我々が日常, 臨床で扱う膝関節痛について, 長期間経過している高齢者を対象に, 下肢のアライメント, 膝蓋骨の可動性と膝関節痛の関係を考えてみた。下肢のアライメントの計測を3種類の方法で, すなわち, 内反膝, 外反膝の程度をF-T角, 膝蓋骨の前額面での偏位をQ角, 膝の伸展制限をE角で計測した。膝蓋骨の可動性は上下, 左右方向を調べた。更に, 膝関節痛の好発部位を6箇所とし, うち2か所を選んで疼痛部位とした。結果は, F-T角が痛みの持続性に影響を与え, 痛みの部位は主に内膝眼と曲泉に集約される傾向があった。Q角とE角の変化は痛みの長期化に関与しなかった。膝蓋骨の可動性の低下も痛みの発症に影響を与えていると推測できた。

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The aim of this study was to clarify the relationship between the changes of alignment of the lower extremity in the coronal and horizontal planes at the level of the knee, and the imbalance of muscle strength in primary osteoarthritis (OA) of the knee.
Sixty patients of primary OA of the knee were graded according to the CIOMS radiographic system. Femorotibial angle (FTA) and joint space angle (JA) were measured with X-rays of the whole limb in standard position. The rotational deformities were assessed by computerized axial tomography. The rotational change of the tibia against the femur on quadriceps contraction was also measured. Muscle activities were estimated from electromyographic measurement of muscle contraction during walking using surface electrodes.
In the early stage of OA, a decrease of external rotation of the tibia without any change in FTA and JA was demonstrated, and it was well correlated with the decreased activity of the vastus medialis muscle. Relative increase in the activities of the lateral supporting muscles of the knee was also observed with the progression of OA, and this finding could be understood to indicate the role of the lateral supporting muscles in withstanding varus deformity of the knee. But in advanced OA, it was estimated that this mechanism was not sufficient to stop the progression of the varus deformity.
From these results, we concluded that disturbance of the screw-home movement due to the relative decrease of activity of the vastus medialis muscle should be considered one of the most important factors in the onset of OA of the knee.

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