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

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

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 Overview

• Status: Recruiting
• Conditions: Tennis Leg; Muscle Contusion
• Intervention / Treatment: Diagnostic test: B-mode Diagnostic Ultrasound - Scar Tissue Assessment; Diagnostic test: Isokinetic Dynamometry - Eccentric Plantar Flexor Strength Assessment

• Study Type: Observational
• Enrollment (Estimated): 40

Contacts and Locations

• Study Contact: Name: Mohamed M ElMeligie, Ph.D; Phone Number: 01159880001; Email: mohamed.elmeligie@acu.edu.eg

Study Locations

• Egypt
  • Cairo Governorate
    • New Cairo, Cairo Governorate, Egypt, 12345
      • Recruiting
      • Outpatient clinic of faculty of physical therapy, Alhayah University in Cairo
      • Contact: Mohamed M ElMeligie, Ph.D; Phone Number: 01159880001; Email: mohamed.elmeligie@acu.edu.eg
      • Principal Investigator: Mariam A Wagdy, BSc.
      • Principal Investigator: Haitham M Elhafez, PhD

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: No

• Sampling Method: Non-Probability Sample

Study Population

Patients referred from orthopedic clinics to physiotherapy clinics and/or sports rehabilitation centers in Cairo, Egypt, who have a history of unilateral medial gastrocnemius muscle tear (tennis leg) confirmed by diagnostic ultrasound, have completed acute healing (≥3 months post-injury), and have returned to daily activities.

Description

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

Study Plan

How is the study designed?

Number of groups / cohorts

1

Cohorts and Interventions

Group / Cohort

Intervention / Treatment

Tennis Leg Patients - Post-Healing; Adults aged 18-40 years with a history of unilateral medial gastrocnemius muscle tear (tennis leg, Grade I or Grade II), confirmed by ultrasound, at least 3 months post-injury, who have clinically healed and returned to daily activities. Each participant serves as their own control with the contralateral uninjured limb used for comparison.

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 intervention.; 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.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Eccentric 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.	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).	Single assessment at the time of enrollment (one study visit)

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
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.	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.	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.	Single assessment at the time of enrollment (one study visit)

Collaborators and Investigators

• Sponsor: Al Hayah University In Cairo
• Collaborators: Cairo University
• Investigators: Study Chair: Haitham M. ElHafez, Ph.D, Cairo University; Study Director: Aya A Said, Ph.D, Cairo University

Study record dates

Study Major Dates

• Study Start (Estimated): April 15, 2026
• Primary Completion (Estimated): August 15, 2026
• Study Completion (Estimated): August 15, 2026

Study Registration Dates

• First Submitted: March 31, 2026
• First Submitted That Met QC Criteria: March 31, 2026
• First Posted (Actual): April 7, 2026

Study Record Updates

• Last Update Posted (Actual): April 7, 2026
• Last Update Submitted That Met QC Criteria: March 31, 2026
• Last Verified: March 1, 2026

More Information

Terms related to this study

• Other Study ID Numbers: CUPT-MSc-2026-MARIAMAW-001

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No