Objective. To compare the knee joint loading patterns in individuals with differing radiographic grades of knee osteoarthritis (OA) for characterization of the mechanical implications of different structural states, and to compare the knee adduction angular impulse, a measure of gait complementary to the commonly used peak knee adduction moment.Methods. Asymptomatic subjects (those without knee OA) having a Kellgren/Lawrence (K/L) radiographic severity grade of 0 or 1 (n ‫؍‬ 28) and subjects with symptomatic knee OA having K/L grades of 2 (n ‫؍‬ 66) or 3 (n ‫؍‬ 23) were recruited. Gait analysis was used to calculate the peak external knee adduction moment and the external knee adduction angular impulse for the whole stance and for the 4 subdivisions of stance.Results. Both the peak knee adduction moment and the knee adduction angular impulse increased with K/L radiographic grade (P < 0.05). However, only the knee adduction angular impulse differed between subjects with moderate (grade 3) and those with mild (grade 2) radiographic knee OA (P < 0.05).Conclusion. The differences between mild and moderate symptomatic radiographic knee OA are not only structural but also functional, based on the magnitude of load in the medial knee joint. Moreover, knee adduction angular impulse provides additional information beyond that available from the peak knee adduction moment, and may therefore be an important gait parameter to include in OA research. These findings are important for our understanding of the pathophysiologic mechanisms of OA.The peak external joint moments determined by gait analysis are surrogate markers of the effects of contact load on an individual's joints. In particular, in the knee, the external adduction moment is the primary predictor of load distribution across the tibial plateau (1) and is a main determinant of clinical outcomes following surgical intervention to correct varus deformity (2). Individuals with symptomatic radiographic knee osteoarthritis (OA) have higher-than-normal peak external knee adduction moments during walking (3-8).The peak external knee adduction moment has been implicated in progression of radiographic OA (9) and has been identified as a marker of disease severity (8,10), when individuals with OA radiographic severity grades Յ2 are compared with those with grades Ն3, using the Kellgren and Lawrence (K/L) scale (11). In addition, when the first and second peak external knee adduction moments, occurring during midstance and terminal stance, respectively, were compared in healthy controls and in individuals with less or more severe OA, the first peak was higher than normal regardless of disease severity, whereas the second peak was higher than normal only in those with more severe OA (8).As a measure of knee load, the peak external knee adduction moment reflects only a single time point during stance and is independent of the duration of the stance phase of gait. Because individuals with OA ambulate at slower speeds (3) and exhibit a prolonged stance phase as compared with hea...

Objective. The relationship between knee pain and radiographic evidence of knee osteoarthritis (OA) is notoriously imperfect. In particular, conditions that distinguish individuals with symptoms from those with comparable radiographic involvement who remain asymptomatic are unclear. We investigated dynamic loading across the knee in individuals with mild radiographic OA who were distinguished by the presence or absence of knee pain. Methods. Subjects were recruited into 3 groups: symptomatic with a Kellgren/Lawrence (K/L) grade of 2 (n ‫؍‬ 52), asymptomatic with a K/L grade of 2 (n ‫؍‬ 19), and asymptomatic with a K/L grade of 0 or 1 (n ‫؍‬ 37), the latter representing a normal comparator group. Dynamic knee loading was assessed with gait analysis, and both the peak external knee adduction moment and the knee adduction angular impulse were determined. Results. Peak knee adduction moment and knee adduction angular impulse were 19% and 30% higher, respectively, in symptomatic K/L grade 2 individuals than in asymptomatic individuals with the same radiographic grade (P < 0.05). Conversely, the asymptomatic K/L grade 2 group did not differ from the K/L grade 0 -1 normal comparator group (P ‫؍‬ 1.00). Conclusion. Among individuals with mild radiographic knee OA (K/L grade 2), those who are symptomatic have significantly higher medial compartment loads than those who are asymptomatic, whereas those who are asymptomatic do not differ from normal controls (asymptomatic K/L grade 0 or 1). These findings suggest a biomechanical component to the distinction between asymptomatic and symptomatic radiographic OA, which may be pathophysiologically important.

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Objective The contralateral knee of those with unilateral endstage hip OA is known to be at greater risk for endstage knee OA compared to the ipsilateral, same side knee. Likewise, in endstage hip OA, this contralateral knee is known to have increased dynamic joint loads compared to the ipsilateral knee. Here, we study a population with unilateral hip OA, who are asymptomatic at the knees, for early asymmetries in knee loading. Methods Data from 62 subjects with unilateral hip OA were evaluated. Subjects underwent gait analyses for evaluation of dynamic knee loads as well as dual energy X-ray absorptiometry for evaluation of bone mineral density (BMD) at both knees. Differences between knees were compared. Results Peak dynamic knee loads were significantly higher at the contralateral knee compared to the ipsilateral knee (2.46±0.71 vs 2.23±0.81 %BW*ht, p=0.029). Similarly, medial compartment tibial BMD was significantly higher at the contralateral knee compared to the ipsilateral knee (0.897±0.208 vs 0.854±0.206 gm/c2, p=0.033). Interestingly, there was a direct correlation between contralteral:ipsilateral dynamic knee load and contralateral:ipsilateral medial compartment tibial BMD (Spearman’s rho= 0.287, p=0.036). Conclusions This study demonstrates that at the contralateral knees of patients with unilateral hip OA, which are at higher risk of developing progressive symptomatic OA compared to the ipsilateral knees, loading and structural asymmetries appear early in the disease course, while the knees are still asymptomatic. These early biomechanical asymmetries may have corresponding long term consequences, providing further support for the potential role of loading in OA onset and progression.

Objective. Biomechanical interventions for knee osteoarthritis (OA) aim to improve pain and retard disease progression by decreasing knee loading. This study was undertaken to evaluate the effects of 6 months of use of flat, flexible footwear (the mobility shoe) on knee loading in OA.Methods. Subjects with knee OA underwent baseline gait analyses under conditions of walking in their own shoes, walking in mobility shoes, and walking barefoot. Thereafter, subjects wore the mobility shoes at least 6 hours per day for 6 days per week. Gait evaluations were repeated at 6, 12, and 24 weeks. An intentto-treat analysis was performed to assess the longitudinal effects on knee loading with the shoe intervention.Results. Compared to knee loading at baseline with the participants' own shoes, there was an 18% reduction in the knee adduction moment (KAM) by 24 weeks with the mobility shoes (P < 0.001) and no significant differences in the KAM by 24 weeks between mobility shoe and barefoot walking (P ‫؍‬ 0.192). Over the 6 months of followup, participants also experienced an 11% reduction in the KAM when walking in their own shoes (P ‫؍‬ 0.002) and a 10% reduction in the KAM when walking barefoot (P ‫؍‬ 0.002 for the whole followup), as compared to these values at baseline under the same conditions.Conclusion. This study suggests that use of flat, flexible footwear results in significant reductions in knee loading in subjects with OA. By 24 weeks, there is evidence of a gait adaptation with sustained load reduction even when the mobility shoes are removed, suggesting that footwear may serve as a biomechanical training device to achieve beneficial alterations in gait mechanics for knee OA.

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Review of anatomy coupled with the teaching of clinical procedures results in an anatomical review superior to that of traditional methods, enhances knowledge of clinical procedures, and heightens students' awareness of the relationships between basic science and clinical practice.

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