Anterior Knee Pain and Patellar Tendon Elasticity After Infrapatellar Tendon-Split Tibial Intramedullary Nailing

Relationship Between Anterior Knee Pain and Patellar Tendon Elasticity After Infrapatellar Tendon-Split Tibial Intramedullary Nailing: A Prospective Cohort Study Using Shear-Wave Ultrasound Elastography

This prospective single-center observational cohort study will evaluate the relationship between anterior knee pain and patellar tendon elasticity after infrapatellar tendon-split tibial intramedullary nailing. Adult patients undergoing standard tibial intramedullary nailing through an infrapatellar tendon-split approach will be enrolled after ethics approval. Patellar tendon elasticity will be assessed using shear-wave ultrasound elastography before surgery and during follow-up at 6 weeks, 3 months, and 6 months. Clinical outcomes will include anterior knee pain severity, patellofemoral function, tendon-related symptoms, and knee range of motion. Inter-rater reliability between two independent radiologists will also be evaluated.

Study Overview

• Status: Active, not recruiting
• Conditions: Anterior Knee Pain; Tibial Shaft Fractures; Patellar Tendon Disorder
• Intervention / Treatment: Procedure: Infrapatellar tendon-split tibial intramedullary nailing; Diagnostic test: Shear-wave ultrasound elastography

Detailed Description

Anterior knee pain is a frequent complaint after tibial intramedullary nailing, but the role of patellar tendon biomechanical changes remains unclear. The infrapatellar tendon-split approach may lead to tendon healing, remodeling, and fibrosis, which could alter tendon elasticity and contribute to persistent pain and functional limitation. This study aims to prospectively investigate whether changes in patellar tendon elasticity are associated with anterior knee pain after infrapatellar tendon-split tibial intramedullary nailing.

This is a prospective, single-center, non-interventional observational cohort study. Adult patients aged 18 to 65 years with unilateral tibial shaft or metaphyseal fractures treated with standard infrapatellar tendon-split tibial intramedullary nailing will be enrolled consecutively after institutional ethics approval. Only patients enrolled after ethics approval will be included in the registered cohort.

Patellar tendon elasticity will be measured using shear-wave ultrasound elastography at four predefined time points: preoperatively, 6 weeks, 3 months, and 6 months postoperatively. Ultrasound assessments will be performed according to a standardized protocol by two independent radiologists, and inter-rater reliability will be assessed. Additional ultrasound parameters will include tendon thickness on B-mode imaging and Doppler neovascularization.

Clinical outcomes will include anterior knee pain assessed with a visual analog scale, patellofemoral function assessed with the Kujala Anterior Knee Pain Scale, tendon-related symptoms assessed with the VISA-P questionnaire, pressure pain sensitivity, and active knee range of motion. The primary objective is to determine whether change in patellar tendon elasticity is associated with anterior knee pain at 6 months. Secondary objectives are to examine associations between tendon elasticity and functional scores, range of motion, tendon thickness, Doppler findings, and inter-rater measurement reliability.

• Study Type: Observational
• Enrollment (Estimated): 50

Contacts and Locations

Study Locations

• Turkey (Türkiye)
  • Istanbul
    • Istanbul, Istanbul, Turkey (Türkiye), 34320
      • Bagcilar Training and Research Hospital

Participation Criteria

Eligibility Criteria

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

• Sampling Method: Non-Probability Sample

Study Population

Adults with unilateral tibial shaft or metaphyseal fractures treated at Bagcilar Training and Research Hospital with standard infrapatellar tendon-split tibial intramedullary nailing will be enrolled prospectively after ethics approval.

Description

Inclusion Criteria:

• Age 18 to 65 years
• Unilateral tibial shaft or metaphyseal fracture
• Planned treatment with infrapatellar tendon-split tibial intramedullary nailing
• Ability to complete baseline and follow-up assessments
• Written informed consent

Exclusion Criteria:

• Previous surgery on the same knee
• Previous patellar tendon rupture or known patellar tendon disorder
• Active inflammatory rheumatologic disease
• Chronic systemic corticosteroid therapy or long-term immunosuppressive treatment
• Significant peripheral neuropathy or advanced diabetic neuropathy
• Bilateral tibial fracture
• Additional major lower-extremity injury or surgery affecting assessment
• Inability to comply with scheduled follow-up visits

Study Plan

How is the study designed?

