Keywords

Abstract

Groin injuries are one of the most common types of injury in the Australian Football League (AFL). Australian football is a code that was developed within Australia as a means for cricket players to stay fit during winter. The playing surface varies in size (cricket ovals are often used) but is larger than for all other football codes. There are 18 players per side on the field, with 4 players allowed for unlimited interchanges. The game is played over four quarters of 20 min (plus approximately 10 min of added time for stoppages), with the ball actually "in play" for a total of 60 min [1]. The 16 teams play once a week over a 22-week regular season. The primary method of ball progression is punt kicking. The physiological requirements are similar to soccer (of the major football codes), although the players have often been likened to 1500-m runners, with a generally tall and thin athletic build that requires a mix of aerobic and anaerobic running, kicking, and jumping efforts. The most similar code is another indigenous sport, Gaelic football. The two games are similar enough for Australia and Ireland to be able to play regular Test matches under combined rules. One former Gaelic footballer was able to transfer to the Australian Football League to become one of its premier players. One former professional AFL player is now a successful specialist punter in the National Football League (U.S.).

The objective of this study was to review the published rates of groin injury within the AFL and to summarize the current approaches to management among AFL team physicians.

The AFL Medical Officers Association has maintained a database of injuries during the regular season since 1992 [2]. Early results from this survey have been published in the peer-reviewed medical literature [2, 3], as were the results of a previous survey of Victorian Football League (VFL) injuries from 1984-86 [4]. The most recent results from this survey have been published in an annual Injury Report by the AFL, which is released to the Australian media in April-May each year [5-7]. The definition of an injury for the most recent years of the survey has been "any physical condition that causes a player to miss a match during the regular season." This definition has ensured consistency in reporting from year to year and between teams. It is anticipated that the 1999 AFL Injury Report will be released in March-April 2000 by the AFL, with a summary available on the AFL website <www.afl.com.au>.

The AFL Medical Officers Association meets regularly to discuss issues that are of concern to team physicians throughout the competition. Many conference presentations regarding groin injuries in the AFL have been made at the annual Australian Conference of Science and Medicine in Sport (proceedings available from Sports Medicine Australia, Canberra). A small number of these have also been published as full papers in the peer-reviewed literature. A symposium on groin injuries was conducted at the Football Australasia conference, with published abstracts [8].

Groin injuries are the second most common injury category in the AFL, with hamstring strains being the most common (Table 1). Groin injuries also represent the third most common source of missed playing time after hamstring strains and ACL tears (Table 2) [7]. Severity of injury (based on average number of weeks missed per injury) can be calculated by dividing the prevalence (Table 2) by the incidence (Table 1). Based on this measurement, the average groin injury results in 3 weeks of missed playing time (13.9 ÷ 4.6). A team-season represents 880 player weeks (average playing roster of 40 with a regular season of 20 weeks). Therefore, an AFL club can expect an average of four groin injuries to result in 12 missed player games per season.

Table 1 Incidence of Most Common Injuries in the AFL (Injuries/1,000 Player Weeks)

Injury category	1992	1993	1994	1995	1996	1997	1998	Average
All injuries	53.2	47.1	45.2	47.2	48.0	50.9	46.5	48.2
Hamstring strain injuries	11.0	8.6	9.1	9.1	7.5	8.8	8.1	8.8
Groin and hip injuries	3.9	3.6	4.8	4.4	5.0	5.8	4.3	4.6
Ankle joint injuries	3.5	3.3	2.1	2.5	3.2	3.2	3.9	3.1

Note. Incidence in a unit of "injuries/team season" can be calculated by multiplying by 880 and dividing by 1,000.

Table 2 Matches Missed Due to Injury for Most Prevalent Injuries in the AFL (Weeks Missed/1,000 Player Weeks)

Injury category	1992	1993	1994	1995	1996	1997	1998	Average
All injuries	167.8	141.6	132.6	150.5	166.2	177.7	160.9	157.1
Hamstring strain injuries	23.7	21.4	19.2	22.3	19.4	23.6	23.3	21.8
Anterior cruciate ligament injuries	17.8	6.7	12.5	16.2	21.0	21.5	18.0	16.5
Groin and him injuries	13.2	10.8	11.9	11.6	13.1	20.3	15.4	13.9

The incidence and prevalence of groin injuries have increased slightly from 1992-1998. An increase in speed of the game has been postulated as a possible mechanism for an increase in injuries [1].

