The role of MRI in evaluation of arthroscopic transtibial pullout repair for medial meniscus posterior root tears

More than 3 mm of preoperative medial meniscal extrusion is identified as a key risk factor for varus progression in limb alignment after arthroscopic repair of medial meniscus posterior root tear

PURPOSE

To investigate the risk factors for varus progression after arthroscopic medial meniscal posterior root tear (MMPRT) repair and to compare the clinical outcomes between two groups: one with more varus progression and the other with less varus progression.

METHODS

Patients who underwent isolated arthroscopic repair of MMPRT between 2015 and 2020 were enroled, and 2-year follow-up data were collected. Participants were categorized into two groups based on preoperative values of the weight-bearing line (WBL) ratio: group A with <5.9% increase and group B with ≥5.9% increase. Various factors, including demographic features and radiological findings, were analysed and compared between the two groups. Intra-meniscal signal intensity, meniscal healing, medial meniscal extrusion (MME), and articular cartilage grade were assessed preoperatively and 1-year postoperatively using coronal magnetic resonance imaging.

RESULTS

The final cohort consisted of 34 patients in group A and 46 in group B, with a mean age of 55.8 ± 11.2 and 59.8 ± 6.6 years, respectively. Preoperative WBL ratio and cartilage lesions in the medial compartment did not differ between the groups. Preoperative MME were significantly lower in group A than those in group B (2.6 ± 0.6 mm in group A and 3.5 ± 0.7 mm in group B, p < 0.05). Patient-reported outcomes at the 2-year follow-up did not differ between the two groups (n. s.). In a logistic analysis, the odds ratio of MME was 2.1 (p < 0.05), and the cutoff value of MME was 3.02 mm.

CONCLUSION

Preoperative MME is a risk factor for varus progression. However, no differences in patient-reported outcomes were observed at 2-year follow-up, even in the group with greater varus progression.

LEVEL OF EVIDENCE

Level IV.

Signal intensity of repaired posterior roots after transtibial pullout repair for medial meniscus posterior root tears in stable knees: Magnetic resonance imaging evaluations at 3 years postoperatively

BACKGROUND

Only a few studies have assessed signal intensity after pullout repair for medial meniscus posterior root (MMPR) tears (MMPRTs) based on mid-term magnetic resonance imaging (MRI) evaluations. Therefore, this study aimed to assess the quantitative signal intensity of repaired posterior roots over time, up to 3 years postoperatively, and the related factors.

METHODS

This study included 36 patients who underwent pullout repair for MMPRTs and MRI examinations using the same MRI system. The signal intensity of the repaired posterior roots was quantitatively evaluated using the signal-to-noise quotient (SNQ). Medial meniscus extrusion (MME), the SNQ for MMPR, and clinical scores were assessed over 3 years postoperatively.

RESULTS

MME progressed over time until 3 years postoperatively, and its progression during this period was 1.61 ± 1.44 mm. The SNQ for MMPR decreased over time until 3 years postoperatively, and the change in the SNQ from 3 months to 3 years postoperatively (ΔSNQ) was 2.69 ± 1.69. All clinical scores significantly improved (p < 0.001). ΔSNQ was significantly correlated with body weight (correlation coefficient = -0.424, p = 0.010) and body mass index (correlation coefficient = -0.330, p = 0.050). However, ΔSNQ was not significantly correlated with preoperative or postoperative clinical scores.

CONCLUSION

After pullout repair for MMPRTs, MME progressed to 3 years postoperatively. However, the signal intensity of the repaired posterior roots decreased, and clinical scores improved over time until 3 years postoperatively. Patient weight and body mass index were significantly correlated with the reduced signal intensity of the repaired posterior roots, suggesting that weight assessment in patients with MMPRTs is crucial.

LEVEL OF EVIDENCE

IV.

The stability of repaired meniscal root can affect postoperative cartilage status following medial meniscus posterior root repair

BACKGROUND

Transtibial pullout repair yields beneficial clinical outcomes in patients with medial meniscus (MM) posterior root tear. However, the relationship between repaired meniscal root healing status and postoperative clinical outcomes remains unclear. We aimed to evaluate changes in articular cartilage damage and clinical scores after pullout repair using two simple stitches (TSS).

METHODS

Thirty-three patients who underwent pullout repair using TSS were assessed. Healing status was assessed by a semi-quantitative second-look arthroscopic scoring system comprising three evaluation criteria (width of bridging tissues, stability of the repaired root, and synovial coverage), 1 year postoperatively. MM medial extrusion (MMME) and cartilage damage were assessed preoperatively and 1 year postoperatively. The medial compartment was divided into 8 zones (A-H) for comparison of preoperative and 1-year postoperative cartilage damage. Clinical outcomes were evaluated using the Knee Injury and Osteoarthritis Outcome score, Lysholm score, International Knee Documentation Committee scores, and visual analogue scale pain score.

