Cyclic test comparison of all-inside device and inside-out sutures for radial meniscus lesion repair: an in vitro porcine model study

Animal models used in meniscal repair research from ex vivo to in vivo: A systematic review

This systematic review, registered with Prospero, aims to identify an optimal animal model for meniscus repair research, moving from ex vivo experimentation to in vivo studies. Data sources included PubMed, Medline, all Evidence-Based Medicine Reviews, Web of Science, and Embase searched in March 2023. Studies were screened using Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Extracted data including animal model, type of experiment, type of tear, surgical techniques, and measured outcomes, were recorded, reviewed, and analyzed by four independent reviewers. The SYstematic Review Centre for Laboratory animal Experimentation (SYRCLE) Rob tool was used for critical appraisal and risk of bias assessment. Out of 11,719 studies, 72 manuscripts were included for data extraction and analysis; 41 ex vivo extra-articular studies, 20 ex vivo intra-articular studies, and only 11 in vivo studies. Six animal models were employed: porcine, bovine, lapine, caprine, canine, and ovine. Longitudinal lesions were the most frequently studied tear pattern and sutures the most common repair technique. Studied outcomes focused mainly on biomechanical assessments and gross observations. This systematic review can guide researchers in their choice of animal model for meniscus repair research; it highlighted the strengths of the porcine, caprine, and bovine models for ex vivo cadaveric studies, while the porcine and caprine models were found to be more suited to in vivo studies due to their similarities with human anatomy. Research teams should familiarize themselves with the advantages and disadvantages of various animal models before initiating protocols to improve standardization in the field.

Reconstruction of medial meniscus posterior portion deficiency in pigs with an autologous patellar tendon graft: an experimental study

OBJECTIVE

This study was performed to investigate the effectiveness of two surgical procedures, autologous patellar tendon graft reconstruction and trans-tibial plateau pull-out repair, using a pig model. The primary focus was to assess the repair capability of medial meniscus posterior portion (MMPP) deficiency, the overall structural integrity of the meniscus, and protection of the femoral and tibial cartilage between the two surgical groups. The overall aim was to provide experimental guidelines for clinical research using these findings.

METHODS

Twelve pigs were selected to establish a model of injury to the MMPP 10 mm from the insertion point of the tibial plateau. They were randomly divided into three groups of four animals each: reconstruction (autologous tendon graft reconstruction of the MMPP), pull-out repair (suture repair of the MMPP via a trans-tibial plateau bone tunnel), and control (use of a normal medial meniscus as the negative control). The animals were euthanized 12 weeks postoperatively for evaluation of the meniscus, assessment of tendon bone healing, and gross observation of knee joint cartilage. The tibial and femoral cartilage injuries were evaluated using the International Society for Cartilage Repair (ICRS) grade and Mankin score. Histological and immunohistochemical staining was conducted on the meniscus-tendon junction area, primary meniscus, and tendons. The Ishida score was used to evaluate the regenerated meniscus in the reconstruction group. Magnetic resonance imaging (MRI) was used to evaluate meniscal healing.

RESULTS

All 12 pigs recovered well after surgery; all incisions healed without infection, and no obvious complications occurred. Gross observation revealed superior results in the reconstruction and pull-out repair groups compared with the control group. In the tibial cartilage, the reconstruction group had ICRS grade I injury whereas the pull-out repair and control groups had ICRS grade II and III injury, respectively. The Mankin score was significantly different between the reconstruction and control groups; histological staining showed that the structure of the regenerated meniscus in the reconstruction group was similar to that of the original meniscus. Immunohistochemical staining showed that the degree of type I and II collagen staining was similar between the regenerated meniscus and the original meniscus in the reconstruction group. The Ishida score was not significantly different between the regenerated meniscus and the normal primary meniscus in the reconstruction group. MRI showed that the MMPP in the reconstruction and pull-out repair groups had fully healed, whereas that in the control group had not healed.

CONCLUSION

Autologous patellar tendon graft reconstruction of the MMPP can generate a fibrocartilage-like regenerative meniscus. Both reconstruction and pull-out repair can preserve the structural integrity of the meniscus, promote healing of the MMPP, delay meniscal degeneration, and protect the knee cartilage.

More Is Not Merrier: Increasing Numbers of All-Inside Implants Do Not Correlate with Higher Odds of Revision Surgery

