HIP AND GROIN PROBLEMS IN THE PREVIOUS SEASON ARE ASSOCIATED WITH IMPAIRED FUNCTION IN THE BEGINNING OF THE NEW SEASON AMONG PROFESSIONAL FEMALE ICE HOCKEY PLAYERS - A CROSS SECTIONAL STUDY

Abstract

Background:

Hip and groin problems are common in ice hockey but studies on professional female players are sparse. The available literature describes hip and groin problems by reporting incidence of time-loss injuries and may thereby underestimate the scope of these problems, which are often due to overuse and may not lead to absence from ice hockey participation.

Purpose:

The purpose of this study was to describe the seasonal prevalence and severity of hip and groin problems in professional female ice hockey players. A further aim was to examine the relation between previous problems and self-reported function in the beginning of the new season.

Study design:

Cross-sectional study.

Methods:

Female ice hockey players from the highest league in Sweden [n=69 (19 goalkeepers, 18 defenders, 30 forwards)], responded to an online survey, retrospectively assessing the prevalence of hip and groin problems (time loss and non-time loss) and their duration during the previous season. Furthermore, players reported current self-reported function on the Copenhagen Hip and Groin Outcome Score (HAGOS).

Results:

Two thirds of the players experienced hip and groin problems during the previous season [62.3% (N=43)]. A quarter of the players experienced a hip and groin problem leading to time loss [26.1% (N=18)]. The majority of problems were of short (1-2 weeks) or medium (3-5 weeks) duration [29% (N=20) of players, respectively], while longstanding problems ( ≥ 6 weeks) were rare [4,4% (N=3)]. Players that retrospectively reported hip and groin problems during the previous season reported statistically significant impairments on all HAGOS subscales in the beginning of the new season (p ≤ 0.011).

Conclusion:

Hip and groin problems are prevalent in professional female ice hockey players, experienced by 62% during the previous season with resulting time-loss in 26.1%. Reported problems were rarely of longstanding nature, but players who reported problems in the previous season had significantly impaired hip and groin function in the beginning of the new season. Even though results of this study are based on retrospective player reports this may be a first step toward a greater understanding of the true burden of hip and groin players in professional female ice hockey players.

Level of evidence:

3b

INTRODUCTION

The number of girls and women playing ice hockey in Canada and the United States is increasing exponentially^1,2 making it one of the most rapidly growing female sports in North-America.³ However, continuing to play the game at the collegiate level does not come without risk. Ice hockey is among the top three sports with the highest overall game injury risk in women's collegiate sports⁴ and tops the list of sports with highest rates of groin injuries.⁵ The burden of hip and groin problems on professional players, however, is currently unknown.

Hip and groin problems have one thing in common. The main symptom is groin pain, regardless of whether the underlying cause is the hip joint or surrounding soft tissues.^6,7 Muscle strains are the most common injuries to the hip and groin^1,8 in ice hockey and are characterized by high recurrence rates.^8,9 Considering that three quarters of all hip and groin problems in ice hockey are due to overuse,⁸ it can be argued that many of these recurrent injuries actually may be exacerbations of the same underlying problem. Players suffering from such an overuse injury do not necessarily report these problems and can often continue to train and play despite having pain.¹⁰ However, the current literature generally describes hip and groin injuries in ice hockey by reporting incidence rates of injuries that lead to time loss (defined as an injury resulting in inability to participate in ice hockey training or competition)^8,9,11-13 or requiring medical attention (defined as an injury that is treated by a medical official, which in turn reports the injury).^1,8,9,11,14 Hence, a large proportion of hip and groin problems in female ice hockey therefore likely never surfaces in current injury statistics. Consequently, the true burden of hip and groin problems on female ice hockey players is arguably not being captured appropriately by present reporting methods.

