Tissue fixation security in transosseous rotator cuff repairs: A mechanical comparison of simple versus mattress sutures

The primary purpose of this investigation was to compare tissue fixation security by simple sutures versus mattress sutures in transosseous rotator cuff repair. These two repair techniques were each performed in 17 human cadaver shoulders, with two bone tunnels being used for the repair by two simple sutures and two other bone tunnels being used for the repair by one mattress suture. The repairs were loaded to failure in a servohydraulic materials test system. Rotator cuff repair by simple sutures was found to be significantly stronger than repair by mattress sutures (P = .0007). The average ultimate load to failure for the simple suture construct (189.62 N) was 39.72% greater than that for the mattress suture construct (135.71 N). Most of the failures occurred by suture breakage at the knot. Load-sharing by multiple suture tails and multiple knots in the simple suture configuration likely contributed to its superior strength characteristics compared with the mattress suture configuration.     

Arthroscopic suture tying: A comparison of knot types and suture materials

Purpose: The purpose of this study was to determine the structural properties of 3 arthroscopically tied knots using 2 different suture materials: the French knot, the Duncan loop knot, and the original Revo knot. Type of Study: Cohort analytic study. Methods: The sutures used were No. 1 PDS II, an absorbent monofilament, and No. 1 Ethibond (Ethicon, Somerville, NJ), a braided nonabsorbent material. The resulting 6 suture-knot combinations were individually tested to failure in both open- and closed-loop configurations. Results: The French knot showed the greatest strength compared with the Duncan loop and the Revo knot with both No. 1 Ethibond and No. 1 PDS II sutures (P <.05). The No. 1 Ethibond exhibited higher initial stiffness than the No. 1 PDS II for all 3 knot types (P <.05). Results were similar for both open and closed-loop configurations. Also, the French knot failed predominantly by suture breakage instead of knot slippage for both suture materials. Conclusions: The results of this study suggest that, among the suture and knot combinations investigated in this study, the arthroscopic repair of musculoskeletal injuries should be performed using the French knot and No. 1 Ethibond suture.Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 17, No 4 (April), 2001: pp 348–352     

Cyclic testing of meniscal sutures.

Suturing the meniscus has become a standard procedure for repairable tears. Studies investigating the outcome of meniscal sutures report a considerable rate of failures. Regarding the indications, which have been extended to the avascular zones, and regarding some accelerated rehabilitation protocols, the need for further in vitro investigations has become obvious. The aim of this study was to compare different meniscal suture types (vertical and horizontal mattress sutures) and materials (absorbable monofilament PDS 2-0, and nonabsorbable braided Ethibond 2-0 [Ethicon, Somerville, NJ]) under standard and cyclic loading conditions. Testing was performed on medial porcine menisci. In group A, specimens were tested to failure at a cross-head speed of 50 mm/minute. In group B, cyclic testing (100 cycles) was performed first within different load intervals (5 to 20 N and 5 to 40 N). Finally, the specimens were loaded until failure. In both groups, the failure loads were recorded and the failure modes were analyzed. In group A, there was no difference between suture type or suture material, with a mean failure load of 60 N. The failure modes were significantly different for vertical (100% suture failure) and horizontal sutures (50% suture failure) (P <.0001). In group B, 13% of the sutures failed under cyclic loading (7 with 40-N load, 1 with 20-N load). The gap of the sutured tear that appeared within the first load cycles was broader in horizontal sutures (P <.001). During the first cycles, the thread cut through the meniscus tissue and disappeared from the surface (partial tissue failure). There was no difference according to suture material. The ultimate failure loads after cyclic loading did not differ from the values of group A. These results show that meniscal sutures may fail under repetitive loading conditions and that a gap appears between the meniscal margins within the first loading cycles irrespective of the suture type and suture material used. The appearance of the gap and suture disappearance on the meniscal surface because of partial tissue failures (which were more pronounced in the horizontal sutures) confirmed the superior resistance of meniscal tissue to vertical sutures.     

