Anatomy of the anterior root attachments of the medial and lateral menisci: a quantitative analysis

Effect of meniscus modelling assumptions in a static tibiofemoral finite element model: importance of geometry over material

Finite element studies of the tibiofemoral joint have increased use in research, with attention often placed on the material models. Few studies assess the effect of meniscus modelling assumptions in image-based models on contact mechanics outcomes. This work aimed to assess the effect of modelling assumptions of the meniscus on knee contact mechanics and meniscus kinematics. A sensitivity analysis was performed using three specimen-specific tibiofemoral models and one generic knee model. The assumptions in representing the meniscus attachment on the tibia (shape of the roots and position of the attachment), the material properties of the meniscus, the shape of the meniscus and the alignment of the joint were evaluated, creating 40 model instances. The values of material parameters for the meniscus and the position of the root attachment had a small influence on the total contact area but not on the meniscus displacement or the force balance between condyles. Using 3D shapes to represent the roots instead of springs had a large influence in meniscus displacement but not in knee contact area. Changes in meniscus shape and in knee alignment had a significantly larger influence on all outcomes of interest, with differences two to six times larger than those due to material properties. The sensitivity study demonstrated the importance of meniscus shape and knee alignment on meniscus kinematics and knee contact mechanics, both being more important than the material properties or the position of the roots. It also showed that differences between knees were large, suggesting that clinical interpretations of modelling studies using single geometries should be avoided.

Optimizing Socket-Tunnel Position for Meniscal Allograft Transplantation Combined With ACL Reconstruction: A 3D Model Analysis

Background

Socket-tunnel overlap during meniscal allograft transplantation (MAT) combined with anterior cruciate ligament reconstruction (ACLR) may compromise graft integrity and lead to impaired fixation and treatment failure.

Purpose/Hypothesis

The purpose of this study was to determine optimal socket-tunnel drilling parameters for medial and lateral MAT with concurrent ACLR using artificial tibias and computed tomography (CT) scans for 3-dimensional (3D) modeling. It was hypothesized that clinically relevant socket tunnels could be created to allow for concurrent medial or lateral MAT and ACLR without significant risk for overlap at varying tunnel guide angles.

Study Design

Descriptive laboratory study.

Methods

A total of 27 artificial right tibias (3 per subgroup) were allocated to 9 experimental groups based on the inclination of the socket tunnels (55°, 60°, and 65°) created for simulating medial and lateral MAT and ACLR. Five standardized socket tunnels were created for each tibia using arthroscopic guides: one for the ACL tibial insertion and one for each meniscus root insertion. CT scans were performed for all specimens and sequentially processed using computer software to produce 3D models for quantitative assessment of socket-tunnel overlap risk. Statistical analysis was performed with Kruskal-Wallis and Mann-Whitney U tests.

Results

No subgroup consistently presented significantly safer distances than other subgroups for all distances measured. Three cases (11%) and 24 cases (~90%) of tunnel overlap occurred between the ACL tunnel and tunnels for medial and lateral MAT, respectively. Most socket-tunnel overlap (25 of 27; 92.6%) occurred between sockets at depths ranging between 6.3 and 10 mm from the articular surface. For ACLR and posterior root of the lateral meniscus setting, the guide set at 65° increased socket-tunnel distances.

Conclusion

When combined ACLR and MAT using socket tunnels for graft fixation is performed, the highest risk for tibial socket-tunnel overlap involves the ACLR tibial socket and the lateral meniscus anterior root socket at a depth of 6 to 10 mm from the tibial articular surface.

Clinical Relevance

Setting tibial guides at 65° to the tibial articular surface with the tunnel entry point anteromedial and socket aperture location within the designated anatomic "footprint" will minimize the risk for socket-tunnel overlap.

Graft Suturing Method Affects on Graft Diameter in Hamstring-Based Anterior Cruciate Ligament Reconstruction

INTRODUCTION

 Various benefits of needleless suture loop techniques in anterior cruciate ligament reconstruction graft preparation have been discussed, yet their impact on graft diameter remains unexplored. We hypothesized that the suture loop technique would reduce the graft diameter compared to the conventional locking suture technique.

METHODS

 Fifty-seven patients whose grafts were made with the Krackow stitch (group K) and 54 patients with the suture loop (group SL) were analyzed retrospectively. (1) The distal (sutured side) diameter of each anteromedial bundle and posterolateral bundle was compared to the proximal (non-sutured side) diameter, and (2) the average of the proximal and distal graft diameters in each group was calculated.

RESULTS

 In group K, 78.9% of anteromedial bundles and 40.3% of posterolateral bundles exhibited a larger distal diameter than the proximal, while in group SL, 42.6% of anteromedial bundles and 3.7% of posterolateral bundles showed a larger distal diameter. In both bundles, there were significantly fewer grafts with larger distal diameters in group SL (p < 0.001). The mean distal diameter of anteromedial bundles was smaller in group SL (6.33 ± 0.43 mm vs. 6.07 ± 0.43 mm, p < 0.005). Consequently, the distal cross-sectional area of anteromedial bundles in group SL was 8% smaller than that in group K.

CONCLUSION

 The use of the suture loop technique resulted in a significantly smaller distal diameter of the anteromedial bundle. This reduces the size of the tibial tunnel and may contribute to a reduction in potential damage to adjacent structures.

Meniscus root tears: state of the art

BACKGROUND

Meniscus root tears represent significant pathology that, historically, has been underdiagnosed and undertreated. However, the recognition of their clinical and functional significance has recently surged, mainly due to their frequent association with anterior cruciate ligament injuries.

AIM

This comprehensive review discusses various aspects of meniscal root tears, including their epidemiology, biomechanics, etiology, clinical and radiological findings, classification, management and surgical techniques.

Medial Meniscus Posterior Root Repair Reduces but Does Not Avoid Histologic Progression of Osteoarthritis: Randomized In Vivo Experimental Study in a Rabbit Model

BACKGROUND

The optimal treatment option for meniscus root tears is still challenging, and whether the meniscus root repair ultimately can arrest or delay osteoarthritic changes is still a concern.

PURPOSE/HYPOTHESIS

The purpose of this study was 2-fold: (1) to describe and compare histopathologic findings of 3 different therapeutic options for medial meniscus posterior root tear: nonoperative management, partial meniscectomy, and meniscus root repair; and (2) to test the hypothesis that meniscus root tears treated nonoperatively predispose to a lower risk of osteoarthritic progression compared with partial meniscectomy.

STUDY DESIGN

Controlled laboratory study.

METHODS

Posteromedial meniscus root tears were carried out in 39 New Zealand White rabbits. Animals were randomly assigned into 3 experimental groups: partial meniscectomy after root tear (PM; n = 13), root tears treated conservatively (CT; n = 13), and transtibial root repair (RR; n = 13). Contralateral limbs were used as healthy controls. The animals were euthanized at 16 weeks postoperatively; tissue samples of femoral and tibial articular cartilage were collected and processed for macro- and microscopic assessment to detect signs of early osteoarthritis (OA). Each sample was histopathologically assessed using the Osteoarthritis Research Society International grading and staging system.

RESULTS

Osteoarthritic changes were the hallmark in all 3 experimental groups. The RR group had the lowest scores for cartilage damage (mean, 2.5; range, 2-3), and the PM group exhibited higher and more severe signs of OA (mean, 16; range, 9-16) compared with the CT group (mean, 5; range, 4-6). The between-group comparison revealed significant differences, as the PM group showed a significantly higher rate of macro- and microscopic osteoarthritic changes compared with the RR (P < .001) and CT (P < .001) groups. The weightbearing area of the medial femoral condyle was the most severely affected, and tidemark disruption was evident in all tissue samples.

CONCLUSION

Meniscus root repair cannot completely arrest the histopathologic progression of knee OA but leads to significantly less severe degenerative changes than partial meniscectomy and nonoperative treatment. Partial meniscectomy leads to the most severe osteoarthritic progression, while stable radial tears left in situ have lower progression compared with partial meniscectomy.

CLINICAL RELEVANCE

Histologic assessment is an essential tool and metric for guiding and understanding osteoarthritic features, providing insight into the disease development and progression. This study provides histopathologic evidence on osteoarthritic progression after medial meniscus posterior root repair. This knowledge can help to set more realistic expectations and can lead to the future development of augmented techniques.

Concurrent Repair of Medial Meniscal Ramp Lesions and Lateral Meniscus Root Tears in Patients Undergoing Anterior Cruciate Ligament Reconstruction: The "New Terrible Triad"

Recent studies have suggested that up to 8% of patients with anterior cruciate ligament (ACL) tears can present with a combined medial meniscal ramp lesion (MMRL) and lateral meniscus root tear (LMRT). MMRLs and LMRTs often are missed preoperatively and can increase the risk of ACL graft failure if left untreated. Given the potential synergistic biomechanical consequences and challenging repair techniques used for treatment, our group commonly refers to this presentation (MMRL-LMRT-ACL) as the "new terrible triad" of ACL pathology. This Technical Note aims to describe a systematic approach for arthroscopic assessment and our preferred inside-out and transtibial pull-out repair techniques to efficiently diagnose and treat a combined MMRL and LMRT at the time of ACL reconstruction surgery.