RESULTS

Although cartilage damage did not aggravate significantly in most medial compartment areas, MMME progressed at 1 year postoperatively. No statistical differences were observed in cartilage damage between the central-to-medial area of the medial femoral condyle and the medial tibial plateau area at 1 year postoperatively. Regarding semi-quantitative healing scores, the stability score was significantly correlated with the International Cartilage Repair Society grade at 1 year postoperatively. All 1-year and 2-year clinical scores significantly improved compared with the preoperative scores.

CONCLUSION

Regarding TSS repair, stability of repaired meniscal root negatively correlated with cartilage damage in the medial compartment loading area. All 1-year and 2-year clinical scores significantly improved than those of the preoperative scores. Achieving MM stability is crucial for suppressing cartilage degeneration.

LEVEL OF EVIDENCE

IV case series study.

Reprint of: Outcomes of Arthroscopic All-Inside Repair Are Improved Compared to Transtibial Pull-Out Repair of Medial Meniscus Posterior Root Tears

PURPOSE

The purpose of the present study was to compare the clinical outcomes of patients who underwent an all-inside repair (with a bony trough) versus transtibial pull-out repair in medial meniscus posterior root tears (MMPRTs).

METHODS

We retrospectively investigated consecutive patients who underwent MMPRT repairs in nonacute tears in age over 40 from November 2015 to June 2019. All patients were divided into a transtibial pull-out repair group and an all-inside repair group. Different surgical techniques were used during different time frames. All patients were followed-up for a minimum of 2 years. The data collected included the International Knee Documentation Committee (IKDC) Subjective, Lysholm, and Tegner activity scores. Magnetic resonance imaging (MRI) was performed at the 1-year follow-up to assess meniscus extrusion, signal intensity, and healing.

RESULTS

The final cohort consisted of 28 patients in the all-inside repair group and 16 in the transtibial pull-out repair group. In the all-inside repair group, the IKDC Subjective, Lysholm, and Tegner scores improved significantly at the 2-year follow-up. In the transtibial pull-out repair group, the IKDC Subjective, Lysholm, and Tegner scores did not improve significantly at the 2-year follow-up. Postoperative extrusion ratio increased in both groups, and patient-reported outcomes at follow-up did not differ between the two groups The change in the extrusion ratio was significantly less in the all-inside repair group (P = .009), as was the postoperative meniscus signal (P = .011). Postoperative MRI revealed significantly better healing in the all-inside group (P = .041).

CONCLUSION

All-inside repair improved the functional outcome scores. Radiologically, all-inside repair was better than transtibial pull-out repair. All-inside repair may be a viable MMPRT treatment option.

LEVEL OF EVIDENCE

III, retrospective cohort study.

Outcomes of Arthroscopic All-Inside Repair Are Improved Compared to Transtibial Pull-Out Repair of Medial Meniscus Posterior Root Tears

PURPOSE

The purpose of the present study was to compare the clinical outcomes of patients who underwent an all-inside repair (with a bony trough) versus transtibial pull-out repair in medial meniscus posterior root tears (MMPRTs).

METHODS

We retrospectively investigated consecutive patients who underwent MMPRT repairs in nonacute tears in age over 40 from November 2015 to June 2019. All patients were divided into a transtibial pull-out repair group and an all-inside repair group. Different surgical techniques were used during different time frames. All patients were followed-up for a minimum of 2 years. The data collected included the International Knee Documentation Committee (IKDC) Subjective, Lysholm, and Tegner activity scores. Magnetic resonance imaging (MRI) was performed at the 1-year follow-up to assess meniscus extrusion, signal intensity, and healing.

RESULTS

The final cohort consisted of 28 patients in the all-inside repair group and 16 in the transtibial pull-out repair group. In the all-inside repair group, the IKDC Subjective, Lysholm, and Tegner scores improved significantly at the 2-year follow-up. In the transtibial pull-out repair group, the IKDC Subjective, Lysholm, and Tegner scores did not improve significantly at the 2-year follow-up. Postoperative extrusion ratio increased in both groups, and patient-reported outcomes at follow-up did not differ between the two groups The change in the extrusion ratio was significantly less in the all-inside repair group (P = .009), as was the postoperative meniscus signal (P = .011). Postoperative MRI revealed significantly better healing in the all-inside group (P = .041).

