ISAKOS: 2019 Congress in Cancun, Mexico

2019 ISAKOS Biennial Congress ePoster #748


Analysis of Factors Affecting the Surgical Time in Anterior Cruciate Ligament Reconstruction Using Decision Tree Analysis

Kengo Harato, MD, PhD, Tokyo JAPAN
Shu Kobayashi, MD, PhD, Tokyo JAPAN
Kazuya Kaneda, MD, Shinjuku, Tokyo JAPAN
Yu Iwama, MD, Tokyo JAPAN
Masaki Nagashima, MD, PhD, Mitaka, Tokyo JAPAN
Takayuki Hasegawa, MD, Tokyo JAPAN
Yutaro Morishige, MD, Tokyo JAPAN
Eri Katsuyama, MD, Shinjuku, Tokyo JAPAN
Takashi Toyoda, MD, PhD, Tokyo JAPAN
Yasuo Niki, MD, PhD, Tokyo JAPAN

Dept. of Orthopaedic Surgery, Keio University School of Medicine, Tokyo, JAPAN

FDA Status Not Applicable


The purpose of the present study was to clarify the important factors affecting a surgical time in ACL reconstruction using decision making tree analysis, and the conclusion was that the most important factor was surgeon volume and well experienced assistants were required in the surgery done by non-high volume surgeons for the appropriate surgical time.



A longer surgical time will lead to postoperative complications in orthopedic surgery. According to previous reports, surgeon volume affects a surgical time in anterior cruciate ligament (ACL) reconstruction. However, little attention has been paid to factors affecting a surgical time in ACL reconstruction. The purpose was to clarify the important factors affecting a surgical time in ACL reconstruction using decision making tree analysis.


A total of 105 knees (52 females, 53 males) averaged 29.3 years, were enrolled. All knees were diagnosed as ACL injury based on physical assessment and MRI findings. All procedures were done using arthroscopy by 13 surgeons at 7 facilities with a same implant (TightRope RT®, Arthrex). All surgeries were done using the same steps, which consisted of Hamstrings tendon harvest, joint assessment using arthroscopy, bone tunnel creation, graft preparation, graft passage, and fixation on the tibial cortex. Revision surgery and complex meniscal injury were excluded. The present investigation was conducted as a retrospective study. All methods and procedures were approved by our institution's ethics committee. Factors, including age, sex, body mass index, surgeon annual volume, assistant annual volume as a surgeon, number of assistants, bone tunnel creation method (outside-in, transtibia, transportal), and reconstruction procedure (single or double bundle) were assessed in each surgery. Surgeons and assistants were divided into two groups based on surgical volume (Group High Volume [HV]: annual ACL reconstruction = 50 cases, Group Non-High Volume [NHV]: annual ACL reconstruction < 50 cases). Those annual volume and surgical information were changed into dummy variables. In the statistical analysis, decision tree analysis by Classification and Regression Tree was performed using surgical time as a dependent variable and others as independent variables.


First of all, surgeon volume was extracted. Average surgical times in Group HV and NHV were 88.2 and 131.7 minutes, respectively. As a second selection, reconstruction procedure was extracted in Group HV. Third selection showed that number of assistants was important in single bundle reconstruction performed by HV surgeons. The shortest surgery was single bundle reconstruction performed by HV surgeons with two assistants and the shortest time averaged 80.5 minutes. In Group NHV, assistant annual volume was extracted as a second selection. Third selection showed that bone tunnel creation method was important in surgery performed by NHV surgeons with HV assistants. The longest surgery was ACL reconstruction performed by NHV surgeons with one NHV surgeon and the longest time averaged 218.3 minutes.


From the present study, the most important factor affecting a surgical time was surgeon volume. To reduce a surgical time, reconstruction procedure, bone tunnel creation method and number of assistants were important in ACL reconstruction done by HV surgeons. On the other hand, experience of assistants was essential to reduce a surgical time in ACL reconstruction done by NHV surgeons, compared to other parameters.


To acquire the appropriate surgical time of ACL reconstruction, the most important factor was surgeon volume. If non-high volume surgeon performed the surgery, experience of assistants was mandatory to reduce a surgical time.