A single measure of patellar kinematics is an inadequate surrogate marker for patterns of three-dimensional kinematics in healthy knees

Is There a Biomechanical Link Between Patellofemoral Pain and Osteoarthritis? A Narrative Review

The patellofemoral (PF) joint is the knee compartment most commonly affected by osteoarthritis (OA). Even mild PF OA is associated with considerable pain and functional limitations. Despite its prevalence and impact, little is understood of the etiology or structural and functional features of PF OA. The clinical symptoms of PF OA, such as anterior knee pain during stair ambulation and squatting, share many similarities with PF pain in adolescents and young adults. PF joint OA is most commonly diagnosed in people aged >40 years, many of whom report a history of PF pain. As such, there is growing evidence that PF pain and PF OA form a continuum of disease. This review explores the possible relationship between the presence of PF pain and the development of PF OA. We review the evidence for altered neuromotor control and biomechanical factors that may be associated with altered PF loading in people with PF pain and PF OA. In doing so, we highlight similarities and differences that may evolve along the continuum. By improving our understanding of the neuromotor and biomechanical links between PF pain and PF OA, we may highlight potential targets for new rehabilitation strategies.

Three-dimensional motion analysis of the patellar component in total knee arthroplasty by the image matching method using image correlations

In total knee arthroplasty (TKA), the patella is significantly associated with range of motion and gait performance. Currently, no highly accurate methods are available that can measure the 3D in vivo behavior of the TKA patellar component, as the component is made of x-ray-permeable ultra-high molecular weight polyethylene. Previously, we developed a computer simulation that matches CT scan and unidirectional radiographic images using image correlations, and applied it to kinematic studies of natural and TKA knees. The examination of the measurement accuracy for the patellar bone of a fresh-frozen pig knee joint yielded a root mean square error of 0.2 mm in translation and 0.2° in rotation. In this study, we recruited four patients who had a TKA and investigated 3D movements of the patellar component during squatting. We could visualize the patellar component using the position of the holes drilled for the component peg, and estimated and visualized the contact points between the patellar and femoral components. The principles and the utility of the simulation method are reported. This analytical method is useful for evaluating the pathologies and post-surgical conditions of the knee and other joints.

Predicting three-dimensional patellofemoral kinematics from static imaging-based alignment measures

Patellofemoral pain syndrome causes significant discomfort and disability among much of the general population. Despite recent breakthroughs in dynamic three-dimensional imaging technologies to assess pathological patellofemoral motion, such tools remain costly for clinical diagnostics applications. Thus, this study investigated whether three-dimensional patellofemoral kinematics could be predicted from routine two-dimensional static measures of patellofemoral joint alignment quantified from magnetic resonance imaging (MRI) data acquired in full knee extension. Twenty-six volunteers clinically diagnosed with patellofemoral pain (19 F/7 M, 25.9 ± 11.1 years) and 26 control subjects (19 F/7 M, 25.3 ± 7.7 years) were included in this IRB-approved study. Static three-dimensional sagittal T1-weighted gradient recall echo and dynamic MRI scans were acquired. For the dynamic image acquisition, subjects cyclically flexed and extended their knee (at 30 cycles/min) while a full cine-phase contrast MRI set (24 time frames of anatomic images and x-, y-, and z-velocity images) was acquired. From these data, static measures of patellofemoral alignment and three-dimensional patellofemoral kinematics were derived. Single and multiple regressions between static and kinematic variables were evaluated. Although shown reliable, the static MRI measures could only partially predict patellofemoral kinematics, with r(2) -values ranging from 16% to 77%. This makes it imperitave that the current precise, accurate, 3D, dynamic imaging techniques be translated into clinical tools.

Patellofemoral disorders: role of computed tomography and magnetic resonance imaging in defining abnormal rotational lower limb alignment

Background:

The contribution of lower limb rotational malalignment to patellofemoral pain and instability has been well recognized. The purpose of the present study is to review the role of computed tomography (CT) and magnetic resonance imaging (MRI) in assessment of abnormal rotational alignment of lower limb.

Evidence Acquisition:

An analysis of all available literature in the English language through 2010 was performed to provide data on a comparison between MRI and CT—specifically, the techniques and normative values used to determine abnormal lower limb alignment.

Results:

CT and MRI are highly accurate in defining abnormal alignment of the lower limb. Determination of axis of femoral anteversion in proximal femur has been the subject of debate in the literature. The determination of distal femoral condylar axis, proximal tibial axis and distal tibial axis are less controversial.

Conclusions:

CT and MRI are both used for assessing the rotational abnormalities of the femur and tibia during evaluation for patellofemoral disorders. MRI has an advantage over CT because femoral anteversion measurements are more accurate and ionizing radiation is avoided. A standardized protocol defining the level and axes for measurement of femoral and tibial alignment indices should be used to maintain consistency in measurements.

Joint mechanics measurement using magnetic resonance imaging

Magnetic resonance imaging-based methods for measuring the mechanics of human joints have been successfully applied to quantitatively evaluate biomechanics in a wide variety of joints, pathologies, and interventions. The objective of this review was to provide a detailed overview of methods in the literature for measuring joint kinematics, meniscal and ligament movement, and cartilage strain using MRI.