Published in:
01-10-2003 | Musculoskeletal Soft Tissue Conditioning
The influence of alignment on the musculo-skeletal loading conditions at the knee
Published in: Langenbeck's Archives of Surgery | Issue 5/2003
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Background and aim
High tibial osteotomies attempt to recreate physiologically normal joint loading. Previous studies have discussed the influence of mal-alignment on the distribution of static loads to the medial and lateral compartments of the knee. The aim of this study was to determine the influence of mal-alignment on the tibio-femoral loading conditions during dynamic activities.
Material and methods
Using a musculo-skeletal model of the lower limb, which had been previously validated with in vivo data, in this study we modified the alignment of the knee in four patients, from a normal position to the extremes of 8° valgus and 10° varus mal-alignment. The resulting tibio-femoral joint contact forces were examined while patients were walking and stair climbing.
Results
Varying the mal-alignment resulted in a highly individual response in joint loads. Deviations from the normal alignment produced an increase in loading, with valgus generating a more rapid increase in loading than a varus deformity of the same amount. Varus deformities of 10° resulted in increases in peak contact force from an average of 3.3-times bodyweight (BW) up to a peak of 7.4 BW (+45% to +114%) while patients were walking, whilst increases of 15% up to 35% were determined for stair climbing. Increases of up to 140% were calculated at 8° valgus during walking and up to 53% for stair climbing.
Conclusion
This study demonstrated a clear dependence of the individual joint loads on axial knee alignment. Based on the sensitivity of joint loading to valgus mal-alignment, more than 3° of over-correction of a varus deformity to valgus should be carefully reconsidered.