This study investigates the relationship between the thickness of deep scar tissue and residual weakness in the calf muscles of patients who have recovered from a condition known as "tennis leg." Tennis leg is a common calf muscle injury caused by a partial tear of the inner part of the gastrocnemius (calf) muscle at the point where muscle meets tendon. While patients often return to daily activities after healing, many continue to experience hidden weakness in their calf muscles, particularly during activities that require the muscle to lengthen under load (eccentric contractions), such as walking downhill, running, or landing from a jump. This study uses diagnostic ultrasound imaging to measure the thickness of scar tissue that forms inside the muscle after injury. It also uses an isokinetic dynamometer to objectively measure the eccentric (lengthening) strength of the calf muscles. By comparing the injured leg to the uninjured leg in the same person, the study determines whether patients with thicker scar tissue have greater residual strength deficits. The study enrolls adults aged 18 to 40 years who have had a confirmed unilateral calf muscle tear at least 3 months ago and have returned to normal daily activities. No treatment or intervention is provided. All assessments are performed at a single time point. Understanding how scar tissue relates to persistent muscle weakness could help clinicians better predict long-term outcomes, design more effective rehabilitation programs, and make more informed decisions about when patients are ready to return to sport and physical activity.
Study Type
OBSERVATIONAL
Enrollment
40
B-mode diagnostic ultrasound is used to measure deep scar tissue thickness (in millimeters) at the musculotendinous junction of the medial gastrocnemius muscle. Measurements are obtained in both longitudinal and transverse planes at the site of maximal scar thickness. The contralateral uninjured limb is measured for comparison. Assessments are performed by a blinded experienced sonographer using a standardized probe position. This is a diagnostic exposure measurement, not a therapeutic intervention.
Eccentric plantar flexor strength is assessed using an isokinetic dynamometer at angular velocities of 30°/s and 60°/s. Peak torque (Nm) is recorded for both the injured and uninjured limbs. Testing follows a standardized warm-up protocol with randomized testing order and adequate rest between trials. The percentage deficit between limbs is calculated. This is a diagnostic measurement, not a therapeutic intervention.
Outpatient clinic of faculty of physical therapy, Alhayah University in Cairo
New Cairo, Cairo Governorate, Egypt
RECRUITINGEccentric Plantar Flexor Strength Deficit (Percentage)
The percentage difference in eccentric peak torque (Nm) of the plantar flexor muscles between the injured and uninjured limbs, measured using isokinetic dynamometry at 30°/s and 60°/s. Deficit is calculated as: \[(Uninjured - Injured) / Uninjured\] × 100. A higher percentage indicates greater residual weakness.
Time frame: Single assessment at the time of enrollment (one study visit)
Deep Scar Tissue Thickness (millimeters)
Maximal thickness of deep scar tissue at the musculotendinous junction of the medial gastrocnemius muscle, measured in millimeters using B-mode diagnostic ultrasound in longitudinal and transverse planes. Measurements are compared with the contralateral uninjured limb. Additional scar characteristics recorded include echogenicity (hypoechoic/mixed/hyperechoic), scar continuity and alignment, presence of adhesions, and pennation angle disruption (if visible).
Time frame: Single assessment at the time of enrollment (one study visit)
Single-Leg Heel Raise Endurance
Number of single-leg heel raise repetitions performed on each limb until fatigue. Heel raise height symmetry between limbs is also recorded.
Time frame: Single assessment at the time of enrollment (one study visit)
Time-to-Fatigue During Repeated Plantar Flexion
Time (in seconds) to fatigue during repeated single-leg plantar flexion for both the injured and uninjured limbs.
Time frame: Single assessment at the time of enrollment (one study visit)
Ankle Dorsiflexion Range of Motion
Passive ankle dorsiflexion range of motion (degrees) measured using a standard universal goniometer, assessing the angle between the foot and tibia in a standardized position. Restricted dorsiflexion may indicate increased stiffness or altered tissue elasticity due to scar tissue. Measured bilaterally.
Time frame: Single assessment at the time of enrollment (one study visit)
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