The purpose of this study was to evaluate the relationship between the number of all-inside meniscal repair implants placed and the risk of repair failure. We hypothesized that the use of higher numbers of all-inside meniscus repair implants would be associated with increased failure risk. A retrospective chart review identified 351 patients who underwent all-inside meniscus repair between 2006 and 2013 by a sports medicine fellowship-trained orthopaedic surgeon at a single institution. Patient demographics (age, body mass index [BMI], sex) and surgical data (number of implants used, concomitant anterior cruciate ligament reconstruction [cACLR], and tear type/size/location) were recorded. Patients who received repairs in both menisci or who had follow-up < 1-year postoperatively were excluded. Repair failure was identified through chart review or patient interviews defined as a revision surgery on the index knee such as partial meniscectomy, total knee arthroplasty, meniscus transplant, or repeat repair. Logistic regression modeling was utilized to evaluate the relationship between the number of implants used and repair failure. A total of 227 all-inside meniscus repairs were included with a mean follow-up of 5.0 ± 3.0 years following surgery. Repair failure was noted in 68 knees (30.3%)-in 28.1% of knees with fewer than four implants and in 35.8% of knees with four or more implants (p = 0.31). No significant increase in failure was observed with increasing number of all-inside medial (odds ratio [OR]: 1.15; 95% confidence interval [CI]: 0.79-1.7; p = 0.46) or lateral (OR: 0.86; 95% CI: 0.47-1.57; p = 0.63) implants after controlling for patient age, BMI, cACLR, tear type, or size. Tears of the lateral meniscus located in the red-white and white-white zones had lower odds of failure (OR: 0.14; 95% CI: 0.02-0.88; p = 0.036) than tears within the red-red zone, and patients with cACLR had lower odds of repair failure (OR: 0.40; 95% CI: 0.18-0.86, p = 0.024) than those without. The number of all-inside implants placed during meniscus tear repair did not affect the likelihood of repair failure leading to reoperation after controlling for BMI, age, tear type, size, location, and cACLR. LEVEL OF EVIDENCE:  III.

Several Techniques Exist With Favorable Biomechanical Outcomes in Radial Meniscus Tear Repair-A Systematic Review

PURPOSE

To compare biomechanical properties of various radial tear repair techniques in the medial and lateral menisci.

METHODS

A search was performed for key words regarding mechanical properties of repair of radial meniscal tears in PubMed, Embase, CINAHL, Scopus, and Cochrane databases, yielding 1791 articles. Articles were screened using Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines against inclusion criteria and underwent Methodological Index for Non-Randomized Studies (MINORS) methodologic quality assessment. Repair constructs evaluated were classified based on repair technique, use of a transtibial augmentation, and the number, orientation, and pattern of stitches. Results published across different studies were compared but not subjected to meta-analysis due to variability in testing procedures and heterogeneity of repair methods.

RESULTS

We identified 20 studies that performed mechanical testing on 21 different radial meniscal tear repair techniques. The greatest reported mean load-to-failure (LtF) were the transtibial 2-tunnel + 4 horizontal inside-out sutures (191.2 N ± 17.3, cadaver) and all-inside double vertical repair (146.3 N ± 36.2, porcine). The transtibial technique improved LtF and displacement of an inside-out (IO) horizontal repair. All-inside vertical repairs demonstrated greater LtF, stiffness, and displacement compared with IO horizontal repairs in 2 studies. Compared with IO double horizontal repairs, all-inside double vertical or IO double horizontal repairs with reinforcing stitches parallel to the tear exhibited greater LtF in 3 studies and stiffness in 2 studies. Two studies reported that parallel reinforcing stitches significantly reduced suture tear-through compared with similar, nonreinforced repairs. Mean MINORS score for all studies analyzed was 19.88 ± 1.47 points.

CONCLUSIONS

A systematic review demonstrated that there may be alternatives to traditional IO horizontal repairs for radial meniscus tears. Less-invasive all-inside vertical techniques reinforced with suture parallel to the tear instead of standard IO horizontal sutures may improve strength of repair. In addition, transtibial 2-tunnel augmentation may also increase strength of radial meniscus tear repairs.

CLINICAL RELEVANCE

There may be alternatives to IO horizontal repairs for radial meniscus tears.

Repair Technique for Displaced Meniscal Flap Tears Indicated by MRI Comma Sign

The meniscus comma sign has been described for displaced flap tears of the meniscus. These meniscus tears are displaced into the tibia or femoral recesses and can be often difficult to diagnose intraoperatively. We describe the technique of diagnosis and treatment of a large displaced lateral meniscus flap tear, presenting as a meniscus comma sign. The identification of the meniscus comma sign on consecutive magnetic resonance imaging (MRI) cuts suggest a flap tear of a significant size that indicates reparability. The technique would be to lift the meniscus flap from the meniscotibial recess, reduce it and then repair it with an all-inside meniscus repair or by hybrid meniscus repair techniques.

Placement of sutures for inside-out meniscal repair: both sutures through meniscal tissue reduces displacement on cyclical loading

Purpose

The inside-out meniscal repair is widely performed to preserve the function of meniscus. In this technique, the outer suture is passed through the capsule as well as the outer meniscus, while the inner suture is inserted into the meniscus. The aim of this study was to biomechanically compare the suture stability between meniscus-meniscus and meniscus-capsule suture methods for the longitudinal meniscal tear with inside-out technique.

Methods

Twenty-seven porcine knees were dissected to maintain the femur-medial capsule/meniscus-tibia complex, and the inner meniscus was cut off along the meniscus circumferential fiber with 3 mm width of the peripheral meniscus preserved. After one needle with a 2-0 polyester suture was inserted into the inner portion of the meniscus, the other needle was inserted through 1) the peripheral meniscus (Group A), 2) capsule just above the meniscus (Group B), and 3) capsule at 10 mm apart from the meniscus-capsule junction (Group C) in the inside-out manner. Then, the suture was manually tied on the capsule. The suture gap at the repair site during 300 times of cyclic loading and the ultimate failure load in the load-to-failure test were measured. The statistical significance of the data between two groups in each combination was considered by Bonferroni correction, following a one-way analysis of variance.

