Meniscus-stabilizing function of the meniscofemoral ligament: experimental study of pig knee joints

Posterior Horn Lateral Meniscal Oblique Radial Tear in Acute Anterior Cruciate Ligament Reconstruction Incidence and Outcomes After All-Inside Repair: Clinical and Second-Look Arthroscopic Evaluation

BACKGROUND

The term posterior horn lateral meniscal oblique radial tear (LMORT) has emerged to characterize the tear patterns of the lateral meniscus in many patients with acute anterior cruciate ligament (ACL) injury. There is a lack of data regarding the exact incidence according to the types of LMORT and clinical outcomes.

PURPOSES

(1) To investigate the incidence of LMORT according to type in patients with acute ACL reconstruction (ACLR) and (2) to identify healing status after repair of LMORT via second-look arthroscopy and clinical outcomes.

STUDY DESIGN

Case series; Level of evidence: 4.

METHODS

Patients who underwent primary ACLR within 6 months of injury were retrospectively reviewed. The LMORT was classified into 4 types based on the severity and distance from the root: type 1 (partial tear <10 mm from the root), type 2 (complete tear <10 mm from the root), type 3 (partial tear >10 mm from the root), type 4a (complete tear >10 mm from the root), and type 4b (type 4a with longitudinal tear at the meniscocapsular junction). Only patients with LMORT were isolated, and the clinical outcomes were compared according to the healing status of LMORT in second-look arthroscopy.

RESULTS

Of 635 patients with ACLR, LMORT was identified in 97 patients (15.3%), and type 4 LMORT accounted for the largest proportion (n = 62; 32.6%) of 190 lateral meniscal tears. In 79 patients with LMORT who satisfied the 2-year follow-up period, all patient-reported outcomes (PROs), including the Lysholm (preoperative, 64.1; postoperative, 88.2) and International Knee Documentation Committee subjective (preoperative, 50.5; postoperative, 82.9) scores, were significantly improved (P < .001) 31.8 months postoperatively. Of the 61 patients who underwent second-look arthroscopy, 49 (80.3%) were classified into the complete healing group. There was no significant difference in postoperative PROs between the complete and partial healing groups.

CONCLUSION

The incidence of LMORT was 15.3% in patients with acute ACL injury, and type 4 LMORT was the most common type. Complete healing of LMORT was achieved in 80.3% of patients who underwent second-look arthroscopy, and the PROs were significantly improved postoperatively. Good clinical results can be achieved if the LMORT is repaired as much as possible during ACLR.

Tibiofemoral Contact Mechanics After Horizontal or Ripstop Suture in Inside-Out and Transtibial Repair for Meniscus Radial Tears in a Porcine Model

PURPOSE

To compare tibiofemoral contact mechanics after horizontal or ripstop (horizontal plus vertical) sutures in inside-out and transtibial repair for meniscal radial tears with 10 porcine knees in each group.

METHODS

Ten matched pairs of porcine knees were tested under a 1500-N axial compressive load at 0°, 30°, 60°, and 90° of knee flexion. Each knee underwent 4 testing conditions consecutively: (1) intact, (2) medial meniscal radial tear, (3) horizontal suture repair configuration, and (4) ripstop suture repair configuration. Tekscan sensors measured tibiofemoral contact pressure and contact area in the medial and lateral compartments.

RESULTS

All repair groups improved their contact mechanics when compared with the tear state among all flexion angles analyzed (all P < .05). Furthermore, ripstop sutures with both inside-out and transtibial repairs restored intact knee contact area and pressures (peak and mean) in the medial compartment at all flexion angles, whereas the horizontal sutures alone failed to do so for contact pressures at 60° and 90° and for contact surface areas at all flexion angles. However, the aforementioned parameters were not significantly different between inside-out sutures and transtibial sutures, regardless of horizontal or ripstop configuration (P > .05).

CONCLUSIONS

Radial tears of the meniscus in a porcine model significantly decreased medial contact area and increased mean and peak contact pressure. Both inside-out and transtibial ripstop repairs for radial tears aid in restoring intact tibiofemoral contact mechanics at all assessed knee flexion angles.

CLINICAL RELEVANCE

Our results suggest that both inside-out and transtibial ripstop repairs for radial tears can restore tibiofemoral contact mechanics to the intact state. Since the study were performed in an open fashion porcine model, the results should be carefully used in clinical practices, and the efficacy of the techniques through arthroscopic method should be further explored.

