Comparison of knee joint function, dynamic balance and unilateral jump performance between female and male handball players at least six months after anterior cruciate ligament reconstruction: A cross-sectional study

Handball is among the high-risk sports for anterior cruciate ligament (ACL) rupture. Female athletes have an up to five times increased injury risk compared to male athletes. The incidence of an ACL- reconstruction is 46/100.000 persons/year. Frequently, long-lasting functional deficiencies occur following surgery, including a feeling of joint instability, that may be associated with reduced neuromuscular control. Dynamic balance and performance in several unilateral hop tests are considered important indicators for the risk of re-injury of the lower extremity. In this regard, sex-specific differences in handball players following ACL-reconstruction were not investigated yet. The aim of the present study was to compare knee joint function, dynamic balance, and unilateral jump performance between female and male handball players at least six months after ACL-reconstruction. Methods: Knee function, dynamic balance, and unilateral jump performance were assessed in ten female handball players [mean (± SD) = 27.6 ± 4.5 years] and ten male handball players [mean (± SD) = 26.5 ± 3.1 years] – 6 to 16 months after surgery – using the Knee Injury and Osteoarthritis Outcome Score (KOOS), the Y-Balance test (YBT, normalized to leg length in %), and the Single Leg Hop for Distance Test (SLHDT, normalized to body height in %), respectively. Significance of differences (p < 0.05) between female and male handball players was evaluated using the Mann-Whitney U test (KOOS) and the t-test for independent samples (YBT; SLHDT). Furthermore, effect sizes (r; d) were calculated, respectively. Commercial software (IBM SPSS Statistics 25) was used for statistical analyses. Results: There were no significant differences between female and male handball players in all categories of the KOOS (p > 0.05). Female handball players demonstrated significantly better results in the anterior direction of the YBT for both legs [mean (± SD) reconstructed leg: 73.1 ± 6.6 %; mean (± SD) not injured leg: 75.3 ± 5.8 %] compared to male players [mean (± SD) reconstructed leg: 64.9 ± 7.3 %; mean (± SD) not injured leg: 67.8 ± 7.9 %] (p < 0.05; d = 1.23; d = 1.13, respectively) (Table 1). Jump performance was not significantly different between sexes (p > 0.05). Conclusion: Knee joint function and unilateral jump performance seem not to differ between female and male handball players at least six months after ACL-reconstruction. The significantly better result in anterior direction of the YBT in female handball players may account for a better neuromuscular control or a generally better flexibility of the lower extremity compared to male players.