Lateral meniscal posterior root tears experience acceptable healing status after transtibial repair technique

Purpose To evaluate patient MRI results, demography and clinical outcome following transtibial repair of lateral and medial meniscal posterior root tears. Methods Patients treated with transtibial repairs of posterior meniscal root tears from 2015 through 2018 performed pre- and postoperative MRI scans. Outcome measures were continuity/discontinuity of the meniscal root and change in meniscal extrusion on MRI. Other outcomes were KOOS, Lysholm score, Tegner activity scale and the Global Rate of Change (GRoC) score for function and pain at follow-up. Study design Retrospective case-series. Results Of 41 patients, 36 attended follow-up at mean 26 (12–38) months postoperatively. At follow-up, 11 out of 18 lateral meniscus posterior root tear (LMPRT) versus 5 out of 18 medial meniscus posterior root tear (MMPRT) repairs were classified as healed. Meniscal extrusion decreased in LMPRTs from of 2.3 ± 1.5 mm to 1.4 ± 1.09 mm (p = 0.080) and increased in MMPRTs from 3.1 ± 1.6 mm to 4.8 ± 1.9 mm (p = 0.005) at FU (between-group difference, p < 0.001). LMPRT repairs were associated with ACL injury and additional meniscal injury and were younger and with lower BMI. No between-group differences were found for KOOS, Lysholm or GRoC Function scores. Tegner scale was higher and GRoC Pain score lower in the LMPRT group compared to the MMPRTs. Conclusion Following transtibial repair for meniscal posterior root repairs, the LMPRTs had a higher frequency of healing, whereas most MMPRTs continued to extrude, despite surgical intervention. The study confirmed that LMPRTs and MMPRTs differ in demography and associated injuries.

Intradural lumbar radicular arteriovenous malformation mimicking perimedullary arteriovenous malformation of the conus medullaris: illustrative case

BACKGROUND Intradural radicular arteriovenous malformation (AVM) of the cauda equina is a rare entity of spinal AVMs. Because of the specific arterial supply of the conus medullaris and cauda equina, AVMs in this area sometimes present with confusing radiological features. OBSERVATIONS The authors reported a rare case of intradural radicular AVM arising from the lumbar posterior root. The patient presented with urinary symptoms with multiple flow void around the conus medullaris, as shown on magnetic resonance imaging. Digital subtraction angiography demonstrated arteriovenous shunt at the left side of the conus medullaris fed by the anterior spinal artery via anastomotic channel to the posterior spinal artery and rich perimedullary drainers. There was another arteriovenous shunt at the L3 level from the left L4 radicular artery. Preoperative diagnosis was perimedullary AVM with radicular arteriovenous fistula. Direct surgery with indocyanine green angiography revealed that the actual arteriovenous shunt was located at the left L4 posterior root. The AVM was successfully treated by coagulation of feeding branches. LESSONS Unilateral arteriovenous shunt fed by either posterior or anterior spinal artery at the conus medullaris may include AVM of the cauda equina despite abundant perimedullary venous drainage. Careful pre- and intraoperative diagnostic imaging is necessary for appropriate treatment.

Quantifying the differential functional behavior between the medial and lateral meniscus after posterior meniscus root tears

Meniscus tears of the knee are among the most common orthopedic knee injury. Specifically, tears of the posterior root can result in abnormal meniscal extrusion leading to decreased function and progressive osteoarthritis. Despite contemporary surgical treatments of posterior meniscus root tears, there is a low rate of healing and an incidence of residual meniscus extrusion approaching 30%, illustrating an inability to recapitulate native meniscus function. Here, we characterized the differential functional behavior of the medial and lateral meniscus during axial compression load and dynamic knee motion using a cadaveric model. We hypothesized essential differences in extrusion between the medial and lateral meniscus in response to axial compression and knee range of motion. We found no differences in the amount of meniscus extrusion between the medial and lateral meniscus with a competent posterior root (0.338mm vs. 0.235mm; p-value = 0.181). However, posterior root detachment resulted in a consistently increased meniscus extrusion for the medial meniscus compared to the lateral meniscus (2.233mm vs. 0.4705mm; p-value < 0.0001). Moreover, detachment of the posterior root of the medial meniscus resulted in an increase in extrusion at all angles of knee flexion and was most pronounced (4.00mm ± 1.26mm) at 30-degrees of knee flexion. In contrast, the maximum mean extrusion of the lateral meniscus was 1.65mm ± 0.97mm, occurring in full extension. Furthermore, only the medial meniscus extruded during dynamic knee flexion after posterior root detachment. Given the differential functional behaviors between the medial and lateral meniscus, these findings suggest that posterior root repair requires reducing overall meniscus extrusion and recapitulating the native functional responses specific to each meniscus.

