Meniscal repair devices: a clinical and biomechanical literature review

Meniscal Tear Management Associated with ACL Reconstruction

Meniscal lesions often occur in association with anterior cruciate ligament (ACL) tears at the moment of the injury or, secondarily, as a consequence of knee instability. Both ACL and meniscus lesions are associated with a higher risk of osteoarthritis. Adequate treatment of these lesions reduces the rate of degenerative changes in the affected knee. Meniscal tears should be addressed concomitantly with ACL reconstruction and the treatment must be oriented towards preserving the meniscal tissue anytime this is possible. Several options for approaching a meniscus tear are available. The meniscal suture should always be considered, and, if possible, meniscectomy should be the last choice. “Masterly neglect” is a valuable option in selected cases.

Bucket handle meniscus tears in low-resource settings can be successfully treated with a cost-effective technique

PURPOSE

In regions of the world where resources can limit medical care (limited-resource settings, LRS), most meniscal tears are often treated with meniscectomy. A simple, low-cost option for meniscal repair has been developed. We sought to evaluate patient reported outcomes (PROMs) and clinical failure rates of bucket handle meniscus tears (BHTs) treated with meniscal repair in a LRS.

METHODS

We prospectively enrolled patients over 18 who were treated for BHT with meniscal repair in a LRS. Meniscal repair was primarily accomplished using an outside-in technique. Pre-injury and final follow-up PROMs were recorded. Clinical failure was defined as the need for re-operation or symptoms that prevented the patient from returning to recreational activities or work responsibilities.

RESULTS

Nineteen patients with a mean age of 25.4 years were eligible. Two patients sustained a clinical failure (10.5%). At mean follow-up of 40.6 months, there was significant improvement in all PROMs from baseline. Subgroup analysis revealed no significant difference in the failure group compared to the success group in number of knots used, pre-injury Tegner score, number of devices used, suture type, or technique.

CONCLUSION

Bucket-handle meniscal tears can be repaired using a low-cost technique resulting in satisfactory healing rates and excellent outcomes.

Prospects of Using Biocatalysis for the Synthesis and Modification of Polymers

Trends in the dynamically developing application of biocatalysis for the synthesis and modification of polymers over the past 5 years are considered, with an emphasis on the production of biodegradable, biocompatible and functional polymeric materials oriented to medical applications. The possibilities of using enzymes not only as catalysts for polymerization but also for the preparation of monomers for polymerization or oligomers for block copolymerization are considered. Special attention is paid to the prospects and existing limitations of biocatalytic production of new synthetic biopolymers based on natural compounds and monomers from biomass, which can lead to a huge variety of functional biomaterials. The existing experience and perspectives for the integration of bio- and chemocatalysis in this area are discussed.

Biomechanical comparison of four tibial fixation techniques for meniscal root sutures in posterior medial meniscus root repair: A porcine study

OBJECTIVE

This study hypothesized that the suture anchor of tibial fixation method of PMMR repair technique is the main factor which reduce the gap formation or over displacement of tear site in initial healing, and then investigated the fixation stability of 4 different tibial fixations through cyclic and ultimate failure load testing of meniscal root sutures.

METHODS

Twenty-four porcine tibiae with intact medial meniscus roots were randomly assigned into 4 groups: transosseous suture, washer, suture anchor, or screw with washer. Each sample underwent cyclic loading followed by a load-to-failure test. Displacement, maximum load to failure, stiffness, and elongation at failure load were recorded.

RESULTS

The maximum average load and displacement at failure for each of the repair groups were as follows: transosseous suture, 232.8 N and 12.16 mm; washer, 189.9 N and 21.5 mm; suture anchor, 140.6 N and 13.8 mm; and screw with washer, 167.9 N and 18.9 mm. The maximum stiffness values for each of the repair groups were as follows: transosseous suture, 19.5 ± 0.7 N/mm; washer, 21.5 ± 1.4 N/mm; suture anchor, 13.8 ± 0.7 N/mm; and screw with washer, 18.9 ± 3.9 N/mm. The mean elongation across the repairs for each of the repair groups after 1000 loading cycles was: transosseous suture, 3.74 ± 0.28 mm; washer, 3.04 ± 0.13 mm; suture anchor, 2.25 ± 0.33 mm; and screw with washer, 2.43 ± 0.19 mm. The mean elongation was significantly less with the suture anchor than with the other techniques (p < .05).

CONCLUSION

Under physiological loading, our results indicate that a slower rehabilitation program with limited flexion and only partial weight bearing is advised when using a suture anchor because of the lower maximum load and stiffness.

THE TRANSLATIONAL POTENTIAL OF THIS ARTICLE

Tibial fixation using a washer or a screw with a washer is an effective and cost-saving technique when an option is required with high stiffness and low displacement at failure.

Second-look arthroscopic findings and clinical outcomes of meniscal repair with concomitant anterior cruciate ligament reconstruction: comparison of suture and meniscus fixation device

INTRODUCTION

The purpose of this study was to evaluate the healing rate of repaired meniscus and functional outcomes of patients who received all-inside meniscal repair using sutures or devices with concomitant arthroscopic anterior cruciate ligament (ACL) reconstruction.

MATERIALS AND METHODS

Among the patients who have ACL tear and posterior horn tear of medial or lateral meniscus, 61 knees who received all-inside repair using sutures (suture group, n = 28) or meniscal fixation devices (device group, n = 33) with concomitant ACL reconstruction during the period from January 2012 to December 2015, followed by second-look arthroscopy, were retrospectively reviewed. Healing status of the repair site was assessed by second-look arthroscopy. Through the clinical assessment, clinical success (negative medial joint line tenderness, no history of locking or recurrent effusion, and negative McMurray test) rate of the repaired meniscus and functional outcomes (International Knee Documentation Committee subjective score and Lysholm knee score) was evaluated.

RESULTS

In a comparison of healing status of repaired meniscus evaluated by second-look arthroscopy, suture group had 23 cases of complete healing (82.1%), 4 cases of incomplete healing (14.3%), and 1 case of failure (3.6%). Device group had 18 cases of complete healing (54.5%), 4 cases of incomplete healing (24.2%), and 7 cases of failure (21.2%) (p = 0.048). Clinical success rate of the meniscal repair was 89.3% (25 cases) and 81.8% (27 cases) in suture group and device group, respectively (p = 0.488). No significant difference of functional outcomes was observed between the two groups (p > 0.05, both parameters).

