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Which phase of gait is affected most in a patient with quadriceps atrophy?
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Quadriceps weakness is most likely to affect the stance phase of the gait cycle, making midstance the correct answer.
During the normal stance phase of gait, the quadriceps contracts to prevent buckling of the knee. In a patient with quadriceps atrophy, the patient leans forward at the hip causing the center of gravity to fall anterior to the knee. This causes the knee to go into hyperextension. In contrast, weakness of the hamstrings or the hip flexors are most likely to affect the swing phase of gait by limiting limb advancement.
Lim et al. discuss the evaluation of the elderly patient with an abnormal gait. They urge the clinician to identify and treat the cause of the gait disturbance, if possible. Common treatable neurologic causes include normal pressure hydrocephalus, vitamin B12 deficiency, Parkinson's, alcoholism, and medication toxicity. Common treatable musculoskeletal causes include cervical myelopathy, spinal stenosis, and contractures.
Video V shows how gait is affected when there is a quadriceps deficiency.
Answers 1, 2, 3, 5: The quadriceps is largely silent during the swing phase of gait.
Lim MR, Huang RC, Wu A, Girardi FP, Cammisa FP Jr.
J Am Acad Orthop Surg. 2007 Feb;15(2):107-17. PMID: 17277257 (Link to Abstract)
Lim, JAAOS 2007
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Which of the following descriptions of muscle activity during normal gait is correct?
Gastrocnemius-soleus contracts eccentrically during heel strike
Gastrocnemius-soleus contracts concentrically during heel strike
Gastrocnemius-soleus contracts concentrically during swing phase
Tibialis anterior contracts concentrically during toe-off
Tibialis anterior contracts eccentrically at heel strike
One stride (heel strike to heel strike of one leg) of normal gait has been divided into the stance (62%) and swing (38%) phases. The stance phase is further divided into heel strike, foot flat, and toe off. Proper gait requires coordinated contraction of the leg muscles.
The tibialis anterior (TA) muscle fires eccentrically at heel strike to lower the foot to the ground, while the gasto-soleus (GS) complex is dormant. The TA then relaxes, while the GS eccentrically contracts as the body’s weight is transferred forward over the foot during foot-flat. As the foot propels the body forward during toe-off, the GS contracts concentrically, while the TA remains dormant. As swing commences, the TA then fires concentrically producing dorsiflexion to clear the foot over the ground while the GS relaxes. Certain conditions like cerebral palsy result in improper firing of the muscles during the gait cycle, resulting in altered gait mechanics.
Illustration A demonstrates the phases of the gait cycle.
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The primary antagonist of the anterior tibial tendon is innervated by which of the following nerves?
Superficial peroneal nerve
Deep peroneal nerve
Posterior tibial nerve
The primary antagonist of the anterior tibial tendon is the peroneus longus, which is innervated by the superficial peroneal nerve.
The peroneus longus (PL) and tibialis anterior (TA) are antagonists to each other as the PL plantarflexes and everts, while the TA dorsiflexes and inverts the foot. The peroneus brevis (PB) and posterior tibialis (PT) are antagonists to each other.
The cited cadaveric study by Silver found that the plantarflexors of the ankle were six times as strong as the dorsiflexors.
Silver RL, de la Garza J, Rang M.
J Bone Joint Surg Br. 1985 May;67(3):432-7. PMID: 3997956 (Link to Abstract)
Silver, BJJ 1985
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This video demonstrates the gait cycle and breaks down each basic component to h...
Biomechanics of the subtalar joint
Ankle biomechanics explains