chronic ankle instability could be associated with some proximal deficits as in hip and knee regions. these deficits include alternations in motor neurons pools excitability, muscle strength, kinematics and kinetics. this study add muscle inflexibility to the preciouse literature.

Background: influence of a localized injury in a distal joint on the function of proximal muscles is an important consideration in assessment and treatment of musculoskeletal injuries. Up to the investigator's knowledge, there is no study assess flexibility changes in CAI. Objectives: The objective of this study is to investigate Hamstring flexibility in CAI. Material and methods: The study conducted on 42 subjects with unilateral CAI and controls had measure of hamstring flexibility using digital inclinometer during passive knee extension test .Results: Revealed statistical and clinical significant difference between non-injured control group and CAI group with decreased hamstring flexibility in the later. Conclusion: CAI subjects have proximal muscular affection include hamstring tightness which may alter sacroiliac joint stability and subsequently back pain.

Inclusion Criteria:

• The control group was self-reported to be healthy
• Had no ankle injury history
• Matched with CAI patients in gender, dominance side and simulated injured side
• CAI group had a self-report of a past history of unilateral ankle inversion injury since at least more than 1 year before the study onset which required a period of protected weight bearing and/or immobilization at least one day
• Patient reported a tendency for the ankle to give way and/or recurrent ankle sprain
• Perceives that the ankle was chronically weaker, more painful and/or less functional than the other ankle or than before first

Exclusion Criteria:

• Had a history of lower extremity injury
• Surgery or fracture
• History of low back dysfunction that required medical or surgical intervention within the last year, Current participation in formal or informal rehabilitation
• History of hamstring strain
• Bilateral ankle sprain injury
• Ankle injury within 3 months of participation
• History of ankle fracture and any neuromuscluskeletal disease could affect the condition.

Outpatients clinic faculty of physical therapy Cairo university

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