Dynamic contact mechanics of the medial meniscus as a function of radial tear, repair, and partial meniscectomy

Arthroscopic repair of the meniscus: Surgical management and clinical outcomes

From the biomechanical and biological points of view, an arthroscopic meniscal repair (AMR) should always be considered as an option. However, AMR has a higher reoperation rate compared with arthroscopic partial meniscectomy, so it should be carefully indicated.

Compared with meniscectomy, AMR outcomes are better and the incidence of osteoarthritis is lower when it is well indicated.

Factors influencing healing and satisfactory results must be carefully evaluated before indicating an AMR.

Tears in the peripheral third are more likely to heal than those in the inner thirds.

Vertical peripheral longitudinal tears are the best scenario in terms of success when facing an AMR.

‘Inside-out’ techniques were considered as the gold standard for large repairs on mid-body and posterior parts of the meniscus. However, recent studies do not demonstrate differences regarding failure rate, functional outcomes and complications, when compared with the ‘all-inside’ techniques.

Some biological therapies try to enhance meniscal repair success but their efficacy needs further research. These are: mechanical stimulation, supplemental bone marrow stimulation, platelet rich plasma, stem cell therapy, and scaffolds and membranes.

Meniscal root tear/avulsion dramatically compromises meniscal stability, accelerating cartilage degeneration. Several options for reattachment have been proposed, but no differences between them have been established. However, repair of these lesions is actually the reference of the treatment.

Meniscal ramp lesions consist of disruption of the peripheral attachment of the meniscus. In contrast, with meniscal root tears, the treatment of reference has not yet been well established.

Cite this article: EFORT Open Rev 2018;3:584-594. DOI: 10.1302/2058-5241.3.170059

Tibiofemoral Contact Mechanics With Horizontal Cleavage Tears and Treatment of the Lateral Meniscus in the Human Knee: An In Vitro Cadaver Study

BACKGROUND

Partial meniscectomy is one of the most commonly performed orthopaedic procedures for a meniscus tear. Decreased contact area and increased contact pressure have been seen in partial meniscectomies from treatment of various types of meniscal tears; however, the biomechanical effect of a horizontal cleavage tear in the lateral meniscus and subsequent treatment are unknown.

QUESTIONS/PURPOSES

This study asked whether a horizontal cleavage tear of the lateral meniscus, resecting the inferior leaf, and further resecting the superior leaf would (1) decrease contact area and (2) increase peak contact pressure.

METHODS

Eleven fresh-frozen human cadaveric knees were evaluated under five conditions of intact meniscus, horizontal cleavage tear, inferior leaf resection, and resection of the inferior and superior leaves of the lateral meniscus. Tibiofemoral contact area and pressure were measured at 0° and 60° knee flexion under an 800-N load, normalized to that at the intact condition of the corresponding knee flexion, and compared across the five previously described conditions.

RESULTS

At 0° knee flexion, normalized contact area with inferior leaf resection (65.4% ± 14.1%) was smaller than that at the intact condition (100% ± 0.0%, p < 0.001); smaller than horizontal cleavage tear (94.1% ± 5.8%, p = 0.001) contact area; and smaller than repaired horizontal tear (92.8% ± 8.2%, p = 0.001) contact area. Normalized contact area with further superior leaf resection (50.5% ± 7.3%) was smaller than that at the intact condition (100% ± 0.0%, p < 0.001); smaller than horizontal cleavage tear (94.1% ± 5.8%, p < 0.001) contact area; and smaller than repaired horizontal tear (92.8% ± 8.2%, p < 0.001) contact area. At 60° flexion, normalized contact area with inferior leaf resection (76.1% ± 14.8%) was smaller than that at the intact condition (100% ± 0.0%, p = 0.004); smaller than horizontal cleavage tear (101.8% ± 7.2%, p = 0.006) contact area; and smaller than repaired horizontal tear (104.0% ± 13.3%, p < 0.001) contact area. Normalized contact area with further superior leaf resection (52.1% ± 16.7%) was smaller than that at the intact condition (100% ± 0.0%, p < 0.001); smaller than horizontal cleavage tear (101.8% ± 7.2%, p < 0.001) contact area; and smaller than repaired horizontal tear (104.0% ± 13.3%, p < 0.001) contact area. At 60° flexion, contact area with both leaf resection (52.1% ± 16.7%) was smaller than that with inferior leaf resection (76.1% ± 14.8%, p = 0.039). At 0° knee flexion, peak pressure increased to 127.0% ± 22.1% with inferior leaf resection (p = 0.026) and to 138.6% ± 24.3% with further superior leaf resection (p = 0.002) compared with that at the intact condition (100% ± 0.0%). At 60° flexion, compared with that at the intact condition (100% ± 0.0%), peak pressure increased to 139% ± 33.6% with inferior leaf resection (p = 0.035) and to 155.5% ± 34.7% (p = 0.004) with further superior leaf resection.

CONCLUSIONS

Resection of the inferior leaf or both leaves of the lateral meniscus after a horizontal cleavage tear resulted in decreased contact area and increased peak contact pressure at 0° and 60° knee flexion.

CLINICAL RELEVANCE

In vitro resection of one or both leaves of a horizontal cleavage tear of the lateral meniscus causes increases in peak pressure, consistent with other types of partial meniscectomies associated in a clinical setting with excessive loading and damage to knee cartilage. Clinical outcomes in patients undergoing partial leaf meniscectomy could confirm this theory. Avoidance of resection may be relatively beneficial for long-term function. The findings of this in vitro study lend biomechanical support for nonoperative management.

Current concepts in the techniques, indications and outcomes of meniscal repairs

Knee arthroscopy for meniscal tears is one of the most commonly performed orthopaedic procedures. In recent years, there has been an increasing incidence of meniscal repairs, as there are concerns that meniscectomy predisposes patients to early osteoarthritis. Indications for meniscal repair are increasing and can now be performed in older patients who are active, even if the tear is in the avascular zone. Options for meniscal tear management broadly fall into three categories: non-operative management, meniscal repair or meniscectomy. With limited evidence directly comparing each of these options optimal management strategies can be difficult. Decision making requires thorough assessment of patient factors (e.g. age and comorbidities) and tear characteristics (e.g. location and reducibility). The purpose of this paper is, therefore, to review the management options of meniscal tears and summarize the evidence for meniscal tear repair.

Quantified in vitro tibiofemoral contact during bodyweight back squats

Squats are a common lower extremity task used in strength and conditioning, balance training, and rehabilitation. It is important to understand how slight alterations in lower extremity kinematics during a squat affect the internal joint loading of the knee. This study directly quantified tibiofemoral contact throughout the in vitro simulation of a bodyweight back squat performed two ways: a heel squat (knees in line with toes) and a toe squat (knees anterior to the toes) at peak knee flexion. Three cadaveric right lower extremities were instrumented and positioned into the University of Texas Joint Load Simulator. Kinematics, kinetics, and predicted muscle forces from a 20-year-old athletic male performing the two back squats were used as inputs for the in vitro simulations. The quantified tibiofemoral contact area, peak pressure, net force, and center of pressure location were significantly different between squat types (p > 0.05). Net contact area on the tibial plateau at peak knee flexion was significantly larger in the heel versus toe squat (599 ± 80 mm² vs. 469 ± 125 mm²; p < 0.05). Peak lateral pressure was significantly higher in the heel versus toe squat (2.73 ± 0.54 MPa vs. 0.87 ± 0.56 MPa; p < 0.05). Results suggest the heel squat generates an even load distribution, which is less likely to affect joint degeneration. Future in vitro simulations should quantify the effects lower extremity kinematics, kinetics, and individual muscle forces have on tibiofemoral contact parameters during common athletic tasks.

Tibiofemoral joint contact area and stress after single-bundle anterior cruciate ligament reconstruction with transtibial versus anteromedial portal drilling techniques

Background

During single-bundle ACLR, femoral tunnel location plays an important role in restoring the intact knee mechanisms, whereas malplacement of the tunnel was cited as the most common cause of knee instability. The objective of this study is to evaluate, objectively, the tibiofemoral contact area and stress after single-bundle (SB) anterior cruciate ligament reconstruction (ACLR) with femoral tunnel positions drilled by transtibial (TT) or anteromedial (AM) portal techniques.

Methods

Seven fresh human cadaveric knees underwent ACLR by the use of TT or AM portal techniques in a randomized order. These specimens were reused for ACL-R (TT and AM). The tibiofemoral contact area and stresses were gauged by an electronic stress-sensitive film inserted into the joint space. The knee was under the femoral axial compressive load of 1000 N using a biomechanics testing machine at 0°, 10°, 20°, and 30° of flexion. Three conditions were compared: (1) intact ACL, (2) ACLR by the use of the TT method, and (3) ACLR by the use of the AM portal method.