CONCLUSION

All-inside repair improved the functional outcome scores. Radiologically, all-inside repair was better than transtibial pull-out repair. All-inside repair may be a viable MMPRT treatment option.

LEVEL OF EVIDENCE

III, retrospective cohort study.

Increased cleft width during knee flexion is useful for the diagnosis of medial meniscus posterior root tears

PURPOSE

This study aimed to evaluate changes in the cleft width, defined as the distance between the lateral edge of the medial tibial plateau and that of the medial meniscus (MM) posterior root, using open magnetic resonance imaging (MRI) in patients with MM posterior root tear (MMPRT).

METHODS

This study included 25 patients (20 women and 5 men; mean age: 65.2 years) who were diagnosed with MMPRT and underwent pullout repair. Upon coronal imaging, the cleft width was evaluated at the 10° and 90° flexed knee positions. The difference in the cleft width (defined as the cleft width at 90° minus the cleft width at 10°) was also calculated. Upon sagittal imaging, the MM posterior extrusion (MMPE) at 90° was also evaluated. Separate univariate linear regression models were used to determine the association between the time from injury to MRI and radiographic measurements.

RESULTS

The mean cleft width at 10° and 90° was 4.9 ± 2.6 mm and 7.4 ± 3.7 mm, respectively; the mean difference in cleft width was 2.5 ± 1.5 mm, and the mean MMPE at 90° was 3.7 ± 1.3 mm. There was a significant difference in cleft width at 10° and 90° (p < 0.001). The time from injury to MRI was significantly associated with the cleft width at 10° (R = 0.42; p = 0.023), cleft width at 90° (R = 0.59; p = 0.002), the difference in the cleft width (R = 0.62; p = 0.008), and MMPE at 90° (R = 0.53; p = 0.008).

CONCLUSION

This study demonstrates that the cleft width is significantly larger during knee flexion than during knee extension. Increased cleft width during knee flexion ("graben" sign) may help diagnose MMPRT, especially in cases where the cleft sign is unclear during knee extension.

LEVEL OF EVIDENCE

III.

Meniscal Root Tears: An Update Focused on Preoperative and Postoperative MRI Findings

Meniscal root tears represent radial tears or avulsions of the meniscal cartilage at the tibial attachment site that profoundly affect meniscal biomechanics and kinematics. Meniscal root tears have the functional effect of a total meniscectomy and can lead to rapid degenerative change with development of early knee osteoarthritis (OA). A growing range of arthroscopic surgical techniques have been developed to repair meniscal root tears with the aim of restoring joint kinematics and contact pressures and delaying the development of OA. With increased understanding of the anatomy and biomechanics of the meniscal root, meniscal root injury repair has become the treatment of choice in knees with nonadvanced OA. This article reviews the anatomy and biomechanics of the meniscal roots, clinical and imaging diagnostic criteria of meniscal root tears, correlation between arthroscopy and MRI in the diagnosis and classification of meniscal root tears, and expected and abnormal MRI findings after meniscal root repair. Familiarity with MRI signs and classifications of meniscal root tears, as well as with root repair surgical techniques, can aid radiologists in correctly reporting preoperative and postoperative MRI findings.

A posterior anchoring method decreases pullout suture translation of the medial meniscus posterior root repair during knee flexion

BACKGROUND

The medial meniscus (MM) translates posteriorly and extrudes severely from the medial tibial plateau (MTP) during knee flexion in the MM posterior root tear (PRT) knee. Transtibial pullout repair of the MMPRT has been performed to regulate MM extrusion. This study aimed to evaluate pullout suture translation during knee flexion before and after posterior anchoring during pullout repair. We hypothesized that suture translation after posterior anchoring would be significantly decreased relative to that before posterior anchoring.

METHODS

Thirty-five patients who underwent MM posterior root repair were prospectively investigated. Pullout repair was performed using two cinch sutures (outer and inner sutures) and posterior anchoring through the MM posterior horn and an additional bone tunnel on the MTP. The translation of the outer suture from 0° to 90° of knee flexion was measured and compared before and after posterior anchoring intraoperatively. The MM morphologic features were measured using preoperative magnetic resonance imaging, and the correlation between these values and outer suture translation was evaluated.

RESULTS

The average outer suture translation after posterior anchoring (1.6 ± 1.5 mm) was significantly decreased relative to that before posterior anchoring (2.5 ± 1.7 mm, P < 0.01). No significant correlations were observed between the MM morphological features and outer suture translation.

CONCLUSIONS

The posterior anchoring method with an MM posterior root repair is useful in decreasing posterior translation of the pullout suture during knee flexion, which might have an advantage in preventing suture pullout from the repaired MM, leading to good clinical outcomes.