Hagmeijer, Michella H.

Meniscus injury and meniscectomy are strongly related to osteoarthritis, thus there is a clinical need for meniscus replacement. The purpose of this study is to create a meniscus scaffold with micro-scale circumferential and radial fibres suitable for a one-stage cell-based treatment. Poly-caprolactone-based scaffolds with three different architectures were made using melt electrowriting (MEW) technology and their in vitro performance was compared with scaffolds made using fused-deposition modelling (FDM) and with the clinically used Collagen Meniscus Implants® (CMI®). The scaffolds were seeded with meniscus and mesenchymal stromal cells (MSCs) in fibrin gel and cultured for 28 d. A basal level of proteoglycan production was demonstrated in MEW scaffolds, the CMI®, and fibrin gel control, yet within the FDM scaffolds less proteoglycan production was observed. Compressive properties were assessed under uniaxial confined compression after 1 and 28 d of culture. The MEW scaffolds showed a higher Young’s modulus when compared to the CMI® scaffolds and a higher yield point compared to FDM scaffolds. This study demonstrates the feasibility of creating a wedge-shaped meniscus scaffold with MEW using medical-grade materials and seeding the scaffold with a clinically-feasible cell number and -type for potential translation as a one-stage treatment.

Objectives: Meniscus repair is desirable over resection to prevent post-meniscectomy arthritis, especially in young and active patients. However, long-term data is currently lacking following isolated meniscus repair, particularly in the pediatric population. The purpose of this study was to report long-term follow-up of isolated meniscus tears treated by meniscus repair in a pediatric population, and to compare those results to previous mid-term follow-up data reported. We hypothesized that these patients would have satisfactory function and reoperation rates at long-term follow-up. Methods: Patients less than 18 undergoing repair of an isolated (without concomitant ACL injury) meniscus tear performed between 1990 and 2005 were included. At the time of final followup, recurrent tear, reoperations, and IKDC and Tegner scores were determined. With logistic regression, the overall failure between different tear types was calculated. Wilcoxon signed ranks tests were performed to calculate the differences in clinical outcome for different time-points, and Spearman coefficients were calculated for Tegner and IKDC with different variables. Results: At an average followup of 17.6 years (13.1 - 26.0 years), 32 patients with 33 isolated meniscus repairs (29 M: 3F) with an average age of 16.1 (9.9 - 18.7) were included in this study. At early follow-up, complex tears (80%) had a higher overall failure rate compared to simple tears (18.2%). However, no further failures occurred since mid-term follow-up with any tear type. At final follow-up, the average IKDC score was 92.3, which was significantly increased when compared to both preoperative 65.3 (p< 0.0001) and mid-term scores, 90.2 (p= 0.01). However, the average Tegner score (6.5) was significantly lower than both pre-operative 8.3 (p< 0.0001) and mid-term 8.4 (p< 0.0001) scores. There was no correlation for Tegner or IKDC values with any risk factors. Conclusion: In conclusion, this study demonstrates overall good to excellent long-term clinical outcomes following isolated meniscus repair in a pediatric population. Early failure and reoperation rates were variable depending on tear type, with complex multiplanar tears having more failures at short-term follow-up. However, at long-term follow-up, IKDC and Tegner scores were not significantly different for those with complex tears compared to other tear types.