Clinical, Biomechanical, and Self-reported Health Status After ACL Reconstruction With Meniscal Repair in Soccer Players: Results at Minimum 1-Year Follow-up

Background

Performing meniscal repair with anterior cruciate ligament reconstruction (ACLR) has been shown to contribute to the long-term preservation of knee health and gait biomechanics.

Purpose

To evaluate the role of meniscal repair in the performance of semiprofessional soccer players who returned to sport after ACLR.

Study Design

Case series; Level of evidence, 4.

Methods

This study included 51 male soccer players (mean ± SD age, 28.82 ± 5.33 years) who underwent ACLR at a single institution between July 2018 and July 2019. The players were divided into 3 groups according to surgery type: ACLR only (n = 30), ACLR with lateral meniscal repair (n = 9), and ACLR with medial meniscal repair (n = 12). Outcomes were evaluated through clinical examination, self-reported health questionnaires (Cincinnati Knee Rating System, Tegner activity score, Tegner Lysholm Knee Scoring Scale, Tampa Scale of Kinesiophobia, and ACL-Return to Sport After Injury), and biomechanical performance evaluations (balance, strength, coordination, and symmetry tests). Parametric and nonparametric tests were carried out for multiple comparisons.

Results

The mean ± SD follow-up time was 20.75 ± 9.38 months. Although no significant differences emerged in clinical and self-reported health status, almost all the physical parameters tested resulted in lower performance in players treated with ACLR and meniscal repair. Moreover, patients with ACLR with lateral meniscal repair reported higher pain and fear of reinjury, with lower outcomes in terms of strength, symmetry, and coordination as compared with the other 2 groups. Balance abilities were significantly affected in players who underwent meniscal repair as compared with those who underwent ACLR only.

Conclusion

The findings showed that biomechanical performance measures and fear of reinjury were significantly worse in soccer players with associated meniscal repair at a minimum 1-year follow-up, especially in those with a lateral meniscal tear.

Knee MRI: Meniscus Roots, Ramps, Repairs, and Repercussions

Menisci play an essential role in maintaining normal pain-free function of the knee. While there are decades of MRI literature on the tears involving the meniscus body and horns, there is now a surge in knowledge regarding injuries at the meniscus roots and periphery. The authors briefly highlight new insights into meniscus anatomy and then summarize recent developments in the understanding of meniscus injuries that matter, emphasizing meniscus injuries at the root and peripheral (eg, ramp) regions that may be missed easily at MRI and arthroscopy. Root and ramp tears are important to diagnose because they may be amenable to repair. However, if these tears are left untreated, ongoing pain and accelerated cartilage degeneration may ensue. The posterior roots of the medial and lateral menisci are most commonly affected by injury, and each of these injuries is associated with distinctive clinical profiles, MRI findings, and tear patterns. Specific diagnostic pitfalls can make the roots challenging to evaluate, including MRI artifacts and anatomic variations. As with root tears, MRI interpretation and orthopedic treatment have important differences for injuries at the medial versus lateral meniscus (LM) periphery (located at or near the meniscocapsular junction). Medially, ramp lesions typically occur in the setting of an anterior cruciate ligament rupture and are generally classified into five patterns. Laterally, the meniscocapsular junction may be injured in association with tibial plateau fractures, but disruption of the popliteomeniscal fascicles may also result in a hypermobile LM. Updated knowledge of the meniscus root and ramp tears is crucial in optimizing diagnostic imaging before repair and understanding the clinical repercussions. ©RSNA, 2023 Online supplemental material is available for this article. Quiz questions for this article are available in the Online Learning Center.

Meniscal Extrusion: Diagnosis, Etiology, and Treatment Options

PURPOSE OF REVIEW

The concept of meniscal extrusion has recently been recognized as a hallmark of meniscus dysfunction. This review examines contemporary literature regarding the pathophysiology, classification, diagnosis, treatment, and future directions for investigation regarding meniscus extrusion.

RECENT FINDINGS

Meniscus extrusion, defined as >3 mm of radial displacement of the meniscus, leads to altered knee biomechanics and accelerated knee joint degeneration. Meniscus extrusion has been associated with degenerative joint disease, posterior root and radial meniscal tears, and acute trauma. Meniscus centralization and meniscotibial ligament repair have been proposed as techniques to address meniscal extrusion with promising biomechanical, animal model, and early clinical reports. Further studies on the epidemiology of meniscus extrusion and associated long-term nonoperative outcomes will help to elucidate its role in meniscus dysfunction and resultant arthritic development. Understanding and appreciation for the anatomic attachments of the meniscus will help to inform future repair techniques. Long-term reporting on the clinical outcomes of meniscus centralization techniques will yield insights into the clinical significance of meniscus extrusion correction.

A balance between native footprint coverage and overlap of the anterolateral meniscal root in tibial tunnel positioning during anterior cruciate ligament reconstruction: A 3D MRI study

BACKGROUND

Tibial footprint of anterior cruciate ligament (ACL) is situated close to the anterior lateral meniscal root (ALMR) attachment.

PURPOSE

To investigate the impact of the size and location of the tibial tunnel for ACL reconstruction on the ACL footprint coverage and overlap to the ALMR.

STUDY DESIGN

Controlled laboratory study.

METHODS

Twenty knee MRI scans from twenty healthy subjects were recruited, and three-dimensional (3D) tibia models were created to show the tibial attachment sites of ACL and ALMR. Surgical simulation of the tibial tunnel drilling was performed on each 3D model, entering the joint at an angle set at 60 degrees from the tibial plateau plane and 55 degrees from the posterior tibial condylar axis, with analysis for six different drill sizes; 7.5, 8, 8.5, 9, 9.5 and 10 mm; and nine locations; the center of the ACL attachment and eight locations 2% of the tibial width apart surrounding it. The width of the tibial plateau, the distance between ACL and ALMR attachment centers, and the size and location of the potential tibial tunnel were evaluated to determine association with the area of the ACL footprint coverage and ALMR overlap using a linear mixed effects model.

RESULTS

A large tunnel (p <.001), a central and anterior location (p <.029), and small tibial width (p =.015) were all associated with larger coverage of the ACL footprint. A large tunnel (p <.001), posteriorly and laterally located (p ≤ 0.001), and a small distance between the ACL and ALMR centers (p =.001) were significantly associated with a larger ALMR overlap. The association of the tunnel size to ALMR overlap reduced with a medial tunnel location.

CONCLUSIONS

The short distance between the centers of the ALMR attachment and native ACL footprint suggests that the ALMR will always be susceptible to overlap when the tibial tunnel is drilled in ACL reconstruction. Small alterations in tunnel location can lead to a statistically significant alteration with the amount of ALMR overlap. To minimize this overlap, whilst maintaining acceptable coverage of the ACL footprint, a tibial tunnel positioned in a medial or anteromedial location from the center of the ACL footprint is recommended.

Intra-Articular Mesenchymal Stem Cell Injection for Knee Osteoarthritis: Mechanisms and Clinical Evidence

Knee osteoarthritis presents higher incidences than other joints, with increased prevalence during aging. It is a progressive process and may eventually lead to disability. Mesenchymal stem cells (MSCs) are expected to repair damaged issues due to trilineage potential, trophic effects, and immunomodulatory properties of MSCs. Intra-articular MSC injection was reported to treat knee osteoarthritis in many studies. This review focuses on several issues of intra-articular MSC injection for knee osteoarthritis, including doses of MSCs applied for injection and the possibility of cartilage regeneration following MSC injection. Intra-articular MSC injection induced hyaline-like cartilage regeneration, which could be seen by arthroscopy in several studies. Additionally, anatomical, biomechanical, and biochemical changes during aging and other causes participate in the development of knee osteoarthritis. Conversely, appropriate intervention based on these anatomical, biomechanical, biochemical, and functional properties and their interactions may postpone the progress of knee OA and facilitate cartilage repair induced by MSC injection. Hence, post-injection rehabilitation programs and related mechanisms are discussed.

Early ACLR and Risk and Timing of Secondary Meniscal Injury Compared With Delayed ACLR or Nonoperative Treatment: A Time-to-Event Analysis Using Machine Learning

BACKGROUND

Surgical and nonoperative management of anterior cruciate ligament (ACL) injuries seek to mitigate the risk of knee instability and secondary meniscal injury. However, the associated risk and timing of secondary meniscal tears have not been completely elucidated.

PURPOSE

To compare risk and timing of secondary meniscal injury between patients receiving nonoperative management, delayed ACL reconstruction (ACLR), and early ACLR using a machine learning survival analysis.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

A geographic database was used to identify and review records of patients with a diagnosis of ACL rupture between 1990 and 2016 with minimum 2-year follow-up. Patients undergoing ACLR were matched 1:1 with nonoperatively treated controls. Rate and time to secondary meniscal tear were compared using random survival forest algorithms; independent models were developed and internally validated for predicting injury-free duration in both cohorts. Performance was measured using out-of-bag c-statistic, calibration, and Brier score. Model interpretability was enhanced using global variable importance and partial dependence curves.

