Baker’s Cyst

 

A baker’s cyst is a benign swelling behind the knee. A baker’s cyst is also known as popliteal cyst which lies posterior to the medial femoral epicondyle. The cyst is connected to the knee joint through a valvular opening. Knee effusion from intra-articular pathology allows the fluid to go through the valve to the cyst in one direction. The cyst is located between the semi membranous and medial gastrocnemius muscles. 

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The patient usually has swelling behind the knee, with pain, fullness and tenderness. A baker’s cyst is easier to see with the knee fully extended. Diagnosis is confirmed by MRI that will show the associated intra-articular pathology. Ultrasound is helpful as well.  These tests are important especially if the cyst is found to be outside of its typical position.

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The two most common causes of baker’s cyst are knee arthritis and meniscal tear. Treatment of painful large cysts may include ice, compressions wrap, corticosteroid medication, strengthening exercises and aspiration of the cyst. Recurrence of baker’s cyst is common if the intra-articular pathology continues. The best treatment is arthroscopy and debridement of the intra-articular pathology.

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The cyst may burst causing calf pain and swelling. Rule out deep venous thrombosis or thrombophlebitis.

Popliteal cysts in children is a common soft tissue mass at the back of the knee. It occurs more in boys and it is asymptomatic. It is not a tumor. It is treated by observation, no surgery needed. It is not associated with a meniscal tear.

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Gait

Gait is the pattern of how a person walks. We will be discussing different gait abnormalities.

Antalgic gait

Antalgic gait is a painful gait. A patient with antalgic gait does not want to spend time on the one leg due to pain. A patient wants to get their weight off the affected extremity. When pain is increased by walking, it leads to an antalgic gait (Figure 1).

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An antalgic gait can be caused by multiple factors due to pain in any part of the lower extremity. It is usually caused from hip or knee pathology or from severe disc radiation symptoms (Figure 2).

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The pain can be helped by using a cane on the opposite side of the painful extremity.

Trendelenburg gait

Trendelenburg gait is an abnormal gait that is usually found in people with weak abductor muscle of the hip which is supplied by the superior gluteal nerve. The patient cannot abduct the affected hip due weakness of the abductor muscles on the affected side. If the patient has weakness on one side of the pelvis and when the patient stands on that side, the pelvis on the contralateral side will drop. This is called Trendelenburg sign. A positive Trendelenburg sign occurs when there is dysfunction of the abductor muscles and the body is unable to maintain the center of gravity on the side of the stance leg (Figures 3, 4). The patient will show an excessive lateral lean to keep the center of the gravity over the stance leg.

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Weakness can also occur in patients with L5 radiculopathy or avulsion of the abductor muscle tendon (Figure 5) which occurs with increasing frequency after hip replacement surgery.

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The superior gluteal nerve injury is a major factyor in this gait. With bilateral weakness of the abductor muscles, the patient will have dropping of the pelvis on both sides during walking which leads to a waddling motion. This gait is seen in patients with myopathies.

Slap gait

Slap gait occurs due to weakness of the foot and ankle dorsiflexors which allows the foot slap down on the floor with each step. Slap gait is a heel gait abnormality that can be diagnosed by hearing the patient walk with a normal walking gait, the heel strikes the ground first followed by controlled relaxation of the foot and ankle dorsiflexors in order to allow the forefoot to come in contact with the ground

Steppage gait

Foot drop gait or steppage gait is due to total paralysis of the ankle and foot dorsiflexors (Figure 6). it is sometimes called neuropathic gait. A common symptom of foot drop is a high steppage gait that is often characterized by raising the thigh up in an exaggerated fashion while walking. The patient must externally rotate the leg or flex the hip or knee to raise the foot high enough to avoid dragging the toes along the ground. If the patient has foot drop then they have to have a high steppage gait or else they will trip on the foot and fall forward.

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Conditions causing foot drop include L4-L5 disc herniation, a herniated disc compressing the L5 nerve root may cause foot drop, lumbosacral plexus injury due to pelvic fracture (Figure 7), hip dislocation leading to injury of the common peroneal nerve (Figure 8) and injury to the knee as knee dislocation (Figure 9).

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Wide based gait

A wide based gait occurs due to myelopathy and neurological disorders. This gait disturbance is described as clumsy, staggering movements. It can be associated with cervical or thoracic spine pathology. Patient example of myelopathy with significant cervical spine disc compression of the spinal cord can be seen in Figure 10.

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Patient will have a slow, wide, broad based ataxic gait. The patient will have a wide stance as they try to maintain balance. There will be unsteadiness of the trunk with excessive shift in the center of the gravity.

Gluteus maximus gait

When the gluteus maximus muscle (Figure 11) is week, the trunk lurches backwards (extension of the trunk). It occurs at heel strike on the weakened side to interrupt the forward motion of the trunk. This compensates for weakness of hip extension. The function of the gluteus maximus muscle is external rotation and extension of the hip joint.

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