CONCLUSIONS

Among the patients who received meniscal repair with concomitant ACL reconstruction, suture group showed better healing status of repaired meniscus based on the second-look arthroscopy than device group. However, no significant between-group difference of clinical success rate and functional outcomes was observed.

A Systematic Review and Meta-Analysis of Arthroscopic Meniscus Repair in Young Patients: Comparison of All-Inside and Inside-Out Suture Techniques

Purpose

The purposes of the present study were to review published studies that investigated arthroscopic meniscus repair to treat meniscus injury in young patients and to compare all-inside and inside-out suture techniques.

Methods

Various electronic databases were queried for published articles, and this search was updated in August 2017 for evaluating the outcomes of arthroscopic meniscus surgery in young patients. Data search, extraction, analysis, and quality assessment were performed according to the Cochrane Collaboration guidelines, and the clinical outcomes were evaluated using various outcome values in young patients according to suture techniques.

Results

Three randomized controlled trials and three prospective comparative studies were included in this systematic review and meta-analysis. There were no significant differences in clinical outcomes such as meniscus healing rate (risk ratio [RR], 1.11; 95% confidence interval [CI], 0.90 to 1.37; I²=39%) and perioperative complications (RR, 0.62; 95% CI, 0.23 to 1.72; I²=43%) between all-inside and inside-out techniques for meniscus repair.

Conclusions

The present study shows favorable results for clinical outcomes such as meniscus healing rate and perioperative complications in young patients. Furthermore, based on our results, both all-inside and inside-out meniscal suture techniques are equally effective in these patients.

Factors Affecting the Outcomes of Arthroscopically Repaired Traumatic Vertical Longitudinal Medial Meniscal Tears

BACKGROUND

Although numerous studies have assessed arthroscopic medial meniscal repairs, few studies have focused on factors affecting outcomes of vertical longitudinal and bucket-handle repairs.

PURPOSE

To evaluate the factors affecting clinical outcomes of arthroscopically repaired traumatic vertical longitudinal and bucket-handle medial meniscal tears.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

A total of 223 patients underwent arthroscopic repair for medial meniscal tears between 2007 and 2012; 140 patients had isolated tears or concurrent anterior cruciate ligament (ACL) reconstruction, and 80 patients (76 men, 4 women; mean age, 29.1 years; range, 18-49 years) had vertical longitudinal tears and were included in the study. Pre- and postoperative functional status was assessed using physical examinations with Lysholm and International Knee Documentation Committee (IKDC) scores. Barrett criteria were used for clinical assessment of meniscal healing, and magnetic resonance imaging (MRI) was used as the radiologic assessment method. The effects of tear location, length, chronicity, and type; suturing technique; concurrent ACL reconstruction; and patient age, sex, and smoking habits were also investigated.

RESULTS

The mean follow-up period was 51.2 ± 9.4 months (range, 34-85 months). The mean Lysholm and IKDC scores improved at final follow-up (both Ps <.001). According to clinical scores, Barrett criteria, and MRI, failure was noted in 12 patients (15%). There were no significant differences in age, tear length, tear type, concurrent ACL rupture, suturing technique, or location of the meniscal repair between the success and failure groups. Failure rates were higher for red-white zone tears than for red-red zone tears (10/30, 33.3% vs 2/50, 4%; P = .004). Tear chronicity significantly affected failure rates. Early repairs had higher healing rates than late repairs (100% vs 73.4%; P = .008). Failure rates were higher for smokers than for nonsmokers (9/24, 37.5% vs 3/56, 5.3%; P = .008).

CONCLUSION

Peripheral tears and early repairs have better outcomes and patient satisfaction. Smoking adversely affects meniscal healing.

A study to identify and characterize the stem/progenitor cell in rabbit meniscus

The repair of meniscus in the avascular zone remains a great challenge, largely owing to their limited healing capacity. Stem cells based tissue engineering provides a promising treatment option for damaged meniscus because of their multiple differentiation potential. We hypothesized that meniscus-derived stromal cells (MMSCs) may be present in meniscal tissue, and if their pluripotency and character can be established, they may play a role in meniscal healing. To test our hypothesis, we isolated MMSCs, bone marrow-derived stromal cells (BMSCs) and fibrochondrocytes from rabbits. In order to avoid bone marrow mesenchymal stromal cell contamination, the parameniscal tissues and vascular zone of meniscus were removed. The characters of these three types of cells were identified by evaluating morphology, colony formation, proliferation, immunocytochemistry and multi-differentiation. Moreover, a wound in the center of rabbit meniscus was created and used to analyze the effect of BMSCs and MMSCs on wounded meniscus healing. BMSCs & MMSCs expressed the stem cell markers SSEA-4, Nanog, nucleostemin and STRO-1, while fibrochondrocytes expressed none of these markers. Morphologically, MMSCs displayed smaller cell bodies and larger nuclei than ordinary fibrochondrocytes. Moreover, it was certified that MMSCs and BMSCs were all able to differentiate into adipocytes, osteocytes, and chondrocytes in vitro. However, more cartilage formation was found in wounded meniscus filled with MMSCs than that filled with BMSCs. We showed that rabbit menisci harbor the unique cell population MMSCs that has universal stem cell characteristics and posses a tendency to differentiate into chondrocytes. Future research should investigate the mechanobiology of MMSCs and explore the possibility of using MMSCs to more effectively repair or regenerate injured meniscus.

Arthroscopic repair of the meniscal injury using meniscal repair device

BACKGROUND

Total meniscus resection after meniscus tear usually leads to faster degeneration and osteoarthritis of the knee joint. Preservation and repair of the injured menisci are therefore of great clinical importance. The aim of this study was to evaluate the clinical effects of arthroscopic repair of meniscal injuries using the Fast-Fix device.

MATERIALS AND METHODS

96 patients (58 males, 38 females) with mean age of 24.3 years (range 12-46 years)) with a meniscus injury were treated with the Fast-Fix device under arthroscopy between July 2007 and June 2009. The right and left knees were involved in 46 and 50 patients respectively. In 12, 46 and 38 patients, the injury was located in the anterior horn, body and posterior horn respectively. In 38, 45 and 13 patients, it was in the red, red-white, and white regions, respectively. All-inside and outside-in techniques were used for these meniscal injuries. Criteria for successful surgery were no locking pain or swelling and a negative McMurray test.

