Metabolic and Inflammatory Indices in Lateral Epicondylitis

This study aims to investigate whether metabolic and inflammatory indices differ between patients with chronic lateral epicondylitis (tennis elbow) and individuals without the condition. It will also examine whether these indices are associated with pain severity and functional limitations in patients with lateral epicondylitis. This observational, controlled cross-sectional study will include 144 participants aged 30-65 years: 72 patients with chronic lateral epicondylitis and 72 controls without lateral epicondylitis. Metabolic and inflammatory indices will be calculated using laboratory test results obtained on the day of study enrollment as part of routine clinical care. These include fasting glucose, triglycerides, HDL cholesterol, and monocyte count. The main index will be the triglyceride-glucose (TyG) index. Additional indices will include the atherogenic index of plasma (AIP), monocyte-to-HDL cholesterol ratio (MHR), and triglyceride-glucose body mass index (TyG-BMI). Pain severity and functional limitations will be assessed using the Numeric Rating Scale (NRS) and the Patient-Rated Tennis Elbow Evaluation (PRTEE) in patients with lateral epicondylitis. Demographic characteristics, smoking status, and occupational physical demands will also be recorded.

\*\*Inclusion Criteria\*\* \*\*Lateral Epicondylitis Group:\*\* * Adults aged 25-65 years. * Lateral elbow pain lasting at least three months. * Tenderness on palpation over the lateral epicondyle. * Reproduction of familiar lateral elbow pain during resisted wrist extension with the elbow fully extended. * Availability of fasting glucose and triglyceride results obtained on the same day as part of routine clinical care. * Provision of written informed consent. \*\*Control Group:\*\* * Adults aged 25-65 years. * No history of lateral elbow pain during the preceding 12 months. * Negative findings on lateral epicondyle palpation and resisted wrist extension testing. * Availability of fasting glucose and triglyceride results obtained on the same day as part of routine clinical care. * Provision of written informed consent. \*\*Exclusion Criteria (Both Groups):\*\* * Diabetes mellitus or use of glucose-lowering medications. * Use of lipid-lowering medications. * Systemic inflammatory or rheumatological disease. * Active infection, malignancy, or advanced renal or hepatic disease. * Uncontrolled thyroid disease. * Pregnancy. * Use of systemic corticosteroids or immunosuppressive medications. * Previous elbow surgery or major elbow trauma. * Cervical radiculopathy, peripheral nerve entrapment, elbow arthritis, or another condition that could explain lateral elbow pain. * Injection or extracorporeal shock wave therapy (ESWT) to the lateral epicondyle within the preceding three months.