Biomechanical properties under cyclic loading of seven meniscus repair techniques

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 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.

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

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

The effect of inclination angle on the strength of vertical mattress configuration for meniscus repair

PURPOSE

Vertical mattress configuration is the strongest of all other configurations and the repairing devices of meniscus repair. The purpose was whether increasing the inclination angle between two strands of the vertical mattress configuration by increasing the amount of meniscus tissue captured would enhance the initial strength of the construction.

METHODS

A 2-cm long anteroposterior vertical longitudinal incision was created in two groups of bovine medial menisci. In the first group, the distance between the two vertical suture strands and the vertical horizontal sutures on the capsular side of the meniscal lesion was 2 mm (Group 1). In the second group, the distance was 5 mm (Group 2). The following repair specimens underwent cyclic loading prior to loading the failure testing. The endpoints included ultimate failure load (N), stiffness (N/mm) and cyclic displacement (mm) after the 100 cycles and the mode of failure.

RESULTS

Group 1 (2 mm) (90.7 (±19.9) N) had lower ultimate load than Group 2 (5 mm) (120.8 (±24.5)) (P < 0.05). Stiffness and displacements during the cycling were not different between the groups (n.s.). All specimens failed by suture rupture.

CONCLUSION

Increased inclination angle with increased distance between the two vertical suture strands on the capsular side of the meniscal lesion resulted in higher failure load compared to control group with lower inclination angle and distance on the capsular side.

Horizontal suture placement influences meniscal repair fixation strength

PURPOSE

This in vitro biomechanical study investigated the influence of horizontal suture placement distance from the medial meniscal lesion repair site on fixation characteristics during submaximal cyclic and load to failure test conditions.

METHODS

Eighteen cadaveric (20-45 years of age) medial menisci with intact joint capsules were harvested within 24-48 h after death and divided into two groups of 9 specimens each for biomechanical testing. A 2.0-cm-long antero-posterior vertical longitudinal lesion was created with a #15 scalpel 2.0-3.0 mm from the outer edge of each meniscus. Menisci were repaired using #2-0 suture material with two horizontal suture loops placed either 1.0 mm (Group 1) or 3.0 mm (Group 2) from the lesion site. Following repair, the lesion was extended completely through the meniscal horns so that no tissue secured the repair, only the two horizontal suture loops representing a "worst-case" testing scenario. Following repair, specimens were placed in a servo hydraulic device using a pair of 1.2-mm-diameter steel wire loops and underwent submaximal cyclic loading between 5 and 50 N (1 Hz) for 500 cycles prior to load to failure testing (5 mm/min crosshead speed, 20 Hz data collection). An alpha level of P < 0.05 was selected to indicate statistical significance.

RESULTS

Five of nine (55.6 %) Group 1 specimens did not complete submaximal cyclic testing. All Group 2 specimens completed submaximal cyclic testing (Fisher's exact test P = 0.029). Statistically significant mean group differences were not observed for displacement during submaximal cyclic loading (Group 1 = 5.0 ± 1.5 mm and Group 2 = 5.7 ± 1.6 mm) or for construct stiffness during load to failure testing (Group 1 = 50.1 ± 6.3 N/mm and Group 2 = 52.6 ± 11.9 N/mm). Group 2 displayed greater mean load at failure (112.1 ± 40.8 N vs. 72.7 ± 11.2 N, P = 0.02) and mean displacement at failure (11.1 ± 2.2 mm vs. 7.6 ± 1.4 mm, P = 0.03) than Group 1.

CONCLUSIONS

Horizontal sutures placed slightly farther away from the meniscus lesion displayed superior repair fixation than sutures placed closer to the lesion. The superior biomechanical meniscal repair fixation provided by capturing greater tissue volume may enable safe earlier participation in functional exercise activities. Studies are needed to verify these findings in vivo.

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.

Influence of test temperature on biomechanical properties of all-inside meniscal repair devices and inside-out meniscus sutures--evaluation of an isolated distraction loading, worst-case scenario

BACKGROUND

Studies on the biomechanical properties of meniscus repairs are usually performed at room instead of body temperature. However, various all-inside meniscal repair devices include bioabsorbable materials, which are mechanically sensitive to higher environmental temperatures. Therefore, we hypothesize that current test standards may systematically lead to a false overestimation of their performance.

METHODS

In 84 cadaveric bovine lateral menisci, an artificial vertical lesion was repaired with different all-inside meniscal repair devices (FasT-Fix, FasT-Fix AB, RapidLoc, Meniscus Arrow, Meniscus Screw) compared to a vertical inside-out Ethibond Excel 2.0 suture loop. Maximum load-to-failure, stiffness, and failure mode were tested in a uniaxial distraction loading at 20°C and 37°C.

