Biomechanical comparison of suture anchor versus margin convergence plus suture anchor for rotator cuff repair

Objective: To evaluate results of margin convergence versus suture anchors in rotator cuff repair, and to determine which method is mechanically superior. Methods: Eighteen kangaroo shoulders were randomly divided into three groups (n = 6). A full thickness tendon defect 1.0 cm × 1.5 cm in size was created in the supraspinatus tendon at humeral insertion, simulating a massive rotator cuff tear. Three different techniques were employed for rotator cuff repair: (i) Mitek GII suture anchor alone (Group 1); (ii) margin convergence alone (Group 2); and (iii) margin convergence plus Mitek GII suture anchor (Group 3). Combined loads were applied to each specimen. After completion of cyclic loading, the construct was loaded to failure. ANOVA and LSD (Least Significant Difference) multiple comparisons of the means were applied to results. Results: Cyclic load testing showed progressive gap formation in each repaired specimen with increasing cycles. Group 1 reached 50% failure at an average of 34 cycles, Group 2 at 75 cycles and Group 3 at 73 cycles. There were significant difference between Groups 1 and 2, and Groups 1 and 3 (P ≤ 0.001). After 100 loading cycles, the average gap size was 6.8 mm, 6.1 mm and 4.7 mm in Groups 1, 2 and 3, respectively. There was a significant difference between Groups 1 and 3 (P ≤ 0.015). All specimens eventually reached failure. Conclusion: Rotator cuff repairs with margin convergence +/? suture anchor were far stronger than suture anchor alone, both in gap formation and ultimate failure load. However, progressive gap formation with cyclic loading seems inevitable after cuff repair, which may facilitate clinical understanding of the phenomena of re‐tear or residual defect.     

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.     

The failure mode of two reabsorbable fixation systems: Swivelock with Fibertape versus Bio-Corkscrew with Fiberwire in bovine rotator cuff

BackgroundDespite technical advances in rotator cuff surgery, recurrent or persistent defects in the repaired tendon continue to occur. The improved strength of sutures and suture anchors has shown that the most common site of failure is the suture–tendon interface. The purpose of this study was to compare two different types of repair under both cyclic and load-to-failure conditions. The hypothesis is that the use of a fixation system with knotless anchor and taped suture results in better biomechanical performance, under both cyclic and load-to-failure conditions.MethodsThirty bovine shoulder specimens were randomly assigned to two group tests: the Swivelock 5-mm anchor with Fibertape (Group A) and the Bio-Corkscrew 5 mm with Fiberwire (Group B). We simulated the reconstruction of a rotator cuff tear with a single-row technique, performing a tenodesis with types A and B fixation. Each specimen underwent cyclic testing from 5 to 30 N for 30 cycles, followed by load-to-failure testing, in order to calculate the ultimate failure load (UFL).ResultsLoad-to-failure tests revealed a significantly higher UFL in Group A than in Group B. Wire fixing failed at the anchor loop whereas tape fixing failed at the sutures, suture–tendon interface, and anchors. Cyclic testing revealed no significantly greater slippage between the two groups. Stiffness values were not statistically significantly different. In all cases, tendons remained intact until the end of the cyclic testing.ConclusionsThe tape structure is biomechanically stronger than the wire structure.     

Cyclic loading of rotator cuff repairs: A comparison of bioabsorbable tacks with metal suture anchors and transosseous sutures

Purpose: The purposes of the study were (1) to compare rotator cuff repair strengths after cyclic loading of 2 bioabsorbable nonsuture-based tack-type anchors, transosseous sutures, and a metal suture-based anchor, and (2) to correlate bone mineral density with mode of failure and cycles to failure. We hypothesized that specimens with a lower bone density would fail through bone at a lower number of cycles independent of the method of cuff fixation. Type of Study: Ex vivo biomechanical study. Methods: Standardized full-thickness rotator cuff defects were created in 30 fresh-frozen cadaveric shoulders that were randomized to 1 of 4 repair groups: transosseous sutures; Mitek Super suture anchors (Mitek Surgical Products, Westwood, MA); smooth bioabsorbable 8-mm Suretacs (Acufex, Smith & Nephew Endoscopy, Mansfield, MA); or spiked bioabsorbable 8-mm Suretacs (Acufex). All repairs were cyclically loaded from 10 to 180 N; the numbers of cycles to 50% (gap, 5 mm) and 100% (gap, 10 mm) failure were recorded. Results: In comparing the repair groups, we found only 1 significant difference: the number of cycles to 100% failure was significantly higher (P <.05) for the smooth bioabsorbable tack than for the transosseous suture group. There were no statistically significant (P ≤.05) differences in bone mineral densities with regard to each specimen’s mode of failure. Conclusions: Our results suggested that immediate postoperative fixation provided by bioabsorbable tacks was similar to that provided by Mitek anchors and more stable than that provided by transosseous sutures. Therefore, the immediate postoperative biomechanical strength of bioabsorbable tacks seems comparatively adequate for fixation of selected small rotator cuff tears. However, additional evaluation in an animal model to examine degradation characteristics and sustained strength of repair is recommended before clinical use.Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 17, No 4 (April), 2001: pp 360–364     