Results

Compared with AM portal ACL-reconstructed knees, a significantly decreased tibiofemoral contact area on the medial compartment was detected in the TT ACL-reconstructed knees at 20°of knee flexion (P = .047). Compared with the intact group, the TT ACLR group showed a higher mean stress at 20° and 30° of flexion on the medial compartments (P = .001, P = .003, respectively), while the AM portal ACLR group showed no significant differences at 30° of flexion (P = .073). The TT ACLR group also showed a higher mean maximum stress at 20° of flexion on the medial compartments (P = .047), while the AM portal ACLR group showed no significant differences at this angle(P = .319).

Discussion

The alternation of the tibiofemoral joint contact area and stress in reconstructed knees may be caused by the mismatch of the tibiofemoral joint during knee movement procedures compared with intact knees.

Conclusions

SB ACLR by the use of the AM portal method and TT method both alter the tibiofemoral contact area and stress when compared with the intact knee. When compared with the TT technique, ACLR by the AM portal technique more closely restores the intact tibiofemoral contact area and stress at low flexion angles.

"Horizontal butterfly" technique in repair of radial meniscus tears: A biomechanical study

Introduction

Radial meniscus tears are seen in young patients, especially with anterior cruciate ligament ruptures. Repair of complete radial meniscus tear is necessary for the meniscus functions. The most important factor for success of the meniscus repair is primary stability, but it is still unknown which technique is ideal repair technique.

Aim

We developed a new suture technique named Horizontal Butterfly (HB). In this novel technique the contact between meniscal tissue and suture is more than Horizontal Loop (HL) that routinely used today. So, we think that this technique will provide better fixation than HL. We aimed to compare 2 repair techniques (HB vs. HL) using human lateral menisci biomechanically with cyclic loading and load to failure tests.

Material-method

We used 22 intact lateral meniscus obtained from patients that operated (total knee replacement) for varus gonarthrosis in our clinic. All menisci were cut radially. In the first group (n:11) menisci were repaired with standard horizontal loop technique, and in the second group (n:11) horizontal butterfly technique were used for repair. All specimens were tested with load to failure test after cyclic loading test (500 cycle X 5–30 N).

Results

Both groups have similar failure load (71,4 ± 17,52 N vs. 77,9 ± 28,49 N; p:0,559) and stiffness (24,46 ± 19,19 N vs. 24,48 ± 15,87 N; p:0,818). HB group has less peak displacement (6,26 ± 1,24 mm vs. 8,4 ± 1,92 mm; p:0,010).

Conclusion

This novel repair technique decreases the amount of displacement according to standard technique while as strong as standard technique routinely used. In this way; we believe that it will increase the rate of healing in clinical use.

Osteochondral Lesions of the Knee: Differentiating the Most Common Entities at MRI

Several pathologic conditions may manifest as an osteochondral lesion of the knee that consists of a localized abnormality involving subchondral marrow, subchondral bone, and articular cartilage. Although understanding of these conditions has evolved substantially with the use of high-spatial-resolution MRI and histologic correlation, it is impeded by inconsistent terminology and ambiguous abbreviations. Common entities include acute traumatic osteochondral injuries, subchondral insufficiency fracture, so-called spontaneous osteonecrosis of the knee, avascular necrosis, osteochondritis dissecans, and localized osteochondral abnormalities in osteoarthritis. Patient demographics, the clinical presentation, and the role of trauma are critical for differential diagnosis. A localized osteochondral defect can be created acutely or can develop as an end result of several chronic conditions. MRI features that aid in diagnosis include the location and extent of bone marrow edema, the presence of a fracture line, a hypointense area immediately subjacent to the subchondral bone plate, and deformity of the subchondral bone plate. These findings are essential in diagnosis of acute traumatic injuries, subchondral insufficiency fracture, and its potentially irreversible form, spontaneous osteonecrosis of the knee. If the lesion consists of a subchondral region demarcated from the surrounding bone, the demarcation should be examined for completeness and the presence of a "double-line sign" that is seen in avascular necrosis or findings of instability, which are important for proper evaluation of osteochondritis dissecans. Subchondral bone plate collapse, demonstrated by the presence of a depression or a fluid-filled cleft, can be seen in advanced stages of both avascular necrosis and subchondral insufficiency fracture, indicating irreversibility. Once the diagnosis is established, it is important to report pertinent MRI findings that may guide treatment of each condition. ^©RSNA, 2018 An earlier incorrect version of this article appeared online. This article was corrected on August 23, 2018.

Radial Tears of the Lateral Meniscus-Two Novel Repair Techniques: A Biomechanical Study

Background:

A common treatment for radial tears of the meniscus has historically been partial meniscectomy. Owing to the poor outcomes associated with partial meniscectomy, repair of the meniscus is an important treatment option. It is important to evaluate different repair techniques for radial tears of the meniscus.

Purpose/Hypothesis:

The purpose of this study was to evaluate 2 novel techniques to repair radial tears of the lateral meniscus. The 2 techniques were compared biomechanically with the cross-suture method with an inside-out technique. The authors hypothesized that novel repair techniques would result in less displacement after cyclic loading, increased load required to displace the repair 3 mm, greater load to failure, decreased displacement at load to failure, and increased stiffness of the repair, resulting in a construct that more closely re-creates the function of the intact meniscus.

Study Design:

Controlled laboratory study.

Methods:

A total of 36 fresh-frozen cadaveric tibial plateaus containing intact menisci were obtained. The menisci were divided into 3 groups (n = 12 in each group), and each meniscus was repaired simulating an inside-out technique. The 3 repairs completed were the hashtag, crosstag, and cross-suture techniques. Radial tears were created at the midbody of the lateral meniscus and repaired via the 3 techniques. The repaired menisci were attached to an axial loading machine and tested for cyclic and failure loading.

Results:

After cyclic loading, the cross-suture repair displaced 4.78 ± 1.65 mm; the hashtag, 2.42 ± 1.13 mm; and the crosstag, 3.13 ± 1.77 mm. The hashtag and cross-tag repairs both resulted in significantly less displacement (P = .003 and .024, respectively) as compared with the cross-suture repair. The cross-suture technique had a load to failure of 81.43 ± 14.31 N; the hashtag, 86.08 ± 23.58 N; and the crosstag, 62.50 ± 12.15 N. The cross-suture and hashtag repairs both resulted in a greater load to failure when compared with the crosstag (P = .009 and .009, respectively). There was no difference comparing the load required to displace the cross-suture technique 3 mm versus the hashtag or crosstag technique (P = .564 and .094, respectively). However, when compared with the crosstag technique, the hashtag technique required a significantly greater load to displace the repair 3 mm (P = .015).

Conclusion:

This study introduced 2 novel repair techniques—hashtag and crosstag—that did not demonstrate superiority in terms of load to failure or stiffness, but both repairs were statistically superior to the cross-suture repair in terms of displacement after cyclic loading. Considerations that may influence the validity of these techniques include cost, surgical time, and increased technical demand.

Clinical Relevance:

Radial tears of the meniscus are difficult to repair. Further research into more stable constructs is necessary.

A computational algorithm to simulate disorganization of collagen network in injured articular cartilage

Cartilage defects are a known risk factor for osteoarthritis. Estimation of structural changes in these defects could help us to identify high risk defects and thus to identify patients that are susceptible for the onset and progression of osteoarthritis. Here, we present an algorithm combined with computational modeling to simulate the disorganization of collagen fibril network in injured cartilage. Several potential triggers for collagen disorganization were tested in the algorithm following the assumption that disorganization is dependent on the mechanical stimulus of the tissue. We found that tensile tissue stimulus alone was unable to preserve collagen architecture in intact cartilage as collagen network reoriented throughout the cartilage thickness. However, when collagen reorientation was based on both tensile tissue stimulus and tensile collagen fibril strains or stresses, the collagen network architecture was preserved in intact cartilage. Using the same approach, substantial collagen reorientation was predicted locally near the cartilage defect and particularly at the cartilage-bone interface. The developed algorithm was able to predict similar structural findings reported in the literature that are associated with experimentally observed remodeling in articular cartilage. The proposed algorithm, if further validated, could help to predict structural changes in articular cartilage following post-traumatic injury potentially advancing to impaired cartilage function.

The role of biomaterials in the treatment of meniscal tears

Extensive investigations over the recent decades have established the anatomical, biomechanical and functional importance of the meniscus in the knee joint. As a functioning part of the joint, it serves to prevent the deterioration of articular cartilage and subsequent osteoarthritis. To this end, meniscus repair and regeneration is of particular interest from the biomaterial, bioengineering and orthopaedic research community. Even though meniscal research is previously of a considerable volume, the research community with evolving material science, biology and medical advances are all pushing toward emerging novel solutions and approaches to the successful treatment of meniscal difficulties. This review presents a tactical evaluation of the latest biomaterials, experiments to simulate meniscal tears and the state-of-the-art materials and strategies currently used to treat tears.

