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General Review

Use and Outcome of Local Anesthetic Painkilling Injections in Athletes: A Systematic Review

Gultekin, Sinem BBiomed Sci*; Chaker Jomaa, Mohammad MBBCh; Jenkin, Rebekah PhD; Orchard, John W. MBBS, BA, PhD, MD, FACSP, FACSM, FASMF, FSEM (UK)§

Author Information
Clinical Journal of Sport Medicine: January 2021 - Volume 31 - Issue 1 - p 78-85
doi: 10.1097/JSM.0000000000000716
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Abstract

INTRODUCTION

Local anesthetic use to mask pain of injury is common in professional football codes, despite a dearth of published information regarding its safety. A 2016 survey of National Football League (NFL) physicians found that 100% of responding physicians used local anesthetic injections on players to facilitate play.1 Publications involving athletes in Australian football,2 rugby league,3,4 and soccer5,6 have all documented common use of local anesthetic in elite sport.

Medicolegal cases dating as far back as the 1960s (Krueger vs San Francisco 49ers)7 have argued that the practice of using a local anesthetic injections to remove pain from an injury may be dangerous, with a risk of causing long-term damage to the player. Recently, an NFL painkiller lawsuit (Dent vs NFL)8 identified the use of local anesthetic painkilling injections as an alleged item of negligence. To date, all allegations of negligence have been based on expert testimony rather than robust systematic review of biomedical evidence.7,8

For an athlete in pain, it can be presumed that the safest option is to refrain from play until pain resolves. However, decision-making regarding return to play is a complex process and involves multiple factors. The pressure is on the athlete to play and perform; contracts of professional athletes are regularly reassessed based on performance,9 and injured athletes who do not compete in sufficient games risk losing their contract and hence professional status. Missing game time is often not an option that athletes are willing to consider, especially when they deem participation to involve an “acceptable level of risk,”9 such as in instances of pain where musculoskeletal stability and integrity is otherwise maintained. From the physicians' perspective, return to sport should be viewed as a continuum, paralleled with recovery and rehabilitation rather than being a decision taken in isolation at the end of recovery and rehabilitation.10

Therefore, where the focus is to ensure athletes continue to play, the use of local anesthetic painkilling injections should be compared with the alternative options, such as enduring the pain associated with injury or using an alternative analgesic [such as a nonsteroidal anti-inflammatory drug (NSAID), cortisone injection or opiate analgesics]. It is important to recognize that alternative analgesics are not free from side effects or risks.11,12 For some injuries, local anesthetic is superior in efficacy in that it may give 100% block of pain versus the partial relief afforded by other analgesics.

Given the documented widespread use of anesthetic injections, and the importance of establishing how safe the practice of injecting injuries with local anesthetic is, a systematic review of this topic is required. As of the commencement of this review, we are unaware of any previous publications on the topic other than primary articles or narrative reviews. The primary objective of this study was to provide a systematic review of available literature on the practice and follow-up of local anesthetic injections in elite athletes to facilitate pain-free competition. Secondary objectives include compiling evidence on the anatomical sites targeted for injection and any evidence regarding their long-term effects.

METHODS

This systematic review was undertaken with use of the PRISMA methodology. Two authors (S.G. and M.C.J.) independently conducted a systematic search of MEDLINE, Embase, CINAHL, AMED, Cochrane Database of Systematic Reviews, SportDiscus, EBSCO Host, and Google Scholar on April 30, 2018.

The MEDLINE search was conducted using preagreed MeSH terms and Boolean phrases (Athletes/or Athletic Injuries/or Sports/AND Anesthetics, Local/or injections, intra-articular/or injections, intramuscular/) following a refined process, which was designed to comprehensively cover all articles within our field of study to warrant inclusion within our review. The search was limited to only articles published in the English language between 1946 and the third week of April, 2018.