Results

In the cyclic loading test, the suture gap was 0.68 ± 0.26 mm in Group A, 1.08 ± 0.36 mm in Group B, and 1.94 ± 0.57 mm in Group C with a significant difference. In the load-to-failure test, the ultimate failure load was 59.1 ± 13.6 N in Group A, 60.0 ± 7.9 N in Group B, and 57.4 ± 4.7 N in Group C, and there was no significant difference.

Conclusion

The stitching region in the inside-out technique for longitudinal meniscal tear affected the stability of the tear site, and stitching the mid-substance region of the meniscus provides good stability in response to cyclic tensile loading. In addition, the stitching region did not affect the ultimate failure load.

Clinical relevance

In the inside-out meniscal repair, the outer suture should be inserted into the remaining peripheral meniscus or the capsule near the meniscus.

Platelet-Rich Plasma Augmentation for Isolated Arthroscopic Meniscal Repairs Leads to Significantly Lower Failure Rates: A Systematic Review of Comparative Studies

Background:

Studies have reported relatively high failure rates of isolated meniscal repairs. Platelet-rich plasma (PRP) has been suggested as a way to increase growth factors that enhance healing.

Purpose:

To compare (1) meniscal repair failures and (2) patient-reported outcomes after isolated arthroscopic meniscal repair augmented with and without PRP.

Study Design:

Systematic review; Level of evidence, 3.

Methods:

A systematic review was performed using the PRISMA (Preferred Reporting Items for Systematic Meta-Analyses) guidelines. Multiple databases were searched for studies that compared outcomes of isolated arthroscopic meniscal repair augmented with PRP versus without PRP in human patients. Failures and patient-reported outcome scores were reported for each study and compared between groups. Study heterogeneity was assessed using I² for each outcome measure before meta-analysis. Study methodological quality was analyzed. Continuous variable data were reported as mean and standard deviation from the mean. Categorical variable data were reported as frequency with percentage. All P values were reported with significance set at P < .05.

Results:

Five articles were analyzed (274 patients [110 with PRP and 164 without PRP]; 65.8% male; mean age, 29.1 ± 4.6 years; mean follow-up, 29.2 ± 22.1 months). The risk of meniscal repair failure ranged from 4.4% to 26.7% for PRP-augmented repairs and 13.3% to 50.0% for repairs without PRP. Meniscal repairs augmented with PRP had significantly lower failure rates than repairs without PRP (odds ratio, 0.32; 95% CI, 0.12-0.90; P = .03). One of the 5 studies reported significantly higher outcomes in the PRP-augmented group versus the no-PRP group for the International Knee Documentation Committee (IKDC), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and Knee injury and Osteoarthritis Outcome Score (KOOS) (P < .05 for all). The remaining 4 studies reported no significant difference between groups with regard to outcomes for the IKDC, Lysholm knee scale, visual analog scale for pain, or Tegner activity level.

Conclusion:

Although the studies were of mostly of low quality, isolated arthroscopic meniscal repairs augmented with PRP led to significantly lower failure rates (10.8% vs 27.0%; odds ratio, 0.32; P = .03) as compared with repairs without PRP. However, most studies reported no significant differences in patient-reported outcomes.

Updates and Advances in the Management of Lateral Meniscal Radial Tears: A Critical Analysis Review

Because of their increased mobility, lack of resistance to hoop stresses, and decreased blood supply, radial tears of the lateral meniscus are more troublesome to heal than vertical longitudinal tears. Given the success of meniscal root repairs, radial tears of the lateral meniscal body should be given strong consideration for repair because of a more reproducible ability to heal such lesions in young, active patients. Technique options that should be considered for the less common anterior radial tears of the lateral meniscus include outside-in repair, self-capturing suture-passing devices, and orthobiologic treatments to stimulate healing. Although a variety of suture techniques, including the double horizontal mattress and horizontal butterfly patterns, have demonstrated improvements in patient outcomes, evidence is still limited with regard to the ideal suture pattern for radial tears.

Biomechanical comparison of vertical suture techniques for repairing radial meniscus tear

Purpose

The aim of this study was to (1) develop suture techniques in repairing radial meniscal tear; (2) to compare the biomechanical properties of the proposed repair techniques with the conventional double horizontal technique.

Methods

Thirty-six fresh-frozen porcine medial menisci were randomly assigned into four groups and a complete tear was made at the midline of each meniscus. The menisci were subsequently repaired using four different repair techniques: double vertical (DV), double vertical cross (DVX), hybrid composing one vertical and one horizontal stitch, and conventional double horizontal (DH) suture technique with suturing parallel to the tibia plateau. The conventional double horizontal group was the control. The repaired menisci were subjected to cyclic loading followed by the load to failure testing. Gap formation and strength were measured, stiffness was calculated, and mode of failure was recorded.

Results

Group differences in gap formation were not statistically significant at 100 cycles (p = .42), 300 cycles (p = .68), and 500 cycles (p = .70). A trend was found toward higher load to failure in DVX (276.8 N, p < .001), DV (241.5 N, p < .001), and Hybrid (237.6 N, p < .001) compared with DH (148.5 N). Stiffness was also higher in DVX (60.7 N/mm, p < .001), DV (55.3 N/mm, p < .01), and Hybrid (52.1 N/mm, p < .01), than DH group (30.5 N/mm). Tissue failure was the only failure mode observed in all specimens.