Editorial Commentary: Obese and Overweight: Should They Be Concerned About the Long-Term Consequences of a Partial Meniscectomy?

Is obesity associated with inferior outcomes after partial meniscectomies? Recent research using data from the Chondral Lesions and Meniscus Procedures trial could not demonstrate any differences in obese and overweight patients compared with individuals with a normal body mass index. However, the inclusion of multiple confounders, and a short follow-up of only 1 year limit the validity of their study and the results must be viewed with great caution.

All-inside Arthroscopic Meniscal Repair Technique Using a Midbody Accessory Portal

Treatment of symptomatic meniscal tears continues to evolve as we improve our understanding of the biomechanical role of the meniscus and its long-term importance to the health of the knee joint. Suture repair of meniscal tears is challenging, yet the incidence of repairs among our colleagues continues to rise as we aim to preserve meniscal tissue. Many elements of performing a repair are tedious and difficult, including proper meniscal preparation, reduction, mattress suture placement, and fixation. The tear pattern and location present another layer of difficulty. The most widely used all-inside repair devices are harpoon-style devices and present their own challenges in using them without causing harm to the meniscus and surrounding cartilage. In this article, we describe a simple all-inside meniscal repair technique to improve the reproducibility and reliability of meniscal repairs using an accessory midbody meniscal portal and a surgical probe. This ensures proper placement of mattress sutures in a reduced meniscus, with a reduced risk of collateral injury to the meniscus and articular cartilage. Furthermore, this surgical technique is adaptable to any meniscal fixation method to the medial or lateral meniscus.

Reducing uncertainty when using knee-specific finite element models by assessing the effect of input parameters

Little is known about knee-specific factors that influence contact mechanics. Finite Element (FE) models offer a powerful tool to study contact mechanics, but there often exists ambiguity in the exact values of the inputs (e.g., tissue properties), which can result in a range of output values. Our objective was to quantify the reduction in the range of output values (defined herein as "uncertainty") from FE models of the human knee joint when known pre-defined values are used for clinically measurable inputs. To achieve this goal, we applied a statistically augmented FE approach to three human cadaveric knees for which full geometric and kinematic data were available. Two sets of conditions were simulated: All model inputs, clinically measurable or not, were varied to represent a "normal" patient population (Condition 1); subsets of clinically measurable variable inputs were fixed at specific values (called "patient derived inputs," or PDIs) while the other variables were varied over "normal" values (Condition 2). We found that by fixing body mass index and the anterior-posterior position of the meniscal-bony insertion points, model output uncertainty was reduced by one- to three-fifths. The magnitude of uncertainty reduction was strongly influenced by the individual knee. It was observed that knees with great anterior-posterior translation during gait had greater reductions in uncertainty when PDIs were used. This study represents the first step in developing FE models of the human knee joint based on inputs that can be derived from patients in a clinical setting. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:2233-2242, 2017.

Influence of meniscus on cartilage and subchondral bone features of knees from older individuals: A cadaver study

Objective

Cartilage and subchondral bone form a functional unit. Here, we aimed to examine the effect of meniscus coverage on the characteristics of this unit in knees of older individuals.

Methods

We assessed the hyaline cartilage, subchondral cortical plate (SCP), and subchondral trabecular bone in areas covered or uncovered by the meniscus from normal cadaver knees (without degeneration). Bone cores harvested from the medial tibial plateau at locations uncovered (central), partially covered (posterior), and completely covered (peripheral) by the meniscus were imaged by micro-CT. The following were measured on images: cartilage volume (Cart.Vol, mm³) and thickness (Cart.Th, mm); SCP thickness (SCP.Th, μm) and porosity (SCP.Por, %); bone volume to total volume fraction (BV/TV, %); trabecular thickness (Tb.Th, μm), spacing (Tb.Sp, μm), and number (Tb.N, 1/mm); structure model index (SMI); trabecular pattern factor (Tb.Pf); and degree of anisotropy (DA).

Results

Among the 28 specimens studied (18 females) from individuals with mean age 82.8±10.2 years, cartilage and SCP were thicker at the central site uncovered by the meniscus than the posterior and peripheral sites, and Cart.Vol was greater. SCP.Por was highest in posterior samples. In the upper 1–5 mm of subchondral bone, central samples were characterized by higher values for BV/TV, Tb.N, Tb.Th, and connectivity (Tb.Pf), a more plate-like trabecular structure and lower anisotropy than with other samples. Deeper down, at 6–10 mm, the differences were slightly higher for Tb.Th centrally, DA peripherally and SMI posteriorly.

Conclusions

The coverage or not by meniscus in the knee of older individuals is significantly associated with Cart.Th, SCP.Th, SCP.Por and trabecular microarchitectural parameters in the most superficial 5 mm and to a lesser extent the deepest area of subchondral trabecular bone. These results suggest an effect of differences in local loading conditions. In subchondral bone uncovered by the meniscus, the trabecular architecture resembles that of highly loaded areas.

Large Animal Models of Meniscus Repair and Regeneration: A Systematic Review of the State of the Field

Injury to the meniscus is common, but few viable strategies exist for its repair or regeneration. To address this, animal models have been developed to translate new treatment strategies toward the clinic. However, there is not yet a regulatory document guiding such studies. The purpose of this study was to carry out a systematic review of the literature on meniscus treatment methods and outcomes to define the state of the field. Public databases were queried by using search terms related to animal models and meniscus injury and/or repair over the years 1980-2015. Identified peer-reviewed manuscripts were screened by using Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. One of nine reviewers read each manuscript and scored them based on whether the publication described a series of predefined study descriptors and outcome measures. Additional data were extracted to identify common assays used. A total of 128 full-length peer-reviewed manuscripts were identified. The number of publications increased over the time frame analyzed, with 48% focused on augmented repair. Rabbit was, by far, the most prevalent species utilized (46%), with dog (21%) and sheep (20%) being the next most common. Analysis of study descriptors revealed that most studies appropriately documented details of the animal used, the surgical approach, and defect and implant characteristics (e.g., 63% of studies identified clearly the defect size). In terms of outcome parameters, most studies carried out macroscopic (85%), histologic (90%), and healing/integration (83%) analyses of the meniscus. However, many studies did not provide further analysis beyond these fundamental measures, and less than 40% reported on the adjacent cartilage and synovium, as well as joint function. There is intense interest in the field of meniscus repair. However, given the current lack of guidance documentation in this area, preclinical animal models are not performed in a standardized fashion. The development of a "Best Practices" document would increase reproducibility and external validity of experiments, while accelerating advancements in translational research. Advancement is of paramount importance given the high prevalence of meniscal injuries and the paucity of effective repair or regenerative strategies.

Two-Tunnel Transtibial Repair of Radial Meniscus Tears Produces Comparable Results to Inside-Out Repair of Vertical Meniscus Tears

BACKGROUND

Radial meniscus tears disrupt the circumferential fibers and thereby compromise meniscus integrity. Historically, radial tears were often treated with meniscectomy because of an incomplete understanding of the biomechanical consequences of these tears, limited information regarding the biomechanical performance of repair, and the technical difficulty associated with repair. There is a paucity of studies on the outcomes of the repair of radial meniscus tears. Purpose/Hypothesis: The purpose was to determine the outcomes of 2-tunnel transtibial repair of radial meniscus tears and compare these results to the outcomes of patients who underwent the repair of vertical meniscus tears with a minimum of 2-year follow-up. The hypothesis was that radial and vertical meniscus tear repair outcomes were comparable.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Patients who underwent 2-tunnel transtibial pullout repair for a radial meniscus tear were included in this study and compared with patients who underwent inside-out repair for a vertical meniscus tear. Subjective questionnaires were administered preoperatively and at a minimum of 2-year follow-up, including the Lysholm score, the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), the Short Form-12 (SF-12) physical component summary (PCS), the Tegner activity scale, and patient satisfaction. Analysis of covariance was used to compare postoperative outcome scores between the meniscus repair groups while accounting for baseline scores. Adjusted mean effects relative to the radial repair group were reported with 95% CIs.

RESULTS

Twenty-seven patients who underwent 2-tunnel transtibial pullout repair for radial meniscus tears and 33 patients who underwent inside-out repair for vertical meniscus tears were available for follow-up at a mean of 3.5 years (range, 2.0-5.4 years). No preoperative outcome score significantly differed between the groups. There were no significant group differences for any of the 2-year postoperative outcome scores. Relative to the vertical repair group, the radial repair group exhibited an adjusted mean of -0.2 (95% CI, -5.4 to 4.9), -0.6 (95% CI, -6.6 to 5.5), and 5.1 (95% CI, -3.9 to 14.0) points on the SF-12 PCS, WOMAC, and Lysholm scores, respectively.