FINDINGS

Most of the tested implants were not susceptible to the higher environmental test temperature with respect to maximum load-to-failure, stiffness, and failure mode. Only the RapidLoc showed a significantly decreased stiffness (-28.1%) and a statistical trend to lower maximum load-to-failure (-20.6%) at 37°C compared to 20°C.

INTERPRETATION

20°C environmental temperature seems to be an acceptable test condition for the most meniscal repair devices. However, if the bioabsorbable part of the implant is the weakest link, body temperature may be considered for testing to prevent false overestimation of the biomechanical properties. For future biomechanical in vitro testing of meniscal repair devices, this study may provide novel insight into biomechanical test protocols for considering the environmental test temperature as an influencing factor of the biomechanical properties of especially bioabsorbable meniscal repair devices.

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

BACKGROUND

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

PURPOSE

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

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

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

RESULTS

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

CONCLUSIONS

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

Meniscal repair using large diameter horizontal sutures increases fixation strength: an in vitro study

PURPOSE

the purpose of this study was to compare the mechanical characteristics of meniscal repair fixation using horizontal sutures and two different diameter sutures under submaximal cyclic and load to failure test conditions.

METHOD

a 2-cm long anteroposterior vertical longitudinal incision was created in two groups of bovine medial menisci. Lesions were repaired using either #2-0 (Group 1), or #2 (Group 2) Fiberwire suture. Following repair, the lesion was extended through the posterior and anterior meniscal horns so that no tissue secured the repair site. Specimens underwent submaximal cyclic (5-50 N at 1 Hz for 500 cycles) and load to failure testing (5 mm/min crosshead speed) in a servo hydraulic device. Specimen failure mode was verified by the primary investigator. An alpha level of P < 0.05 was selected to indicate statistical significance.

RESULTS

group 2 displayed greater load at failure (132.1 ± 54.4 N) than Group 1 (91.9 ± 26.2 N) (P = 0.02). Group 2 also displayed greater stiffness (47.1 ± 8.3 N/mm) than Group 1 (38.5 ± 10.2 N/mm) (P = 0.03). The failure mode for all specimens was suture pull-through the meniscal tissue. Larger diameter suture provided superior mechanical meniscal fixation.

CONCLUSION

if horizontal suture would be used in meniscal repair, the most suitable larger diameter suture should be used.

Strategies for repair of radial tears close to the meniscal rim--biomechanical analysis with a cyclic loading protocol

BACKGROUND

Lateral meniscectomy contributes to early-onset osteoarthritis. Biomechanical properties of sutures repairs for complete radial meniscal tears remain unknown.

HYPOTHESIS

Double horizontal suture techniques for repair of radial meniscal tears with a shorter distance from the meniscal rim provide significantly higher structural properties than do comparable single-suture techniques with a wider distance from the meniscal rim.

STUDY DESIGN

Controlled laboratory study.

METHODS

In 55 fresh-frozen porcine menisci, standardized complete radial meniscal tears were repaired with different distances from the meniscal rim and tear edges and with different numbers of sutures. In group A, the suture was 4 mm from the tear and 8 mm from the meniscal rim; group B, 2 mm from tear; group C, 2 mm from tear, 12 mm from rim; group D, double-loop technique, 2 mm from tear, 5 mm and 10 mm from rim; group E, longitudinal tear sutured with 1 loop, 8 mm from rim, and 4 mm between stitches. The specimens were cyclically loaded 1000 times between 5 and 20 N and loaded to failure.

RESULTS

All repaired constructs survived the cyclic loading protocol. Compared with the single-loop techniques, the double-loop technique (group D) showed a significantly higher maximum load and yield load and significantly lower displacement after 1000 cycles. Compared with group B, group C had a higher displacement after 1000 cycles (P < .05), and its stiffness showed a descriptive negative trend (P = .09). Displacement after cycling testing in group C was higher than in groups B and D (P < .05).

CONCLUSION

Repair of radial meniscal tears with a second suture and shorter distance from the meniscal rim has a positive influence on primary stability. Different distances from tear edges apparently have no influence on structural properties.

CLINICAL RELEVANCE

Horizontal sutures for repair of radial meniscal tears provide high stability and can be enhanced with a second horizontal suture and shorter distance from the meniscal rim.

