Biomechanical evaluation of a new technique for rotator cuff repair

BACKGROUND: In recent studies, investigators have used a cyclic loading model to investigate the efficacy of rotator cuff fixation modalities. HYPOTHESIS: A bioabsorbable poly-D-lactic acid screw and toothed washer implant will provide more stable fixation of rotator cuff repairs than standard suture anchor techniques. STUDY DESIGN: Controlled laboratory study. METHODS: Forty bovine shoulders (ages 3 to 6 months) had 1 x 2 cm defects created in the infraspinatus tendon. There were five repair groups (eight specimens per group) consisting of either two screw and washer implants or two suture anchors. Four suture techniques were tested: single-loaded anchors with simple sutures, double-loaded anchors with simple sutures, single-loaded anchors with horizontal mattress sutures, or single-loaded anchors with modified Mason-Allen sutures. Repairs were loaded at 5-second cycles from 10 to 180 N with use of a hydraulic testing machine. The number of cycles to gap formation of 5 and 10 mm was recorded. RESULTS: Gap formation of 5 and 10 mm occurred significantly later for the screw repair group than for any of the suture anchor groups. There was no significant difference between suture groups. CONCLUSIONS: The bioabsorbable screw and washer provided more stable fixation than suture anchor techniques under isometric cyclic loading conditions. Clinical Relevance: This is a time-zero study of implant performance. The results indicate that the implant may decrease clinical failures in the early postoperative period under standard rehabilitation protocols.     

Failure mode of suture anchors as a function of insertion depth

BACKGROUND: Surgeons can control not only the angle but also the depth of suture anchor placement during arthroscopic rotator cuff repair, although the tendency may be to place suture anchors on the deep side to avoid damage from prominent anchor eyelets. However, little information is available regarding possible effects of suture anchor depth on construct failure mechanisms. HYPOTHESIS: Anchor depth affects the mode of suture failure with physiologically relevant cyclic loads. STUDY DESIGN: Controlled laboratory study. METHODS: Metallic screw-in suture anchors loaded with No. 2 braided polyester sutures were inserted into the bovine infra-spinatus footprint with the eyelet proud, standard, or deep. Sutures were hand tied to create a closed loop. Constructs were cyclically loaded from 10 to 90 N and, if still intact at 500 cycles, taken to ultimate failure (maximum load). RESULTS: When clinical failure was defined as greater than 3-mm construct elongation, anchors placed with the eyelet deep experienced statistically earlier clinical failure via cutting of the suture through the bone (P < .02). However, anchors placed at this level did not experience catastrophic failure during cyclic loading. The standard and proud anchors experienced 3 mm of elongation at a greater number of cycles, but the suture material degraded at the anchor eyelet, and a majority of these constructs broke during cyclic physiologic loading. At failure testing, the deep anchors had a significantly increased failure load (164 N) compared to standard (133 N) (P < .04) and proud (113 N) anchors (P < .005). CONCLUSION: Varying the depth of suture anchor insertion changes the mechanical properties and mode of failure of suture anchor constructs. CLINICAL RELEVANCE: Surgeons should be aware of the effects of suture anchor depth and abrasive eyelet wear on construct failure during arthroscopic rotator cuff repair.     

Cyclic loading comparison of Bio-SutureTak-#2 FiberWire and Bio Mini-Revo-#2 Hi-Fi suture anchor-sutures in cadaveric scapulae

