Arthroscopic surgery for degenerative tears of the meniscus: a systematic review and meta-analysis

Background:

Arthroscopic surgery for degenerative meniscal tears is a commonly performed procedure, yet the role of conservative treatment for these patients is unclear. This systematic review and meta-analysis evaluates the efficacy of arthroscopic meniscal débridement in patients with knee pain in the setting of mild or no concurrent osteoarthritis of the knee in comparison with nonoperative or sham treatments.

Methods:

We searched MEDLINE, Embase and the Cochrane databases for randomized controlled trials (RCTs) published from 1946 to Jan. 20, 2014. Two reviewers independently screened all titles and abstracts for eligibility. We assessed risk of bias for all included studies and pooled outcomes using a random-effects model. Outcomes (i.e., function and pain relief) were dichotomized to short-term (< 6 mo) and long-term (< 2 yr) data.

Results:

Seven RCTs (n = 805 patients) were included in this review. The pooled treatment effect of arthroscopic surgery did not show a significant or minimally important difference (MID) between treatment arms for long-term functional outcomes (standardized mean difference [SMD] 0.07, 95% confidence interval [CI] −0.10 to 0.23). Short-term functional outcomes between groups were significant but did not exceed the threshold for MID (SMD 0.25, 95% CI 0.02 to 0.48). Arthroscopic surgery did not result in a significant improvement in pain scores in the short term (mean difference [MD] 0.20, 95% CI −0.67 to 0.26) or in the long term (MD −0.06, 95% CI −0.28 to 0.15). Statistical heterogeneity was low to moderate for the outcomes.

Interpretation:

There is moderate evidence to suggest that there is no benefit to arthroscopic meniscal débridement for degenerative meniscal tears in comparison with nonoperative or sham treatments in middle-aged patients with mild or no concomitant osteoarthritis. A trial of nonoperative management should be the first-line treatment for such patients.Arthroscopic meniscal débridement is one of the most commonly performed procedures in orthopedic surgery. More than 700 000 such procedures are performed each year in the United States, and more than 4 million are performed each year worldwide, with substantial economic and social burdens.^1–6 Many patients who undergo arthroscopic meniscal débridement have concurrent osteoarthritis, and orthopedic surgeons are often challenged to determine the true cause of patients’ symptoms: the meniscal tear, osteoarthritis or a combination of both.⁷Although 2 well-designed randomized controlled trials (RCTs)^8,9 have shown a lack of efficacy for arthroscopic surgery in patients with severe and advanced knee arthritis, many patients present with degenerative meniscal tears and mild or minimal concurrent osteoarthritis.¹⁰ Patients with degenerative meniscal tears in the setting of mild osteoarthritis may experience functional improvement or pain relief with arthroscopic surgery,^11–14 but the role of conservative treatment is unclear.^15–17 Arthroscopic surgery involves the potential for complications, which must be weighed against the prognosis for relief from presenting symptoms.^6,18The objective of this systematic review and meta-analysis was to evaluate the efficacy of arthroscopic meniscal débridement in comparison with nonoperative or sham treatments in patients with degenerative meniscal tears and knee pain with regard to function and pain relief in the short term (< 6 mo) and long term (< 2 yr).     

The effect of meniscal tears and resultant partial meniscectomies on the knee contact stresses: a finite element analysis

Knee osteoarthritis (OA) is believed to result from high levels of contact stresses on the articular cartilage and meniscus after meniscal damage. This study investigated the effect of meniscal tears and partial meniscectomies on the peak compressive and shear stresses in the human knee joint. An elaborate three-dimensional finite element model of knee joint including bones, articular cartilages, menisci and main ligaments was developed from computed tomography and magnetic resonance imaging images. This model was used to model four types of meniscal tears and their resultant partial meniscectomies and analysed under an axial 1150 N load at 0° flexion. Three different conditions were compared: a healthy knee joint, a knee joint with medial meniscal tears and a knee joint following partial meniscectomies. The numerical results showed that each meniscal tear and its resultant partial meniscectomy led to an increase in the peak compressive and shear stresses on the articular cartilages and meniscus in the medial knee compartment, especially for partial meniscectomy. Among the four types of meniscal tears, the oblique tear resulted in the highest values of the peak compressive and shear stresses. For the four partial meniscectomies, longitudinal meniscectomy led to the largest increase in these two stresses. The lateral compartment was minimally affected by all the simulations. The results of this study demonstrate meniscal tear and its resultant partial meniscectomy has a positive impact on the maintenance of high levels of contact stresses, which may improve the progression of knee OA, especially for partial meniscectomy. Surgeons should adopt a prudent strategy to preserve the greatest amount of meniscus possible.     