The choice of injury definition and reporting method in sports epidemiology should reflect the nature of the injuries aimed to be detected, and the setting in which they are to be reported.¹⁵ If a problem does not lead to absence from sports, using a time loss definition will not capture the full scope of these problems. The medical attention definition of injury depends on the availability of medical professionals that provide treatment and report injuries. In female ice hockey in Sweden, the access to medical care provided by clubs is limited even for professional players. For overuse injuries, such as hip and groin problems, reporting of prevalence, based on player self-report, may provide a more accurate picture of the scope of those problems than incidence rates.¹⁶ In soccer, this strategy has been implemented by a recent study, asking players to report existing hip and groin problems on a weekly basis. The results showed that half of all players experience hip and groin pain over the course of a season, and that traditional reporting methods would have captured just a third of these problems.¹⁷ Furthermore, another recent study indicates that hip and groin problems are not self-limiting and that longer duration of symptoms may have more severe and long-lasting effects on athletes’ function.¹⁸ A similar pattern was recently observed in a study in professional male ice hockey, in which half of all participating players had experienced hip and groin problems in the previous season. Longer duration of these problems was associated with worse self-reported function in the beginning of the new season.¹⁹ Given the rapid increase in popularity of female ice hockey, it is surprising how little attention the sport receives in the sports medicine literature.³ To date, the prevalence of hip and groin problems and their relation to hip and groin function in female ice hockey has not been investigated. Furthermore, existing studies on hip and groin problems in female ice hockey solely investigate youth, collegiate or recreational athletes,^1,8,9,11-14 while there is a complete lack of studies on the issue in professional female ice hockey players.

The purpose of this study was to describe the seasonal prevalence and severity of hip and groin problems in professional female ice hockey players. A further aim was to examine the relation between previous problems and self-reported function in the beginning of the new season.

METHOD

Study design

This cross-sectional survey study describes the magnitude and severity of hip and groin problems in professional female ice hockey players. In the beginning of the 2017/2018 season, all players of the highest league in Sweden [Swedish Women's Hockey League (SWHL)] were invited to participate in an online survey. The online survey assessed prevalence and duration of experienced hip and groin problems in the previous season as well as current self-reported hip and groin function. This study was approved by the Ethics committee at Lund University (Dnr 2017/483) and reporting of results is guided by The Strengthening of Reporting of Observational Studies in Epidemiology guidelines.²⁰

Participants and recruitment

All active players in the SWHL were eligible to participate in the study. An invitation for participation as well as the link to the online survey was provided to the SWHL clubs’ medical teams for distribution to their players. Data collection for goalkeepers was performed within the frame of a separate, prospective study using the same survey.

Questionnaire survey

The web-based survey collected data regarding player demographics such as age, height, weight, playing position and years of playing professional ice hockey. In order to determine seasonal prevalence of hip and groin problems leading to time loss, we asked players: “Did you, at any occasion during the previous season, have an injury, pain or symptoms in the hip and groin region that completely prevented you from training or match play (made you miss a match or training)?” We assessed seasonal prevalence of non-time loss problems by asking players: “Did you, at any occasion during the previous season, have an injury, pain or symptoms in the hip and groin region that affected you during training and match play (i.e. you were able to participate in matches/trainings, but meanwhile had symptoms/pain in hip/groin that affected your performance)?”. The duration of these problems was assessed by asking players for how many weeks they were unable to participate (time loss) or for how many weeks they were affected by these problems (non-time loss). Furthermore, the survey collected current self-reported hip and groin function assessed by the Copenhagen Hip and Groin Outcome Score [HAGOS; Subscales: pain, symptoms, activity of daily living (ADL), sport, physical activity (PA), and quality of life (QOL)].²¹

Data management and statistics

Data analysis was performed using SPSS Statistics 23 (IBM Software). Descriptive statistics were presented in form of frequencies [percentage (95%CI)] for nominal data, and median [interquartile range (IQR)] or means [standard deviations (SD)] for ordinal and ratio scale data.

HAGOS scores were computed and transformed to a 0-100 scale (0 representing extreme hip and/or groin problems and 100 representing no hip and/or groin problems) for each domain (Pain, Symptoms, ADL, Sport, PA, QOL). Duration of problems (including both non time-loss and time-loss problems) were categorized into short duration (1-2 weeks), medium duration (3-5 weeks), or longstanding (≥6 weeks). Differences in HAGOS scores in the beginning of the season between players with and without hip and groin problems (including both non-time loss and time-loss problems) during the previous season were analyzed with Mann-Whitney U test.

RESULTS

Sixty-nine players participated in the study. Inflow of players into the study is illustrated in Figure 1 and their demographics is described in Table 1.

Figure 1.

