Correlation between patellar stability and keen Lysholm scoring in adult with Kaschin-Beck disease: a multiple linear regression analysis

Abstract

Objective To study the correlation between patellar stability and keen clinical manifestation in adults with Kaschin-Beck disease (KBD). Methods Through a cross-sectional study in September 2016, one hundred and forty-three adult patients with KBD were asked to accept a digital radiographic X-ray (DR) which included positive and lateral slices of knee joint and axis slice of patellar. Meanwhile, every patient must undergo a Lysholm function evaluation for knee joint and morphological measurement on the DR film which included Insall index, lateral patellofemoral angle, sulcus angle, congruence angle, lateral migrating ratio of patella, and patellofemoral index. Then, the regression equation was built and the correlation analysis was made with multiple linear regression test. Results One hundred and forty-three patients' average scores of Insall index, lateral patellofemoral angle, sulcus angle, congruence angle, lateral migrating ratio of patella, patellofemoral index and Lysholm score were 1.10 ± 0.17, (14.49 ± 1.47)°, (138.08 ± 3.86)°, (11.55 ± 2.17)°, (1.34 ± 0.13)%, 1.18 ± 0.10, and (62.96 ± 6.11) scores. By multiple linear regression test, Insall index (X1), congruence angle (X4), lateral migrating ratio of patella (X5), and patellofemoral index (X6) were selected to enter into the equation; while, lateral patellofemoral angle and sulcus angle were rejected. The multiple linear regression equation was as follows: Y= 17.529+ 15.232X5+ 0.950X4+ 15.957X6-4.224X1. The adjusted determination coefficient (R2) of the equation was 0.559. Those indexes which were selected to enter into the equation were ranked from big to small based on the impact on Lysholm as follow: congruence angle, lateral migrating ratio of patella, patellofemoral index, and Insall index. Among them, Lysholm score had a negative correlation with Insall index. Through variance analysis, F valve was 46.642, and P < 0.05, which meant the fitted equation had statistical significance. Conclusion There is significant correlation between the patellar stability and knee Lysholm scoring in adult with KBD, which is reflected with the following parameters from big to small in turn: patellofemoral index, lateral migrating ratio of patella, congruence angle and Insall index. Key words: Kaschin-Beck disease; Patella; Patellofemoral joint; Lysholm score; Regression analysis