High articular levels of the angiogenetic factors VEGF and VEGF-receptor 2 as tissue healing biomarkers after single bundle anterior cruciate ligament reconstruction

Various factors may account for the positive association between meniscal repair and anterior cruciate ligament reconstruction, one being the modulation of healing response of meniscal fibrochondrocytes by growth factors released with intra-articular bleeding and fibrin clot formation. Analysis of vascular endothelial growth factor (VEGF) and its receptors, VEGFR1 and VEGFR2, may be useful in the clinical assessment of bone and soft-tissue remodeling. We measured systemic and local levels of VEGF (VEGF165), VEGFR1 and VEGFR2 after either arthroscopic partial meniscectomy (APM) or single-bundle anterior cruciate ligament reconstruction (ACLR) in order to determine the local effect of bone tunnelling and notchplasty on the release of these growth factors. The study population included 40 patients: 20 consecutive patients had undergone ACLR with hamstring grafts and 20 had undergone APM. Thirty minutes after the end of the operation, knee joint fluid samples were collected via the drainage tube and at the same time venous blood samples were drawn. In both sets of samples, VEGF, VEGFR1 and VEGFR2 concentrations were determined by enzyme-linked immunosorbent assay (ELISA). No significant differences in VEGF, VEGFR1 or VEGFR2 concentrations in the venous blood were observed between the two treatment groups. In contrast, VEGF and VEGFR2 levels were significantly higher in the knee joint fluid of the ACLR group; furthermore, VEGF and VEGFR1 were significantly higher in the knee joint fluid than in the venous blood, whereas VEGFR2 was lower in the knee joint fluid than in the venous blood. Local release of VEGF and its angiogenetic receptor VEGFR2, but not the negative regulator VEGFR1, was significantly higher after ACLR than after APM, indicating a better vasculogenic potential for enhanced bone-graft and meniscus healing. These results could suggest that VEGF and VEGFRs could be considered as good biomarkers of tissue healing after knee joint surgery.     

Factors predicting knee function in patients with meniscal lesions

The relationships between the magnitude of strength and muscle activation (EMG activity) deficits during maximal isokinetic knee movements and clinical and anthropometric factors (pain, effusion, type of meniscal lesion, degenerative changes, duration of symptoms and age) were studied in a group of 34 patients 5 days (5.3 ± 6.2 days) before arthroscopic meniscectomy. Moderate correlations were found between deficits in the area under the torque-angle curve (work) and the activation level in the agonist muscles during both the extension and flexion tests at 30° s⁻¹ and 180° s⁻¹ suggesting that the decrease in the isokinetic mechanical output is dependent on the reduced muscle activation. The severity of pain during tests was the best predictive clinical factor for the size of the work and EMG deficits but each of the tollowing factors: the presence of knee effusion and thigh atrophy, the type of meniscal lesion and the age of the patients, also had some predictive value for the magnitude of the deficits. In contrast, the duration of symptoms and the presence of osteo-articular degenerative changes were not related to the preoperative isokinetic knee performance. These results suggest that older patients (especially over 45 yr) with bucket-handle meniscal tears, knee effusion, thigh atrophy and severe pain on exertion, are most likely to have poor preoperative knee isokinetic performance. Since the magnitude of the pre- and postoperative knee deficits are correlated, it is important to identify patients at risk preoperatively so that optimal rehabilitation can be instituted.     