Bone plug versus suture fixation of the posterior horn in medial meniscalallograft transplantation: a biomechanical study

This study was performed to determine if a meniscal al- lograft with attached bone plug and suture offers superior ixation when compared to allograft afixed with suture alone through a bony tunnel. Seven pairs of human cadaver proximal tibia specimens were obtained. The specimens were then randomly assigned to either Group 1 (suture alone) or Group 2 (bone plug plus suture). All Group 1 specimens had the meniscus detached at the bony insertion of the anterior and posterior horns, with two No. 2 Ethibond sutures placed at the posterior root insertion. All Group 2 specimens had a posterior horn with a bone plug and two No. 2 Ethibond sutures. Both groups had their respective sutures passed through a 7 mm tibial tunnel and secured over a screw and post on the proximal tibia. The specimens were then loaded to failure. The mean failure load for Group 1 was 111.8 N (SD: 21 N) and for Group 2 was 112 N (SD: 32 N). Based on the Wilcoxon Rank-Sum analysis, the two groups were not signiicantly different. This study demonstrated no difference in the mean pullout strength of medial meniscal allograft posterior horn ixation between the two groups. This biome- chanical cadaveric study demonstrated that it may not be necessary to use an attached bone plug for medial meniscal transplant ixation, as using suture alone will sufice. The choice of using suture alone for the posterior horn meniscal attachment eases the technique of surgery when compared to using a bone plug plus suture.     

Comparison of the mechanical properties of different tension band materials and suture techniques

OBJECTIVES: This study determined the tensile properties of 18-gauge stainless steel wire, 5-mm woven polyester (Mersilene) tape, and multiple loop configurations of No. 5 braided polyester suture (Ethibond). DESIGN: Mechanical property testing. INTERVENTION: Single loops of stainless steel wire, Mersilene, and Ethibond were tested to determine their mechanical properties. Ethibond was tested with different numbers of loops and different knot configurations. MAIN OUTCOME MEASURES: Stiffness, load at failure, and elongation at failure. RESULTS: One loop of Mersilene and two loops of Ethibond had similar loads at failure, but the load at failure was significantly higher for stainless steel wire. Four loops of Ethibond withstood a similar failure load to stainless steel wire, but the failure load of the Ethibond suture was greater than the yield load of stainless steel wire. Stainless steel wire had a higher stiffness than both Ethibond and Mersilene. No difference was found in the failure load between different Ethibond knot configurations. The individually tied suture configuration resulted in a higher stiffness than the single-knot configuration. The elongation at failure was not statistically different among the different knot configurations and materials, with the exception of Mersilene tape. Mersilene tape demonstrated a significant increase in elongation at failure as compared to the other materials and knot configurations. CONCLUSION: It appears that multiple loops of Ethibond can substitute for stainless steel wire in situations where a compliant repair is suitable (support of a patellar tendon repair), but may not be satisfactory for rigid fixation (tension band fixation of a fracture). There appears to be no significant difference in strength but a small decrease in stiffness between tying multiple suture loops in one knot as opposed to individual knots.     

四种与Kessler相关的屈肌腱缝合方法的生物力学研究

目的 研究四种与Kessler相关的屈肌腱缝合方法 对肌腱修复抗张强度的影响.方法 采用新鲜猪后肢跖深屈肌腱,将40根肌腱分为4组,每组10根,横行切断,以Kessler法、DoubleKessler法、Running suture法、Kessler+Running suture法缝合.检测缝合后肌腱2mm间隙形成的负荷、最大抗张强度,采用ANOVA法进行统计分析.结果 对于肌腱的横断伤,最大抗张强度DoubleKessler法Kessler+Running suture法Kessler法Running suture法. 2mm间隙形成的负荷Kessler+Running suture法Double Kessler法Rumming suture法Kessler法.结论 肌腱横行损伤修复时,采用强生3-0编织缝合线,Kessler+Running suture法能够满足临床早期功能锻炼的强度要求.     

Effect of core suture technique and type on the gliding resistance during cyclic motion following flexor tendon repair: A cadaveric study

We investigated the effects of two suture techniques using three suture types in a human model in vitro. We obtained 60 flexor digitorum profundus (FDP) tendons from cadavers and measured the gliding resistance during 1,000 cycles of simulated flexion–extension motion and load to failure of six groups: the modified Kessler (MK) repair using 3‐0 coated, braided polyester (Ethibond, Ethicon, Somerville, NJ), 3‐0 coated, braided polyester/monofilament polyethylene composite (FiberWire®; Arthrex, Naples, FL), or 4‐0 FiberWire; and the Massachusetts General Hospital (MGH) repair using 3‐0 Ethibond, 3‐0 FiberWire, or 4‐0 FiberWire. The 3‐0 Ethibond MGH suture had significantly higher ultimate load to failure than the 3‐0 or 4‐0 FiberWire MK suture. The 3‐0 and 4‐0 FiberWire MGH sutures had significantly higher load to failure than the three MK groups. The gliding resistances of the three MGH groups were significantly higher than that of the three corresponding MK groups. The MGH repair had more gliding resistance than an MK repair, even when comparing large diameter suture in the MK repair with smaller diameter suture in the MGH repair. In this study, suture technique was more important in predicting repair load to failure and gliding resistance than the nature or caliber of the suture material that was used. © 2010 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 28:1475–1481, 2010     

