No abstract

Patellar tracking is defined as the motion of the patella relative to the femur or femoral groove on knee flexion and extension. Abnormalities of tracking (maltracking) are thought to relate to many disorders of the patellofemoral joint and may be defined easily or may be extremely difficult to observe. Accurate measurement of patellar tracking, and definition of normal tracking, have not been achieved yet in experimental conditions or in clinical conditions. Such information would be valuable in the diagnosis and treatment of patellofemoral disorders. In the current report, the literature is reviewed critically with an emphasis on methodology and results. The reporting of patellar tracking is affected significantly by basic definitions of coordinate systems and reference points. The method of muscle loading, range, and direction of knee motion, use of static or dynamic measurement techniques, and tibial rotation also will affect the results obtained. The accuracy of the equipment used is important as differences in tracking may be small. Comparison between existing studies is difficult because of differences in methodology. There is general agreement that the patella translates medially in early knee flexion and then translates laterally. Regarding patellar tilt, results are less consistent, especially in vivo and the results for patellar rotation are highly variable.

Patellofemoral motion is significant clinically, yet in the literature many different methods and terminologies are used, thus making comparison between papers difficult. The aim of this study was to review and explain the different methods used for the description of patellofemoral joint motion, compare these methods by experimentation, and propose a standardised method. We found three main methods for describing patellar motion: motion of the patella about femoral body fixed axes, about patellar body fixed axes, or a combination of these. Description about femoral body fixed axes does not make sense clinically. Description about patellar body fixed axes is straightforward, yet the definition of these axes is prone to error due to the lack of anatomical landmarks. The combination method makes most sense clinically and uses more easily found anatomical landmarks. Patellar flexion varied by up to 26% when describing the motion about different axes. Tilt and shift were highly sensitive to the choices of coordinate systems and the axes of motion. The pattern of rotation was consistent between all methods, however, differences between the methods increased with patellar flexion. We propose the description of patello-femoral motion in terms of shift (along a femoral medial-lateral axis), tilt (about the patellar long axis), rotation (about a floating patellar anterior-posterior axis) and flexion (about the femoral medial-lateral axis).

Photography was used to study the geometry of the cartilaginous and osseous contours of the distal femur and the orientation of the trochlear groove in 9 fresh-frozen and 24 embalmed knees. The sulcus angle (146.1 degrees +/-5.5 degrees ) decreased from 0 degrees to 50 degrees of femoral flexion then increased afterwards. The maximum slope of the lateral femoral condyle (20.2 degrees +/-5.2 degrees ) also decreased with flexion. Both the sulcus angle ( p=0.0007) and maximum slope ( p=0.0001) were larger at 0 degrees than they were for 60 degrees cartilaginous surfaces. The lateral femoral condylar height decreased, whilst the medial femoral condylar height increased as the flexion increased. The femoral groove was midway between the two femoral epicondyles (49.5+/-3.9%), but deviated laterally as the flexion angle increased. The groove axis deviated distally and laterally from the femoral anatomical axis for both cartilaginous and bony surfaces, and the angle between the groove and anatomical axes was similar for both cartilaginous (19.1 degrees ) and osseous (16.8 degrees ) surfaces. Articular cartilage is not well represented on radiography yet it had a significant effect on the distal femoral geometry, and should be taken into account when evaluating the patellofemoral joint.

BackgroundA high percentage of young children present with flatfeet. Although the percentage of those with flatfeet declines with age, about 15% of the population maintains a flat arch. A reduction in longitudinal arch height usually combines with excessive subtalar joint pronation and may be related to other musculoskeletal problems of the lower extremity kinetic chain. The purpose of this study is to describe and compare the lower extremity kinematics between children with normal arches and those with flexible flatfeet, with the intent of providing practical information for decision making when treating children with flexible flatfeet.MethodsTwenty children with flexible flatfeet (years age mean (SD), 9.7 (0.9) years) and 10 children with normal arches (yeas age mean (SD), 9.6 (1.2) years) were included. Kinematic data (maximum and minimum angles, and movement range, velocity, and excursion) of the hip, knee and rearfoot were collected during walking using Liberty Electromagnetic Tracking System. Kinematic variables were compared between the normal arches and flexible flatfeet groups using repeated measures mixed effects ANOVA.ResultsMovement patterns at the hip, knee and ankle joints were similar between children with flexible flatfeet and with normal arches. The results of ANOVA showed no significant main effect or interaction in any of the kinematic variables (P ≥ 0.05).ConclusionsThis study identified no kinematic adaptation during walking in children with flexible flatfoot. We suggested that future research should take the influence of the mid-foot and forefoot into consideration when examining lower extremity kinematics in children with flexible flatfoot.