A biodegradable button to augment suture attachment in rotator cuff repair

Recent experimental studies suggest that the use of suture anchors for rotator cuff tear (RCT) repair transfers the "weak link" to the suture-tendon interface where failure occurs as the sutures cut through the tendon. The purpose of this study was to evaluate the effect of using a suture augmentation button on the fixation strength of rotator cuff tendon repair. A 1.5 cm by 2 cm defect was created in the supraspinatus tendon of seven cadaveric shoulder pairs and two suture anchors inserted in each humerus for suture attachment. For one of each pair, the defect was repaired with sutures placed in a horizontal mattress configuration. The other side was repaired with the sutures being passed through low profile, bioabsorbable buttons placed on the bursal tendon surface prior to knot tying. The supraspinatus tendon was cyclically loaded at a physiologic rate and load (33 mm/sec and 180 N, respectively). The number of loading cycles was recorded when the specimens developed 0.75 cm and 1.5 cm gaps at the repair site. The specimens were then tested to failure. Specimens in the unaugmented group developed 0.75 cm and 1.5 cm gaps at an average of 135 cycles and 362 cycles, respectively. The button augmented group developed these gaps at average of 420 cycles and 708 cycles, respectively. These differences were statistically significant (p < 0.05). The gaps progressively increased in all specimens, which eventually failed by suture cutting through tendon in all specimens. This study demonstrates that in vitro, suture augmentation with a low profile, bioabsorbable button provides significantly enhanced fixation when using suture anchors to repair torn rotator cuff tendon. This device may be a useful adjunct to current methods of rotator cuff repair.     

关节镜下双排固定治疗肩袖损伤

目的 观察关节镜下单排、双排固定治疗肩袖损伤的近期效果. 方法 对8例肩袖损伤采用单排固定,7例肩袖损伤进行双排固定,观察术后功能恢复情况,进行UCLA评分. 结果 双排固定术后恢复时间短,功能恢复快,UCLA评分明显优于单排固定.单排固定组2例锚钉拔出,行再次手术固定;2例术后锻炼时出现疼痛和术前症状,再次手术时发现缝合线断裂,予再次固定. 结论 肩袖损伤的关节镜下双排固定效果明显优于单排固定,双排固定不仅增加了固定强度,同时使肩袖肌腱断端与肱骨大结节的接触面积大大增加,更有利于腱骨愈合.     

Arthroscopic Rotator Cuff Repairs: An Anatomic and Biomechanical Rationale for Different Suture-Anchor Repair Configurations

The goal of rotator cuff repairs is to achieve high initial fixation strength, minimize gap formation, maintain mechanical stability under cyclic loading, and optimize the biology of the tendon-bone interface until the cuff heals biologically to the bone. We have seen an evolution in our approaches to fixing rotator cuff tears from open to mini-open to all arthroscopic. In our arthroscopic techniques, we have also seen a change in the types of anchors and sutures we use and our repair techniques including an evolution in techniques that include single row, double row, and, most recently, transosseous equivalent fixation. Single-row repairs are least successful in restoring the footprint of the rotator cuff and are most susceptible to gap formation. Double-row repairs have an improved load to failure and minimal gap formation. Transosseous equivalent repairs have the highest ultimate load and resistance to shear and rotational forces and the lowest gap formation. This review will discuss the anatomy and biomechanics of a normal rotator cuff, the biomechanical factors that play a role in rotator cuff repairs, the initial fixation repair mechanics, and finally propose an algorithm for rotator cuff fixation based on tissue quality and tear configuration.     

Mode of failure for rotator cuff repair with suture anchors identified at revision surgery

