Introduction: The pain of patellar tendinopathy (PT) may be mediated by neuronal glutamate and sodium channels. Lidocaine and tetracaine block both of these channels. This study tested the self-heated lidocaine-tetracaine patch (HLT patch) in patients with PT confirmed by physical examination to determine if the HLT patch might relieve pain and improve function.
Methods: Thirteen patients with PT pain of ≥14 days' duration and baseline average pain scores ≥4 (on a 0-10 scale) enrolled in and completed this prospective, single-center pilot study. Patients applied one HLT patch to the affected knee twice daily for 2-4 hours for a total of 14 days. Change in average pain intensity and interference (Victorian Institute of Sport Assessment [VISA]) scores from baseline to day 14 were assessed. No statistical inference testing was performed.
Results: Average pain scores declined from 5.5 ± 1.3 (mean ± standard deviation) at baseline to 3.8 ± 2.5 on day 14. Similarly, VISA scores improved from 45.2 ± 14.4 at baseline to 54.3 ± 24.5 on day 14. A clinically important reduction in pain score (≥30%) was demonstrated by 54% of patients.
Conclusion: The results of this pilot study suggest that topical treatment that targets neuronal sodium and glutamate channels may be useful in the treatment of PT.
Keywords: heated lidocaine; knee pain; patellar tendinopathy; patellar tendinosis; tetracaine patch; topical analgesic patch.