Abstract
Introduction and Aims: A number of x-ray appearances have been identified as indicative of discoid menisci. None are reliable or statistically significant. The purpose of this paper is to identify a reliable radiographic sign, diagnostic of the discoid lateral meniscus.
Method: The anteroposterior view radiographs of 14 knees in 13 patients with arthroscopically proven discoid meniscus were studied. Ages ranged from 11 to 26, with a mean age of 18.4 ± 4.84 years, right to left ratio 9/5, male to female ratio 8/5. Fifteen normal knees in 14 people were used as a control group, age from 11 to 30, mean age 16.20 ± 6.41, right to left ratio 8/7, male to female ratio 6/8. The parameters measured were: Lateral Joint Space (LJS); Height of the Lateral Tibial Spine (LTS); change of the Medial Tibial Spine (MTS); Height of Fibular Head (HFH); changes of the Edge of the Lateral Tibial Plateau (ELTP), cupping of the lateral tibial plateau, and squaring of the lateral femoral condyle.
Results: There was no significant difference between the two groups in LJS, height of LTS, cupping of the lateral tibial plateau, and squaring off of the lateral femoral condyle. There was a difference between the two groups in HFH which was statistically significant at an absolute value of p = 0.033, but not significant in normalised value p = 0.056. The medial tibial spine was sharpened in three patients.
There were 12 positive changes on ELTP out of 14 patients (85.71%) in the discoid group, while only one positive of 15 (6.67%) in the normal group, and the difference between the two groups was statistically significant at p< 0.01. The diagnosis parameters were Sensitivity (Se) = 85.71%, Specificity (Sp) = 93.33%, Positive predictive value (PV+) = 92.31%, Negative predictive value (PV−) = 87.50%, Correct rate (ñ) = 89.66%. The typical change on the edge of lateral tibial plateau is sharpening and/or formation of a spur.
Conclusion: Sharpening with spur formation on the edge of lateral tibial plateau is a diagnostic radiological sign of a discoid lateral meniscus.
These abstracts were prepared by Editorial Secretary, George Sikorski. Correspondence should be addressed to Australian Orthopaedic Association, Ground Floor, The William Bland Centre, 229 Macquarie Street, Sydney, NSW 2000, Australia.
At least one of the authors is receiving or has received material benefits or support from a commercial source.
