Summary

Derotational Tibial Osteotomy for Pathological External Tibial Torsion Correction in Females with Anterior Knee Pain Should be Infratuberositary

Abstract

BACKGROUND. Pathological external tibial torsion (ETT) has been recognized as one of the causes of anterior knee pain (AKP). Good results have been obtained after correcting tibial maltorsion by performing a derotational tibial osteotomy. However, it is not clear at what level the osteotomy should be performed.
PURPOSE. To perform a segmental analysis of tibial torsion in patients, with normal and increased ETT, suffering from AKP and to investigate a possible correlation between ETT and the position of the tibial tuberosity (TT).
METHODS. A study was conducted on 197 CT scans of the tibia from 101 women with AKP who were evaluated for femoral and/or tibial torsion. The patients were categorized into three groups: normal ETT (≤ 30º), moderate ETT (31º - 40º), and severe ETT (> 40º). ETT was measured both proximally and distally to the TT and the percentage of contribution of distal tibial torsion (DTT) to the total ETT was calculated. Lateralization of the TT relative to the maximum transverse diameter of the tibial plateau was measured according to the method described by Tensho et al. Comparisons between the three groups were conducted using a one-way analysis of variance (ANOVA) with Bonferroni post hoc correction for multiple comparisons. The difference in TTL values between the normal and pathological groups was assessed using Student's t-test. The relationship between the total ETT and the percentage of contribution of DTT was analyzed using Pearson's correlation coefficient. Inter-observer reproducibility was assessed using the intraclass correlation coefficient with two factors and total concordance. All statistical analyses were performed using SPSS software (version 20.0). A p-value of <0.05 was considered statistically significant in all tests.
RESULTS. The percentage of contribution of infratuberositary torsion to the total tibial torsion (TTT) was 18.2% (SD 16.7) in the control group, 22.1% (SD 12.1) in the moderate-torsion group, and 35.2% (SD 11.5) in the high-torsion group (p < 0.01 for the high-torsion group). A moderate significant correlation was found between the degree of TTT and the percentage of contribution of DTT (R = 0.540, p < 0.001, n=197). The linear regression analysis showed that ETT was a significant predictor of the percentage of DTT (p < 0.001). No correlation was found between the lateralization of the TT and the degree of ETT. The control group showed a TTL ratio of 0.65 (SD 0.03), while the pathological group (severe and moderate) had a ratio of 0.65 (SD 0.05), with no statistically significant difference.
CONCLUSION. In the group with severe ETT, there is an increased contribution of the infratuberositary tibia to the rotational deformity. Moreover, an increase in ETT does not result in lateral displacement of the TT.
CLINICAL RELEVANCE. Our findings could serve as a theoretical basis to support the selection of an infratuberositary osteotomy for the correction of severe ETT in AKP female patients.