Potential of the non-weight-bearing tunnel view in diagnosing medial meniscus posterior root tear: a pilot study of X-ray characteristics

Purpose Early detection of medial meniscus posterior root tear (MMPRT) is important in preventing the rapid onset and progression of degenerative knee disease. Diagnosis is facilitated by the availability of non-weight-bearing X-ray view, but information on the X-ray characteristics of MMPRT is scarce. Here, we conducted a pilot study of the X-ray characteristics of MMPRT on non-weight-bearing tunnel view. Methods We retrospectively reviewed 43 consecutive patients treated in the outpatient department for medial knee pain or popliteal pain. Patients were divided into MMPRT (21 knees) and non-MMPRT groups (22 knees). We investigated X-ray characteristics and magnetic resonance imaging findings. Femorotibial angle, posterior tibial slope, medial tibial eminence (MTE)–medial femoral condyle (MFC) distance (contralateral and affected sides, and difference between the two), medial tibiofemoral joint (MTFJ) width (contralateral and affected sides, and difference between the two), and meniscus radial dislocation between the groups were evaluated using the Mann–Whitney U test. The association between X-ray characteristics and MMPRT was determined using univariate and multivariate logistic regression analyses. Results A highly significant difference between the affected and contralateral sides was seen in MTFJ width and MTE–MFC distance on non-weight-bearing tunnel view between the MMPRT and non-MMPRT groups. Moreover, a difference in MTFJ width of <−0.575 mm and in MTE–MFC distance of >0.665 mm between the affected and contralateral sides was useful in predicting MMPRT. Conclusions The non-weight-bearing tunnel view is useful for the initial diagnosis of MMPRT. Prospective evaluation in a larger population is warranted.

A characteristic MRI finding to diagnose a partial tear of the medial meniscus posterior root: an ocarina sign

Background Diagnosing partial tears of the medial meniscus (MM) posterior root is difficult. The aim of this study was to evaluate diagnostic values involved in conventional magnetic resonance imaging (MRI) features of MM posterior root tears (MMPRTs) and find other MRI-based findings in patients with partial MMPRTs. Methods Eighteen patients who had arthroscopically confirmed partial MMPRTs were included. As a control, 18 patients who underwent partial meniscectomy for other types of MM tears were evaluated. Isolated partial MMPRTs were classified into the following three types: type A, accurate partial stable tear (cleavage < 1/2 of root width); type B, bridged unstable root tear (cleavage ≥ 1/2 of root width); type C, complex horn tear expanded to the root. Conventional MRI-based findings of MMPRTs were evaluated between two groups (n = 23). Posterior root irregularity, bone marrow spot, and ocarina-like appearance showing several condensed circles in triangular meniscal horn (ocarina sign) were also evaluated. Results Posterior root irregularity and bone marrow spot were frequently observed in the partial MMPRTs (47.8%), compared with the other MM tears (P = 0.007 and 0.023, respectively). The ocarina sign was detected in 69.6% of patients with partial MMPRTs. A significant difference between two groups was observed in a positive ratio of ocarina sign (P < 0.001). Types A, B, and C of the partial tear/damage were observed in three, eight, and seven patients, respectively. The ocarina sign was the most common MRI finding in each type of partial MMPRT. Conclusions This study demonstrated that a characteristic MRI finding, “ocarina sign,” was frequently observed in patients with partial tear/damage of the MM posterior root. The ocarina sign was the most common MRI finding in several types of partial MMPRTs. Our results suggest that the ocarina sign may be useful to diagnose unnoticed partial MMPRTs. Level of evidence: IV, retrospective comparative study.

Comparison of Clinical Efficacy Between Arthroscopically Assisted Gracilis Autograft With Suture Reinforcement Technique and Transtibial Pull-out Technique in Treating Medial Meniscus Posterior Root Tears

Background: To compare the short-term efficacy of the transtibial pull-out technique and gracilis autograft with suture reinforcement technique in the treatment of medial meniscus posterior root tears. Methods: A total of 64 patients with medial meniscus posterior root tears received reconstruction of the posterior root of the meniscus attachment point through the tibial tunnel between June 2018 and April 2019 were included in this study, patients were divided into 2 groups (transtibial pull-out technique group: 35 cases; gracilis autograft with suture reinforcement technique group: 29 cases) according to the different posterior meniscus root tear repair methods. Clinical outcomes were evaluated by the visual analogue scale (VAS) and Lysholm score and IKDC score, and the demographics and functional recovery of the knee were compared between the two groups.Results: Intraoperative and postsurgical complications such as infection were not found in the two groups, and there was a statistically significant improvement in the Lysholm score，IKDC score and VAS score (P<0.001; respectively). All the patients were very satisfied with the function of their knee at the last follow-up. However, compared with the transtibial pull-out repair group, the reinforced medial meniscal root reconstruction technique with gracilis autograft group were significant improvement in the meniscus healing rates and Lysholm score, IKDC score and VAS score at the end of follow-up (P<0.05; respectively).Conclusions: Compared with the transtibial pull-out technique, the reinforced medial meniscal root reconstruction technique with gracilis autograft is advantageous for treating these patients because it is a minimally invasive procedure with superior clinical outcome and meniscus healing rates.Levels of Evidence: Ⅲ, Case-control study Retrospective comparative study