Conclusion

Our two proposed vertical suture techniques, as well as the double vertical technique, had superior biomechanical properties than the conventional technique as demonstrated by higher stiffness and higher strength.

The influence of suture materials on the biomechanical behavior of suture-meniscal specimens: a comparative study in a porcine model

Background

Repair of a meniscal tear is indicated in certain conditions. Despite extensive research on the biomechanics of various repair methods, there has been minimal investigation of whether the suture material influences the meniscal-suture construct. The purpose of this study was to compare the biomechanical properties of nine different suture materials under cyclic and load-to-failure conditions.

Methods

Ninety porcine menisci were randomly allocated to simple suture placement using either Ultrabraid®, Ultratape®, Magnum Wire®, TigerWire®, TigerTape®, LabralTape®, Orthocord®, 0 FiberWire®, or 2-0 FiberWire®. Each suture-meniscus specimen underwent cyclic loading followed by load-to-failure testing. Elongation, maximum load to failure, stiffness, and mode of failure were recorded and compared between each suture type using non-parametric testing. Mean ± standard deviation was reported and the statistical significance was p < 0.05.

Results

Elongation during cyclic loading was lowest with 2-0 FiberWire (0.95 ± 0.17 mm); this value was statistically significantly different than the results for all other sutures except 0 FiberWire® (1.09 ± 0.17 mm, p = 0.79), TigerWire® (1.09 ± 0.29 mm, p = 0.85), TigerTape® (1.39 ± 0.29 mm, p = 0.08), and LabralTape® (1.20 ± 0.33 mm, p = 0.41). The highest elongation was seen with Ultrabraid® (1.91 ± 0.34 mm); this value was statistically significantly greater than the results for all other suture materials except Orthocord® (1.59 mm ± 0.31 mm, p = 0.46) and Magnum Wire® (1.43 ± 0.25 mm, p = 0.14). Load to failure was highest for TigerTape® (287.43 ± 41.15 N), and this result was statistically significantly different than the results for all other sutures except LabralTape® (271.34 ± 48.48 N, p = 0.99) and TigerWire® (251.03 ± 25.8 N, p = 0.51). Stiffness was highest for LabralTape® (195.77 ± 49.06 N/mm), and this result was statistically significantly different than the results for all other sutures except TigerWire® (186.49 ± 19.83 N/mm, p = 0.45) and TigerTape® (173.35 ± 15.60 N/mm, p = 0.19). The majority of sutures failed by pullout (n = 46, 51%) or tearing (n = 40, 45%).

Conclusion

Suture design and material affect the biomechanical behavior of porcine meniscal-suture specimens. LabralTape®, TigerWire®, and TigerTape® demonstrated better overall combinations of low elongation, high maximum load to failure, and high stiffness.

Radial Meniscal Tears Are Best Repaired by a Modified "Cross" Tie-Grip Suture Based on a Biomechanical Comparison of 4 Repair Techniques in a Porcine Model

Background:

The tie-grip suture can fix radial tears more rigidly than simple conventional sutures. However, one shortcoming is the residual gap at the central margin of the tear. The tie-grip suture was modified to address this issue and named the “cross tie-grip suture.”

Purpose/Hypothesis:

The purpose of this study was to compare the suture stability and strength among 4 suturing techniques: the original tie-grip, cross tie-grip, and 2 conventional sutures (double horizontal and cross). It was hypothesized that the cross tie-grip suture would show the least displacement and resist the greatest maximum load.

Study Design:

Controlled laboratory study.

Methods:

A total of 40 fresh-frozen porcine knees were dissected to acquire 80 menisci; 20 menisci were tested in each suture group. A radial tear was created at the middle third of the meniscal body. Repair was performed with the following: original tie-grip, cross tie-grip, double horizontal, and cross sutures. The mechanical strength of sutured menisci was evaluated using a tensile testing machine. All menisci underwent submaximal loading and load to failure. The gap distance and ultimate failure load were compared using analysis of variance. The failure mode was recorded after load-to-failure testing.

Results:

Displacement after 500 cycles was significantly smaller in the cross tie-grip group (0.4 ± 0.3 mm) compared with the tie-grip (0.9 ± 0.6 mm), double horizontal (1.2 ± 0.7 mm), and cross suture groups (1.4 ± 0.6 mm) (P < .05). The ultimate failure load was significantly greater in the cross tie-grip (154.9 ± 29.0 N) and tie-grip (145.2 ± 39.1 N) groups compared with the double horizontal (81.2 ± 19.9 N) and cross suture groups (87.3 ± 17.7 N) (P < .05). Tissue failure was the most common mode of failure in all groups.

Conclusion:

Upon repair of radial meniscal tears, the cross tie-grip suture showed less displacement compared with that of the tie-grip, double horizontal, and cross sutures and demonstrated equivalent load to failure to that of the tie-grip suture at time zero.