CONCLUSION

The 2-tunnel transtibial pullout technique for the repair of radial meniscus tears produces similar clinical outcomes when compared with the repair of vertical meniscus tears at a mean 3.5 years' follow-up.

Mechanical function near defects in an aligned nanofiber composite is preserved by inclusion of disorganized layers: Insight into meniscus structure and function

The meniscus is comprised of circumferentially aligned fibers that resist the tensile forces within the meniscus (i.e., hoop stress) that develop during loading of the knee. Although these circumferential fibers are severed by radial meniscal tears, tibial contact stresses do not increase until the tear reaches ∼90% of the meniscus width, suggesting that the severed circumferential fibers still bear load and maintain the mechanical functionality of the meniscus. Recent data demonstrates that the interfibrillar matrix can transfer strain energy to disconnected fibrils in tendon fascicles. In the meniscus, interdigitating radial tie fibers, which function to stabilize and bind the circumferential fibers together, are hypothesized to function in a similar manner by transmitting load to severed circumferential fibers near a radial tear. To test this hypothesis, we developed an engineered fibrous analog of the knee meniscus using poly(ε-caprolactone) to create aligned scaffolds with variable amounts of non-aligned elements embedded within the scaffold. We show that the tensile properties of these scaffolds are a function of the ratio of aligned to non-aligned elements, and change in a predictable fashion following a simple mixture model. When measuring the loss of mechanical function in scaffolds with a radial tear, compared to intact scaffolds, the decrease in apparent linear modulus was reduced in scaffolds containing non-aligned layers compared to purely aligned scaffolds. Increased strains in areas adjacent to the defect were also noted in composite scaffolds. These findings indicate that non-aligned (disorganized) elements interspersed within an aligned network can improve overall mechanical function by promoting strain transfer to nearby disconnected fibers. This finding supports the notion that radial tie fibers may similarly promote tear tolerance in the knee meniscus, and will direct changes in clinical practice and provide guidance for tissue engineering strategies.

STATEMENT OF SIGNIFICANCE

The meniscus is a complex fibrous tissue, whose architecture includes radial tie fibers that run perpendicular to and interdigitate with the predominant circumferential fibers. We hypothesized that these radial elements function to preserve mechanical function in the context of interruption of circumferential bundles, as would be the case in a meniscal tear. To test this hypothesis, we developed a biomaterial analog containing disorganized layers enmeshed regularly throughout an otherwise aligned network. Using this material formulation, we showed that strain transmission is improved in the vicinity of defects when disorganized fiber layers were present. This supports the idea that radial elements within the meniscus improve function near a tear, and will guide future clinical interventions and the development of engineered replacements.

A model system for developing a tissue engineered meniscal enthesis

The meniscus acts as a stabilizer, lubricator, and load distributer in the knee joint. The mechanical stability of the meniscus depends on its connection to the underlying bone by a fibrocartilage to bone transition zone called the meniscal enthesis. Tissue engineered menisci hold great promise as a treatment alternative however lack a means of integrated fixation to the underlying bone needed in order for a tissue engineered meniscal replacement to be successful. Tissue engineering the meniscal enthesis is a difficult task given the complex gradients of cell type, mineral, and extracellular matrix molecules. Therefore, there is a need for a simplified and high throughput enthesis model to test experimental parameters. The goal of this study was to develop a simplified enthesis model to test collagen integration with decellularized bone. We found that injection molding collagen into tubing loaded with decellularized bone plugs resulted in a scaffold with three regions: bone, bone-collagen, and collagen. Furthermore, collagen formation was directed in the axial direction by using mechanical fixation at the bony ends. The results of this study showed that this technique can be used to mimic the native enthesis morphology and serves as ideal test platform to generate a model tissue engineered enthesis.

STATEMENT OF SIGNIFICANCE

The meniscal enthesis is a complex structure that is essential to mechanical stability of the meniscus and the knee joint. Several studies document the development of anatomically shaped tissue engineered meniscus constructs, but none have focused on how to integrate such tissues with underlying bone. This study establishes a simplified construct to model the meniscal enthesis composed of a collagen gel seeded with meniscal fibrochondrocytes integrated with decellularized cancellous bone. Mechanical fixation at the bony ends induced tissue integration of fibers into the bony tissue, which is critical for mechanical performance and has yet to be shown in enthesis literature. Our test platform is amenable to targeted experiments investigating mineralization gradients, collagen fiber alignment, cell population phenotype, and media conditioning with experimental impact on enthesis studies for meniscus, tendon, and ligament.

Medial tibial plateau morphology and stress fracture location: A magnetic resonance imaging study

AIM

To determine the location of medial tibial plateau stress fractures and its relationship with tibial plateau morphology using magnetic resonance imaging (MRI).

METHODS

A retrospective review of patients with a diagnosis of stress fracture of the medial tibial plateau was performed for a 5-year period. Fourteen patients [three female and 11 male, with an average age of 36.4 years (range, 15-50 years)], who underwent knee MRI, were included. The appearance of the tibial plateau stress fracture and the geometry of the tibial plateau were reviewed and measured on MRI.

RESULTS

Thirteen of 14 stress fractures were linear, and one of them stellated on MRI images. The location of fractures was classified into three types. Three fractures were located anteromedially (AM type), six posteromedially (PM type), and five posteriorly (P type) at the medial tibial plateau. In addition, tibial posterior slope at the medial tibial plateau tended to be larger when the fracture was located more posteriorly on MRI.

CONCLUSION

We found that MRI showed three different localizations of medial tibial plateau stress fractures, which were associated with tibial posterior slope at the medial tibial plateau.

Changes in Contact Area in Meniscus Horizontal Cleavage Tears Subjected to Repair and Resection

PURPOSE

To assess the changes in tibiofemoral contact pressure and contact area in human knees with a horizontal cleavage tear before and after treatment.

METHODS

Ten human cadaveric knees were tested. Pressure sensors were placed under the medial meniscus and the knees were loaded at twice the body weight for 20 cycles at 0°, 10°, and 20° of flexion. Contact area and pressure were recorded for the intact meniscus, the meniscus with a horizontal cleavage tear, after meniscal repair, after partial meniscectomy (single leaflet), and after subtotal meniscectomy (double leaflet).

RESULTS

The presence of a horizontal cleavage tear significantly increased average peak contact pressure and reduced effective average tibiofemoral contact area at all flexion angles tested compared with the intact state (P < .03). There was approximately a 70% increase in contact pressure after creation of the horizontal cleavage tear. Repairing the horizontal cleavage tear restored peak contact pressures and areas to within 15% of baseline, statistically similar to the intact state at all angles tested (P < .05). Partial meniscectomy and subtotal meniscectomy significantly increased average peak contact pressure and reduced average contact area at all degrees of flexion compared with the intact state (P < .05).

CONCLUSIONS

The presence of a horizontal cleavage tear in the medial meniscus causes a significant reduction in contact area and a significant elevation in contact pressure. These changes may accelerate joint degeneration. A suture-based repair of these horizontal cleavage tears returns the contact area and contact pressure to nearly normal, whereas both partial and subtotal meniscectomy lead to significant reductions in contact area and significant elevations in contact pressure within the knee. Repairing horizontal cleavage tears may lead to improved clinical outcomes by preserving meniscal tissue and the meniscal function.

CLINICAL RELEVANCE

Understanding contact area and peak contact pressure resulting from differing strategies for treating horizontal cleavage tears will allow the surgeon to evaluate the best strategy for treating his or her patients who present with this meniscal pathology.

Clinical platform for understanding the relationship between joint contact mechanics and articular cartilage changes after meniscal surgery

Injury to the meniscus of the knee has been implicated as a significant risk factor for the subsequent development of osteoarthritis, but the mechanisms of joint degeneration are unclear. Our objective was to develop a clinically applicable methodology to evaluate the relationship of joint contact mechanics at the time of surgery to biological changes of articular cartilage as a function of time following surgery. A series of pre-, intra-, and post-operative protocols were developed which utilized electronic sensors for the direct measurement of contact mechanics, and advanced imaging to assess cartilage health. The tests were applied to a pilot cohort of young active patients undergoing meniscus allograft transplantation. Our study demonstrated significant variability across patients in terms of contact area and peak contact stress, both before and after transplantation. Nonetheless, the majority of patients exhibited decreased peak contact stress and increased contact area after graft implantation. MR scans at 3-6 months showed decreased T1ρ values in tibial articular cartilage, suggesting an increase in proteoglycan content or concomitant decrease in water content. Prolongation of T2 values was found primarily within the central, cartilage-cartilage contact region of the tibial plateau suggested disruption of the collagen network. Minimal differences were found in cartilage thickness over the short time frame of this preliminary study. With longer clinical follow-up, our platform of clinical tests can be used to better understand the patient-specific mechanical factors that are related to increased risk of OA after meniscus injury and surgery. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:600-611, 2017.