RESULTS

The mean followup period was 3.7 years (range 2-5 years). The surgical success rate was 91.7% (n = 88). The mean Lysholm score increased from 47.8 ± 10.4 preoperatively to 85.7 ± 12.8 postoperatively. The mean Tegner activity score was 7.4 ± 1.6 (range 5-9) preinjury, 2.1 ± 0.9 (range 0-4) preoperatively and 7.2 ± 2.2 (range 4-10) postoperatively (P < 0.001). A total of 92 patients (95.8%) returned to full-time work. The International Knee Documentation Committee score increased from 32.7 ± 10.7 (range 10.3-51.7) preoperatively to 82.5 ± 5.1 (range 65.1-91.2) postoperatively (P < 0.001).

CONCLUSIONS

The Fast-Fix system is an efficient, safe and effective suture technique for meniscal repair.

The collagen meniscus implant

Lesions in the meniscus occur particularly in young, active patients in the nonvascularized area which, consequently have a bad intrinsic healing capacity. This has a large impact on the mobility and function of the knee joint. Lesions, and partial lesions, lead to the progression of osteoarthritis over time in a large proportion of patients. The only clinical treatment for severe cases so far is an allograft donor meniscus, which is used mostly in patients with severe osteoarthritis with a completely destroyed meniscus. However, this technique still has to be considered as experimental and, thus, is not yet used on a routine basis. Various technical solutions have been advocated to repair meniscus lesions. One solution is to perform a partial meniscectomy and insert a collagen meniscus implant (CMI) at the site of the lesion. However, the initial mechanical properties of the collagen scaffold are inferior to the native meniscus. Therefore, it is only possible to perform a CMI implantation if the peripheral rim of the meniscus is still intact. Histology of preclinical and clinical biopsies of the implanted CMI demonstrated a repopulation of the scaffold by fibrous tissue and in time a remodeling of the fibrous tissue into fibrocartilaginous-like tissue. Based on histology, the ingrowth of new tissue into the CMI might occur by a process of synovial overgrowth, but other mechanisms of revitalization are also possible. Although some clinical studies demonstrated improvement in outcome scores, the number of patients was small in all studies and the positive effect on the prevention of progression of osteoarthritis was not compared with control groups.

Current strategies in meniscal regeneration

The meniscus plays an important role in the biomechanics and tribology of the knee joint. Damage to or disease of the meniscus is now recognized to predispose to the development of osteoarthritis. Treatment of meniscal injury through arthroscopic surgery has become one of the most common orthopedic surgical procedures, and in the United States this can represent 10 to 20% of procedures related to the knee. The meniscus has a limited healing capacity constrained to the vascularized periphery and therefore, surgical repair of the avascular regions is not always feasible. Replacement and repair of the meniscus to treat injuries is being investigated using tissue engineering strategies. Promising as these approaches may be, there are, however, major barriers to overcome before translation to the clinic.

High density type I collagen gels for tissue engineering of whole menisci

This study investigates the potential of high density type I collagen gels as an injectable scaffold for tissue engineering of whole menisci, and compares these results with previous strategies using alginate as an injectable scaffold. Bovine meniscal fibrochondrocytes were mixed with collagen and injected into micro-computed tomography-based molds to create 10 and 20mgml(-1) menisci that were cultured for up to 4weeks and compared with cultured alginate menisci. Contraction, histological, confocal microscopy, biochemical and mechanical analysis were performed to determine tissue development. After 4weeks culture, collagen menisci had preserved their shape and significantly improved their biochemical and mechanical properties. Both 10 and 20mgml(-1) menisci maintained their DNA content while significantly improving the glycosaminoglycan and collagen content, at values significantly higher than the alginate controls. Collagen menisci matched the alginate control in terms of the equilibrium modulus, and developed a 3- to 6-fold higher tensile modulus than alginate by 4weeks. Further fibrochondrocytes were able to reorganize the collagen gels into a more fibrous appearance similar to native menisci.

The effect of IGF-I on anatomically shaped tissue-engineered menisci

This study investigates the effect of insulin-like growth factor (IGF)-I on the development of anatomically-shaped alginate menisci seeded with meniscal fibrochondrocytes. To accomplish this, bovine meniscal fibrochondrocytes were seeded into 2% w/v alginate, crosslinked with calcium sulfate, and injected into anatomical molds derived from microcomputed tomography scans. The meniscal constructs were then cultured for up to 4 weeks with or without 100 ng/mL IGF-I supplemented in the media. Histological, immunohistological, biochemical, and mechanical analyses were performed to characterize tissue development, accumulation and localization of extracellular matrix, and mechanical properties. After 4 weeks of culture, IGF-I treatment significantly improved mechanical and biochemical properties, while maintaining DNA content, with a 26-fold increase in glycosaminoglycan (GAG) content and 10-fold increase in collagen content compared to 0-week controls, and a 3-fold increase in the equilibrium modulus at 2 weeks compared to controls. IGF-I-treated menisci had ∼60% of the GAG content of native tissue and the compressive equilibrium modulus matched native properties by 2 weeks of culture. Further, IGF-I-treated menisci developed a distinct surface layer similar to native tissue with elongated cells and collagen fibers aligned parallel to the surface, the presence of types I and II collagen, and accumulation of lubricin. This study demonstrates that IGF-I treatment can greatly increase the mechanical and biochemical properties of engineered tissues and aid in the development of a distinct surface zone similar to the superficial zone of native menisci.

Tissue engineering for total meniscal substitution: animal study in sheep model--results at 12 months

The aim of the study was to investigate the use of a hyaluronic acid/polycaprolactone material for meniscal tissue engineering and to evaluate the tissue regeneration after the augmentation of the implant with expanded autologous chondrocytes. Eighteen skeletally mature sheep were treated. The animals were divided into three groups: cell-free scaffold, scaffold seeded with autologous chondrocytes, and meniscectomy alone. The implant was sutured to the capsule and to the meniscal ligament. At a 12-month gross assessment, histology and histomorphometry were used to assess the meniscus implant, knee joint, and osteoarthritis development. All implants showed excellent capsular ingrowth at the periphery. The implant gross assessment showed significant differences between cell-seeded and cell-free groups (p=0.011). The histological analysis indicated a cellular colonization throughout the implanted constructs. Avascular cartilaginous tissue formation was significantly more frequent in the cell-seeded constructs. Joint gross assessment showed that sheep treated with scaffold implantation achieved a significant higher score than those underwent meniscectomy (p<0.0005), and the Osteoarthritis Research Society International score showed that osteoarthritic changes were significantly less in the cell-seeded group than in the meniscectomy group (p=0.047), even though results were not significantly superior to those of the cell-free scaffold. Seeding of the scaffold with autologous chondrocytes increases its tissue regeneration capacity, providing a better fibrocartilaginous tissue formation. The study suggests the potential of the novel hyaluronic acid/polycaprolactone scaffold for total meniscal substitution, although this approach has to be further improved before being applied into clinical practice.

