2017 ISAKOS Biennial Congress IFOSMA ePoster #5061

 

Clinical Study of Age-related Changes of Posterior Tibial Slope and Its Roles in Cruciate Ligament Injury

Yinghua Sun, PhD, Weifang, Shandong CHINA
Lianxu Chen, Beijing, Beijing CHINA

Yidu Central Hospital, Weifang Medical University, weifang, shandong, china

FDA Status Not Applicable

Summary

The posterior inclination of the tibial plateau relative to the longitudinal axis of the bone, known as the posterior tibial slope (PTS), is usually gained by the angle measurement between the tibial shaft anatomical axis vertical and the tibia platform posterior slope tangent. However, the difference in the published PTS value is significant. PTS, anterior cruciate ligament (ACL), and posterior cruciate ligament (PCL), having close relationship among themselves, are all important anatomical structures of knee. Many studies have reported that an increased PTS is a risk factor for noncontact ACL injury. However, some others thought that an increased PTS has no correlation with ACL injury. Furthermore, few studies about PTS and PCL injury are found at home and abroad today. After summarizing the previous studies, a conclusion is drawed that nearly all the previous researchers have ignored the impacts on the results by the possible age-related changes of PTS.

Abstract

Purpose

On the basis of the above background, the present study aims to determine whether there is: First, some changes of PTS value with advancing age. Second, some changes of the correlation relationship between PTS and ACL injury with advancing age. Third, some changes of the correlation relationship between PTS and PCL injury with advancing age.

Methods

Weight-bearing radiographs of lower limbs from Han Chinese inpatients taken between January 2011 and January 2014 were retrieved from the Shandong University Qilu Hospital archives. Data for 2618 lower limbs were included initially with lateral views being taken with both the tibia and femoral condyles overlapping with at least 20 cm of the tibial shaft and with the femur visible. A femoro-tibial angle (FTA) between 170° and 175° was required. A total of 1187 subjects were excluded: 329 cases for previous reparative surgery, 284 cases for femoral or tibial fracture, 228 cases for a congenital structural anomaly, 186 cases for developmental delay, and 160 cases for the presence of serious osteophytes. The final 1431 subjects were grouped into nine 10-year age intervals with ages ranging from 0–9 years to 80–89 years. PTS was gained by the angle measurement in the lateral radiograph between the vertical of tibial proximal anatomical axis and the tangent joining the highest anterior and posterior points of the platform. Every PTS value was measured twice by one researcher as well as by the other independently and blindly, and the mean value was as its final value. The repeatability and reproducibility of the PTS measurement method were evaluated, and all the data were analyzed in order to find the changes of PTS with advancing age. In all the 1431 subjects, 93 cases (including 55 male cases and 38 female cases) were gained for noncontact ACL injury, and 26 cases (including 18 male cases and 8 female cases) for PCL injury. The changes of correlation relationship between PTS and noncontact ACL injury were analyzed in activity crowd, i.e. 20–29, 30–39, 40–49, and 50–59-year-old groups. Furthermore, the changes of the correlation relationship between PTS and PCL injury were evaluated in 10–29, 30–49 and 50–69-year-old groups. Data normality was assessed using Shapiro-Wilk test (n ≦ 50) or Kolmogorov-Smirnov test (n > 50), and homogeneity of variance was assessed using Levene's Test. All normal quantitative data are expressed as mean ± standard deviation, and independent Student’s t-tests were used to identify statistically significant differences between the two different groups. Line graphs, scatter diagrams, curve fitting (regression equation: ), and linear fitting (regression equation: ) were used to identify the changes of PTS with advancing age. All analyses were conducted using SPSS version 19.0. P < 0.05 was considered to be statistically significant.

