KNEE Gender differences following computer-navigated single- and double-bundle anterior cruciate ligament reconstruction S. Aldrian • P. Valentin • B. Wondrasch • I. Krusche-Mandl • R. C. Ostermann • P. Platzer • M. Hofbauer Received: 9 October 2012 / Accepted: 24 August 2013 Ó Springer-Verlag Berlin Heidelberg 2013 Abstract Purpose Female patients not only demonstrate an increased risk for injury, but also a poorer response fol- lowing anterior cruciate ligament (ACL) rupture. However, no study has investigated gender-related differences between computer-navigated single-bundle (SB) and dou- ble-bundle (DB) ACL reconstruction. The aim of this study was to evaluate the effects of gender on the outcome of computer-navigated SB and DB ACL reconstruction and to present reference values. Methods A retrospective review of 55 consecutive patients who underwent SB (15 males, 12 females) and DB (18 males, 10 females) ACL reconstruction with autoge- nous hamstring tendon grafts and showed a minimum follow-up of 24 months was conducted. Intraoperatively, the anteroposterior and rotational laxity were measured and the follow-up examination included pivot-shift testing, KT- 1000 arthrometer testing, International Knee Documenta- tion Committee (IKDC) form, the Lysholm score and Tegner score. Results Pre-operatively, female patients showed a sig- nificant higher internal rotation in (p \ 0.001) both the SB and DB group. Regarding the post-operative reduction in internal rotation, females in the SB group revealed a greater reduction compared to males (p \ 0.001), whereas females in the DB group revealed a significantly greater post-operative reduction in anterior–posterior translation (p = 0.04). Female patients following DB ACL recon- struction presented a significant worse IKDC score, Lys- holm score and Tegner score compared to male patients. All score values of the female DB group were worse than in the female SB group. In contrast, male patients showed better results of all examined clinical scores following DB procedure compared to SB technique. Conclusion Female patients who underwent computer- navigated DB ACL reconstruction exhibited significantly worse outcome scores than males who underwent DB ACL reconstruction. The gender-based relationship between joint function and outcome after ACL reconstruction remains unclear and requires further investigation. Level of evidence Retrospective case–control series, Level III. Keywords Gender differences Á Computer navigation Á Anterior cruciate ligament (ACL) Á Hamstrings Á Single bundle Á Double bundle Introduction Anterior cruciate ligament (ACL) injury is the most com- mon knee ligament injury sustained by active individuals, and ACL reconstruction has become one of the most fre- quently performed procedures in orthopaedic surgery [7]. However, several prospective series and meta-analyses have shown that, despite correct tunnel placement, a sig- nificant number of patients experience persistent instability S. Aldrian (&) Á I. Krusche-Mandl Á R. C. Ostermann Á P. Platzer Á M. Hofbauer Department of Trauma Surgery, General Hospital, Medical University Vienna, Wa ¨hringer Gu ¨rtel 18-20, 1090 Vienna, Austria e-mail: silke.aldrian@meduniwien.ac.at P. Valentin Private Department of Trauma Surgery, Rathausplatz 23, 3400 Klosterneuburg, Austria B. Wondrasch Vienna Sports Medicine Center, Wa ¨hringerstrasse 3/10, 1090 Vienna, Austria 123 Knee Surg Sports Traumatol Arthrosc DOI 10.1007/s00167-013-2649-y