Does radiographic location ensure precise anatomic location of the femoral fixation site in medial patellofemoral ligament surgery?

Abstract

IV.

Radiographic Reference Points Are Inaccurate With and Without a True Lateral Radiograph

“…When considering an overlap area .50% of the anatomic tunnel area to be reasonable, they reported a substantial rate of malposition, with only 33% and 17% of knees having .50% overlap with the methods defined by Schöttle et al 32 and Stephen et al, 45 respectively. The findings of the current study appear consistent with those of Sanchis-Alfonso et al, 31 given that the average distance between the anatomic MPFL attachment center and the radiographic point was 4.1 mm on a true lateral radiograph, leaving a maximum theoretical overlap of 2.9 mm based on standard 7-mm tunnels. Therefore, similar to the studies of Redfern et al 30 and Sanchis-Alfanso et al, 31 the current study found tunnel malposition to occur on true lateral imaging using the Schöttle et al 32 technique.…”

“…Therefore, similar to the studies of Redfern et al 30 and Sanchis-Alfanso et al, 31 the current study found tunnel malposition to occur on true lateral imaging using the Schöttle et al 32 technique. In contrast, however, neither Redfern et al 30 nor Sanchis-Alfanso et al 31 assessed how this malposition potentiated with deviation from true lateral radiographs. These findings are notable given the wide use of radiographic methods in clinical practice, particularly that defined by Schöttle et al 32 With studies reporting malposition of as little as 5 mm significantly altering graft isometry, medial patellar tilt, and peak medial patellofemoral pressure, 13,39,45 it is understandable how aberrant lateral imaging during percutaneous MPFL femoral tunnel placement can potentiate tunnel malposition.…”

“…4,16,49 Knees with anatomic anomalies such as patella alta, trochlear dysplasia, quadriceps dysplasia, patellar tilt, and anterior tibial tubercle lateralization have a reported high association with symptomatic patellar instability when compared with control knees 11 and may also have altered ME and ATT anatomy as suggested by Servien et al 34 Recent studies 16,31 reported great anatomic variability of the ATT position assessed with computed tomography (CT) scans. Likewise, Sanchis-Alfonso et al 31 argued against the use of radiographic methods, as they do not account for anatomic variations in medial knee anatomy, particularly the ATT, thereby reflecting an added risk for malposition. Although variability in the ATT position was also observed in this study, its distance relative to the MPFL attachment was fairly consistent, averaging 7.9 6 1.2 mm.…”

A prospective randomized trial evaluating two different tensioning techniques for medial patellofemoral ligament reconstruction

“…In fact, the tunnel malposition may change the mechanical tension and pattern and affect the clinical outcome. Fortunately, with more and more detailed understanding of MPFL anatomy, the anatomical placement of the femoral tunnel can be reached by unequivocally identifying the most important anatomic landmark, the adductor tubercle and femoral epicondyle [25]. Therefore, graft tension has become the greatest concern for successful MPFL reconstruction.…”

Femoral insertion site in medial patellofemoral ligament reconstruction

“…Anatomic landmarks and radiographic orientation can assist the surgeon in finding the appropriate femoral fixation point [23,26], but is not sufficient alone in defining the subject specific MPFL point [35]. An additional dynamic testing of the ligament tension over the full range of motion during surgery is mandatory with an adjusting of the site of anchorage if needed.…”