Results

The final 1431 subjects aged 0 to 89 years old were distributed into nine 10-year age intervals, then every age group was analyzed again according to gender and side. Firstly, analysis of PTS for each gender among the nine age groups: The PTS values differed significantly between males and females in the 0–9, 30–39, 40–49, 60–69, 70–79, and 80–89-year-old groups (P < 0.05). In the 0–9 and 30–39-year-old groups, the PTS in males (16.93°±2.94°, 11.11°±2.85°) was greater than that in females (14.34°±2.63°, 10.11°±2.81°), whereas in the 40–49, 60–69, 70–79, and 80–89-year-old groups, the PTS in men (9.53°±2.82°, 9.09°±2.92°, 9.99°±3.39°, 10.20°±3.42°) was lower than that in women (10.81°±3.13°, 11.14°±3.35°, 12.09°±3.84°, 12.39°±3.91°). However, there were no significant differences in the PTS between males (13.50°±3.27°, 11.26°±2.72°, 9.40°±3.07°) and females (12.63°±3.18°, 10.84°±2.53°, 10.30°±2.99°) in the 10–19, 20–29, and 50–59-year-old groups (P > 0.05). Secondly, analysis of left vs. right PTS among the nine age groups: In the 0–9, 10–19, 50–59, 60–69, and 80–89-year-old groups, the PTS of the left side (16.63°±2.75°, 13.77°±3.25°, 10.62°±3.06°, 11.20°±3.34°, 12.54°±4.16°) was greater than that of the right side (14.71°±3.11°, 12.53°±3.15°, 9.25°±2.85°, 9.45°±3.11°, 11.01°±3.50°) (P < 0.05). However, there were no significant differences between the left (11.32°±2.60°, 10.78°±2.86°, 10.58°±3.02°, 11.63°±3.58°) and right (10.70°±2.65°, 10.26°±2.85°, 9.83°±3.08°, 11.18°±4.10°) sides in the 20–29, 30–39, 40–49, and 70–79-year-old groups (P > 0.05). Thirdly, analysis of PTS in males among the nine age groups: For men, in the 0–9, 10–19, and 70–79-year-old groups, the PTS value of the left side (17.92°±2.50°, 14.21°±3.26°, 11.06°±3.42°) was greater than that of the right side (15.73°±3.04°, 12.75°±3.13°, 9.00°±3.11°) (P < 0.05). However, there were no significant differences between the left (11.45°±2.74°, 11.20°±3.13°, 9.71°±2.69°, 9.88°±3.35°, 9.30°±2.66°, 10.68°±3.59°) and right (10.96°±2.70°, 11.03°±2.59°, 9.26°±3.02°, 8.83°±2.65°, 8.81°±3.24°, 9.88°±3.36°) sides in the 20–29, 30–39, 40–49, 50–59, 60–69, and 80–89-year-old groups (P > 0.05). Forthly, analysis of PTS in females among the nine age groups: For females, in the 50–59 and 60–69-year-old groups, the PTS value of the left side (10.98°±2.86°, 12.52°±3.13°) was greater than that of the right side (9.46°±2.95°, 9.79°±3.01°) (P < 0.05). However, there were no significant differences between the PTS of the left (14.99°±2.14°, 13.05°±3.13°, 11.16°±2.44°, 10.51°±2.67°, 11.23°±3.11°, 11.86°±3.64°, 13.16°±4.20°) and right (13.75°±2.93°, 12.07°±3.22°, 10.49°±2.62°, 9.55°±2.93°, 10.24°±3.09°, 12.39°±4.10°, 11.60°±3.47°) sides in the 0–9, 10–19, 20–29, 30–39, 40–49, 70–79, and 80–89-year-old groups (P > 0.05). Fifthly, analysis of the change trend of PTS values: For male and female data combined, male samples only, and female samples only, the line graphs of mean PTS value, as well as the scatter diagrams and curve fitting of PTS value all showed a trend of first decreasing and then increasing with increasing age (P < 0.001). However, for male and female data combined, male samples only, and female samples only, matching the curve fitting models (P < 0.001), (P < 0.001), and (P < 0.001), the trough of the curve appeared in the 40–60 years old age of middle, rear and front respectively. Sixthly, analysis of the role of PTS in noncontact ACL injury: The high incidence of noncontact ACL injury was in 20–59 years old activity crowd. In the 20–29, 30–39, and 40–49-year-old groups, the PTS value was greater in injured knees (13.31°±1.63°, 12.67°±2.00°, 11.68°±2.67°) than in non-injured knees (10.80°±2.61°, 10.22°±2.83°, 10.01°±3.09°) (P < 0.05). However, in the 50–59-year-old group, there was no significant difference between injured knees (11.18°±2.82°) and non-injured knees (9.83°±3.04°) (P > 0.05). In activity crowd, i.e. the 20–29, 30–39, 40–49 and 50–59-year-old groups, for injured knees, as well as non-injured knees, the line graph of mean PTS value showed a change of decreasing with increasing age. Moreover, the mean PTS value of injured knees and non-injured knees both fitted a negative linear (P < 0.05), and matched the regression equation respectively , (P < 0.05), and , (P < 0.05). Seventhly, analysis of the role of PTS in PCL injury: In the 10–29, 30–49, and 50–49-year-old groups, there were no significant differences between PCL injured knees (10.99°±2.79°, 10.20°±3.19°, 11.57°±1.74°) and non-injured knees (12.10°±3.20°, 10.11°±2.97°, 10.09°±3.22°) (P > 0.05). Moreover, for total subjects in the three age groups, PCL injured knees (10.92°±2.60°) were also not different significantly from non-injured knees (10.77°±3.27°) (P > 0.05). There were all no significant differences between PCL injured knees (10.68°±2.83°, 11.46°±2.03°) and non-injured knees (10.83°±3.48°, 10.73°±3.11°) in both male and female patients (P > 0.05). Moreover, there were all no significant differences between male (10.68°±2.83°, 10.83°±3.48°) and female patients (11.46°±2.03°, 10.73°±3.11°) both in PCL injured knees and non-injured knees (P > 0.05).

Conclusion

First, the PTS value follows an overall trend of first decreasing and then increasing with advancing age. There is no significant difference between male and female in youth. However, after the age of youth, the PTS value changes little by little between male and female, with initially male being greater than female and finally female being greater than male. Moreover, the PTS value of left side is greater than that of right side in some age groups. Second, the relationship between PTS and noncontact ACL injury changes with aging. An increasing PTS is a risk factor for noncontact ACL injury in activity crowd. However, the role of the risk factor is being decreasing with advancing age. Third, the anatomical structure of PCL is strong, and PCL is mostly injuried by powerful external force. Therefore, PTS value is not enough to as the risk factor for PCL injury in all ages.