This study compared tap-in Bio-SutureTak suture anchor-#2 FiberWire suture (Group 1) and screw-in Bio Mini-Revo suture anchor-#2 Hi-Fi suture (Group 2) fixation in the glenoid region of interest for Bankart repair, in addition to evaluation of isolated suture loop biomechanical properties under progressive incremental cyclic loads. With knowledge of glenoid apparent bone mineral density (BMD), implant preparation and fit characteristics, and following application of a light manual tensile load, the primary investigator scored each specimen for perceived within group biomechanical test performance using a 0–10 point modified visual analog scale. After scoring, 12 paired constructs were placed in a servo hydraulic device clamp, preloaded to 25 N, and cycled between 25 and 50 Hz with a 25 N load increase every 25 cycles. Group 2 withstood greater load (104.1 ± 56 vs. 70 ± 36.9 N, P = 0.04) and displaced more at failure (13 ± 4.5 vs. 8.6 ± 3.3 mm, P = 0.04). All Group 1 specimens failed prior to reaching 150 N, whereas 25% of Group 2 specimens (n = 3) failed at 200 N. All specimens failed by anchor pullout except for three Group 2 specimens that failed by eyelet breakage at 200 N. Isolated suture testing revealed that Group 1 sutures displaced less at each cyclic load (P = 0.028) and withstood greater failure loads (P = 0.028) than that of Group 2 sutures. Group 2 constructs displayed moderately strong relationships between perceived within group biomechanical test performance and ultimate load (r ² = 0.55) and displacement at failure (r ² = 0.67). Group 1 did not display significant relationships. Similar biomechanical performance between 50 and 125 N, greater load at failure, and superior biomechanical test prediction accuracy suggest that the screw-in type Bio Mini-Revo suture anchor-#2 Hi-Fi suture combination may be preferred for Bankart lesion repair in low apparent BMD glenoid processes. The #2 Hi-Fi suture, however, allowed significantly greater displacement than the #2 FiberWire suture at each progressive cyclic load interval.     

Biomechanical comparison of a single-row versus double-row suture anchor technique for rotator cuff repair

BACKGROUND: Reestablishment of the native footprint during rotator cuff repair has been suggested as an important criterion for optimizing healing potential and fixation strength. HYPOTHESIS: A double-row rotator cuff footprint repair will demonstrate superior biomechanical properties compared with a single-row repair. STUDY DESIGN: Controlled laboratory study. METHODS: In 9 matched pairs of fresh-frozen cadaveric shoulders, the supraspinatus tendon from 1 shoulder was repaired with a double-row suture anchor technique: 2 medial anchors with horizontal mattress sutures and 2 lateral anchors with simple sutures. The tendon from the contralateral shoulder was repaired using a single lateral row of 2 anchors with simple sutures. Each specimen underwent cyclic loading from 10 to 180 N for 200 cycles, followed by tensile testing to failure. Gap formation and strain over the footprint area were measured using a video digitizing system; stiffness and failure load were determined from testing machine data. RESULTS: Gap formation for the double-row repair was significantly smaller (P < .05) when compared with the single-row repair for the first cycle (1.67 +/- 0.75 mm vs 3.10 +/- 1.67 mm, respectively) and the last cycle (3.58 +/- 2.59 mm vs 7.64 +/- 3.74 mm, respectively). The initial strain over the footprint area for the double-row repair was nearly one third (P < .05) the strain of the single-row repair. Adding a medial row of anchors increased the stiffness of the repair by 46% and the ultimate failure load by 48% (P < .05). CONCLUSION: Footprint reconstruction of the rotator cuff using a double-row repair improved initial strength and stiffness and decreased gap formation and strain over the footprint when compared with a single-row repair. CLINICAL RELEVANCE: To achieve maximal initial fixation strength and minimal gap formation for rotator cuff repair, reconstructing the footprint attachment with 2 rows of suture anchors should be considered.     