RESULTS

The study included 1369 patients who underwent ACLR and 294 patients who had nonoperative treatment. After matching, no significant differences in rates of secondary meniscal tear were found (P = .09); subgroup analysis revealed the shortest periods of meniscal survival in patients undergoing delayed ACLR. The random survival forest algorithm achieved excellent predictive performance for the ACLR cohort, with an out-of-bag c-statistic of 0.80 and a Brier score of 0.11. Significant variables for risk of meniscal tear for the ACLR cohort included time to return to sports or activity ≤350 days, time to surgery ≥50 days, age at injury ≤40 years, and high-impact or rotational landing sports, whereas those in the nonoperative cohort model included time to RTS ≤200 days, visual analog scale pain score >3 at consultation, hypermobility, and noncontact sports.

CONCLUSION

Delayed ACLR demonstrated the greatest long-term risk of meniscal injury compared with nonoperative treatment or early ACLR. Risk factors for decreased meniscal survival after ACLR included increased time to surgery, shorter time to return to sports or activity, older age at injury, and involvement in high-impact or rotational landing sports. Pending careful external validation, these models may be deployed in the clinical space to provide real-time insights and enhance decision making.

Review of Meniscus Anatomy and Biomechanics

PURPOSE OF REVIEW

Anatomic repair of meniscal pathology is critical for restoring native joint biomechanics and kinematics for patients who suffer from meniscal tears. The purpose of this review was to summarize the pertinent anatomy, biomechanics, and kinematics of the meniscus to guide surgeons during meniscal repair procedures.

RECENT FINDINGS

Over the past decade, there has been a growing trend to save the meniscus whenever possible. The goal of repair should be to recreate native anatomy as close as possible to recapitulate normal mechanics. Studies describing the quantitative and qualitative relationship of the meniscus roots, ligaments, and attachments are key in guiding any meniscus repair. This review summarizes these relationships, with particular emphasis on meniscal roots and other key attachments to the meniscus. The composition, embryology, vascularization, biomechanics, in vivo kinetics, and in vivo kinematics of the meniscus are also discussed in this review. Meniscal tears can cause profound functional, biomechanical, and kinematic derangements within the knee joint leading to accelerated degeneration of the articular cartilage. A strong understanding of the quantitative and qualitative relationships of the meniscus and its attachments with key arthroscopic landmarks will allow a surgeon to anatomically repair meniscal pathology in order to restore native joint biomechanics.

Correlation Between Anatomic Landmarks and Bony Trough Position in Lateral Meniscal Allograft Transplant

Background

Determining the rotational axis of the bony trough during lateral meniscal allograft transplant (MAT) is difficult. The use of anatomic landmarks may help a surgeon determine the rotational alignment of the graft during the procedure.

Purpose

To investigate the association between the knee's anatomic landmarks and the position of the bony trough to prevent extrusion after lateral MAT.

Study Design

Cross-sectional study; Level of evidence, 3.

Methods

Enrolled were 44 patients who underwent lateral MAT between July 2000 and February 2011. The patients' mean age at the time of surgery was 30.8 years. Extrusion was measured on magnetic resonance imaging (MRI) scans at a mean of 3.6 months postoperatively, and patients were divided into an extrusion group (n = 15) and a no-extrusion group (n = 29). Three coronal MRI scans from each patient were selected, each from the region at the level of the tibial tuberosity (TT), the anterior bony trough, and the posterior bony trough. We measured the distance between the center of the anterior bony trough and the center of the TT (the TT distance) and the distance between the center of the posterior bony trough and the medial border of the lateral femoral condyle (LFC) (the LFC distance).

Results

The mean center of the anterior bony trough was in a more medial position relative to the center of the TT in the no-extrusion group (-2.9 ± 4.8 mm) compared with the extrusion group (1.3 ± 4.9 mm; P = .010). The mean center of the posterior bony trough was in a more medial position relative to the medial border of the LFC in the no-extrusion group (-1.7 ± 3.9 mm) compared with the extrusion group (1.0 ± 3.2 mm; P = .027). Both TT distance and LFC distance were significantly correlated with extrusion (P = .005 and .025, respectively). The cutoff value was -0.24 mm for the anterior bony trough and -0.58 mm for the posterior bony trough (negative values indicate that the trough was medial to the respective landmarks).

Conclusion

To prevent extrusion of the allograft, the center of the anterior bony trough needs to be aligned with the center of the TT, and the center of the posterior bony trough needs to be aligned with the medial border of the LFC.

An anatomical study of the meniscal roots of the knee: landmarks for its surgical reconstruction and implications for knee surgeons

PURPOSE

The aim of this anatomical study was to describe the anatomy of the meniscal roots and their relationships with respect to the main adjacent structures in order to improve their surgical reconstruction.

METHODS

Fourteen knees were included. The mean age of the donors was 92 years (range 89-96). We studied the general characteristics of the anterior and posterior roots of the medial meniscus and lateral meniscus by measuring their widths at their base and area. We investigated the relations between anterior and posterior roots of the medial and lateral menisci with respect to the anterior and posterior cruciate ligaments (ACL and PCL).

RESULTS

The mean width of the anterior root of the lateral meniscus was 10.5 ± 1.4 mm. The mean width of the anterior root of the medial meniscus was 10 ± 1.5 mm. The mean width of the posterior root of lateral meniscus was 11.4 ± 1.4 mm. The mean width of the posterior root of medial meniscus was 10.5 ± 1.0 mm. The mean distance between the anterior cruciate ligament and the anterior root of lateral meniscus was 9.8 ± 2.9 mm, for the medial meniscus it was 15.9 ± 3.4 mm. The mean distance between the posterior cruciate ligament and the posterior root of the lateral meniscus was 11.5 ± 2.7 mm, for the medial meniscus, it was 11 ± 2.6 mm.

CONCLUSION

The anterior and posterior meniscal roots have precise landmarks, and this article contributes to define the location of the meniscal roots with respect to their adjacent anatomical structures: ACL, PCL and intercondylar tubercle. Having precise measures of the distances between the meniscus roots and these structures allows knee surgeons to perform ACL reconstruction, meniscal root repair and meniscal allograft transplantation.

A newly-developed guide can create tibial tunnel at an optimal position during medial meniscus posterior root repairs

BACKGROUND

During transtibial pullout repair of medial meniscus (MM) posterior root tears (MMPRTs), accurate tibial tunnel creation within the anatomic MM posterior root attachment seems critical. This study aimed to evaluate the tibial tunnel position created by a newly-developed Precision guide during pullout repair of MMPRTs.

METHODS

In 40 patients who underwent transtibial pullout repairs, the tibial tunnel was created using the Unicorn Meniscal Root (UMR) (n = 20) or Precision guide (n = 20). Three-dimensional computed tomography images of the tibial surface were evaluated postoperatively, using Tsukada's measurement method. The expected anatomic center of the MM posterior root attachment was defined as the center of three tangential lines corresponding to anatomic bony landmarks. The expected anatomic center (AC) and the tibial tunnel center (TC) were evaluated using the percentage-based posterolateral location on the tibial surface. The difference in the mediolateral and anteroposterior percentage distance between the AC and TC was calculated, as was the absolute distance between the AC and TC.

RESULTS

The mean AC was located 77.4% posterior and 40.1% lateral. The mean TC was similar in the UMR and Precision guide groups. There was no significant difference in the mediolateral percentage distance (UMR 3.9% vs. Precision 3.6%, p = 0.405), but a significant difference was observed in the anteroposterior percentage distance (UMR 3.5% vs. Precision 2.6%, p = 0.031). The mean absolute distance between the AC and TC was 3.9 mm and 3.5 mm (UMR and Precision guide groups, respectively) (p = 0.364).

CONCLUSIONS

The new Precision guide can create tibial tunnel in an optimal and stable position during pullout repair of MMPRTs.

Posterior-Medial Meniscal Root Repair Through Lateral Tibial Tunnel Combined With Medial Opening Osteotomy and Homologous Graft

When there is a rupture in the meniscal roots or close to them, the menisci suddenly and considerably reduce their capacity to absorb the axial mechanical load that passes through the knee, quickly leading to the development of a process of chondral degeneration. The varus deformity of the lower limb (when the mechanical axis crosses the medial compartment of the knee) favors this type of injury owing to the overload in the medial compartment. When the patient has both varus deformity and medial meniscal posterior root injury, there is a clear indication for surgical realignment of the affected lower limb. There is still not a consensus regarding combining meniscal root repair with corrective osteotomy, although there is a tendency to perform both procedures aiming at long-term joint preservation. We present a safe alternative technique for simultaneous medial meniscal posterior root repair using a lateral tibial transosseous tunnel associated with a valgus-producing high tibial osteotomy with homologous bone grafting, allowing a full return to daily activities and sports.

