a screw that is placed through a small incision in the operating room. It is important to scrutinize both hips as the problem can occur on either side in a synchronous or asynchronous fashion.