Relationship between varus-valgus alignment and patellar kinematics in individuals with knee osteoarthritis

ArticleinThe Journal of Bone and Joint Surgery 89(12):2723-31 · January 2008with17 Reads
DOI: 10.2106/JBJS.F.01016 · Source: PubMed
Abnormal varus-valgus alignment is a risk factor for patellofemoral osteoarthritis, but tibiofemoral alignment alone does not explain compartmental patellofemoral osteoarthritis progression. Other mechanical factors, such as patellar kinematics, probably play a role in the initiation and progression of the disease. The objective of this study was to determine which three-dimensional patellar kinematic parameters (patellar flexion, spin, and tilt and patellar proximal, lateral, and anterior translation) are associated with varus and valgus alignment in subjects with osteoarthritis. Ten individuals with knee osteoarthritis and varus (five subjects) or valgus (five subjects) knee alignment underwent assessment of three-dimensional patellar kinematics. We used a validated magnetic resonance imaging-based method to measure three-dimensional patellar kinematics in knee flexion while the subjects pushed against a pedal with constant load (80 N). A linear random-effects model was used to test the null hypothesis that there was no difference in the relationship between tibiofemoral flexion and patellar kinematics between the varus and valgus groups. Patellar spin was significantly different between groups (p = 0.0096), with the varus group having 2 degrees of constant internal spin and the valgus group having 4.5 degrees of constant external spin. In the varus group, the patellae tracked with a constant medial tilt of 9.6 degrees with flexion, which was significantly different (p = 0.0056) from the increasing medial tilt (at a rate of 1.8 degrees per 10 degrees of increasing knee flexion) in the valgus group. The patellae of the valgus group were 7.5 degrees more extended (p = 0.0093) and positioned 8.8 mm more proximally (p = 0.0155) than the varus group through the range of flexion that was studied. The pattern of anterior translation differed between the groups (p = 0.0011). Our results suggest that authors of future large-scale studies of the relationships between knee mechanics and patellofemoral osteoarthritis should not rely solely on measurements of tibiofemoral alignment and should assess three-dimensional patellar kinematics directly.
    • "Biomechanical studies revealed that a varus-or valgus alignment of the leg axis has significant influence on patellar tracking [40]. Valgus alignment of the leg by just a few angular degrees leads to a lateralisation of the patella and also to a modified patellar tilt [40]. Currently there are no studies with a larger number of cases available. "
    [Show abstract] [Hide abstract] ABSTRACT: To date there is no classification of patellar dislocations considering clinical and radiological pathologies. As a result many studies mingle the dislocation's underlying pathologies, so that there are no consistent therapy recommendations. It is this article's objective to introduce a patellar dislocation classification based on the current literature to allow for the application of a structured diagnosis and treatment algorithm. The classification is based on instability criteria as well as on clinical and radiological analyses of maltracking and on loss of patellar tracking. There are five types of patellar instability and maltracking. The rare type 1 is a simple (traumatic) patellar dislocation without maltracking and instability with a low risk of redislocation. Type 2 has a high risk of redislocation after primary dislocation; there is no maltracking. Here, a stabilising operation (in most cases MPFL reconstruction) is indicated and sufficient. Type 3 shows both instability and maltracking. Maltracking is mainly caused by: (a) soft tissue contracture, (b) patella alta, (c) pathological tibial tuberosity-trochlea groove distance, (d) valgus deviations and (e) torsional deformities. Stabilisation by means of isolated MPFL reconstruction is not sufficient in these types and additional osseous corrective surgeries are required to achieve physiological patellar tracking and to prevent redislocation. Type 4 features a highly unstable "floating patella" with complete loss of tracking caused by severe trochlear dysplasia. Therapy of choice is trochleoplasty, and if necessary combined with bony and soft-tissue procedures. Type 5 shows a patellar maltracking without instability. Maltracking can only be fixed by means of corrective osteotomy. The classification is referenced to current literature and each type is introduced by a case example. The resulting treatment consequence is also presented.