Accuracy of the Arthroscopic Location of the Center of the Anterior Horn During Lateral Meniscal Allograft Transplantation

Background

Anatomic placement of the meniscal allograft is imperative to achieve satisfactory outcomes after meniscal allograft transplantation (MAT). Few studies have reported on the accuracy of the provisional location of the center of the anterior horn of the lateral meniscus (AHLM).

Hypothesis

The authors hypothesized that the provisional center would not coincide with the anatomic center of the AHLM.

Study Design

Descriptive laboratory study.

Methods

Tibial plateaus were retrieved from 93 consecutive patients who underwent total knee arthroplasty. A complete radial cut was made 2 cm lateral to the insertion of the AHLM on the retrieved tibial plateau. While moving the stump of the anterior horn with forceps, the center of the insertion was determined, and a Kirschner wire (provisional wire) was drilled into the location. The insertion area of the AHLM was dissected carefully, and the periphery of the insertion area of the anterior horn was marked. Another Kirschner wire (anatomic wire) was drilled into the center of the dissected anterior horn. The resected tibial plateau was positioned so that the longitudinal line of the tibial plateau was aligned on a plastic ruler. The distance between the provisional and anatomic wires was measured by a digital caliper along the longitudinal and vertical axes.

Results

The mean distance between the provisional and anatomic wires was 2.5 ± 1.2 mm. The provisional wire in 14 patients (15%) was placed at the anatomic center. In 36 patients (39%), the provisional wire was drilled anterolateral to the anatomic center, and in 18 patients (19%), the wire was drilled anteromedial to the anatomic center. In 21 patients (23%), the provisional wire was located within 2 mm of the anatomic center, and in 62 patients (67%), the wire was located within 3 mm of the anatomic center.

Conclusion

The provisional wire was located a mean of 2.5 mm from the anatomic center, and only 23% of patients had wires that were located within 2 mm of the anatomic center. In 39% of patients, the provisional wire was drilled anterolateral to the anatomic center. This finding needs to be considered during lateral MAT.

Clinical Relevance

Without dissection of the AHLM, the determination of the anatomic center of the anterior horn is not accurate during lateral MAT.

Current Reviews in Musculoskeletal Medicine: Current Controversies for Treatment of Meniscus Root Tears

PURPOSE OF REVIEW

The role of the meniscus in preserving the biomechanical function of the knee joint has been clearly defined. The hypothesis that meniscus root integrity is a prerequisite for meniscus function is supported by the development of progressive knee osteoarthritis (OA) following meniscus root tears (MRTs) treated either non-operatively or with meniscectomy. Consequently, there has been a resurgence of interest in the diagnosis and treatment of MRTs. This review examines the contemporary literature surrounding the natural history, clinical presentation, evaluation, preferred surgical repair technique and outcomes.

RECENT FINDINGS

Surgeons must have a high index of suspicion in order to diagnose a MRT because of the nonspecific clinical presentation and difficult visualization on imaging. Compared with medial MRTs that commonly occur in middle age/older patients, lateral meniscus root injuries tend to occur in younger males with lower BMIs, less cartilage degeneration, and with concomitant ligament injury. Subchondral insufficiency fractures of the knee have been found to be associated with both MRTs and following arthroscopic procedures. Meniscus root repair has demonstrated good outcomes, and acute injuries with intact cartilage should be repaired. Cartilage degeneration, BMI, and malalignment are important considerations when choosing surgical candidates. Meniscus centralization has emerged as a viable adjunct strategy aimed at correcting meniscus extrusion. Meniscus root repair results in a decreased rate of OA and arthroplasty and is economically advantageous when compared with nonoperative treatment and partial meniscectomy. The transtibial pull-through technique with the addition of centralization for the medial meniscus is associated with encouraging early results.

The Natural History of Medial Meniscal Root Tears: A Biomechanical and Clinical Case Perspective

Posterior medial meniscus root tears (PMMRTs) make up a relatively notable proportion of all meniscus pathology and have been definitively linked to the progression of osteoarthritis (OA). While known risk factors for development of OA in the knee include abnormal tibial coronal alignment, obesity and female gender, PMMRTs have emerged in recent years as another significant driver of degenerative disease. These injuries lead to an increase in average contact pressure in the medial compartment, along with increases in peak contact pressure and a decrease in contact area relative to the intact state. Loss of the root attachment impairs the function of the entire meniscus and leads to meniscal extrusion, thus impairing the force-dissipating role of the meniscus. Anatomic meniscus root repairs with a transtibial pullout technique have been shown biomechanically to restore mean and peak contact pressures in the medial compartment. However, nonanatomic root repairs have been reported to be ineffective at restoring joint pressures back to normal. Meniscal extrusion is often a consequence of nonanatomic repair and is correlated with progression of OA. In this study, the authors will describe the biomechanical basis of the natural history of medial meniscal root tears and will support the biomechanical studies with a case series including patients that either underwent non-operative treatment (5 patients) or non-anatomic repair of their medial meniscal root tears (6 patients). Using measurements derived from axial MRI, the authors will detail the distance from native root attachment center of the non-anatomic tunnels and discuss the ongoing symptoms of those patients. Imaging and OA progression among patients who were treated nonoperatively before presentation to the authors will be discussed as well. The case series thus presented will illustrate the natural history of meniscal root tears, the consequences of non-anatomic repair, and the findings of symptomatic meniscal extrusion associated with a non-anatomic repair position of the meniscus.

Meniscus Anatomy and Basic Science

A basic understanding of meniscal anatomy and biomechanics is important for physicians evaluating knee injuries and surgeons treating meniscal injuries. This chapter provides a concise review of meniscal anatomy and biomechanics relevant for the evaluation and treatment of meniscus injuries. Anatomic landmarks relevant for meniscal root repair and transplant are discussed, along with the gross, microscopic, vascular, and neuroanatomy of the menisci.

Case Report: Anterior Cruciate Ligament Calcification in a Patient With Chondrocalcinosis: Micro-Computed Tomography Presentation

In this case report, an incidental postoperative diagnosis of anterior cruciate ligament (ACL) calcification, associated with calcification of posterior cruciate ligament (PCL) and lateral meniscus insertions, was made using micro-computed tomography (μCT) technology in a knee specimen obtained during a total knee replacement (TKR) surgery due to painful tri-compartmental osteoarthritis (OA) with chondrocalcinosis signs at preoperative X-ray. Anterior cruciate ligament calcification is an uncommon finding, and conventional X-ray and MRI are not so helpful in its identification. μCT scan, in contrast, is of interest because it provides highly spatial three-dimensional information with excellent visualization of bones and calcifications. The μCT technology used in this case report allowed us to perform a detailed analysis and a 3-D reconstruction of the calcium pyrophosphate dihydrate (CPPD) crystal deposition about the knee without the need to section the specimens into slice as performed in previous studies. The 3-D model obtained with μCT scan permits to gain more insight into the shape of the calcification within the fibers of the ligamentous structures of the joint.

Meniscal Root Repair Along with Auxiliary Procedures for Joint Preservation: Current Concepts

Meniscal root repair and joint preservation surgeries have gained increased interest in the last decade, from a better interpretation of the role of meniscal functions, from the biomechanical studies. Several published results from both biomechanical and clinical studies has proven the effectiveness of meniscal root repairs and has led to a unanimous international consensus for the need for root repair surgery. Meniscal repair by suture pull-out technique is widely followed around the world and leads to adequate healing and good clinical outcome. There are auxiliary procedures like centralization sutures (to reduce the meniscal extrusion), high tibial osteotomy, cartilage repair procedures, meniscal root reconstruction and ligament reconstructions are performed along with meniscal root repair, especially in the younger patients and recently sub-chondroplasty for the bone marrow lesions (BMLs) are also executed. This review article discusses the anatomy, types of root tears, evaluation, treatment, outcomes of root repair, and the need for additional procedures, which are imperative for joint preservation and restoration of the biomechanics of the knee.

Effect of Percentage of Femoral Anterior Cruciate Ligament Insertion Site Reconstructed With Hamstring Tendon on Knee Kinematics and Graft Force

BACKGROUND

Previous studies have stated that closely matching the size of the anterior cruciate ligament (ACL) insertion site footprint is important for biomechanical function and clinical stability after ACL reconstruction. However, the ACL varies widely regarding the area of femoral insertion, tibial insertion, and midsubstance of ACL, and reconstructing the insertion site area with a uniform diameter graft can result in a cross-sectional area that is greater than that of the midsubstance of the native ACL. Therefore, understanding the effect of relative graft size in ACL reconstruction on knee biomechanics is important for surgical planning.

PURPOSE

To assess how the percentage of femoral insertion site affects knee biomechanics in single- and double-bundle ACL reconstruction.

STUDY DESIGN

Controlled laboratory study.