The Ratio of Tibial Slope and Meniscal Bone Angle for the Prediction of ACL Reconstruction Failure Risk

Background  A growing body of research is indicating that the tibial slope and the geometry of the tibiofemoral meniscal-cartilage interface may affect the risk of anterior cruciate ligament reconstruction (ACLR) failure. Increased lateral tibial posterior slope (LTPS) and reduced meniscal bone angle (MBA) are associated with increased risk of anterior cruciate ligament (ACL) injury. The significance of a LTPS-MBA ratio regarding the prediction of ACL failure risk remains unknown. As LTPS and MBA may eventually potentiate or neutralize each other, it is expected that a low LTPS-MBA ratio is associated with high chance of ACL graft survival while a high LTPS-MBA ratio is associated with high risk of ACL failure. Material and Methods  Out of 1,487 consecutive patients who underwent hamstring ACLR between August 2000 and May 2013, 54 ACLR failures with intact lateral menisci were included in this study and matched one-to-one with 54 control participants by age, sex, graft, surgical technique, and graft fixation method. Control participants had undergone ACLR without signs of lateral meniscal injury, graft failure, or insufficiency. MBA and LTPS were assessed on magnetic resonance imaging. Logistic regression was used to identify LTPS/MBA key cut-off ratios. Results  In this cohort, a LTPS-MBA ratio under 0.27 was associated with a 28% risk of ACLR failure (36% of patients), while a ratio exceeding 0.42 was associated with an 82% risk of ACLR failure (31% of patients). The odds of ACL failure increased by 22.3% per reduction of 1 degree in MBA (odds ratio [OR], 1.22; 95% limits, 1.1-1.34). No significant association was found between LTPS and the risk of ACL graft failure in transtibial ACLR, while the odds of ACL failure increased by 34.9% per degree of increasing LTPS in transportal ACLR (OR, 1.34; 95% limits, 1.01-1.79). No significant correlation was found between MBA and LTPS ( p  = 0.5). Conclusion  Reduced MBA was associated with significantly increased risk of ACL graft failure. A ratio of LTPS and MBA was found to be useful for the prediction of ACLR failure risk and may preoperatively help to identify patients at high risk of ACLR failure. This may have implications for patient counseling and the indication of additional extra-articular stabilizing procedures.

Evaluation of age-dependent morphometrics of the meniscofemoral ligaments in reference to the posterior cruciate ligament in routine MRI

OBJECTIVES

To quantify the morphological correlation between the posterior cruciate ligament (PCL) and the meniscofemoral ligaments (MFLs), to propose normal ranges for different age populations, and to define guidelines for correct identification and differentiation of MFLs in routine MRI.

METHODS

Three hundred forty-two subjects were included retrospectively and subdivided into five age groups. Morphometrics of the PCL and the MFLs were measured on standard MRI in the sagittal, coronal, and axial planes. Student's t test, Mann-Whitney U test, and ANOVA and Kruskal-Wallis tests with Bonferroni correction were used for comparison.

RESULTS

The MFLs did not vary significantly between sexes (p > 0.05) or in those older than 10 years (p > 0.05). Longitudinal MFL growth is completed before age 11 years, with cross-sectional area (CSA) increasing until age 20. The CSA of the PCL was significantly (p = 0.028) larger in knees without a pMFL (Mdn = 39.7 mm2) than with a pMFL (Mdn = 35.4 mm2). MFLs were more often detected on sagittal than coronal images.

CONCLUSIONS

This study describes the morphometric relation between the PCL and the MFLs on routine MRI. When reporting imaging findings in preparation for arthroscopic knee surgery, evaluation of MFLs, first in the sagittal and then the coronal plane, will achieve the best results.

KEY POINTS

• The MFLs and the PCL have distinct morphological patterns throughout life. • These patterns show intimate anatomical relationships and a potential biomechanical impact. • Those patterns and relationships can be quantified with MRI. • A correlation exists between age and morphometrics of the MFLs. • Recommendations for correct identification of the MFLs are provided.

