Objectives: To identify risk factors for failure of a therapeutic injection leading to operative management of both medial and lateral epicondylitis.
Methods: A national database was used to query Medicare Standard Analytic Files from 2005-2012 for patients treated with therapeutic injections for medial or lateral epicondylitis using CPT codes for injections associated with corresponding ICD-9 diagnostic codes (726.31 and 726.32, respectively). Those who subsequently underwent surgical treatment following injection were identified. A multivariate binomial logistic regression analysis was utilized to evaluate patient-related risk factors for requiring surgery within 2 years after therapeutic injection.
Results: 1,837 patients received therapeutic injections for medial epicondylitis. 52 (2.8%) required ipsilateral surgery at a mean of 429 ± 28 days post-injection. Risk factors for requiring surgical intervention included age <65, obesity, and morbid obesity. 6,561 patients received therapeutic injections for lateral epicondylitis. 201 (3.1%) required subsequent surgery at a mean of 383 ± 128 days' post-injection. Risk factors included age <65, tobacco use, diabetes mellitus and peripheral vascular disease.
Conclusion: The incidence of surgical intervention following a failed therapeutic injection for medial or lateral epicondylitis is low (~3%). Risk factors for failing a therapeutic injection include age <65 years and obesity (BMI > 30) for medial epicondylitis and age <65 years, smoking, diabetes mellitus and peripheral vascular disease for lateral epicondylitis. Patients with these identified risk factors presenting with medial or lateral epicondylitis should be cautioned that they carry a higher risk of subsequent surgical treatment.
Level of evidence: Therapeutic, III.
Keywords: Lateral epicondylitis; failure; injection; medial epicondylitis; risk factors.