METHODS

A total of 14 human cadaveric knees were scanned with magnetic resonance imaging and tested using a robotic system under an anterior tibial load and a combined rotational load. In total, 7 knee states were evaluated: intact ACL; deficient ACL; single-bundle ACL reconstruction with approximate graft sizes 25% (small), 50% (medium), and 75% (large) of the femoral insertion site; and double-bundle reconstruction of approximately 50% (medium) and 75% (large) of the femoral insertion site, based on the ratio of the cross-sectional area of the graft to the area of the femoral ACL insertion site determined by magnetic resonance imaging.

RESULTS

Anterior tibial translation was not significantly larger than the intact state in single-bundle and double-bundle medium graft reconstructions (P > .05) and was significantly greater in the single-bundle small graft reconstruction (P < .05). Anterior knee translation in single-bundle medium graft and large graft reconstructions was not statistically different (P > .05). In contrast, the anterior tibial translation for double-bundle large graft reconstruction was significantly smaller than for double-bundle medium graft reconstruction at low flexion angles (P < .05). The single-bundle small graft force was significantly different from the intact ACL in situ force (P < .05). The graft force with double-bundle large reconstruction was significantly greater than that with the double-bundle medium reconstruction (P < .05) but was not significantly different from that of the intact ACL (P > .05).

CONCLUSION

Knee biomechanics with a single-bundle small graft tended to be significantly different from those of the intact knee. In the kinematic and kinetic data for the single- and double-bundle medium graft reconstruction, only the anterior translation at full extension for the single-bundle reconstruction was significantly different (lower) from that of intact knee. This was a time zero study.

CLINICAL RELEVANCE

This study can provide surgeons with guidance in selecting the graft size for ACL reconstruction.

Anterior root of lateral meniscus and medial tibial spine are reliable intraoperative landmarks for the tibial footprint of anterior cruciate ligament

PURPOSE

The aims of the present study were (1) to investigate the tibial footprint location of the anterior cruciate ligament (ACL) in both ACL-ruptured and ACL-intact patients, (2) to identify the relationship of the tibial footprint to the anterior root of the lateral meniscus (ARLM) and medial tibial spine (MTS), and (3) to evaluate the reliability of the ARLM and MTS for identifying the center of the tibial ACL footprint.

METHODS

Magnetic resonance images of 90 knees with ACL rupture and 90 matched-controlled knees were used to create three-dimensional models of the tibia. The tibial ACL footprint was outlined on each model, and its location was measured using an anatomical coordinate system.

RESULTS

No significant difference in the location of the tibial footprint was found between ACL-ruptured and ACL-intact knees. The tibial ACL footprint was located in very close proximity to the ARLM, especially in the M/L direction. The safe zone of tibial tunnel reaming for avoiding damage to the ARLM was 2.6 mm lateral to the center of the native tibial footprint. Both the ARLM and MTS were reliable intraoperative landmarks for identifying the tibial footprint.

CONCLUSIONS

Orthopedic surgeons should be aware of the safe zone of tibial tunnel reaming for avoiding injury to the ARLM. Both the ARLM and MTS might be reliable landmarks for identifying the center of the tibial ACL footprint and may facilitate tibial tunnel placement during anatomical single-bundle ACL reconstruction, especially in cases of revision where the tibial ACL stump is not available.

LEVEL OF EVIDENCE

Level III.

Partial lateral meniscus anterior root injuries during anatomical single-bundle anterior cruciate ligament reconstruction are likely to occur in women with small skeletons

PURPOSE

This study aimed to investigate the occurrence and characteristics of lateral meniscus anterior root injuries during anatomical single-bundle anterior cruciate ligament (ACL) reconstruction.

METHODS

Between 2011 and 2018, 70 women who had ACL injuries without lateral meniscal tears underwent anatomical single-bundle ACL reconstruction. Using computed tomography, the anatomical relationship between the predicted lateral meniscus anterior root insertion and the tibial tunnel was retrospectively assessed, and the patients were divided into partial lateral meniscus anterior root injury and intact groups. The demographic characteristics, the distances between bony landmarks, the tibial tunnel sizes, and lateral meniscal extrusion assessed by magnetic resonance imaging were compared between the two groups.

RESULTS

Thirteen of the 70 patients had suspected partial lateral meniscus anterior root injuries. Patient height was significantly shorter in the injury group than in the intact group (157.7 ± 6.4 vs. 161.4 ± 5.4 cm: p = 0.03); the distance from the apex to the bottom of the slope of the medial intercondylar ridge was significantly shorter in the injury group than in the intact group (15.1 ± 1.9 vs. 16.7 ± 1.4 mm: p = 0.001).

CONCLUSIONS

Partial lateral meniscus anterior root injury during anatomical single-bundle ACL reconstruction was suspected in 18% of cases. Patient height and the distance between bony landmarks were significantly shorter in the injury group than in the intact group. Surgeons should understand that even a slight deviation of the tibial tunnel position can lead to partial lateral meniscus anterior root injury in patients with small skeletons.

LEVEL OF EVIDENCE

IV.

Medial meniscus posterior root tear causes swelling of the medial meniscus and expansion of the extruded meniscus: a comparative analysis between 2D and 3D MRI

PURPOSE

This study aimed to clarify the advantages of three-dimensional (3D) magnetic resonance imaging (MRI) over two-dimensional (2D) MRI in measuring the size of the medial meniscus (MM) and to analyse the volumes of MM and the extruded meniscus in patients with MM posterior root tear (MMPRT), at 10° and 90° knee flexion.

METHODS

This study included 17 patients with MMPRTs and 15 volunteers with uninjured knees. The MMs were manually segmented for 3D reconstruction; thereafter, the extruded part separated from the tibial edge was determined. The length, width, height, and extrusion of MM were measured by the 2D and 3D methods, and compared. The MM volume, extruded meniscus volume, and their ratio were also calculated using 3D analysis software in the two groups.

RESULTS

The estimated length and posterior height of MM were larger with 3D MRI than with 2D MRI measurements. The MM volume was significantly greater in MMPRT knees than in normal knees, with increasing MM height. In MMPRT knees, the mean volume of the extruded meniscus and its ratio significantly increased by 304 mm³ (p = 0.02) and 9.1% (p < 0.01), respectively, during knee flexion.

CONCLUSIONS

This study demonstrated that 3D MRI could estimate the precise MM size and that MMPRT caused swelling of the meniscus due to the increased thickness in the posteromedial part. The clinical significance of this study lies in its 3D evaluation of MM volume, which should help the surgeon understand the biomechanical failure of MM function and improve MMPRT repair technique.

LEVEL OF EVIDENCE

III.

Medial meniscus posterior root repair restores the intra-articular volume of the medial meniscus by decreasing posteromedial extrusion at knee flexion

PURPOSE

Transtibial repair of a medial meniscus posterior root tear (MMPRT) can improve clinical outcomes, although meniscal extrusion remains. However, few studies have investigated the volume of meniscal extrusion. This study aimed to evaluate the effect of transtibial repair in reducing the volume using three-dimensional (3D) magnetic resonance imaging, at 10° and 90° knee flexion.

METHODS

Twenty patients with MMPRTs and 16 volunteers with normal knees participated. The 3D models of meniscus were constructed using SYNAPSE VINCENT^®. The meniscal extrusion and its volume were measured at 10° and 90° knee flexion. Differences between the pre- and postoperative examinations were assessed using the Wilcoxon signed-rank test. The postoperative parameters were compared to those in patients with normal knees.

RESULTS

There were no significant pre- and postoperative differences in any parameter at 10° knee flexion. At 90° knee flexion, the posterior extrusion and its meniscal volume were decreased significantly after transtibial repair (p < 0.05), even though these parameters were larger than in the normal knees. On the other hand, intra-articular meniscal volume calculated by the extrusion volume was increased to the level of the normal knee.

CONCLUSIONS

This study demonstrated that transtibial repairs improved the intra-articular/intra-tibial surface volume of the medial meniscus by reducing the posteromedial extrusion during knee flexion. This 3D analysis is clinically relevant in evaluating that, while transtibial root repair has a limited ability to reduce meniscal extrusion, it can restore the functional volume of the medial meniscus which contributes to the shock absorber postoperatively.

LEVEL OF EVIDENCE

IV.

A histological study of the medial meniscus posterior root tibial insertion

Purpose/Aim of the study: Posterior root injury of the medial meniscus often leads to articular cartilage degeneration due to altered biomechanics. To avoid dysfunction, the attachment must be repaired using the transtibial pullout technique. To guide appropriate placement of the tibial tunnel, additional details on the normal anatomy of the meniscus insertion are needed. Therefore, we performed a histological analysis of a tibial bone slice with the medial meniscus posterior insertion obtained during total knee arthroplasty surgery. Materials and methods: Horizontal slices of the proximal tibia were obtained from 7 patients with osteoarthritis who underwent total knee arthroplasty. After decalcification, the region of the posterior horn was cut out and segmented into four pieces (2.0 mm thickness; medial to lateral). Sagittal sections were evaluated by safranin O staining or immunohistochemistry with anti-type collagen antibody. Results: Safranin O staining showed that the insertion of the posterior root consisted primarily of fibrocartilaginous layers in segment 2. Anatomically, segment 2 corresponded to the sagittal plane passing through the peak of the medial intercondylar tubercle. In this section, safranin O staining and immunohistochemistry revealed that the anterior one-third of the posterior root insertion was richer in proteoglycans and type II collagen than the central and posterior one-third. Conclusions: Anatomical insertion of the posterior root of the medial meniscus was located at the sagittal plane passing through the peak of the medial intercondylar tubercle. The structure of the medial meniscus posterior insertion was mainly localized in the anterior one-third.

