In patients with a positive Trendelenburg’s sign, gait also is abnormal. Typically during the stance phase of the affected limb, the weakened abductor muscles allow the pelvis to tilt inferiorly over the swing limb. The patient compensates for the pelvic drop by lurching the trunk to the affected side to maintain the level of the pelvis throughout the gait cycle.
In the clinic
From time to time it is necessary to administer drugs intramuscularly, that is, by direct injection into muscles. This procedure must be carried out without injuring neurovascular structures. A typical site for an intramuscular injection is the gluteal region. The sciatic nerve passes through this region and needs to be avoided. The safest place to inject is the upper outer quadrant of either gluteal region.
The gluteal region can be divided into quadrants by two imaginary lines positioned using palpable bony landmarks (Fig. 6.49). One line descends vertically from the highest point of the iliac crest. Another line is horizontal and passes through the first line midway between the highest point of the iliac crest and the horizontal plane through the ischial tuberosity.
It is important to remember that the gluteal region extends as far forward as the anterior superior iliac spine. The sciatic nerve curves through the upper lateral corner of the lower medial quadrant and descends along the medial margin of the lower lateral quadrant.
Occasionally, the sciatic nerve bifurcates into its tibial and common fibular branches in the pelvis, in which case the common fibular nerve passes into the gluteal region through, or even above, the piriformis muscle.
The superior gluteal nerve and vessels normally enter the gluteal region above the piriformis and pass superiorly and forward.
The anterior corner of the upper lateral quadrant is normally used for injections to avoid injuring any part of the sciatic nerve or other nerves and vessels in the gluteal region. A needle placed in this region enters the gluteus medius anterosuperior to the margin of the gluteus maximus.
In the clinic
Compartment syndrome occurs when there is swelling within a fascial enclosed muscle compartment in the limbs. Typical causes include limb trauma, intracompartment hemorrhage, and limb compression. As pressure within the compartment elevates, capillary blood flow and tissue perfusion is compromised, which can ultimately lead to neuromuscular damage if not treated.
In the clinic
Muscle injuries to the lower limb
Muscle injuries may occur as a result of direct trauma or as part of an overuse syndrome.
Muscle injuries may occur as a minor muscle tear, which may be demonstrated as a focal area of fluid within the muscle. With increasingly severe injuries, more muscle fibers are torn and this may eventually result in a complete muscle tear. The usual muscles in the thigh that tear are the hamstring muscles. Tears in the muscles below the knee typically occur within the soleus muscle, though other muscles may be affected.
Injury to the hamstring muscles is a common source of pain in athletes, particularly in those competing in sports requiring a high degree of power and speed (such as sprinting, track and field, football) where the hamstring muscles are very susceptible to injury from excessive stretching.
The injury can range from a mild muscle strain to a complete tear of a muscle or a tendon. It usually occurs during sudden accelerations and decelerations or rapid change in direction. In adults, the most commonly injured is the muscle-tendon junction, which is a wide transition zone between the muscle and the tendon. An avulsion of the ischial tuberosity with proximal hamstring origin attachment is common in the adolescent population, particularly during sudden hip flexion because the ischial apophysis is the weakest element of the proximal hamstring unit in this age group (Fig. 6.64). Both ultrasound and MRI can be used to assess the hamstring injury with the MRI providing not only the information about the extent of the injury but also give some indication about the prognosis (future risk of re-tear, loss of function, etc).
In the clinic