Comparison of Medial and Lateral Meniscus Root Tears

The meniscus root plays an essential role in maintaining the circumferential hoop tension and preventing meniscal displacement. Studies on meniscus root tears have investigated the relationship of osteoarthritis and an anterior cruciate ligament tear. However, few studies have directly compared the medial and lateral root tears. To assess the prevalence of meniscal extrusion and its relationship with clinical features in medial and lateral meniscus root tears, we performed a retrospective review of the magnetic resonance imaging (MRI) results of 42 knee patients who had meniscus posterior horn root tears and who had undergone arthroscopic operations. The presence of meniscal extrusion was evaluated and the exact extent was measured from the tibial margin. The results were correlated with arthroscopic findings. Clinical features including patients’ ages, joint abnormalities, and previous trauma histories were evaluated. Twenty-two patients had medial meniscus root tears (MMRTs) and twenty patients had lateral meniscus root tears (LMRTs). Meniscal extrusion was present in 18 MMRT patients and one LMRT patient. The mean extent of extrusion was 4.2mm (range, 0.6 to 7.8) in the MMRT group and 0.9mm (range, -1.9 to 3.4) in the LMRT group. Five patients with MMRT had a history of trauma, while 19 patients with LMRT had a history of trauma. Three patients with MMRT had anterior cruciate ligament (ACL) tears, while 19 patients with LMRT had ACL tears. The mean age of the patients was 52 years (range: 29–71 years) and 30 years (range: 14–62 years) in the MMRT and LMRT group, respectively. There was a significant correlation between a MMRT and meniscal extrusion (p<0.0001), and between an ACL tear and LMRT (p<0.0001). A history of trauma was significantly common in LMRT (p<0.0001). LMRT patients were significantly younger than MMRT patients (p<0.0001). Kellgren-Lawrence (K-L) grade differed significantly between MMRT and LMRT group (p<0.0001). Meniscal extrusion is common in patients with MMRTs. However, it is rare in patients with LMRTs, which are more commonly associated with a history of trauma and ACL tears.     

Defining the Value of Future Research to Identify the Preferred Treatment of Meniscal Tear in the Presence of Knee Osteoarthritis

Background

Arthroscopic partial meniscectomy (APM) is extensively used to relieve pain in patients with symptomatic meniscal tear (MT) and knee osteoarthritis (OA). Recent studies have failed to show the superiority of APM compared to other treatments. We aim to examine whether existing evidence is sufficient to reject use of APM as a cost-effective treatment for MT+OA.

Methods

We built a patient-level microsimulation using Monte Carlo methods and evaluated three strategies: Physical therapy (‘PT’) alone; PT followed by APM if subjects continued to experience pain (‘Delayed APM’); and ‘Immediate APM’. Our subject population was US adults with symptomatic MT and knee OA over a 10 year time horizon. We assessed treatment outcomes using societal costs, quality-adjusted life years (QALYs), and calculated incremental cost-effectiveness ratios (ICERs), incorporating productivity costs as a sensitivity analysis. We also conducted a value-of-information analysis using probabilistic sensitivity analyses.

Results

Calculated ICERs were estimated to be $12,900/QALY for Delayed APM as compared to PT and $103,200/QALY for Immediate APM as compared to Delayed APM. In sensitivity analyses, inclusion of time costs made Delayed APM cost-saving as compared to PT. Improving efficacy of Delayed APM led to higher incremental costs and lower incremental effectiveness of Immediate APM in comparison to Delayed APM. Probabilistic sensitivity analyses indicated that PT had 3.0% probability of being cost-effective at a willingness-to-pay (WTP) threshold of $50,000/QALY. Delayed APM was cost effective 57.7% of the time at WTP = $50,000/QALY and 50.2% at WTP = $100,000/QALY. The probability of Immediate APM being cost-effective did not exceed 50% unless WTP exceeded $103,000/QALY.

Conclusions

We conclude that current cost-effectiveness evidence does not support unqualified rejection of either Immediate or Delayed APM for the treatment of MT+OA. The amount to which society would be willing to pay for additional information on treatment outcomes greatly exceeds the cost of conducting another randomized controlled trial on APM.     

Calcium deposition in osteoarthritic meniscus and meniscal cell culture

Introduction  

Calcium crystals exist in the knee joint fluid of up to 65% of osteoarthritis (OA) patients and the presence of these calcium crystals correlates with the radiographic evidence of hyaline cartilaginous degeneration. This study sought to examine calcium deposition in OA meniscus and to investigate OA meniscal cell-mediated calcium deposition. The hypothesis was that OA meniscal cells may play a role in pathological meniscal calcification.     