Articular contact pressures of meniscal repair techniques at various knee flexion angles

Articular cartilage injury can occur after meniscal repair with biodegradable implants. Previous contact pressure analyses of the knee have been based on the tibial side of the meniscus at limited knee flexion angles. We investigated articular contact pressures on the posterior femoral condyle with different knee flexion angles and surgical repair techniques. Medial meniscus tears were repaired in 30 fresh bovine knees. Knees were mounted on a 6-degrees-of-freedom jig and statically loaded to 200 N at 45 degrees, 70 degrees, 90 degrees, and 110 degrees of knee flexion under 3 conditions: intact meniscus, torn meniscus, and meniscus after repair. For each repair, 3 sutures or biodegradable implants were used. A pressure sensor was used to determine the contact area and peak pressure. Peak pressures over each implant position were measured. Peak pressure increased significantly as knee flexion increased in normal, injured, and repaired knees. The change in peak pressure in knees with implant repairs was significantly higher than suture repairs at all knee flexion angles. Articular contact pressure on the posterior femoral condyle increased with knee flexion. Avoidance of deep knee flexion angles postoperatively may limit increases in articular contact pressures and potential chondral injury.

Practice patterns for combined anterior cruciate ligament and meniscal surgery in the United States

PURPOSE

The purpose of the study was to compare frequency of meniscal repair to partial meniscectomy in patients undergoing anterior cruciate ligament reconstruction using the American Board of Orthopaedic Surgeons (ABOS) database.

HYPOTHESES

(1) Practice patterns are similar with respect to geographic region. (2) Surgeons with fellowship training perform more meniscal repairs compared with general orthopaedic practitioners. (3) Younger patients are more likely to be treated with meniscal repair at the time of anterior cruciate ligament reconstruction. (4) The frequency of meniscal repair in conjunction with anterior cruciate ligament reconstruction has increased over time.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

Information was extracted from the ABOS database from 2002 orthopaedic surgeons who sat for the part II examination from 2003 to 2007. The database was queried for all patients who underwent anterior cruciate ligament reconstruction (Current Procedural Terminology [CPT] code 29888) without or with meniscectomy (CPT 29881) or meniscal repair (CPT 29882). Factors affecting meniscal surgery that were investigated included patient age, geographic region of practice, fellowship training, and declared subspecialty of the surgeon.

RESULTS

On average there were 52,000 cases per year registered in the ABOS database, approximately 1700 of whom underwent anterior cruciate ligament reconstruction. Meniscal repair was most frequently performed in the Southwest region (18.6%, P < .001) and least frequently in the Northwest region (11.3%, P < .001). Combined anterior cruciate ligament reconstruction and meniscal repair was performed significantly more often by fellowship-trained surgeons (17%) than by surgeons with other fellowship training (12%) or no fellowship training (12%, P < .001) and in patients younger than age 25 years (19%) compared with those age 40 years and older (8%, P <.001). Meniscal repair was performed in 13.9% of anterior cruciate ligament reconstructions in 2003 and in 16.4% of anterior cruciate ligament reconstructions in 2007 (P > .05).

CONCLUSION

Combined anterior cruciate ligament reconstruction with meniscal repair was more frequent for younger patients and by surgeons with sports fellowship training. Concomitant meniscal repair is performed by fellowship-trained surgeons in this study in only 18% of anterior cruciate ligament reconstructions.

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

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

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.

A biomechanical comparison of all-inside meniscus repair techniques

BACKGROUND

The aim of this study was to assess the biomechanical characteristics of six all-inside meniscal single suture repair techniques using a porcine model.

MATERIALS AND METHODS

Peripheral longitudinal tears were created in freshly isolated porcine menisci. Tears were repaired using the single vertical technique with six different repair complexes including those involving sutures (#2 FiberWire, #2 Ethibone, flexible anchors (Fast-Fix, RapidLoc), and rigid anchors (Meniscal-Dart, BioStinger). Displacement, ultimate failure strength, stiffness, and site of failure were measured using a Materials Testing System machine. An initial 2 N preload was applied, followed by loading between 5 and 20 N for 300 cycles. Failure strength was determined lastly by increasing tension at a rate of 5 mm/min until failure.

RESULTS

Failure strength was highest in the #2 FiberWire group (175.6 N). This was significantly higher than in all other groups (P < 0.05). The second highest failure load was evident in the #2 Ethibone group (113.8 N). This was significantly higher than in all other groups bar the #2 FiberWire group (P < 0.05). Stiffness was also significantly higher in the #2 FiberWire group compared with all other groups (8.5 N/mm, P < 0.05). There were no between-group differences in displacement. When grouped by repair technique, failure load was significantly higher, and displacement was significantly lower, in suture compared with both flexible and rigid anchor repaired menisci (P < 0.01 for all comparisons). Although stiffness was also higher in the suture group, there were no significant between-group differences detected.

