Does the use of fluoroscopy and isometry during anterior cruciate ligament reconstruction affect surgical decision making?

Objective: Poor results after anterior cruciate ligament (ACL) reconstruction are often due to inaccurate graft placement. Numerous strategies have been advocated to improve accuracy and consistency of tunnel positioning, including computer-assisted navigation. Less expensive alternatives, such as intraoperative fluoroscopy and isometry, have also been advocated for confirming guide pin placement before reaming the femoral tunnel. It is unknown how often these techniques cause surgeons to change the location of their femoral tunnel at the time of surgery. We undertook this study to determine how often this approach results in repositioning of the guide pin before final graft placement. We hypothesized that a lower level of surgeon experience would lead to a higher frequency of repositioning compared to a higher level of experience.

Design: Prospective, case series.

Setting: Institutional.

Patients: Intraoperative data were gathered prospectively from 413 consecutive, primary ACL reconstructions performed by the sports medicine group at our institution. Of the 413 procedures enrolled in this study, 407 were available for analysis. Six procedures were excluded because the tension isometer was unavailable during the procedure.

Interventions: Isometry and fluoroscopy were used in all cases to aid in the accurate placement of the femoral tunnel. Femoral pin change based on the results of isometry or fluoroscopy was recorded. The percentage of cases involving a change in the femoral pin resulting from the use of these techniques was calculated. This percentage was also calculated separately for cases performed by a staff surgeon (fellowship-trained sports medicine staff) as well as less experienced surgeons (current sports medicine fellows).

Main Outcome Measures: The main outcome measurement was whether the femoral pin was changed.

Results: Of the 407 procedures available for review, 62 (15%) of them involved a change in femoral pin position secondary to information provided by intraoperative isometry or fluoroscopy. In the procedures performed by more experienced surgeons, the pin was changed in 40 (16%) of 253 cases; in those performed by less experienced surgeons, it was changed in 22 (14%) of 154 cases.

Conclusions: The intraoperative use of isometry and fluoroscopy during ACL reconstruction led to changes in the femoral tunnel placement 15% of the time. The influence of these instruments on intraoperative decision making does not seem to diminish with surgical experience.