Meniscus repair and transplantation: a comprehensive update

Preservation of meniscal tissue is paramount for long-term joint function, especially in younger patients who are athletically active. Many studies have reported encouraging results following repair of meniscus tears for both simple longitudinal tears located in the periphery and complex multiplanar tears that extend into the central third avascular region. This operation is usually indicated in active patients who have tibiofemoral joint line pain and are less than 50 years of age. However, not all meniscus tears are repairable, especially if considerable damage has occurred. In select patients, meniscus transplantation may restore partial load-bearing meniscus function, decrease symptoms, and provide chondroprotective effects. The initial postoperative goal after both meniscus repair and transplantation is to prevent excessive weight bearing, as high compressive and shear forces can disrupt healing meniscus repair sites and transplants. Immediate knee motion and muscle strengthening are initiated the day after surgery. Variations are built into the rehabilitation protocol according to the type, location, and size of the meniscus repair, if concomitant procedures are performed, and if articular cartilage damage is present. Meniscus repairs located in the periphery heal rapidly, whereas complex multiplanar repairs tend to heal more slowly and require greater caution. The authors have reported the efficacy of the rehabilitation programs and the results of meniscus repair and transplantation in many studies.

End-linked, amphiphilic, degradable polymer conetworks: synthesis by sequential atom transfer radical polymerization using a bifunctional, cleavable initiator

End-linked amphiphilic conetworks prepared using an ATRP bifunctional, bis(hemiacetal ester) initiator were hydrolyzed by HCl, yielding novel amphiphilic star copolymers.

Clinical and radiological results 21 years following successful, isolated, open meniscal repair in stable knee joints

The long-term results over 20 years following meniscal repair in stable knees have not been described yet. The objective was therefore to analyze the clinical and radiological outcomes of successful, isolated, open meniscal repairs with an intact ACL after a mean follow-up of 20.6 years (range, 16-25) retrospectively in 26 patients. Clinical evaluation included objective (Lysholm, IKDC, Tegner) and subjective scores. Standard radiological assessment according to Ahlbäck's osteoarthritis classification and weight-bearing full-leg radiography for alignment were performed. Eight patients were excluded due to a re-rupture of the meniscus. In the 18 remaining patients (12 male, 6 female), the mean Lysholm and IKDC score was 97.8 points (range, 85-100) and 93% (range, 77-100) at the most recent follow-up, respectively. The Tegner activity scale averaged 4.2 (range, 3-7). Subjectively, 13 patients rated their outcome excellent, 4 good, and 1 fair. The radiological evaluation demonstrated an average development of "+1" grade (range, 0-"+2") osteoarthritic changes versus preoperatively; however, the contralateral healthy knee also revealed comparable (on average "+1" grade) degenerative changes reflecting natural history. The alignment was not significantly different between the operated and the contralateral leg. Overall, isolated open meniscal repair in stableness has the potential of a successful surgery with good to excellent long-term results. The development of osteoarthritic changes within the femorotibial compartments is mild and comparable to contralateral and the alignment of the axis is preserved. Therefore, repair of a ruptured meniscus is recommended whenever possible, even in isolated meniscal tears. However, a re-rupture rate of approximately 30% in isolated meniscal tears has to be acknowledged, which still reflects the need for biological enhancement of meniscal healing.

The knee meniscus: structure-function, pathophysiology, current repair techniques, and prospects for regeneration

Extensive scientific investigations in recent decades have established the anatomical, biomechanical, and functional importance that the meniscus holds within the knee joint. As a vital part of the joint, it acts to prevent the deterioration and degeneration of articular cartilage, and the onset and development of osteoarthritis. For this reason, research into meniscus repair has been the recipient of particular interest from the orthopedic and bioengineering communities. Current repair techniques are only effective in treating lesions located in the peripheral vascularized region of the meniscus. Healing lesions found in the inner avascular region, which functions under a highly demanding mechanical environment, is considered to be a significant challenge. An adequate treatment approach has yet to be established, though many attempts have been undertaken. The current primary method for treatment is partial meniscectomy, which commonly results in the progressive development of osteoarthritis. This drawback has shifted research interest toward the fields of biomaterials and bioengineering, where it is hoped that meniscal deterioration can be tackled with the help of tissue engineering. So far, different approaches and strategies have contributed to the in vitro generation of meniscus constructs, which are capable of restoring meniscal lesions to some extent, both functionally as well as anatomically. The selection of the appropriate cell source (autologous, allogeneic, or xenogeneic cells, or stem cells) is undoubtedly regarded as key to successful meniscal tissue engineering. Furthermore, a large variation of scaffolds for tissue engineering have been proposed and produced in experimental and clinical studies, although a few problems with these (e.g., byproducts of degradation, stress shielding) have shifted research interest toward new strategies (e.g., scaffoldless approaches, self-assembly). A large number of different chemical (e.g., TGF-β1, C-ABC) and mechanical stimuli (e.g., direct compression, hydrostatic pressure) have also been investigated, both in terms of encouraging functional tissue formation, as well as in differentiating stem cells. Even though the problems accompanying meniscus tissue engineering research are considerable, we are undoubtedly in the dawn of a new era, whereby recent advances in biology, engineering, and medicine are leading to the successful treatment of meniscal lesions.