To be eligible for inclusion in this review, a study needed to document game-day local anesthetic use on an athlete for the purposes of competition and to facilitate return to play. For studies to satisfy our inclusion criteria, injections therein must be described as containing local anesthetic injections only and having been given before or during competition. The role of the injection must have been to assist with participation under an “anesthetic block.” For the purposes of inclusion in our study, a professional athlete was originally defined as aged older than 18 years and participating in sport at an elite (national or international) level. However, most of the studies did not specify player age, and as a consequence, a minimum age was not included as criteria for inclusion in the final review.

Injections given outside of competition (eg, after game) or used in conjunction with a therapeutic agent, such as corticosteroid injection or NSAID, were excluded from the study. In these instances, it was assumed that the purpose of the local anesthetic part of the injection was used to either (1) minimize pain associated with an alternative therapeutic agent or (2) as part of the diagnostic process in ensuring the accuracy of the injection site.

Our initial search strategy identified a paucity of publications that satisfied our inclusion and exclusion criteria. We therefore undertook additional searches using citation tracking and “forward hand search” to identify additional studies. The search strategy and results are detailed in Figure 1.

Figure 1.
Figure 1.:
Prisma diagram.

To avoid possible bias, all searches were performed by those authors (S.G. and M.C.J.) who had no previous research publications in this field. Similarly, the judgments on length of follow-up were made by coauthors not involved in authorship of included studies.

Study authors were contacted in instances where further explanation of data sets was needed, for example, when the circumstances surrounding injections were unclear.

Once a study had been identified as meeting the inclusion criteria, the study quality and results were assessed in accordance with the STROBE statement,13 with relevant study characteristics summarized, including for cohort/case series studies. The duration of athlete follow-up was considered of significant importance, as short-term/zero/unrecorded follow-up would miss any medium or long-term complications associated with local anesthetic use.

Results were then assessed to examine characteristics associated with short- and long-term safety, in particular records of complications from injections and, where undertaken, long-term follow-up. Reported complications were extracted from all identified articles. This included single case studies included or referred to in articles.

Long-term follow-up was defined as being of or greater than a 5-year duration; with short-term follow-up defined as only encompassing review of the athlete's condition in the season/year of procedure/injury. Follow-up periods between 1 and 5 years of duration were therefore considered medium‐ term.

RESULTS

The search strategy and identified relevant articles are detailed in Figure 1. Of the excluded articles, the most common reason was the use of corticosteroid injections with local anesthetic. For example, one study that documented 69 athletes, 88 injuries, and 128 injections of “corticosteroid and local anesthetic”14 was excluded as every injection contained corticosteroid as the primary agent. Another article reported 37 local anesthetic and corticosteroid injections within its treatment of 31 athletes; however, on further clarification, only 2 of the injections satisfied our inclusion criteria being a game day injection of local anesthetic, and it was included using only the findings relating to these 2 cases.15

In total, 10 primary studies, which satisfied our inclusion and exclusion criteria, were identified (Table 1). A total of 1970 local anesthetic injections reported within these articles were included in our study. The total number of local anesthetic injections in Table 1 refers to injections that were performed and met the inclusion criteria. The number of injections in 2 articles (by Orchard et al3 and Sebak et al4) recorded in Table 1 refers to the total number of injections performed by the team physician. Both of these studies used questionnaires to follow up on injections, and because of this, there was a decreased number of responses regarding injections surveyed than the actual number of injections originally performed by the team physician.

TABLE 1. - Case Audit
First Author Sport # of Injections # of Injuries (Cases) # of Athletes
Drakos15 American football 2* 2* 2*
James19 Australian football 11 8 8
McAdams20 American football 2 1 1
Orchard BJSM2 Australian football 236 107 37
Orchard AJSM3 Rugby league 1026 307 100
Sebak4 Rugby league 369 124 32
Tscholl, 200816 Soccer 148 ? ?
Tscholl, 200917 Soccer 61 ? ?
Tscholl, 201218 Soccer 53 ? ?
Vaso6 Soccer 62 ? ?
Total numbers 1970 >549 >180
*Only 2 injections from this article were confirmed as pregame local anesthetic injections, despite the study reporting many more “injections,” most of which were mid-week corticosteroid injections.
These values refer to the number of injections and cases in total and differ from the number of injections and cases that was followed up in these studies.
Individual number of players injected and number of injury cases cannot be calculated as number of duplicates unknown.