    Article · Dec 2015
    • "This study focused on patients with severe varus OA with an average FTA of 183.7°, whereas the cohort studies mainly included subjects with mild knee malalignment. CT has great importance in the analysis of the patellofemoral joint, and patellar kinematics plays a role in the initiation and progression of patellofemoral OA [23]. The relationship between tibial torsion and medial OA was previously analysed using CT [31]; however, the effect of varus malalignment on patellofemoral OA is unclear. "
    [Show abstract] [Hide abstract] ABSTRACT: Purpose To evaluate the relationship between patellofemoral osteoarthritis (OA) and varus OA of the knee with a focus on the location of joint space narrowing. Methods Eighty-five patients scheduled to undergo total knee arthroplasty caused by varus OA were enrolled in this study. The relationship between patellofemoral OA and varus knee malalignment was elucidated. To determine the alignment of the patellofemoral joint in varus knees, patellar tilt, and the tibial tuberosity–trochlear groove (TT–TG) distance were measured, and patellofemoral OA was classified using computed tomography. Results The femorotibial angles in patients with stage II–IV patellofemoral OA were significantly larger than those in patients with stage I patellofemoral OA, and the patellar tilt in patients with stage II–IV patellofemoral OA and the TT–TG distance in patients with stage IV patellofemoral OA were significantly larger than those in patients with stage I patellofemoral OA. The TT–TG distance was strongly correlated with patellar tilt (R 2 = 0.41, P < 0.001). Patellofemoral joint space narrowing was mainly noted at the lateral facet, and it was found on both sides as patellofemoral OA worsened. Conclusion Varus knee malalignment was induced by patellofemoral OA, especially at the lateral facet. Patellar tilt and the TT–TG distance are considered critical factors for the severity of patellofemoral OA. Understanding the critical factors for patellofemoral OA in varus knees such as the TT–TG distance and patellar will facilitate the prevention of patellofemoral OA using procedures such as high tibial osteotomy and total knee arthroplasty to correct knee malalignment. Level of evidence Retrospective cohort study, Level III.
    Full-text · Article · Oct 2014
    • "Only 2D patellar kinematics, including patellar flexion angles and translations relative to the femur and tibia, were analysed in this study. However, several studies have shown abnormal sagittal plane kinematics in pathological knees [3, 5, 8, 21] and knees replaced by total knee arthroplasty [6, 7, 9, 10]. Tyler et al. [8] demonstrated that patients with patellar tendinitis have abnormal patellar tilt in the sagittal plane. "
    [Show abstract] [Hide abstract] ABSTRACT: Purpose: Lateral radiographic views can be easily taken and have reveal considerable information about the patella. The purpose of this study was to obtain sagittal plane patellar kinematics data through the entire range of knee flexion under weight-bearing conditions. Methods: Patellar flexion angles relative to the femur and tibia and anterior-posterior and proximal-distal translations of the patella relative to the femur and tibia were measured from 0 to 165° knee flexion in nine healthy knees using dynamic radiographic images. Results: The patella flexed relative to the femur and tibia by two thirds times and one third times the knee flexion angle, respectively. The patella translated in an arc relative to the femur and tibia as the knee flexed. In early flexion, the superior and centroid points translated anteriorly and then the patella translated posteriorly relative to the femur. All three points of the patella translated posteriorly relative to the tibia during a full range of flexion. An average of four and three millimetres proximal patellar translation relative to the tibia was demonstrated from 0 to 20° and 140 to 160° knee flexion, respectively. Conclusions: Physiological sagittal plane patellar kinematics, including patellar flexion angles and translations relative to the femur and tibia, showed generally similar patterns for each subject. Measurements of dynamic radiographic images under weight-bearing activities may enhance the opportunity to identify patellar pathological conditions.
    Full-text · Article · Jun 2013
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