Dynamic compressive loading of image-guided tissue engineered meniscal constructs

This study investigated the hypothesis that dynamic compression loading enhances tissue formation and increases mechanical properties of anatomically shaped tissue engineered menisci. Bovine meniscal fibrochondrocytes were seeded in 2%w/v alginate, crosslinked with CaSO(4), injected into μCT based molds, and post crosslinked with CaCl(2). Samples were loaded via a custom bioreactor with loading platens specifically designed to load anatomically shaped constructs in unconfined compression. Based on the results of finite element simulations, constructs were loaded under sinusoidal displacement to yield physiological strain levels. Constructs were loaded 3 times a week for 1 h followed by 1 h of rest and loaded again for 1 h. Constructs were dynamically loaded for up to 6 weeks. After 2 weeks of culture, loaded samples had 2-3.2 fold increases in the extracellular matrix (ECM) content and 1.8-2.5 fold increases in the compressive modulus compared with static controls. After 6 weeks of loading, glycosaminoglycan (GAG) content and compressive modulus both decreased compared with 2 week cultures by 2.3-2.7 and 1.5-1.7 fold, respectively, whereas collagen content increased by 1.8-2.2 fold. Prolonged loading of engineered constructs could have altered alginate scaffold degradation rate and/or initiated a catabolic cellular response, indicated by significantly decreased ECM retention at 6 weeks compared with 2 weeks. However, the data indicates that dynamic loading had a strikingly positive effect on ECM accumulation and mechanical properties in short term culture.

Greater than 10-year results of red-white longitudinal meniscal repairs in patients 20 years of age or younger

BACKGROUND

A prospective longitudinal investigation was conducted to determine the long-term outcome of single longitudinal meniscal repairs extending into the central avascular region in patients aged 20 years or younger.

PURPOSE

To determine the long-term success rate and reoperation rate of meniscal repairs extending into the avascular zone.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Thirty-three meniscal repairs were performed using an inside-out multiple vertical divergent suture technique. A concomitant anterior cruciate ligament reconstruction was done in 18 patients. The mean follow-up was 16.8 years (range, 10.1-21.9 years). The long-term success rate was determined in 29 repairs (88%) by the presence of normal or nearly normal parameters from 2 validated knee rating systems, assessment of magnetic resonance imaging and weightbearing posteroanterior radiographs by independent physicians, and follow-up arthroscopy when required. A 3 Tesla magnetic resonance imaging scanner with cartilage-sensitive pulse sequences was used, and T2 mapping was performed. A comparison was made between the short-term (mean, 4 years) and long-term outcomes.

RESULTS

Eighteen (62%) of the meniscal repairs had normal or nearly normal characteristics in all of the parameters assessed. Six repairs (21%) required partial arthroscopic resection, 2 had loss of joint space on radiographs, and 3 that were asymptomatic failed according to magnetic resonance imaging criteria, for a total of 11 documented failures (38%). There was no significant difference in the mean articular cartilage T2 scores in the healed menisci between the involved and contralateral tibiofemoral compartments in the same knee. There were no significant differences between short- and long-term evaluations for pain, swelling, jumping, patient knee condition rating, or the overall Cincinnati rating score.

CONCLUSIONS

A chondroprotective joint effect was demonstrated in the healed menisci repairs, which warrants the procedure in select patients. The long-term evaluation of the anterior cruciate ligament-reconstructed knees with concurrent successful meniscal repairs demonstrated a low rate of radiographic arthritis.

Long-term outcome after meniscal repair

PURPOSE

the purpose of this study was to analyse the clinical and radiological results of meniscal repairs and identify factors that correlate with the success of this procedure.

METHODS

a retrospective review of 119 meniscal repairs was completed. The average follow-up was 70 months. Successful meniscal repairs were observed critically in terms of radiographic changes and clinical outcomes and compared with failed meniscal repairs.

RESULTS

the overall success rate of meniscal repairs was 74%. Meniscal repairs that were performed within 6 weeks of injury had better results (83%) than late repairs (52%). The best results were obtained with the inside-out technique using #0 PDS suture (80%) compared to all-inside Biofix arrows (70%) and combined repairs (63%). Patients with associated ACL injury had a better chance of a successful outcome, but this was only significant when the ACL was reconstructed at the time of repair (P < 0.05). Those patients who had failed meniscal repair had increased radiographic osteoarthritic changes (81%) on long-term follow-up compared to patients with successful repair (14%).

CONCLUSION

this retrospective study shows the clinical and radiological importance of meniscal repair. Successful results in this study were associated with younger age and earlier repair using inside-out technique. Furthermore, increased success was seen in meniscal repairs performed in association with ACL reconstruction.

Maturation state-dependent alterations in meniscus integration: implications for scaffold design and tissue engineering

The knee meniscus is a crucial component of the knee that functions to stabilize the joint, distribute load, and maintain congruency. Meniscus tears and degeneration are common, and natural healing is limited. Notably, few children present with meniscus injuries and other related fibrocartilaginous tissues heal regeneratively in immature animals and in the fetus. In this work, we evaluated fetal, juvenile, and adult bovine meniscus properties and repair capacity in vitro. Although no changes in cell behavior (migration and proliferation) were noted with age, drastic alterations in the density and distribution of the major components of meniscus tissue (proteoglycan, collagen, and DNA) occurred with development. Coincident with these marked tissue changes, the in vitro healing capacity of the tissue decreased with age. Fetal and juvenile meniscus formed a robust repair over 8 weeks on both a histological and mechanical basis, despite a lack of vascular supply. In contrast, adult meniscus did not integrate over this period. However, integration was improved significantly with the addition of the growth factor transforming growth factor-beta 3. Finally, to evaluate engineered scaffold integration in the context of aging, we monitored cellular infiltration from native tissue into engineered nanofibrous constructs. Our findings suggest that maturation processes that enable load bearing in the adult limit endogenous healing potential and identify new metrics for the development of tissue-engineered meniscus implants.

Clinical and second-look arthroscopic evaluation of repaired medial meniscus in anterior cruciate ligament-reconstructed knees

BACKGROUND

Tears of the medial meniscus posterior horn (MMPH) are frequently found in knees with deficient anterior cruciate ligaments (ACLs). There are few studies that have evaluated healing of the menisci and the factors associated with healing.

HYPOTHESIS

The repaired menisci would show good healing in the knees with reconstructed ACLs, and the healing capacity of the menisci would differ according to the size, type, and location of the tear as well as the age and gender.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

From August 1997 to February 2007, 311 knees underwent MMPH repair using either a modified all-inside or inside-out technique with concomitant ACL reconstruction. Among these patients, a second-look arthroscopy was performed at a mean of 37.7 months postoperatively (range, 12-128 months) in 140 patients. Clinical parameters and outcomes were evaluated. The repaired menisci were divided into complete, incomplete, and failure-to-heal groups. The factors associated with meniscal healing were statistically assessed.

