Residual Eccentric Strength Deficits and Deep Scar Tissue Thickness in Patients With Tennis Leg

Official title

Residual Eccentric Strength Deficits of Gastrocnemius Muscle and Deep Scar Tissue Thickness in Patients With Tennis Leg: A Cross-Sectional Study

Overview

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.

Interventions

• Diagnostic test B-mode Diagnostic Ultrasound - Scar Tissue Assessment
  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 intervent
• Diagnostic test Isokinetic Dynamometry - Eccentric Plantar Flexor Strength Assessment
  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.

Primary outcome measures

• Eccentric Plantar Flexor Strength Deficit (Percentage) [Time frame: Single assessment at the time of enrollment (one study visit)]
• Deep Scar Tissue Thickness (millimeters) [Time frame: Single assessment at the time of enrollment (one study visit)]

Secondary outcome measures (3)

• Single-Leg Heel Raise Endurance [Time frame: Single assessment at the time of enrollment (one study visit)]
• Time-to-Fatigue During Repeated Plantar Flexion [Time frame: Single assessment at the time of enrollment (one study visit)]
• Ankle Dorsiflexion Range of Motion [Time frame: Single assessment at the time of enrollment (one study visit)]

Eligibility criteria

Inclusion criteria

• Age between 18 and 40 years
• History of unilateral plantar flexor muscle tear (tennis leg) involving the medial gastrocnemius, confirmed by diagnostic ultrasound
• Ultrasound diagnostic criteria: hypoechoic or anechoic fluid collection between the medial gastrocnemius and soleus muscles, with partial or complete disruption of the normal muscle fiber architecture at the myotendinous junction
• Grade I (mild strain, <10% fiber involvement) or Grade II (moderate partial tear, 10-90% fiber involvement) injury
• At least 3 months post-injury
• Clinically healed with return to daily activities
• Ability to perform maximal eccentric plantar flexion as assessed by the Eccentric Heel Raise Test (Single-Leg) (Chen et al., 2009)

Exclusion criteria

• Bilateral calf injuries
• Grade III (severe/complete) gastrocnemius muscle rupture
• Previous Achilles tendon rupture or surgery
• Previous injuries or surgeries to the lower extremity (other than the index tennis leg injury)
• Neurological disorders affecting lower limb function
• Current acute pain or re-injury at the time of assessment
• Other lower-limb musculoskeletal injuries affecting performance
• Systemic inflammatory or connective tissue diseases
• Popliteal cyst rupture
• Deep vein thrombosis
• Isolated Achilles tendon rupture
• Muscle tumor

Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.

Healthy volunteers: No

Study design

Observational model

Other

Study locations

Egypt · 1 center

• Outpatient clinic of faculty of physical therapy, Alhayah University in Cairo — New Cairo

Identifiers

NCT: NCT07513779 · CUPT-MSc-2026-MARIAMAW-001

Primary sources (government registries)

• ClinicalTrials.gov (US NIH)

View this study on ClinicalTrials.gov ↗