Clinical Relevance:

The cross tie-grip suture provided high resistance to displacement after repair of radial tears and may be advantageous in healing for radial meniscal tears.

The rebar repair for radial meniscus tears: a biomechanical comparison of a reinforced suture repair versus parallel and cross-stitch techniques

Background

Radial meniscus tears can cause the meniscus to be completely incompetent. This serious type of meniscus tear can be difficult to repair. Techniques have been developed that juxtapose the meniscus tear edges and are able to withstand high loads. The purpose of this study was to determine the load to failure of a reinforced suture bar repair (Rebar Repair) for radial meniscus tear and compare it to the parallel suture technique and cross-stitch technique and to compare mode of failure among all three groups. The hypothesis was that the Rebar Repair will have a higher load to failure than both the parallel technique and the cross-stitch technique and that the Rebar Repair would have a lower rate of suture cutting through the meniscus.

Methods

Forty-eight menisci were tested from 24 human knee specimens, with 16 menisci in each group evenly distributed between medial and lateral menisci. Radial mid body meniscal tears were recreated and repaired with one of three inside-out techniques: the 2-parallel suture technique, 2 cross-stitch sutures, and the Rebar Repair. The specimens were cycled between 5 N to 30 N and axially loaded to failure perpendicularly across the repair site.

Results

The average load to failure of the parallel group, cross-stitch group and Rebar Repair was 85.5 N ± 22.0, 76.2 N ± 28.8 and 124.1 N ± 27.1 respectively. The Rebar Repair had a higher load to failure than the parallel group (p < 0.01) and cross-stitch group (p < 0.01). There was no difference in the load to failure between the cross-stitch and parallel group (p = 0.49). The failure mechanism was different when comparing the 3 groups (p < 0.01). The predominant mode of failure for both the parallel and cross-stitch group was suture cutout through the meniscus (88% and 94% respectively). The Rebar Repair failed due to suture rupture in 50% and suture cutout through the meniscus in 50%.

Conclusion

The Rebar Repair for radial meniscus tear has a higher load to failure and a lower rate of suture cutout through the meniscus than the parallel technique and cross-stitch technique.

Clinical relevance

Radial meniscus tears lead to decreased hoop stresses of the meniscus and effectively a non-functional meniscus. Newer techniques may have a higher load to failure leading to more successful repairs.

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

Background:

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

Purpose/Hypothesis:

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

Study Design:

Controlled laboratory study.

Methods:

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

Results:

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

Conclusion:

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

Clinical Relevance:

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

Augmented repair of radial meniscus tear with biomimetic electrospun scaffold: an in vitro mechanical analysis

Background

Large radial tears that disrupt the circumferential fibers of the meniscus are associated with reduced meniscal function and increased risk of joint degeneration. Electrospun fibrous scaffolds can mimic the topography and mechanics of fibrocartilaginous tissues and simultaneously serve as carriers of cells and growth factors, yet their incorporation into clinically relevant suture repair techniques for radial meniscus tears is unexplored. The purposes of this study were to (1) evaluate the effect of fiber orientation on the tensile properties and suture-retention strength of multilayered electrospun scaffolds and (2) determine the mechanical effects of scaffold inclusion within a surgical repair of a simulated radial meniscal tear. The experimental hypothesis was that augmentation with a multilayered scaffold would not compromise the strength of the repair.

Methods

Three multilayered electrospun scaffolds with different fiber orientations were fabricated–aligned, random, and biomimetic. The biomimetic scaffold was comprised of four layers in the following order (deep to superficial)–aligned longitudinal, aligned transverse, aligned longitudinal, and random–respectively corresponding to circumferential, radial, circumferential, and superficial collagen fibers of the native meniscus. Material properties (i.e., ultimate stress, modulus, etc.) of the scaffolds were determined in the parallel and perpendicular directions, as was suture retention strength. Complete radial tears of lateral bovine meniscus explants were repaired with a double horizontal mattress suture technique, with or without inclusion of the biomimetic scaffold sheath. Both repair groups, as well as native controls, were cyclically loaded between 5 and 20 N for 500 cycles and then loaded to failure. Clamp-to-clamp distance (i.e., residual elongation) was measured following various cycles. Ultimate load, ultimate elongation, and stiffness, were also determined. Group differences were evaluated by one-way ANOVA or Student’s t-test where appropriate.

Results

Aligned scaffolds possessed the most anisotropic mechanical properties, whereas random scaffolds showed uniform properties in the parallel and perpendicular directions. In comparison, the biomimetic scaffold possessed moduli in the parallel (68.7 ± 14.7 MPa) and perpendicular (39.4 ± 11.6 MPa) directions that respectively approximate the reported circumferential and radial tensile properties of native menisci. The ultimate suture retention load of the biomimetic scaffold in the parallel direction (7.2 ± 1.6 N) was significantly higher than all other conditions (p < 0.001). Biomimetic scaffold augmentation did not compromise mechanical properties when compared against suture repair in terms of residual elongation after 500 cycles (scaffold: 5.05 ± 0.89 mm vs. repair: 4.78 ± 1.24 mm), ultimate failure load (137.1 ± 31.0 N vs. 124.4 ± 21.4 N), ultimate elongation (12.09 ± 5.89 mm vs. 10.14 ± 4.61 mm), and stiffness (20.8 ± 3.6 vs. 18.4 ± 4.7 N/mm).