Flow of participants into the study

Table 1.

Player demographics (n=69)

Age in years [Mean (SD)]	22.0 (4.8)
Height (cm) [Mean (SD)]	169 (6.2)
Weight (kg) [Mean (SD)]	67.8 (7.2)
Years playing ice hockey [Mean (SD)]	5.8 (4.8)
Playing position [% (n)]
Goalkeeper	27.5 (19)
Defender	26.1 (18)
Forward	46.4 (32)

SD = Standard deviation; cm = centimeters; kg = kilogram

Seasonal prevalence

Two thirds of all players [n = 43; 62.3% (95%CI: 50-74)] had experienced hip and groin problems affecting their performance during the previous season [median duration: 3 weeks (IQR: 3-4)]. More than a quarter of all players [n=18; 26.1% (95%CI: 17-38)] experienced hip and groin problems leading to time-loss [median duration: 1.5 weeks (IQR: 1-2.25)].

Problem duration

The majority of hip and groin problems were of short (1-2 weeks) or medium duration (3-5 weeks), and just three players reported longstanding problems (≥6 weeks) (Figure 2). Players that had experienced hip and groin problems during the previous season presented with significantly impaired self-reported function in the beginning of the new season (Table 2 & Figure 3).

Figure 2.

Distribution of players with different duration of hip and groin problems

Table 2.

HAGOS profiles for players with and without hip and groin pain in the previous season (n=69)

HAGOS-subscales	Hip and groin pain in previous season (n=43) [Median (IQR)]	No hip and groin pain in previous season(n=26) [Median (IQR)]	P-value*
Pain	87.5 (77.5-95.0)	96.3 (88.8-100.0)	0.011
Symptom	71.43 (53.57-78.57)	89.28 (78.57-93.75)	0.000
ADL	90.00 /(75.00-100.00)	100.00 (95.00-100.00)	0.007
Sport	75.00 (59.38-93.75)	96.88 (83.59-100.00)	0.001
PA	100.00 (100.00-75.00)	100.00 (100.00-100.00)	0.004
QoL	75.00 (55.00-90-00)	97.50 (88.75-100.00)	<0.001

HAGOS = Copenhagen Hip and Groin Outcome Score; IQR = Interquartile range; ADL = Activities of daily living; PA = Physical activity; QoL = Quality of life * Man-Whitney U test

Figure 3.

HAGOS profiles for players with and without experienced hip and groin problems during the previous season. For below the table: HAGOS = Hip and Groin Outcome Score; ADL = Activities of daily living; PA = Physical activity; QoL = Quality of life

DISCUSSION

The current study is the first to investigate the magnitude and burden of hip and groin problems in professional female ice hockey players. Two out of three players had experienced hip and groin problems during the previous season that negatively affected their self-reported performance. A quarter of the players had experienced hip and groin problems leading to time loss. There was a low prevalence of longstanding hip and groin problems (≥6 weeks), but players with self-reported problems during the previous season had significant impairments in self-reported function in the beginning of the new season.

Two-thirds of players in this study reported having had problems during the previous season. According to these results, about 13 out of 20 players in a regular female hockey squad can expect to experience hip and groin problems over the course of a season. Most of the experienced problems did not lead to time loss from ice hockey. This is consistent with previous research suggesting that overuse injuries, characterized by gradual onset, are dominating the injury landscape for female NCAA players.²² Surveillance methods used in previous studies rely on the player to report an injury to medical officials or athletic trainers who are then expected to report the injury.^1,8,9,11-14 Players may continue playing despite suffering from an overuse injury,¹⁶ and reporting by medical officials and athletic trainers is done on a voluntary basis.²³ Therefore, like other overuse injuries, hip and groin problems are likely to be systematically underreported in the current literature.¹⁵ On the other hand, a recent study showed that injury surveillance may also be subject to systematic overreporting when third parties such as research invested clinicians are involved in data collection.²⁴ By letting the players themselves report the prevalence of these problems, irrespective of whether or not they had to cease ice hockey participation, results of this study may provide a first step towards a more accurate description of their magnitude.

