Leg Length measurement tests assesses actual and functional leg length differences.
Measurement of an actual difference in leg length is performed with the patient standing by placing shims of varying thickness (0.5, 1, 2 cm ) underneath the shorter leg until the pelvic obliquity is fully compensated.
Compensation of the pelvic obliquity is usually readily apparent, especially when the patient bends forward from a standing position.
With the pelvis horizontal, the leg length difference corresponds to the total height of the shims placed beneath the foot. Evaluating leg length difference by palpating the iliac crests from behind the patient is often imprecise. Often the iliac wings (iliac crests) will not be at the same level although radiographic findings confirm identical leg length and a normal vertical spine. Asymmetric iliac wings are frequently encountered in conditions such as hip dysplasia. The iliac wing on the dysplastic side is usually smaller. Often only a pelvic radiograph obtained with the patient standing and showing the sacrum and lower lumbar spine will allow one to draw reliable conclusions about the type and severity of the leg length difference.
Where placement of shims cannot compensate the pelvic obliquity, the patient has a fixed deformity of one or more joints or a fixed scoliosis leading to a functional leg length difference. This functional difference occurs as a result of a flexion or adduction contracture in the hip. The pelvis dips toward the normal side; the normal leg appears lengthened and the affected leg shortened.
An abduction contracture in the hip causes a functional leg length difference. The pelvis dips toward the affected side; the normal leg appears shortened and the affected leg lengthened. An actual leg length difference is best evaluated and measured with the patient standing, a functional difference with the patient supine.
One can also use direct leg length measurement to determine leg length difference by using a tape measure to measure the distance between the anterior superior iliac spine and the medial malleolus.
Galeazzi Test or Allis Test assesses leg length difference.
The patient is supine with the knees flexed 90° and the soles of the feet at on the examining table. The examiner assesses the position of both knees from the end of the table and from the side.
Normally both knees are at the same level. Where one knee is higher than the other, either the tibia of that side is longer or the contralateral tibia is shorter. Where one knee projects farther forward than the other, either that femur is longer or the contralateral femur is shorter.
The test for assessment of femur length is indicated as an additional test for evaluating hip dislocation. However, in such a case there is only an apparent difference in length; the femurs are the same length but one thigh appears shorter due to the hip dislocation.
Note that the Galeazzi test will yield a false-negative result in cases of bilateral hip dislocation.
Chiropractors assess leg length with the patient prone. The comparative lengths of the legs are compared by observing the heels or the medial malleoli. If a discrepancy is noted, the knees are flexed to 90 degrees while maintaining neutral hip rotation, and the landmarks are reassessed to screen for a shortened tibia.
The patient is then positioned supine, and the leg lengths are reassessed using the same landmarks. Finally, the leg lengths are assessed using the long sit test.
Functional leg length inequality that is secondary to SI subluxation or dysfunction may reverse from the supine to sitting position, whereas anatomic leg length inequality or functional inequality secondary to dysfunction at other sites likely will not.
The patient stands with the feet shoulder-width apart. The clinician palpates the iliac crests, the ASISs, and the PSISs and compares the relative heights for asymmetry.
The patient is then positioned with the subtalar joints in neutral, the toes pointing forward, and the knees fully extended. The same landmarks are reassessed. If the second position corrects any asymmetry found in the first position, the test is positive for a functional leg length discrepancy and indicates that the leg is structurally normal but has abnormal joint mechanics.