Two of the rugby league studies had substantial case overlap, with most of the rugby league cases from Orchard2 also being reported with much longer follow-up in Orchard et al.3 The Australian football cases (only) were extracted from Orchard's article in Table 1, so as to not count the rugby league cases from this study twice, when the data were pooled with the later study by Orchard et al.

The study by Tscholl et al5 synthesized the data from the study by Tscholl et al,16 Tscholl et al,17 Tscholl,18 and Vaso.6 The synthesis study was excluded as a duplicate, as it did not split between corticosteroid and local anesthetic injections, whereas the 4 primary studies (which were included) listed specifically the number of local anesthetic injections, although not the number of players receiving the injections.

Table 2 details an overview of study quality, including length and type of follow-up. Only 2 studies included follow-up of athletes subsequent to the clinical relationship between physician and patient having ended.3,4 These were both in the sport of rugby league and involved a player questionnaire at an average of 5 years after injection use. Two further studies, Drakos et al15 and Orchard,2 reported “clinical” follow-up, suggesting that complications were documented, as they became apparent during the ongoing physician–patient relationship. One study19 stated that follow-up occurred; however, the results only pertained to immediate postinjection complications; this seemed to be the same day during a game, and no complications were reported to have occurred. Five of the studies6,16–18,20 reported the use of local anesthetic injections without any clinical or long-term follow-up. Bias, funding and ethics of each article were also noted, with the most common bias being that the authors of 5 articles were the treating physicians. Four of the articles that reported on injections in soccer were funded by a large soccer federation.5,16–18

TABLE 2. - Study Quality Parameters Assessed
First Author Baseline Characteristics of LA Cohort Described Follow-up Type Follow-up Percentage Outcome Variables Bias, Funding, and Ethics
Drakos15 Sport/team only recorded characteristic Tracked for 3 seasons (number of missed days, practices, and games recorded), clinical records 100% (but no player follow-up; clinical notes only) Clinical records only Potential bias (team doctors reporting results of own treatment). No external funding. Institution approved.
James19 Sport/team only recorded characteristic Only follow-up straight after injection + during game 100% (but no player follow-up; clinical notes only) Clinical records only Potential bias (team doctors reporting results of own treatment).
McAdams20 Sport/team only recorded characteristic Nil No follow-up No variables assessed Potential bias (team doctors reporting results of own treatment and experience).
Orchard BJSM2 Sport/team only recorded characteristic Routine (weeks-years) Clinical records 100% (but no player follow-up; clinical notes only) Clinical records only Potential bias (team doctor reporting results of own treatment). No external funding. No ethical oversight.
Orchard AJSM3 Sport/team only recorded characteristic Delayed follow-up (avg. 5 yrs of follow-up, minimum of 1-yr follow-up) 81% follow-up through retrospective survey Survey questionnaire (safety and efficacy) plus game performance statistics (objective measure of efficacy) Potential bias (team doctors reporting results of own treatment). No external funding. Institution approved.
Sebak4 Sport/team only recorded characteristic Delayed follow-up (5.64 years after injection) 62% of players and 65% of cases follow-up through retrospective survey Survey questionnaire (subjective measures of safety and efficacy) Independent authors managing follow-up. No external funding. Ethics committee approved.
Tscholl16 Age groups and sex reported Nil No follow-up No variables assessed No outcomes assessed for bias consideration. Ethics committee approved. Externally funded (FIFA).
Tscholl17 Age groups and sex reported Nil No follow-up No variables assessed No outcomes assessed for bias consideration. Ethics committee approved. Externally funded (FIFA).
Tscholl18 Age groups and sex reported Nil No follow-up No variables assessed No outcomes assessed for bias consideration. Externally funded (FIFA).
Vaso6 Age groups and sex reported Nil No follow-up No variables assessed No outcomes assessed for bias consideration. Institution approved and funded (FIFA).