Effect of cyclic loading on new polyblend suture coupled with different anchors

BACKGROUND: Secure tendon-to-bone fixation is essential for successful rotator cuff repair. Biomechanical properties of devices used in rotator cuff repair should be better understood. PURPOSE: To evaluate the response to incremental cyclic loading of 6 different anchor-suture complexes commonly used in rotator cuff repair. STUDY DESIGN: Controlled laboratory study. METHODS: Two absorbable anchors 5 mm and 6.5 mm in diameter and 1 metallic anchor, coupled with Ethibond or FiberWire, were tested on 5 pairs of fresh-frozen human cadaveric shoulders. An incremental cyclic load was applied until failure using a Zwich-Roell Z010 electromechanical testing machine. The ultimate failure load and mode of failure were recorded. An analysis of variance model was used for statistical analysis. RESULTS: The FiberWire suture coupled with both absorbable and metallic anchors provided statistically significantly stronger fixation. However, although the metallic anchors in most cases failed because of slippage of the anchor, absorbable anchors failed because of rupture of the eyelet. CONCLUSIONS: The FiberWire seems to increase the strength of fixation devices under cyclic load using both absorbable and metallic anchors, with relevant differences in failure mode (slippage of the metallic anchor and eyelet failure in the absorbable anchor). CLINICAL RELEVANCE: Use of the FiberWire suture might change the mode of failure of the suture-anchor complexes.     

Arthroscopic rotator cuff repair: clinical outcome of 607 patients

The purpose of this study was to evaluate the clinical results of rotator cuff tendon tears treated by arthroscopic repair with suture anchors. This prospective study included a cohort of 607 consecutive patients who underwent arthroscopic rotator cuff repair surgery. Most patients had a single-row type of repair using metal anchors. All patients were independently assessed pre- and post-operatively utilizing the UCLA (University of California at Los Angeles) scoring system with a minimum of 1 year follow-up. Demographic and operative details were noted; including the patient age, workers compensation status, tear size, type of repair performed, and concomitant procedures. The median UCLA score improved from 13 (0–28) to 35 (8–35) with a median follow-up time of 46 months (12–105), P < 0.001. The majority of the patients (529) achieved good to excellent results. The results were found to be independent of age, workers compensation status, tear size, type of repair performed and concomitant procedures. In conclusion, arthroscopic rotator cuff repair, using metal anchors with dual sutures, in a single row, utilizing margin convergence sutures and performing concomitant procedures when necessary, gave satisfactory results in 87% of patients.     

Biomechanische Aspekte der Rotatorenmanschettennaht: Einfluss von Nahtmaterial,Knotentechnik und Nahttechnik auf die Primärstabilität

BackgroundThe treatment of Rotator cuff (RC) tears has made significant chances in the last decades. Due to arthroscopic procedures new material and technologies have been developed. Up to now, attention was focused mainly on the development of material with higher mechanical strength, stronger suture material, or improving of suturing and knotting. The present study focusses on all different aspects together which influence the biomechanical stability of rotator cuff tear reconstructions.Materials and MethodsDiverse kinds of suture anchors (different designs and materials) and transosseous sutures were tested biomechanically in human humeral specimen. Arthroscopic sliding and nonsliding-nodes were tested with conventional (Ethibond and PDS) and new UHMWPE sutures for biomechanical features. Additionally we tested three arthroscopic suture techniques (single-, matress-, arthroscopic Mason Allen- stitch) with above mentioned materials in human RC tendons. All tests were performed under cyclic loading on the Zwick universal Testing machine. The maximum failure rate, the clinical failure rate at 3 mm irreversible expension and the failure mechanism were evaluated.ResultsBetween the different suture anchors were found significantly differences only in healthy human humeral specimen. In osteoporotic bone all different suture anchors were comparable with failure values less than 200 N. Subcortical fixed suture anchors tend to have a higher stability than in cancellous bone fixed suture anchors. Transosseos sutures showed no benefits in osteoporotic bone. With up to 300 N the UHMWPE sutures had a significantly higher strength than Ethibond / PDS sutures. Though, depending on the node type, even UHMWPE sutures showed a relevant elongation at values between 100-200 N. The lowest biomechanical strength showed the tendon-suture construct. Even though the Mason Allen stitch with UHMWPE sutures showed the highest stability (>200 N) clinical failure appeared at about 100 N. The weakest link in the failure of RC repair seems to be the suture-tendon interface. Even when using UHMWPE sutures and a biomechanical stable suture technique clinical failure was observed at approx. 100 N.ConclusionsThese results suggest that the development of suture anchors with rising diameter seems to be irrelevant. Rather, the technical development should focus on small anchors with a subcortical fixation and therefore better biomechanical stability. Especially in revision cases this seems to be relevant. Post-operative treatment should be moderate because clinical failure can appear from only 100 N of load.Level of evidenceLevel IV.     