3D finite element model of meniscectomy: changes in joint contact behavior

The goal of this study is to quantify changes in knee joint contact behavior following varying degrees of the medial partial meniscectomy. A previously validated 3D finite element model was used to simulate 11 different meniscectomies. The accompanying changes in the contact pressure on the superior surface of the menisci and tibial plateau were quantified as was the axial strain in the menisci and articular cartilage. The percentage of medial meniscus removed was linearly correlated with maximum contact pressure, mean contact pressure, and contact area. The lateral hemi-joint was minimally affected by the simulated medial meniscectomies. The location of maximum strain and location of maximum contact pressure did not change with varying degrees of partial medial meniscectomy. When 60% of the medial meniscus was removed, contact pressures increased 65% on the remaining medial meniscus and 55% on the medial tibial plateau. These data will be helpful for assessing potential complications with the surgical treatment of meniscal tears. Additionally, these data provide insight into the role of mechanical loading in the etiology of post-meniscectomy osteoarthritis.     

Integrative repair of the meniscus: lessons from in vitro studies

Current therapies for meniscal injury seek to preserve and repair damaged tissue since loss of meniscal tissue is associated with degenerative changes in the joint, ultimately leading to osteoarthritis (OA). After a meniscal tear, the difficulty of integrating juxtaposed meniscal surfaces continues to be an obstacle. In order to determine the local factors that are necessary for successful tissue repair, previous studies have developed in vitro model systems that allow both biological and quantitative biomechanical measures of meniscus repair. Many studies have shown the importance of individual factors in meniscus metabolism, but there is a complex interplay among a variety of factors that influence meniscal healing, including inflammatory cytokines, growth factors, mechanical loading, and zonal differences in cell and tissue properties. In particular, the upregulation of inflammatory cytokines following joint injury appears to have significant catabolic influences on meniscal cell metabolic activity that must be overcome in order to promote repair. In the presence of inflammatory cytokines, such as interleukin-1 (IL-1) or tumor necrosis factor alpha (TNF-alpha), intrinsic meniscal repair in vitro is significantly inhibited. While anabolic growth factors, such as transforming growth factor-beta1 (TGF-beta1), enhance meniscal repair, they cannot completely overcome the IL-1-mediated inhibition of repair. The mechanisms by which these mediators influence meniscal repair, and their interactions with other factors in the microenvironment, such as mechanical loading, remain to be determined. Future studies must address these complex interactions during meniscal healing to ultimately enhance meniscal repair.     

Effects of the type of meniscal lesion on knee function

The relationship between the type of meniscal lesion (bucket-handle, flap or degenerative tears) and preoperative knee function (5.1±6.2 days before arthroscopic meniscectomy) was studied in 35 patients. Patients with bucket-handle tears (group B, n=12) had large knee extension work deficits during maximal voluntary contractions at 30° and 180°/s (Kin-Com dynamometer). These work deficits were accompanied by proportional decreases in the prime mover or agonist-EMG levels (VM: vastus medialis and/or VL: vastus lateralis). These patients had smaller deficits during flexion movements at 30°/s. Moreover, a larger number of negative clinical signs and symptoms (pain at rest and during tests, locking, thigh atrophy, extension and flexion movement deficits larger than 10°) were found with an equal or a higher prevalence in group B than in the other groups. Patients with flap tears (group F, n=15) had deficits in work and agonist-EMG activity (VM and VL) only during the extension tests. In contrast, patients with degenerative tears (group D, n=8) had a work deficit and a concomitant decrease in the EMG level of the medial gastrocnemius (MG), only during the flexion test at 30°/s. Comparable mean knee function scores, as measured by the Lysholm and Gillquist questionnaire [35], were obtained for the three groups of patients, suggesting that this measure was not sensitive enough to discern functional differences related to types of meniscal tears. The results of this study have demonstrated a link between the type of meniscal lesion and the consequent preoperative knee joint disability profile as defined by comparison with the sound leg. These results emphasize the need to consider meniscal lesion type and an individual's preoperative strength deficit when group comparisons of patients are made or the effects of therapy (arthroscopic surgery and rehabilitation) are evaluated.     

