Summary

The findings of this study showed that in patients who had medial meniscus posterior root tears, an increased opening in the lateral joint space width was observed under varus stress x-rays conditions.

Abstract

Aim

Medial meniscus posterior root tear (MMPRT) causes meniscal extrusion, loss of meniscus function and it is associated with development of medial compartment arthritis. The gold standard for diagnosis for MMPRT is arthroscopic visualization; however magnetic resonance imaging (MRI) is also used for the confirmation of diagnosis of MMPRTs. The aim of this study was to evaluate the utility of stress X-rays in the diagnosis of MMPRT.

Methods

This retrospective comparison study was approved by the local ethical board. Twenty patients who had undergone knee arthroscopy and high tibial osteotomy between March 2015 and May 2016 and whose preoperative bilateral varus and valgus stress x-rays (Telos device) along with weight bearing x-rays were available were included. These patients were grouped into two according to integrity of posterior roots of their medial menisci being either torn (study group) or intact (control group) which was confirmed arthroscopically; there were ten patients both in the study and control groups (mean age of whom were 54.00±5.25 and 55.90±3.70 respectively). Lateral joint space width (LJW) on varus stress x-rays, medial joint space width (MJW) on valgus stress x-rays as well as LJW and MJW on weight bearing x-rays were measured bilaterally. Intragroup comparisons of joint space widths between index and opposite knees were performed. Differences of MJW and LJW between index and opposite knees as well as the differences of joint space widths between stress x-rays and weight bearing x-rays were calculated. The changes in joint space widths between the two groups were compared. Statistical analyses were performed utilizing SPSS 18.0. The distribution of all variables in both groups was normal tested with one sample Kolmogorov-Smirnov test. Paired and independent samples t-tests were performed. Significance level was set at 0.05.

Results

In MMPRT group, opening of LJ space of index knees under varus stress was greater than that of opposite knees (Index: (mean ± SD) 10.27±1.17mm, opposite: 8.61±1.37mm; p<0.0001). In the control group the difference was not significant (Index: 9.29±2.55mm, opposite: 9.68±1.44 mm; p=0.566). The difference in the opening of LJW (under varus stress) between index and opposite knees was significantly greater in the study group (p=0.013). The difference between LJW under weight-bearing and varus stress conditions was significantly greater in the study group. (Study: 3.64±0.217mm, control: 2.28±0.182 mm, p=0.018).

Conclusion

The findings of this study showed that in patients who had MMPRTs, an increased opening in the LJW was observed under varus stress conditions. This may be relevant with the fact that when varus stress is applied, meniscal extrusion is increased in case of a MMPRT. Stress x-rays could be a useful tool in the diagnosis of MMPRTs.