Pullout strength of meniscal repair after cyclic loading: comparison of vertical, horizontal, and oblique suture techniques

This in vitro biomechanical study with cyclic loading compared the pullout strength of vertical, horizontal, and oblique sutures used for meniscal lesion repair. Following repair of vertical longitudinal lesions created in bovine medial menisci, three groups of seven specimens (vertical, horizontal, and oblique sutures) underwent cyclic loading in a randomized test order (5 mm/min, cycling between 5 and 50 N at 1 Hz for 100 cycles) prior to load to failure testing (5 mm/min). Displacement did not differ between groups during cyclic or load to failure testing. Construct stiffness during cyclic testing was superior for the oblique suture (6.9 ± 1.5 N/mm, P = 0.007) and the vertical suture (6.4 ± 7 N/mm, P = 0.03) groups compared to the horizontal suture group (4.4 ± 0.52 N/mm). The oblique suture (171.9 ± 25.9 N, P < 0.0001) and the vertical suture (145.9 ± 32.3 N, P = 0.001) groups displayed superior load at failure compared to the horizontal suture group (88.8 ± 8.2 N). Construct stiffness during load to failure testing did not differ between groups. Suture rupture was the failure mode for all specimens of the oblique suture group. Suture rupture was the failure mode for 57% (4/7) of the vertical suture group with the remaining specimens (3/7, 43%) failing from intact suture pullout through meniscal tissue. All horizontal suture group specimens failed by intact suture pulling through meniscal tissue. With comparable stiffness during cyclic testing, comparable load at failure as vertical sutures, and less evidence of intact suture pullout through the meniscus, an oblique suture technique may combine the beneficial characteristics of vertical (superior biomechanical strength) and horizontal (ease of application, longer sutures with a tendency to cover a larger meniscal tissue area) suture-repair techniques.     

Pullout strength of suture anchors in comparison with transosseous sutures for rotator cuff repair

Suture anchors are increasingly gaining importance in rotator cuff surgery. This means they will be gradually replacing transosseous sutures. The purpose of this study was to compare the stability of transosseous sutures with different suture anchors with regard to their pullout strength depending on bone density. By means of bone densitometry (CT scans), two groups of human humeral head specimens were determined: a healthy and a osteopenic bone group. Following anchor systems were being tested: SPIRALOK™ 5.0 mm (resorbable, DePuy Mitek), Super Revo 5 mm (titanium, Linvatec), UltraSorb (resorbable, Linvatec) and the double U-sutures with Orthocord™ USP 2 (partly resorbable, DePuy Mitek) and Ethibond Excel 2 (non-resorbable, Ethicon). The suture anchors/double U-sutures were inserted in the greater tuberosity 12 times. An electromechanical testing machine was used for cyclic loading with power increasing in stages. We recorded the ultimate failure loads, the system displacements and the modes of failure. The suture anchors tended to bring about higher ultimate failure loads than the transosseous double U-sutures. This difference was significant in the comparison of the Ethibond suture and the SPIRALOK 5.0 mm—both in healthy and osteopenic bone. Both the suture materials and the SPIRALOK 5.0 mm showed a significant difference in pullout strength on either healthy or osteopenic bone; the titanium anchor SuperRevo 5 mm and the tilting anchor UltraSorb did not show any significant difference in healthy or osteopenic bone. There was no significant difference concerning system displacement (healthy and osteopenic bone) between the five anchor systems tested. The pullout strength of transosseous sutures is neither on healthy nor on osteopenic bone higher than that of suture anchors. Therefore, even osteopenic bone does not constitute a valid reason for the surgeon to perform open surgery by means of transosseous sutures. The choice of sutures in osteopenic bone is of little consequence anyway since it is mostly the bone itself which is the limiting factor.     

