REIDER PART 212

172_Chaptkr 5_Pelvis, Hip, and Thigh

Figurę 5-12. Measuring a functional leg length discrepancy.

Figurę 5-13. Visual method for assessing leg length discrepancy. A, Technique. B and C, Close-up, comparing medial malleoli (arrows in C).

table, and the examiner stands at the foot of the exami-nation table. The examiner aligns the patient as straight as possible and, grasping the patienfs feet, shifts the lower extremities until a linę drawn straight between them also passes straight down the center of the patients body (Fig. 5-13A). The examiner then compares the position of the two medial malleoli (Fig. 5-13B and C). If one is proxi-mal or distal to the other, a leg length discrepancy exists. The difference in the position of the two malleoli is the magnitude of the leg length discrepancy.

Abduction Contracture. Figures 5-14A through 5-15B illustrate how an abduction or adduction contracture of the hip can produce a functional limb length discrepancy. In Figurę 5-14A, the model is simulating an abduction contracture of the hip, a condition in which tightness of the hip abductor muscles prevents the patient s hip from being adducted to the neutral (0°) position. In order to align the involved limb perpendicular to the floor, the patient has to drop the pelvis on the involved side. This causes the involved limb to be functionally long. Placing a lift on the uninvolved side compensates for the patient’s functional lengthening of the involved side, although the pelvis is obliąue (Fig. 5-15B). In the absence of a lift, patients may also shorten the involved limb by flexing the ipsilateral knee.

Adduction Contracture. In Figurę 5-15A, the model is simulating an adduction contracture of the left hip. In this case, contracture of the adductor muscles prevents the involved hip from being abducted to at least a neutral position. In this case, the lower extremities may be brought into proper alignment by placing a lift on the involvcd side (see Fig. 5-15B). Again, this compensates for the contracture although it causes an obliąue pelvis. In the absence of a lift, the patient may intuitively compensate for the functional leg length discrepancy by flexing the contralateral knee or walking on the toes of the short limb.

Femoral Versus Tibial Discrepancy. If a true leg length discrepancy is present, further examination may deter-mine whether the discrepancy is in the femur or the tibia. To detect a femoral length discrepancy, the patient lies supine on the examination table with the hips and the knees flexed to 90°. If one femur is longer than the other, the patienTs knees rest at different heights from the examination table (Fig. 5-16). To detect a tibial length discrepancy, the patient is positioned prone with the knees again flexed to 90°. If the tibias differ in length, the

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