Conditions I treat......... Slipped Upper Femoral Epiphysis (SUFE)

No other pediatric orthopedic condition engenders the broad spectrum of mild to severe like SUFE.....

Pinning in situ for mild slips

In Slipped upper femoral epiphysis (SUFE), the femoral head (ball) has tipped off the neck through failure of the growth plate interface between the two. If the slip is mild (i.e. anatomy is not too distorted) further migration of the femoral head can be arrested by passing a screw across the growth plate. Often, the residual deformity is mild and with growth smoothes out through a process known as bone remodelling.

**Clinical Case:** X-ray of a 9 year boy with hip pain after physical education session but able to walk. The AP radiograph looks fairly innocuous but the frog lateral view revels a mild stable slip. The slip was fixed with a single screw inserted under x-ray guidance across the growth plate. At 1 year following surgery the step at the site of the slip has rounded off through remodelling.

Intracapsular osteotomy for acute deformity correction

When a severe slip occurs it may do so slowly (often over many weeks or months) or suddenly (usually after an accident). A sudden (acute) severe slip is a very bad prospect as there is a significant risk of the blood vessels to the femoral head being damaged causing progressive necrosis and collapse of the femoral head with early arthritis. In such instances, both the severe deformation of the anatomy and its unstable nature threatening the blood supply need to be addressed. This is usually done by surgery to open the hip, shorten the femoral neck to detension the neighbouring blood vessels and then place the femoral head back on. The femoral head is usually stabilised with two screws. Despite optimal treatment there is a significant risk of the blood supply to the femoral head being compromised and patients and their families need to be counselled appropriately.

**Clinical Case:** 13 year old boy presenting with severe slip that was unstable (patient unable to weightbear on affected leg). After a fortnight to allow the blood supply to the injured zone to settle, the patient underwent open reduction with shortening of the neck, reallignment of the femoral head and fixation with two screws (in unstable slips two screws are needed to prevent rotation about the axis of a single screw). At 1 year following surgery, the growth plate appears to have fused with no features of damage to the blood supply to the femoral head.

Pinning in situ for severe stable slips

Sometimes a slip takes place over a long time - almost in slow motion. As the femoral head slips off, adaptive changes in the bone smooth out and compensate for the deformity. Often these patients present with background pain for some time. Two issues arise - (1) whilst the growth plate is open, the femoral head can keep on slipping and (2) the more severe the magnitude of the ongoing slip, the greater the deformity in the femoral head. There are good studies to suggest that the distorted anatomy resulting from a severe stable slip will eventually lead to degenerative change in the joint and painful arthritis. Therefore even if the hip stops slipping, the deformity it has created can not be left untreated.

My favoured approach is to arrest the slip with a single screw. This stops the slip getting any worse and also helps ease the pain associated with the instability. The deformity in the femoral head can be addressed once growth is complete and the anatomy is static. Therefore these patients do need follow up to completion of growth when further surgery can be undertaken to correct the deformity.

**Clinical case:** 13 year old boy with bilateral chronic stable slips presenting with a few months of hip pain. These slips occur very slowly over weeks with the patient able to walk. The concern is that the hips can continue to slip with this instability causing pain. Stabilising the slips with screws offers pain relief and also stops the defomrity from getting worse. The x-ray following surgery shows that there is likely to be impingement (painful contact) between the prominent neck and the edge of the socket. Left untreated this will give rise to arthritis in adult life. My preference is to wait until the child has stopped growing at age 15-16 years and then correct the deformity through a femoral osteotomy away from the joint where there is less risk of avascular necrosis developing.

Deformity correction for severe stable slips

Often there are several deformities which need to be addressed in the chronic slip. There's usually a deformity in two planes (in actuality it's the same deformity but on an oblique plane.....) as well as an added rotational element. Left untreated severe stable slips do manifest arthritis in later life. My preference is to correct the deformities in the femoral bone away from the joint (and the crucial blood vessels supplying the femoral head). The femoral osteotomy enables angular correction in both planes as well as correcting the rotation.