The clinical and radiographic outcomes of type 2 medial meniscus posterior root tears following transtibial pullout repair

Purpose The aim of this study was to compare the clinical outcomes of different subtypes of type 2 medial meniscus posterior root tears following transtibial pullout repair. Methods In total, 147 patients (mean age: 66.2 +/- 8.3 years) who were diagnosed with type 2 medial meniscus posterior root tears and underwent transtibial pullout repair were included. Patients were divided into 2A (n = 31), 2B (n = 90), and 2C (n = 26) groups according to tear type. Clinical outcomes were assessed pre-operatively and at second-look arthroscopy using the Knee injury and Osteoarthritis Outcome Score. The meniscal healing status was evaluated at second-look arthroscopy. Medial meniscus extrusion was calculated using magnetic resonance imaging pre-operatively and at second-look arthroscopy. Results No significant differences in pre-operative or post-operative clinical scores were observed between each subtype, although clinical scores improved post-operatively for each subtype. Significant differences were noted in the anteroposterior width of the bridging tissues at second-look arthroscopy (2A, 7.1 +/- 1.2; 2B, 6.2 +/- 1.7; and 2C, 6.2 +/- 1.7 mm; p = 0.045); type 2A tears were the widest. There was a significant difference in post-operative medial meniscus extrusion (2A, 3.2 +/- 0.9; 2B, 4.0 +/- 1.2; and 2C, 4.0 +/- 1.4 mm; p = 0.004) and its progression (2A, 0.7 +/- 0.6; 2B, 1.2 +/- 0.8; and 2C, 1.2 +/- 0.8 mm; p= 0.008), and type 2A tears were the shortest. Conclusion Although there was no significant difference in the post-operative clinical scores among different type 2 tears in the short term, type 2A tears showed better healing and medial meniscus extrusion progression prevention, thus indicating the usefulness of classifying tear type in estimating post-operative outcomes.