Biomechanical evaluation of meniscal repair systems: a comparison of the Meniscal Viper Repair System, the vertical mattress FasT-Fix Device, and vertical mattress ethibond sutures

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.

Biomechanical Performance of Transtibial Pull-Out Posterior Horn Medial Meniscus Root Repair Is Improved With Knotless Adjustable Suture Anchor-Based Fixation

Background

While posterior medial meniscus root (PMMR) techniques have evolved, there remains a need to both optimize repair strength and improve resistance to cyclic loading.

Hypothesis

Adjustable tensioning would lead to higher initial repair strength and reduce displacement with cyclic loading compared with previously described transtibial pull-out repair (TPOR) fixation techniques.

Study Design

Controlled laboratory study.

Methods

A total of 56 porcine medial menisci were used. Eight intact specimens served as a control for the native meniscus. For the others, PMMR tears were created and repaired with 6 different TPOR techniques (8 in each group). Fixed PMMR repairs were executed using 4 different suture techniques (two No. 2 cinch sutures, two cinch tapes, two No. 2 simple sutures, and two No. 2 sutures in a Mason-Allen configuration) all tied over a cortical button. Adjustable PMMR repairs using Mason-Allen sutures were fixed with an adjustable soft tissue anchor fixation tensioned at either 80 N or 120 N. The initial force, stiffness, and relief displacement of the repairs were measured after fixation. Repair constructs were then cyclically loaded, with cyclic displacement and stiffness measured after 1000 cycles. Finally, the specimens were pulled to failure.

Results

The PMMR repaired with the 2 cinch sutures fixed technique afforded the lowest (P < .001) initial repair load, stiffness, and relief displacement. The adjustable PMMR repairs achieved a higher initial repair load (P < .001) and relief displacement (P < .001) than all fixed repairs. The 2 cinch sutures fixed technique showed an overall higher cyclic displacement (P < .028) and was completely loose compared with the native meniscus functional zone. Repairs with adjustable intratunnel fixation showed displacement with cyclic loading similar to the native meniscus. With cyclic loading, the Mason-Allen adjustable repair with 120 N of tension showed less displacement (P < .016) than all fixed repairs and a stiffness comparable to the fixed Mason-Allen repair. The fixed Mason-Allen technique demonstrated a higher ultimate load (P < .007) than the adjustable Mason-Allen techniques. All repairs were less stiff, with lower ultimate failure loads, than the native meniscus root attachment (P < .0001).

Conclusion

Adjustable TPOR led to considerably higher initial repair load and relief displacement than other conventional fixed repairs and restricted cyclic displacement to match the native meniscus function. However, the ultimate failure load of the adjustable devices was lower than that of a Mason-Allen construct tied over a cortical button. All repair techniques had a significantly lower load to failure than the native meniscus root.

Clinical Relevance

Knotless adjustable PMMR repair based on soft anchor fixation results in higher tissue compression and less displacement, but the overall clinical significance on healing rates remains unclear.

Continuous Vertical Inside-Out Versus Traditional Vertical Inside-Out Meniscal Repair: A Biomechanical Comparison

Background

Biomechanical assessment of meniscal repairs is essential for evaluating different meniscal suturing methods and techniques. The continuous meniscal suture technique is a newer method of meniscal repair that may have biomechanical differences compared with traditional techniques.

Purpose

To evaluate the displacement, stiffness after cyclical loading, and load to failure for a continuous vertical inside-out meniscal suture versus a traditional vertical inside-out meniscal suture in a porcine medial meniscus.

Study Design

Controlled laboratory study.

Methods

A total of 28 porcine knees were acquired and divided into 2 test groups of 14 medial meniscus each. A 2.0-cm longitudinal red-white zone cut was made in the body of the medial meniscus for each knee. The continuous suture (CS) group received 4 vertical stitches performed with a continuous vertical meniscal suture technique, and the inside-out suture (IO) group received a traditional vertical suture with 4 stitches. Two traction tapes were passed between the sutures and positioned in the biomechanical testing fixture device. Each specimen underwent load-to-failure testing at 5 mm/s, and displacement, system stiffness, and maximum load to failure were compared between the groups.

Results

The displacement after the cyclic test was 0.53 ± 0.12 and 0.48 ± 0.07 mm for the CS and IO groups, respectively. There was no significant difference between the groups (P = .2792). The stiffness at the ultimate load testing was 36.3 ± 1.9 and 35.3 ± 2.4 N/mm for groups CS and IO, respectively, with no significant difference between the groups (P = .2557). In the load-to-failure test, the ultimate load was 218.2 ± 63.9 and 238.3 ± 71.3 N in the CS and IO groups, respectively, with no significant group differences (P = .3062).

Conclusion

A continuous vertical meniscal suture created a configuration for treating longitudinal meniscal lesions that was beneficial and biomechanically similar to a traditional vertical suture technique.

Clinical Relevance

The study findings indicate that use of the continuous vertical inside-out meniscal suture technique is a possible therapeutic option.

Primary Fixation and Cyclic Performance of Single-Stitch All-Inside and Inside-Out Meniscal Devices for Repairing Vertical Longitudinal Meniscal Tears

BACKGROUND

Primary device fixation and the resistance against gap formation during repetitive loading influence the quality of meniscal repair. There are limited biomechanical data comparing primary tensioning and cyclic behavior of all-inside versus inside-out repair.

HYPOTHESIS

All-inside devices provide higher initial load on the meniscal repair than inside-out fixation, and stiffer constructs show higher resistance against gap formation during cyclic loading.

STUDY DESIGN

Controlled laboratory study.

METHODS

In total, 60 longitudinal bucket-handle tears in human cadaveric menisci were created and repaired with a single stitch and randomly assigned to 4 all-inside groups (TrueSpan, FastFix 360, Stryker AIR, FiberStich) and 2 inside-out groups (suture repair [IO-S], suture tape [IO-ST]). Residual load after repair tensioning (50 N) and relief displacement were measured. Constructs underwent cyclic loading between 2 and 20 N over 500 cycles (0.75 Hz) with cyclic stiffness, gap formation, and final peak elongation measured. Ultimate load and stiffness were analyzed during pull to failure (3.15 mm/s).

RESULTS

All-inside repair demonstrated significantly higher primary fixation strength than inside-out repair. The significantly highest load (mean ± SD; 20.1 ± 0.9 N; P < .037) and relief displacement (-2.40 ± 0.32 mm; P < .03) were for the knotless soft anchoring FiberStich group. The lowest initial load (9.0 ± 1.5 N; P < .001) and relief displacement (-1.39 ± 0.26 mm; P < .045) were for the IO-S repair group. The final gap formation (500th cycle) of FiberStich (0.75 ± 0.37 mm; P < .02) was significantly smaller than others and that of the IO-S (1.47 ± 0.33 mm; P < .045) significantly larger. The construct stiffness of the FiberStich and IO-ST groups was significantly greater at the end of cyclic testing (16.7 ± 0.80 and 15.5 ± 1.42 N/mm; P < .042, respectively) and ultimate failure testing (23.4 ± 3.6 and 20.6 ± 2.3 N/mm; P < .005). The FastFix 360 (86.4 ± 4.8 N) and Stryker AIR (84.4 ± 4.6 N) groups failed at a significantly lower load than the IO-S group (P < .02) with loss of anchor support. The FiberStich (146.8 ± 23.4 N), TrueSpan (142.0 ± 17.8 N), and IO-ST (139.4 ± 7.3 N) groups failed at significantly higher loads (P < .02) due to suture tearing.

CONCLUSION

Overall, primary fixation strength of inside-out meniscal repair was significantly lower than all-inside repair in this cadaveric tissue model. Although absolute differences among groups were small, meniscal repairs with higher construct stiffness (IO-ST, FiberStich) demonstrated increased resistance against gap formation and failure load.