High meniscal slope angle as a risk factor for meniscal allograft extrusion

A meniscal graft extrusion is still an unresolved problem that affects most patients after a meniscal transplantation. Despite the advances in surgical techniques, together with the improved methods for a meniscal allograft sizing, success is only observed in up to 75% of patients after they experience a meniscal allograft transplantation. Because a meniscal extrusion is associated with a cartilage deterioration and the progression of osteoarthritis there is a great interest in how to prevent this phenomenon. The crucial factor for the minimisation of a meniscal allograft extrusion is by perfectly matching the implant. Most methods for a meniscal allograft sizing only focus on assessing the length and the width of the meniscus. Even though there is some evidence that there is a relationship between the shape of the meniscus in a cross-sectional plane and the meniscal extrusion, any of the planning methods do not take this factor into consideration. Although there is a large variability of meniscus shapes in cross-section, we hypothesise that by taking the meniscal slope into account during surgical planning, as well as performing the correct adjustments of this particular parameter, we can diminish the risk of a meniscal allograft extrusion.

Kinematics of meniscal- and ACL-transected mouse knees during controlled tibial compressive loading captured using roentgen stereophotogrammetry

Pre-clinical studies of post-traumatic OA have examined the pathways that lead to disease after injury by using surgical models such as the destabilization of the medial meniscus (DMM) and anterior cruciate ligament transection (ACLT). While the morphological, molecular, and genetic pathways leading to OA have been examined extensively; the effects of these injuries on joint kinematics, and thus disease progression, have yet to be fully characterized. To this end, we sought to understand the kinematics in the DMM and ACLT joints compared to intact joints subjected to controlled tibial compressive loading. We hypothesized that the DMM and ACLT models would result in different patterns of joint instability compared to intact joints, thus explaining the different patterns of OA initiation and severity in these models. Cadaver adult C57BL/6 mice were subjected to either a DMM or ACLT in their right knee joints, while the left limbs remained as intact controls. All limbs were labeled with fiducial markers, and the rigid body kinematics of the tibia and femur were examined using roentgen stereophotogrammetry (RSA) with application of compressive loads from 0 to 9 N. DMM and intact joints demonstrated similar kinematics under compressive loading, in contrast to ACLT joints, which dislocated even before load application. These results demonstrate the importance of rigorous kinematic analysis in defining the role of joint instability in animal models of OA and suggest significant differences in DMM and ACLT joint instabilities in the context of controlled mechanical loading. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:353-360, 2017.

Fiber development and matrix production in tissue-engineered menisci using bovine mesenchymal stem cells and fibrochondrocytes

Mesenchymal stem cells (MSCs) have been investigated with promising results for meniscus healing and tissue engineering. While MSCs are known to contribute to extracellular matrix (ECM) production, less is known about how MSCs produce and align large organized fibers for application to tissue engineering the meniscus. The goal of this study was to investigate the capability of MSCs to produce and organize ECM molecules compared to meniscal fibrochondrocytes (FCCs). Bovine FCCs and MSCs were encapsulated in an anatomically accurate collagen meniscus using monoculture and co-culture of each cell type. Each meniscus was mechanically anchored at the horns to mimic the physiological fixation by the meniscal entheses. Mechanical fixation generates a static mechanical boundary condition previously shown to induce formation of oriented fiber by FCCs. Samples were cultured for 4 weeks and then evaluated for biochemical composition and fiber development. MSCs increased the glycosaminoglycan (GAG) and collagen production in both co-culture and monoculture groups compared to FCC monoculture. Collagen organization was greatest in the FCC monoculture group. While MSCs had increased matrix production, they lacked the fiber organization capabilities of FCCs. This study suggests that GAG production and fiber formation are linked. Co-culture can be used as a means of balancing the synthetic properties of MSCs and the matrix remodeling capabilities of FCCs for tissue engineering applications.

Tibiofemoral Contact Mechanics with Horizontal Cleavage Tear and Resection of the Medial Meniscus in the Human Knee

BACKGROUND

The meniscus is known to increase the contact area and decrease contact pressure in the tibiofemoral compartments of the knee. Radial tears of the meniscal root attachment along with partial resections of the torn meniscal tissue decrease the contact area and increase pressure; however, there is a lack of information on the effects of a horizontal cleavage tear (HCT) and partial leaf meniscectomy of such tears on tibiofemoral contact pressure and contact area.

METHODS

Twelve fresh-frozen human cadaveric knees were tested under 10 conditions: 5 serial conditions of posterior medial meniscectomy (intact meniscus, HCT, repaired HCT, inferior leaf resection, and resection of both inferior and superior leaves), each at 2 knee flexion angles (0° and 60°) under an 800-N axial load. Tekscan sensors (model 4000) were used to measure the contact pressure and contact area.

RESULTS

HCT and HCT repair resulted in small changes in the contact area and an increase in contact pressure compared with the intact condition. Resection of the inferior leaf resulted in significantly decreased contact area (to a mean 82.3% of the intact condition at 0° of flexion and 81.8% at 60° of flexion; p < 0.05) and increased peak contact pressure (a mean 36.3% increase at 0° flexion and 43.2% increase at 60° flexion; p < 0.05) in the medial compartment. Further resection of the remaining superior leaf resulted in additional significant decreases in contact area (to a mean 60.1% of the intact condition at 0° of flexion and 49.7% at 60° of flexion; p < 0.05) and increases in peak contact pressure (a mean 79.2% increase at 0° of flexion and 74.9% increase at 60° of flexion; p < 0.05).

CONCLUSIONS

Resection of meniscal tissue forming the inferior leaf of an HCT resulted in substantially decreased contact area and increased contact pressure. Additional resection of the superior leaf resulted in a further significant decrease in contact area and increase in contact pressure in the medial compartment.

CLINICAL RELEVANCE

Repair or minimal resection of meniscal tissue of an HCT may be preferred to complete leaf resection to maintain knee tibiofemoral contact mechanics.

Surgical Techniques and Outcomes of Repairing Meniscal Radial Tears: A Systematic Review

PURPOSE

To systematically review meniscal radial tear repair procedures and compare the techniques, outcomes, and complications.

METHODS

Studies were identified through a systematic review of the literature using the Cochrane Database of Systematic Reviews, the Cochrane Central Register of Controlled Trials, PubMed (1980-2014), Medline (1980-2014), and Embase. Inclusion criteria included a minimum follow-up of 24 months, English language, and publications from 1980 or later. Exclusion criteria were surgical techniques not reporting follow-up, biomechanical studies, cadaver/anatomic studies, and non-radial tear meniscal repair procedures. Meniscal radial repair, meniscal radial tear, meniscal radial tear repair, radial repair and radial tear were used as search terms.

RESULTS

A total of 6 studies (55 patients) met the inclusion criteria. The mean duration of follow-up ranged from 24 to 71 months. Of the 6 studies, 5 reported radial tears to the lateral meniscus and 1 study reported cases of both medial and lateral meniscal radial tears. Two studies reported different inside-out repair techniques, 2 studies reported the use of an all-inside anchor-based repair system, 1 study reported an all-inside repair technique with absorbable sutures, and 1 study reported an inside-out repair with fibrin clots. Average postoperative Lysholm scores were reported in all 6 studies and ranged from 86.9 to 95.6. Average postoperative Tegner activity scores were reported in 4 studies and ranged from 1 to 6.7. The majority of studies concluded that their techniques produced satisfactory healing of the radial tear, without serious subsequent complications.

CONCLUSIONS

Radial repair techniques differed among studies; however, postoperative subjective outcomes revealed patient improvement with repairing radial tears. With the increasing concern of long-term osteoarthritis after meniscectomy, meniscal preservation with repair of radial tears results in improved short-term clinical outcomes; however, long-term outcomes remain unknown.

LEVEL OF EVIDENCE

Level IV, systematic review of level IV studies.

Medial Meniscus Radial Tear: A Transtibial 2-Tunnel Technique

Complete radial tears of the medial meniscus significantly decrease the meniscal tissue's ability to dissipate tibiofemoral loads and have been described as functionally similar to a total meniscectomy, predisposing patients to early osteoarthritis. At present, no consensus exists regarding the optimal surgical treatment of a radial meniscal tear. Current repair techniques have led to a reportedly high rate of incomplete healing or healing of the meniscus in a nonanatomic, gapped position, which compromises its ability to withstand hoop stresses. Improvement regarding the ability to repair and heal medial meniscus radial tears has the potential to result in enhanced preservation of the articular cartilage in the medial compartment of the knee. This technical description details a method for repairing radial tears of the medial meniscus using a transtibial 2-tunnel technique.

