Intra-observer and inter-observer reproducibility for agreement on osteophytes ranged between 0. Knee angles were measured by a blinded observer from standing anterior-posterior radiographs using the software program Osiris, as previously described [ 13 ]. Lines were drawn through the middle of the femoral shaft and through the middle of the tibial shaft.
The angle subtended at the point at which these two lines met in the centre of the tibial spines, and was recently validated by Hinman et al [ 13 ] as an alternative to the mechanical axis on full-leg radiographs. Although these degrees of varus and valgus are not clinically observed, a continuous range was used to avoid defining varus and valgus from an arbitrarily chosen midline value.
Intra-observer reliability expressed as ICC was 0. Cartilage volume and bone area was initially assessed for normality i. Confounders including age, weight and gender were adjusted for in the regression models. We have also adjusted analyses for static knee angle, in an attempt to control for any influence of knee malalignment.
Since cartilage volume is a known determinant of cartilage defects, defect analyses have subsequently been adjusted for cartilage volume. Likewise, metaphyseal bone area is a known determinant of cartilage volume, and as such, has been adjusted for in the appropriate analyses. Finally, all analyses were adjusted for the presence of MRI determined osteophytes based on previous work [ 1 ].
A P value of less than 0. All analyses were performed using the SPSS statistical package standard version Subject characteristics are shown in Table 1. The average height was The association between height measurements and knee joint structures are shown in Table 2.
That is, medial cartilage volume was increased by 27 mm 3 for every 1 cm increase in knee height, while lateral cartilage volume was increased by 42 mm 3 for every 1cm increase in knee height. In relative terms, for the medial compartment, this data demonstrated a 2. Although knee height was not associated with the risk of cartilage defects, knee height as a percentage of body height was associated with a reduced risk of the presence of medial tibial cartilage defects Odds ratio 0.
In asymptomatic community-based adults, we have demonstrated that increased anthropometric height measures are associated with increased tibial bone area, while knee height as a percentage of body height is associated with a reduced risk of medial tibial cartilage defects.
We have also found that knee height is associated with knee cartilage volume. The associations between increased anthropometric measures and increased bone area may simply reflect inherently larger bony structures. In the only previous study to have examined knee height, radiographic knee OA was associated with increased knee height among Beijing residents aged 60 years or older [ 1 ]. According to the Kellgren-Lawrence grading system, the diagnosis of radiographic OA is heavily reliant on the presence of osteophytes to classify disease.
The role of osteophytes in disease pathogenesis remains unclear, but much of the previous study's association between knee height and radiographic OA [ 1 ] may have been mediated by the presence of osteophytes. To further explore this concept, we found that knee height tended to be significantly associated with an increased risk for the presence of MRI osteophytes OR 1. MRI has been shown to be more sensitive than the joint radiograph at determining the presence of osteophytes [ 12 ].
Furthermore, we demonstrated that increased knee height is associated with increased tibial bone size, which supports knee height being inherently linked to bone morphology and may not necessarily be detrimental to other structures, such as cartilage. This leads to the quandary of determining whether increased knee height is to the detriment of the knee joint. In this study, we substantiate Hunter et al. Nonetheless, despite the deleterious association with the knee osteophyte, we have demonstrated that an increased knee height is associated with increased knee cartilage volume, although this relationship did not persist when knee height as a percentage of body height was examined.
This indicates that although knee height is associated with cartilage volume, the relationship is attenuated when the overall stature of an individual is accounted for. In contrast, knee height as a percentage of body height but not isolated knee height was associated with a reduced risk of medial tibial, but not lateral cartilage defects.
Why isolated knee height is associated with cartilage volume, and knee height as a percentage of body height is associated with reduced medial cartilage defects, but not vice versa, is unclear. However, the direction of these results is consistent and infer that increased knee height either isolated, or relative to total body height is associated with beneficial cartilaginous properties increased cartilage volume and reduced cartilage defects at the knee, suggesting a protective biological effect.
Moreover, the medial compartment specific association between knee height as a percentage of body height and cartilage defects further substantiates an underlying biomechanical mechanism, since knee joint loads are predominantly directed medially [ 15 ]. Cartilage defects are surface lesions which, independent of cartilage volume, predict cartilage loss and pain in both people with and without knee OA [ 16 — 21 ]. Why increased joint load, which is speculated to result from an increase in knee height, either alone or as a percentage of body height, benefits the cartilage of asymptomatic people is unclear.
It may be that healthy articular cartilage relies upon a certain degree of mechanical stimulation. In childhood, cartilage accrual is greater in physically active children [ 22 ], while in adults, forced immobility results in a rapid decline in knee cartilage [ 23 , 24 ]. Mechanical stimulation may therefore be imperative in maintaining cartilage health, although mechanocellular mechanisms may be easily perturbed when disease processes are activated by other means e.
There are a number of other factors that may also account for the differences between the results of our MRI study and the previous radiographic study. In contrast to our population which was Caucasian, the previous study examined Beijing residents. The Chinese have been demonstrated to have more valgus alignment of the distal femur than Caucasians [ 25 ]. Biomechanically, changes in varus-valgus alignment of the lower-limb can ameliorate the external knee adductor moment, which is the major determinant of joint load distribution at the knee [ 15 ].
In contrast to the previous study, we have adjusted for knee alignment. Moreover, we have examined a cohort of people without established knee OA. The disease status of a joint health may be a key determinant of how the chondrocyte responds to external loads.
Similarly, articular structures may respond differently to the same stimuli over the life-span. Whereas the previous study of Beijing residents examined people aged 60 or over [ 1 ], we have examined a younger population with only 2.
In addition, we also examined knee height as a proportion of total body height, which may explain further differences in the findings. This study has several limitations. Although we excluded people with a diagnosed arthropathy, we have not adjusted for the possibility of radiographic OA, despite adjusting for osteophytes. Measure Waist Size. Measure waist Size. Measure mid thigh circumference. Elbow Sleeve Size Chart. Measure Largest Part of Forearm. Measure Chest Circumference. Measure circumference at wrist.
Measure palm at base of fingers. Measure circumference at largest part of the calf. Ankle Support Size Chart. Size differences and deformity need to be taken into account when the patella is prepared for resurfacing.
It is recommended that the bony resection should be no greater than one third of the maximum patellar thickness to avoid alteration of normal bony structure. Key words: patella, total knee arthroplasty, anatomy.
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