A longitudinal study of impact and early stance loads during gait following arthroscopic partial meniscectomy

People following arthroscopic partial medial meniscectomy (APM) are at increased risk of developing knee osteoarthritis. High impact loading and peak loading early in the stance phase of gait may play a role in the pathogenesis of knee osteoarthritis. This was a secondary analysis of longitudinal data to investigate loading-related indices at baseline in an APM group (3 months post-surgery) and a healthy control group, and again 2 years later (follow-up). At baseline, 82 participants with medial APM and 38 healthy controls were assessed, with 66 and 23 re-assessed at follow-up, respectively. Outcome measures included: (i) heel strike transient (HST) presence and magnitude, (ii) maximum loading rate, (iii) peak vertical force (F_z) during early stance. At baseline, maximum loading rate was lower in the operated leg (APM) and non-operated leg (non-APM leg) compared to controls (p≤0.03) and peak F_z was lower in the APM leg compared to non-APM leg (p≤0.01). Over 2 years, peak F_z increased in the APM leg compared to the non-APM leg and controls (p≤0.01). Following recent APM, people may adapt their gait to protect the operated knee from excessive loads, as evidenced by a lower maximum loading rate in the APM leg compared to controls, and a reduced peak F_z in the APM leg compared to the non-APM leg. No differences at follow-up may suggest an eventual return to more typical gait. However, the increase in peak F_z in the APM leg may be of concern for long-term joint health given the compromised function of the meniscus.     

Mesenchymal stem cells for enhancing biological healing after meniscal injuries

The meniscus is a semilunar fibrocartilage structure that plays important roles in maintaining normal knee biomechanics and function. The roles of the meniscus, including load distribution, force transmission, shock absorption, joint stability, lubrication, and proprioception, have been well established. Injury to the meniscus can disrupt overall joint stability and cause various symptoms including pain, swelling, giving-way, and locking. Unless treated properly, it can lead to early degeneration of the knee joint. Because meniscal injuries remain a significant challenge due to its low intrinsic healing potential, most notably in avascular and aneural inner two-thirds of the area, more efficient repair methods are needed. Mesenchymal stem cells (MSCs) have been investigated for their therapeutic potential in vitro and in vivo. Thus far, the application of MSCs, including bone marrow-derived, synovium-derived, and adipose-derived MSCs, has shown promising results in preclinical studies in different animal models. These preclinical studies could be categorized into intra-articular injection and tissue-engineered construct application according to delivery method. Despite promising results in preclinical studies, there is still a lack of clinical evidence. This review describes the basic knowledge, current treatment, and recent studies regarding the application of MSCs in treating meniscal injuries. Future directions for MSC-based approaches to enhance meniscal healing are suggested.     

Association between meniscal tears and the peak external knee adduction moment and foot rotation during level walking in postmenopausal women without knee osteoarthritis: a cross-sectional study

Introduction  

Meniscal injury is a risk factor for the development and progression of knee osteoarthritis, yet little is known about risk factors for meniscal pathology. Joint loading mediated via gait parameters may be associated with meniscal tears, and determining whether such an association exists was the aim of this study.     

The effect of kinematic and kinetic changes on meniscal strains during gait

The menisci play an important role in load distribution, load bearing, joint stability, lubrication, and proprioception. Partial meniscectomy has been shown to result in changes in the kinematics and kinetics at the knee during gait that can lead to progressive meniscal degeneration. This study examined changes in the strains within the menisci associated with kinematic and kinetic changes during the gait cycle. The gait changes considered were a 5 deg shift toward external rotation of the tibia with respect to the femur and an increased medial-lateral load ratio representing an increased adduction moment. A finite element model of the knee was developed and tested using a cadaveric specimen. The cadaver was placed in positions representing heel-strike and midstance of the normal gait, and magnetic resonance images were taken. Comparisons of the model predictions to boundaries digitized from images acquired in the loaded states were within the errors produced by a 1 pixel shift of either meniscus. The finite element model predicted that an increased adduction moment caused increased strains of both the anterior and posterior horns of the medial meniscus. The lateral meniscus exhibited much lower strains and had minimal changes under the various loading conditions. The external tibial rotational change resulted in a 20% decrease in the strains in the posterior medial horn and increased strains in the anterior medial horn. The results of this study suggest that the shift toward external tibial rotation seen clinically after partial medial meniscectomy is not likely to cause subsequent degenerative medial meniscal damage, but the consequence of this kinematic shift on the pathogenesis of osteoarthritis following meniscectomy requires further consideration.     