For the purpose of the AFL Injury Report, the categories that are summarized represent the most specific diagnoses for which there is universal agreement among the medical staff at each team. There are no uniformly accepted diagnostic criteria for groin injuries; hence, no distinction can be made between, for example, adductor tendonitis, osteitis pubis, "sports" hernias, and obturator nerve entrapment. The principal diagnosis is often dependent upon the individual belief of the treating team physician that is in turn influenced by various regional and clinic bias. A recent review of groin strains in the National Hockey League divided strains into groin and abdominal, but conceded that it was difficult to ensure that all teams used similar criteria for distinguishing between the two injuries [9].

All of these more specific diagnoses are recognized internationally, although obturator nerve entrapment has only been described by Australians to date [10]. (In a recent study published in The Lancet [11], one patient with chronic groin pain was unavailable for follow-up due to "immigration to Australia." It was not stated whether this was specifically to obtain an obturator nerve release!) Fascial release may become a common aspect of all groin surgery.

Gradual-onset groin injuries resulting from overuse are generally managed conservatively during the AFL season by all teams. An acute onset injury may require extended rest initially, but the more common manifestation of groin strain is increasing post-game soreness over a period of weeks. At any given time, this level of symptom may be prevalent in 10-25% of the squad [12]. The first-line management is to reduce the training load of the player by decreasing the intensity and frequency of his training drills during the week. The drills most commonly changed involve a combination of sprinting and kicking, as these are considered to place the most stress on the groin structures.

Analgesics and NSAIDs are used widely for in season management of groin injuries. Corticosteroid injections are favored by some doctors but avoided by others. Occasionally some team doctors will use local anaesthetic injections of Bupivicaine to attempt pain relief for competition. This practice of local anaesthetic injection has been reputed to be associated with some severe cases of chronic pain, so it is best used with caution, if at all. There have been some infamous cases of players being unable to kick during matches due to inadvertent femoral nerve anaesthesia as a complication of pre-match injection [8].

The recommended management at the end of the season for the case of a player with chronic groin pain is usually dependent on the diagnosis made by the team physician [8]. Management is either non-surgical or surgical, with both of these strategies using rest to varying degrees. The most favored form of surgery is the repair of the posterior inguinal canal wall, with the open Bassini-type hernia repair being the most common single procedure [13], and a more medial posterior wall procedure, a conjoint tendon repair, being another. Other operations performed either alone or in combination with a posterior inguinal wall repair include adductor tenotomy, obturator nerve release, and pubic symphysis ostectomy. The strategy used by team physicians for post-season management is usually either: (1) preference for a common diagnosis as the primary cause of chronic groin pain and hence use of one of these procedures routinely on all players with chronic groin pain at the end of the season, with the viewpoint that it has provided their team with the best results over the years; or (2) preference for multiple diagnoses as the cause of chronic groin pain, with an attempt to match treatment with the specific diagnosis or diagnoses made. It is said that where many different surgical procedures are recommended by different experts that it is because either "they all work or none of them work," and it is debatable which is the case for groin surgery. It is also difficult in the surgical treatment of sports-related chronic groin pain to assess the role of enforced rest. There is an emerging school in support of conservative management, with the premise that groin injuries are generally a bony stress overload [14]. Extended rest as a non-invasive approach to the treatment of chronic groin pain is a difficult viewpoint to hold in an AFL club, where there is pressure from management (and often from the player himself) to perform off-season surgery, as surgery has been accepted as routine treatment for this condition for the last 15 years.

As previously mentioned, groin injuries are the second most frequent injury in the AFL, with an injury incidence of 4.6 injuries per 1,000 player weeks. This high incidence results from the costly demands of the game, including punt kicking, sprinting, and change of direction.

The AFL is an excellent environment in which to compare the relevant merits of conservative and surgical treatments for chronic groin injuries. This would require all teams to provide details of operative management for all players in the off-season, which is not currently being done. From a scientific viewpoint, the ideal method for comparison would be a randomized control trial, which is not practical in professional sport. If a randomized trial was designed in a non-professional setting (also a difficult task), an immediate challenge would be to standardize the level of activity to which subjects attempt to return. Attempted level of activity (load) on return from injury is probably the most important predictor of the likelihood of success no matter the form of management. A non-randomized comparison in a professional competition may be the next best study to compare different forms of surgery. Given that the AFL has a rate of groin injury comparable to any professional sport league in the world, perhaps it will become known as the Australian Football Laboratory for unraveling the mysteries of the groin.

Acknowledgments

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