Biomechanical characteristics of single-row repair in comparison to double-row repair with consideration of the suture configuration and suture material

The aim of the study was to evaluate the time zero mechanical properties of single- versus double-row configuration for rotator cuff repair in an animal model with consideration of the stitch technique and suture material. Thirty-two fresh-frozen sheep shoulders were randomly assigned to four repair groups: suture anchor single-row repair coupled with (1) braided, nonabsorbable polyester suture sized USP No. 2 (SRAE) or (2) braided polyblend polyethylene suture sized No. 2 (SRAH). The double-row repair was coupled with (3) USP No. 2 (DRAE) or (4) braided polyblend polyethylene suture No. 2 (DRAH). Arthroscopic Mason–Allen stitches were used (single-row) and combined with medial horizontal mattress stitches (double-row). Shoulders were cyclically loaded from 10 to 180 N. Displacement to gap formation of 5- and 10-mm at the repair site, cycles to failure, and the mode of failure were determined. The ultimate tensile strength was verified in specimens that resisted to 3,000 cycles. DRAE and DRAH had a lower frequency of 5- (P = 0.135) and 10-mm gap formation (P = 0.135). All DRAE and DRAH resisted 3,000 cycles while only three SRAE and one SRAH resisted 3,000 cycles (P < 0.001). The ultimate tensile strength in double-row specimens was significantly higher than in others (P < 0.001). There was no significant variation in using different suture material (P > 0.05). Double-row suture anchor repair with arthroscopic Mason–Allen/medial mattress stitches provides initial strength superior to single-row repair with arthroscopic Mason–Allen stitches under isometric cyclic loading as well as under ultimate loading conditions. Our results support the concept of double-row fixation with arthroscopic Mason–Allen/medial mattress stitches in rotator cuff tears with improvement of initial fixation strength and ultimate tensile load. Use of new polyblend polyethylene suture material seems not to increase the initial biomechanical aspects of the repair construct.     

The use of suture anchors in repair of the ruptured patellar tendon: a biomechanical study

BACKGROUND: Rupture of the patellar tendon is a disabling injury that usually requires surgical treatment. The standard method of repair involves placing suture loops through transpatellar tunnels. The use of suture anchors in patellar tendon repair has not been previously described. HYPOTHESIS: No difference exists in the amount of gap formation during cyclic loading or in ultimate load-to-failure strength between repairs performed with anchors and those performed with 2 types of transpatellar sutures. STUDY DESIGN: Controlled laboratory study. METHODS: Six matched pairs of cadaveric knees were tested in a custom biomechanical apparatus based on an established model. Repairs were performed using either suture anchors with No. 2 FiberWire or transpatellar suture tunnels using 2 different types of suture-No. 5 Ethibond and No. 2 FiberWire. Gap formation across the repair site during 250 cycles of extension as well as ramp-up load to failure were measured for each repair. RESULTS: The mean total gap formation across the repair site at 250 cycles was 4.1 +/- 1.9 mm for the suture anchor group, 6.7 +/- 1.8 mm for the FiberWire tunnel group, and 8.5 +/- 2.7 mm for the Ethibond tunnel group. Mean load to failure was 779 +/- 183 N, 730 +/- 83 N, and 763 +/- 231 N, respectively. CONCLUSION: Significantly less gap formation throughout 250 cycles (P = .009) and no difference in load to failure occurred with patellar tendon repairs performed with suture anchors as compared with repairs performed with transpatellar tunnels. CLINICAL RELEVANCE: The newly described method, using suture anchors for repair of patellar tendon ruptures, may be clinically equal or superior to the established method of using transpatellar tunnels.     