CLINICAL RELEVANCE

Knotless single-stitch all-inside meniscal repair with a soft anchor resulted in less gapping, but the overall clinical significance on healing rates remains unclear.

Six-Month Outcomes of Clinically Relevant Meniscal Injury in a Large-Animal Model

BACKGROUND

The corrective procedures for meniscal injury are dependent on tear type, severity, and location. Vertical longitudinal tears are common in young and active individuals, but their natural progression and impact on osteoarthritis (OA) development are not known. Root tears are challenging and they often indicate poor outcomes, although the timing and mechanisms of initiation of joint dysfunction are poorly understood, particularly in large-animal and human models.

PURPOSE/HYPOTHESIS

In this study, vertical longitudinal and root tears were made in a large-animal model to determine the progression of joint-wide dysfunction. We hypothesized that OA onset and progression would depend on the extent of injury-based load disruption in the tissue, such that root tears would cause earlier and more severe changes to the joint.

STUDY DESIGN

Controlled laboratory study.

METHODS

Sham surgeries and procedures to create either vertical longitudinal or root tears were performed in juvenile Yucatan mini pigs through randomized and bilateral arthroscopic procedures. Animals were sacrificed at 1, 3, or 6 months after injury and assessed at the joint and tissue level for evidence of OA. Functional measures of joint load transfer, cartilage indentation mechanics, and meniscal tensile properties were performed, as well as histological evaluation of the cartilage, meniscus, and synovium.

RESULTS

Outcomes suggested a progressive and sustained degeneration of the knee joint and meniscus after root tear, as evidenced by histological analysis of the cartilage and meniscus. This occurred in spite of spontaneous reattachment of the root, suggesting that this reattachment did not fully restore the function of the native attachment. In contrast, the vertical longitudinal tear did not cause significant changes to the joint, with only mild differences compared with sham surgery at the 6-month time point.

CONCLUSION

Given that the root tear, which severs circumferential connectivity and load transfer, caused more intense OA compared with the circumferentially stable vertical longitudinal tear, our findings suggest that without timely and mechanically competent fixation, root tears may cause irreversible joint damage.

CLINICAL RELEVANCE

More generally, this new model can serve as a test bed for experimental surgical, scaffold-based, and small molecule-driven interventions after injury to prevent OA progression.

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.

Increased Construct Stiffness With Meniscal Repair Sutures and Devices Increases the Risk of Cheese-Wiring During Biomechanical Load-to-Failure Testing

Background:

Cheese-wiring, the suture that cuts through the meniscus, is a well-known issue in meniscal repair. So far, contributing factors are neither fully understood nor sufficiently studied.

Hypothesis/Purpose:

To investigate whether the construct stiffness of repair sutures and devices correlates with suture cut-through (cheese-wiring) during load-to-failure testing.

Study Design:

Controlled laboratory study.

Methods:

In 131 porcine menisci, longitudinal bucket-handle tears were repaired using either inside-out sutures (n = 66; No. 0 Ultrabraid, 2-0 Orthocord, 2-0 FiberWire, and 2-0 Ethibond) or all-inside devices (n = 65; FastFix360, Omnispan, and Meniscal Cinch). After cyclic loading, load-to-failure testing was performed. The mode of failure and construct stiffness were recorded. A receiver operating characteristic curve analysis was performed to define the optimal stiffness threshold for predicting meniscal repair failure by cheese-wiring. The 2-tailed t test and analysis of variance were used to test significance.

Results:

Loss of suture fixation was the most common mode of failure in all specimens (58%), except for the Omnispan, which failed most commonly because of anchor pull-through. The Omnispan demonstrated the highest construct stiffness (30.8 ± 3.5 N/mm), whereas the Meniscal Cinch (18.0 ± 8.8 N/mm) and Ethibond (19.4 ± 7.8 N/mm) demonstrated the lowest construct stiffness. The Omnispan showed significantly higher stiffness compared with the Meniscal Cinch (P < .001) and Ethibond (P = .02), whereas the stiffness of the Meniscal Cinch was significantly lower compared with that of the FiberWire (P = .01), Ultrabraid (P = .04), and FastFix360 (P = .03). While meniscal repair with a high construct stiffness more often failed by cheese-wiring, meniscal repair with a lower stiffness failed by loss of suture fixation, knot slippage, or anchor pull-through. Meniscal repair with a stiffness >26.5 N/mm had a 3.6 times higher risk of failure due to cheese-wiring during load-to-failure testing (95% CI, 1.4-8.2; P < .0001).

Conclusion:

Meniscal repair using inside-out sutures and all-inside devices with a higher construct stiffness (>26.5 N/mm) was more likely to fail through suture cut-through (cheese-wiring) than that with a lower stiffness (≤26.5 N/mm).

Clinical Relevance:

This is the first study investigating the impact of construct stiffness on meniscal repair failure by suture cut-through (cheese-wiring).

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.

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.

Biomechanical Comparison of Suture Techniques in Radial Meniscal Tears Using Gap Configuration Analysis

Vertical, horizontal, and cross sutures have not been compared simultaneously in double suture fashion for the repair of radial meniscal tears. This study compared suture strength among these 3 techniques using gap configuration analysis. Biomechanical testing was performed on 60 matched and paired porcine menisci that were repaired with 2 stitches of vertical, horizontal, and cross sutures. The specimens were cyclically loaded 500 times at 5 to 30 N, and central, peripheral, and total gap distance were measured. After completing cyclic load testing, the specimens were loaded to failure. Double vertical sutures demonstrated significantly lower total and central gap displacement than cross and double horizontal sutures (P<.05). However, there was no significant difference in peripheral gap formation within each group (P=.53). Ultimate failure load and stiffness were significantly greater for double vertical sutures (146.3 N) than for cross (113.8 N) and double horizontal sutures (107.2 N) (P<.05). Stiffness also was significantly increased for double vertical sutures (14.6 N/mm) compared with cross (11.3 N/mm) and double horizontal sutures (10.7 N/mm) (P<.05). There was no significant difference in biomechanical properties between cross and double horizontal sutures. Double vertical sutures showed superior mechanical properties compared with cross and double horizontal sutures in repair of radial meniscal tears, especially in the central zone. These biomechanical properties should be considered when determining appropriate rehabilitation protocols for each suture technique. [Orthopedics. 2019; 42(5):e443-e448.].

Comparison of Tibiofemoral Contact Mechanics After Various Transtibial and All-Inside Fixation Techniques for Medial Meniscus Posterior Root Radial Tears in a Porcine Model

PURPOSE

To compare tibiofemoral contact mechanics after fixation for medial meniscus posterior root radial tears (MMPRTs).

METHODS

Seven fresh knees from mature pigs were used. Each knee was tested under 5 conditions: normal knee, MMPRT, pullout fixation with simple sutures, fixation with modified Mason-Allen sutures, and all-inside fixation using Fastfix 360. The peak contact pressure and contact surface area were evaluated using a capacitive sensor positioned between the meniscus and tibial plateau, under a 1,000-N compression force, at different flexion angles (0°, 30°, 60°, and 90°).

RESULTS

The peak contact pressure was significantly higher in MMPRTs than in normal knees (P = .018). Although the peak contact pressure decreased significantly after fixation at all flexion angles (P = .031), it never recovered to the values noted in the normal meniscus. No difference was observed among fixation groups (P = .054). The contact surface area was significantly lower in MMPRTs than in the normal meniscus (P = .018) and increased significantly after fixation at all flexion angles (P = .018) but did not recover to within normal limits. For all flexion angles except 60°, the contact surface area was significantly higher for fixation with Mason-Allen sutures than for fixation with simple sutures or all-inside fixation (P = .027). At 90° of flexion, the contact surface area was significantly better for fixation with simple sutures than for all-inside fixation (P = .031).