Rotator cuff tears are a common cause of shoulder pain and dysfunction. After surgical repair, there is a significant re-tear rate (25%-90%). The aim of this study was to determine the primary mode of mechanical failure for rotator cuffs repaired with suture anchors at the time of revision rotator cuff repair. We prospectively followed 342 consecutive torn rotator cuffs, repaired by a single surgeon using suture anchors and a mattress-suturing configuration. Of those shoulders, 21 (6%) subsequently underwent a revision rotator cuff repair by the original surgeon, and 1 underwent a second revision repair. Intraoperative findings, including the mode of failure, were systematically recorded at revision surgery and compared with the findings at the primary repair. In addition, 81 primary rotator cuff repairs had a radiographic and fluoroscopic evaluation at a mean of 37 weeks after repair to assess for any loosening or migration of the anchors. At revision rotator cuff repair, the predominant mode of failure was tendon pulling through sutures (19/22 shoulders) (P <.001). Two recurrent tears occurred in a new location adjacent to the previous repair, and one anchor was found loose in the supraspinatus tendon. The mean size of the rotator cuff tear was larger at the revision surgery (P =.043), the tendon quality ranked poorer (P =.013), and the tendon mobility decreased (P =.002), as compared with the index procedure. The radiographs and fluoroscopic examination showed that all 335 anchors in 81 patients were in bone. Rotator cuff repairs with suture anchors that underwent revision surgery failed mechanically by three mechanisms, the most common of which was tendon pulling through sutures. This suggests that the weak link in rotator cuff repairs with suture anchors and horizontal mattress sutures, as determined at revision surgery, is the tendon-suture interface.     

Mechanical strength of arthroscopic rotator cuff repair techniques: an in vitro study

BACKGROUND: Retears after rotator cuff repairs occur relatively frequently and may compromise the functional result. The goal of this study was to analyze the mechanical properties following arthroscopic techniques for rotator cuff repair and to evaluate possible alternative techniques. METHODS: In the first part, five different bone anchors (the Revo screw; Mitek Rotator Cuff anchor, 5.0-mm Statak, PANALOK RC absorbable anchor, and 5.0-mm Bio-Statak) were tested in vitro under cyclic loading on five pairs of cadaveric shoulders. Then five types of arthroscopic tendon suturing instruments were tested on rotator cuff tendons. Finally, the arthroscopically performed mattress and modified Mason-Allen stitches, fixed with either the Revo screw or the Bio-Statak, were evaluated on ten pairs of human cadaveric shoulders. RESULTS: The holding strengths of the various anchors were similar, ranging from 130 to 180 N, and approximated the holding strength of knotted number-2 suture materials. The fixation of the tested anchors yielded comparable values of stiffness except for one anchor, which showed significantly greater subsidence under cyclic load (p = 0.003). All tested, commercially available arthroscopic suturing devices were unsuitable for performing a modified Mason-Allen stitch on normal supraspinatus tendons. Modification of a commercially available suture punch with a longer needle allowed us to consistently perform a modified Mason-Allen stitch. The modified Mason-Allen stitch, which has shown favorable mechanical properties in open repairs of the rotator cuff, was not found to be stronger than the mattress stitch when performed arthroscopically and used with bone anchors. When the modified Mason-Allen stitch was fixed to one anchor, it was even weaker than a mattress stitch repaired with another anchor (168 versus 228 N). Unequal loading of the two suture branches due to the more rigid modified Mason-Allen stitch may be the reason for this difference. CONCLUSIONS: Arthroscopic techniques for rotator cuff repair with use of the mattress stitch and bone anchors allow for a relatively solid fixation. The holding strength is not improved with use of the modified Mason-Allen stitch. Although a direct comparison with previous in vitro studies is not possible, the holding strength of open fixation techniques seems to be stronger. If rotator cuffs are subjected to high postoperative loading, open repair might be preferred to reduce the risk of a retear, until stronger arthroscopic fixation techniques are developed.     

Anatomic Reduction and Next-Generation Fixation Constructs for Arthroscopic Repair of Crescent,L-Shaped,and U-Shaped Rotator Cuff Tears

Emerging techniques and instrumentation have allowed orthopaedic surgeons to achieve rotator cuff repair through an all-arthroscopic technique. The most critical steps in rotator cuff repair consist of proper identification of the cuff tear pattern and anatomic restoration of the torn tendon footprint. With anatomic reduction of the rotator cuff tendons, a sound fixation construct can help restore rotator cuff contact pressure and kinematics, allowing for decreased repair tension and optimal healing potential. We provide surgical methods to recognize tear patterns and present a repair construct that will restore the anatomic footprint of the torn rotator cuff tendon. The key, initial maneuver to restore the anatomic footprint of the cuff includes placement of a suture anchor at the anterolateral corner for L-shaped tears and at the posterolateral corner for reverse L–shaped and U-shaped tears. After insertion of the medial-row anchors, the tendon stitches should be planned by use of a grasper to hold the tendon in a reduced position and guide location of the stitch. The lateral row with suture bridge can be visualized, and the final repair construct should produce an anatomic restoration of the rotator cuff footprint.     

