Heyman and Herndon (1950) describe the Comprehensive Quotient, a standardized radiographic grading system for Legg-Perthes disease. It averages four component ratios — epiphyseal, head-neck, acetabular, and acetabulum-head — each compared to the contralateral normal hip. The paper asks whether one objective number can replace subjective normal/good/fair/poor grading.
When you grade a Legg-Perthes outcome, looking only at epiphyseal shape is not enough. A flat epiphysis scores poorly on the epiphyseal quotient, but if the neck, acetabulum, and head coverage are well-preserved, the hip as a whole may be several grades better than that single number implies.
This paper is why we evaluate the whole joint — epiphysis, neck morphology, acetabular depth, and head coverage. Rather than any one dimension alone. In practice: when reporting Legg-Perthes radiographic outcomes, measure all four components and report the average. A comprehensive quotient above 90% is a normal result; below 60% is a bad result that should prompt concern about long-term function.
This work laid the conceptual foundation for later, more widely adopted outcome systems in Legg-Perthes disease (Stulberg classification), all of which similarly evaluate the femoral head, neck, and acetabulum together rather than in isolation.
Heyman and Herndon (1950) describe the Comprehensive Quotient, a standardized radiographic grading system for Legg-Perthes disease. It averages four component ratios — epiphyseal, head-neck, acetabular, and acetabulum-head — each compared to the contralateral normal hip. The paper asks whether one objective number can replace subjective normal/good/fair/poor grading.
When you grade a Legg-Perthes outcome, looking only at epiphyseal shape is not enough. A flat epiphysis scores poorly on the epiphyseal quotient, but if the neck, acetabulum, and head coverage are well-preserved, the hip as a whole may be several grades better than that single number implies.
This paper is why we evaluate the whole joint — epiphysis, neck morphology, acetabular depth, and head coverage. Rather than any one dimension alone. In practice: when reporting Legg-Perthes radiographic outcomes, measure all four components and report the average. A comprehensive quotient above 90% is a normal result; below 60% is a bad result that should prompt concern about long-term function.
This work laid the conceptual foundation for later, more widely adopted outcome systems in Legg-Perthes disease (Stulberg classification), all of which similarly evaluate the femoral head, neck, and acetabulum together rather than in isolation.