The cost-effectiveness of meniscal repair versus partial meniscectomy: A model-based projection for the United States

BACKGROUND

Meniscal tears are the most common knee condition requiring surgery, and represent a substantial disease burden with clinical and cost implications. The success rates partial meniscectomy and meniscal repair have been studied, but limited information is available investigating their long-term costs and effects. Our objective was to assess the long-term cost-effectiveness of meniscal repair compared to meniscectomy.

METHODS

We constructed a decision-analytic Markov disease progression model, using strategy-specific failure rates and treatment-specific probabilities for the development of osteoarthritis (OA) and subsequent knee replacement (TKR). Failure rates and OA incidence were derived from controlled and uncontrolled studies as well as meta-analyses. Costs were derived from 2014U.S. reimbursement amounts and published literature.

RESULTS

Meniscal repair was associated with an increased failure rate (RR of 4.37), but meaningful reductions in OA and TKR incidence (29.7% vs. 39.4% and 19.6% vs. 27.9%, respectively) in our model-based analysis. Over the 30-year horizon, meniscal repair was associated with an increase in discounted QALYs to 16.52 (compared to 16.37 QALYs for meniscectomy), at overall discounted savings of $2384, making it the dominant index procedure strategy. Using age-specific per-patient cost and QALYs projected for the 30-year horizon, our computations suggest that payers could save approximately $43 million annually if 10% of current meniscectomies could be performed as meniscal repairs.

CONCLUSIONS

Our projection suggests that meniscal repair, despite substantially higher failure rates, is associated with improved long-term outcomes and cost savings relative to meniscectomy in the majority of patients, making it the dominant treatment strategy.

Relationship between meniscal integrity and risk factors for cartilage degeneration

BACKGROUND

The purpose of this study was to use MRI to determine if a loss of meniscal intra-substance integrity, as determined by T2* relaxation time, is associated with an increase of Kellgren-Lawrence (KL) grade, and if this was correlated with risk factors for cartilage degeneration, namely meniscal extrusion, contact area and anterior-posterior (AP) displacement.

METHODS

Eleven symptomatic knees with a KL 2 to 4 and 11 control knees with a KL 0 to 1 were studied. A 3 Tesla MRI scanner was used to scan all knees at 15° of flexion. With a 222N compression applied, a 3D SPACE sequence was obtained, followed by a spin echo 3D T2* mapping sequence. Next, an internal tibial torque of 5Nm was added and a second 3D SPACE sequence obtained. The MRI scans were post-processed to evaluate meniscal extrusion, contact area, AP displacement and T2* relaxation time.

RESULTS

KL grade was correlated with T2* relaxation time for both the anterior medial meniscus (r=0.79, p<0.001) and the posterior lateral meniscus (r=0.55, p=0.009). In addition, T2* relaxation time was found to be correlated with risk factors for cartilage degeneration. The largest increases in meniscal extrusion and decreases in contact area were noted for those with meniscal tears (KL 3 to 4). All patients with KL 3 to 4 indicated evidence of meniscal tears.

CONCLUSIONS

This suggests that a loss of meniscal integrity, in the form of intra-substance degeneration, is correlated with risk factors for cartilage degeneration.

A Novel Repair Method for Radial Tears of the Medial Meniscus: Biomechanical Comparison of Transtibial 2-Tunnel and Double Horizontal Mattress Suture Techniques Under Cyclic Loading

BACKGROUND

Complete radial tears of the medial meniscus have been reported to be functionally similar to a total meniscectomy. At present, there is no consensus on an ideal technique for repair of radial midbody tears of the medial meniscus. Prior attempts at repair with double horizontal mattress suture techniques have led to a reportedly high rate of incomplete healing or healing in a nonanatomic (gapped) position, which compromises the ability of the meniscus to withstand hoop stresses.

HYPOTHESIS

A newly proposed 2-tunnel radial meniscal repair method will result in decreased gapping and increased ultimate failure loads compared with the double horizontal mattress suture repair technique under cyclic loading.

STUDY DESIGN

Controlled laboratory study.

METHODS

Ten matched pairs of male human cadaveric knees (average age, 58.6 years; range, 48-66 years) were used. A complete radial medial meniscal tear was made at the junction of the posterior one-third and middle third of the meniscus. One knee underwent a horizontal mattress inside-out repair, while the contralateral knee underwent a radial meniscal repair entailing the same technique with a concurrent novel 2-tunnel repair. Specimens were potted and mounted on a universal testing machine. Each specimen was cyclically loaded 1000 times with loads between 5 and 20 N before experiencing a load to failure. Gap distances at the tear site and failure load were measured.

RESULTS

The 2-tunnel repairs exhibited a significantly stronger ultimate failure load (median, 196 N; range, 163-212 N) than did the double horizontal mattress suture repairs (median, 106 N; range, 63-229 N) (P = .004). In addition, the 2-tunnel repairs demonstrated decreased gapping at all testing states (P < .05) with a final measured gapping of 1.7 mm and 4.1 mm after 1000 cycles for the 2-tunnel and double horizontal mattress suture repairs, respectively.

CONCLUSION

The 2-tunnel repairs displayed significantly less gapping distance after cyclic loading and had significantly stronger ultimate failure loads compared with the double horizontal mattress suture repairs.

CLINICAL RELEVANCE

Complete radial tears of the medial meniscus significantly decrease the ability of the meniscus to dissipate tibiofemoral loads, predisposing patients to early osteoarthritis. Improving the ability to repair medial meniscal radial tears in a way that withstands cyclic loads and heals in an anatomic position could significantly improve patient healing rates and result in improved preservation of the articular cartilage of the medial compartment of the knee. The 2-tunnel repair may be a more reliable and stronger repair option for midbody radial tears of the medial meniscus. Clinical studies are warranted to further evaluate these repairs.

Zonal differences in meniscus MR relaxation times in response to in vivo static loading in knee osteoarthritis

This study assessed the effects of static loading on MRI relaxation times of menisci in individuals with and without radiographic knee OA. High-resolution fast spin-echo (FSE) and T(1ρ)/T(2) relaxation time MR sequences were obtained with and without loading at 50% body weight in 124 subjects. T(1ρ)/T(2) relaxation times were calculated in menisci, and meniscus lesions were assessed through clinical grading. Student's t-test compared OA and control unloaded relaxation times as well as within-group changes with loading, Generalized Linear Models evaluated zonal variation, and ANCOVA compared loading response between groups. Unloaded T(1ρ) and T(2) in the middle and inner zones of the lateral anterior horn and outer zone of the medial posterior horn were significantly higher in OA and suggest that meniscal OA change occurs unevenly. Zonal T(1ρ) and T(2) showed differing patterns between anterior and posterior horns, suggesting differences in macromolecular organization. Significant increases with loading were seen largely in the T(2) of controls and less frequently in subjects with OA. In the medial posterior horn, T(1ρ) and T(2) decreased with loading in OA but changed negligibly in controls; these significantly different loading responses between groups may indicate load transmission failure in OA menisci.

Cost-effectiveness analysis of arthroscopic surgery compared with non-operative management for osteoarthritis of the knee

OBJECTIVE

To determine the cost-effectiveness of arthroscopic surgery in addition to non-operative treatments compared with non-operative treatments alone in patients with knee osteoarthritis (OA).

DESIGN, SETTING AND PARTICIPANTS

We conducted an economic evaluation alongside a single-centre, randomised trial among patients with symptomatic, radiographic knee OA (KL grade ≥ 2).

INTERVENTIONS

Patients received arthroscopic debridement and partial resection of degenerative knee tissues in addition to optimised non-operative therapy, or optimised non-operative therapy only.

MAIN OUTCOME MEASURES

Direct and indirect costs were collected prospectively over the 2-year study period. The effectiveness outcomes were the Western Ontario McMaster Osteoarthritis Index (WOMAC) and quality-adjusted life years (QALYs). Cost-effectiveness was estimated using the net benefit regression framework considering a range of willingness-to-pay values from the Canadian public payer and societal perspectives. We calculated incremental cost-effectiveness ratios and conducted sensitivity analyses using the extremes of the 95% CIs surrounding mean differences in effect between groups.

RESULTS

168 patients were included. Patients allocated to arthroscopy received partial resection and debridement of degenerative meniscal tears (81%) and/or articular cartilage (97%). There were no significant differences between groups in use of non-operative treatments. The incremental net benefit was negative for all willingness-to-pay values. Uncertainty estimates suggest that even if willing to pay $400,000 to achieve a clinically important improvement in WOMAC score, or ≥$50,000 for an additional QALY, there is <20% probability that the addition of arthroscopy is cost-effective compared with non-operative therapies only. Our sensitivity analysis suggests that even when assuming the largest treatment effect, the addition of arthroscopic surgery is not economically attractive compared with non-operative treatments only.