A biomechanical study of four different meniscal repair systems,comparing pull-out strengths and gapping under cyclic loading

Most studies comparing the biomechanical properties of different meniscal repair systems have simply investigated load to failure. Meniscal tissue is highly anisotropic, and far weaker under tension in the radial direction. Radially oriented loading to failure may not therefore be the most physiologically relevant in vitro test for repair of circumferential tears, and determining gapping across repair sites under cyclical loading at lower loads may be of greater importance. Using bovine menisci, vertical circumferential incisions were repaired using a simple vertical 2-0 PDS suture, Meniscal Arrow, Meniscal Fastener or T-Fix. Repairs were tested by simple loading to failure in a materials testing machine, and by cyclic loading between 5 and 10 N for 25 cycles. Initial gapping across the repairs was measured using a digital micrometer, and the increase in gapping under cyclic loading measured using a Differential Voltage Reluctance Transducer. The mean loads to failure for each of the repair groups were: sutures 72.7 N, Arrows 34.2 N, Fasteners 40.8 N and T-Fix 49.1 N. The load to failure was significantly greater with sutures than with Arrows or Fasteners. The mean gapping across the repairs for each of the repair groups after 25 loading cycles were: sutures 3.29 mm, Arrows 2.18 mm, Fasteners 3.99 mm and T-Fix 3.47 mm. The mean gapping was significantly less with Arrows than with Sutures, Fasteners or T-Fix. These results confirm that meniscal repair by suturing gives the highest load to failure, but show that Arrows give superior hold under lower loads, with the least gapping across repairs under cyclic loading of the four methods tested.     

Tendon-to-bone pressure distributions at a repaired rotator cuff footprint using transosseous suture and suture anchor fixation techniques

BACKGROUND: Interface contact pressure between the tendon and bone has been shown to influence healing. This study evaluates the interface pressure of the rotator cuff tendon to the greater tuberosity for different rotator cuff repair techniques. HYPOTHESIS: The transosseous tunnel rotator cuff repair technique provides larger pressure distributions over a defined insertion footprint than do suture anchor techniques. STUDY DESIGN: Controlled laboratory study. METHODS: Simulated rotator cuff tears over a 1 x 2-cm infraspinatus insertion footprint were created in 25 bovine shoulders. A transosseous tunnel simple suture technique (n = 8), suture anchor simple technique (n = 9), and suture anchor mattress technique (n = 8) were used for repair. Pressurized contact areas and mean pressures of the repaired tendon against the tuberosity were determined using pressure-sensitive film placed between the tendon and the tuberosity. RESULTS: The mean contact area between the tendon and tuberosity insertion footprint was significantly greater for the transosseous technique (67.7 +/- 5.8 mm(2)) compared with the suture anchor simple (34.1 +/- 9.4 mm(2)) and suture anchor mattress (26.0 +/- 5.3 mm(2)) techniques (P < .05). The mean interface pressure exerted over the footprint by the tendon was also greater for the transosseous technique (0.32 +/- 0.05 MPa) compared with the suture anchor simple (0.26 +/- 0.04 MPa) and suture anchor mattress (0.24 +/- 0.02 MPa) techniques (P < .05). CONCLUSION: The transosseous tunnel rotator cuff repair technique creates significantly more contact and greater overall pressure distribution over a defined footprint when compared with suture anchor techniques. CLINICAL RELEVANCE: Stronger and faster rotator cuff healing may be expected when beneficial pressure distributions exist between the repaired rotator cuff and its insertion footprint. Tendon-to-tuberosity pressure and contact characteristics should be considered in the development of improved open and arthroscopic rotator cuff repair techniques.     