Biomechanical testing of epitenon suture strength in Achilles tendon repairs

BACKGROUND: Recent evidence that early, active mobilization protocols after Achilles tendon repairs increase recovery speed and strength make operative repair strength critical to positive outcomes after Achilles tendon ruptures. While previous research has focused on core (tendon proper) repair techniques, no previous literature has reported testing of core repairs augmented with epitenon sutures, which have been shown to increase the strength of repairs of flexor tendons of the hand. METHODS: Five matched pairs of fresh frozen human Achilles tendons were tested with and without the addition of an epitenon suture to the core repair suture. All specimens were repaired using a No. 2 Ethibond Krakow locking loop core suture. The epitenon suture was added to one tendon randomly chosen from each pair, using a 4-0 nylon suture. All specimens were mounted on an MTS testing machine (MTS Systems Corp., Eden Prairie, MN) and loaded to failure, which was defined as a 1-cm gap formation. RESULTS: The addition of epitenon sutures significantly increased the force necessary to produce a 2-mm gap as compared to core sutures alone by 74%, and it increased the average load to failure by 119%. Also, initial tendon stiffness was 173% greater in tendons reinforced with epitenon sutures. CONCLUSIONS: This study demonstrates that greater resistance to gap formation, approximation of tissue ends, and tensile strength were achieved by the addition of an epitenon suture. Clinical relevance may improve healing by decreased gap formation at the repair site and a lower risk of adhesion formation.     

采用不同缝线及缝合位点缝合内侧半月板后根部损伤的生物力学研究

目的:比较不同高强度缝线及不同缝合位点缝合固定内侧半月板后根部损伤的生物力学特性。方法:取新鲜猪(雌性,月龄5～9个月,平均7个月)膝关节内侧半月板标本48个,采用Mason-Allen缝合方法建立实验模型。根据缝合位点不同随机分为红区固定组、红-白区固定组,每组24例。再根据固定材料不同将每组随机分为3个亚组,每组8例,分别采用Ethibond缝线、Ultrabraid缝线、FiberWire缝线固定。采用万能电磁力学试验机,先给予1 000次的循环载荷后行拔出试验,直至拔出失败;测量并计算标本最大失败载荷、失效载荷、拔出刚度及循环位移。结果:所有标本顺利完成生物力学测试。Ethibond缝线组失败模式均为缝线断裂。Ultrabraid缝线组失败模式:6例为缝线断裂,均属红区固定组;10例为缝线拔出,其中2例属红区固定组,8例属红-白区固定组。FiberWire缝线组失败模式均为缝线拔出。生物力学结果:(1)在缝线强度比较方面,最大失败载荷、失效载荷及拔出刚度:Ethibond缝线组Ultrabraid缝线组FiberWire缝线组,组间比较差异有统计学意义(P0.05);100、500、1 000次循环位移:Ethibond缝线组Ultrabraid缝线组FiberWire缝线组,组间比较差异有统计学意义(P0.05);表明FiberWire缝线强度最优,Ultrabraid缝线次之,Ethibond缝线最差。(2)在缝合位点比较方面,最大失败载荷、失效载荷及拔出刚度:红区固定组红-白区固定组,组间比较差异有统计学意义(P0.05);100、500、1 000次循环位移:红区固定组红-白区固定组,组间差异有统计学意义(P0.05),表明红区缝合强度优于红-白区缝合。结论:Mason-Allen缝合方法可有效固定内侧半月板后根部损伤并满足术后早期部分负重要求。术中采用FiberWire缝线并将缝合位点置于红区可获得更好的固定效果,有利于半月板愈合及功能恢复。     

In vitro cyclic tensile testing of combined peripheral and core flexor tenorrhaphy suture techniques

