Dunn describes six clinical presentations of slipped upper femoral epiphysis, each needing a different treatment. He details an open cervical osteotomy that shortens the neck to reposition the femoral head without stretching its blood supply. Outcomes are reported across 41 hips treated by closed pinning or open reduction.
The central lesson is vascular: in chronic slip the retinacular vessels on the posterior neck shorten to match the displaced head. Force the head back onto a full-length neck and you stretch those vessels into ischemia. This single fact explains why closed manipulation is reserved for the rare true-acute slip seen within hours.
Dunn's answer is to shorten the neck (the trapezoid osteotomy) or carefully advance the synovium, so the head can be replaced without tension. When you see acute-on-chronic slip with a posterior beak, do NOT crank on it. The physeal status is the other decision node: open physis permits cervical realignment, closed physis forbids it and pushes you toward trochanteric osteotomy.
This paper is a foundation for the modern Dunn and modified Dunn procedures, and its vessel-tension reasoning is why AVN remains the feared complication of aggressive reduction in SUFE.
Dunn describes six clinical presentations of slipped upper femoral epiphysis, each needing a different treatment. He details an open cervical osteotomy that shortens the neck to reposition the femoral head without stretching its blood supply. Outcomes are reported across 41 hips treated by closed pinning or open reduction.
The central lesson is vascular: in chronic slip the retinacular vessels on the posterior neck shorten to match the displaced head. Force the head back onto a full-length neck and you stretch those vessels into ischemia. This single fact explains why closed manipulation is reserved for the rare true-acute slip seen within hours.
Dunn's answer is to shorten the neck (the trapezoid osteotomy) or carefully advance the synovium, so the head can be replaced without tension. When you see acute-on-chronic slip with a posterior beak, do NOT crank on it. The physeal status is the other decision node: open physis permits cervical realignment, closed physis forbids it and pushes you toward trochanteric osteotomy.
This paper is a foundation for the modern Dunn and modified Dunn procedures, and its vessel-tension reasoning is why AVN remains the feared complication of aggressive reduction in SUFE.