This 1976 paper by Tönnis establishes statistically derived normal values for hip radiographic measurements in children and adults. It analyzes 2,294 acetabular angles in children and 817 hip joints in adults to define quantitative thresholds separating normal hips from dysplastic ones. It also introduces the Hip Value — a composite score combining the ACM angle, CE angle, and MZ decentralization distance.
When you measure a child's acetabular index, Table 2 is the reference that tells you whether that number is reassuring, borderline, or pathological — stratified by the child's exact age, sex, and side.
For borderline cases (between s and 2s), this paper provides the outcome data: nearly 1 in 5 will progress to definite dysplasia. That is the evidence base for including borderline infants in splinting protocols rather than watching.
For adults presenting with hip pain and radiographic dysplasia, the Hip Value composite score integrates acetabular depth (ACM angle), coverage (CE angle), and subluxation distance (MZ) into a single number that classifies severity. A Hip Value of 16-21 signals mild deformity; ≥22 signals severe deformity warranting more aggressive management.
The Tönnis coxarthrosis grading system introduced in this paper (Grades 1-3) became the standard radiographic staging tool used in hip preservation reporting worldwide. You will see it cited in every periacetabular osteotomy and hip arthroscopy outcomes paper.
This 1976 paper by Tönnis establishes statistically derived normal values for hip radiographic measurements in children and adults. It analyzes 2,294 acetabular angles in children and 817 hip joints in adults to define quantitative thresholds separating normal hips from dysplastic ones. It also introduces the Hip Value — a composite score combining the ACM angle, CE angle, and MZ decentralization distance.
When you measure a child's acetabular index, Table 2 is the reference that tells you whether that number is reassuring, borderline, or pathological — stratified by the child's exact age, sex, and side.
For borderline cases (between s and 2s), this paper provides the outcome data: nearly 1 in 5 will progress to definite dysplasia. That is the evidence base for including borderline infants in splinting protocols rather than watching.
For adults presenting with hip pain and radiographic dysplasia, the Hip Value composite score integrates acetabular depth (ACM angle), coverage (CE angle), and subluxation distance (MZ) into a single number that classifies severity. A Hip Value of 16-21 signals mild deformity; ≥22 signals severe deformity warranting more aggressive management.
The Tönnis coxarthrosis grading system introduced in this paper (Grades 1-3) became the standard radiographic staging tool used in hip preservation reporting worldwide. You will see it cited in every periacetabular osteotomy and hip arthroscopy outcomes paper.