CONCLUSIONS

The peak contact pressure and contact surface area improved significantly after fixation, regardless of the fixation method, but did not recover to the levels noted in the normal meniscus after any type of fixation. Among the fixation methods evaluated in this time 0 study, fixation using modified Mason-Allen sutures provided a superior contact surface area compared with that noted after fixation using simple sutures or all-inside fixation, except at 60° of flexion. However, this study had insufficient power to accurately detect the differences between the outcomes of various fixation methods.

CLINICAL RELEVANCE

Our results in a porcine model suggest that fixation can restore tibiofemoral contact mechanics in MMPRT and that fixation with a locking mechanism leads to superior biomechanical properties.

Novel flat and wide meniscal repair material improves the ultimate load of knot breakage in a porcine trans-capsular meniscal repair model

Background

In the meniscal repair procedures, a high ultimate load capacity and low cyclic creep at the repair site are favorable and lead to good biological incorporation of the tear site after surgery. Previous biomechanical tensile tests of the meniscal sutures have identified the suture knot as the weakest point. We hypothesized that the strength of a suture knot depends on the suture shape, and therefore, we compared three differently shaped suture materials composed of the same material and quantity per length. The purpose of this study was to determine whether a novel flat and wide repair material (FWRM), which consists of braided multi-threads that are cross-sectionally flat and wide, improves the ultimate load of knot breakage in a biomechanical experiment using a porcine trans-capsular meniscal repair model.

Methods

Eighteen fresh-frozen porcine knees (n = 6 in each group) were used. A longitudinal tear in the middle segment of the medial meniscus was created and repaired with a trans-capsular inside-out method using the following suture materials: No. 2–0 braided polyester conventional suture, hollow suture, and FWRM. After the separation of the inner segment of the meniscus with leaving, the suture stability of the repaired menisci was biomechanically analyzed with a video camera system for widening after a cyclic load between 5 and 20 N was applied 300 times. Ultimate failure load and stiffness at 5 mm/ min were also analyzed.

Results

We found no significant difference in suture widening after cyclic load tests [conventional suture, mean 0.51 mm (S.D. 0.39 mm); hollow suture, mean 0.23 mm (S.D. 0.11 mm); and FWRM, mean 0.54 mm (S.D. 0.08 mm)]. The failure mode in all specimens was knot breakage. Compared with those of the other groups, the ultimate failure load of FWRM was statistically significantly higher in the load-to-failure tests (conventional suture, mean 58.8 N [S.D. 8.25 N]; hollow suture, mean 79.4 N [S.D. 10.2 N]; and FWRM, mean 97.4 N [S.D. 3.65 N]; p < 0.05).

Conclusion

FWRM improves the ultimate load of knot breakage without altering stability. This material may contribute to safe and stable meniscus repair.

Biomechanical testing of transcapsular meniscal repair

Background

All of previous biomechanical studies on meniscal repair have examined the meniscus itself without synovial membrane and capsule, although in the clinical setting, the meniscal repair is generally performed including capsule. Therefore, biomechanical properties of transcapsular meniscal repair are unclear. Thus, this study aimed to clarify the biomechanical properties of transcapsular meniscal repair.

Methods

In 70 porcine femur–medial meniscus–tibia complexes with capsules, longitudinal meniscal tears were repaired using different suture techniques (inside-out or all-inside technique), suture methods (vertical or horizontal methods), and numbers of sutures (single or double). A cyclic loading test between 5 and 20 N for 300 cycles was performed followed by a load-to-failure test.

Results

Tears repaired by the all-inside technique presented significantly larger widening (0.88 ± 0.38 mm) than those by the inside-out technique (0.51 ± 0.39 mm) during the cyclic loading test (P = 0.035). The horizontal suture presented significantly lower ultimate failure load (62.5 ± 15.5 N) in the all-inside technique than in the vertical suture (79.7 ± 13.0 N; P = 0.018). The stacked suture had a significantly higher failure load (104.6 ± 12.5 N) than the parallel suture (83.3 ± 12.6 N; P = 0.001). Furthermore, the double suture presented significantly higher failure loads (83.3 ± 12.6 N and 104.6 ± 20.4 N) than the single suture with both inside-out (58.8 ± 8.3 N; P = 0.001) and all-inside (79.7 ± 13.0 N; P = 0.022) techniques.

Conclusions

Upon comparison of the suture techniques, the inside-out technique provided a more stable fixation at the repair site than the all-inside technique during the cyclic test. Among the suture methods, the vertical suture had more desirable biomechanical properties than the horizontal suture as demonstrated by smaller widening during the cyclic test and the larger load to failure. The stacked suture created a stronger fixation than the parallel suture. In terms of the number of sutures, the double suture had superior biomechanical properties compared with the single suture.

Advances in combining gene therapy with cell and tissue engineering-based approaches to enhance healing of the meniscus

Meniscal lesions are common problems in orthopaedic surgery and sports medicine, and injury or loss of the meniscus accelerates the onset of knee osteoarthritis (OA). Despite a variety of therapeutic options in the clinics, there is a critical need for improved treatments to enhance meniscal repair. In this regard, combining gene-, cell-, and tissue engineering-based approaches is an attractive strategy to generate novel, effective therapies to treat meniscal lesions. In the present work, we provide an overview of the tools currently available to improve meniscal repair and discuss the progress and remaining challenges for potential future translation in patients.

Biomechanical evaluation of an all-inside suture-based device for repairing longitudinal meniscal tears

PURPOSE

A device for all-inside suture-based meniscal repairs has been introduced (NovoStitch; Ceterix, Menlo Park, CA) that passes the suture vertically through the meniscus, thereby encircling the tear, and does not require an additional incision or extra-capsular anchors. Our aim was to compare this all-inside suture-based repair with an inside-out suture repair and an all-inside anchor-based repair (FasT-Fix 360°; Smith & Nephew, Andover, MA).

METHODS

Longitudinal tears were created in 36 fresh-frozen porcine menisci. Repairs were performed using an all-inside suture-based meniscal repair device, an all-inside anchor-based repair, and an inside-out suture repair. They were tested with cyclic loading and load-to-failure testing. The displacement, response to cyclic loading (100, 300, and 500 cycles), and mode of failure were recorded. The stiffness of the constructs was calculated as well.

RESULTS

The all-inside suture-based repairs and the inside-out repairs showed significantly higher loads to failure than the all-inside anchor-based repairs. The stiffness values for the 3 repairs were not different. There were no differences in initial displacement. After 100, 300, and 500 cycles, the inside-out repair had higher gap formation (displacement) than the other 2 groups. Suture failure was the predominant mode of failure across all repair techniques.

CONCLUSIONS

The all-inside suture-based repairs and inside-out repairs did not exhibit different load-to-failure values. In addition, the all-inside suture-based repairs and the all-inside anchor-based repairs did not exhibit different displacement values during cyclic loading.

CLINICAL RELEVANCE

When addressing a longitudinal meniscal tear, surgeons should consider biomechanical data of various repair devices and techniques in their decision-making process to maximize the mechanical strength and healing probability of the repair.

Analysis of a new all-inside versus inside-out technique for repairing radial meniscal tears

PURPOSE

The purpose of this study was to compare gap formation, strength, and stiffness of repaired radial tears of the meniscus treated using a new all-inside technique versus a traditional inside-out suture technique.

