The goal of this study is to improve understanding of tendon health and disease by using surplus tendon tissue that is routinely removed during planned orthopaedic surgeries in adults. The main questions it aims to answer are:

- What can tendon tissue and tendon cells tell us about how healthy and diseased tendons function?

Participants will not undergo any extra procedures. Instead, researchers will use only tissue that is already being removed as part of normal surgical care and would otherwise be discarded.

Participants will:

• Be asked for permission (consent) before their surgery to donate any surplus tendon tissue.
• Have a small piece of tendon tissue (normally waste material) collected during their planned operation.
• Allow the research team to access some non-identifiable medical information (such as age, reason for surgery, and relevant medical history) to help interpret research findings.

What the researchers will do with the donated tissue:

• Isolate different types of human tendon cells.
• Build advanced laboratory cellular models to study how tendon diseases develop.
• Analyse whole tendon tissue sections to understand cell types, tissue organisation, and disease-related changes.

This study does not involve testing treatments, and it does not change any aspect of a participant's clinical care. Although there is no direct benefit to participants, the donated tissue may help researchers develop better ways to study tendon injuries and improve future treatment options for tendon disease.

This study aims to improve our understanding of how human tendons work, why they become injured, and how tendon diseases develop. Tendon problems-such as tendinopathy-are common and can cause long-lasting pain and loss of mobility. Scientists currently lack good laboratory models that accurately represent real human tendon tissue, which makes it harder to study these conditions or test new treatments.

During many types of planned orthopaedic surgery, small pieces of tendon tissue are routinely removed because they are no longer needed for the patient's care. Normally, this tissue would simply be thrown away. In this study, patients who are already having surgery are invited to donate this surplus tissue for research.

How the study works:

If a patient agrees to take part, the healthcare team will collect the leftover tendon tissue during their planned operation. There are no extra procedures, no changes to the surgery, and nothing additional that the patient needs to do.

After collection, the tissue is taken to research laboratories at Queen Mary University of London. There, scientists use it in two main ways:

1. Studying the tendon tissue itself:

   Researchers examine the structure and cells within the tendon to study how tendon cells are organised.

2. Growing tendon cells in the lab:

The donated tissue allows researchers to isolate living tendon cells. These cells can then be used to build more advanced laboratory models-such as "tendon-on-a-chip" systems-that mimic how tendons experience movement, load, and interaction with other cell types. These models will help scientists study disease processes and could support the development of new treatments in the future.

To support this work, the research team also receives a small amount of non-identifiable medical information about each donor-such as age, general health information, and the reason for surgery. This helps researchers understand how different factors may influence tendon biology. All personal details (like names or NHS numbers) remain within the hospital and are never shared with the research team.

Why this research matters:

Human tendon tissue is rarely available for research, yet it is essential for creating accurate models and understanding real-world disease. By using tissue that would otherwise be discarded, this study will:

• Provide new insights into how tendons function and how tendon diseases develop.
• Help researchers design more realistic laboratory systems to study tendon conditions.
• Support future work aiming to improve diagnosis, prevention, and treatment of tendon disorders.

Although participants will not directly benefit, their donated tissue may contribute to scientific progress that improves care for people with tendon injuries in the future.

Inclusion Criteria:

• 18 years or older
• Scheduled to undergo orthopaedic lower limb surgery that involve tendon tissue waste
• Have provided informed consent to take part in the study

Exclusion Criteria:

• Under the age of 18
• Unable or unwilling to give informed consent (including those with limited English proficiency)
• Cases where tendon tissue is required for clinical care and therefore not surplus.

Patients scheduled to undergo orthopaedic lower limb surgery at the Royal London, Whipps Cross University Hospital and the Barts Health Orthopaedic Centre in Newham.

No individual participant data will be shared. All data used in the study are pseudonymised before transfer to the research team, and identifiable information remains within the NHS clinical environment. No IPD dataset suitable for external sharing will be generated.