Structured three-dimensional co-culture of mesenchymal stem cells with meniscus cells promotes meniscal phenotype without hypertrophy

Menisci play a crucial role in weight distribution, load bearing, shock absorption, lubrication, and nutrition of articular cartilage within the knee joint. Damage to the meniscus typically does not heal spontaneously due to its partial avascular nature. Partial or complete meniscectomy is a common clinical treatment of the defective meniscus. However, this procedure ultimately leads to osteoarthritis due to increased mechanical stress to the articular cartilage. Meniscus tissue engineering offers a promising solution for partial or complete meniscus deficiency. Mesenchymal stem cells (MSC) have the potential to differentiate into meniscal fibrochondrocyte as well as deliver trophic effects to the differentiated cells. This study tested the feasibility of using MSC co-cultured with mature meniscal cells (MC) for meniscus tissue engineering. Structured cell pellets were created using MC and MSC at varying ratios (100:0, 75:25, 50:50, 25:75, and 0:100) and cultured with or without transforming growth factor-beta 3 supplemented chondrogenic media for 21 days. The meniscal and hypertrophic gene expression, gross appearance and structure of the pellets, meniscus extracellular matrix (ECM), histology and immunohistochemistry of proteoglycan and collagen were evaluated. Co-culture of MC with MSC at 75:25 demonstrated highest levels of collagen type I and glycosaminoglycans (GAG) production, as well as the lowest levels of hypertrophic genes, such as COL10A1 and MMP13. All co-culture conditions showed better meniscus ECM production and hypertrophic inhibition as compared to MSC culture alone. The collagen fiber bundles observed in the co-cultures are important to produce heterogenic ECM structure of meniscus. In conclusion, co-culturing MC and MSC is a feasible and efficient approach to engineer meniscus tissue with enhanced ECM production without hypertrophy.     

关节镜治疗膝关节盘状半月板损伤的疗效及术后疼痛的影响因素研究

目的:探讨关节镜治疗膝关节盘状半月板损伤的疗效以及患者术后疼痛的原因、影响因素。方法:选取2011年7月至2013年7月我院收治的46例膝关节盘状半月板损伤的患者作为研究对象,运用统计学方法分析关节镜的手术疗效。结果:根据Lkeuchi评分标准进行评分:优29例(63.04%),良12例(26.09%),中3例(6.52%),差2例(4.35%),优良率为89.13%。两组患者性别、BMI(体质指数)之间无差异,但是疼痛与年龄、负重早晚、关节软骨损伤、术后是否冷敷均有关系,且差异具有统计学意义(P0.05)。结论:关节镜治疗膝关节盘状半月板损伤具有确切的疗效,术后疼痛与多种因素有关。     

关节镜治疗膝关节盘状半月板损伤的疗效及术后疼痛的影响因素研究

目的：探讨关节镜治疗膝关节盘状半月板损伤的疗效以及患者术后疼痛的原因、影响因素。方法：选取2011年7月至2013年7月我院收治的46例膝关节盘状半月板损伤的患者作为研究对象,运用统计学方法分析关节镜的手术疗效。结果：根据Lkeuchi评分标准进行评分：优29例（63．04％）,良12例（26．09％）,中3例（6．52％）,差2例（4．35％）,优良率为89．13％。两组患者性别、BMI（体质指数）之间无差异,但是疼痛与年龄、负重早晚、关节软骨损伤、术后是否冷敷均有关系,且差异具有统计学意义（P〈0．05）。结论：关节镜治疗膝关节盘状半月板损伤具有确切的疗效,术后疼痛与多种因素有关。     

An overview of the different approaches used in the development of meniscal tissue engineering

