- This study was the first to examine whether there is any difference between the radiographic positions corresponding to the medial quadriceps tendon–femoral ligament (MQTFL) and medial patellofemoral ligament (MPFL) fibers on the femur
- On fluoroscopy, the most proximal MQTFL and most distal MPFL fibers had significantly different radiographic positions from the medial patellofemoral complex (MPFC) midpoint on the femur
- The MPFC footprint exists as more than a single radiographic point, so separate radiographic parameters may be needed for anatomic MPFL versus MQTFL reconstruction
The understanding of the medial patellofemoral complex (MPFC) has been changing. Still, the current view is that it consists of the medial patellofemoral ligament (MPFL) and the medial quadriceps tendon–femoral ligament (MQTFL). Reconstruction of either component can restore patellar stability.
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Proper anatomic femoral tunnel placement in these procedures is key to avoiding complications and poor outcomes. During MPFL reconstruction, the radiographic midpoint of the MPFC attachment on the femur is often used intraoperatively for optimal tunnel positioning.
However, researchers at Massachusetts General Hospital have discovered that the most proximal MQTFL fibers and the most distal MPFL fibers are not interchangeable with that landmark. In Arthroscopy, Rohan Bhimani, MD, MBA, a research fellow in the Department of Orthopaedic Surgery, Miho J. Tanaka, MD, orthopedic surgeon and director of the Women's Sports Medicine Program, and colleagues present guidance about how MPFC reconstruction may need to be adapted.
The researchers studied eight unpaired human cadaveric specimens (three from male cadavers, five from females, mean age 52). They identified the proximal MQTFL and distal MPFL attachments of the MPFC to the femur and marked them with pins.
Lateral fluoroscopic images of the femur were then obtained. The radiographic positions of the proximal and distal margins of the MPFC footprint were identified, and the midpoint between these points was calculated and marked.
Using radiographic landmarks previously described in The American Journal of Sports Medicine, each point was described relative to the posterior cortical line of the femur and a line perpendicular to that line, through the proximal margin of the posterior condyle. Measurements were taken as orthogonal distances from these reference lines and a direct distance from the intersection of the two reference lines.
When fluoroscopic measurements were taken of the MPFC attachment on the femur, the means were:
- Proximal MQTFL footprint—0.8 mm anterior (P=0.013) and 5.2 mm proximal (P<0.001) to the radiographic MPFC midpoint
- Distal MPFL footprint—0.8 mm posterior (P=0.012) and 5.9 mm distal (P<0.001) to the midpoint
- Radiographic point corresponding to the distal MPFL footprint—0.8 mm posterior (P=0.011) and 11.1 mm distal (P<0.001) to the radiographic point corresponding to the proximal MQTFL footprint
When the intersection between the posterior cortical line and the proximal posterior condyle was used as a radiographic landmark:
- The midpoint of the MPFC was a mean of 3.8 mm from the landmark
- The mean radiographic points corresponding to the MQTFL and MPFL footprints were 6.5 mm and 7.2 mm from the landmark, respectively
- Overall, 92% of points corresponding to the MPFC midpoint, MQTFL, and MPFL were within 10 mm of the landmark
When reconstructing a component of the MPFC, arthroscopists should consider that separate radiographic parameters may be needed for anatomic MPFL versus MQTFL reconstruction. In addition, using both anatomic and radiographic landmarks, combined with an assessment of graft isometry, is advisable.
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