Saddle sulcus may be an accurate reference point for MPFL femoral tunnel placement
Compared with radiographic reference points, the position of the saddle sulcus may be a more reliably accurate landmark for lateral medial patellofemoral ligament tunnel placement, according to published results.
In a laboratory study, researchers analyzed previously reported radiographic reference points in nine fresh-frozen, unpaired human cadaveric knees based on intraoperative true lateral radiographs and 3D imaging. According to the study, they marked MPFL insertion points and relative osseous structures, such as the saddle sulcus, to determine the most accurate reference for femoral MPFL tunnel placement.
Researchers found the precise position of the saddle sulcus according to the medial epicondyle (ME) and the adductor tubercle (AT) was the most reliable landmark of MPFL attachment. Additionally, the distances from the saddle sulcus to the studied radiographic reference points were 6.2 mm using the Schöttle method, 5.9 mm using the Redfern method and 7.3 mm using the Fujino method.
These malpositions could result “in dramatic increase in patellofemoral pressure and alteration of graft isometry,” the researchers wrote in the study.
“The most important finding of our study was that the saddle sulcus was a reliable landmark where the MPFL was anatomically attached, located at approximately 12 mm from the AT to the ME and 6 mm perpendicular-posterior to the border connecting the apexes of the AT and the ME,” they added.
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Chen and colleagues present a cadaveric study evaluating the MPFL femoral attachment site in relation to nearby osseous anatomy and radiographic reference points.
In the authors’ cadaveric dissections, they identified the saddle sulcus region as the anatomic MPFL femoral attachment. Using CT scan reformats, the saddle sulcus was generally located 6 mm posteriorly to a point 12 mm distally along a line subtended from the adductor tubercle (AT) to the medial femoral epicondyle (MFE). This information provides surgeons with a more straight-forward anatomy-based approach for locating the femoral attachment when reconstructing the MPFL. The authors take their findings one step further by comparing the anatomic saddle sulcus with three radiographic reference points for MPFL reconstruction femoral tunnel placement – points described by Schöttle, Redfern and Fujino. Corroborating prior studies evaluating efficacy of radiographic targeting for MPFL reconstruction, Chen and colleagues found greater than 5 mm deviation between the anatomic MPFL femoral attachment and each of the three tested radiographic reference points. This study enables readers to get closer to recreating native anatomy when performing MPFL reconstructions – an important advantage as the best way to restore the medial patellofemoral complex continues to be delineated.
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