RESULTS

Among 140 patients, 118 (84.3%) showed complete healing, 17 (12.1%) had incomplete healing, and 5 (3.6%) failed to heal. The clinical success rate was 96.4% (135/140) because patients in the incomplete group showed no clinical symptoms associated with meniscal tears. Healing was associated with the tear location (P <.001) and type of tear (P =.0237) on the univariate analysis and the location (P =.0401) only on the multivariate analysis.

CONCLUSION

Repaired MMPH tears in knees with reconstructed ACLs healed without complications and had satisfactory clinical results. The tear location and type were factors associated with healing on the univariate analysis and location only on the multivariate analysis.

Repair of meniscal cartilage white zone tears using a stem cell/collagen-scaffold implant

Injuries to the avascular region of knee meniscal cartilage do not heal spontaneously. To address this problem we have developed a new stem cell/collagen-scaffold implant system in which human adult bone marrow mesenchymal stem cells are seeded onto a biodegradable scaffold that allows controlled delivery of actively dividing cells to the meniscus surface. Sandwich constructs of two white zone ovine meniscus discs with stem cell/collagen-scaffold implant in between were cultured in vitro for 40 days. Histomorphometric analysis revealed superior integration in the stem cell/collagen-scaffold groups compared to the cell-free collagen membrane or untreated controls. The addition of TGF-beta1 to differentiate stem cells to chondrocytes inhibited integration. Biomechanical testing demonstrated a significant 2-fold increase in tensile strength in all constructs using the stem cell/collagen-scaffold compared to control groups after 40 days in culture. Integration was significantly higher when collagen membranes were used that had a more open/spongy structure adjacent to both meniscal cartilage surfaces, whereas a collagen scaffold designed for osteoinduction failed to induce any integration of meniscus. In conclusion, the stem cell/collagen-scaffold implant is a potential therapeutic treatment for the repair of white zone meniscal cartilage tears.

Meniscus replacement using synthetic materials

The meniscus plays a critical role in load transmission, stability and energy dissipation in the knee joint. Loss of the meniscus leads to joint degeneration and osteoarthritis. An increased understanding of the degenerative changes that occur after meniscectomy made clear that it is beneficial to save as much meniscal tissue as possible. Meniscal repair has become a standard procedure, and partial resection of damaged menisci should be performed as sparingly as possible. However, not all damaged menisci can be treated by partial resection or by repair, making a total meniscectomy inevitable. In these cases, replacement of the resected meniscal tissue by an implant might avoid the articular cartilage degeneration. Different types of meniscal substitutes, such as allografts, collagen, permanent synthetic scaffolds, and biodegradable scaffolds, have been used in experimental and clinical studies. This review highlights the research on these meniscal substitutes and shows that current research is mainly focused on a biological tissue-engineering approach either with or without additional cell-seeding techniques.

[Complications with all-inside devices used in reconstructive meniscal surgery]

All-inside devices have become increasingly popular in reconstructive meniscal surgery since their introduction at the beginning of the 1990s. Although the latest clinical investigations show better results for conventional suture techniques, meniscal devices are an important alternative because of the low risk of neurovascular injury and the easy handling of the instruments. Over the years, many reports on specific complications related to all-inside devices have been published. Especially chondral injuries, implant loosening, device migration and capsular or neural irritations have been described. Furthermore, some authors reported on foreign body reactions and cystic granulomas after the use of meniscal fixation devices. However, there is no evidence for a higher infection rate or for specific infections after the use of intra-articular techniques. Clinical reports on complications along with biomechanical studies on meniscal repair devices have led to the enhancement of all-inside techniques through substantial modifications of established products as well as to the development of new implants. After reviewing the latest literature, the complication rate seems to be decreasing. In many ways, all-inside devices are an interesting alternative to conventional suture techniques. A precise knowledge of their potential complications and the pitfalls during surgery however is crucial to make a risk evaluation in the choice of the right technique for meniscal reconstruction.

Modified cruciate suture technique for arthroscopic meniscal repair: a technical note

Arthroscopic meniscal repair is the procedure of choice whenever a reparable tear is diagnosed. The cruciate suture for arthroscopic meniscal repair is a type of the outside-in technique. It has advantages like: (1) its ultimate tension load (UTL) is 1.6 times higher than the UTL of the vertical suture (gold standard), (2) it holds the circumferential collagen fibers of the meniscus in a three-dimensional plane compared to the vertical and horizontal sutures which hold the circumferential fibers of the meniscus in a two-dimensional plane, (3) simple instrumentation, (4) could withstand not only distraction forces on the repaired meniscal tear but also, shear forces because of the oblique orientation of the cruciate suture limbs. It has disadvantages like: being difficult to perform and time-consuming. A modified technique is presented in this study which has the following advantages; (1) less time-consuming, (2) performed through a smaller skin incision, (3) a sliding knot is used to tie the cruciate suture.

Complications in medial meniscus suture: a cadaveric study

The aim of this study was to examine the possibility of complications in medial meniscus repair using an inside-out suturing device. Anatomical cadaveric study. Six fresh frozen cadaveric lower limbs were used. The posterior horn of the medial meniscus was sutured using three vertical stitches. An anatomical dissection was subsequently performed to check for any possible effects upon the structures of the medial aspect of the knee. In addition, an incision was made in a safety zone in order to ascertain whether it was possible to carry out the suture without affecting the aforementioned structures. No vascular or nervous structures were pierced by the needle. On knotting, it was found that a number of different structures had become trapped: the sartorial tendon was affected in each of the specimens used. In four cases, the saphenous vein was trapped by some of the knots. The saphenous nerve was trapped in four instances. Once this had been established, a small accessory incision was made to provide access to a safety zone, where suture can be performed without affecting any neurovascular or tendinous structures. Inside-out suture of the posterior meniscal horn carries a high incidence of entrapment of the neurovascular structures of the medial aspect of the knee. The sartorial tendon is constantly affected. Such complications can easily be avoided by entering the safety zone via a small auxiliary incision. This study provides evidence that complications affecting the peripheral structures of the medial aspect of the knee may arise during inside-out suture of the posterior horn of the medial meniscus and proposes a simple method of averting them.