Background: Anterior cruciate ligament (ACL) injury is one of the most frequent orthopaedic injuries and reasons for time loss in sports and carries significant implications, including posttraumatic osteoarthritis (OA). Instability associated with ACL injury has been linked to the development of secondary meniscal tears (defined as tears that develop after the initial ACL injury). To date, no study has examined secondary meniscal tears after ACL injury and their effect on OA and arthroplasty risk. Purpose: To describe the rates and natural history of secondary meniscal tears after ACL injury and to determine the effect of meniscal tear treatment on the development of OA and conversion to total knee arthroplasty (TKA). Study Design: Cohort study; Level of evidence, 3. Methods: A geographic database of >500,000 patients was reviewed to identify patients with primary ACL injuries between January 1, 1990, and December 31, 2005. Information was collected with regard to ACL injury treatment, rates/characteristics of the secondary meniscal tears, and outcomes, including development of OA and conversion to TKA. Kaplan-Meier and adjusted multivariate survival analyses were performed to test for the effect of meniscal treatment on survivorship free of OA and TKA. Results: Of 1398 primary ACL injuries, the overall rate of secondary meniscal tears was 16%. Significantly lower rates of secondary meniscal tears were noted among patients undergoing acute ACL reconstruction within 6 months (7%) as compared with patients with delayed ACL reconstruction (33%, P < .01) and nonoperative ACL management (19%, P < .01). Of the 235 secondary meniscal tears identified (196 patients), 11.5% underwent repair, 73% partial meniscectomy, and 16% were treated nonoperatively. Tears were most often medial in location (77%) and complex in morphology (56% of medial tears, 54% of lateral tears). At the time of final follow-up, no patient undergoing repair of a secondary meniscal tear (0%) underwent TKA, as opposed to 10.9% undergoing meniscectomy and 6.1% receiving nonoperative treatment ( P = .28). Conclusion: Secondary meniscal tears after ACL injury are most common among patients undergoing delayed surgical or nonoperative treatment of their primary ACL injuries. Secondary tears often present as complex tears of the medial meniscus and result in high rates of partial meniscectomy.

Background: Meniscal repair is desirable over resection to prevent postmeniscectomy arthritis, especially among young and active patients. However, long-term data are currently lacking following isolated meniscal repair, particularly in the pediatric population. Purpose/Hypothesis: To report long-term follow-up of isolated meniscal tears treated by meniscal repair in a pediatric and adolescent population and to compare those results with previous midterm follow-up data reported. The authors hypothesized that these patients would have satisfactory function and reoperation rates at long-term follow-up. Study Design: Case series; Level of evidence, 4. Methods: Forty-four patients aged ≤18 years undergoing repair of an isolated meniscal tear (without concomitant anterior cruciate ligament injury) between 1990 and 2005 were included. At the time of final follow-up, recurrent tear, reoperations, and International Knee Documentation Committee (IKDC) and Tegner scores were determined. With logistic regression, the overall failure among tear types was calculated. Wilcoxon rank sum analysis were performed to calculate the differences in clinical outcome for different time points, and Spearman coefficients were calculated for Tegner and IKDC with different variables. Results: At a mean follow-up of 17.6 years (range, 13.1-25.9 years), 32 patients with 33 isolated meniscal repairs (29 male, 3 female) with a mean age of 16.1 years (range, 9.9-18.7 years) at surgery were included in this study. At early follow-up, the overall failure rate was 14 of 33 (42%); complex tears (80%) and bucket-handle tears (47%) had higher overall failure rates when compared with simple tears (18.2%), although only complex tears had a significantly higher failure rate. However, no further failures occurred since midterm follow-up with any tear type. At final follow-up, the mean IKDC score was 92.3, which was significantly increased when compared with preoperative (65.3, P < .0001) and midterm (90.2, P = .01) scores. The mean Tegner score (6.5) was significantly lower than both preoperative (8.3, P < .0001) and midterm (8.4, P < .0001) scores. There was no difference in Tegner or IKDC score for patients with successful versus failed repair. Conclusion: In conclusion, while there was a high early failure rate, this study demonstrated overall good to excellent long-term clinical outcomes after isolated meniscal repair in an adolescent population, even for those requiring reoperation. Early failure and reoperation rates were variable, depending on tear type, with complex multiplanar tears having more failures at short-term follow-up. However, at long-term follow-up, IKDC and Tegner scores were not significantly different for those with complex tears as compared with other tear types.