Suture Repair of Full Radial Posterior Lateral Meniscus Tears Using a Central Midline Portal

Full radial posterior lateral meniscus root tears are frequently associated with injuries to the anterior cruciate ligament. Left unrepaired, they result in loss of the meniscus hoop stress function and can lead to overload of the lateral compartment and early degenerative changes. Arthroscopic suture repairs show successful results with long-term follow-up. However, previously described suture repair techniques have often required special instrumentation and can be technically demanding. This Technical Note describes the use of an accessory portal through the patellar tendon as a safe and easy method for repairing full posterior radial tears of the lateral meniscus.

Attachment area of fibres from the horns of lateral meniscus: anatomic study with special reference to the positional relationship of anterior cruciate ligament

PURPOSE

Although studies support the clinical importance of the fibres from the horns of lateral meniscus (LM), few studies have investigated the detailed anatomy. This anatomic study was conducted to analyse the structural details of LM with special reference to (1) the attachment area of the fibres from the anterior and posterior horns and (2) the positional relationship between these fibres and the anterior cruciate ligament (ACL).

METHODS

A total of 24 cadaveric knees were used in the macroscopic investigation, and six knees were used in the histological investigation. Micro-computed tomography analysis was also performed to assess the anatomy of the posteriormost fibre from the posterior horn of LM.

RESULTS

Based on the macroscopic investigations, the outer fibres from the anterior horn of LM extended to ACL and seemed to intermingle with ACL fibres. However, the histological investigations showed a distinct border between the fibres and ACL. The inner fibres from the anterior horn of LM attached to the lateral intercondylar tubercle serving as a lateral margin of ACL attachment. Fibres from the posterior horn of LM were separated into anterolateral and posteromedial crura which attached to the posterior aspect of the lateral and medial intercondylar tubercles, respectively. These two crura formed the posterior margin of the ACL attachment, except for the central part of ACL.

CONCLUSION

The outer fibres from the anterior horn of LM adjoined ACL. The inner fibres from the anterior horn of LM and two crura from the posterior horn of LM formed the border of the attachment area of ACL. The distinctive fibre anatomy from LM could provide a surgical landmark during arthroscopic surgery.

Are root avulsions of the lateral meniscus associated with extrusion at the time of acute anterior cruciate ligament injury?: a case control study

BACKGROUND

Lateral meniscal avulsions left in situ at the time of anterior cruciate ligament (ACL) reconstruction do well subjectively. Limited published results measure meniscal extrusion of the lateral compartment in this setting.

PURPOSE

To determine whether an avulsion of the posterior root of the lateral meniscus is associated with meniscal extrusion on magnetic resonance imaging (MRI).

STUDY DESIGN

Cohort study (prevalence); Level of evidence, 2.

METHODS

A prospective database of surgically treated ACL tears from 2007 to 2012 was reviewed. Isolated ACL tears without a concomitant injury were identified along with ACL tears in combination with lateral meniscal tears of the posterior root (PRLMTs). Thirty-five patients had ACL tears and PRLMTs verified arthroscopically, of which 23 patients had preoperative MRI scans available for review. From the same database, 25 isolated ACL tears with no meniscal injury were randomly chosen for comparison. Plain radiographs were reviewed for degenerative joint disease using the Kellgren-Lawrence scale. A board-certified radiologist blinded to arthroscopic findings reviewed each MRI scan using midcoronal sections to measure extrusion of the lateral meniscus. The average extrusion was calculated for each group and compared using a Student t test.

RESULTS

In the 48 patients reviewed, 1 patient was excluded because of a complex lateral meniscal tear that could not be measured on MRI. The remaining 47 consisted of 22 with root tears and 25 with intact menisci. None of these patients were noted to have degenerative joint disease greater than Kellgren-Lawrence grade 1. All of the patients with PRLMTs were noted to have intact meniscofemoral ligaments at the time of arthroscopic surgery. In the patients with ACL tears and PRLMTs, the average extrusion was 0.8 mm, and in the ACL tear group with an intact meniscus, the average extrusion measured 0.5 mm. No significant difference in the amount of extrusion was observed (P = .22).

CONCLUSION

At the time of acute ACL injuries, PRLMTs do not appear to result in meniscal extrusion on MRI.

Anatomical relationships between Wrisberg meniscofemoral and posterior cruciate ligament's femoral insertions

Objective

To evaluate the frequency and morphometry of the Wrisberg's ligament and its relationships with the posterior cruciate ligament's femoral insertion.

Study design

Controlled laboratory study.

