These tests are indicated in the case of:
- Observed pelvic asymmetry and functional scoliosis and/or abnormal knee fold height upon inspection.
General Impression Of Leg Length
Procedure
- The patient lies on the examination table in supine position, with both hips and knees in 90° flexion.
- The examiner supports the lower legs and stands at the side/foot end of the examination table [Figures 44a, 44b].
Figure 44a
Figure 44b
- Note any difference in knee height (difference in length of upper legs).
- Ask the patient to lie in prone position, with both knees in 90° flexion.
- The examiner stands at the foot end or at the side of the examination table [Figure 45].
Figure 45
- Note any difference in the height of the soles of the feet (difference in lengths of lower legs).
Plank Test
- The patient stands up straight, with knees extended as far as possible and feet next to each other.
- Examiner stands behind the patient.
- One or more blocks of different thicknesses (0.5, 1.2 or 3 cm) are placed under the leg that is too short.
- Note whether the pelvis (iliac crests and posterior superior iliac spine) lies in a horizontal position (both knees extended).
- Assess by how many centimetres the heel needs to be elevated for a horizontal position of the pelvis to be achieved.
- Inspect and/or palpate the pelvis on both the ventral and dorsal sides (eyes level with pelvis).
- If after correction the height of the knee folds is the same, when this was not the case before, the difference in length lies in the lower leg.
- If the pelvic asymmetry persists, this may possibly be due to muscle contractures.
- Assess the effect on the spine (disappearance of the scoliosis).
- If the scoliosis persists, this is referred to as structural scoliosis.
- Correlate the findings with the position of the spine by having the patient sit on a stool with their back facing the examiner.
- In the case of functional scoliosis based on a difference in leg length, the curvature should disappear in the sitting position as the difference in leg length has no effect in this position.
- This method has an interobserver standard deviation of about 0.5 cm.
- The most reliable method remains radiographic measurement.
- Correction for a difference in leg length of between 1.5 and 4 cm can usually be adequately resolved using conservative measures (e.g. elevated shoes), with which the entire difference, as measured by the block test, is corrected for.
- Differences in leg length of < 1.5 cm are usually only corrected in the case of athletes.