blood supply. Diagnosis The diagnosis is a combination of clinical suspicion plus radiological investigation. Children with a SCFE experience a decrease in their range of motion, and are often unable to complete hip flexion or fully rotate the hip inward. 20–50% of SCFE are missed or misdiagnosed on their first presentation to a medical facility. SCFEs may be initially overlooked, because the first symptom is knee pain, referred from the hip. The knee is investigated and found to be normal. The diagnosis requires x-rays of the pelvis, with anteriorposterior (AP) and frog-leg lateral views. The appearance of the head of the femur in relation to the shaft likens that of a "melting ice cream cone", visible with Klein's line. The severity of the disease can be measured using the Southwick angle. Classification Atypical/Typical Loder classification Stable Unstable, practically defined as when the patient is unable to ambulate even with crutches Temporal Acute Chronic Acute-on-chronic Radiological Grade I = 0–33% slippage Grade II = 34–50% slippage Grade III = >50% slippage Treatment The disease can be treated with external in-situ pinning or open reduction and pinning. Consultation with an orthopaedic surgeon is necessary to repair this problem. Pinning the unaffected side prophylactically is not recommended for most patients, but may be appropriate if a second SCFE is very likely. Once SCFE is suspected, the patient should be non-weight bearing and remain on strict bed rest. In severe cases, after enough rest the patient may require physical therapy to regain strength and movement back to the leg. A SCFE is an orthopaedic emergency, as further slippage may result in occlusion of the blood supply and avascular necrosis (risk of 25 percent). Almost all cases require surgery, which usually involves the placement of one or two pins into the femoral head to prevent further slippage. The recommended screw placement is in the center of the epiphysis and perpendicular to the physis. Chances of a slippage occurring in the other hip are 20 percent within 18 months of diagnosis of the first slippage and consequently the opposite unaffected femur may also require pinning. The risk of reducing this fracture includes the disruption of the blood supply to the bone. It has been shown in the past that attempts to correct the slippage by moving the head back into its correct position can cause the bone to die. Therefore the head of the femur is