In this study, the severity of self-reported hip and groin problems is expressed by their duration and association with hip and groin function in the beginning of the new season. Traditionally, injury severity is expressed by the number of days lost from sport participation, which is argued against in the description of overuse problems like hip and groin problems.¹⁶ In this study, long-lasting hip and groin problems were rare and the majority of affected players had problem durations between one and six weeks. However, despite not being labeled as long-lasting, these problems were associated with reduced hip and groin function in the beginning of the new season. Players with problems in the previous season reported significantly worse function on all HAGOS subscales but the impairments were most marked for the three subscales symptoms, sport, and quality of life. Hip and groin pain is strongly related to self-reported sporting function in ice hockey players,²⁵ and questionnaire items dealing with sport participation and quality of life have been rated the most important by patients with hip and groin problems.^21,26 In their study on soccer players, Thorborg and colleagues¹⁸ showed similar results to the results in this study, highlighting the fact that hip and groin problems may have a long-lasting impact on the players’ hip and groin function. It has to be acknowledged that the study by Thorborg et al.¹⁸ included a larger sample and had far better response rates. Nevertheless, both studies indicate that, despite end of the season, long summer break, and pre-season training, players with problems during the season still present with meaningful impairments in self-reported function in the beginning of the new season, when they are expected to perform at their best.

This study is the first to describe hip and groin problems in a sample of female ice hockey players on the highest national level. In the absence of comparable data, the underlying study can be considered to be a first step towards an understanding of the scope of hip and groin problems in professional female ice hockey players. Though the absolute size of the sample is small, and the response rate for skaters low, its relative size is considered appropriate in relation to the underlying population. The sample includes 79% of all goalkeepers active in the highest Swedish hockey league, but the 25% response rate from skaters (defenders and forwards) was quite low. It is possible that skaters with a history of hip and groin problems were more likely to respond to the survey and thereby introduced a selection bias leading to an overestimation of these problems. It also has to be acknowledged that accuracy of the reported prevalence may have been affected by the fact that players had to recall hip and groin problems in the past season. Even though previous research has shown that athletes can provide valid reports of injury history one year in retrospect,²⁷ prospective studies on hip and groin problems, similar to recent work on football players,¹⁷ are warranted in professional female ice hockey players. In the current study, seasonal prevalence of hip and groin problems was reported by the athletes themselves. It can be discussed how the validity of these reports compares to injuries reported by medical officials. However, a recent study on elite athletes reveals that a reported injury might only be the end-result of a context-dependent process in which athletes perceive to be injured once a problem starts to hamper performance and participation.¹⁰ In agreement with these findings, the underlying study investigates the athlete's perception of an injury beyond an official injury report or time-loss. Future prospective studies should make the next step and describe severity of these problems with measures of the athletes’ function such as the Oslo Sports Trauma Research Center (OSTRC) overuse injury questionnaire.²⁸ Another important consideration is that no clinical examinations or classifications of reported problems according to consensus-based terminology⁷ were performed. However, the classification of hip and groin problems is subject to clinical uncertainty⁷ and due to the geographical spread of players across Sweden, and the lack of medical support for female players, it was not possible to perform these standardized physical examinations.

Athletes, coaches, and clinicians all have one common goal – optimizing performance and not getting injured while doing so.²⁹ Results from the current study indicates that 60% of professional female ice hockey players experience hip and groin problems during a season, and those problems seem to impair the players’ ability to perform. By reducing the risk for these injuries and maintain high levels of performance, there is hence a chance to kill two birds with one stone. Problems not leading to time-loss where most common and we observed longer duration of problems to be associated with subsequent impairments in function. These results indicate that preventive efforts should not only be focused on keeping healthy players injury free (primary prevention) but also on discovering existing problems early and keep their duration as short as possible (secondary prevention). There are clinical tools to modify risk factors such as impaired adductor strength,³⁰ which have shown to reduce injury risk in other sports,³¹ as well as clinical tools to screen for existing problems in ice hockey players.²⁵ It is time to change the game plan and play in the offensive zone.

CONCLUSION

Two-thirds of all professional female ice hockey players had experienced hip and groin problems during the previous season, which led to time-loss for one in four of these players. Longstanding hip and groin problems were rare but self-reported hip and groin function was significantly impaired for players that had experienced problems during the previous season. Results of this study indicate that hip and groin problems are a common, not self-determining, problem in professional female ice hockey players.