Number of groups / cohorts

1

Cohorts and Interventions

Group / Cohort

Intervention / Treatment

Infrapatellar Tendon-Split Tibial Nailing Cohort; Adult patients with unilateral tibial shaft or metaphyseal fractures treated with standard infrapatellar tendon-split tibial intramedullary nailing after ethics approval. Participants will be followed prospectively with shear-wave ultrasound elastography and clinical assessments at baseline, 6 weeks, 3 months, and 6 months.

Procedure: Infrapatellar tendon-split tibial intramedullary nailing; Standard-of-care tibial intramedullary nailing performed through an infrapatellar longitudinal patellar tendon split approach. The procedure is not assigned by the protocol; only patients undergoing this routine surgical approach are observed.; Diagnostic test: Shear-wave ultrasound elastography; Non-invasive shear-wave ultrasound elastography of the patellar tendon performed at predefined study visits using a standardized imaging protocol.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in patellar tendon elasticity from baseline to 6 months	Patellar tendon elasticity measured by shear-wave ultrasound elastography in kilopascals. The primary analysis will assess the longitudinal change from baseline to 6 months.	Preoperative baseline and 6 months postoperatively

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in patellar tendon elasticity from baseline to 3 months	Change in patellar tendon elasticity measured by shear-wave ultrasound elastography.	Preoperative baseline and 3 months postoperatively
Anterior knee pain severity	Anterior knee pain severity will be assessed using the Visual Analog Scale. The Visual Analog Scale ranges from 0 to 10, where 0 indicates no pain and 10 indicates the worst imaginable pain. Higher scores indicate worse anterior knee pain.	Baseline and postoperative 6 weeks, 3 months, and 6 months
Patellofemoral function	Patellofemoral function will be assessed using the Kujala Anterior Knee Pain Scale. The scale ranges from 0 to 100 points, with higher scores indicating better patellofemoral function and fewer anterior knee symptoms.	Preoperative baseline, 3 months, and 6 months
Patellar Tendon-Related Symptoms and Function	Patellar tendon-related symptoms and function will be assessed using the Victorian Institute of Sport Assessment-Patella questionnaire. The questionnaire ranges from 0 to 100 points, with higher scores indicating fewer patellar tendon-related symptoms and better function	Preoperative baseline, 3 months, and 6 months
Active knee range of motion	Active knee flexion and extension lag measured with a goniometer.	Preoperative baseline, 6 weeks, 3 months, and 6 months
Patellar tendon thickness	Patellar tendon thickness measured on B-mode ultrasound.	Preoperative baseline, 6 weeks, 3 months, and 6 months
Doppler neovascularization	Semiquantitative Doppler neovascularization score.	Preoperative baseline, 6 weeks, 3 months, and 6 months
Pressure Pain Sensitivity	Pressure pain sensitivity will be assessed by recording pain intensity during a standardized pressure pain assessment using the Visual Analog Scale. The Visual Analog Scale ranges from 0 to 10, where 0 indicates no pain and 10 indicates the worst imaginable pain. Higher scores indicate greater pressure pain sensitivity.	6 weeks, 3 months, and 6 months
Inter-rater reliability of shear-wave elastography measurements	Agreement between two independent radiologists assessed using intraclass correlation coefficients.	Baseline, 6 weeks, 3 months, and 6 months

Collaborators and Investigators

• Sponsor: Bagcilar Training and Research Hospital

Study record dates

Study Major Dates

• Study Start (Actual): March 5, 2026
• Primary Completion (Estimated): November 30, 2026
• Study Completion (Estimated): December 31, 2026

Study Registration Dates

• First Submitted: June 15, 2026
• First Submitted That Met QC Criteria: June 17, 2026
• First Posted (Actual): June 22, 2026

Study Record Updates

• Last Update Posted (Actual): June 22, 2026
• Last Update Submitted That Met QC Criteria: June 17, 2026
• Last Verified: June 1, 2026

More Information

Terms related to this study

• Keywords: Anterior knee pain; Tibial shaft fracture; Shear-wave elastography; Tibial intramedullary nailing; Infrapatellar tendon split; Patellar tendon elasticity
• Other Study ID Numbers: BEA-ORT-MYY-01

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: Individual participant data will not be shared because this is a single-center study with a limited sample size and no predefined external data-sharing agreement. Only aggregate, de-identified study results will be reported in publications and presentations.

Drug and device information, study documents

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