METHODS

Radial tears were created in 36 fresh-frozen porcine menisci. Repairs were performed using a novel all-inside suture-based meniscal repair device or an inside-out technique. The repairs were tested for cyclic loading and load to failure. The displacement, response to cyclic loading (100, 300, and 500 cycles), and mode of failure were recorded, and the construct's stiffness was calculated.

RESULTS

The all-inside repairs using the novel device resulted in a significantly lower displacement (gap formation) after 100, 300, and 500 cycles (P = .002, P = .001, and P = .001, respectively). The ultimate load to failure was significantly greater for the all-inside repairs (111.61 N v 95.01 N; P = .03). The all-inside repairs showed greater stiffness (14.53 N/mm v 11.19 N/mm; P = .02). The all-inside repairs failed most often by suture breakage (suture failure). The inside-out repairs failed most commonly when the suture pulled through the tissue (tissue failure) (P < .001).

CONCLUSIONS

For repair of radial tears of the meniscus, the vertical suture configuration created by the all-inside technique resulted in lower displacement, higher load to failure, and greater stiffness compared with the horizontal inside-out technique.

CLINICAL RELEVANCE

In a porcine specimen meniscus repair model, the biomechanical properties of a vertical all-inside technique were superior to that of a horizontal inside-out technique. Future studies of biomechanical and clinical outcomes in human meniscal repairs with this device are warranted to explore whether this repair method is valuable to clinical practice and patient outcomes.

What is the best way to fix a polyurethane meniscal scaffold? A biomechanical evaluation of different fixation modes

PURPOSE

Ingrowth of meniscal tissue into a meniscal scaffold can be optimized by securely fixing the scaffold into the meniscal remnants. The purpose of this research was to test and compare commonly used suture types and suture materials to fix a meniscal scaffold.

METHODS

Forty fresh porcine menisci were used. All tests used the same polyurethane-based scaffold. The load to failure of horizontal, vertical and diagonal sutures with PDS 0 and with Ethibond 0, and diagonal sutures with Ultra Fast-Fix(®) and Sequent(®) to fix a meniscal scaffold were tested. Five tests were conducted for each configuration.

RESULTS

All constructs failed in the scaffold at a mean pullout force of 50.6 N (SD 12.7). Inferior results were noted for vertical sutures (40.1 N, SD 6.3) compared to horizontal (49.8 N, SD 5.5, p = 0.0007) and diagonal (51.7 N, SD 15.6, p = 0.024) sutures and for Ethibond 0 (41.4 N, SD 6.2) compared to PDS 0 (51.3 N, SD 12.9, p = 0.001). When comparing the diagonal suture placements, only Ethibond 0 (42.9 N, SD 5.4) showed significantly inferior results compared to PDS 0 (60.1 N, SD 16.9, p = 0.03), Ultra Fast-Fix(®) (60.1 N, SD 9.3, p = 0.004) and Sequent(®) (65.8 N, SD 4.4, p < 0.0001).

CONCLUSIONS

The most common failure mode when fixing a polyurethane-based meniscal scaffold is suture pull-through of the scaffold in the distraction mode. This happens at a rather low pullout force and might preclude the use of this scaffold clinically. Vertical sutures and Ethibond 0 multifilament braided sutures fail at lower forces, and the tested commercial devices show promising results.

The concept of three-dimensional hold of both circumferential and radial collagen fibres of the meniscus

Collagen fibres of the meniscus arrange into two main orientations: circumferential fibres parallel to the long axis of the meniscus and radial fibres perpendicular to the long axis of the meniscus. Meniscal sutures are placed either in vertical or in horizontal orientations. Vertical sutures better hold circumferential fibres because it encircles them like a rope holding a bunch of tree branches. In the same manner, horizontal sutures better hold radial fibres. The "Simplified Cruciate Suture" consists of two vertical oblique sutures. Placing two vertical sutures in an oblique orientation captures greater meniscal tissue volume, holds and grasps both circumferential and radial collagen fibres of the meniscus into a three-dimensional plane with eventual high fixation strength of the repaired meniscal tear. Simplified cruciate suture is indicated for the repair of long bucket handle tears where it is placed in the middle of the tear like an anchor, and additional vertical and horizontal sutures are placed anterior and posterior to it as needed. Level of evidence V.

Meta-analysis on biomechanical properties of meniscus repairs: are devices better than sutures?

PURPOSE

Meniscal repair devices have been extensively tested during the past decades as reported in the literature. Reviewing the different meniscal repair devices and sutures with their respective biomechanical properties.

METHODS

For this meta-analysis, we conducted a systematic online search using PubMed, EMBASE, CCTR, and CINAHL using the search terms Meniscus OR Meniscal AND Biomechanics AND Repair). Load-to-failure (LtF), stiffness, and cyclic outcome measures were extracted independently and in duplicate. The systematic search revealed 841 manuscripts in total. After exclusion of duplicates and irrelevant publications, 41 studies remained for final analysis. The studies were published in English and German from 1995 to 2013. Due to differing cyclic force protocols, cyclic outcomes had to be excluded.

RESULTS

Overall, sutures had a higher LtF [suture: 87.7 ± 0.3 N (weighted mean ± standard error), device: 56.3 ± 0.1 N] and stiffness (suture: 8.9 ± 0.04 N/mm, device: 8.6 ± 0.04 N/mm) than devices, both p < 0.05. In LfT testing, PDS 0 Vertical (145.0 ± 8.1 N), OrthoCord 2-0 (143.6 ± 11.3 N), and Ethibond No 0 Vertical (133.4 ± 7.7 N) were the strongest sutures and Meniscal Viper (140.9 ± 5.1 N), MaxFire Vertical (136.2 ± 11.3 N), and FasT-Fix Vertical (115.2 ± 1.6 N) were the strongest devices. Second-generation devices were significantly stronger and stiffer than first-generation devices (p < 0.001).

CLINICAL RELEVANCE

Suture repair remains the gold standard with a vertically oriented suture configuration showing superior LtF values compared to a horizontal configuration. Nevertheless, some meniscal repair devices have similar biomechanical properties to suture repairs. Both suture repairs and devices have a place in meniscal restoration.

LEVEL OF EVIDENCE

None, meta-analysis of controlled laboratory studies.

Short- to mid-term results of arthroscopic meniscal repair of long vertical longitudinal tears using combined cruciate and horizontal suture techniques: a retrospective study

INTRODUCTION

The purpose was to evaluate the clinical results of arthroscopic meniscal repair of long vertical longitudinal tears using combined cruciate and horizontal suture techniques.

METHODS

Single surgeon retrospective case series study. A total of 38 patients having long vertical longitudinal tears were operated using combined cruciate and horizontal suture techniques. Two patients had to undergo a meniscectomy procedure within the 1st year postoperative and those were considered failure cases; 32 patients were available for follow-up evaluation (average 4.6 years) and six were lost including the two failures. Objective IKDC, modified Lysholm knee score, SF-36 score, VAS for patients' satisfaction and VAS for pain were used for follow-up evaluation. Kellgren and Lawrence (K/L) classification of osteoarthritis was also used.

RESULTS

Successful rate was 94.1% (32 patients), while failure was 5.9% (2 patients). Objective IKDC score revealed that 27 patients had grade "A" and 5 had grade "B," while no single patient had neither grade "C" nor "D." The average modified Lysholm score was 91.3. Average SF-36 score was 88.4. The average VAS for operation satisfaction was eight. Average VAS for pain was 1.5. Preoperatively, 30 patients were classified as normal K/L classification, while two patients were K/L classification grade "1." At the time of the follow-up, 24 patients were classified as normal K/L classification, six were grade "1," two were grade "2," and thus, six had osteoarthritis progression.

CONCLUSION

Arthroscopic meniscal repair of long vertical longitudinal tears using combined cruciate and horizontal suture techniques is a safe surgical procedure with good clinical outcome.

