Trans-Posterior Cruciate Ligament All-Inside Root Repair Versus Partial Meniscectomy for Medial Meniscus Posterior Root Tears: Comparison of Semiquantitative and Quantitative MRI Outcomes in Cartilage Degeneration and Osteoarthritic Progression

Abstract

Objective: To perform conventional, morphological, and T2 mapping compositional MRI imaging to assess the cartilage degeneration and osteoarthritic progression in patients with medial meniscus posterior root tears (MMPRTs) who underwent trans-posterior cruciate ligament (PCL) all-inside repair or partial meniscectomy.

Design: Patients with MMPRTs after trans-PCL all-inside repair (group AR) or partial meniscectomy (group PM) between 2015 and 2018 were retrospectively identified. Preoperative and postoperative conventional MRI were collected to assess medial meniscus extrusion (MME) and the whole-organ magnetic resonance imaging score (WORMS). Postoperative morphological MRI and T2 mapping compositional MRI were collected to evaluate the quantitative cartilage thickness/volume and cartilage composition.

Results: The final cohort consisted of 21 patients in group AR and 22 patients in group PM, with no differences in demographic data and baseline patient characteristics between the 2 groups. Group AR demonstrated less progression of articular cartilage wear (P < 0.05) and decreased meniscal extrusion (P = 0.008) than group PM at the final follow-up. In addition, group AR demonstrated less extracellular matrix degeneration in the cartilage subregion of the medial compartment (P < 0.05) than group PM with lower T2 relaxation times in the superficial layer of the articular cartilage.

Conclusion: Trans-PCL all-inside repair of MMPRTs could delay the initial cartilage deterioration and morphological cartilage degeneration compared with partial meniscectomy. However, the amount of residual meniscal extrusion is clinically important, and an improved root repair fixation method should be investigated.

Keywords: MRI evaluation; all-inside repair; medial meniscus; meniscus root tear.

Figure 1.

Arthroscopic pictures with a 30° arthroscope through the anterolateral portal showing medial meniscus posterior root tear refixation to the adjacent posterior cruciate ligament by the all-inside repair technique. (A) Black arrow: complete radial tear of medial meniscus posterior root; (B) black star: posterior cruciate ligament; black arrow: the torn meniscus root was refixed to the adjacent posterior cruciate ligament fibers. Confirmation of improved meniscal tension and stability after refixation by probing.

Figure 2.

Measurement of medial meniscus extrusion. Medial meniscus extrusion was measured from the tangent perpendicular to the medial tibial edge and the lateral edge of the medial meniscus on coronal MRI at the level of the medial collateral ligament.

Figure 3.

Definition of the regions for analysis of cartilage volume in the femoral condyles and tibial plateau. (A) The medial and lateral femoral condyles were further segmented into anterior (Fa), central (Fc), and posterior (Fp) subregions. The central region was defined relative to the anterior and posterior aspect of the proximal tibia (at the margin of the tibial plateau). (B) The medial and lateral tibial subregions were further segmented into the regions uncovered (UNC) and covered by the meniscus (COV). MT = medial tibia; LT = lateral tibia.

Figure 4.

(A) Regions of interest (ROI) segmentation of the medial tibiofemoral compartment. The MFC and MT were segmented manually into 5 and 3 subregions, respectively, according to the meniscus. Each subregion was assessed by further segmenting full-thickness cartilage into 2 approximately equal sections. MFC-3 and MT-2 are contacting regions of femoral and tibial cartilage during standing. MFC-2, MFC-4 and MT-1, MT-3 are regions above and below the meniscal horn, respectively. MFC-1 and MFC-5 are non-weightbearing portions of the femoral condyle during standing. T2 mappings of the MMPRTs after surgery. (B) Mean T2 values from superficial and deep layers in each defined subregions, as shown in (A), were recorded. MFC = medial femoral condyle; MT = medial tibia; MMPRTs = medial meniscus posterior root tears.

Figure 5.

Flowchart of included participants. MMPRTs = medial meniscus posterior root tears; TKA = total knee arthroplasty.

Figure 6.

Coronal MRI at the final follow-up. (A) MRI of patient with trans-posterior cruciate ligament all-inside repair demonstrating medial meniscus extrusion (1.29 mm). (B) MRI of patient with partial meniscectomy demonstrating medial meniscus extrusion (8.70 mm).