CONCLUSIONS

Arthroscopic debridement of degenerative articular cartilage and resection of degenerative meniscal tears in addition to non-operative treatments for knee OA is not an economically attractive treatment option compared with non-operative treatment only, regardless of willingness-to-pay value.

TRIAL REGISTRATION NUMBER

NCT00158431.

Patellar taping alters knee kinematics during step descent in individuals with a meniscal injury: An exploratory study

BACKGROUND

Meniscus lesions are common musculoskeletal knee injuries which often lead to pain, limitation and compensations during functional tasks, such as descending stairs. This study investigated the effect of patellar taping with tension and without tension on three-dimensional (3D) kinematics of the knee during a slow step descent task in patients with meniscal lesions.

METHODS

Ten patients diagnosed with a meniscal lesion, confirmed by magnetic resonance imaging, underwent five, step descent movements at slow speed under three different conditions: 1) no taping; 2) tension-free taping; and 3) patellar taping with medial tension. 3D kinematic data were recorded from the injured knee using an eight-camera infrared Vicon motion analysis system. Maximum and minimum angle values and total range of motion (maximum/minimum value) in three movement planes during single-limb stance were compared using a repeated measure ANOVA.

FINDINGS

Results showed a significant increase in the maximum and minimum angle value in the sagittal plane (mean differences=2.4° and 4.2°, respectively) and a decrease in the transverse plane (-6.3° and -2.2°, respectively) for the patellar taping condition compared to the no taping condition. A decreased rotational angle range when comparing the patellar taping to the no taping (-4.1°) and tension-free taping (-3.1°) conditions was also observed. These changes remained significant when pain was considered as a covariate in the analysis. The tension applied to the patellar tape played a role in controlling the sagittal and transverse plane step-down movement among patients in our study.

INTERPRETATION

These results support the use of patellar taping with a medially oriented tension to help to reduce the transversal plane movement of the knee in this population and they bring new light to the taping effect.

Three dimensional patient-specific collagen architecture modulates cartilage responses in the knee joint during gait

Site-specific variation of collagen fibril orientations can affect cartilage stresses in knee joints. However, this has not been confirmed by 3-D analyses. Therefore, we present a novel method for evaluation of the effect of patient-specific collagen architecture on time-dependent mechanical responses of knee joint cartilage during gait. 3-D finite element (FE) models of a human knee joint were created with the collagen architectures obtained from T2 mapped MRI (patient-specific model) and from literature (literature model). The effect of accuracy of the implementation of collagen fibril architecture into the model was examined by using a submodel with denser FE mesh. Compared to the literature model, fibril strains and maximum principal stresses were reduced especially in the superficial/middle regions of medial tibial cartilage in the patient-specific model after the loading response of gait (up to -413 and -26%, respectively). Compared to the more coarsely meshed joint model, the patient-specific submodel demonstrated similar strain and stress distributions but increased values particularly in the superficial cartilage regions (especially stresses increased >60%). The results demonstrate that implementation of subject-specific collagen architecture of cartilage in 3-D modulates location- and time-dependent mechanical responses of human knee joint cartilage. Submodeling with more accurate implementation of collagen fibril architecture alters cartilage stresses particularly in the superficial/middle tissue.

A comparison of stress in cracked fibrous tissue specimens with varied crack location, loading, and orientation using finite element analysis

Cracks in fibrous soft tissue, such as intervertebral disc annulus fibrosus and knee meniscus, cause pain and compromise joint mechanics. A crack concentrates stress at its tip, making further failure and crack extension (fracture) more likely. Ex vivo mechanical testing is an important tool for studying the loading conditions required for crack extension, but prior work has shown that it is difficult to reproduce crack extension. Most prior work used edge crack specimens in uniaxial tension, with the crack 90° to the edge of the specimen. This configuration does not necessarily represent the loading conditions that cause in vivo crack extension. To find a potentially better choice for experiments aiming to reproduce crack extension, we used finite element analysis to compare, in factorial combination, (1) center crack vs. edge crack location, (2) biaxial vs. uniaxial loading, and (3) crack-fiber angles ranging from 0° to 90°. The simulated material was annulus fibrosus fibrocartilage with a single fiber family. We hypothesized that one of the simulated test cases would produce a stronger stress concentration than the commonly used uniaxially loaded 90° crack-fiber angle edge crack case. Stress concentrations were compared between cases in terms of fiber-parallel stress (representing risk of fiber rupture), fiber-perpendicular stress (representing risk of matrix rupture), and fiber shear stress (representing risk of fiber sliding). Fiber-perpendicular stress and fiber shear stress concentrations were greatest in edge crack specimens (of any crack-fiber angle) and center crack specimens with a 90° crack-fiber angle. However, unless the crack is parallel to the fiber direction, these stress components alone are insufficient to cause crack opening and extension. Fiber-parallel stress concentrations were greatest in center crack specimens with a 45° crack-fiber angle, either biaxially or uniaxially loaded. We therefore recommend that the 45° center crack case be tried in future experiments intended to study crack extension by fiber rupture.

Strategies for the prevention of knee osteoarthritis

Osteoarthritis (OA) has been thought of as a disease of cartilage that can be effectively treated surgically at severe stages with joint arthroplasty. Today, OA is considered a whole-organ disease that is amenable to prevention and treatment at early stages. OA develops slowly over 10-15 years, interfering with activities of daily living and the ability to work. Many patients tolerate pain, and many health-care providers accept pain and disability as inevitable corollaries of OA and ageing. Too often, health-care providers passively await final 'joint death', necessitating knee and hip replacements. Instead, OA should be viewed as a chronic condition, where prevention and early comprehensive-care models are the accepted norm, as is the case with other chronic diseases. Joint injury, obesity and impaired muscle function are modifiable risk factors amenable to primary and secondary prevention strategies. The strategies that are most appropriate for each patient should be identified, by selecting interventions to correct--or at least attenuate--OA risk factors. We must also choose the interventions that are most likely to be acceptable to patients, to maximize adherence to--and persistence with--the regimes. Now is the time to begin the era of personalized prevention for knee OA.

Arthroscopic surgery for degenerative knee: systematic review and meta-analysis of benefits and harms

OBJECTIVE

To determine benefits and harms of arthroscopic knee surgery involving partial meniscectomy, debridement, or both for middle aged or older patients with knee pain and degenerative knee disease.

DESIGN

Systematic review and meta-analysis.

MAIN OUTCOME MEASURES

Pain and physical function.

DATA SOURCES

Systematic searches for benefits and harms were carried out in Medline, Embase, CINAHL, Web of Science, and the Cochrane Central Register of Controlled Trials (CENTRAL) up to August 2014. Only studies published in 2000 or later were included for harms.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

Randomised controlled trials assessing benefit of arthroscopic surgery involving partial meniscectomy, debridement, or both for patients with or without radiographic signs of osteoarthritis were included. For harms, cohort studies, register based studies, and case series were also allowed.

RESULTS

The search identified nine trials assessing the benefits of knee arthroscopic surgery in middle aged and older patients with knee pain and degenerative knee disease. The main analysis, combining the primary endpoints of the individual trials from three to 24 months postoperatively, showed a small difference in favour of interventions including arthroscopic surgery compared with control treatments for pain (effect size 0.14, 95% confidence interval 0.03 to 0.26). This difference corresponds to a benefit of 2.4 (95% confidence interval 0.4 to 4.3) mm on a 0-100 mm visual analogue scale. When analysed over time of follow-up, interventions including arthroscopy showed a small benefit of 3-5 mm for pain at three and six months but not later up to 24 months. No significant benefit on physical function was found (effect size 0.09, -0.05 to 0.24). Nine studies reporting on harms were identified. Harms included symptomatic deep venous thrombosis (4.13 (95% confidence interval 1.78 to 9.60) events per 1000 procedures), pulmonary embolism, infection, and death.

CONCLUSIONS

The small inconsequential benefit seen from interventions that include arthroscopy for the degenerative knee is limited in time and absent at one to two years after surgery. Knee arthroscopy is associated with harms. Taken together, these findings do not support the practise of arthroscopic surgery for middle aged or older patients with knee pain with or without signs of osteoarthritis.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42014009145.

Tibiofemoral contact pressures in radial tears of the meniscus treated with all-inside repair, inside-out repair and partial meniscectomy

BACKGROUND

To test contact pressures in the knee after treatment of a radial meniscus tear with an all-inside meniscal repair technique and compare the results with inside-out repair and partial meniscectomy.

METHODS

Six non-paired cadaveric knees were analyzed with intra-compartment pressures measured at loads of 250 N, 500 N and 1000 N at 0°, eight degrees, 15°, and 30° of knee flexion. Compartmental contact pressures were measured for the intact medial meniscus, radial tear in the posterior horn, all-inside repair using the NovoStitch suture passer device (Ceterix Orthopaedics Inc., Menlo Park, CA), inside-out repair method, and partial meniscectomy. One-way ANOVA was used for statistical analysis.

