Dial test——Unidentified predictive factors for the medial meniscus posterior root tears
Objective To evaluate the effect of medial meniscal posterior root tear(MMPRT)on tibi-al external rotation through the dial test and assess the effect of pull-out repair for MMPRT on patho-logical tibial rotation.Methods Totally 40 patients undergoing MMPRT repair using pull-out way be-tween January 2022 and January 2023 were studied retrospectively.The dial test at 30°/90° knee flex-ion was performed on the affected and healthy sides of the patients before and after surgery to assess the tibial external rotation.Results The mean age of the 40 patients was 56.4±7.5 years,with a mean body mass index(BMI)of 24.1±3.0.Among them,6 were male(34%)and 34 were female(85%).The median time from injury to surgery was 3.8±2.9 months.The preoperative tibial external rotation angles measured by the dial test at 30°and 90°knee flexion were 31.34±5.38°and 36.75°±6.62°respectively.Postoperatively,these angles decreased significantly to 24.24°±5.88°and 24.76°±5.47°,respectively(P=0.00).Moreover,significant differences were observed in the changes in tibial external rotation angles of the affected knee before and after surgery,7.10°(95%CI[6.01°,8.19°])at 30°flexion and 11.99°(95%CI[10.68°,13.29°])at 90°flexion.The gap in the tibial external rotation angle between the affected and unaffected sides were significant before surgery at 30°(8.33°,95%CI[7.32°,9.33°])and 90°(13.03°,95%CI[11.82°,14.23°])flexion but not after surgery at 30°(0.48°,95%CI[-0.25°,0.98°])and 90°(0.34°,95%CI[-0.02°,0.70°])flexion.Conclusion The dial test finds increased tibial external rotation in patients with MMPRT,and pull-out repair can correct this pathological tibial external rotation.Moreover,an increased tibial external rotation angle measured by the dial test at 30°and 90°can indicate MMPRT.Therefore,special attention should be given to inter-preting the results of the dial test in cases of MMPRT.