Scissor gait is a walking abnormality characterized by the legs crossing or overlapping in a scissor-like motion during movement. This distinctive pattern is a form of spastic gait, resulting from increased muscle tone, or hypertonia, primarily in the lower limbs. This involuntary stiffness makes it difficult to move the legs freely, leading to the abnormal stepping pattern. The gait is almost always a symptom of an underlying neurological disorder affecting the central nervous system.
Visual Description of Scissor Gait
The most defining visual characteristic of the scissor gait is the inward movement of the legs, causing the knees and thighs to scrape or cross with each step, much like the blades of a pair of scissors. This movement results from extreme adduction, where the strong adductor muscles of the inner thigh remain tightly contracted. The legs, hips, and pelvis often remain partially flexed, creating a stiff, crouched appearance.
Walking becomes a slow and effortful process because the person must use extra energy to overcome the constant inward pull of the spastic muscles. Due to the stiffness and internal rotation at the hip, the base of support becomes narrow, and the feet may even cross the midline of the body, increasing the risk of tripping and falling. Individuals with this gait often exhibit plantar flexion of the ankle, forcing them to walk on their toes or the balls of their feet.
Primary Underlying Causes
The root cause of scissor gait is hypertonia, an abnormally high muscle tone, which stems from damage to the central nervous system (CNS). This damage typically affects the upper motor neurons, leading to a loss of inhibitory control over muscle contraction. The resulting over-excitability causes persistent, involuntary tightening, or spasticity, most noticeably in the hip adductors and hamstrings.
The most frequent cause of scissor gait, especially in children, is Cerebral Palsy (CP), specifically spastic diplegia. Spastic diplegia is a form of CP where the motor impairments predominantly affect the legs. The brain injury that causes CP disrupts the pathways necessary for muscle control and coordination, resulting in the characteristic spasticity and gait abnormality.
Other neurological conditions that cause upper motor neuron lesions can also lead to a scissor gait. These conditions include Multiple Sclerosis, injuries to the spinal cord (such as trauma or tumors), stroke, or traumatic brain injury. All these conditions can result in the neural damage necessary to cause spasticity and this particular walking pattern.
Management and Treatment Approaches
Management for scissor gait focuses on reducing spasticity and improving walking mechanics to enhance mobility. Treatment is often multi-faceted, combining physical interventions, medication, and, in some cases, surgical procedures. Early intervention is beneficial for improving functional outcomes and maximizing long-term independence.
Physical therapy is a cornerstone of non-surgical treatment, utilizing stretching to increase flexibility and exercises to strengthen opposing muscle groups. Gait training is important, as individuals need to learn new, more efficient motor habits even after spasticity is reduced. Orthotic devices, such as braces or splints, can also be used to support proper leg alignment, counteract the inward pulling of tight muscles, and prevent the legs from crossing.
Medications are primarily used to manage the underlying spasticity. Oral muscle relaxants, such as baclofen, can help decrease generalized muscle hyperactivity, though they may have side effects like drowsiness or weakness. For localized reduction of spasticity, Botulinum Toxin (Botox) injections can be administered directly into the tight muscles, temporarily blocking the nerve signals that cause contraction, with effects typically lasting three to six months.
When conservative treatments are insufficient, surgical options may be considered to correct muscle tightness or nerve input. Adductor lengthening surgery involves surgically lengthening the inner thigh muscles to reduce their pull and allow the legs to separate. A neurosurgical procedure called Selective Dorsal Rhizotomy (SDR) involves selectively cutting the overactive nerve fibers in the spinal cord that are responsible for the spasticity.