Vibroarthrographic analysis of patellofemoral joint arthrokinematics during squats with increasing external loads
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(2020) 12:51
RESEARCH ARTICLE
Open Access
Vibroarthrographic analysis of patellofemoral joint arthrokinematics during squats with increasing external loads Ewelina Ołowiana1, Noelle Selkow2, Kevin Laudner3, Daniel Puciato1 and Dawid Bączkowicz1*
Abstract Background: The patellofemoral joint (PFJ) provides extremely low kinetic friction, which results in optimal arthrokinematic motion quality. Previous research showed that these friction-reducing properties may be diminished due to the increase in articular contact forces. However, this phenomenon has not been analyzed in vivo during functional daily-living activities. The aim of this study was the vibroarthrographic assessment of changes in PFJ arthrokinematics during squats with variated loads. Methods: 114 knees from 57 asymptomatic subjects (23 females and 34 males) whose ages ranged from 19 to 26 years were enrolled in this study. Participants were asked to perform 3 trials: 4 repetitions of bodyweight squats (L0), 4 repetitions of 10 kg barbell back loaded squats (L10), 4 repetitions of 20 kg barbell back loaded squats (L20). During the unloaded and loaded (L10, L20) squats, vibroarthrographic signals were collected using an accelerometer placed on the patella and were described by the following parameters: variation of mean square (VMS), mean range (R4), and power spectral density for frequency of 50–250 Hz (P1) and 250–450 Hz (P2). Results: Obtained results showed that the lowest values were noted in the unloaded condition and that the increased applied loads had a significant concomitant increase in all the aforementioned parameters bilaterally (p < 0.05). Conclusion: This phenomenon indicates that the application of increasing knee loads during squats corresponds to higher intensity of vibroacoustic emission, which might be related to higher contact stress and kinetic friction as well as diminished arthrokinematic motion quality. Keywords: Knee joint, Squat, Friction, Crepitus, Contact stress, Biomechanics
Background The knee is one of the most loaded joints within the human organism which results in its considerable susceptibility to injuries and an increased risk of early degeneration of the articular surface [1, 2]. The patellofemoral joint (PFJ) plays a key role in the knee extensor mechanism since the patella, * Correspondence: [email protected] 1 Faculty of Physical Education and Physiotherapy, Opole University of Technology, Prószkowska 76, PL-45-578 Opole, Poland Full list of author information is available at the end of the article
being the largest sesamoid bone, increases the length of the lever arm of the patellar tendon, which improves the quadriceps strength by 30–50% [3]. Additionally, the patella acts as a bony shield for the anterior trochlea and due to its interposed position in the extensor apparatus, protects against excessive friction between the quadriceps tendon and the femoral condyles [4]. An indication that the PFJ adapts to considerable loading is the thickness of the hyaline cartilage. It may reach 6–7 mm thick at
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