1. Eighty-five per cent. of the seventy-five patients with coxa plana were males.

2. Bilateral coxa plana is not infrequent and should always be looked for. The condition may not occur in the two hips at the same time or in like degree.

3. Stature, obesity, and endocrine imbalances appear to be unimportant in influencing the incidence of the condition.

4. Trauma appears to be of importance only incidentally in increasing the symptoms and the activity of the process.

5. No definite epidemic or seasonal relationships are found.

6. The onset of symptoms and of roentgenographic changes usually occurs between the ages of three and ten years.

7. The pathological features are acute inflammation of the soft tissues about the neck, and their subsequent sclerosis, thickening, and avascularity.

8. Sclerotic changes about the neck are accompanied by a vascular disturbance in the femoral head, resulting in the bony changes characteristic of coxa plana.

9. There are three stages,—active, reparative, and residual.

10. Definite symptoms, physical signs, and roentgenographic evidence of the disease are always present in the active stage. Early diagnosis is essential for the best results in treatment.

11. Final impairment of function is not proportional to deformity of the head.

12. Adequate rest for the hip is the most important factor in obtaining a good result.

13. In our cases in the active stage, drilling of the femoral head for revascularization has halted the advance of the process and has resulted in earlier and more complete repair.

14. In the reparative stage, when activity has completely subsided, no treatment is usually indicated. In the residual stage, subtrochanteric osteotomy, or arthroplasty, may be desirable in selected cases.

15. Degenerative arthritis is a sequela in some cases.