248


PART IV THE LOWER EXTREMITY Clinical Connection 11.2


Hip abductor weakness can result in a gait pattern known as a Trendelenburg gait (or gluteus medius gait). A clinical sign of hip abductor weakness is when the pelvis on the non–weight-bearing side drops inferiorly during single leg stance. This inability to maintain a level pelvis during a single leg stance is referred to as a Trendelenburg sign. For example, a person with a positive Trendelen- burg sign who stands only on the right leg would be unable to hold the pelvis level. The left side of the pelvis drops because of weakness of the right hip abductors. Normally, the right hip abductors would work in a reversal of muscle action to pull the right iliac crest toward the right greater trochanter. If they are weak and unable to perform this action suffi ciently, the counterweight of the left leg will pull the left pelvis inferiorly.


A common compensation for this inferior pelvic tilt is to laterally bend the trunk to the side of muscle weakness. This lateral bend shifts the center of gravity and weight of the trunk and upper body back over the weight-bearing leg. This pelvic drop with compensatory lateral trunk bending is referred to as a Trendelenburg gait.


Clinical Connection 11.3


Piriformis syndrome is a neuromuscular disorder in which piriformis dysfunction compresses the sciatic nerve at its exit through the sciatic notch below the piriformis muscle. The compression can result from a shortening or spasm of the piriformis from direct trauma, spine or sacroiliac joint dysfunction, injury, or overuse. Symptoms associated with piriformis syndrome include pain, numbness, and tingling in the posterior hip region. Typically, the symptoms increase during sitting or squatting, but they can be exacerbated by walking and other activities. Medical treatment often includes nonsteroidal anti- infl ammatory drugs and muscle relaxants. Physical therapy interventions include ultrasound, soft tissue mobilization, piriformis stretching, thermal modal- ities, therapeutic exercise, and various treatments to the lumbar spine.


MEDIAL ROTATORS Gluteus maximus (cut) Gluteus medius (cut)


Gluteus minimus


Piriformis


Gemellus superior


Obturator externus


Gemellus inferior


Sacrotuberous ligament


Sacrospinous ligament


Sciatic nerve


Quadratus femoris


Figure 11.29 Hip lateral rotators. The gluteus maximus and gluteus medius are resected to reveal the deep rotators of the hip.


The medial rotators of the hip function as primary movers of the hip in other directions, but portions of their muscle bellies function as secondary hip medial rotators. These include the anterior fi bers of each of the following muscles: gluteus medius and gluteus minimus, tensor fasciae latae, adductor longus, adductor brevis, and pectineus. As the hip approaches 90° of fl exion, the orien- tation of these fi bers becomes more perpendicular to the vertical axis of the hip rotation. This change in alignment increases the ability of the muscles to generate a medial rotation torque. Some lateral rotator muscles switch their function from lateral rotators to medial rotators as the hip approaches 90° of fl exion. This change in orienta- tion explains why hip lateral rotators are lengthened and stretched at end ranges of hip medial rotation when the hip is extended but are stretched in lateral hip rotation when the hip is fl exed.


Both the lateral and the medial rotators have an important function when the leg is in contact with the ground. When standing on the right leg with the left leg unloaded, activating the right lateral rotators rotates the pelvis to the left in the horizontal plane (the left iliac crest rotates backward). This type of activity is seen during a cutting motion to the left while running. The person running plants the right foot and turns sharply to the left. During the gait cycle, the medial rotators play a role in rotating the pelvis on the side of the swing leg toward the weight-bearing stance leg. They medially rotate the pelvis in the horizontal plane over the fi xed femur of the stance leg. Figure 11.30 illustrates the left innominate bone rotating about the right hip as the left iliac crest moves forward.


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