Biomechanical Evaluation of the Medial Stabilizers of the Patella

Abstract

For an anatomic medial-sided knee reconstruction, the individual biomechanical contributions of the medial patellar ligamentous structures (MPFL, MPTL, and MPML) need to be characterized to facilitate an optimal reconstruction design.

Patients with different patellofemoral disorders display a distinct ligament stiffness pattern under instrumented stress testing

“…Despite some interpatient variability, the most representative ligament stiffness patterns (force-displacement curves) for each of the patellofemoral disorder groups—represented in figure 3—corroborate the results obtained for level of force applied, lateral patellar displacement obtained (PP_LT-NS_diff) and stiffness values. As would be expected, in the low linear region, the patella is gradually and proportionally displaced laterally as the force is applied (lower stiffness values are predominant in these earlier stages), whereas after surpassing a certain force level (between F2=21 N or F3=42 N, depending on each group), the lateral patellar displacement slows down as the soft tissues get stiffer, especially in the PPI and OPI groups 22 33. Analysing in more detail, both patients with OPI and PPI display the same curve pattern (steep increase close to the final displacement), but with patients with PPI showing higher stiffness than patients with OPI as would be expected if their medial soft tissue stabilisers are in better condition than the OPI group where the medial restraints have presumably been injured.…”

“…Physical examination, while playing a pivotal role in assessment of the patellofemoral joint, is limited by intraobserver and interobserver variability between examiners 20 21. Several cadaveric studies have studied the biomechanical properties of the medial ligamentous stabilisers of the patellofemoral joint 13 17 22 23. In vitro studies are limited by a lack of the dynamic elements of the patellofemoral joint, which are difficult to duplicate in the laboratory.…”

Editorial Commentary: Medial Patellofemoral Complex: Driving a Better Understanding of Medial Knee Anatomy

“…52 Most of the studies in the last 2 years are in agreement that the MPFC attaches more proximally than we thought, having a connection to the medial border of the vastus intermedius tendon (Table 1). 40,41,[43][44][45]47,49,50 My colleagues and I performed a cadaveric dissection and found similar findings; that MPFC originates from a midpoint between the femoral epicondyle and adductor tubercle. It fans out into 2 bands: a main thick band to the upper half of the patella and a thin upper layer running anteriorly, upward, then under the vastus medialis obliquus.…”

Biomechanical Evaluation of the Medial Stabilizers of the Patella: Letter to the Editor

“…quantification of the biomechanical properties of each individual medial patellar ligament. 1 We congratulate the authors for their excellent work performed on twenty-two fresh-frozen cadaveric knees. We are convinced that the results obtained from this study will enhance anatomic reconstruction techniques in knee surgery.…”