Meniscal repair with biofix arrows: results after 4.7 years' follow-up

BACKGROUND

Absorbable meniscus arrows have, since they were introduced in 1993, become a common all-inside technique in meniscal repair. Potential advantages are conserving the meniscus, simplifying the surgical technique, reducing operating time, and reducing the risk of neurovascular damage. Despite extensive use all over the world, few long-term follow-up studies have been published.

HYPOTHESIS

Meniscus arrows have, based on published material, a rate of success around 80% to 90%.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

The Biofix arrow fixation technique was used in 123 patients in need of meniscal repair from January 1997 to December 2002 at our hospital. The patients underwent an interview by phone, mail, or e-mail during autumn 2004 that included questions about reoperation and Lysholm score. In addition, the operative charts were reviewed.

RESULTS

There were 118 patients (96%) available for the questionnaire, and 45 of these (38%) had had reoperations done because of meniscal rerupture during the follow-up period. Another 3 patients were waiting for meniscal reoperations. In addition, the charts of 2 of those unavailable for the study showed that they had been reoperated, resulting in a total of 41% verified failures. The Lysholm score for the whole study group at follow-up was 85 (range, 36-100). The mean Lysholm score for those who had a second operation was 81 (range, 36-100), and it was 88 (range, 55-100) for the others (P = .009). The mean time between primary operation and reoperation was 17 months (range, 1-75 months). Mean postoperative follow-up was 4.7 years (range, 1.8-7.7 years).

CONCLUSION

Meniscal repair with Biofix arrows has an unacceptably low rate of success.

Meniscal screw fixation provides sufficient stability to prevent tears from gapping

BACKGROUND

Many meniscal fixation implants have low pull-out forces. It is still unknown if these forces are higher than the forces the implants must resist in vivo. It was hypothesized that meniscal repair with the meniscal screw as an example for a device of low pull-out force significantly reduces tear gapping.

METHODS

Longitudinal tears were set in the posterior horn of the medial menisci of porcine knee joints. To observe the tears a translucent placeholder copying the original articular surface replaced the medial tibial plateau. The knees were moved in a loading and motion simulator under various external moments and axial loads and gapping of the tear was registered. The measurements were repeated after fixation of the tears with three ClearFix Screws, which show a low pull-out force of 20N only.

FINDINGS

Maximum gapping (median 1.6mm, min/max 1.1/1.8mm) occurred at 200N axial joint load under the combination of a valgus and external rotation moment. Fixation with the ClearFix Screw significantly reduced tear gapping in all load cases.

INTERPRETATION

Moderate joint loads only lead to small gaps of meniscal tears. Meniscal fixation with the ClearFix Screw prevents longitudinal meniscal tears from gapping. This could indicate from a biomechanical point of view that fixation implants of low pull-out strength are not in danger of failure in a normal rehabilitation regimen.

Distraction forces on repaired bucket-handle lesions in the medial meniscus

BACKGROUND

Numerous studies have investigated the biomechanical properties of meniscal repair techniques. One of the most commonly discussed parameters is the failure load in the axis of insertion, although little is known about the distraction forces actually occurring at repaired bucket-handle lesions.

HYPOTHESIS

There are clinically relevant distraction forces on repaired meniscus bucket-handle lesions.

STUDY DESIGN

Controlled laboratory study.

METHODS

Meniscus bucket-handle lesions were created and repaired in human cadaveric knees with a vertical suture made from a braided steel wire. A small-sized load sensor was connected to the wire at the periphery of the meniscus. The distraction forces acting on the lesion were measured at different knee joint angles (0 degrees -120 degrees of flexion) with internal and external rotation and with and without weight loading. Forces in excess of 10 N were considered to have clinical relevance.

RESULTS

Mean forces on the meniscus repair ranged from 1.64 to 4.72 N. Irrespective of the modalities (ie, different flexion angles, weight load, direction of rotation), it was found that the forces were well below the cutoff value of 10 N (P < .01). Increasing flexion angles generally did not cause an increase in distraction forces.

CONCLUSION

The data suggest that distraction forces are not the primary factor in the mechanical stability of meniscal repair. It must therefore be assumed that other factors such as shear forces are of greater significance.

CLINICAL RELEVANCE

The results may help to validate the biomechanical properties of different meniscal repair techniques.

Histoacryl glue in meniscal repairs (a biomechanical study)

The purpose of this study was to investigate the biomechanical efficacy of Histoacryl (cyanoacrylate, N-asetil 2 butyl sistein) in meniscal tear repair. In our study, the primary stability of three different repair techniques in delaying the formation of a gap of 2 mm was investigated. A meniscal tear was repaired with two vertical sutures and Histoacryl in the first group; it was repaired only with Histoacryl in the second group, and with only two vertical sutures in the third group. Menisci were then placed in a tensile loading machine, and the primary stability of the repair zones was measured until a displacement of 2 mm occurred. Biomechanical force was significantly (P<0.05) high (112.0+/-17.20 N) in all groups when vertical suture and Histoacryl glue were used together during displacements of 0.5, 1.0, 1.5 and 2.0 mm. We believe that Histoacryl is superior to vertical sutures regarding gap delaying. It potentiates the effect of vertical suture strength, permits early motion and thus merits an in vivo study.

Trinion meniscal screw

All-inside meniscal repair devices require no accessory incisions, allow faster repairs, and are widely used. The purpose of this study was to determine the in vitro load to failure strength of one new recently released meniscal repair device. Using an established protocol, a vertical longitudinal tear 3 mm from the meniscus periphery was created in 15 porcine menisci and each tear repaired by a single 10-mm Trinion meniscal screw. This repair was pulled apart with loads parallel to the repair axis. Loads to failure and modes of failure were evaluated. The mean load to failure was 38.9 N (SD +/- 9.04) (range, 23.1 to 55.2 N). Two modes of failure were observed: puling out of the inner piece (6 of 15) and of the outer (peripheral) rim (9 of 15). No devices broke. The Trinion meniscal screw is a dual-head design made of trimethylene carbonate, poly L-lactic acid, and poly D, L lactic acid. Its load to failure is similar to other tested devices. The mechanisms of failure were consistent with other all-inside meniscal repair devices. The material properties of a repair device are only one indication of device performance and may not correlate with clinical results.