Methods

24 unpaired knee pieces, 12 right and 12 left were submitted to a deep dissection of the Wrisberg and posterior cruciate ligaments. The pieces were photographed with a digital camera and ruler; the Image J software was used to measure the ligaments’ insertion areas, in square millimeters.

Results

The Wrisberg ligament was present in 91.6% of the studied pieces. In those its shape was elliptical in 12 pieces (54.54%). In 68% of the knees, the WL insertion was proximal to the medial intercondilar ridge, close to the PCL posteromedial bundle. The average area for the WL was 20.46 ± 6.12 mm². This number corresponded to 23.3% of the PCL's average area.

Conclusions

WL ligament is a common structure in knees. There is a wide variation of its insertion area. Proportionally to the PCL's insertion area the WL ones suggests that it may contribute to the posterior stability of the knee joint.

Comparison of medial and lateral meniscal transplantation with regard to extrusion of the allograft, and its correlation with clinical outcome

We compared extrusion of the allograft after medial and lateral meniscal allograft transplantation and examined the correlation between the extent of extrusion and the clinical outcome. A total of 73 lateral and 26 medial meniscus allografts were evaluated by MRI at a mean of 32 months (24 to 59) in 99 patients (67 men, 32 women) with a mean age of 35 years (21 to 52). The absolute values and the proportional widths of extruded menisci as a percentage were measured in coronal images that showed maximum extrusion. Functional assessments were performed using Lysholm scores. The mean extrusion was 4.7 mm (1.8 to 7.7) for lateral menisci and 2.9 mm (1.2 to 6.5) for medial menisci (p < 0.001), and the mean percentage extrusions were 52.0% (23.8% to 81.8%) and 31.2% (11.6% to 63.4%), respectively (p < 0.001). Mean Lysholm scores increased significantly from 49.0 (10 to 83) pre-operatively to 86.6 (33 to 99) at final follow-up for lateral menisci (p = 0.001) and from 50.9 (15 to 88) to 88.3 (32 to 100) for medial menisci (p < 0.001). The final mean Lysholm scores were similar in the two groups (p = 0.312). Furthermore, Lysholm scores were not found to be correlated with degree of extrusion (p = 0.242).

Thus, transplanted lateral menisci extrude more significantly than transplanted medial menisci. However, the clinical outcome after meniscal transplantation was not found to be adversely affected by extrusion of the allograft.

Repair of radial tears and posterior horn detachments of the lateral meniscus: minimum 2-year follow-up

PURPOSE

The aim of this study was to show that repair of posterior radial tears and horn detachments of the lateral meniscus is possible and to assess the outcomes.

METHODS

A retrospective review of 24 patients who had repair of a posterior defunctioning tear of the lateral meniscus combined with anterior cruciate ligament reconstruction was undertaken. Patients completed a follow-up postal questionnaire that included Lysholm, subjective International Knee Documentation Committee (IKDC), and Tegner scoring systems.

RESULTS

Eight patients had suture repair of a lateral meniscal radial tear. The mean Lysholm, IKDC, and Tegner scores were 86.9 (SD, 11.6), 81.6 (SD, 13.9), and 5.8 (SD, 2.7), respectively, at a mean follow-up of 70.5 months (range, 29.0 to 168.0 months). Subsequent arthroscopy in 2 patients confirmed meniscal healing. Sixteen patients underwent a posterior horn reattachment. The mean Lysholm, subjective IKDC, and Tegner scores were 86.1 (SD, 13.3), 84.3 (SD, 17.0), and 6.5 (SD, 2.1), respectively, at a mean follow-up of 53.6 months (range, 26.0 to 116.0 months). Three patients had subsequent magnetic resonance imaging and/or arthroscopy that indicated meniscal healing. Two further patients had reinjury, and magnetic resonance imaging and/or arthroscopy showed that their repairs had failed.

CONCLUSIONS

Posterior radial tears that extend to the capsule and posterior horn detachments of the lateral meniscus are frequently amenable to repair. In this study 22 of 24 repairs functioned successfully over a mean follow-up of 58.6 months (range, 26.0 to 168.0 months).

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

Results of arthroscopic all-inside repair for lateral meniscus root tear in patients undergoing concomitant anterior cruciate ligament reconstruction

PURPOSE

To evaluate the effectiveness of all-inside repair of posterior lateral meniscus root full-thickness tears with preoperative and postoperative magnetic resonance imaging (MRI) and to propose a system of classifying posterior lateral meniscus root tears.

