RESEARCH REPORT PLATFORM PRESENTATION

KNEE JOINT ROTATION IN VIVO MEASUREMENTS – DEVELOPMENT OF AN EXTERNAL CLINICAL DEVICE AND CLINICAL STUDIES. Almquist P¹, Fridén T², Zätterström R³, Ekdahl C¹; ¹Department of Health Sciences, Division of Physiotherapy, Lund University, Lund, Sweden. ²Department of Orthopedics, Lund University, Lund, Sweden. ³Department of Physical Medicine, Lund University Hospital, Lund, Sweden

PURPOSE: Knee joint rotation is important for most weightbearing movements. During the stance phase of walking, the foot is fixed to the ground, this causes internal rotation of the tibia with ankle dorsiflexion and external tibial rotation with plantar flexion of the ankle. Excessive forces in the knee may tear ligamentous structures, resulting in defects in the envelope of passive motion, including rotatory motions. However, no clinical knee joint rotation measurement instrument, evaluated regarding validity and reliability exists, and tibio-femural rotation is hardly ever measured and evaluated in clinical works. The aim of this study was to develop a clinical external cevice for measuring knee joint rotation range of motion, as well as establish age and gender differences in a knee healthy reference population. RELEVANCE: The normal range of rotation of the knee in various healthy population in vivo is not known, age and gender differences are not established, and rotation is hardly ever estimated in clinical works. A device measuring knee joint rotation could be of great value as a complement to existing clinical tools and examination equipment. PARTICIPANTS: The knee healthy reference population was constituted of 120 persons, 60 females and 60 males, divided into four different age groups, 15-30, 31-45, 46-60 and>61 years old. The four age groups were divided to match different age related knee dysfunction problems in future studies. METHODS: The newly developed measurement instrument was used in the present study. It’s validity was evaluated by simultaneous measurements with Roentgen Stereometric Analysis on five male subjects. The intra- and intertester reliability were evaluated with 10 knee healthy subjects each. 120 knee healthy subjects, divided into genders and four different age groups, were used to represent a reference population, with the purpose to establish normal knee joint rotation and variations due to age and gender. The subjects were examined in 90, 60 and 30 degrees of knee flexion angle, with 6 and 9 Nm as well as the examiners apprehension of end-feel. ANALYSIS: Pearson’s coefficient of correlation, Five way analysis of variance, Anova and T-test were used for statistic analysis. RESULTS: The external device showed high validity (r2 0.83-0.90) and intra- and intertester reliability (r2 0.74-0.95). The females in the reference population showed significant larger (p < 0.001) range of knee joint rotation than the males. Knee joint rotation decreased significantly due to age in both genders (p < 0.001), and no differences between the right and left knees were found. CONCLUSIONS: The newly developed device was a valid and reliable measurement instrument. In the knee healthy reference population, the females showed significant larger range of rotation than the males, the knee joint rotation decreased significantly due to age in both genders and no differences between the right and left knees were found. IMPLICATIONS: Further knowledge about normal knee joint rotation and variations due to age and genders, which maybe could have an influence in different knee joint disorders. KEYWORDS: Knee, rotation, measurements. FUNDING ACKNOWLEDGEMENTS: This work was funded by County Council of Halland foundation, Sweden and Bertil Hemborgs foundation.

ETHICS COMMITTEE: The study was approved by the Ethics Committee of Lund University