The most commonly reported injection sites are detailed in Table 3: the acromioclavicular (AC) joint (n = 440); hands (including fingers) (n = 362); the sternoclavicular (SC) joint and sternum (n = 203); ribs (n = 152); and the iliac crest (n = 110). Some articles reported the use of injections in areas that did not fit into the 7 broad categories listed. These injections were small in number and therefore were included in one combined “other” category. In total, 217 injections were performed in varying locations, including but not limited to toes, prepatellar bursa, and Achilles tendon. Three hundred twenty-four injections were unable to be categorized, as location was not specified in the primary articles.

TABLE 3. - Sites of Injections
Injury Type Total Injections
AC joint injuries 440
Ankle injuries 76
Hand 362
Iliac crest contusions 110
Rib injuries 152
SC joint and sternum injuries 203
Wrist injuries 86
All other specified injuries (incl. toe and prepatellar bursitis) 217
Undocumented/unspecified 324
Total 1970

The short-term complications identified from the use of local anesthetic injections occurred in a wide variety of injected areas as shown in Table 4. Most were reported to have resolved in the longer term, although this statement is limited by the lack of long-term follow-up in all cases.

TABLE 4. - Complications* (Compiled From All Articles)
Body Part Type of Complication
Achilles tendon Partial rupture of Achilles tendon at anterior portion insertion, which required immediate surgery, recovered next season.2
Ankle Medial plantar nerve sensory block, player able to return to play with numb sole of foot2
Local injection of os trigonum for one game, elective surgery to remove2
Ruptured plantar fascia origin from chronic plantar fasciitis, missed 2 wk but fully recovered2
Superficial peroneal nerve block for lateral ankle sprain causing numb dorsum of foot, asymptomatic and able to play2
Groin Partial rupture of adductor longus tendon, which required delayed surgery, recovered2
Hand Ruptured flexor tendon of the fourth finger, surgery on the injury after a single game due to loss of function of hand during play3
Osteoarthritis of first metacarpophalangeal joint complicated from initial fracture but suspected to be worsened by 6 wk of blocks, asymptomatic2
Iliac crest Lateral femoral cutaneous nerve block2
Iliac crest hematoma, significant bleeding and bruising after the game, as low as the scrotum3
Iliac crest hematoma, chronic lumps in the region of injection that were nonpainful3
Prepatellar bursitis (knee) Mild prepatellar bursa infection, fully recovered2
Rib Failed block for rib fractures with player unable to play, successful block the following week2
Shoulder including AC joint Distal clavicle osteolysis (2 cases), full recovery after postseason surgery2
Supraspinatus tendon tear, progressed to a complete rupture, surgical repair with 9 months of recovery3
Sternoclavicular joint Sprain of joint was worsened by further contact mechanism, 4 games missed2
Wrist Scapholunate ligament tear, required end of season surgery then recovered2
Slight malunion after first metacarpal fracture and loss of full thumb span, anticipated and expected by player2
Trapezium contusion, complete fracture resulting in internal fixation surgery with subsequent recovery3
Base of thumb ligament injury with chronic instability of the joint and pain, did not resolve years later3
*Each is a single complication in a single athlete as described in the literature. Some injections may have had complications not described.

Information from 2 studies3,4 that have used a consistent questionnaire methodology and included long-term follow-up and patient satisfaction was analyzed. The number of combined cases from which the data are calculated is presented in these tables (5 and 6) along with a calculated percentage outcome of each survey response. Table 5 summarizes data on reported player pain after injection, whereas Table 6 summarizes player satisfaction with the injection. Overall 68% of athletes reported that they experience no long-term pain in the body part injected, with only 1% experiencing pain every day that affects their enjoyment of life. One percent (1%) of athletes would not repeat the injection, whereas 61% of athletes would be completely happy to repeat their injection.