RESULTS

The greatest differences in peak pressures between treatments were observed under 1000 N load at 30° flexion (0.8± (SD) 0.1 MPa (intact meniscus), 0.8± (SD) 0.1 MPa (all-inside), 0.9± (SD) 0.1 MPa (inside-out) and 1.6± (SD) 0.2 MPa (partial meniscectomy)). Treatment with partial meniscectomy resulted in the highest peak pressures compared to all other states (p<0.0001 at each angle). Repair of the radial tear using the all-inside technique as well as the inside-out technique resulted in significantly decreased compartment pressures compared to partial meniscectomies (p<0.0001 at each angle). There were no significant differences between peak pressures in the intact state and after repair with the all-inside or inside-out techniques.

CONCLUSION

An all-inside repair technique using the NovoStitch suture passer can decrease contact pressures for a radial meniscus tear similarly to the inside-out repair technique when compared to partial meniscectomy.

CLINICAL RELEVANCE

This novel arthroscopic suture passer warrants further analysis in the clinical setting as it may be a reliable method for repair of radial meniscal tears through an arthroscopic all-inside technique.

Computational investigation of the time-dependent contact behaviour of the human tibiofemoral joint under body weight

The knee joint is one of the most common sites for osteoarthritis, the onset and progression of which are believed to relate to the mechanical environment of cartilage. To understand this environment, it is necessary to take into account the complex biphasic contact interactions of the cartilage and menisci. In this study, the time-dependent contact behaviour of an intact and a meniscectomized human tibiofemoral joint was characterized under body weight using a computational model. Good agreement in the contact area and femoral displacement under static loads were found between model predictions of this study and published experimental measurements. The time-dependent results indicated that as loading time progressed, the contact area and femoral vertical displacement of both intact and meniscectomized joints increased. More load was transferred to the cartilage-cartilage interface over time. However, the portions of load borne by the lateral and medial compartments did not greatly vary with time. Additionally, during the whole simulation period, the maximum compressive stress in the meniscectomized joint was higher than that in the intact joint. The fluid pressure in the intact and meniscectomized joints remained remarkably high at the condyle centres, but the fluid pressure at the cartilage-meniscus interface decreased faster than that at the condyle centres as loading time progressed. The above findings provide further insights into the mechanical environment of the cartilage and meniscus within the human knee joint.

Biomechanical comparison of arthroscopic repair constructs for radial tears of the meniscus

BACKGROUND

Radial tears of the meniscus represent a challenging clinical scenario because benign neglect and partial meniscectomy have both been shown to have negative biomechanical and long-term clinical consequences.

HYPOTHESIS

Complex suture repair constructs have higher failure loads and stiffness values compared with simple constructs.

STUDY DESIGN

Controlled laboratory study.

METHODS

After radial transection of human cadaveric menisci, simulated tears were repaired arthroscopically by use of 1 of 4 repair constructs: (1) 2 inside-out horizontal sutures, (2) 2 all-inside horizontal sutures, (3) an all-inside Mason-Allen construct consisting of 4 sutures, or (4) an all-inside construct consisting of a figure-of-8 suture plus 1 horizontal suture. Meniscus specimens were harvested and tested to failure on an Instron machine. The Kruskal-Wallis test was used to evaluate for significance of maximal failure load and stiffness between groups.

RESULTS

The mean maximum failure loads were 64 ± 20 N (inside-out horizontal construct), 75 ± 16 N (all-inside horizontal construct), 86 ± 19 N (Mason-Allen construct), and 113 ± 22 N (figure-of-8 plus horizontal construct). Interconstruct comparison revealed a statistically significant difference between the figure-of-8 plus horizontal construct and all 3 remaining constructs (P < .02) as well as the Mason-Allen construct when compared with the inside-out horizontal construct (P < .01). Statistical significance was not found between the all-inside horizontal construct and the Mason-Allen construct or between the all-inside horizontal construct and the inside-out horizontal construct (P = .2 and .7, respectively). Stiffness values were lower for the inside-out construct compared with the all-inside constructs (P < .05).

CONCLUSION

Complex all-inside repair constructs had significantly higher failure loads than a conventional, simple inside-out suture repair construct for repair of radial meniscal tears. Stiffness values among the all-inside groups were greater than those for the inside-out group.

CLINICAL RELEVANCE

Arthroscopic techniques are presented to produce stronger radial meniscal tear repairs.

Arthroscopic surgery for degenerative knee: systematic review and meta-analysis of benefits and harms

OBJECTIVE

To determine benefits and harms of arthroscopic knee surgery involving partial meniscectomy, debridement, or both for middle aged or older patients with knee pain and degenerative knee disease.

DESIGN

Systematic review and meta-analysis.

MAIN OUTCOME MEASURES

Pain and physical function.

DATA SOURCES

Systematic searches for benefits and harms were carried out in Medline, Embase, CINAHL, Web of Science, and the Cochrane Central Register of Controlled Trials (CENTRAL) up to August 2014. Only studies published in 2000 or later were included for harms.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

Randomised controlled trials assessing benefit of arthroscopic surgery involving partial meniscectomy, debridement, or both for patients with or without radiographic signs of osteoarthritis were included. For harms, cohort studies, register based studies, and case series were also allowed.

RESULTS

The search identified nine trials assessing the benefits of knee arthroscopic surgery in middle aged and older patients with knee pain and degenerative knee disease. The main analysis, combining the primary endpoints of the individual trials from three to 24 months postoperatively, showed a small difference in favour of interventions including arthroscopic surgery compared with control treatments for pain (effect size 0.14, 95% confidence interval 0.03 to 0.26). This difference corresponds to a benefit of 2.4 (95% confidence interval 0.4 to 4.3) mm on a 0-100 mm visual analogue scale. When analysed over time of follow-up, interventions including arthroscopy showed a small benefit of 3-5 mm for pain at three and six months but not later up to 24 months. No significant benefit on physical function was found (effect size 0.09, -0.05 to 0.24). Nine studies reporting on harms were identified. Harms included symptomatic deep venous thrombosis (4.13 (95% confidence interval 1.78 to 9.60) events per 1000 procedures), pulmonary embolism, infection, and death.

CONCLUSIONS

The small inconsequential benefit seen from interventions that include arthroscopy for the degenerative knee is limited in time and absent at one to two years after surgery. Knee arthroscopy is associated with harms. Taken together, these findings do not support the practise of arthroscopic surgery for middle aged or older patients with knee pain with or without signs of osteoarthritis.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42014009145.

Alterations in knee kinematics after partial medial meniscectomy are activity dependent

BACKGROUND

Alterations in knee kinematics after partial meniscectomy have been linked to the increased risk of osteoarthritis in this population. Understanding differences in kinematics during static versus dynamic activities of increased demand can provide important information regarding the possible underlying mechanisms of these alterations.

HYPOTHESIS

Differences in the following 2 kinematics measures will increase with activity demand: (1) the offset toward external tibial rotation for the meniscectomized limb compared with the contralateral limb during stance and (2) the difference in knee flexion angle at initial foot contact between the meniscectomized and contralateral limbs.

STUDY DESIGN

Controlled laboratory study.

METHODS

This study compared side-to-side differences in knee flexion and rotation angles during static and dynamic activities. Thirteen patients (2 female) were tested in a motion capture laboratory at 6 ± 2 months after unilateral, arthroscopic, partial medial meniscectomy during a static reference pose and during 3 dynamic activities: walking, stair ascent, and stair descent.

RESULTS

The meniscectomized limb demonstrated more external tibial rotation compared with the contralateral limb during dynamic activities, and there was a trend that this offset increased with activity demand (repeated-measures analysis of variance [ANOVA] for activity, P = .07; mean limb difference: static pose, -0.1° ± 3.3°, P = .5; walking, 1.2° ± 3.8°, P = .1; stair ascent, 2.0° ± 3.2°, P = .02; stair descent, 3.0° ± 3.5°, P = .005). Similarly, the meniscectomized knee was more flexed at initial contact than the contralateral limb during dynamic activities (repeated-measures ANOVA for activity P = .006; mean limb difference: reference pose, 1.0° ± 2.5°, P = .09; walking, 2.0° ± 3.9°, P = .05; stair ascent, 5.9° ± 5.3°, P = .009; stair descent, 3.5° ± 4.0°, P = .004).

CONCLUSION

These results suggest both a structural element and a potential muscular element for the differences in kinematics after partial medial meniscectomy and highlight the importance of challenging the knee with activities of increased demands to detect differences in kinematics from the contralateral limb.

CLINICAL RELEVANCE

With further investigation, these findings could help guide clinical rehabilitation of patients with torn meniscus tissue, especially in the context of the patients' increased risk of joint degeneration.