Conclusions

While multilayered scaffold sheets were successfully fabricated to mimic the ultrastructure and anisotropic tensile properties of native menisci, improvements in suture retention strength or adoption of superior surgical techniques will be needed to further enhance the mechanical strength of repairs of radial meniscal tears.

Biomechanical Comparison of Parallel and Crossed Suture Repair for Longitudinal Meniscus Tears

Background:

Longitudinal meniscus tears are commonly encountered in clinical practice. Meniscus repair devices have been previously tested and presented; however, prior studies have not evaluated repair construct designs head to head. This study compared a new-generation meniscus repair device, SpeedCinch, with a similar established device, Fast-Fix 360, and a parallel repair construct to a crossed construct. Both devices utilize self-adjusting No. 2-0 ultra–high molecular weight polyethylene (UHMWPE) and 2 polyether ether ketone (PEEK) anchors.

Hypothesis:

Crossed suture repair constructs have higher failure loads and stiffness compared with simple parallel constructs. The newer repair device would exhibit similar performance to an established device.

Study Design:

Controlled laboratory study.

Methods:

Sutures were placed in an open fashion into the body and posterior horn regions of the medial and lateral menisci in 16 cadaveric knees. Evaluation of 2 repair devices and 2 repair constructs created 4 groups: 2 parallel vertical sutures created with the Fast-Fix 360 (2PFF), 2 crossed vertical sutures created with the Fast-Fix 360 (2XFF), 2 parallel vertical sutures created with the SpeedCinch (2PSC), and 2 crossed vertical sutures created with the SpeedCinch (2XSC). After open placement of the repair construct, each meniscus was explanted and tested to failure on a uniaxial material testing machine. All data were checked for normality of distribution, and 1-way analysis of variance by ranks was chosen to evaluate for statistical significance of maximum failure load and stiffness between groups. Statistical significance was defined as P < .05.

Results:

The mean maximum failure loads ± 95% CI (range) were 89.6 ± 16.3 N (125.7-47.8 N) (2PFF), 72.1 ± 11.7 N (103.4-47.6 N) (2XFF), 71.9 ± 15.5 N (109.4-41.3 N) (2PSC), and 79.5 ± 25.4 N (119.1-30.9 N) (2XSC). Interconstruct comparison revealed no statistical difference between all 4 constructs regarding maximum failure loads (P = .49). Stiffness values were also similar, with no statistical difference on comparison (P = .28).

Conclusion:

Both devices in the current study had similar failure load and stiffness when 2 vertical or 2 crossed sutures were tested in cadaveric human menisci.

Clinical Relevance:

Simple parallel vertical sutures perform similarly to crossed suture patterns at the time of implantation.

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

BACKGROUND

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

HYPOTHESIS

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

STUDY DESIGN

Controlled laboratory study.

METHODS

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

RESULTS

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

CONCLUSION

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

CLINICAL RELEVANCE

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

Biomechanical evaluation of different suture materials for arthroscopic transtibial pull-out repair of posterior meniscus root tears

PURPOSE

To evaluate the biomechanical properties of four different suture materials for arthroscopic transtibial pull-out repair of posterior meniscus root tears, with special focus on the meniscus-suture interface.

METHODS

Forty fresh-frozen lateral porcine menisci were used. The posterior meniscus root was sutured in a standardized fashion with a simple stitch using four different suture materials: group A, No. 2 PDS™; group B, No. 2 Ethibond™; group C, No. 2 FiberWire™; and group D, 2-mm Fibertape™. Meniscus-suture constructs were subjected to cyclic loading followed by load-to-failure testing using a servo-hydraulic material testing machine.

RESULTS

During cyclic loading, group D showed a significantly higher displacement after 100, 500, and 1,000 cycles compared to group A (p < 0.001, p = 0.001, and p = 0.001), and a significantly higher displacement after 100 and 500 cycles compared to group B (p = 0.010 and p = 0.045). Group C showed a significantly higher displacement compared to group A after 100 cycles (p = 0.008). The highest maximum load was observed in group D, with significant differences compared to group A (p = 0.013). Group B showed a significantly higher stiffness compared to group A (p = 0.023), and both group C and group D showed a significantly higher stiffness compared to group A and group B (p < 0.001).

CONCLUSION

None of the evaluated suture materials provided clearly superior properties over the others during both cyclic loading and load-to-failure testing. Based on the results of this study, FiberWire™ may be the preferred suture material for transtibial pull-out repair of posterior meniscus root tears because of comparably low displacement during cyclic loading and high values for maximum load and stiffness. In the clinical setting, FiberWire™ may improve healing rates and avoid progressive extrusion of the meniscus after transtibial pull-out repair of posterior meniscus root tears.

A biomechanical evaluation of all-inside 2-stitch meniscal repair devices with matched inside-out suture repair

BACKGROUND

Many all-inside suture-based devices are currently available, including the Meniscal Cinch, FasT-Fix, Ultra FasT-Fix, RapidLoc, MaxFire, and CrossFix System. These different devices have been compared in various configurations, but to our knowledge, the Sequent meniscal repair device, which applies running sutures, has not been compared with the Ultra FasT-Fix, nor has it been compared with its suture, No. 0 Hi-Fi, using an inside-out repair technique.

