This post comes from Fred Nelson, MD, an orthopaedic surgeon in the Department of Orthopedics at Henry Ford Hospital and a clinical associate professor at Wayne State Medical School. Some of Dr. Nelson’s tips go out weekly to more than 3,000 members of the Orthopaedic Research Society (ORS), and all are distributed to more than 30 orthopaedic residency programs. Those not sent to the ORS are periodically reposted in OrthoBuzz with the permission of Dr. Nelson.
The effects of electrical currents on early wound healing are well known and studied. The possibility that stimulation of bone formation could be induced with a pulsed electromagnetic field (PEMF) was investigated in the 1960s and translated into clinical use by the 1970s. But the clinical use of PEMF for tendon disorders has not met with similar success.
The precise mechanisms by which these fields affect different tissues is easier to study with the tools we have available today. The measurable parameters of PEMF are intensity, duration, frequency, and duty cycle (percent of time the field is on). Nevertheless, many questions about the possible adverse effects of these fields, their focal delivery, and their possible clinical applications remain unanswered.
In a study of human tendon cells, researchers artificially induced inflammatory cues in cultures using different concentrations of IL‐1β.1 When 1 ng/mL of IL‐1β was used, subsequent cytokine and metalloprotease expression was measured at 1, 2, 3, and 7 days after various PEMF exposures.
The PEMF exposure parameters that most evidently decreased the production of IL-6 and tumor necrosis factor-α (TNF-α) were 4 mT, 5 Hz, and a 50% duty cycle. Those same parameters decreased the expression of TNFα, IL-6, IL-8, COX-2, MMP-1, MMP-2, and MMP-3, while at the same time increasing gene expression of the anti-inflammatory proteins IL-4, IL-10, and TIMP-1. However, the combination of 5 mT and 50% duty cycle had a negative impact on cell viability.
These preliminary results may help guide future investigations, but the authors note that the parameters for optimal PEMF effectiveness on tendon cells may vary with time from insult, further complicating the selection of field parameters.
- Vinhas A, Rodrigues MT, Gonçalves AI, Reis RL, Gomes ME. Pulsed Electromagnetic Field Modulates Tendon Cells Response in IL-1β-Conditioned Environment. J Orthop Res. 2020 Jan;38(1):160-172. doi: 10.1002/jor.24538. Epub 2019 Dec 10.
Fluoroquinolone antibiotics do a great job fighting a broad spectrum of bacteria that cause many respiratory, urogenital, gastrointestinal, and bone and joint infections. However, in 2008, the FDA issued a “black-box warning” about the increased risk of tendinopathies in people taking these drugs, especially those older than 60.
Although rare, when fluoroquinolone-induced tendon ruptures occur, they involve the Achilles tendon 95% of the time. But in the April 8, 2015 edition of JBJS Case Connector, DeWolf et al. describe the case of an 81-year-old man whose sudden inability to extend the metacarpophalangeal joint of his ring finger occurred within one week after he started taking the fluoroquinolone ciprofloxacin for an ear infection.
In the OR, surgeons identified and debrided a ruptured extensor digitorum communis (EDC) tendon and attached it to the EDC of the adjacent middle finger. They found no bony protrusions or synovitis that could have caused tendon erosion, and cultures for bacterial and fungal infections came back negative. Those negative findings, combined with the patient’s medication history and lack of other risk factors such as gout or rheumatoid arthritis, led the authors to postulate with some certainty that ciprofloxacin was the etiological culprit.
DeWolf et al. remind orthopaedists that for general tendinopathy, “the mainstays of treatment include rest, physical therapy, and discontinuation of [any] offending medication.” Ruptured tendons are usually addressed surgically. Although the authors do not report having taken ultrasound images of this patient, they note that “ultrasound provides an inexpensive way to confirm that a tendon has been ruptured and also whether it is a partial or complete rupture.”