Slipped capital femoral epiphysis is a condition in which the epiphysis on the femoral head is displaced posteriorly with respect to the femoral neck, altering the mechanics and articular structure of the joint and eventually causing inability to put any weight on the affected hip without pain.
There are various modes of treatment, designed to arrest slippage of the displaced epiphysis. Early diagnosis and treatment is essential to provide stability to the hip and avoid long-term complications such as osteoarthritis. The outcome deteriorates with the severity of the slip. This is because worsening of the slippage causes femoroacetabular impingement (FAI) which causes further damage to the labral cartilage at the acetabular rim. This alteration in bone morphology and damage to cartilage is responsible for the development of osteoarthritis over the long term.
The first step after the diagnosis of SCFE is made is preventing any loadbearing on the affected joint. The decision on which treatment to adopt will depend on:
The surgery is usually planned and carried out on a semi-urgent basis, within 24-48 hours, to prevent further joint damage.
In situ pinning has largely replaced open bone-peg epiphysiodesis with or without corrective femoral osteotomy. This older technique popular in the 1950s and 1960s had the advantage of closing the physis quickly and thus preventing any further displacement of the slipped epiphysis. It also avoided having to use screws and pins near the joint, as well as obviating screw removal. It fell out of favor largely due to the risk of recurrent slippage. In addition to the failure to arrest epiphyseal slippage, there was a higher rate of complications when bone-peg epiphysiodesis was utilized.
The most widely used procedure to correct stable slips of mild to moderate severity is now the single in situ fixation with a center-to-center screw, which passes across the growth plate to fix the femoral capital epiphysis . It has several advantages:
It is still undecided whether the use of a single or double screw is better suited to produce stability. While two screws make it more biomechanically strong, a single screw causes less damage to the articular surface and growth plate and reduced risk of avascular necrosis.
Osteonecrosis is a serious complication associated with closed reduction of the displaced capital epiphysis.
Open reduction with internal fixation uses a femoral osteotomy to reduce the deformity in the treatment of severe and chronic slips which limit function or are very painful. It is performed after the end of the growing period. Its use has become more popular in moderate slips, as well, to reduce the risk of hip impingement due to abnormal bone shape and cartilage damage. In the modified Dunn’s technique, a safe surgical hip dislocation is performed and a retinacular flap is created to protect the vascular supply to the femoral neck, and thus prevent avascular necrosis. The hip is corrected by putting it into flexion and valgus position, and derotating it.
While this procedure is thought to reduce the rate of avascular necrosis in unstable SCFE, it is not a routine procedure and its efficacy is yet to be unequivocally established. Some studies have concluded that there is no significant difference in outcome between in situ pinning and femoral osteotomy.
Others show that the rate of osteoarthritis is higher after osteotomy, about 65% after 28 years of follow up. Another study on moderate to severe slips treated with realignment found that almost 60% of patients eventually required some type of hip fusion or replacement, or suffered severe osteoarthritis.
Prophylactic pinning of the opposite hip has been practiced widely because of the high rate of bilateral SCFE with the second hip becoming symptomatic within 18 months of the first.
Surgery is usually coupled with physical therapy to build up hip and leg muscle strength to further support and correct hip joint action. Follow up for about 24 months is essential. Any underlying or coexisting medical conditions are also treated at this time.
A proper mode of treatment following early detection is associated with the lowest chance of limb shortening, osteoarthritis and limited hip movement.