Purpose: To test the technical aspects and feasibility of seeding a combination of meniscus cells isolated from a rapid digestion protocol and mesenchymal stromal cells (MSCs) (20:80 ratio) into a meniscus scaffold for the development of a one-stage arthroscopic procedure for meniscus regeneration. Methods: A cadaveric study was performed using nine fresh frozen human cadaveric knee joints. Two different arthroscopic cell-seeding methods were applied to the Collagen Meniscus Implant (CMI ® ) as carrier scaffold: either (1) seeding before arthroscopic surgical implantation of the scaffold or (2) after implantation of the scaffold. The cells were injected inside the scaffold, using fast green-stained fibrin glue as carrier, to macroscopically visualize the amount of fibrin glue. Macroscopic pictures and confocal microscopy analyses were used to determine cell distribution and viability. In addition, the DNA content in the cell-seeded scaffold was determined. In addition, different concentrations of Liberase were examined to find the optimal concentration for rapid digestion of meniscus tissue. Results: Macroscopically, seeding before implantation showed a better distribution of fast green-stained fibrin glue carrier than seeding the scaffold before surgical implantation. In addition, it resulted in significantly more cells and a better cell distribution compared with seeding the scaffold after arthroscopic implantation. Both seeding methods did not affect cell viability. After rapid digestion, 0.0125% Liberase resulted in the highest cell isolation efficiency. Conclusions: This study demonstrates that living human meniscus cells can be isolated efficiently, combined with MSCs in 20:80 ratio, and uniformly delivered into a currently available meniscus scaffold. This scaffold can then be arthroscopically implanted, creating a one-stage solution for partial meniscal deficiency. Impact Statement Meniscus injury remains the most common indication for orthopedic surgery, but loss of functioning meniscus tissue is strongly correlated with development of early osteoarthritis. However, current clinical options for tissue engineering of the meniscus are limited. This study demonstrates the feasibility of combining human meniscus cells with mesenchymal stromal cells to enhance a meniscus scaffold for meniscus regeneration in a one-stage solution for partial meniscal deficiency.

Background: Meniscal repair is desirable over resection to prevent post-meniscectomy arthritis, especially in young and active patients. However, long-term data is currently lacking following meniscus repair, particularly in the pediatric population. Purpose: To report long-term follow-up of isolated meniscus tears treated by meniscal repair in a pediatric population, and to compare those results to previous mid-term follow-up data reported. We hypothesized that these patients would have satisfactory function and reoperation rates at long-term follow-up. Methods: Patients less than 18 that had a meniscal repair procedure performed between 1990 and 2005 were included. Concomitant ACL reconstructions were excluded from the present study. At the time of final follow-up, recurrent meniscus tear, reoperation rates, and IKDC and Tegner scores were determined. Wilcoxin signed ranks tests were performed to calculate the differences in clinical outcome for the 3 time points (pre-operative, average 7 years post-op, and average 18 years post-op) and Spearman coefficients were calculated for Tegner and IKDC with different variables. Results: At an average follow-up of 18 years (range 13.2 - 25.9 years), 34 patients with 35 isolated meniscus repairs (4F: 30 M) with an average age of 16 (9.9 - 18.7) were included in this study. Of the 35 knees (34 patients), none had “failed” or re-injured their affected meniscus since mid-term follow-up in 2008. The average IKDC score was 92.1 which was found to be significantly increased when compared to both preoperative IKDC 64.7 (P<.0001) and mid-term IKDC scores, 89.8 (p=.02). However, the average Tegner score (6.5) was significantly lower than both pre-operative 8.28 (p<.0001) and the mid-term Tegner average 8.25 (p<.0001). Patients with a meniscus re-tear and subsequent partial meniscectomy had lower IKDC scores than clinically successful repairs (88.9 vs 94.0), but this did not reach statistical significance (p=.09). There was no correlation for Tegner or IKDC values with 1) rim width, 2) current age, 3) time elapsed since surgery, or 4) time from injury to surgery. There were also no differences in Tegner or IKDC scores when comparing; medial versus lateral, left versus right, tear types, surgical repair technique, or male vs female. Conclusion: This study demonstrates very good clinical long-term outcomes following meniscal repair in a pediatric population.