LEVEL OF EVIDENCE

Level IV.

The influence of suture material on the strength of horizontal mattress suture configuration for meniscus repair

PURPOSE

Comparison of the mechanical characteristics of meniscal repair fixation using horizontal sutures and six different sutures under submaximal cyclic and load to failure test conditions may aid physicians in selecting a suture type.

METHODS

A 2-cm long anteroposterior vertical longitudinal incision was created in six groups of bovine medial menisci. Lesions were repaired using a No. 2 suture either composed of polyester or polyester and ultra high-molecular weight polyethylene (UHMWPE), or UHMWPE and polydioxanone or pure UHMWPE. Endpoints included ultimate failure load (N), pull-out stiffness (N/mm), pull-out displacement (mm), cyclic displacement (mm) after 100cycles, after 500cycles, and mode of failure.

RESULTS

Polyester suture had lower ultimate load than all groups except the suture composed of polyester and UHMWPE (P<.05). Pure UHMWPE suture had higher ultimate failure load than sutures composed of either polyester or polyester plus UHMWPE (P<.05). Predominant failure mode was suture cutting through the meniscus for the groups except for polyester suture which failed by suture rupture.

CONCLUSION

Under cyclic loading conditions in bovine meniscus, braided polyester suture fixation provided lower initial fixation strength than fixation with various high strength sutures composed of pure UHMWPE or a combination of absorbable monofilament polydioxanone and UHMWPE, except for combination of polyester and UHMWPE sutures.

CLINICAL RELEVANCE

Present study does not support the usage of the braided polyester sutures instead of high strength sutures composed either partially or totally of ultra-high molecular weight polyethylene for the horizontal suture configuration of meniscus repair.

Stem cell-based tissue-engineering for treatment of meniscal tears in the avascular zone

Meniscal tears in the avascular zone have a poor self-healing potential, however partial meniscectomy predisposes the knee for early osteoarthritis. Tissue engineering with mesenchymal stem cells and a hyaluronan collagen based scaffold is a promising approach to repair meniscal tears in the avascular zone. 4 mm longitudinal meniscal tears in the avascular zone of lateral menisci of New Zealand White Rabbits were performed. The defect was left empty, sutured with a 5-0 suture or filled with a hyaluronan/collagen composite matrix without cells, with platelet rich plasma or with autologous mesenchymal stem cells. Matrices with stem cells were in part precultured in chondrogenic medium for 14 days prior to the implantation. Menisci were harvested at 6 and 12 weeks. The developed repair tissue was analyzed macroscopically, histologically and biomechanically. Untreated defects, defects treated with suture alone, with cell-free or with platelet rich plasma seeded implants showed a muted fibrous healing response. The implantation of stem cell-matrix constructs initiated fibrocartilage-like repair tissue, with better integration and biomechanical properties in the precultured stem cell-matrix group. A hyaluronan-collagen based composite scaffold seeded with mesenchymal stem cells is more effective in the repair avascular meniscal tear with stable meniscus-like tissue and to restore the native meniscus.

Biomechanical testing of suture-based meniscal repair devices containing ultrahigh-molecular-weight polyethylene suture: update 2011

PURPOSE

To evaluate the biomechanical characteristics of recently introduced ultrahigh-molecular-weight polyethylene suture-based, self-adjusting meniscal repair devices.

METHODS

Updating a prior study published in 2009, we made vertical longitudinal cuts 3 mm from the periphery in fresh-frozen adult human menisci to simulate a bucket-handle meniscus tear. Each tear was then repaired by a single repair technique in 10 meniscus specimens. Group 1 menisci were repaired with a vertical mattress suture of No. 2-0 Ethibond (Ethicon, Somerville, NJ). Group 2 menisci were repaired with a vertical mattress suture of No. 2-0 OrthoCord (DePuy Mitek, Raynham, MA). Group 3 menisci were repaired with a single OmniSpan device with No. 2-0 OrthoCord suture (DePuy Mitek). Group 4 menisci were repaired with a single Meniscal Cinch device with No. 2-0 FiberWire suture (Arthrex, Naples, FL). Group 5 menisci were repaired with a single MaxFire device inserted with the MarXmen gun (Biomet Sports Medicine, Warsaw, IN). Group 6 menisci were repaired with a Sequent device with No. 0 Hi-Fi suture (ConMed Linvatec, Largo, FL) in a "V" suture configuration. Group 7 menisci were repaired with a single FasT-Fix 360 device (Smith & Nephew Endoscopy, Andover, MA). By use of a mechanical testing machine, all samples were preloaded at 5 N and cycled 200 times between 5 and 50 N. Those specimens that survived were destructively tested at 5 mm/min. Endpoints included maximum load, displacement, stiffness, and failure mode.

RESULTS

Mean failure loads were as follows: Ethibond suture, 73 N; OrthoCord suture, 88 N; OmniSpan, 88 N; Cinch, 71 N; MarXmen/MaxFire, 54 N; Sequent, 66 N; and FasT-Fix 360, 60 N. Ethibond was stronger than MarXmen/MaxFire. The mean displacement after 100 cycles was as follows: Ethibond, 2.58 mm; OrthoCord, 2.75 mm; OmniSpan, 2.51 mm; Cinch, 2.65 mm; MarXmen/MaxFire, 3.67 mm; Sequent, 3.35 mm; and FasT-Fix 360, 1.13 mm. The MarXmen/MaxFire showed greater 100-cycle displacement than Ethibond and FasT-Fix 360. No difference in stiffness existed for these devices, and failure mode varied without specific trends.

CONCLUSIONS

The biomechanical properties of meniscal repairs using the OmniSpan, Cinch, Sequent, and FasT-Fix 360 devices are equivalent to suture repair techniques. However, the MarXmen/MaxFire meniscal repair device showed significantly lower failure loads and survived less cyclic loading in the human cadaveric meniscus than other tested repairs.

CLINICAL RELEVANCE

Most commercially available devices for all-inside meniscal repair using ultrahigh-molecular-weight polyethylene suture provide fixation comparable to the classic vertical mattress suture repair technique in human cadaveric meniscus.

New suture method for radial tears of the meniscus: biomechanical analysis of cross-suture and double horizontal suture techniques using cyclic load testing

BACKGROUND

Repair of complete radial meniscal tears is a key to restoring the mechanical integrity necessary to maintain hoop tension in the meniscus. The primary stability of the meniscal repair is one of the most important factors for meniscal healing, but the biomechanical structural properties of different repair techniques for complete radial meniscal tears remain unknown.

HYPOTHESIS

Our novel cross-suture technique with suturing oblique to the collagen fibrils of the meniscus will yield better fixation than the standard double horizontal suture technique with suturing parallel to the collagen fibrils in the meniscus.

STUDY DESIGN

Controlled laboratory study.

METHODS

Biomechanical investigation was performed on 40 fresh human menisci (2 groups of 20 menisci each) from patients who underwent total knee arthroplasty. In the cross-suture technique group (group A), the sutures crossed over 5 mm from the tear and 5 mm and 10 mm from the rim. In the double horizontal suture technique group (group B), the sutures were parallel and had the same attachment points as group A. The specimens were cyclically loaded 500 times between 5 and 30 N and then loaded to failure after completion of the cyclic load testing.

RESULTS

Compared with the double horizontal suture group, the cross-suture group had a significantly higher ultimate failure load (78.96 ± 19.27 N vs 68.16 ± 12.92 N; P < .05), significantly greater stiffness (8.01 ± 1.54 N/mm vs 6.46 ± 1.12 N/mm; P < .05), and significantly lower displacement (5.74 ± 1.84 mm vs 8.56 ± 2.39 mm; P < .05) after a 500-cycle loading protocol.

