Comparison of the insertion of the posterior horn of the lateral meniscus: discoid versus non-discoid.

PURPOSE: The purpose of this study was to compare the insertion sites of the posterior horn between discoid and non-discoid lateral meniscus using magnetic resonance imaging (MRI). METHODS: Two hundred and twenty-seven patients who had MRI scans before surgery and underwent arthroscopy were enroled in this study. A coronal view showing the narrowest width of the midbody of the lateral meniscus was chosen to measure the widths of the entire tibial plateau and the midbody of the lateral meniscus. Considering the ratio of the meniscal width to the tibial plateau width, the patients were divided into non-discoid, incomplete discoid, and complete discoid groups. On a coronal view accurately showing the insertion of the posterior horn of the lateral meniscus, a distance between the peak of the lateral tibial eminence and the centre of the insertion of the posterior horn, and a width of the lateral tibial plateau between the lateral edge of the tibial plateau and the peak of the lateral tibial eminence were measured. RESULTS: The insertion centre of the posterior horn was located more medially in the incomplete and complete discoid groups than in the non-discoid group (p = 0.003, 0.010, respectively). When individual differences in the knee size were corrected, the insertion centre of the posterior horn in the incomplete discoid and complete discoid groups was located more medially than in the non-discoid group (p = 0.009, 0.003, respectively). CONCLUSION: The insertion centre of the posterior horn of the lateral meniscus is located more medially to the apex of the lateral tibial eminence in the discoid group than in the non-discoid group. This finding needs to be considered for an accurate position of the posterior horn of lateral meniscus during the lateral meniscal allograft transplantation. LEVEL OF EVIDENCE: IV.

The Use of T1 Sagittal Angle in Predicting Cervical Disc Degeneration.

STUDY DESIGN: Retrospective evaluation. PURPOSE: To analyze the effect of T1 slope on degree of degeneration in patients with cervical disc degeneration. OVERVIEW OF LITERATURE: The T1 slope is well known parameter that may be very useful in evaluating sagittal balance. There are no reports on the analysis of the relationship between T1 slope and cervical disc degeneration. We hypothesized that T1 slope has an effect on the degree of cervical degeneration. METHODS: Sixty patients who had cervical spine magnetic resonance imaging (MRI) in our orthopedic clinic were enrolled. Patients were divided into two groups according to T1 slope. Radiologic parameters obtained from radiography and cervical spine MRI were compared between low T1 slope group (≤25) and high T1 slope group (>25). RESULTS: Among low T1 slope group, average degeneration grade of each cervical segment was 2.65 in C2-3, 2.50 in C3-4, 2.62 in C4-5, 3.23 in C5-6, and 2.81 in C6-7. And that of high T1 group was 2.35 in C2-3, 2.32 in C3-4, 2.59 in C4-5, 2.79 in C5-6, and 2.32 in C6-7. Grade of degeneration of low T1 group was significantly higher, as compared with high T1 group in C5-6 (p=0.028) and C6-7 (p=0.009). Percentage of high grade degeneration of more than grand III was 65.4% in low T1 group and 32.4% in high T1 group (p=0.018). Risk of high grade degeneration of C6-7 was significantly higher in low T1 group (odds ratio, 5.63; 95% confidence interval, 1.665-19.057; p=0.005). CONCLUSIONS: Patients with low T1 slope had higher grade of degeneration regardless of age and gender. Low T1 slope is a potential risk factor of cervical spondylosis especially in the C6-7 cervical segment.