CONCLUSIONS

Suture techniques exhibited biomechanical superiority over biodegradable flexible and rigid anchor devices for meniscus repair.

A cyclic testing comparison of FasT-Fix and RapidLoc devices in human cadaveric meniscus

INTRODUCTION

Cyclic testing may provide a more valid depiction of how arthroscopic meniscal repairs will withstand the forces of activities of daily living (ADLs) and therapeutic exercises early post-surgery than single cycle load to failure testing. This study compared the meniscal fixation provided by vertically or horizontally placed FasT-Fix devices to horizontally placed RapidLoc devices under submaximal cyclic test conditions.

MATERIALS AND METHODS

Eighteen human cadaveric menisci were divided into three groups of six specimens. A scalpel was used to create a 2 cm lesion at 3 mm from the outer edge of the posterior third of each specimen. Merselene tape loops were placed around each side of the lesion and the tears were repaired using two vertical FasT-Fix, two horizontal FasT-Fix, or two RapidLoc devices. Cyclic testing (5-50 N at 1 Hz for 500 cycles) was performed on a servo hydraulic device. One-way ANOVA and Scheffe post-hoc tests were used to evaluate group differences (P < 0.05).

RESULTS

The vertical FasT-Fix group had less displacement over the initial ten loading cycles compared to the RapidLoc group (P = 0.004), but did not differ from the horizontal FasT-Fix group (P = 0.07). At 50, 100, 200, 300, 400, and 500 cycles, the vertical FasT-Fix group had less displacement than the horizontal FasT-Fix or RapidLoc groups (P < or = 0.004). At each interval the vertical FasT-Fix group had greater relative stiffness than the other groups (P < or = 0.009).

CONCLUSIONS

The vertical FasT-Fix group had comparatively less displacement (primarily repair site gapping) and greater relative stiffness.

The extent of laceration of circumferential fibers with suture repair of the knee meniscus. Winner of the AGA DonJoy award 2006

INTRODUCTION

Cannulas used with suture based meniscal repair techniques can potentially injure the load transmitting fibers of the meniscus. The subject of this study was to quantify this effect in a porcine in vitro model.

MATERIALS AND METHODS

From fresh frozen medial porcine menisci tissue specimens were harvested following the course of the peripheral circumferential fibers bundles. In the first part of the study the tissue samples were perforated with the cannulas of either a Fast Fix or a Rapidloc device or with an 18-gauge needle. The specimens were then visually inspected for fiber damage using low power microscopy and the mean size of the laceration was measured. Finally, the extent of the tissue laceration was indirectly determined using non-contact strain measurements of the samples before and after puncture.

RESULTS

When advanced with the cutting edge perpendicular to the fibers, the cannulas consistently cut the fibers while those were rather separated with the opposite orientation. It could be shown that specimens with a mean width of 8.1 mm lost 25% of the load transmitting cross section when being perforated two times with a Fast Fix device (P < 0.001). This effect is negated when the cannula was oriented in line with the fibers.

CONCLUSIONS

Cannulas used for suture based meniscal repair can cause a substantial laceration of the meniscal tissue. The effect strongly depends on the orientation of the cutting edge of the cannula relative to the course of the fibers and can thus potentially be avoided by an appropriate handling and design.

Meniscal screw fixation provides sufficient stability to prevent tears from gapping

BACKGROUND

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

METHODS

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

FINDINGS

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

INTERPRETATION

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

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.

Elongation and structural properties of meniscal repair using suture techniques in distraction and shear force scenarios: biomechanical evaluation using a cyclic loading protocol

BACKGROUND

Most biomechanical studies on meniscal repairs have focused on testing distraction scenarios to evaluate structural properties of the repaired meniscus. An application of shear forces might replicate the in vivo situation more closely.

HYPOTHESIS

In the shear force scenario, meniscal repair using a vertical suture technique will result in significantly less elongation when subjected to a cyclic loading protocol than that resulting from a horizontal suture technique.

STUDY DESIGN

Controlled laboratory study.

METHODS

In fresh-frozen porcine menisci (n = 10 in each group), horizontal and vertical 2.0 Ethibond suturing techniques were tested in distraction and shear force scenarios. Elongation after 1000 cycles between 5 and 20 N and the structural properties such as stiffness, yield load, maximum load to failure, and failure mode were evaluated using a testing machine at a rate of 12.5 mm/s.