CONCLUSION

Our cross-suture technique significantly improved the structural properties of the repaired complete radial meniscal tears.

CLINICAL RELEVANCE

The cross-suture technique for repair of radial meniscal tears provides high stability and could be a promising solution in young and in active patients.

Determination of the safe penetration depth during all-inside meniscal repair of the posterior part of the lateral meniscus using the FasT-Fix suture repair system

PURPOSE

The objective of this study was to determine the safe penetration depth of the FasT-Fix meniscal suture repair system during all-inside repair of the posterior part of the lateral meniscus.

METHODS

Thirty-one knees from 17 embalmed and formalin-fixed cadavers (11 women, 6 men) were used. In each case, the circumference of the cadaver knee was measured before dissection. After dissection, 41 Fast-Fix meniscal repair devices were used in different predetermined penetration depths ranging from 8 to 16 mm. In this study, non-involvement of the popliteal neurovascular bundle, common peroneal nerve or the inferior lateral genicular vessels by either needle penetration or affixment by the suture bar anchors was considered to be a safe trial.

RESULTS

Out of the 41 FasT-Fix devices used in this study, only one device bent during introduction and was excluded from the study. For the remaining 40 trials, 27 of them were considered safe, while 13 trials were considered unsafe. The ratio of the average penetration depth to the average circumference of the cadaver knee was found to be >0.05 for the unsafe penetrations, and this was statistically significant P < 0.05. Additionally, for the first point, which is more central, there was a trend for the straight needles through the direct lateral approach to be less safe, and this was found to be statistically significant P < 0.05.

CONCLUSIONS

Correlating the needle-penetration depth to the measured circumference of the cadaver knee may be an important clinical predictor of safety whereby a ratio of less than 0.05 might be useful as a guide to determine the safe penetration depth of the FasT-Fix suture repair needle during repair of the posterior horn lateral meniscus. Also, it is better to avoid using straight needles through the direct lateral approach during repair of the more central portion of the posterior horn lateral meniscus.

Inside-out medial meniscus suture: an analysis of the risk of injury to the popliteal neurovascular bundle

PURPOSE

To assess the risk of damage to the popliteal neurovascular structures when inserting the needle through the posterior aspect of the knee during inside-out suture of the posterior horn of the medial meniscus.

METHODS

The first stage of our study consisted of simulating a virtual meniscal suture during magnetic resonance imaging by tracing a line from 3 different points (located medially [MP], centrally [CP], and laterally [LP] to the patellar tendon) to the posterior horn of the medial meniscus. This procedure was undertaken both at rest and with valgus stress. The next phase involved the suture of the posterior horns of medial menisci taken from cadaveric specimens, the needle being inserted through 3 separate locations (again located medially [MP], centrally [CP], and laterally [LP] to the patellar tendon). Finally, the distance from each suture thread to the aforementioned neurovascular bundle was measured.

RESULTS

During the magnetic resonance imaging study, the measured distances at rest were 26.4 mm for MP, 28.8 mm for CP, and 31 mm for LP, whereas those recorded with valgus stress were 21.7 mm for MP, 23.6 mm for CP, and 26 mm for LP. In the second phase of the study (cadaveric specimen suture), the distances obtained were 22.6 mm for MP, 27.6 mm for CP, and 33 mm for LP.

CONCLUSIONS

Our results indicate that when the needle is inserted through the 3 points investigated into the posteromedial region of the knee (10 mm from the posterior horn of the internal meniscus) during inside-out suture, it is far enough from the popliteal neurovascular bundle for the maneuver to be performed with a reasonable safety margin. However, this margin can be increased further still if the needle is inserted into the joint through a point located laterally to the patellar tendon.

CLINICAL RELEVANCE

Inside-out suture performed 10 mm from the posterior horn of the internal meniscus through the portals studied offers a sufficient margin of safety to avoid damage to the popliteal neurovascular bundle.

The "butterfly" suture technique for meniscal repair

One of the important factors effecting meniscal healing is the strength of primary fixation obtained by repairing technique. From this perspective, it is important to choose the technique ensuring a higher primary fixation strength for meniscal repairs. We described a new technique for meniscal repair called "butterfly" technique using Viper device and hypothesized that high primary fixation strength can be obtained with this technique. The study was performed on calve knees. Full-thickness longitudinal tears 2 cm in length and 3 mm medial from the periphery were created in corpora of medial menisci of 14 calves. After creating tears, menisci were divided into two equal groups. In Group 1, two vertical loop sutures 1 cm apart were placed using a Viper device. Whereas in Group 2, tears were repaired using "butterfly" sutures. The mean load to failure was 156.3 ± 13.1 and 186 ± 15.8 N in Group 1 and 2, respectively (p = 0.002). The fixation strength in Group 2 was significantly higher than in Group 1. We suggest that, using Viper device and all-inside "butterfly" suturing techniques, meniscal ruptures with appropriate locations can be repaired with higher primary fixation strength.

Neurovascular safety and clinical outcome of outside-in repair of tears of the posterior horn of the medial meniscus

PURPOSE

The purpose of this study was to evaluate the safety and clinical outcome of a new posterior approach for the known outside-in technique for repair of tears of the posterior horn of the medial meniscus (PHMM).

METHODS

First, a cadaveric study was performed on 6 cadaveric knees to assess the safety of a point just lateral to the semitendinosus tendon as an entry point for outside-in repair. Dissection was done to measure the clearance of this point to the nearby popliteal bundle and saphenous nerve. A prospective case series study was then performed to assess the clinical outcome of such an approach. We treated 41 consecutive cases with PHMM tears by the outside-in technique using a shuttle relay method through the same point. Clinical assessments, magnetic resonance imaging findings, Lysholm scores, and International Knee Documentation Committee subjective scores were recorded for all patients. After a minimum postoperative period of 2 years, all cases were re-evaluated and re-scored.

RESULTS

The cadaveric study showed a mean clearance distance of 2.4 cm for the popliteal bundle and 4.6 cm for the saphenous nerve. The case series study was done on 41 meniscal repairs; 15 of 41 cases (37%) were performed in conjunction with anterior cruciate ligament reconstruction. There were 22 right knees (54%) and 19 left knees (36%). After a mean follow-up period of 27 months, patients showed a clinical success rate of 88% in terms of disappearance of pain, locking, and swelling, together with improved Lysholm scores (from 34 to 88) and International Knee Documentation Committee scores (from 25 to 88). These improvements were statistically significant (P < .05).

CONCLUSIONS

An outside-in repair technique with a posterior entry central to the semitendinosus tendon was used safely with 88% satisfactory clinical results for treatment of PHMM tears.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

Meniscal repair using the FasT-Fix device in patients with chronic meniscal lesions

The aim of this prospective study was to evaluate meniscal suturing using the FasT-Fix device for chronic meniscal tears. This procedure was carried out on 25 patients between 2006 and 2007. Nineteen patients were male and the median age was 31 (14-47) years. The median waiting time to surgery was 27 (6-80) months and the median follow-up was 20 (14-29) months. Eleven patients (44%) required reconstruction of an associated anterior cruciate ligament (ACL) injury. 20 patients (80%) showed medial meniscus tears. All tears were located in the red zone or red-white zone. According to Barett's criteria, meniscal tear healing was achieved in 21 patients (84%). Lysholm and Tegner scale scores improved from 60 (47-77) preoperatively to 95 (58-100) postoperatively and from 3 (2-6) preoperatively to 6 (3-9) postoperatively, respectively. There were no neurovascular complications. Revision surgery was necessary in one patient, in whom a partial meniscectomy was performed. The results obtained suggest that chronic meniscal tears in the zones described can be healed.