Early tenorrhaphy mobilization increases repair site strength and decreases adhesions. Preliminary unpublished data suggest that early active mobilization improves clinical outcome compared with traditional passive motion protocols. We loaded cadaver flexor profundus tendon repairs to 8.0 kg (78.4 N) for up to 5,000 cycles to simulate the loads and cycle number of our active flexor tendon rehabilitation protocol. 3-0 Ethibond (Ethicon, Somerville, NJ) and 6-0 Prolene (Surgi-pro; US Surgical, Norwalk, CT) were used for core and peripheral sutures, respectively. Four different groups were tested: 2-strand Tajima core suture with either a running interlocking (2R) or a Silfverski?ld cross-stitch (2S) peripheral suture and 4-strand Tajima plus horizontal mattress core suture with either a running interlocking (4R) or a Silfverski?ld peripheral suture (4S). Repairs failed in the suture midsubstance or at the knot. There was considerable variability within groups and no significant difference in the number of cycles to failure between the 2R, 4R, and 2S repairs, which failed after 2 +/- 2, 304 +/- 249, and 560 +/- 987 cycles, respectively. All 4S repairs were intact after 5,000 cycles. Our data suggest that flexor tenorrhaphy with the 4S repair can withstand the cyclic loads we estimate would be present during an active rehabilitation protocol.     

Der Einfluss verschiedener Nahtstärken auf das Verhalten von Meniskusnähten unter zyklischer Zugbelastung

The aim of this study was to analyze meniscal sutures under cyclic loading conditions for different suture types (vertical and horizontal mattress sutures) and suture materials (absorbable monofilament sutures: PDS 2-0; PDS-0, and PDS-1 USP). Testing was performed on medial porcine menisci, using a well-established biomechanical testing model with a complete longitudinal tear 3 mm from the periphery of the meniscus. Sixty specimens were used. One suture was tested at a time. During cyclic testing 100 load cycles were applied with a crosshead speed of 50 mm/min. Three different maximum loads (10 N, 20 N, and 40 N) were used. The preload was set at 5 N. After cyclic loading, the specimens were loaded until failure. During cyclic loading, a gap appeared between the two parts of the meniscus, and partial tissue failures were observed at the surface of the meniscus. Gapping was more marked with higher loads and with the weaker suture material (p < 0.001). Using PDS 0 and PDS 1 sutures, less partial tissue failures were observed compared to PDS 2-0 (p < 0.001). The ultimate failure loads after cyclic loading were higher with PDS-0 and PDS-1 sutures. With these suture materials vertical sutures were stronger than horizontal sutures (p < 0.05). Using PDS 2-0 this difference could not be found. These results show that the primary strength of meniscal sutures depends on the suture material. The frequency and the amount of gapping and partial tissue failures, which can be observed under cyclic loading, are less distinct with PDS-0 and PDS-1 compared to PDS 2-0. From a biomechanical point of view, PDS 0 and PDS 1 sutures are recommended for meniscal sutures to guarantee a high primary stability, a small amount of gapping, and few partial tissue failures.     

Failure characteristics of various arthroscopically tied knots

The current study evaluated multiple arthroscopic knot configurations and compared their properties with open, hand-tied square knots. This is an experimental study done on a material testing system. Number 2 Ethibond Extra and Number 1 Polydioxanone sutures were used. Four types of sliding knot configurations were tested: the Duncan loop, the Tennessee Slider, the Savoie-Modified Roeder, and the Lieurance-Modified Roeder. Two types of nonsliding knots were tested: the Revo knot and a knot consisting of alternating half-hitches tied with the Sixth Finger Knot Pusher. Ten knots were tied of each configuration, using strict arthroscopic technique. Each knot was backed-up with four half-hitches using post switching technique. Knots were tied around two rings and then transferred wet to a materials testing machine. The knots were tested until ultimate failure, with note of clinical failure at 3 mm. Ethibond suture using the Revo knot, the Lieurance-Modified Roeder knot, and the Savoie-Modified Roeder knot were similar in strength to the square knot with comparable failure modes. Polydioxanone suture was more variable; the Revo knot, the Savoie-Modified Roeder, the Tennessee Slider, and the Duncan loop were comparable with hand-tied square knots. All of the open and arthroscopic suture loops tested in this study failed by the suture loops expanding to greater than 3 mm before ultimate failure occurred. The surgeon choosing arthroscopic repair techniques should be aware of the differences in suture material and the variation in knot strength afforded by different knot configurations.     