RESULTS

In the distraction force scenario, no statistically significant difference in elongation after cyclic loading was found between specimens repaired with vertical or horizontal suture techniques. After 1000 cycles of cyclic loading in the shear force scenario, the horizontal suturing revealed significantly less elongation (2.8 +/- 1.1 mm) than did the vertical suture technique (4.6 +/- 2.0 mm). No statistically significant difference in yield and maximum load was found (P > .05).

CONCLUSION

The results of the present study do not support the authors' hypothesis. In the shear force test, horizontal sutures were superior to vertical suture techniques.

CLINICAL RELEVANCE

Meniscal repair with horizontal suture techniques can withstand elongation due to shear forces more effectively than can vertical mattress sutures.

A biomechanical comparison of the FasT-Fix meniscal repair suture system and the RapidLoc device in cadaver meniscus

PURPOSE

This biomechanical study compared the fixation characteristics of horizontally or vertically implanted FasT-Fix devices (Smith & Nephew, Endoscopy Division, Andover, MA) consisting of two 5-mm PLLA suture T-bar anchors with a pretied self-sliding knot (No. 0 nonabsorbable, USP, braided polyester suture material) and the RapidLoc device (Mitek Surgical Products, Westwood, MA) consisting of a PLLA T-bar anchor or "backstop," a connecting suture (No. 2 nonbiodegradable Ethibond; Ethicon, Somerville, NJ), and a PLLA grommet, for repairing posterior third lesions in human menisci.

TYPE OF STUDY

Controlled laboratory biomechanical study.

METHODS

After repair of a vertical longitudinal meniscus lesion with either vertically or horizontally implanted FasT-Fix devices or RapidLoc devices, 3 groups of 6 specimens underwent cyclic loading (5 mm/minute, cycling between 5 and 50 N at 1 Hz for 500 cycles) before load to failure testing on a servo hydraulic device. One-way analysis of variance and Tukey HSD post hoc tests were used to evaluate group differences (P < .05).

RESULTS

The vertical FasT-Fix device group (3.2 +/- 0.49 mm) had less displacement after cyclic testing than either the horizontal FasT-Fix (4.4 +/- 0.73 mm, P = .003) or the RapidLoc (4.6 +/- 0.22 mm, P = .002) device groups. The vertical FasT-Fix device group had greater stiffness during cyclic testing (14.4 +/- 2.1 N/mm) than the horizontal FasT-Fix (10.4 +/- 1.6 N/mm, P = .0001) or the RapidLoc (9.7 +/- 0.44 N/mm, P = .0001) device groups. During load to failure testing, the vertical FasT-Fix group (125.3 +/- 39 N) had 28% greater strength than the horizontal FasT-Fix device group (89.7 +/- 14 N, P = .02) and 30% greater strength than the RapidLoc device group (87.1 +/- 13 N, P = .028), whereas displacement and stiffness did not show statistically significant group differences.

CONCLUSIONS

The vertical FasT-Fix group had superior biomechanical characteristics for meniscal fixation during cyclic and load to failure testing compared with horizontal FasT-Fix or RapidLoc devices.

CLINICAL RELEVANCE

Although the RapidLoc devices provided fixation characteristics comparable to horizontally implanted FasT-Fix devices, vertically implanted FasT-Fix devices may provide superior all-inside fixation.

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

BACKGROUND

The biomechanical characteristics of the Meniscal Viper Repair System have not been previously studied.

HYPOTHESIS

Comparable meniscal lesion fixation standards will exist among the Meniscal Viper Repair System, the vertical FasT-Fix device, and vertical mattress sutures.

STUDY DESIGN

Controlled laboratory study.

METHODS

Porcine menisci (3 groups of 7 menisci each) were repaired using different devices. A servohydraulic device cycled each construct between 5 N and 50 N for 500 cycles before load to failure (5 mm/min). Group differences were evaluated with 1-way analysis of variance and Tukey post hoc tests.

RESULTS

During cyclic testing, the vertical mattress suture group (2.3 +/- 0.2 mm) showed less mean displacement than did the vertical FasT-Fix or the Viper system groups (3.9 +/- 0.7 mm and 3.9 +/- 0.5 mm, respectively); the vertical mattress suture group (21.8 +/- 2 N/mm) also displayed superior mean stiffness to the vertical FasT-Fix or the Viper system groups (13.2 +/- 2 N/mm and 13.1 +/- 1.8 N/mm, respectively). During load-to-failure testing, the vertical FasT-Fix group (145.9 +/- 9 N) withstood greater mean loads than did the Viper system group (111.2 +/- 30 N), but it did not differ significantly from loads withstood by the vertical mattress suture group (133.4 +/- 10 N). The Viper system and vertical FasT-Fix groups (14.6 +/- 2 N/mm and 12.1 +/- 1 N/mm, respectively) displayed superior mean stiffness to the vertical mattress suture group (9.8 +/- 0.5 N/mm) during load-to-failure testing.

