Prevention of Groin Injuries in Sports
The initial search identified 1747 unique references (figure 1). After exclusion by title and abstract, 33 were read in full text. From the 33 articles, 26 were excluded. The most common reason for exclusion (15 studies) was that studies did not report the incidence of groin injuries in isolation. Eleven studies were not RCTs and were therefore also excluded. Finally, seven studies were included.
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Figure 1.
Flow chart of included studies.
The most relevant characteristics of the seven included studies are summarised in Table 1. For detailed information on study design, participants, exposure and statistics see online supplementary web-appendix 2 http://bjsm.bmj.com/content/49/12/785/suppl/DC1. Six studies were cluster-randomised controlled trials, where teams or clubs were the unit of randomisation, while one study performed randomisation at the individual level. In total, the included studies involved 4648 participants. Three studies reported exposure data. Among cluster-randomised trials, one study was adjusted for clustering effects, reporting an ICC value equal to zero. Compliance reports were not specified according to prescribed or optimal dosage (see Table 1) and only three studies reported intention-to-treat data.
Time-loss groin injury definition was used in six of the seven included studies, while the last study used time-loss as well as medical-attention definitions. The authors of two studies were contacted to provide extra data for exposure, age of participants and number of groin injuries. Data from van Beijsterveldt et al were obtained, but exposure data from Hölmich et al were not available. Results of the risk of bias assessment are presented in meta-analysis figures (figure 2A–F). Specific justification for each assessment is included in online supplementary web-appendix 2 http://bjsm.bmj.com/content/49/12/785/suppl/DC1.
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Figure 2.
(A) Primary analysis including all seven studies. (B) Subgroup analysis based on type of sport. (C) Subgroup analysis based on gender (only women). (D) Subgroup analysis based on gender (only men). (E) Subgroup analysis based on type of preventative programme (active adductor strength programme). (F) Subgroup analysis based on type of preventative programme ('The 11').
In total, 4191 players were included in the primary analysis. For the primary outcome, number of groin injuries in the control group versus the intervention group, the effect estimates based on 157 injuries (figure 2A), was RR 0.81 (95% CI 0.60 to 1.09; I=7% χ p=0.37).
The study on handball players did not report any groin injuries. The subgroup analysis on type of sport (figure 2B), therefore, included the remaining six football studies, which showed an effect estimate of RR 0.81 (95% CI 0.60 to 1.09; I =7% χ p=0.37).
A gender specific subgroup analysis of two football studies conducted among female players, including active exercise programmes (figure 2C), showed an estimate of RR 0.48 (95% CI 0.20 to 1.13; I =46% χ p=0.17). Pooled data from the three football studies, including active exercise programmes, performed among men (figure 2D), showed an effect estimate of RR 0.84 (95% CI 0.60 to 1.18; I =0% χ p=0.57).
An active adductor strength programme was tested in two studies, with a pooled effect estimate (figure 2E) of RR 0.78 (95% CI 0.49 to 1.25; I =0% χ p=0.34). 'The 11' preventive programme (figure 2F) was tested in two trials, with a pooled effect estimate of RR 0.68 (95% CI 0.40 to 1.14; I =55% χ p=0.13).
Results
Search Results
The initial search identified 1747 unique references (figure 1). After exclusion by title and abstract, 33 were read in full text. From the 33 articles, 26 were excluded. The most common reason for exclusion (15 studies) was that studies did not report the incidence of groin injuries in isolation. Eleven studies were not RCTs and were therefore also excluded. Finally, seven studies were included.
(Enlarge Image)
Figure 1.
Flow chart of included studies.
Description of Studies
The most relevant characteristics of the seven included studies are summarised in Table 1. For detailed information on study design, participants, exposure and statistics see online supplementary web-appendix 2 http://bjsm.bmj.com/content/49/12/785/suppl/DC1. Six studies were cluster-randomised controlled trials, where teams or clubs were the unit of randomisation, while one study performed randomisation at the individual level. In total, the included studies involved 4648 participants. Three studies reported exposure data. Among cluster-randomised trials, one study was adjusted for clustering effects, reporting an ICC value equal to zero. Compliance reports were not specified according to prescribed or optimal dosage (see Table 1) and only three studies reported intention-to-treat data.
Time-loss groin injury definition was used in six of the seven included studies, while the last study used time-loss as well as medical-attention definitions. The authors of two studies were contacted to provide extra data for exposure, age of participants and number of groin injuries. Data from van Beijsterveldt et al were obtained, but exposure data from Hölmich et al were not available. Results of the risk of bias assessment are presented in meta-analysis figures (figure 2A–F). Specific justification for each assessment is included in online supplementary web-appendix 2 http://bjsm.bmj.com/content/49/12/785/suppl/DC1.
(Enlarge Image)
Figure 2.
(A) Primary analysis including all seven studies. (B) Subgroup analysis based on type of sport. (C) Subgroup analysis based on gender (only women). (D) Subgroup analysis based on gender (only men). (E) Subgroup analysis based on type of preventative programme (active adductor strength programme). (F) Subgroup analysis based on type of preventative programme ('The 11').
Total Estimate
In total, 4191 players were included in the primary analysis. For the primary outcome, number of groin injuries in the control group versus the intervention group, the effect estimates based on 157 injuries (figure 2A), was RR 0.81 (95% CI 0.60 to 1.09; I=7% χ p=0.37).
Type of Sport Analysis
The study on handball players did not report any groin injuries. The subgroup analysis on type of sport (figure 2B), therefore, included the remaining six football studies, which showed an effect estimate of RR 0.81 (95% CI 0.60 to 1.09; I =7% χ p=0.37).
Gender Analyses
A gender specific subgroup analysis of two football studies conducted among female players, including active exercise programmes (figure 2C), showed an estimate of RR 0.48 (95% CI 0.20 to 1.13; I =46% χ p=0.17). Pooled data from the three football studies, including active exercise programmes, performed among men (figure 2D), showed an effect estimate of RR 0.84 (95% CI 0.60 to 1.18; I =0% χ p=0.57).
Type of Preventive Programme Analyses
An active adductor strength programme was tested in two studies, with a pooled effect estimate (figure 2E) of RR 0.78 (95% CI 0.49 to 1.25; I =0% χ p=0.34). 'The 11' preventive programme (figure 2F) was tested in two trials, with a pooled effect estimate of RR 0.68 (95% CI 0.40 to 1.14; I =55% χ p=0.13).
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