Salter and Thompson studied serial radiographs of 1,057 children (1,264 hips) with Legg-Calvé-Perthes disease across four institutions. The central question: can the early subchondral crescentic fracture predict eventual femoral head involvement — before months of resorption make the answer obvious? This paper proposes the Salter-Thompson two-group classification based on that answer.
Before this paper, the Catterall classification could only be assigned after the resorptive phase was complete — often months after diagnosis. Leaving surgeons unable to stratify prognosis or commit to containment treatment at first presentation.
This paper changes that. When a child presents with a limp and hip pain, obtain AP and frog-lateral radiographs immediately. If you can see the subchondral crescentic fracture, its extent tells you exactly how much of the femoral head will ultimately be involved. No waiting required.
If the fracture extends less than halfway across the head (Group A, intact lateral margin), the child will almost certainly do well regardless of treatment. If it crosses the halfway point (Group B, absent lateral margin), you are looking at a 40-60% chance of a poor result without containment. And containment meaningfully improves that number.
The window is short. In children under age 4, the fracture disappears in as little as 3 months on average. Get the radiograph within 4 months of symptom onset, or you lose the one early prognostic sign that lets you act before the damage is done.
Salter and Thompson studied serial radiographs of 1,057 children (1,264 hips) with Legg-Calvé-Perthes disease across four institutions. The central question: can the early subchondral crescentic fracture predict eventual femoral head involvement — before months of resorption make the answer obvious? This paper proposes the Salter-Thompson two-group classification based on that answer.
Before this paper, the Catterall classification could only be assigned after the resorptive phase was complete — often months after diagnosis. Leaving surgeons unable to stratify prognosis or commit to containment treatment at first presentation.
This paper changes that. When a child presents with a limp and hip pain, obtain AP and frog-lateral radiographs immediately. If you can see the subchondral crescentic fracture, its extent tells you exactly how much of the femoral head will ultimately be involved. No waiting required.
If the fracture extends less than halfway across the head (Group A, intact lateral margin), the child will almost certainly do well regardless of treatment. If it crosses the halfway point (Group B, absent lateral margin), you are looking at a 40-60% chance of a poor result without containment. And containment meaningfully improves that number.
The window is short. In children under age 4, the fracture disappears in as little as 3 months on average. Get the radiograph within 4 months of symptom onset, or you lose the one early prognostic sign that lets you act before the damage is done.