Mechanical comparison of meniscal repair devices with mattress suture devices in vitro

We report the load to failure in tensile testing of the MaxFire™ meniscal repair system (Biomet Inc, Warsaw, IN) and compare it to other current meniscal repair devices and mattress suture techniques. After creating a longitudinal tear in 42 one-year-old bovine menisci, 7 specimen groups defined by the meniscal repair device, suture, and/or mattress technique used for meniscal repair were randomly established: (Group 1: Fiberwire™ vertical mattress (VM), Group 2: Fiberwire™ horizontal mattress (HM), Group 3: FasT-Fix™ VM, Group 4: FasT-Fix™ HM, Group 5: RapidLoc™, Group 6: MaxFire™ VM, Group 7: MaxFire™ HM). After completing the repairs, the meniscal specimens were cyclically pre-loaded before load to failure testing was performed. The mean load to failure for each group was: Fiberwire VM (185 ± 41 N), Fiberwire HM (183 ± 36 N), FasT-Fix VM (125 ± 8 N), FasT-Fix HM (107 ± 29 N), RapidLoc (70 ± 12 N), MaxFire VM (145 ± 44 N), MaxFire HM (139 ± 50 N). An analysis of variance demonstrated a significant difference in the mean load to failure (F = 8.31 P < 0.01). Statistically significant differences were seen between both Fiberwire groups verses FasT-Fix HM and Rapid-Loc (P < 0.05). Three modes of failure were observed: suture breakage (17/42, 40.5%), tissue failure (18/42, 42.9%), and knot failure (7/42, 16.7%). 2-0 Fiberwire™ VM and HM repairs had the highest load to failure of all groups tested. The load to failure for the MaxFire™ meniscal repair system is comparable to other available all-inside meniscal repair systems.     

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.     

Is the transglenoid suture technique recommendable for recurrent shoulder dislocation? A minimum 5-year follow-up in 59 non-athletic shoulders

The aim of this retrospective study is to compare the clinical outcomes following arthroscopic Bankart repair employing the transglenoid technique versus suture anchors in non-athletic shoulders of patients 30 years or older at the time of surgery. Fifty-nine consecutive patients who were available for a minimum of 5 years follow-up after arthroscopic Bankart repair were included. The transglenoid technique was employed in 27 patients whose age and follow-up period were 37 years (range 30–58) and 82 (range 61–109) months. Suture anchor was used in 32 patients whose age and follow-up period were 38 years (range 30–62) and 72 months (range 65–89). The Rowe scores of the transglenoid and suture anchor groups were 90 (range 35–100) and 90 (range 35–100), respectively, and there was no statistically significant difference between the two groups (p > 0.05). The Constant score of both groups was 92 (range 64–100) and 95 (range 62–100) without a significant difference (p > 0.05). Moreover, there were no significant differences between the recurrence rates (7%-transglenoid, 6%-suture anchor) (p > 0.05) and positive apprehension signs (7%-transglenoid, 3%-suture anchor) (p > 0.05). In non-athletes over 30-years-old, the results of the transglenoid technique in arthroscopic Bankart repair were comparable to those of the suture anchor. We suggest that the transglenoid technique is a viable alternative for older, non-athletic shoulder if the suture anchors are not available.     

Anchor design and bone mineral density affect the pull-out strength of suture anchors in rotator cuff repair: which anchors are best to use in patients with low bone quality?

BACKGROUND: Different metal and biodegradable suture anchors are available for rotator cuff repair. Poor bone quality may result in anchor loosening and tendon rerupture. HYPOTHESES: Higher bone mineral density is associated with higher pull-out strength of suture anchors. Depending on anchor placement, pull-out strengths of anchors are different within the greater tuberosity. STUDY DESIGN: Cadaveric biomechanical study. METHODS: Trabecular and cortical bone mineral densities were determined for different regions within the greater tuberosity. Metal screw-type and biodegradable hook-type anchors were cyclically loaded. RESULTS: Mean failure load of metal and biodegradable anchors was 273 N and 162 N, respectively, for the proximal part (P < .01) and 184 N and 112 N, respectively, for the distal part (P < .01). Both types of anchors showed higher failure loads in the proximal-anterior and -middle parts of the greater tuberosity than in the distal part (P < .01). A significant positive correlation was found between cortical bone mineral density and failure load of metal anchors (P < .01). CONCLUSION: Bone quality, anchor type, and anchor placement have a significant impact on anchor failure loads. CLINICAL RELEVANCE: Suture anchors should be placed in the proximal-anterior and -middle parts of the greater tuberosity. In the distal parts, biodegradable hook-like anchors should be used with caution.     