Midterm results of meniscal repair using the BioStinger meniscal repair device

PURPOSE

The purpose of this study was to evaluate the midterm healing rate and any adverse events from meniscus repair using the BioStinger meniscus repair device (Linvatec, Largo, FL).

METHODS

A retrospective review of a consecutive series of meniscal repairs performed by a single surgeon using the BioStinger was conducted. The BioStinger is cannulated, made of molded poly L-lactic acid, and inserted over a needle into the meniscus tissue. Clinical results and adverse events were noted, and Lysholm, Tegner, Cincinnati, and International Knee Documentation Committee (IKDC) activity scores were obtained on all patients.

RESULTS

Forty-one patients underwent 41 meniscal repairs with an average follow-up of 38.6 months (range, 24 to 69 months); 35 meniscus repairs were performed in conjunction with anterior cruciate ligament reconstruction and 6 in stable knees. Tears repaired were peripheral, posterior horn tears with an average length of 2 cm. Clinical evidence of meniscal healing was observed in 95% at the time of last follow-up. Six second-look arthroscopies were performed and 2 failures were found. All other patients were symptom free. At follow-up, the mean Tegner score was 6.1 (2.8 preoperative), IKDC activity score was 3.3 (2.1 preoperative), Lysholm score was 90.6 (48.7 preoperative), and the mean Cincinnati score was 86.7 (41.3 preoperative). Four patients had peripheral migration of the device without skin tenting or perforation; 3 underwent removal of the BioStinger from the soft tissues and the other resolved after 12 months.

CONCLUSIONS

The midterm clinical success rate was 95% using the BioStinger device. Adverse events were observed in few cases.

LEVEL OF EVIDENCE

Level IV, cases series.

Evaluation of Engineered Meniscal Cartilage Constructs Based on Different Scaffold Geometries Using Magnetic Resonance Imaging and Spectroscopy

Magnetic resonance imaging (MRI) and spectroscopy (MRS) were used to evaluate the properties different scaffold geometries for the production of bioartificial meniscal cartilage constructs. Engineered were generated in perfusion bioreactors from mature sheep meniscal fibrochondrocytes,scaffolds cut from a knitted polyethylene therephtalate (PET) fabric, with a distribution of fibers, 50 microm pores and a density of 45 mg/cm(3) (NF scaffolds), and from two versions of this fabric, which included larger pore sizes (1500 x 500 microm(2)) and densities of (sIV scaffolds) and 83 mg/cm(3) (sV scaffolds). MRI methods were used to determine the permeability the constructs to a low molecular weight MR contrast agent and to measure the macroscopic of medium through and around the constructs. These parameters were correlated with measurements of cell growth and cellular energetics. Cell-free sIV scaffolds were 2- and 5-more porous to flow than the empty sV and NF scaffolds, respectively. These scaffolds, after days of cell growth, were also more permeable to an MR contrast agent. sIV scaffolds yielded(n = 9) with higher cellularities (41 +/- 1%) compared with NF (32 +/- 1%, p < 0.0001) and sV (30 +/- 1%, p < 0.0001) and, when normalized to cell numbers, demonstrated proportionally levels of nucleoside triphosphates (NTP), indicating increased cell viability. Scaffold geometry a marked effect on the properties of engineered meniscal cartilage. MRI and MRS are powerful techniques that can be used to optimize the design of engineered meniscal cartilage and that could be used subsequently to evaluate clinical outcome postimplantation.

Compressive loads in longitudinal lateral meniscus tears: a biomechanical study in porcine knees

PURPOSE

To determine the displacement forces across a lateral meniscal tear during motion.

TYPE OF STUDY

Experimental laboratory biomechanical study.

METHODS

A middle third longitudinal lateral meniscal cut was created arthroscopically at the "red-white" junction in 5 intact porcine knees. With a pressure transducer in the tear, the knees were repeatedly cycled through a full range of motion. Pressure data were gathered with the knees held at neutral, internal rotation (IRot), and external rotation (ERot) and matched to the specific flexion angle measured by electronic goniometer. Averaged pressure measurements were calculated at each 5 degrees interval.

RESULTS

The highest pressures were seen at full extension (neutral, 589 mm Hg; IRot, 1,110 mm Hg; ERot, 337 mm Hg) and declined to a low at 90 degrees of flexion (neutral, 133 mm Hg; IRot, 314 mm Hg; ERot, 187 mm Hg). Then the pressures increased steadily after 100 degrees as the knees were further flexed. The highest pressure was always seen with IRot. IRot during flexion resulted in higher lateral meniscus compressive loads than ERot.

CONCLUSIONS

This model demonstrated that a middle third longitudinal lateral meniscal cut is compressed throughout the full range of knee motion. At no time were negative intrameniscal tear pressures registered that would suggest meniscal cut separation.

CLINICAL RELEVANCE

These data suggest that meniscal compressive loads, not distractive loads, occur throughout knee flexion and extension. The absence of distractive loads across a meniscal cut suggests that the ability of a repair to align the meniscal fragment may be more important than a high load to failure strength.

Comparative spatial and temporal localisation of perlecan, aggrecan and type I, II and IV collagen in the ovine meniscus: an ageing study

This is the first study to immunolocalise perlecan in meniscal tissues and to demonstrate how its localisation varied with ageing relative to aggrecan and type I, II and IV collagen. Perlecan was present in the middle and inner meniscal zones where it was expressed by cells of an oval or rounded morphology. Unlike the other components visualised in this study, perlecan was strongly cell associated and its levels fell significantly with age onset and cell number decline. The peripheral outer meniscal zones displayed very little perlecan staining other than in small blood vessels. Picrosirius red staining viewed under polarised light strongly delineated complex arrangements of slender discrete randomly oriented collagen fibre bundles as well as transverse, thick, strongly oriented, collagen tie bundles in the middle and outer meniscal zones. The collagen fibres demarcated areas of the meniscus which were rich in anionic toluidine blue positive proteoglycans; immunolocalisations confirmed the presence of aggrecan and perlecan. When meniscal sections were examined macroscopically, type II collagen localisation in the inner meniscal zone was readily evident in the 2- to 7-day-old specimens; this became more disperse in the older meniscal specimens. Type I collagen had a widespread distribution in all meniscal zones at all time points. Type IV collagen was strongly associated with blood vessels in the 2- to 7-day-old meniscal specimens but was virtually undetectable at the later time points (>7 month).