Studies regarding postural sway are generally taken from patients with medial knee osteoarthritis. The relationship between postural sway and different knee alignments among healthy males has not yet acquired much attention in Japan. Therefore, the goal of the present study is to examine the relationship and provide the findings.
Method:
Subjects were 15 healthy males with no history of knee injury: 5 with normal knees (NK), 5 with genu valgum (GVL), and 5 with genu varum (GVR). Their postural sways were calibrated with a stabilometer (ANIMA Corp.) for 30-sec. The device observed the trajectory length of sway for the X (front-back) and the Y (left-right) directions with OE (opened eyes) and CE (closed eyes) conditions (2-direction × 2-condition × 3-knee-alignment), and averaged these values for each group. One-way Tukey’s method was used for comparing each group’s average scores (p< .05).
Analysis/Results:
The X trajectory length with OE was 38.0±4.1 cm for NK, 34.9±5.4 cm for GVL, and 25.8±5.9 cm for GVR. The X trajectory length with CE was 47.1±8.5 cm for NK, 53.9±5.4 cm for GVL, and 29.4±6.1 cm for GVR. The GVR group demonstrated significantly lower average scores (more stability) than the other two groups with both OE and CE conditions. The Y trajectory length with OE was 26.1±5.3 cm for NK, 31.0±7.4 cm for GVL, and 18.9±3.1 cm for GVR. The Y trajectory length with CE was 33.3±5.6 cm for NK, 50.5±6.6 cm for GVL, and 27.0±3.4 cm for GVR. With the OE condition, the GVR group received lower scores than the GVL group. Moreover, both the GVR and NK groups demonstrated lower scores than the GVL group in the CE condition.
Conclusions:
In summary, the results suggest that out of the three knee alignment criterion, GVR might be the most stable alignment type. However, future studies should employ larger sample sizes for more statistical power and should take some possible factors into consideration which can better explain this result. It has been reported that knee alignment is determined by around 15-year old, and the high proportion of GVR in Japanese people may be an adaptation for stabilizing a standing posture for a long period of time. For practical implications, unique patterns of postural sway by knee alignment possibly hold inherent risks of rollover in motion. Thus, coaches/trainers may need to develop specific training procedures such as balance-training based on the characteristics of athletes/clients’ knee alignment.
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