TABLE 5. - Long-Term Pain Associated With Local Anesthetic Use3,4
Injury Type (No. of Cases) None at All in That Body Part n (%) An Occasional Niggle but Nothing Too Severe n (%) Some Bouts of Significant Pain and Not Back to Normal n (%) Pain Every Day That Affects My Enjoyment of Life n (%)
Hand injuries, n = 82 58 (72%) 19 (23%) 4 (5%) 1 (1%)
Wrist injuries, n = 15 7 (47%) 5 (33%) 2 (13%) 2 (7%)
AC joint injuries, n = 54 36 (67%) 16 (30%) 2 (3%) 0 (0%)
Rib injuries, n = 37 33 (88%) 4 (11%) 0 (1%) 0 (0%)
SC joint and sternum injuries, n = 56 28 (51%) 20 (36%) 7 (13%) 0 (0%)
Iliac crest contusions, n = 29 26 (90%) 2 (7%) 0 (0%) 0 (3%)
Ankle injuries, n = 18 11 (61%) 5 (28%) 2 (11%) 0 (0%)
All other injuries, n = 39 26 (68%) 11 (27%) 1 (3%) 1 (2%)
Total, n = 330 226 (68%) 81 (25%) 18 (6%) 4 (1%)

TABLE 6. - Overall Satisfaction on the Use of Local Anesthetic3,4
Injury Type (No. of Cases) Completely Happy to Repeat n (%) Happy on Balance n (%) Would Repeat but Would Not Recommend to Others n (%) Would Not Do It Again n (%)
Hand injuries, n = 82 57 (70%) 19 (23%) 6 (7%) 0 (0%)
Wrist injuries, n = 15 10 (66%) 2 (14%) 2 (14%) 1 (6%)
AC joint injuries, n = 54 29 (54%) 16 (29%) 9 (17%) 0 (0%)
Rib injuries, n = 37 22 (59%) 12 (33%) 3 (8%) 0 (0%)
SC joint and sternum injuries, n = 56 28 (51%) 15 (26%) 13 (23%) 0 (0%)
Iliac crest contusions, n = 29 19 (64%) 9 (32%) 1 (4%) 0 (0%)
Ankle injuries, n = 18 12 (65%) 2 (12%) 1 (5%) 3 (18%)
All other injuries, n = 39 24 (63%) 14 (35%) 0 (0%) 1 (2%)
Total, n = 330 201 (61%) 89 (27%) 35 (11%) 5 (1%)

DISCUSSION

The most remarkable finding from this systematic review is the low number of publications that have documented local anesthetic use in the peer-reviewed literature, and the even rarer occurrence of long-term follow-up and evaluation of functional and satisfaction outcomes. If the practice of local anesthetic injection is as common as suggested (eg, the 100% of surveyed-NFL physicians using local anesthetic injections on occasion1), then a far greater publication and evidence base would be expected. The broader specialty of Sport and Exercise Medicine now encompasses a higher-quality scientific basis on which to base management (eg, multiple randomized control trials), but practices generally limited to professional/elite sport can evidently be quite common notwithstanding the absence of an adequate evidence base of efficacy and safety. Every one of the 10 studies that was eligible for inclusion in the review represented one of the codes of football (rugby league, Australian football, American football, or soccer). Although it is quite likely that local anesthetic injections are used in other sports to allow players to continue playing,7 we were only able to identify published case series in the football codes. In addition, we can report that the study quality in general was very low (Table 2). Half of the studies did not report any follow-up; only 2 studies included long-term follow-up, and even those 2 only included follow-up with subjective measures (survey questionnaire). Most of the studies were potentially biased in terms of being undertaken by the primary clinicians who performed the injections. Where follow-up was obtained, the information collected was more focused on safety (complications and long-term outcomes) than efficacy (Were the injections successful in the short-term, particularly in comparison with another treatment option?). There is a general assumption, which seems reasonable, that local anesthetic is reliably able to relieve pain in the short term (ie, efficacy is assumed for certain injuries) with the research question needed being whether this results in short- or long-term damage to the body part being injected.