Biomechanical investigations of different meniscal repair implants in comparison with horizontal sutures on human meniscus

Purpose: The use of biodegradable implants for arthroscopic repair of meniscal lesions is becoming increasingly popular. The aim of this study was to test the biomechanical stability and the mode of failure of these implants. Type of Study: Biomechanical testing study. Methods: Biomechanical investigations were performed on human menisci using 6 commonly used biodegradable implants for meniscal repair to compare them with horizontal mattress suture using 2/0 Ethibond (Ethicon, Norderstedt, Germany). Included in this study were the Meniscus Arrow (Bionx, Tampere, Finland), Dart (Arthrex, Naples, FL), Stinger (Linvatec, Largo, FL), Meniscal Screw (Innovasive, Marlborough, MA), T-Fix (Acufex, Mansfield, MA), and the Fastener (Mitek, Westwood, MA). The tests were carried out using a material testing machine at a loading rate of 10 N/second. The ultimate tension load (UTL), elongation, and stiffness were evaluated for each implant technique. Results: The highest UTL was shown by Ethibond (62 ± 7.91 N) and the T-Fix (51.35 ± 16.31 N), followed by the Fastener (32.67 ± 2.97 N). All other implants had a significantly lower UTL (P =.001). Less elongation under a load of 5 N was noted for Ethibond (0.64 ± 0.25 mm) and for T-Fix (0.43 ± 0.32 mm) compared with the other implants. The greatest elongation was found for the Fastener (2.239 ± 0.581 mm). The stiffness of the fixation was similar in all implants, except for the Dart and Fastener, which were significantly inferior (P <.05). Conclusions: All of the biodegradable implants had lower UTL than the suture techniques. Therefore, when using the implants, they should be inserted close together to provide sufficient stability. In cases of an extended lesion, there might even be an option to combine the implant and suturing techniques.Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 17, No 5 (May-June), 2001: pp 439–444     

Abrasion resistance of two types of nonabsorbable braided suture

Purpose: The purpose of this study was to compare the abrasion resistance of different types of non-absorbable braided sutures under varying in vitro conditions of cyclic loading. Type of Study: Biomechanical study. Methods: Two types of nonabsorbable braided sutures were used in this study, No. 2 Ethibond and No. 2 Fiberwire, combined with 5 different anchors: 5.0-mm Corkscrew anchor, 5.0-mm BioCorkscrew anchor, 3.0-mm BioFastak anchor, Panalok RC anchor, and 3.5-mm Panalok anchor. Twelve tests for each construct were performed. A custom-designed testing apparatus was constructed to evaluate the abrasion resistance of sutures through an anchor eyelet. The apparatus cycled the suture through the anchor eyelet at a rate of 84 revolutions per minute and a speed of 12.5 m/min. In addition to suture type, the effect of different suture-to-anchor angles and testing conditions (dry v wet testing) were evaluated. The number of cycles to failure and the mode of failure were recorded (suture breakage v eyelet breakage). Results: Results showed that under all testing conditions No. 2 Fiberwire displayed abrasion resistance superior to No. 2 Ethibond (P < .002 in all cases). The mean number of cycles to failure was 5 to 51 times greater when using No. 2 Fiberwire than when using No. 2 Ethibond. Altering the suture-to-anchor angle from 0° (in-line) to 45° decreased the abrasion resistance of both No. 2 Ethibond (69.8 cycles ± 26.5 cycles v 7.4 cycles ± 3.9 cycles; P < .000004) and No. 2 Fiberwire (918.3 cycles ± 417.4 cycles v 389.2 cycles ± 195.7 cycles; P = .001) when using the 5.0-mm Corkscrew anchor. Fiberwire performed equally well under both dry and wet conditions (P > .05) whereas Ethibond performed better under wet conditions (P = .0002) when using the 5.0-mm BioCorkscrew anchor. When using the Panalok RC anchor (mean failure, 11.2 cycles ± 1.3 cycles) or the 3.5-mm Panalok anchor (mean failure, 12.5 cycles ± 2.4 cycles), constructs failed at significantly lower cycles than other comparable anchor-suture constructs (P < .00007 in all cases). In addition, although the vast majority of failure modes for the other anchor-suture constructs was by suture breakage, the Panalok RC anchor and 3.5-mm Panalok anchor consistently failed by cutting of the suture through the biodegradable eyelet. Conclusions: (1) Suture abrasion differs according to the suture type, anchor type, and testing conditions. (2) No. 2 Fiberwire showed superior resistance to abrasion when compared with No. 2 Ethibond under all conditions tested in the study. (3) The abrasion resistance of No. 2 Fiberwire is sufficiently high to eliminate, clinically, the theoretical concerns over weakening of suture from the anchor eyelet. (4) Suture eyelets formed of biodegradable materials can fail at low numbers of cycles by cutting of the suture through the biodegradable eyelet during cyclic loading. Clinical Relevance: The study will help the surgeon to assess suture and suture anchor characteristics in order to optimize fixation of biologic tissues during surgical repair and reconstruction.     

