Is it safe? Local anesthetic injections and long-term safety in athletes.
September 22, 2018
Is it safe?
Happy Autumn 2018 (or Spring, if you are one of our readers from below the equator). It’s that time for another edition of the Clinical Journal of Sports Medicine Online Journal Club, with our regular contributor, Jason L Zaremski, MD, CAQSM, FACSM, FAAPMR. The subject of today’s post is one of the original research articles highlighted in our September 2018 thematic issue on pain control in athletes.
Introduction: The fall Journal Club commentary for the Clinical Journal of Sports Medicine (CJSM) will be an analysis of research examining the perceived side effects and long term safety of local anesthetic injections in professional rugby players over a 6 year period. Local anesthetics are a treatment modality used to reduce or eliminate pain in injured professional athletes with the goal of expedited return to play. Pain control and appropriate pharmacological interventions are a current hot topic not only in sports medicine but in all of medicine and society. Consequently, this study by Sebak et al. in the September issue of the CJSM is a very interesting, time appropriate, and novel contribution to the literature of treatment options for pain control. We thank our colleagues in Australia for a wonderful contribution to the CJSM and sports medicine literature.
Hypothesis: The authors hypothesize that local anesthetic injections are reasonably safe. They predict that data from this study will reinforce the results of a previous similar study with similar authors from 1998-2007.
Dr. Jason Zaremski, Jr. Assoc. Editor of CJSM, and author of the CJSM Blog Online Journal Club posts
Methods/Design: This was a retrospective case series evaluating the long term safety of local anesthetic injections before or during games involving professional rugby league players. The participants included players from the Sydney Roosters, a member of Australia’s National Rugby League (NRL), from 2008-2013. Each of these players had been administered a local anesthetic injection for an injury before or during a match to aid return to play. The decision to treat was based upon the site of injury, level of pain, and the ability of the athlete to continue to play. The authors stated that verbal consent was obtained at the time from players by the treating physician, but no waiver was signed or written consent obtained. The study was approved by the Human Research Ethics Committee at the University of Sydney as well as approved by the NRL Research Board.
Data Acquisition: A database was created including all cases of players who had been injected with local anesthetic for an injury immediately before, or during, a rugby league match from 2008-2013. There were 124 cases in 52 athletes who were treated with an anesthetic injection either anatomically guided (n = 265 injections) or with ultrasound-guidance (n = 104 injections) for a total of 369 injections. The average number of injections per case varied from 1.1 to 4.8. The local anesthetic was primarily Bupivacaine. Of note 8 of the 52 players were still playing at the time of survey. The location of the injuries included: Hand, Wrist, Acromioclavicular (A/C), Sternoclavicular (S/C) and Sternum, Rib, Iliac Crest, Ankle, and other.
Instrument: The survey study was single blinded so those involved in the management of the players did not have access to individual responses. Subjects were de-identified and data were collected and examined by independent assessors to provide players greater anonymity. If the players chose to participate, they would complete the online survey. Data collected were transmitted through a secure network to a database in which data merging was performed before data analysis. Results were compared to the previous study from 1998-2007 (Orchard JW, Steet E, Massey A, et al. Long-term safety of using local anesthetic injections in professional rugby league. Am J Sports Med. 2010; 38:2259–2266.)
Outcome Measures: Player self-reported satisfaction. Survey results were compared with the previous cohort who had received local anesthetic injection from 1998 to 2007.
Statistical Measures: As the authors note, descriptive statistics were applied to examine the study population while the questionnaire findings were reported as percentages. A Chi squared test was used to compare the number of injections performed at high-risk areas between the 2 study populations (2008-2013; 1997-2003) and test the level of significance. Survey results of the two populations were assessed using Mann-Whitney U test. An alpha of P< 0.05 was statistically significant. All statistical analyses were performed using IBM SPSS Statistics for Windows, V24 (IBM Corp, Armonk, NY).
Results/Outcomes: There were a total of 124 cases and 369 total injections with an average of 3.0 injections per patient. Follow-up data for 32 out of 52 players (61.5%) and 81 of 124 cases (65%) were collected. A/C joint injuries were injected with the greatest frequency at an average of nearly 5 injections per A/C joint injury. Iliac crest contusions were injected with the least volume for all known injuries at an average of 1.4 per case. The 32 players had been injected with local anesthetic on 249 occasions for 81 total injuries. The average follow-up 5.64 years post injection. When comparing the 1998-2007 cohort versus the 2008-2013 cohort, A/C joint injuries were injected with the greatest frequency in both cohorts. 96% (78 cases) of players found the injections to be helpful at the time.
Fewer injections were performed to higher risk areas (wrist, sternum, and/or ankle joint) in 2008-2013 as compared to 1998 to 2007 (P=0.00002). 99% of players said they would repeat the injection. There were 6 cases in which players reported significant ongoing pain in the area of injection at long-term follow-up. No side effects from local anesthetic use were reported in 45 out of 81 cases (56%). A significant number of players felt that the anesthetic injection delayed recovery from their injury (29 cases, 36%) and in 5 cases (6%) players felt the injury was worsened by playing with the local anesthetic. 53 players (65%) believed that the primary incentive to use a local anesthetic was either their own desire to not miss a game or to not play the game in pain (25 cases, 31%). There were no reports of sensory nerve block by players in this series. Most players reported minimal to no side effects in 75 cases (93%). There were 6 cases (7%) that reported having significant pain that is unresolved. There was no correlation between the number of injections performed and experiencing long-term pain.
Strengths: This is a well done retrospective survey study with data over a long period of time. The survey was single blinded, which may lead to a greater likelihood of truthful responses from the participants. This study, in combination with the previous study, provides long term data over a 15 year period suggesting that local anesthetic injections may be given safely and effectively to professional rugby league players when administered by an experienced physician.
Weaknesses: There were 20 players (38.5%) and 43 cases (35%) who did not participate in this study and whose data would provide greater detail on the results of the study. The study’s retrospective data acquisition comes with recall bias due to the follow-up time. The study did not have a control group as well as the participants’ past injury history and prior treatment modalities to the affected area(s) where a local anesthetic injection was performed was not available. Reviewing the 6 cases where significant pain was unresolved, it would be important to know if those injections were performed with Ultrasound guidance or not. Additionally, this a niche population (professional rugby league athletes) who traditionally participate in competition in some degree of pain. The results then may not be generalizable to a non-traditional or high level athlete in other, non-contact sports. Finally, this sport is played with a significant amount of contact and minimal protective padding. The injury distribution may be different in other non-contact sports such as cricket, baseball, softball, swimming, soccer, and track & field events.
Conclusion: This study confirmed that the authors’ hypothesis that there is minimal long-term safety of local anesthetic injections. The authors have proposed that the wrist, sternum, and ankle joints are higher risk areas in which injections should be avoided or limited, as they may exacerbate the injury or increase risk of re-injury. Finally, the authors suggest that all intra-articular injections to major joints should be avoided or limited because of the potential chondrotoxicity of local anesthetic on hyaline articular cartilage.
Practice Pearl: Given high satisfaction rates from this procedure, in high level athletes local anesthetic in low risk areas (i.e. not the wrist, sternum, ankle joint as well as knee joint based on a prior study) should be a consideration for pain control as opposed to alternative pain-relieving options such as Narcotics or oral Non-Steroidal Anti-inflammatory medications.
Clinical Relevance: Injections may be given safely and effectively to professional rugby league players when administered by an experienced physician. However, there is a small risk of long-term complications.
—Jason L. Zaremski, M.D.
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