Nonanatomic Placement of Posteromedial Meniscal Root Repairs: A Finite Element Study

Nonanatomic placement of posteromedial meniscal root repairs alters knee mechanics; however, little is known about how the position and magnitude of misplacement affect knee mechanics. Finite element knee models were developed to assess changes in cartilage and meniscus mechanics for anatomic and various nonanatomic repairs with respect to intact. In total, 25 different repair locations were assessed at loads of 500 N and 1000 N. The two-simple-suture method was represented within the models to simulate posteromedial meniscal root repairs. Anatomic repairs nearly restored total contact area; however, meniscal hoop stress decreased, meniscal extrusion increased, and cartilage-cartilage contact area increased. Repairs positioned further posterior altered knee mechanics the most and repairs positioned further anterior restored knee mechanics for posteromedial root repairs. Despite this, repair tension increased with further anterior placement. Anterior placement of repairs results in more restorative contact mechanics than posterior placement; however, anterior placement also increased the risk of suture cut-out or failure following repairs. Anatomic placement of repairs remains the best option because of the risks involved with anterior placement; however, suture methods need to be improved to better restore the strength of repairs to that of the native insertion. Proper placement of repairs is important to consider with meniscal root repairs because misplacement may negatively affect cartilage and meniscus mechanics in patients.

Medial Meniscus Root Repair in Patients With Open Physes

Meniscal root tears have become increasingly recognized in the past decade. Lateral meniscus root tears typically occur in active, younger patients who sustain acute anterior cruciate ligament tears. Conversely, medial meniscus root tears typically occur in isolation and affect middle-aged patients. However, recent reports have described the incidence of meniscal root tears occurring in pediatric populations who are skeletally immature. The purpose of this technical note is to describe the authors' surgical technique for medial meniscal root repair for patients with open physes.

Meniscal Root Injuries

Meniscal root tears are an increasingly recognized injury leading to notable functional limitations, potential rapid cartilage deterioration of the affected compartment, and subsequent risk of total knee arthroplasty if left untreated. Repair of these tears is advised when articular cartilage remains intact because both medial and lateral meniscus root repairs have demonstrated favorable results. Recent literature demonstrates decreased rates of osteoarthritis and arthroplasty after medial meniscus root repair compared with partial meniscectomy and nonsurgical management. The transtibial pull-out repair technique is most commonly used and provides a biomechanically strong suture construct with standard and familiar knee arthroscopy portals. Furthermore, repair has recently been shown to be economically effective by decreasing overall societal healthcare costs when compared with more conservative management strategies. This review outlines the evaluation, treatment, and documented outcomes of meniscal root repair, which is imperative to the preservation of knee function and maintaining quality of life.

Meniscus Repair Does Not Result in an Inferior Short-term Outcome Compared With Meniscus Resection: An Analysis of 5,378 Patients With Primary Anterior Cruciate Ligament Reconstruction

PURPOSE

To compare the preoperative and 1- and 2-year postoperative Knee Injury and Osteoarthritis Outcome Score (KOOS) subscale scores between isolated anterior cruciate ligament reconstruction (ACLR) and ACLR with additional medial meniscus (MM) and/or lateral meniscus (LM) resection or repair.

METHODS

A total of 5,378 patients who underwent primary ACLR, with no associated ligament injuries, at our institution from January 2005 to December 2015 were included. The KOOS subscale scores were used to evaluate patients preoperatively and at 1- and 2-year postoperative follow-up assessments. Patients who underwent isolated ACLR and those who underwent ACLR with additional MM resection, MM repair, LM resection, LM repair, MM plus LM resection, or MM plus LM repair were compared by use of an analysis of covariance, with age, sex, graft, and cartilage injury as covariates.

RESULTS

Postoperatively, at both 1- and 2-year follow-up assessments, no significant differences were found between the groups for any of the 5 KOOS subscales. Preoperatively, a significant difference between the groups was found for the KOOS Symptoms (P < .001), Pain (P < .001), Activities of Daily Living (ADL) (P < .001), and Sport and Recreation (Sport/Rec) (P = .01) subscale scores. The lowest scores were found for the group undergoing ACLR and MM plus LM repair (Symptoms, 70.1 ± 17.3; Pain, 71.4 ± 18.5; ADL, 80.6 ± 20.5; and Sport/Rec, 35.7 ± 28.1), whereas the mean scores for the other groups ranged from 71.2 ± 18.7 to 76.5 ± 17.1 for Symptoms, from 76.1 ± 17.0 to 80.1 ± 15.5 for Pain, from 84.5 ± 16.8 to 88.1 ± 14.2 for ADL, and from 44.2 ± 28.3 to 49.1 ± 28.5 for Sport/Rec.

CONCLUSIONS

Patients undergoing isolated ACLR and those undergoing ACLR with additional MM and/or LM resection or repair obtained equivalent results for each of the KOOS subscales at the 1- and 2-year postoperative follow-up assessments. Differences between the groups were only detectable preoperatively, with patients undergoing ACLR and MM plus LM repair showing the lowest scores for the KOOS Symptoms, Pain, ADL, and Sport/Rec subscales.

LEVEL OF EVIDENCE

Level III, retrospective comparative therapeutic trial.

Editorial Commentary: Comparing Medial and Lateral Meniscal Root Tears Is Like Comparing Apples and Oranges

The importance of treating meniscal root tears has been increasingly recognized, and surgeons have to make conscious decisions routinely regarding repair for select patients. The clinical and patient demographic differences between medial and lateral meniscal root tears are important and ultimately leave us wondering whether outcome differences are due to unique anatomic factors or the patient population sustaining these injuries.

Age, gender, quadriceps strength and hop test performance are the most important factors affecting the achievement of a patient-acceptable symptom state after ACL reconstruction

PURPOSE

To assess the percentage of patients achieving an acceptable symptom state 2 years after primary anterior cruciate ligament reconstruction (ACLR) and to identify factors affecting its achievement, in a large cohort.

METHODS

Patients who underwent primary ACLR at Capio Artro Clinic, Stockholm, Sweden, from 2005 to 2015, were identified in our clinic registry. Patients who had completed the Knee injury and Osteoarthritis Outcome Score (KOOS) at the 2-year follow-up were included. The primary outcome was the achievement of a patient-acceptable symptom state (PASS) for each KOOS subscale. A multivariate logistic regression analysis was used to determine whether patient age, gender, time from injury to surgery, pre-injury Tegner activity level, graft type, cartilage injury, the presence of medial meniscus (MM) or lateral meniscus (LM) resection or repair and the recovery of 6-month symmetrical (limb symmetry index [LSI] of ≥ 90%) isokinetic quadriceps or hamstring strength and single-leg-hop test performance were factors associated with the achievement of a PASS for each KOOS subscale.

RESULTS

A total of 2335 primary ACLRs were included. More than 60% of the patients reported a PASS on four of the five KOOS subscales. Age ≥ 30 years and an LSI of ≥ 90% for 6-month isokinetic quadriceps strength increased the odds of achieving a PASS across all KOOS subscales. Female gender reduced the odds of achieving a PASS on the Pain (OR 0.76; 95% CI 0.62-0.94; P = 0.01), activities of daily living (ADL) (OR 0.79; 95% CI 0.64-0.97; P = 0.02) and sport and recreation (OR 0.72; 95% CI 0.58-0.89; P = 0.003) subscales. The presence of an MM repair reduced the odds of achieving a PASS on the Pain (OR 0.59; 95% CI 0.36-0.96; P = 0.03) subscale. Hamstring tendon (HT) autograft rather than bone-patellar tendon-bone (BPTB) autograft showed increased odds (OR 2.02; 95% CI 1.31-3.10; P = 0.001), whereas a cartilage injury showed reduced odds (OR 0.73; 95% CI 0.55-0.97; P = 0.03) of achieving a PASS on the sport and recreation subscale. An LSI of ≥ 90% for 6-month single-leg-hop test performance increased the odds of achieving a PASS on the ADL (OR 1.37; 95% CI 1.09-1.71; P = 0.005), Sport and Recreation (OR 1.40; 95% CI 1.11-1.77; P = 0.004), and quality of life (OR 1.28; 95% CI 1.00-1.63; P = 0.04) subscales.