Cyclic testing of 3 all-inside meniscal repair devices: a biomechanical analysis

BACKGROUND

Despite the growing popularity of all-inside meniscal repair devices, concerns remain about their fixation strength. It is also unclear which of these devices have the most ideal biomechanical properties.

PURPOSE

To compare the biomechanical properties of 3 all-inside meniscal repair devices: the Meniscal Cinch, Ultra FAST-FIX, and MaxFire.

STUDY DESIGN

Controlled laboratory study.

METHODS

Twenty-seven human cadaveric menisci (3 groups of 9) were repaired using 3 different meniscal repair devices. The repaired menisci were then subjected to cyclic loading and load-to-failure testing. Gap formation and ultimate load to failure were measured.

RESULTS

Six of the devices failed during cyclic testing, 4 in the MaxFire group (44%), 1 in the Ultra FAST-FIX group (11%), and 1 in the Meniscal Cinch group (11%). After 1 cycle, there was a trend toward larger gap formation in the MaxFire group (3.65 mm) compared with the Meniscal Cinch group (2.12 mm, P = .05). After 100 cycles, group differences were found in gap formation (P = .03), with the MaxFire group exhibiting greater displacement (6.70 mm) than the Ultra FAST-FIX group (3.59 mm). After 500 cycles, group differences in gap formation (Meniscal Cinch, 5.94; Ultra FAST-FIX, 4.74 mm; Max Fire, 7.19 mm) did not reach statistical significance (P = .20). A trend was found toward higher ultimate load to failure in the Ultra FAST-FIX (86.1 N) and Meniscal Cinch (85.3 N) groups compared with the MaxFire group (64.5 N, P = .06). Stiffness was also higher in the Ultra FAST-FIX (25.2 N/mm) and Meniscal Cinch (25.5 N/mm) groups than the MaxFire group (16.3 N/mm, P = .02).

CONCLUSION

The Meniscal Cinch and Ultra FAST-FIX devices have more desirable biomechanical properties than the MaxFire as demonstrated by higher stiffness and a lower failure rate during cyclic testing.

CLINICAL RELEVANCE

The Meniscal Cinch and Ultra FAST-FIX devices may be more desirable implants for use during all-inside meniscal repair as they have superior biomechanical properties when compared with the MaxFire device.

Tensile forces on sutures in the human lateral knee meniscus

Tensile strength is the most often reported parameter in biomechanical investigations of meniscal repair techniques. However, the magnitude of the tensile forces that actually occur on repaired lesions is not clear. The purpose of this study was to investigate if tensile forces occur on repaired lateral meniscal lesions, which could exceed the failure strength of common repair techniques. In human knees (n = 6), vertical-longitudinal lesions 25 mm in length were created in the posterior horn of the lateral meniscus at a distance of 3 mm from the meniscosynovial junction and the popliteal hiatus. A braided steel wire, resembling a vertical suture, was inserted into the meniscal tissue and fitted with a force transducer. The knees were mounted in an apparatus, which simulated weight bearing and non-weight bearing conditions. Repeated measurements were conducted with both internal and external rotation at flexion angles of 0 degrees , 30 degrees , 60 degrees , 90 degrees and 120 degrees . Weight loading alone caused no tension on the suture. Combined flexion and rotation generated mean forces between 0.5 and 4.1 N. No significant effect of the flexion angle or direction of rotation was found. If a minimum strength of 10 N was assumed for the common meniscal repair techniques, the tensile forces were well below this limit under all circumstances (P < 0.001). These data indicate that, within the range of motion investigated, no significant tensile forces occur on longitudinal lateral lesions. Forces other than tension and biological factors are of greater importance for the healing. Therefore, the assessment of repair techniques should not be based on alone the ability to resist high distraction forces.

Biomechanical evaluation of arthroscopic all-inside meniscus repairs

Viper is a new device for arthroscopically all-inside meniscal repairing. In previous studies about Viper device, procedures were not applied arthroscopically despite this device has been designed for arthroscopic application. In this study, we evaluated primary fixation strength of arthroscopically applied meniscal repair using Viper device to obtain better clinical relevance. Two centimeter in length meniscal tear 2-3 mm far from periferic edge of medial meniscus of 50 calves were created arthroscopically. The menisci were divided into five groups including 10 menisci in each. In group 1, tears were repaired by outside-in vertical loop suture technique with No: 0 PDS. Tears were fixed by all-inside vertical suture by using Viper device with No: 0 PDS in group 2. In meniscal implant groups, RapidLoc, H-Fix, and Clearfix were applied in groups 3,4, and 5, respectively. Primary fixation strength of repairing techniques were evaluated with bio-mechanical testing machine. Fixation strengths determined in groups 1 and 2 were detected as 145 +/- 13 and 136 +/- 33 N, respectively. There was no difference in pull-out strength between groups 1 and 2. Fixation strengths in these two groups were significantly higher compared to groups 3, 4, and 5. There was no significant difference between group 3 (33 +/- 6 N) and 5 (28 +/- 6 N) in terms of fixation strengths whereas fixation strengths of these two groups were significantly higher compared to group 4 (20 +/- 3 N) (P = 0.005, P = 0.018, respectively). All-inside vertical suture technique using Viper device revealed comparable primary fixation strength with outside-in vertical suture technique for meniscal repair. We suggest that the Viper device is safe and reliable for meniscal repair.

Biomechanical testing of new meniscal repair techniques containing ultra high-molecular weight polyethylene suture

PURPOSE

To evaluate the biomechanical characteristics of current meniscal repair techniques containing ultra high-molecular weight polyethylene (UHMWPE) suture with and without cyclic loading.

METHODS

Vertical longitudinal cuts made in porcine menisci were secured with a single repair device. Noncycled and cycled (500 cycles) biomechanical tests were performed on the following groups: group 1, No. 2-0 Mersilene vertical suture (Ethicon, Somerville, NJ); group 2, No. 2-0 Orthocord vertical suture (DePuy Mitek, Westwood, MA); group 3, No. 0 Ultrabraid vertical suture (Smith & Nephew Endoscopy, Andover, MA); group 4, No. 2-0 FiberWire vertical suture (Arthrex, Naples, FL); group 5, vertically oriented mattress suture by use of an Ultra FasT-Fix device (Smith & Nephew Endoscopy) with No. 0 Ultrabraid; group 6, vertically oriented mattress suture by use of a RapidLoc A2 device (DePuy Mitek) with No. 2-0 Orthocord suture; group 7, vertically oriented stitch by use of a MaxFire device with MaxBraid PE suture (Biomet Sports Medicine, Warsaw, IN); and group 8, an obliquely oriented stitch of No. 0 UHMWPE suture inserted by use of a CrossFix device (Cayenne Medical, Scottsdale, AZ). Endpoints were failure loads, failure modes, stiffness, and cyclic displacement.

RESULTS

Mean single-pull loads were calculated for Ultra FasT-Fix (121 N), FiberWire (110 N), MaxFire (130 N), Mersilene (84 N), Orthocord (124 N), RapidLoc A2 (86 N), CrossFix (77 N), and Ultrabraid (109 N). After 500 cyclic loads, the Orthocord (222 N) repair was stronger than the others: Ultra FasT-Fix (110 N), FiberWire (117 N), MaxFire (132 N), Mersilene (89 N), RapidLoc A2 (108 N), CrossFix (95 N), and Ultrabraid (126 N) (P < .05). Ultrabraid suture showed significantly more elongation over 500 cycles than the other repairs (P < .05). The principal failure mode associated with the single destructive pull (suture breakage) changed to pulling through the meniscus after cyclic loading for most devices. Knot slippage or device failure was seldom observed as the failure mode with these techniques.