Flexor tendon repair using shape memory alloy suture: a biomechanical evaluation

The purpose of the current study was to test in vitro a new shape memory alloy suture for flexor tendon repair. Forty fresh-frozen human anatomic flexor superficialis and profundus tendons were divided and repaired via the cruciate four-strand technique using one of two suture materials (the shape memory alloy suture and the 4-0 Ethibond suture). The forces required to cause a 1, 2, and 3 mm gap, ultimate load to failure, and repair stiffness were compared. Twenty specimens of each suture material also were tensile tested for load to failure, tensile strength, and elongation at failure. The shape memory alloy suture had a significantly higher mean resistance force to 1, 2, and 3 mm gap formation than the 4-0 Ethibond suture (47 N versus 31 N, 51 N versus 36 N, and 57 N versus 41 N, respectively). The shape memory alloy suture repair was 40% stronger than the 4-0 Ethibond suture (61.9 +/- 8.8 N versus 44.3 +/- 10.6 N). Repair with the shape memory alloy suture was significantly stiffer than repair with the 4-0 Ethibond suture (8.1 +/- 1.0 N/mm versus 6.1 +/- 0.9 N/mm). The load to failure and tensile strength of the shape memory alloy suture were significantly higher than that of the 4-0 Ethibond suture. The values of elongation for the two materials were not significantly different. The results of the current study suggest that the shape memory alloy suture may be superior to the 4-0 Ethibond suture in resisting gap formation in the range of forces generated in the early rehabilitation protocol and may be the future material of choice for tendon repairs.     

Biomechanical properties of four circumferential flexor tendon suture techniques

PURPOSE: We introduce 2 interlocking circumferential flexor tendon suture techniques: the interlocking cross-stitch and the interlocking horizontal mattress repair and biomechanically tested them against 2 commonly used methods. METHODS: Thirty-two deep digital flexor tendons harvested from sheep hindlimbs were transected sharply. These were repaired without a core suture using 4 different circumferential repair techniques: group 1, simple running; group 2, cross-stitch; group 3, interlocking cross-stitch; group 4, interlocking horizontal mattress. All tendons were tested to failure at a distraction rate of 20 mm/min. Load to 2-mm gap formation, stiffness, load to failure, and method of failure all were assessed. RESULTS: The mean load to 2-mm gap formation was 22.8, 20.7, 20.0, and 26.1 N for groups 1, 2, 3, and 4, respectively. The mean stiffness was 7.6, 8.1, 8.7, and 10.1 N/mm, and the mean load to failure was 30.9, 42.1, 49, and 52.9 N for groups 1, 2, 3, and 4, respectively. There was no statistically significant difference between groups 2 and 3. Group 4, however, was statistically better than the others in all measured parameters (except group 3 in load to failure). CONCLUSIONS: The interlocking horizontal mattress was the best performer overall, with statistically greater loads to failure, 2-mm gap formation, and stiffness. This technique could be considered for use in any patient likely to begin an early postoperative finger mobilization program.     