METHODS

From June 2003 to March 2007, 27 (6.95%) of a consecutive series of 388 anterior cruciate ligament reconstructions had a concomitant posterior lateral meniscus root tear. Of the patients, 25 (92.6%) were followed up for a more than 1 year. There were 22 male and 3 female patients, with a mean age of 28.8 years. The mean timing of surgery after injury was 40.8 months. The preoperative and postoperative MRI scans were analyzed and compared. We classified posterior lateral meniscus root tears according to arthroscopic findings.

RESULTS

There was no postoperative effusion, joint-line tenderness, or positive McMurray provocation testing observed at the last follow-up. No statistically significant improvement was observed in the coronal plane in the 18 follow-up MRI scans (P = .096); however, sagittal extrusion improved significantly (P = .007). Posterior lateral meniscus root tears were classified based on arthroscopic findings: type I, oblique flap; type II, T shape; type III, longitudinal cleavage; or type IV, chronic inner loss. A type I tear was found in 7 patients, type II in 4, type III in 4, and type IV in 10.

CONCLUSIONS

After repair of posterior lateral meniscus root tears, MRI showed that the displaced lateral meniscus was reduced, mainly in the sagittal plane. Posterior lateral meniscus root tears were classified based on arthroscopic findings: type I, oblique flap; type II, T shape; type III, longitudinal cleavage; or type IV, chronic inner loss.

A biomechanical study of the meniscofemoral ligaments and their contribution to contact pressure reduction in the knee

The aim of this study was to test the hypothesis that the meniscofemoral ligaments (MFLs) of the human knee assist the lateral meniscal function in reducing tibiofemoral contact pressure. Five human cadaveric knee joints were loaded in axial compression in extension using a 4-degree of freedom rig in a universal materials testing machine. Contact pressures pre- and post-sectioning of the MFLs were measured using pressure sensitive film. Sectioning the MFLs increased the contact pressure significantly in the joints for two of the four measures. In addition to their known function in assisting the posterior cruciate ligament (PCL) to resist tibiofemoral posterior drawer, the MFLs also have a significant role in reducing contact stresses in the lateral compartment. Their retention in PCL and meniscal surgery is therefore to be advised.

The diagnostic accuracy of a clinical examination in determining intra-articular hip pain for potential hip arthroscopy candidates

PURPOSE

One purpose of this study was to determine whether signs and symptoms could identify when a majority of the hip pain was originating from intra-articular sources in potential arthroscopic surgery candidates. The second purpose was to quantify pain reduction after an anesthetic intra-articular injection in those with potential labral pathology.

METHODS

Subjects with hip pain being evaluated by an orthopaedic surgeon specializing in hip arthroscopy were prospectively enrolled in the study. Clinical examination results were recorded. Sensitivity, specificity, and likelihood ratios were calculated to determine their accuracy in identifying those who would have greater than 50% pain relief from those with 50% pain relief or less.

RESULTS

We enrolled 105 subjects in this study. An anesthetic intra-articular injection was performed in 49 potential candidates for arthroscopic surgery (47%). The mean age in these 49 subjects was 42 years (SD, 15 years; range, 18 to 68 years), with 25 men (51%) and 24 women (49%). According to magnetic resonance imaging (MRI) arthrogram, 18 individuals had a definite labral tear, 29 had a possible tear, and 2 had no labral tears. In those with definite tears or possible tears, 39% (n = 7) and 45% (n = 13), respectively, did not achieve a greater than 50% reduction of pain. Groin pain, clicking, pinching pain with sitting, lateral thigh pain, flexion abduction external rotation test, flexion-internal rotation-adduction test, and trochanteric tenderness were not useful in identifying those with greater than 50% pain relief from those with 50% relief or less.

CONCLUSIONS

The symptoms and signs investigated in this study did not accurately or consistently identify subjects with primary intra-articular pain sources. Furthermore, candidates for hip arthroscopy with a labral tear identified on MRI arthrogram had varied responses to anesthetic intra-articular injection. Therefore all labral tears identified on MRI arthrogram may not be a major contributor to patients' pain complaints, and medical personnel should look for other causes of pain.

LEVEL OF EVIDENCE

Level III, diagnostic study of nonconsecutive patients (without consistently applied gold standard).