CLINICAL RELEVANCE

Standard vertical mattress sutures provided superior fixation during cyclic loading compared with the 2 all-inside methods of suture fixation, suggesting a potential for better meniscal lesion healing with vertical mattress sutures when confronted with the stresses associated with early, progressive rehabilitation activities. Stronger sutures and less meniscal segment purchase in tears located 3 to 4 mm from the periphery may contribute to the failure of the Viper repair system.

Measurement of meniscofemoral contact pressure after repair of bucket-handle tears with biodegradable implants

INTRODUCTION

Biodegradable implants are frequently used for meniscus repair. Articular cartilage damage has been reported recently after meniscus repair with biodegradable implants. The aim of the study was to investigate the meniscofemoral contact pressure at the posterior horn of the medial and lateral meniscus after repair of bucket-handle lacerations.

MATERIALS AND METHODS

Specimens were mounted in a materials testing machine (Bionix 858, MTS) which was equipped with a load cell. The quadriceps tendon was attached to a hydraulic cylinder, and knee motion was controlled via tension of the quadriceps tendon. A piezo-resistive system (Tekscan, Boston, MA, USA) measured the meniscofemoral contact pressure. Five different types of biodegradable implants (Arrow, Dart, Fastener, Stinger and Meniscal Screw) and horizontal suture (no. 2 Ethibond) were tested. The knee was extended from 90 degrees of flexion to 0 degrees under a constant load of 350 N due to adjustment of the tension force of the quadriceps tendon. The femorotibial pressure and contact area were recorded at 0 degree, 30 degrees, 60 degrees and 90 degrees of flexion.

RESULTS

The meniscofemoral pressure did not increase after meniscus repair with biodegradable implants or sutures. The meniscofemoral peak pressure at the posterior horn was 1.46+/-1.54 MPa in the medial compartment and 1.08+/-1.17 MPa in the lateral compartment at full knee extension. The meniscofemoral pressure increased significantly in both compartments with knee flexion from 0 degree to 90 degrees.

CONCLUSION

Biodegradable implants for meniscus repair do not affect the meniscofemoral pressure. However, there remains a risk of damage to the cartilage when barbed implants are used. If the implant is not entirely advanced into the meniscus, the sharp head or some of the barbs at the column of the implant may come into direct contact with the articular cartilage of the femoral condyle or tibial plateau. The authors presume that incorrect positioning of the implant seems to be the major reason for cartilage damage.

Cyclic testing of flexible all-inside meniscus suture anchors: biomechanical analysis

BACKGROUND

Flexible meniscus repair devices are designed to combine the benefits of rigid all-inside meniscus anchors with the biomechanical properties of sutures.

HYPOTHESIS

Stiffness and pull-out strength of flexible all-inside suture anchors and conventional sutures under cyclic loading conditions will be comparable.

STUDY DESIGN

Controlled laboratory study.

METHODS

In 50 fresh frozen bovine menisci, artificial meniscus lesions were repaired with different meniscus fixation techniques: horizontal and vertical FasT-Fix, RapidLoc, and horizontal and vertical 2-0 Ethibond sutures. The specimens were cycled 1000 times between 5 and 20 N and then loaded to failure.

RESULTS

All devices survived the cyclic loading protocol. There was no significant difference in the displacement between all repair techniques tested (horizontal FasT-Fix, 6.23 mm; vertical FasT-Fix, 5.34 mm; RapidLoc, 6.84 mm; horizontal 2-0 Ethibond, 6.03 mm; vertical 2-0 Ethibond, 5.61 mm (P > .05). Vertical and horizontal FasT-Fix suture anchors had a significantly higher stiffness and pull-out strength (94.1 N and 80.8 N, respectively) than did horizontal sutures (50.2 N) and RapidLoc devices (30.3 N) (P > .05).

CONCLUSIONS

In this study, flexible all-inside meniscus anchors (FasT-Fix) had higher pull-out strength than did conventional vertical suture techniques. Biomechanical characteristics of the flexible RapidLoc are comparable to those of horizontal sutures.

CLINICAL RELEVANCE

Flexible all-inside meniscus repair devices are an alternative to conventional suture techniques.