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.     

Rotator cuff repair. A biomechanical comparison of three techniques

BACKGROUND: The most common complication of rotator cuff repair is structural failure at the repair site. A single-layer repair does not adequately reproduce the anatomic insertion and may not optimize fixation strength. HYPOTHESIS: A double-layer rotator cuff repair will have greater initial fixation strength than a single-layer repair. STUDY DESIGN: Controlled laboratory study. METHODS: Twelve fresh-frozen matched pairs of cadaveric shoulders were repaired by using dual-site fixation with both suture anchors and transosseous tunnels on one side (technique 1). Fixation was achieved by using suture anchors with horizontal mattress sutures and bone tunnels with modified Mason-Allen sutures. Half of the contralateral matched shoulders underwent fixation with suture anchors and simple sutures to simulate commonly used arthroscopic methods (technique 2) and, in the rest, fixation was achieved by using transosseous tunnels and modified Mason-Allen sutures (technique 3). Repaired specimens then underwent cyclic loading at physiologic rates and loads. The number of cycles to failure, which was defined as a 1-cm gap at the repair site, was then recorded. An arbitrary cut-off point of 5000 cycles was chosen. RESULTS: The mean number of cycles to failure with technique 1 (3694 +/- 1980 cycles) was significantly greater than that with either technique 2 (1414 +/- 1888 cycles) or technique 3 (528 +/- 683 cycles). Failure was predominantly through bone. CONCLUSIONS: The initial fixation strength of our double-layer repair exceeds that of isolated single-layer repairs with either suture anchors or transosseous tunnels.     

Arthroscopic single-row versus double-row suture anchor rotator cuff repair

BACKGROUND: Recurrent defects after open and arthroscopic rotator cuff repair are common. Double-row repair techniques may improve initial fixation and quality of rotator cuff repair. PURPOSE: To evaluate the load to failure, cyclic displacement, and anatomical footprint of 4 arthroscopic rotator cuff repair techniques. HYPOTHESIS: Double-row suture anchor repair would have superior structural properties and would create a larger footprint compared to single-row repair. STUDY DESIGN: Controlled laboratory study. METHODS: Twenty fresh-frozen cadaveric shoulders were randomly assigned to 4 arthroscopic repair techniques. The repair was performed as either a single-row technique or 1 of 3 double-row techniques: diamond, mattress double anchor, or modified mattress double anchor. Angle of loading, anchor type, bone mineral density, anchor distribution, angle of anchor insertion, arthroscopic technique, and suture type and size were all controlled. Footprint length and width were quantified before and after repair. Displacement with cyclic loading and load to failure were determined. RESULTS: There were no differences in load to failure and displacement with cyclic loading between the single-row repair and each double-row repair. All repair groups demonstrated load to failure greater than 250 N. A significantly greater supraspinatus footprint width was seen with double-row techniques compared to single-row repair. CONCLUSIONS: The single-row repair technique was similar to the double-row techniques in load to failure, cyclic displacement, and gap formation. The double-row anchor repairs consistently restored a larger footprint than did the single-row method. CLINICAL RELEVANCE: The arthroscopic techniques studied have strong structural properties that approached the reported performance of open repair techniques. Double-row techniques provide a larger footprint width; although not addressed by this study, such a factor may improve the biological quality of repair.