PURPOSE

To assess the quality of the meniscal repair, all new devices should be compared with the gold standard: the inside-out repair. To that end, this study aims to compare the biomechanical characteristics of running sutures delivered by the Sequent meniscal repair device with 2 vertical mattress sutures applied using the Ultra FasT-Fix device and with 2 vertical mattress sutures using an inside-out repair technique with No. 0 Hi-Fi suture.

STUDY DESIGN

Controlled laboratory study.

METHODS

Paired (medial and lateral), fresh-frozen porcine menisci were randomly assigned to 1 of 3 groups: Sequent (n = 17), Ultra FasT-Fix (n = 19), and No. 0 Hi-Fi inside-out repair (n = 20). Bucket-handle tears were created in all menisci and were subjected to repair according to their grouping. Once repaired, the specimens were subjected to cyclic loading (100, 300, and 500 cycles), followed by loading to failure.

RESULTS

The Sequent and Ultra FasT-Fix device repairs and the suture repair exhibited low initial displacements. The Sequent meniscal repair device demonstrated the lowest displacement in response to cyclic loading. No. 0 Hi-Fi suture yielded the highest load to failure.

CONCLUSION

With the development of the next generation of all-inside meniscal repair devices, surgeons may use these findings to select the method best suited for their patients.

CLINICAL RELEVANCE

The Sequent meniscal repair device displays the least amount of displacement during cyclic loading but has a similar failure load to other devices.

Biomechanical comparison between suture anchor and transtibial pull-out repair for posterior medial meniscus root tears

BACKGROUND

Posterior medial meniscus root (PMMR) tears have a serious effect on knee joint biomechanics. Currently used techniques for refixation of the PMMR include the transtibial pull-out repair (TP) and suture anchor repair (SA). These techniques have not been compared biomechanically.

HYPOTHESIS

The SA technique provides superior biomechanical properties compared with the TP technique.

STUDY DESIGN

Controlled laboratory study.

METHODS

A total of 24 fresh-frozen porcine tibiae with attached intact medial menisci were used. The specimens were randomly assigned to 3 groups (8 specimens each). A standardized PMMR tear was created in 16 specimens. Refixation of the PMMR was performed by either the TP or SA technique. The native PMMR was left intact in 8 specimens. All specimens were subjected to cyclic loading followed by load-to-failure testing. Displacement after 100, 500, and 1000 cycles; maximum load to failure; stiffness; and displacement at failure were recorded.

RESULTS

Both repair techniques showed a significantly higher displacement during cyclic loading and a significantly lower maximum load and stiffness during load-to-failure testing compared with the native PMMR (P < .05). The SA technique showed a significantly lower displacement after 100, 500, and 1000 cycles (P < .001) and a significantly higher stiffness (P = .016) compared with the TP technique. Maximum load did not differ significantly between the SA and TP techniques (P = .027, Bonferroni adjustment). No significant difference between the 3 groups was observed for displacement at failure (P > .05).

CONCLUSION

The SA technique provided superior biomechanical properties compared with the TP technique. Both repair techniques did not reach the strength of the native PMMR.

CLINICAL RELEVANCE

The favorable biomechanical properties of the SA technique might be beneficial for healing of the repaired PMMR and restoration of meniscus function. Because of inferior time zero stability compared with the native PMMR, slow rehabilitation is recommended after meniscus root repair.

Outside-in continuous suturing is superior to interrupted suturing for repairing peripheral meniscus lesions: an in vitro biomechanical study using a porcine model

PURPOSE

This in vitro biomechanical study using a porcine model compared peripheral longitudinal vertical meniscus lesion (PLVML) outside-in suture repair fixation strength using either interrupted or continuous "N" configuration No. 2-0 braided polyester sutures.

METHODS

Porcine lateral menisci were randomly assigned to group 1 (continuous) or group 2 (interrupted). Standardized PLVMLs were created in each specimen. Repaired specimens were placed in a specially designed clamp and loaded into a servohydraulic device. Specimens underwent preconditioning for 10 cycles (0.1 Hz, 5 to 20 N) and 500 submaximal loading cycles (0.5 Hz, 5 to 20 N), before load-to-failure testing (12.5 mm/s). A 30-second pause after preconditioning and after 10, 100, and 500 submaximal loading cycles enabled standardized digital photographs to be taken for gapping measurement determination. The failure mode was documented.

RESULTS

Displacement and gapping during preconditioning and submaximal loading cycles did not differ between groups. Group 1 withstood a greater failure load (mean, 118.3 N; 95% confidence interval [CI], 97.2 to 139.4 N) than group 2 (mean, 63.7 N; 95% CI, 51.2 to 76.2 N) (P < .0001) and displacement during load-to-failure testing (mean, 5.3 mm; 95% CI, 4.2 to 6.5 mm) than group 2 (mean, 3.2 mm; 95% CI, 2.1 to 4.3 mm) (P = .005). Group 1 failed by suture breakage or suture pulling through tissue, whereas group 2 primarily failed by knot slippage (P < .0001).