CONCLUSIONS

Self-adjusting, UHMWPE suture-containing meniscal repair devices (Ultra FasT-Fix, RapidLoc A2, and MaxFire) were comparable to the isolated UHMWPE-containing suture repairs on single-failure load testing. UHMWPE-containing suture repairs are stronger than braided polyester suture repairs, but pure UHMWPE suture (Ultrabraid) elongated more during cycling. Orthocord suture is significantly stronger than the other meniscal repair techniques after cyclic loading (P < .05).

CLINICAL RELEVANCE

Meniscal repair techniques using UHMWPE containing sutures provide greater strength than earlier generations of meniscal repair techniques.

FasT-Fix versus inside-out suture meniscal repair in the goat model

BACKGROUND

Recent all-inside meniscal repair devices are available, but in vivo studies with these devices are sparse.

HYPOTHESIS

The FasT-Fix has inferior meniscal healing compared with the inside-out suture technique in the goat model.

STUDY DESIGN

Controlled laboratory study.

METHODS

After Institutional Review Board approval, 73 male castrated goats (Capra hircus) underwent a 2-cm meniscal incision and subsequent repair with the FasT-Fix device on one knee and inside-out meniscal repair on the contralateral knee. Both repairs used a vertical mattress suture technique. Access to the menisci was via an open technique with an extra-articular osteotomy of the medial collateral ligament origin on the femur. The animals were then allowed to ambulate unrestricted in a pasture after a 7-day stay in cages. Necropsy was carried out 6 months postoperatively, and the menisci and articular cartilage were studied with gross and microscopic inspection.

RESULTS

Nine of the 73 animals were excluded before necropsy. A total of 64 animals underwent necropsy, gross measurement of residual lesions, gross evaluation for chondral damage, histologic evaluation of meniscal repair, histologic evaluation of any adjacent inflammatory reaction to implants, and data analysis. Compared with the inside-out group, the FasT-Fix group had longer residual full-thickness defects (1.2 +/- 2.9 mm vs 0.2 +/- 1.1 mm; P = .011) and longer residual partial-thickness defects (8.4 +/- 6.3 mm vs 3.6 +/- 5.5 mm; P < .001). A total of 148 FasT-Fix devices were placed for 73 knees. Two devices were replaced for improper deployment. The device deployed and attached correctly 146 of 148 times for a success rate of 98.6%. There was no gross chondral damage and no histologic findings of inflammatory reaction to the implants with either technique.

CONCLUSIONS

The FasT-Fix meniscal repair had inferior meniscal healing results in this animal model. Previous studies using this animal model have paralleled clinical outcomes. Implantation of the FasT-Fix device does not damage adjacent femoral or tibial cartilage. The deployment of the FasT-Fix implant was simple and reproducible. There was no inflammatory reaction to the FasT-Fix implant.

CLINICAL RELEVANCE

The FasT-Fix meniscal repair has inferior meniscal healing results compared with the inside-out meniscal repair technique in the goat model. The clinical significance of this finding is not known. Further clinical study of the FasT-Fix implant is warranted.

All-inside suture technique using anterior portals in posterior horn tears of lateral meniscus

Methods for the repair of meniscal tears include inside-out, outside-in, and all-inside techniques. In this article an all-inside technique is proposed for the posterior horn of the lateral meniscus that takes advantage of the capacious posterolateral recess when the knee is flexed. A device consisting of a large needle with a buttonhole in the tip (previously used for inside-out suture of the medial meniscus) is used. This technique uses only anterior portals (anteromedial and anterolateral portals and an accessory lateral or transpatellar tendon portal). The arthroscope is inserted through the accessory portal. Once the tear has been located and its edges refreshed, the suture device is placed anterolaterally. The tip of the needle is loaded with suture and passed through both sides of the tear and into the posterolateral recess of the knee (without exiting the capsule). The suture tail is recovered with the use of a suture retriever through the anteromedial portal. Next, the suture retriever is inserted through the anterolateral portal to once again retrieve and shuttle the tail before completion of an arthroscopic knot. In addition to the ease of the technique, use of this simple, reusable device adds the benefit of low cost when compared with other techniques.

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.

Biomedical devices in meniscal repair

Preservation of the menisci is increasingly emphasized in orthopedic care of the knee. Techniques are rapidly emerging that allow easier accomplishment of this goal. In particular, the development of all-inside arthroscopic meniscal repair devices has facilitated more ready repair. A number of laboratory and clinical studies have examined these devices and comparisons with more traditional techniques have been made. Numerous reports of potential complications from these new technologies have also been described in the literature. This review covers the current options for treatment of meniscal repair, laboratory and clinical data, and also potential complications.

The "cruciate suture" for arthroscopic meniscal repair: a new technique

Meniscal repair has become the treatment of choice whenever a reparable tear is diagnosed. Fixation strength of the repair technique is always of paramount importance in comparison of various techniques, especially after the evolution of many arthroscopic all-inside devices. We present a new arthroscopic meniscal repair suturing technique called "cruciate suture." One 18-gauge needle and suture material are used. The needle is loaded with the suture material from its tip. The suture is folded at the tip of the needle, which is inserted to penetrate the skin obliquely to appear inside the joint, making a loop. The needle is retracted, while the suture is kept inside of it. The needle is reinserted at the same hole, appearing inside the joint and making a second loop. The needle is retracted completely. With the use of a probe, the loop at the second point is pulled through the loop at the first point, thereby forming a free end. The 2 limbs of the loop are pulled, thus driving the limb with the free end outside of the joint. The first oblique vertical suture is completed at this point. The needle is reloaded by the suture limb from the first point. The previous procedure is repeated, with use of the second skin hole and the third and fourth points to make the second oblique vertical suture. The cruciate suture is now complete. We tested the ultimate tension load (UTL) of the cruciate suture in comparison with that of the vertical suture (the gold standard). A total of 36 tests (18 for the cruciate suture and 18 for the vertical suture) were performed on human menisci. The mean UTL of the cruciate suture was measured at 110 N; the mean UTL of the vertical suture was 67 N.

Effect of lesion location on fixation strength of the meniscal viper repair system: an in vitro study using porcine menisci

PURPOSE

The Meniscal Viper Repair System (Arthrex, Naples, FL) is a novel suture-based all-inside meniscal repair system. This study was performed to test whether the Meniscal Viper Repair System would provide superior fixation characteristics for vertical longitudinal meniscal lesions located closer to the periphery compared with those located further away from the periphery.

METHODS

Vertical longitudinal lesions were created either 1 to 2 mm or 3 to 4 mm away from the periphery of porcine menisci. After repair with the Meniscal Viper Repair System, fixation characteristics were studied during cyclic (500 cycles, 5 to 50 N) and load to failure testing (5 mm/min) in a servo hydraulic device.

RESULTS

Meniscal lesion repair location did not show significant differences in displacement or stiffness during cyclic testing. During load to failure testing, meniscal lesion repairs located 1 to 2 mm from the periphery showed superior load at failure (188.8 +/- 45.4 N) compared with repairs located 3 to 4 mm from the periphery (114.4 +/- 35.0 N) (P = .01). Stiffness and displacement during load to failure testing did not show statistically significant differences.

CONCLUSIONS

The Meniscal Viper Repair System provides stronger meniscal repair strength when lesions are located within 1 to 2 mm of the periphery.

CLINICAL RELEVANCE

The Meniscal Viper Repair System is better suited for repair of peripheral meniscal lesions located within 1 to 2 mm of the periphery. For lesions located in zone 2 (within the central 50%), careful assessment of their distance from the periphery is recommended. For lesions located more than 3 to 4 mm away from the periphery, alternative repair systems or augmentation with other devices may be prudent.