Effects of Clamshell Exercises in Addition to Standardized Physical Therapy in the Management of Patellofemoral Pain Syndrome

NCT07730437 | Completed DMC

• 1 other identifier: IIUI/RERC/ADT/2026/O2/229
• Study Type: interventional
• Target: 40
• Locations: 1 country
• Sites: 1

Brief Summary

This randomized controlled trial aims to evaluate whether adding clamshell exercises to standardized physical therapy provides greater improvements in pain and knee function than standardized physical therapy alone in individuals with patellofemoral pain syndrome (PFPS). PFPS is a common musculoskeletal condition characterized by pain around or behind the kneecap that is aggravated by activities such as stair climbing, squatting, running, and prolonged sitting. Participants aged 18-45 years with clinically diagnosed PFPS will be randomly assigned to one of two groups. The control group will receive standardized physical therapy consisting of warm-up exercises, stretching, quadriceps and lower-limb strengthening exercises, and cool-down activities. The experimental group will receive the same standardized physical therapy program with the addition of clamshell exercises targeting the gluteus medius and hip external rotator muscles. Both groups will participate in supervised treatment sessions lasting approximately 45 minutes, three times per week, for four weeks. Pain intensity will be measured using the Numeric Pain Rating Scale (NPRS), and knee function will be assessed using the Kujala Anterior Knee Pain Scale before and after the intervention. The findings of this study may help determine whether incorporating clamshell exercises into routine physiotherapy improves rehabilitation outcomes for patients with PFPS.

Conditions

Patellofemoral Pain Syndrome; Anterior Knee Pain

Keywords

Patellofemoral Pain Syndrome (PFPS); Anterior Knee Pain; Clamshell Exercise; Hip Abductor Strengthening

Outcome Measures

Primary Outcomes (1)

• Change in Pain Intensity Measured by the Numeric Pain Rating Scale (NPRS)

  Pain intensity will be assessed using the 11-point Numeric Pain Rating Scale (NPRS), where 0 indicates no pain and 10 indicates the worst imaginable pain. The primary outcome is the change in NPRS score from baseline to the end of the intervention.

  Baseline and Week 4 (end of intervention)

Secondary Outcomes (1)

• Change in Knee Function Measured by the Kujala Anterior Knee Pain Scale

  Baseline and Week 4 (end of intervention)

Study Arms (2)

Standardized Physical Therapy (Control)

EXPERIMENTAL

Participants will receive standardized physical therapy consisting of warm-up exercises, stretching, quadriceps and lower-limb strengthening exercises, and cool-down activities. Each treatment session will last approximately 35 minutes, three times per week for four weeks.

Behavioral: Standardized Physical Therapy

Standardized Physical Therapy + Clamshell Exercises

EXPERIMENTAL

Participants will receive standardized physical therapy together with side-lying clamshell exercises targeting the gluteus medius and hip external rotator muscles. Treatment sessions will last approximately 45 minutes, three times per week for four weeks. The only additional intervention compared with the control group is the inclusion of clamshell exercises.

Behavioral: Standardized Physical Therapy with Clamshell Exercise

Interventions

Standardized Physical Therapy BEHAVIORAL

Standardized physical therapy consists of warm-up exercises, stretching of the hamstrings, quadriceps, gastrocnemius-soleus, and iliotibial band, quadriceps and lower-limb strengthening exercises (including static quadriceps exercises, straight leg raises, hip strengthening exercises, and mini-squats), followed by cool-down stretching. The control group receives this intervention for approximately 35 minutes per session, three sessions per week for four weeks.

Also known as: Conventional Physiotherapy

Standardized Physical Therapy (Control)

Standardized Physical Therapy with Clamshell Exercise BEHAVIORAL

Participants perform side-lying clamshell exercises to strengthen the gluteus medius and hip external rotator muscles. The exercise is performed as 3 sets of 12-15 repetitions under physiotherapist supervision. This intervention is added to standardized physical therapy in the experimental group, resulting in a total treatment time of approximately 45 minutes per session, three sessions per week for four weeks.

Also known as: Side-lying Clamshell Exercise

Standardized Physical Therapy + Clamshell Exercises

Eligibility Criteria

• Age: 18 Years - 45 Years
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64)

You may qualify if:

• Adults aged 18 to 45 years. Male or female participants. Clinically diagnosed with patellofemoral pain syndrome (PFPS) according to the American Physical Therapy Association (APTA) clinical practice guidelines.
• Presence of retropatellar or peripatellar pain. Reproduction of retropatellar or peripatellar pain during squatting or other functional activities that load the patellofemoral joint in knee flexion.
• Symptoms present for at least 3 months. Pain intensity of ≥3 on the Numeric Pain Rating Scale (NPRS) during aggravating activities.
• Able and willing to provide written informed consent and comply with the study procedures.