Photochemical tissue bonding using monomeric 4-amino-1,8-naphthalimides

Certain substituted naphthalimides have been shown to produce, on photochemical activation, mechanically viable bonds between a variety of tissue surfaces. It is believed that these compounds act as photochemically activated oxidants, catalyzing the formation of reactive intermediates in the extracellular matrices of approximated tissue surfaces. The condensation of these intermediates results in the formation of crosslinks between the intimate surfaces. Of particular interest is the application of this technique to the repair of tears in the typically unrepairable avascular zone of menisci. The menisci are collagen-rich fibrocartilaginous tissues that support up to 90% of the load across the knee joint and participate in important functions including shock absorption, joint stabilization, hyperextension prevention, and lubrication of the knee. Preliminary ex vivo and in vivo work in our laboratories has demonstrated that photochemically activated naphthalimides have significant potential for the repair of meniscal lesions. We describe preliminary ex vivo studies assessing the relative abilities of a variety of water-soluble monomeric 4-amino-1,8-naphthalimides to bond bovine knee meniscal tissue on visible light irradiation.

A new rigid biodegradable anchor for meniscus refixation: biomechanical evaluation

All-inside repair devices have been developed to overcome the disadvantages of conventional suture techniques (such as vein and nerve damage and increased OR time). The Contour Meniscus Arrow is a second generation of the first biodegradable all-inside implant, the Meniscus Arrow. The aim of this study was to compare the biomechanical properties of the Contour Meniscus Arrow to the first-generation Meniscus Arrow and vertical or horizontal suture techniques. In fresh frozen bovine menisci, initial fixation strength, stiffness and failure mode of four different meniscus refixation techniques (Meniscus Arrow, Contour Meniscus Arrow, vertical and horizontal 2-0 Ethibond suture techniques) were evaluated in a computer-based material-testing machine at a rate of 12.5 mm/s. Vertical meniscus sutures showed the highest initial fixation strength, followed by the horizontal suture technique and the Contour Arrow. The Meniscus Arrow showed inferior pull-out strength. Subjecting the different refixation techniques to cyclic testing decreased the fixation strength in all groups. The modified Meniscus Anchor (Contour Arrow) provides biomechanical properties that are superior (pull-out strength) or similar (stiffness) compared to the first biodegradable all-inside implant, the Meniscus Arrow. The pull-out strength of the Contour Arrow was comparable to the pull-out strength reported for horizontal meniscus sutures in the literature. These biomechanical characteristics of this new implant justify clinical use.

Initial fixation strength of flexible all-inside meniscus suture anchors in comparison to conventional suture technique and rigid anchors: biomechanical evaluation of new meniscus refixation systems

BACKGROUND

The newest generation of meniscus repair devices is designed to combine the benefits of the all-inside technique with the biomechanical properties of sutures.

HYPOTHESIS

New flexible all-inside suture anchors have better fixation strength than rigid anchors, but there is no difference when compared to conventional horizontal and vertical mattress sutures.

STUDY DESIGN

Controlled laboratory study.

METHODS

In fresh-frozen bovine menisci, initial fixation strength, stiffness, and failure mode of different meniscus fixation techniques (FastT-Fix, RapidLoc, Meniscus Arrow, horizontal and vertical 2.0 Ethibond sutures) were evaluated in a computer-based materials testing machine at a rate of 12.5 mm/sec.

RESULTS

The vertical and horizontal FastT-Fix suture anchors were the strongest devices with regard to pullout strength, with no significant difference compared to the vertical 2-0 Ethibond sutures. Horizontal sutures, Meniscus Arrow, and RapidLoc had significantly lower pullout strength. Vertical and horizontal FastT-Fix suture anchors showed significantly higher stiffness than the other devices.

CONCLUSIONS

Biomechanical properties of flexible all-inside meniscus anchors (FastT-Fix) are comparable to conventional vertical suture techniques. Characteristics of the flexible RapidLoc are comparable to rigid anchors (Meniscus Arrow).

CLINICAL RELEVANCE

From the biomechanical point of view, flexible all-inside meniscus refixation devices are an alternative to conventional suture techniques and rigid meniscus anchors.