CONCLUSION

More than 60% of the patients reported an acceptable symptom state on four of the five KOOS subscales 2 years after primary ACLR. Age ≥ 30 years and female gender were the non-modifiable factors that consistently increased and reduced, respectively, the odds of achieving a PASS. A symmetrical 6-month isokinetic quadriceps strength and single-leg-hop test performance were the modifiable factors that consistently increased the opportunity of achieving a PASS 2 years after primary ACLR.

LEVEL OF EVIDENCE

III.

The Meniscus Tear: A Review of Stem Cell Therapies

Meniscal injuries have posed a challenging problem for many years, especially considering that historically the meniscus was considered to be a structure with no important role in the knee joint. This led to earlier treatments aiming at the removal of the entire structure in a procedure known as a meniscectomy. However, with the current understanding of the function and roles of the meniscus, meniscectomy has been identified to accelerate joint degradation significantly and is no longer a preferred treatment option in meniscal tears. Current therapies are now focused to regenerate, repair, or replace the injured meniscus to restore its native function. Repairs have improved in technique and materials over time, with various implant devices being utilized and developed. More recently, strategies have applied stem cells, tissue engineering, and their combination to potentiate healing to achieve superior quality repair tissue and retard the joint degeneration associated with an injured or inadequately functioning meniscus. Accordingly, the purpose of this current review is to summarize the current available pre-clinical and clinical literature using stem cells and tissue engineering for meniscal repair and regeneration.

The interrelationship between anterior cruciate ligament tibial footprint and anterolateral meniscal root insertions: Quantitative, morphological and positional analyses using three-dimensional computed tomography images

BACKGROUND

The purpose of this study was to evaluate quantitative, morphological and positional differences between the anterior cruciate ligament (ACL) tibial footprint and anterolateral meniscal root (ALMR) insertion and investigate an intraoperative landmark to estimate their boundaries.

METHODS

Thirty-three fixed human cadaveric knees were evaluated. After resecting the components, the anterior fiber (AF) and posterior fiber (PF) of ALMR, the tibial center of ACL bundles (anteromedial (AM) and posterolateral (PL) bundles) and ACL were marked. Insertion morphology was classified into three categories, and the distance and relative positional relationship between AF/PF insertions and the center of each attachment were measured on three-dimensional computed tomography images.

RESULTS

There was no significant difference between the AF of AM and ACL (P = 0.16), but both were significantly shorter than the AF of PL (both P < 0.001). There was no significant difference between the PF of ACL and PL (P = 0.99), which were significantly shorter than PF of AM (both P < 0.001). Morphology of the ACL tibial insertion was classified as follows: triangular, 15 knees (45.5%); oval, 18 knees (54.5%); none, C-shape. Quantitative and positional analyses showed that the AF insertion was significantly closer to AM and ACL centers in the oval type than in the triangular type. Excluding two cases, the AF/PF insertion was located laterally to the ML center of the medial and lateral intercondylar tubercles.

CONCLUSION

Proximity of ACL tibial footprint and ALMR varies by their footprint morphology. The medial and lateral intercondylar tubercles were useful landmarks for ALMR injury prevention.

Type II Medial Meniscus Root Repair With Peripheral Release for Addressing Meniscal Extrusion

Medial meniscal root tears are often disabling injuries that can occur in isolation during low-velocity, deep knee flexion maneuvers in middle-aged patients. The most common meniscal root tear pattern is a radial tear near the root attachment (type II). Root tears are often associated with meniscal extrusion, identified on magnetic resonance imaging. Relocation of the meniscal root to its anatomic center is a reported current difficulty faced by surgeons during surgical repair. However, this can be achieved via sufficient peripheral release of the posteromedial capsular attachment of the medial meniscus. The purpose of this Technical Note is to describe the authors' current surgical technique for medial meniscus root repair with a peripheral release for addressing meniscal extrusion. Classifications: level I (knee); level II (meniscus).

A novel suture technique to reduce the meniscus extrusion in the pullout repair for medial meniscus posterior root tears

The medial meniscus (MM) posterior root has important functions in preventing an excessive loading stress during knee motion and degeneration of the articular cartilage. Although the transtibial pullout repair has become the gold standard for MM posterior root tears (MMPRTs), MM extrusion remains. In addition, during knee extension to deep flexion, the MM posterior segment in the MMPRT knee has been shown to translate toward the posteromedial direction, causing a notable MM posterior extrusion. Thus, the reduction in the MM posteromedial extrusion is one of the important postoperative outcomes to restore the meniscal function and eventually prevent the progression of knee osteoarthritis. The present technical note describes an arthroscopic technique addition to the pullout repair, in which an all-inside suture is inserted into the posteromedial part of the MM to reduce the MM posteromedial extrusion.

Tibial insertion of the anterior cruciate ligament and anterior horn of the lateral meniscus share the lateral slope of the medial intercondylar ridge: A computed tomography study in a young, healthy population

BACKGROUND

The central intercondylar ridge (CIR) is an anatomical bony landmark that bisects the slope of the medial intercondylar ridge (MIR) between the tibial insertion of the anterior cruciate ligament (ACL) and anterior horn of lateral meniscus (AHLM) and was recently revealed by computed tomography (CT) evaluation corresponding to histologic slices of cadaveric knees. The purpose of this study was to clarify the shape and size of ACL and AHLM tibial insertion in young, healthy knees using the new bony landmark (CIR) and previously reported landmarks.

METHODS

The contralateral healthy knees in 34 ACL-reconstructed patients (18 male patients, 16 female patients, mean age: 24.0 years) were scanned by CT. In the reconstructed coronal/sagittal images, bony landmarks of ACL (anterior: anterior ridge, posterior: blood vessel in tubercle fossa, medial: MIR, lateral: CIR) and AHLM (medial: CIR, lateral: bottom of the slope) were plotted for evaluation. The length of sagittal slices and the width in five coronal slices of the insertion were measured.

RESULTS

The ACL insertion consistently showed a boot-like-shape adjacent to the square shape of AHLM on three-dimensional imaging. The mean ACL sagittal length was 14.5 ± 1.9 mm, while the mean ACL widths (in mm) from anterior to posterior were 12.7 ± 2.7, 8.1 ± 1.9, 7.9 ± 2.0, 7.5 ± 1.5, and 7.2 ± 1.6, which was highly correlated with the tibial plateau size.

CONCLUSIONS

The boot-like-shape of the ACL tibial footprint insertion shared the slope of MIR with the rectangular shape of AHLM in young, healthy knees. This study may provide useful information for safe tibial tunnel creation at the time of ACL reconstruction.

Relationship between anterior cruciate ligament and anterolateral meniscal root bony attachment: High-resolution 3-T MRI analysis

BACKGROUND

The tibial bony attachments of the anterior cruciate ligament (ACL) and the anterolateral meniscal root (ALMR) are very close, and drilling the tibial tunnel in ACL reconstruction may damage the ALMR attachment. This study investigated the relationship between the tibial attachment of the ACL and ALMR using high-resolution 3-T magnetic resonance imaging (MRI).

METHODS

Twenty healthy subjects (35.8 ± 13.0 years) had 20 knees scanned using high resolution 3-T MRI. The tibial bony attachments of ACL, ALMR, and the tibia were segmented and three-dimensional models were created. The shape, area, and location of each attachment were evaluated using this model.

RESULTS

The ACL tibial attachment was elliptical in nine knees (45%), C-shaped in nine knees (45%) and triangle in two knees (10%). The mean values of the ACL vs ALMR tibial attachments were as follows: area, 106.2 ± 21.3 vs 56.2 ± 21.3 mm²; length, 16.8 ± 2.0 vs 11.0 ± 1.8 mm; and width, 6.9 ± 1.3 vs 6.6 ± 1.0 mm. The location of the ACL vs ALMR attachment centres was 46.5 ± 1.7% vs 56.5 ± 1.9% in the medial-lateral direction and 36.3 ± 3.6% vs 36.7 ± 3.5% in the anterior-posterior direction. The distance between the ACL and ALMR centres was 8.1 ± 1.3 mm.

CONCLUSIONS

ACL and ALMR tibial attachments were individually distinguished using high resolution 3-T MRI. The short distance between both centres of the attachments may suggest that ALMR can be damaged when the tibial tunnel is drilled in ACL reconstruction.

Anatomical relationship between insertion sites, tunnel placement, and lateral meniscus anterior horn injury during single and double bundle anterior cruciate ligament reconstructions: A comparative macroscopic and histopathological evaluation in cadavers

PURPOSE

The influence of tunnel extension outside the anatomical anterior cruciate ligament (ACL) insertion in single-bundle (SB) or double-bundle (DB) ACL reconstruction is unclear. This study aimed to investigate the anatomical relationship between ACL insertion and tunnel extension in SB and DB ACL reconstruction, and the impact of tibial tunnel extension to the insertion of anterior horn of lateral meniscus in terms of injury.

