Injury profile and injury risk factors in junior tennis players

Abstract: The aim of the present investigation was to prospectively study injuries sustained by a cohort of junior players at all levels in a typical tennis club with respect to gender, anatomic location of injuries, type of injuries, and their degree of severity as well as cause of injuries, injury occasion and time of the year when injured. A further aim was to evaluate potential intrinsic as well as extrinsic injury risk factors in the same junior tennis players. All 12-18 years old members in a tennis club playing more than twice weekly were asked to participate. Fifty-five junior tennis players, 35 boys and 20 girls accepted to participate. All fifty five players answered a questionnaire about training habits, time of exposure, previous injuries and equipment factors. A battery of clinical tests and functional performance tests were also carried out. All tennis-related injuries that occurred during a two year period were identified and recorded. An injury was defined as an injury if it was impossible to participate in regular tennis training or playing matches during at least one occasion, which is referred to as a time loss injury. Potential injury risk factors were tested in a multiple stepwise logistic regression model. Thirty-nine players sustained totally 100 new and recurrent injuries, 73 injuries in boys and 27 injuries in girls. Injury incidence for both genders was 2.3 injuries/1000 hours of tennis playing time, for boys 1.7 injuries/1000 hours and for girls 0.6 injuries/1000 hours. Injuries to the lower extremity were the most common ones (51%) followed by the upper extremity (24%) and the trunk (24%). Ankle sprains, low back pain and knee injuries were the most common ones. Sixty-five percent were new injuries and the majority of these injuries were located at the knee joint followed by the ankle joint, while most of the recurrent injuries were found in the lumbar spine. Boys suffered mainly from low back pain and ankle injuries and girls from low back pain and knee injuries. Forty-three percent of the injuries caused absence from tennis for more than four weeks and 31 % more than one week. The most commonly injured body part in the severe category was for both genders the knee joint followed by the lumbar spine and foot/toe (girls). The average number of injury days was 132 (SD 101.5) for boys and 93 (SD 80.4) for girls. Injured players performed more singles per week (p<0.0001) and played more tennis hours per year (p=0.016) than the uninjured players. Playing tennis more than six hours/week was found to be a risk factor for back pain. A previous injury regardless of location was identified as an injury risk factor, and a previous injury to the back was a risk factor for back pain. In conclusion, the injury incidence in junior tennis players is relatively low. New injuries were mainly found in the knee joint, followed by the ankle joint, while most recurrent injuries were localized to the lumbar spine. The majority of tennis related injuries in boys consisted of low back pain and injuries to the ankle joint, while low back pain and injuries to the knee joint were most frequent in girls. More than 40% of the injuries were considered to be severe and 30% were classified as moderate. Further on we conclude that a previous injury regardless of body location was found to be an injury risk factor. In addition, a previous injury to the back and playing tennis more than six hours per week were identified as risk factors for back pain.