Tissue engineering of the meniscus

Meniscus lesions are among the most frequent injuries in orthopaedic practice and they will inevitably lead to degeneration of the knee articular cartilage. The fibro-cartilage-like tissue of the meniscus is notorious for its limited regenerative capacity. Tissue engineering could offer new treatment modalities for repair of meniscus tears and eventually will enable the replacement of a whole meniscus by a tissue-engineered construct. Many questions remain to be answered before the final goal, a tissue-engineered meniscus is available for clinical implementation. These questions are related to the selection of an optimal cell type, the source of the cells, the need to use growth factor(s) and the type of scaffold that can be used for stimulation of differentiation of cells into tissues with optimal phenotypes. Particularly in a loaded, highly complex environment of the knee, optimal mechanical properties of such a scaffold seem to be of utmost importance. With respect to cells, autologous meniscus cells seems the optimal cell source for tissue engineering of meniscus tissue, but their availability is limited. Therefore research should be stimulated to investigate the suitability of other cell sources for the creation of meniscus tissue. Bone marrow stroma cells could be useful since it is well known that they can differentiate into bone and cartilage cells. With respect to growth factors, TGF-beta could be a suitable growth factor to stimulate cells into a fibroblastic phenotype but the problems of TGF-beta introduced into a joint environment should then be solved. Polyurethane scaffolds with optimal mechanical properties and with optimal interconnective macro-porosity have been shown to facilitate ingrowth and differentiation of tissue into fibro-cartilage. However, even these materials cannot prevent cartilage degeneration in animal models. Surface modification and/or seeding of cells into the scaffolds before implantation may offer a solution for this problem in the future.This review focuses on a number of specific questions; what is the status of the development of procedures for lesion healing and how far are we from replacing the entire meniscus by a (tissue-engineered) prosthesis. Subquestions related to the type of scaffold used are: is the degree of tissue ingrowth and differentiation related to the initial mechanical properties and if so, what is the influence of those properties on the subsequent remodelling of the tissue into fibro-cartilage; what is the ideal pore geometry and what is the optimal degradation period to allow biological remodelling of the tissue in the scaffold. Finally, we will finish with our latest results of the effect of tear reconstruction and the insertion of prostheses on articular cartilage degradation.

Meniscal repair devices: a clinical and biomechanical literature review

PURPOSE

The development of new approaches to arthroscopic meniscal repair has spurred the concomitant publication of studies reviewing their use and biomechanical properties. The purpose of this article is to review both the devices and the literature surrounding their clinical and biomechanical properties.

TYPE OF STUDY

Literature review.

METHODS

Studies were initially gathered using a MEDLINE search, and additional information was found through cross references. We evaluate a series of studies comparing sutures, suture anchors, screws, staples, and a variety of other devices in terms of initial fixation strength, degradation profile, performance under cyclical loading, and clinical success.

RESULTS

In the traditional suture studies, vertical sutures are clearly superior to both horizontal sutures and knot-end techniques in terms of initial fixation strength and performance under cyclical loading. Unfortunately, multidevice studies have been less consistent and less conclusive. the Linvatec Biostinger, Smith & Nephew T-fix, and Bionx Meniscus Arrow have separately been shown to have superior initial fixation strength on par with suture techniques. After cyclical loading, horizontal sutures, vertical sutures, 16-mm Arrows, 13-mm Arrows, and the Smith & Nephew T-fix generally show higher fixation strengths. Only the Bionx Arrow, Linvatec Biostinger, and Clearfix Screw have been shown to retain their initial fixation strengths through four months of hydrolysis time.

CONCLUSIONS

Data suggest that the biomechanical performance of some devices is nearly equivalent to current suture techniques. Ultimately, the combination of a simplified surgical technique, high clinical healing rates (75%-92%), and relatively minor complications makes these devices attractive for properly indicated meniscal tears.

Biomechanical comparison of the FasT-Fix meniscal repair suture system with vertical mattress sutures and meniscus arrows

BACKGROUND

A meniscal repair technique that combines the strength of vertical mattress sutures and the decreased tissue morbidity of an all-inside technique would be advantageous.

HYPOTHESIS

The FasT-Fix Meniscal Repair Suture System will provide load at failure, stiffness, and displacement equivalent to that of vertical mattress sutures and superior to that of Meniscus Arrows.

STUDY DESIGN

In vitro biomechanical study.

METHODS

After repair of a 2-cm vertical longitudinal medial meniscal lesion, three groups of six human cadaveric knees were biomechanically tested in a random order on a servohydraulic device, and three groups of five specimens underwent cyclic loading.

RESULTS

Specimens repaired with Meniscus Arrows had reduced load at failure, stiffness, and displacement, but there were no differences between the FasT-Fix and vertical mattress suture methods. During cyclic loading, specimens repaired with two Meniscus Arrows failed before test completion, whereas specimens repaired with two vertical mattress sutures (6.0 +/- 3.7 mm) or with two FasT-Fix implants (5.1 +/- 1.4 mm) maintained fixation with comparable displacements.

CONCLUSIONS

The FasT-Fix provided load at failure, stiffness, and displacement comparable with that of vertical mattress sutures.

CLINICAL RELEVANCE

The results suggest that the FasT-Fix may be preferable to Meniscus Arrows for meniscal repair with minimal associated tissue morbidity.