CONCLUSIONS

Group displacement and gapping differences were not observed after 500 submaximal loading cycles. PLVMLs repaired with a continuous N configuration, however, withstood greater load at failure and greater displacement before failure than repairs that used interrupted sutures.

CLINICAL RELEVANCE

Continuous suture in an N configuration may improve PLVML repair fixation strength.

Biomechanical evaluation of different suture techniques for arthroscopic transtibial pull-out repair of posterior medial meniscus root tears

BACKGROUND

A tear of the posterior medial meniscus root (PMMR) is increasingly recognized as a serious knee joint injury. Several suture techniques for arthroscopic transtibial pull-out repair have been described; however, only limited data about the biomechanical properties of these techniques are currently available.

HYPOTHESIS

There are significant differences between the tested suture techniques, with more complex suture configurations providing superior biomechanical properties.

STUDY DESIGN

Controlled laboratory study.

METHODS

A total of 40 porcine medial menisci were randomly assigned to 1 of 4 groups (10 specimens each) according to suture technique: two simple stitches (TSS), horizontal mattress suture (HMS), modified Mason-Allen suture (MMA), and two modified loop stitches (TLS). Meniscus-suture constructs were subjected to cyclic loading followed by load-to-failure testing in a servohydraulic material testing machine.

RESULTS

During cyclic loading, the HMS and TLS groups showed a significantly higher displacement after 100, 500, and 1000 cycles compared with the TSS and MMA groups. After 1000 cycles, the highest displacement was found for the TLS group, with significant differences compared with all other groups. During load-to-failure testing, the highest maximum load and yield load were observed for the MMA group, with statistically significant differences compared with the TSS and TLS groups. With regard to stiffness, the TSS and MMA groups showed significantly higher values compared with the HMS and TLS groups.

CONCLUSION

The MMA technique provided the best biomechanical properties with regard to cyclic loading and load-to-failure testing. The TSS technique seems to be a valuable alternative. Both the HMS and TLS techniques have the disadvantage of lower stiffness and higher displacement during cyclic loading.

CLINICAL RELEVANCE

Using a MMA technique may improve healing rates and avoid progressive extrusion of the medial meniscus after transtibial pull-out repair of PMMR tears. The TSS technique may be used as an alternative that is easier to perform, but a more careful rehabilitation program is possibly necessary to avoid early failure.

Repair of peripheral vertical meniscus lesions in porcine menisci: in vitro biomechanical testing of 3 different meniscus repair devices

BACKGROUND

All-inside meniscus repair eliminates the need for an extra incision and decreases neurovascular injury risk. Biomechanical testing can help delineate the efficacy of all-inside device use.

HYPOTHESIS

There would be no group differences between 4 peripheral meniscus repair techniques and 3 different devices tested.

STUDY DESIGN

Controlled laboratory study.

METHODS

Equivalent-sized menisci with attached tibiae were randomly assigned to 1 of 4 test groups (8 specimens each), as follows: group 1, Fast-Fix using No. 0 braided polyester suture; group 2, inside-out repair using 2-0 braided polyester suture; group 3, Sequent using No. 0 ultra-high molecular weight polyethylene (UHMWPE) suture in a continuous "N" configuration; and group 4, Sequent using No. 0 UHMWPE suture in an interrupted configuration. After placement in a clamp, specimens underwent preconditioning from 5 to 20 N for 10 cycles (0.1 Hz), 500 submaximal loading cycles from 5 to 20 N (0.5 Hz), and load-to-failure testing at 12.5 mm/s. A 30-second pause after 10 preconditioning cycles and after 10, 100, and 500 submaximal loading cycles enabled digital photographs to be taken for gapping measurements. Failure mode was recorded.

RESULTS

Specimens in group 3 withstood greater failure loads than did those in groups 1 and 4 (P ≤ .027), and group 3 specimens were stiffer than those in groups 2 and 4 (P ≤ .048). Displacement during submaximal loading and load-to-failure testing did not differ between groups. Groups 1, 3, and 4 each gapped less than group 2 during submaximal cyclic loading (P ≤ .05). Groups 1 and 2 failed primarily by suture breakage (P < .0001), while groups 3 and 4 failed primarily by the suture pulling free from an implant (P < .0001).

CONCLUSION

Sequent using No. 0 UHMWPE suture in a continuous "N" configuration displayed superior load at failure compared with repairs using Fast-Fix with No. 0 braided polyester suture and displayed greater stiffness and less gapping than inside-out repair using 2-0 braided polyester suture. The suture pulling free from an implant was the primary failure mode for Sequent using No. 0 UHMWPE suture regardless of whether a continuous "N" or an interrupted configuration was used. Study groups that used No. 0 UHMWPE sutures (groups 3 and 4) had more specimens fail by the suture pulling free from an implant. Compared with the weaker braided polyester suture in the inside-out and Fast-Fix groups, the No. 0 UHMWPE suture used in the Sequent groups likely influenced study results, as this suture has stronger material properties. However, the continuous "N" configuration likely also improved the performance of the Sequent with No. 0 UHMWPE suture, as failure load was significantly less with an interrupted configuration.

CLINICAL RELEVANCE

All-inside meniscus repair with continuous suture function may translate into improved patient outcomes.