Meniscal repair devices

Summary: Meniscal repair devices not requiring accessory incisions are attractive. Many factors contribute to their clinical effectiveness including their biomechanical characteristics. This study compared several new meniscal repair devices with standard meniscal suture techniques. Using a porcine model, axis-of-insertion loads were applied to various meniscal sutures and repair devices. A single device or stitch was placed in a created meniscal tear and a load applied. Both loads and modes of failure were recorded. The load-to-failure data show stratification into 4 distinct statistical groups. Group A, 113 N for a double vertical stitch; group B, 80 N for a single vertical stitch; group C, 57 N for the BioStinger, 56 N for a horizontal mattress stitch, and 50 N for the T-Fix stitch; and group D, 33 N for the Meniscus Arrow (inserted by hand or gun), 32 N for the Clearfix screw, 31 N for the SDsorb staple, 30 N for the Mitek meniscal repair system, and 27 N for the Biomet staple. The failure mechanism varied. Sutures broke away from the knot. The Meniscus Arrow and BioStinger pulled through the inner rim with the crossbar intact. The Clearfix screw failed by multiple mechanisms, whereas 1 leg of the SDsorb staple always pulled out of the outer rim. The Mitek device usually failed by pullout from the inner rim. The Biomet staple always broke at the crosshead or just below it. Although the surgeon should be aware of the material properties of the repair technique chosen for a meniscal repair, this information is only an indication of device performance and may not correlate with clinical healing results.Arthroscopy: The Journal of Arthroscopic and Related surgery, Vol 16, No 6 (September), 2000: pp 613–618     

Cyclic loading of anchor-based rotator cuff repairs: Confirmation of the tension overload phenomenon and comparison of suture anchor fixation with transosseous fixation

Previous experimental studies of failure of rotator cuff repair have involved single pull to ultimate load. Such an experimental design does not represent the cyclic loading conditions experienced in vivo. We created 1 ×2 cm rotator cuff defects in 16 cadaver shoulders, repaired each defect with three MitekRC suture anchors (Mitek Surgical Products, Inc, Westwood, MA) using simple sutures of No. 2 Ethibond, and cyclically loaded the repairs by a servohydraulic materials test system actuator at physiological rates and loads (rate of 33 mm/s, load 180 N). A progressive gap was noted in each specimen, for a 100% rate of failure of the repairs. The central suture always failed first and by the largest magnitude, confirming tension overload centrally. One specimen exhibited combined bone and tendon failure, but the other 15 specimens failed through the tendon. Overall, the repairs failed to 5 mm and 10 mm at an average of 61 cycles and 285 cycles, respectively. Half the specimens were less than 45 years of age and had a 5-mm and 10-mm failure at an average of 107 and 478 cycles, respectively. The other half were over 45 years of age and failed to 5 mm and 10 mm at an average of 17 and 91 cycles, respectively, indicating more rapid failure of the rotator cuff tendons in the older group, and this was statistically significant (P ≤ .02). Comparison of suture anchor fixation in this study with transosseous bone tunnel fixation in a previous cyclic loading study at this institution indicates that bone fixation by suture anchors is significantly less prone to failure than bone fixation through bone tunnels (P = .0008). Changing the bone fixation from bone tunnels to suture anchors effectively transferred the weak link from bone to tendon.     

Failure of suture material at suture anchor eyelets

Purpose: In the repair of soft tissue to bone using suture anchors, failure of the suture material can occur at the anchor eyelet. This study examines the load strength at which suture material fails with different metallic suture anchor eyelets. Type of study: Biomechanical study. Methods: Suture material (Ethibond No. 2, Ethicon, Norderstedt, Germany) was pulled out from 22 metallic suture anchor models at 60 mm/min, and tensile load at failure and failure mode were recorded. Tests were performed either by simultaneous pulling on 2 suture limbs in 3 different directions (straight, at 45°, and at 45° rotated by 90° to the suture anchor axis) or by pulling on 1 suture limb while measuring the resulting force on the second limb. All tests were performed until suture failure. Pulling was performed in single tests on an Instron materials testing machine (High Wycombe, UK), with the anchors held by a vise. Results: In all cases, the suture failed at the anchor eyelet. Failure load at straight loading ranged from 116 ± 5 N to 226 ± 5 N and from 69 ± 5 N to 193 ± 7 N when loaded at an angle of 45°. The best results were found with the Statak 5.2-mm (Zimmer, Warsaw, IN): 177 N; Corkscrew 6.5-mm anchor (Arthrex, Naples, FL): 174 N; and PeBA 4.0-mm anchor (OBL Orthopaedic Biosystems, Scottsdale, AZ): 169 N. With each eyelet, sutures failed preferentially in 1 direction, depending on the presence of sharp edges. Conclusions: Suture material can be cut at suture anchor eyelets. Failure load depends on sharp edges on the eyelet and occurs at forces up to 73% below the breaking strength of the suture material on a smooth hook. Anchors with suture-protecting channels are particularly sensitive to the orientation in which the sutures are loaded.