Tibial Tubercle Osteotomy

Tibial tubercle osteotomy (TTO) is a frequently perform procedure for the treatment of patellar instability and allows for chondral defect unloading when performed in conjunction with cartilage repair. Accurate intraoperative execution of the osteotomy is of utmost importance to achieve the desire outcome. The purpose of this study is to validate the intraoperative accuracy of the osteotomy angle of TTO.

However, according to a recently published study, high accuracy of the preoperatively plan osteotomy angle for anteromedialization tibial tubercle osteotomy may be achieved without the use of calibrated guides. Between January 2007 and May 2017, a total of 212 patients underwent TTO; however, only patients with postoperative axial (magnetic resonance) imaging eligible for inclusion. Thus, 124 patients (126 knees) (58.5%) evaluated in this study.

Slightly steeper angles

The osteotomy angle assessed by two independent reviewers (fellowship trained radiologist and orthopaedic surgeon) using MRI and compared with preoperative planning. “The study demonstrated improved accuracy and overall slightly steeper angles than intended, averaging 104.1% of preoperative planning,” the authors wrote. “They believe that good exposure and visualization of the [tibial tubercle] TT intraoperatively are crucial to the precision of the osteotomy cut.”

However, patients were on average 32.89 years (range 15–56, SD 9.7) of age at the time of surgery with an equal gender contribution (50% women vs 50% men). Postoperative MRI was conducted at 12.53 months (range 2–91 months, SD 12.2) follow-up. Postoperative MRI-measured osteotomy angles averaged 104.1% of planned angles and showed a high intraclass correlation coefficient of 0.87. But the accuracy of the osteotomy cut did not vary with the planned steepness of the cut (p=0.984).

Tibial tubercle osteotomy

However, this study demonstrates that the high accuracy of the osteotomy angle can be achieve without the use of calibrated guides. Good exposure and visualisation of the TT intraoperatively are paramount for the precision of anteromedialisation TT osteotomy; using the Fulkerson’s technique. Researchers evaluated 124 patients who underwent tibial tubercle osteotomy. During preoperative planning, investigators calculated the needed amount of medialization based on the preoperative tibial tubercle-trochlear groove (TT-TG). Two independent reviewers assessed the osteotomy angle with MRI at 12.53 months follow-up and compared it with the preoperatively planned angle.

Results showed postoperative MRI-measured osteotomy angles, on average, were 104.1% of planned angles. Investigators noted the MRI-measured osteotomy angles showed a high intraclass correlation coefficient of 0.87. Accuracy of the osteotomy cut did not vary compared with the planned steepness of the cut. This study demonstrates that the high accuracy of the osteotomy angle achieved without the use of calibrated guides. Good exposure and visualisation of the TT intraoperatively are paramount for the precision of anteromedialisation TT osteotomy using the Fulkerson’s technique.