The menisci are important fibrocartilaginous structures which give lubrication, shock absorption, nutrition and stabilisation to the knee joint, and also help transfer load. The meniscus' extracellular matrix possesses a complex architecture which is not uniform throughout the tissue. The inner third of the meniscus is composed of hyaline cartilage and the outer meniscus is composed of fibrocartilage. In a mature meniscus only the outer 10-25% is vascularised. There are various types of pathology associated with the meniscus. Previously, surgical techniques used to be considered as conventional treatment for meniscal lesions. However lesions in the avascular regions of the meniscus would rarely heal appropriately. It has been found that total menisectomies in patients may increase their chance of suffering from osteoarthritis in the future. Meniscal tissue engineering has been developed in an attempt to help improve the healing potential of avascular meniscal regions. Many different concepts and approaches have been tried and tested, such as the application of natural and synthetic scaffolds, mesenchymal stem cells, growth factors, fibrin glue and more. The objective of this review is to summarise the different approaches that have been used in the development of meniscal tissue engineering. The focus of this review is to evaluate the strengths and weaknesses of the studies that have been carried out, and from there determine what we have learnt from them in order to further the development in meniscal tissue engineering.     

Sex Difference in Contusion of the Medial Femoral Condyle Rim-Association with MRI Occult Meniscal Tears in the ACL Deficient Knee

BackgroundMeniscal tears, specifically lateral meniscal tears, have a larger than expected un-derdiagnosis rate in the presence of an ACL tear. The purpose of our study was to search for an MRI bone contusion pattern associated with MRI occult meniscal tears in patients with an ACL tear, specifically a contusion of the rim of the medial femoral condyle (RMFC). Our hypothesis was that there would be a significant association between RMFC contusions and MRI occult meniscal tears in patients with an ACL tear. We also searched for a difference between sexes with respect to the presence of the RMFC contusion in the setting of an occult meniscal tear. We also categorized the type, size, and location of these occult meniscal tears in the setting of an ACL tear.Methods This was a retrospective study that examined characteristics of occult meniscal tears and their association with a RMFC bone contusion. IRB approval was obtained. The date range of the study was June 2009 through December 2015. 6392 consecutive knee MRI reports in patients with an ACL deficient knee were reviewed. The study group included 22 patients with MRI occult meniscal tears, the control group included 110 patients. Relevant statistical values were calculated.ResultsThe most common type of occult meniscal tears were small radial and small longitudinal tears of the lateral meniscus. Occult meniscal tears were associated with an RMFC contusion in the study group (p=0.0457), particularly in males (p = 0.0003). In males with a torn ACL, the sensitivity of an RMFC contusion for an occult meniscal tear was 80%.ConclusionIn males with an ACL tear, there was a significant association between a contusion of the RMFC and an occult meniscal tear (commonly small radial or small peripheral partial-thickness longitudinal tears). RMFC contusions were reliably identified by radiologists in this study.Level of Evidence: II     

Quantification of meniscal volume by segmentation of 3T magnetic resonance images

Meniscal injuries place the knee at risk for early osteoarthritis (OA) because they disrupt their load-bearing capabilities. Partial resection is routinely performed to alleviate symptomatic meniscal tears. While the removal of meniscal tissue may not be the only factor associated with partial meniscectomy outcome, the amount removed certainly contributes to functional loss. It is unknown, however, whether there is a critical amount of meniscal tissue that can be removed without diminishing the structure's chondroprotective role. In order to examine the existence of such a threshold, it is necessary to accurately quantify meniscal volume both before and after partial meniscectomy to determine the amount of meniscal tissue removed. Therefore, our goal was to develop and validate an MR-based method for assessing meniscal volume. The specific aims were: (1) to evaluate the feasibility of the MR-based segmentation method; (2) to determine the method's reliability for repeated measurements; and (3) to validate its accuracy in situ. MR images were obtained on a 3T magnet, and each scan was segmented using a biplanar approach. The MR-based volumes for each specimen were compared to those measured by water displacement. The results indicate that the biplanar approach of measuring meniscal volumes is accurate and reliable. The calculated volumes of the menisci were within 5% of the true values, the coefficients of variation were 4%, and the intraclass correlation coefficients were greater than 0.96. These data demonstrate that this method could be used to measure the amount of meniscal tissue excised during partial meniscectomy to within 125.7 mm(3).