Characteristic arthroscopic signs of cartilage injuries indicating concomitant occult medial meniscal peripheral tears of posterior horn.

BACKGROUND: Medial posterior horn meniscal tear is difficult to visualise during arthroscopy and is occasionally undetected by preoperative magnetic resonance imaging (MRI). Consequently, attention should be paid to performing a thorough examination and to some characteristic signs that indicate occult meniscal tear. The purpose of this study was to assess an indicative correlation between arthroscopic features of cartilage injury and a concomitant occult meniscal tear.
METHODS: We performed a retrospective clinical and radiographic study of a consecutive series of patients between January 2013 and December 2014. Of 1,596 patients, all 78 with wave-like chondral injury of the medial femoral condyle diagnosed at arthroscopy were included in the study. The occurrence, pattern, location and concomitant pathology of medial meniscal injury were analysed.
RESULTS: The characteristic wave sign associated with chondral injury in the medial femoral condyle was detected by MRI preoperatively in two cases only; all others were discovered intraoperatively at arthroscopy. Cartilage injury was rated as Outerbridge type II in 53 patients, type III in 24, and type IV in one. Wave sign defects were all characterised by their transverse orientation in the load-bearing femoral condyle. The occult longitudinal peripheral meniscus tear of the posterior horn was seen in all patients with a positive wave sign visualised under arthroscopy. The wave sign was positively correlated with medial peripheral meniscal injury of the posterior horn (P < 0.01).
CONCLUSION: Wave sign chondral injury in the medial femoral condyle seen at arthroscopy is a characteristic indicator for concomitant occult medial longitudinal peripheral meniscus tears of the posterior horn. LEVEL OF EVIDENCE: Case series, Level IV.