On the basis of the evidence reviewed in this article, it can be concluded that local anesthetic painkilling injection use in the football codes is neither completely safe nor unsafe. The studies we reviewed have reported some long-term significant complications (ie, associated with functional impairment persistent at a period of over 5 years)3,4 and evidence that for certain injuries their use may be complication-free. There are moderately large cohorts for certain injuries (eg, AC and SC joint) with at least medium-term follow-up (1–5 years) where the procedures are generally reported to be complication-free. From the evidence reviewed, it seems that AC joint injuries, finger injuries, and iliac crest hematomas are more likely to be reported to have remained complication-free than some other sites. By contrast, injection of knee joints, thumb and wrist injuries, and ankle joints seems to be less safe, as these injuries featured prominently in the documented list of complications across all studies. These sites also are associated with reported longer-term complications. Rib and sternum injuries are a middle ground with respect to safety, in that the complication of pneumothorax, which is a serious short-term complication, has been described,21 but long-term complications have not.

These findings could perhaps be explained by the differences in anatomical architecture and design of musculoskeletal tissues and joints. In instances where structures injected have suffered minimal change to biomechanical loading capacity (eg, low-grade AC/SC joint sprain or iliac crest hematoma) or are protected from further loading (eg, strapped fingers), there is perhaps a lower risk of postinjection compromise. Alternatively, injecting primary load-bearing joints (eg, knee, wrist, and ankle) seems to increase the risk of more reported long-term symptoms. It is unclear whether this is related to a different profile of structural injury, uninhibited overloading of (and therefore further damage to) the injury site, or simply whether these joints are more susceptible to chronic pain and impairment postathletic career.22 None of the studies to date has undertaken objective assessment of long-term complications, which would assist in answering this question.

This article represents a consolidated attempt to systematically review the evidence relating to the use of local anesthetic injections to treat players in football codes. A technical limitation of this study is that there is crossover between the coauthors of this review and the authors of some of the previous studies. This is a minor limitation in that grading of follow-up was straightforward with minimal subjectivity, so it is highly unlikely that independent authors would reach a different conclusion.

The more substantial limitation is that the cases described in this review may not be representative of the injection cases being performed in elite sport as a whole. Although it is possible that the cases overrepresent the use of local anesthetic injections, the available evidence is that it is more likely that the reported cases are an underestimate of the use of these injections. Furthermore, given that most of the articles included in this study were led by clinicians active in the treatment of players, the cases included may also be unrepresentative, arising from the activities of a particularly cautious or curious subgroup of physicians. It is unknown whether physicians who never had any interest in follow-up or research publication would be injecting a similar profile of injuries and with similar frequency. As far as we are aware, there is no “universal compulsory requirement” for injection registries administered by central sporting bodies. If such registries were compulsory, with regular review and audit, then the capture rate of injection documentation should theoretically be quite high, and a central competition body in the future could document a far more complete profile.

It is also important to note that this study specifically excluded cases of local anesthetic being used as part of a combination with other agents (eg, corticosteroid). In the reviewed literature, “local anesthetic injections” can refer to both pregame and in-clinic injections (combined with corticosteroid or other preparation).15 Studies combining these 2 different uses were excluded from this study. Furthermore, studies which report injections of, say, corticosteroid, do not necessarily mention if local anesthetic is used (on the presumption that the “active” agent is not the anesthetic). It would be preferable if all studies that discuss “injections in athletes” clearly list the total use of all medications (local anesthetic and other) as well as the location and consulting environment of all injections.

In a broader context, the use of painkillers in elite sport by players seeking to return to the game is very common. Although local anesthetic use is among the options favored, in one comprehensive study, it was only the fifth most commonly used pain reliever.6 The most common alternative option that elite athletes consider when deciding whether to proceed with local anesthetic injections is an oral analgesic. However, given that these drugs have well-documented side effects and/or risks,11 the use of local anesthetic injections on the available evidence is an alternative which may be effective and acceptable to players.

CONCLUSIONS

There are limited peer-reviewed studies regarding the safety of using local anesthetic injections to allow for ongoing elite athlete game participation. Of the articles that have been published, there is some evidence of long-term safety, particularly regarding AC joint and some finger injuries in footballers. Further studies are required, as is better clinical documentation of the use of these injections, their effectiveness, and any complications. Overall, the results of this review suggest that use of local anesthetic injections should be performed with caution.

ACKNOWLEDGMENTS

The authors would like to thank Ms Sophie Sebak for her early contributions to the paper.

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Keywords:

local anesthetic; injection; athlete; sport; painkilling

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