You may not qualify if:

• History of knee surgery, ligament injury, meniscal tear, patellar dislocation, or knee osteoarthritis.
• Lumbar radiculopathy, hip pathology, or systemic inflammatory arthritis (e.g., rheumatoid arthritis).
• Corticosteroid injection or knee surgery within the previous 3 months. Neuromuscular disorders affecting muscle function (e.g., stroke or Parkinson's disease).
• Pregnancy or within 6 months postpartum. Family history of early degenerative joint disease. Any condition that, in the investigator's opinion, would interfere with safe participation or completion of the study.

Sponsors & Collaborators

• Ibadat International University, Islamabad: lead

Study Sites (1)

Tahir general Hospital Charsadda

Charsadda, KPK, 24420, Pakistan

Location

Related Publications (1)

• Neal BS, Lack SD, Lankhorst NE, Raye A, Morrissey D, van Middelkoop M. Risk factors for patellofemoral pain: a systematic review and meta-analysis. Br J Sports Med. 2019;53(5):270-81. 2. Lack S, Barton C, Sohan O, Crossley K, Morrissey D. Proximal muscle rehabilitation is effective for patellofemoral pain: a systematic review with meta-analysis. Br J Sports Med.2015;49(21):1365-76. 3. Rathleff MS, Roos EM, Olesen JL, Rasmussen S. Exercise during school hours when added to patient education improves outcome for 2 years in adolescent patellofemoral pain: a cluster randomised trial. Br J Sports Med. 2015;49(6):406-12. 4. Bolgla LA, Boling MC. An update for the conservative management of patellofemoral pain syndrome: a systematic review of the literature from 2000 to 2010. Int J Sports Phys Ther. 2011;6(2):112-25. 5. Powers CM. The influence of abnormal hip mechanics on knee injury: a biomechanical perspective. J Orthop Sports Phys Ther. 2010;40(2):42-51. 6. Ferber R, Bolgla L, Earl-Boehm JE, Emery C, Hamstra-Wright K. Strengthening of the hip and core versus knee muscles for the treatment of patellofemoral pain: a multicenter randomized controlled trial. J Athl Train. 2015;50(4):366-77. 7. Khayambashi K, Fallah A, Movahedi A, Bagwell J, Powers C. Posterolateral hip muscle strengthening versus quadriceps strengthening for patellofemoral pain: a comparative control trial. Arch Phys Med Rehabil. 2014;95(5):900-7. 8. Santos TR, Oliveira BA, Ocarino JM, Holt KG, Fonseca ST. Effectiveness of hip muscle strengthening in patellofemoral pain syndrome patients: a systematic review. Braz J Phys Ther. 2015;19(3):167-76. 9. Kamel AM, Ghuiba K, Abd Allah DS, Fayaz NA, Abdelkader NA. Effect of adding short foot exercise to hip and knee focused exercises in treatment of patients with patellofemoral pain syndrome: a randomized controlled trial. J Orthop Surg Res. 2024;19(1):207. 10. Alammari A, Spence N, Narayan A, Karnad SD, Ottayil ZC. Effect of hip abductors and lateral rotators' mu

  RESULT

MeSH Terms

Conditions

Patellofemoral Pain Syndrome

Condition Hierarchy (Ancestors)

Joint Diseases; Musculoskeletal Diseases

Study Officials

• Dr Muhammad Nazim Farooq Dean, Phd

  Ibadat International University, Islamabad

  PRINCIPAL INVESTIGATOR

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: SINGLE
• Who Masked: OUTCOMES ASSESSOR
• Masking Details: This is a single-blind randomized controlled trial. The outcome assessor will be blinded to treatment allocation to minimize assessment bias. Due to the nature of the exercise interventions, the treating physiotherapist cannot be blinded. Participants will not be informed of the study hypothesis or comparative purpose of the interventions, although complete blinding of participants is not feasible.
• Purpose: TREATMENT
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: SPONSOR

Model Details: Participants will be randomly assigned to one of two parallel groups. The control group will receive standardized physical therapy for 35 minutes per session, while the experimental group will receive standardized physical therapy plus clamshell exercises for a total of 45 minutes per session. Both groups will attend supervised treatment sessions three times per week for four weeks. Outcomes will be compared between groups at baseline and after completion of the intervention.

Study Record Dates

• First Submitted: July 23, 2026
• First Posted: July 28, 2026
• Study Start: January 10, 2026
• Primary Completion: May 30, 2026
• Study Completion: June 10, 2026
• Last Updated: July 28, 2026

Record last verified: 2026-07

Data Sharing

• IPD Sharing: Will not share

Locations

PA (1)