METHODS

Forty-six paired cadaver knees (mean age, 82.7 ± 10.7 years) were used. Right and left knees were used for SB (10 mm) and DB tunnel reaming (6 mm for the anteromedial and posterolateral bundles). Tibial and femoral tunnels were created to aim at the center of the ACL insertion by arthroscopic visualization. The relationship between tunnel extension and ACL insertion was evaluated macroscopically, and there ratio in two groups were compared by chi-square test. Further, the relative risk for meniscus injury based on tunnel placement was estimated. Coronal section of tibia and parallel section to Blumensaat line in femur were prepared to evaluate the relationship among tunnel position, ACL insertion, and anterior horn of the meniscus histologically.

RESULTS

Tibial tunnel extension out of the ACL insertion was observed macroscopically in 9 (39.1%) knees of the SB group, and 3 (13.0%) of the DB group (p = 0.045). In femoral tunnels, extension out of the ACL insertion was seen in 8 (34.8%) knees of the SB group and 1 (4.3%) of the DB group (p = 0.011). Partial injuries of the lateral meniscus anterior horn (LMAH) were observed in 5 (21.7%) knees of the SB group and 1 (4.3%) knee of the DB group (p = 0.091). The relative risk for LMAH injury was calculated as 5.0 (odds ratio, 6.1). Microscopically, SB tunnels appeared to expand out of ACL insertion, both in the femur and tibia.

CONCLUSIONS

The incidence of tunnel extension out of the ACL insertion in femur and tibia were higher with SB than with DB reconstruction. Furthermore, injury rate of the LMAH in the DB group was lower.

The Biomechanics of Multiligament Knee Injuries: From Trauma to Treatment

The multiple ligament injured knee is a complex biomechanical environment. When primary stabilizers fail, secondary stabilizers have an increased role. In addition, loss of primary restraints puts undue stress on the remaining intact structures of the knee. Treatment of these injuries requires accurate diagnosis of all injured structures, and careful consideration of repairs and reconstructions that restore the synergistic stability of all ligaments in the knee.

Minimal Ablation of the Tibial Stump Using Bony Landmarks Improved Stability and Synovial Coverage Following Double-Bundle Anterior Cruciate Ligament Reconstruction

Purpose

To evaluate the clinical effects of using anatomical bony landmarks (Parsons’ knob and the medial intercondylar ridge) and minimal ablation of the tibial footprint to improve knee anterior instability and synovial graft coverage after double-bundle anterior cruciate ligament reconstruction.

Materials and Methods

We performed a retrospective comparison of outcomes between patients who underwent reconstruction with minimal ablation of the tibial footprint, using an anatomical tibial bony landmark technique, and those who underwent reconstruction with wide ablation of the tibial footprint. Differences between the two groups were evaluated using second-look arthroscopy, radiological assessment of the tunnel position, postoperative anterior knee joint laxity, and clinical outcomes.

Results

Use of the anatomical reference and minimal ablation of the tibial footprint resulted in a more anterior positioning of the tibial tunnel, with greater synovial coverage of the graft postoperatively (p=0.01), and improved anterior stability of the knee on second-look arthroscopy. Both groups had comparable clinical outcomes.

Conclusions

Use of anatomical tibial bony landmarks that resulted in a more anteromedial tibial tunnel position improved anterior knee laxity, and minimal ablation improved synovial coverage of the graft; however, it did not significantly improve subjective and functional short-term outcomes.

Stereophotogrammetric surface anatomy of the anterior cruciate ligament's tibial footprint: Precise osseous structure and distances to arthroscopically-relevant landmarks

BACKGROUND

While femoral tunnel malposition is widely recognized as the main technical error of failed anterior cruciate ligament (ACL) surgery, tibial tunnel malposition is likely underrecognized and underappreciated.

PURPOSE

To describe more precisely the qualitative and quantitative anatomy of the ACL's tibial attachment in vitro using widely available technology for stereophotogrammetric surface reconstruction, and to test its applicability in vivo.

METHODS

Stereophotogrammetric surface reconstruction was obtained from fourteen proximal tibias of cadaver donors. Measurements of areas and distances from the center of the ACL footprint and the footprint of the obtained bundles to selected arthroscopically-relevant anatomic landmarks were carried out using a three-dimensional design software program, and means and 95% confidence intervals were calculated for these measurements. Reference landmarks were tested in three-dimensional models obtained with arthroscopic videos.

MAIN FINDINGS

The osseous footprint of the ACL was described in detail, including its precise elevated limits, size, and shape, with its elevation pattern described as a quarter-turn-staircase-like ridge. Its internal indentations were related to inter-spaces identified as bundle divisions. Distances from the footprint center to arthroscopically relevant landmarks were obtained and compared to its internal structure, yielding a useful X-like landmark pointing to the most accurate placeholder for the ACL footprint's "anatomic" center. Certain structures and reference landmarks described were readily recognized in three-dimensional models from arthroscopic videos.

CONCLUSIONS

Stereophotogrammetric surface reconstruction is an accessible technique for the investigation of anatomic structures in vitro, offering a detailed three-dimensional depiction of the ACL's osseous footprint.

Editorial Commentary: Small Incisions Can Make Big Mistakes: Knee Lateral Collateral Ligament Reconstruction Is All About the Anatomy!

It is becoming increasingly recognized that isolated lateral collateral ligament (LCL) tears are more common than have been previously recognized and that anatomic-based LCL reconstructions have the best outcomes. Although it was believed that posterolateral corner injuries were often missed or mistreated and were given the pneumonic of "the dark side of the knee," we are getting to the point where most of these more severe injuries are being recognized, and it is the isolated LCL injuries that are still less well recognized. Failure to treat LCL tears at the same time as a cruciate ligament reconstruction is a well-known cause of both anterior cruciate ligament and posterior cruciate ligament reconstruction graft failure. Therefore, either having the required clinical experience or knowledge, or using a radiographic backup method when one is not sure about the anatomic placement, is essential to correctly perform an LCL reconstruction.

Knotless Suture Anchor Repair of Anterolateral Meniscus Root After Iatrogenic Injury

In recent years there has been increased attention on preserving the menisci because they perform vital roles in maintaining knee joint homeostasis. The anterolateral (AL) meniscal root is particularly vulnerable during anterior cruciate ligament reconstruction. When the AL root is iatrogenically injured, it is imperative that it is repaired in a timely fashion to prevent early-onset osteoarthritis. In this article we outline our knotless suture anchor repair for AL root tears.

Capsulodesis Versus Bone Trough Technique in Lateral Meniscal Allograft Transplantation: Graft Extrusion and Functional Results

PURPOSE

To compare the radiographic results (in terms of graft extrusion) and the functional results of lateral meniscus allograft transplantations (MAT) performed with a bony fixation technique or with a soft tissue fixation technique after capsulodesis.

METHODS

A prospective series of 29 consecutive lateral MAT was analyzed. The inclusion criterion for MAT was lateral joint line pain due to a previous meniscectomy. Malalignment, patients who had an Ahlback grade greater than II, and patients with a body mass index over 30 were considered as the exclusion criterion to prevent confounding results. Fifteen of the grafts were fixed with a bony fixation technique (group A). The remaining 14 cases (group B) were fixed with sutures through bone tunnels after lateral capsular fixation (capsulodesis). All patients were studied with magnetic resonance imaging to determine the degree of meniscal extrusion at an average of 18 months of surgery (range, 12-48 months). Meniscal extrusion was measured on coronal magnetic resonance imaging. To standardize the results, the percentage of meniscus extruded for each group was also calculated and compared. The functional results were analyzed by means of standard knee scores (Lysholm, Tegner, and visual analog scale).

RESULTS

If we consider the first 4 cases of group B as the learning curve of the new technique, we observe that group A had 8 cases (53.3%) of major extrusion, whereas group B had 1 case (7.1%) (P = .02). When comparing the degree of meniscal extrusion with the type of fixation employed, an even lower percentage of extruded menisci was found in group B (P = .01). The final follow-up Lysholm score in group A was 94.33 ± 5.96 (P < .001) and 91.43 ± 6.19 (P < .001) in group B. The median follow-up Tegner score significantly improved from 4 (range, 2-5) to 7 (range, 6-9) in group A (P < .001) and from 4 (range, 3-5) to 7 (range, 6-8) in group B (P < .001). The average visual analog scale score dropped down 5.87 and 7.29 points in groups A and B, respectively (P < .001). The Knee Injury and Osteoarthritis Outcome Score improved from 51.98 ± 2.84 to 90.88 ± 7.53 in group A (P < .001) and from 50.44 ± 2.32 to 92.01 ± 6.71 in group B (P < .001). Patient satisfaction with regard to the procedure stood at a mean of 3.6 ± 0.2 points out of a maximum of 4 in group A and 3.8 ± 0.4 in group B. There were no complications in this series.

CONCLUSIONS

The capsulodesis technique in lateral MAT proved not to be statistically different at decreasing the degree of meniscal extrusion with respect to the bone-bridge fixation. If the first 4 cases using the new capsulodesis technique had not included in the results, the capsulodesis technique would have effectively presented better results relative to the degree of meniscal extrusion compared with the bone-bridge fixation technique. In addition, the functional results were similar.

LEVEL OF EVIDENCE

Level II, prospective comparative study.