The effects of the sagittal plane malpositioning of the patella and concomitant quadriceps hypotrophy on the patellofemoral joint: a finite element analysis.
OBJECTIVE
Anterior knee pain is a common symptom after intramedullary nailing in tibia shaft fracture. Moreover, patellofemoral malalignment is also known to be a major reason for anterior knee pain. Patellofemoral malalignment predisposes to increased loading in patellar cartilage. In the previous study, we have demonstrated the quadriceps atrophy and patellofemoral malalignment after intramedullary nailing due to tibia shaft fracture. In this study, our aim was to clarify the effects of quadriceps atrophy and patellofemoral malalignment with the pathologic loading on the joint cartilage.


METHODS
Mesh models of patellofemoral joint were constructed with CT images and integrated with soft tissue components such as menisci and ligaments. Physiological and sagittal tilt models during extension and flexion at 15°, 30° and 60° were created generating eight models. All the models were applied with 137 N force to present the effects of normal loading and 115.7 N force for the simulation of quadriceps atrophy. Different degrees of loading were applied to evaluate the joint contact area and pressure value with the finite element analysis.


RESULTS
There was increased patellofemoral contact area in patellar tilt models with respect to normal models. The similar loading patterns were diagnosed in all models at 0° and 15° knee flexion when 137 N force was applied. Higher loading values were obtained at 30° and 60° knee flexions in sagittal tilt models. Furthermore, in the sagittal tilt models, in which the quadriceps atrophy was simulated, the loadings at 30° and 60° knee flexion were higher than in the physiological ones.


CONCLUSIONS
Sagittal malalignment of the patellofemoral joint is a new concept that results in different loading patterns in the patellofemoral joint biomechanics. This malalignment in sagittal plane leads to increased loading values on the patellofemoral joint at 30° and 60° of the knee flexions. This new concept should be kept in mind during the course of diagnosis and treatment in patients with anterior knee pain. Definition of the exact biomechanical effects of the sagittal tilting will lead to the development of new treatment modalities.
Orthopedics and Traumatology Department, Ankara Education and Research Hospital, Street 89/3 Bahçelievler/Cankaya, Ankara, 06500, Turkey. ertugrul_aksahin@hotmail.com.
Ertugrul
E
Aksahin
Orthopedics and Traumatology Department, Ankara Education and Research Hospital, Street 89/3 Bahçelievler/Cankaya, Ankara, 06500, Turkey.
Onur
O
Kocadal
Orthopedics and Traumatology Department, Ankara Education and Research Hospital, Street 89/3 Bahçelievler/Cankaya, Ankara, 06500, Turkey.
Cem N
CN
Aktekin
Department of Physical Therapy and Rehabilitation, Biruni University Faculty of Health Science, Istanbul, Turkey.
Defne
D
Kaya
Orthopedics and Traumatology Department, Ankara Education and Research Hospital, Street 89/3 Bahçelievler/Cankaya, Ankara, 06500, Turkey.
Murad
M
Pepe
Orthopedics and Traumatology Department, Ankara Numune Education and Research Hospital, Ankara, Turkey.
Serdar
S
Yılmaz
Orthopedics and Traumatology Department, Antalya Training and Research Hospital, Antalya, Turkey.
H Yalcin
HY
Yuksel
Orthopedics and Traumatology Department, Ankara Numune Education and Research Hospital, Ankara, Turkey.
Ali
A
Bicimoglu
D001284:Atrophy / Q000503:physiopathology; D001696:Biomechanical Phenomena; D017760:Bone Malalignment / Q000503:physiopathology*; D002358:Cartilage, Articular / Q000503:physiopathology; D020342:Finite Element Analysis; D006801:Humans; D007719:Knee Joint / Q000503:physiopathology*; D008953:Models, Anatomic; D010329:Patella / Q000473:pathology / Q000503:physiopathology* / Q000601:surgery; D057071:Patellofemoral Joint / Q000503:physiopathology* / Q000601:surgery; D052097:Quadriceps Muscle / Q000473:pathology*; D016059:Range of Motion, Articular / Q000502:physiology
Finite element; Loading; Patellofemoral; Tibia