Lines and Angles in Orthopedics

Table of Contents

Slipped Capital Femoral Epiphysis (SCFE)

Southwick angle and Klein's line SCFE
Above: Southwick’s angle
Below: Klein’s line

Southwick’s angle: Epiphyseal-shaft angle on lateral radiograph

  • <30 degrees: mild
  • 30-60 degrees: moderate
  • >60 degrees: severe

Klein’s line: Line drawn along superior border of femoral neck (AP x-ray)

  • In SCFE: will intersect less of the femoral head or not at all

Developmental Dysplasia of Hip (DDH)

hilgenreiner perkin shenton wiberg acetabular index

Hilgenreiner’s line: Horizontal line through triradiate cartilage of acetabulum – femoral head ossification must be below this line

Perkin’s line: Vertical line (perpendicular to Hilgenreiner’s line) from the lateral margin of ossified acetabular roof – femoral head ossification must be medial to this line

Shenton’s line: Smooth curved line connecting medial border of femoral metaphysis with superior border of obturator foramen – arc line should be continuous

Acetabular index: Angle that acetabular line (drawn from acetabular surface) makes with Hilgenreiner’s line – should be <25 degrees in >6 months old

Center edge angle of Wiberg: Angle between vertical line from center of femoral head to and line between edge of acetabulum to center of femoral head – <20 degrees is considered abnormal (reliable only in >5 year old)

1. Femoral head is above Hilgenreiner’s line and lateral to Perkin’s line
2. Shenton’s line is broken
3. Acetabular index increased
4. Center edge angle of Wiberg decreased

Coxa Vara

Hilgenreiner-epiphyseal angel: Angle between Hilgenreiner’s line and a line drawn parallel to capital femoral epiphysis (Increased in Coxa Vara)

Neck-shaft angle: Normal is 127 degrees (<120 degrees is Coxa Vara)

Congenital Talipes Equinovarus (CTEV)

Kite’s angle (AP Talo-calcaneal angle): Angle between lines drawn down the axis of Talus and Calcaenus

  • Normal: 20-40 degrees
  • CTEV: <20 degrees

Talus-first metatarsal angle: Normal is 0-20 degrees (Negative in CTEV)

Calcaneal fracture

Bohler’s angle: Angle between line drawn from the highest point of anterior process of calcaneus to the highest point of posterior facet AND a line drawn tangentially from posterior facet highest point to tuberosity superior edge (normal is 20-40 degrees)

  • Decreased in calcaneal fracture

Gissane’s angle: Angle formed by the downward and upward slopes of the calcaneal superior surface (normal is 120-145 degrees)

  • Increased in calcaneal fracture

Ward’s Neutral triangle: The vast majority of calcaneus fracture lines propagate through a hypodense region of bone called Ward’s neutral triangle.

Supracondylar fracture of humerus

Bauman’s angle (Humero-capitellar angle): Angle between line parallel to longitudinal axis of humerus and line along lateral epiphysis (Normal 70-75 degrees; best to compare with contralateral side)

Anterior humeral line: Line drawn along anterior surface of humerus cortex must pass through the middle third of capitellum


Cobb’s angle: A scoliosis is defined as a lateral spinal curvature with a Cobb angle of 10° or more

Other angles, lines and indices

Singh’s index: Grading of osteoporosis by quantifying trabeculae in neck of femur

Ward’s triangle: Femoral neck

Babcock’s triangle: Femoral neck

Fairbank’s triangle: Congenital coxa vara, Perthes disease, Nonunion neck of femur

Pauwel’s angle: Neck of femur fracture

Meary’s angle and calcaneal pitch: Pes planus and cavus

Distal radial indices: Radial length, volar tilt, ulnar variance

Gilula lines: Congruent arcs in normal wrist X-rays

Matta’s roof arc angle: Acetabular fractures

Alpha angle: Femoro-acetabular impingement

Metaphyseal-Diaphyseal angle of Drennan: Blount’s disease

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