Question:hard
The classical flexion and rotation deformities at the hip and knee joints as a sequela of poliomyelitis are due to the contracture of:
The classical flexion and rotation deformities at the hip and knee joints as a sequela of poliomyelitis are due to the contracture of:
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A spared, tight tensor fasciae latae (via the iliotibial band) pulls both hip and knee into flexion with rotation in old polio cases.
Updated On: Jul 8, 2026
- Tensor fasciae latae
- Gastrocnemius
- Tendo Achilles
- Hamstrings
Show Solution
The Correct Option is A
Solution and Explanation
Step 1: Think about muscle balance after polio.
Polio does not weaken every muscle equally. Some groups are spared and stay strong, and if those spared muscles are not balanced by an opposing weak group, they slowly pull the joint into a fixed abnormal position. This kind of unopposed pull is what causes late polio deformities.
Step 2: Trace the action of each muscle in the options.
The tensor fasciae latae flexes and internally rotates the hip and, through its long iliotibial band, also drags the knee into flexion with outward rotation of the leg. The gastrocnemius and tendo Achilles mainly bend the ankle into equinus. The hamstrings mainly bend the knee.
Step 3: Match the deformity pattern in the question.
The question describes a combined flexion plus rotation deformity spanning both the hip and the knee, not just the ankle or just the knee. Only a muscle that crosses both the hip and the knee, and produces rotation as well as flexion, fits this description.
Step 4: Confirm the muscle.
The tensor fasciae latae, through the iliotibial tract, is the muscle that spans both joints and gives this exact flexion, abduction and rotation pattern in chronic polio patients.
Step 5: Conclude.
\[ \boxed{\text{Tensor fasciae latae}} \]
Polio does not weaken every muscle equally. Some groups are spared and stay strong, and if those spared muscles are not balanced by an opposing weak group, they slowly pull the joint into a fixed abnormal position. This kind of unopposed pull is what causes late polio deformities.
Step 2: Trace the action of each muscle in the options.
The tensor fasciae latae flexes and internally rotates the hip and, through its long iliotibial band, also drags the knee into flexion with outward rotation of the leg. The gastrocnemius and tendo Achilles mainly bend the ankle into equinus. The hamstrings mainly bend the knee.
Step 3: Match the deformity pattern in the question.
The question describes a combined flexion plus rotation deformity spanning both the hip and the knee, not just the ankle or just the knee. Only a muscle that crosses both the hip and the knee, and produces rotation as well as flexion, fits this description.
Step 4: Confirm the muscle.
The tensor fasciae latae, through the iliotibial tract, is the muscle that spans both joints and gives this exact flexion, abduction and rotation pattern in chronic polio patients.
Step 5: Conclude.
\[ \boxed{\text{Tensor fasciae latae}} \]
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