A Modified Suture-Bridge Technique for a Marginal Dog-Ear Deformity Caused During Rotator Cuff Repair

Recently, the suture-bridge technique was found to maximize the utility of a single-row construct by using the suture limbs from the medial mattress sutures to bridge and compress the repaired tendon. However, the formation of marginal dog-ear deformities at a repaired rotator cuff is not uncommon with the suture-bridge technique. If a dog-ear deformity is observed at the margin after completion of the rotator cuff repair, the detached marginal cuff is pierced via a suture hook. One strand of the uncut suture in the lateral row is transported through the deformed cuff. A nonsliding knot is seated on top of the detached cuff and presses this area of soft tissue firmly onto the bone. If necessary, these steps are repeated for the other side of the detached rotator cuff. After completion of the rotator cuff repair, a “zigzag” pattern of compression of the cuff against the bone footprint without detachment of the rotator cuff is observed. After repair of the rotator cuff tear via the suture-bridge technique, the benefit of our simple technique for treating a marginal detached cuff is that the footprint contact area of the rotator cuff is restored completely, without the need for additional suture anchors.     

Rotator cuff repair with a novel mesh suture: An ex vivo assessment of mechanical properties

Surgical repair is a common treatment for rotator cuff tear; however, the retear rate is high. A high degree of suture repair strength is important to ensure rotator cuff integrity for healing. The purpose of this study was to compare the mechanical performance of rotator cuffs repaired with a mesh suture versus traditional polydioxanone suture II and FiberWire sutures in a canine in vitro model. Seventy‐two canine shoulders were harvested. An infraspinatus tendon tear was created in each shoulder. Two suture techniques—simple interrupted sutures and two‐row suture bridge—were used to reconnect the infraspinatus tendon to the greater tuberosity, using three different suture types: Mesh suture, polydioxanone suture II, or FiberWire. Shoulders were loaded to failure under displacement control at a rate of 20 mm/min. Failure load was compared between suture types and techniques. Ultimate failure load was significantly higher in the specimens repaired with mesh suture than with polydioxanone suture II or FiberWire, regardless of suture technique. There was no significant difference in stiffness among the six groups, with the exception that FiberWire repairs were stiffer than polydioxanone suture II repairs with the simple interrupted technique. All specimens failed by suture pull‐out from the tendon. Based on our biomechanical findings, rotator cuff repair with the mesh suture might provide superior initial strength against failure compared with the traditional polydioxanone suture II or FiberWire sutures. Use of the mesh suture may provide increased initial fixation strength and decrease gap formation, which could result in improved healing and lower re‐tear rates following rotator cuff repair. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:987–992, 2018.

     

An in-vitro study of rotator cuff tear and repair kinematics using single- and double-row suture anchor fixation

Purpose:

Double-row suture anchor fixation of the rotator cuff was developed to reduce repair failure rates. The purpose of this study was to determine the effects of simulated rotator cuff tears and subsequent repairs using single- and double-row suture anchor fixation on three-dimensional shoulder kinematics. It was hypothesized that both single- and double-row repairs would be effective in restoring active intact kinematics of the shoulder.

Materials and Methods:

Sixteen fresh-frozen cadaveric shoulder specimens (eight matched pairs) were tested using a custom loading apparatus designed to simulate unconstrained motion of the shoulder. In each specimen, the rotator cuff was sectioned to create a medium-sized (2 cm) tear. Within each pair, one specimen was randomized to a single-row suture anchor repair, while the contralateral side underwent a double-row suture anchor repair. Joint kinematics were recorded for intact, torn, and repaired scenarios using an electromagnetic tracking device.

Results:

Active kinematics confirmed that a medium-sized rotator cuff tear affected glenohumeral kinematics when compared to the intact state. Single- and double-row suture anchor repairs restored the kinematics of the intact specimen.

Conclusions:

This study illustrates the effects of medium-sized rotator cuff tears and their repairs on active glenohumeral kinematics. No significant difference (P ≥ 0.10) was found between the kinematics of single- and double-row techniques in medium-sized rotator cuff repairs.

Clinical Relevance:

Determining the relative effects of single- and double-row suture anchor repairs of the rotator cuff will allow physicians to be better equipped to treat patients with rotator cuff disease.     

The Double-Pulley Technique for Double-Row Rotator Cuff Repair

In an effort to maximize the area of footprint coverage, we developed the “double-pulley technique” for double-row rotator cuff repairs. Two suture anchors are inserted at the articular margin of the greater tuberosity (one anterior and one posterior). All 4 suture strands from each anchor are passed through a single medial point on the torn cuff. In this way, the 4 suture strands from the anteromedial anchor pass through 1 point in the cuff and the 4 strands from the posteromedial anchor pass through a different point in the cuff. A suture strand from 1 anchor is tied extracorporeally to a suture strand of the same color from the other anchor. The other ends of those 2 strands are then pulled, thereby delivering this extracorporeal knot into the joint and over the medial footprint. These 2 free suture strands are then tied together as a static knot. The procedure is repeated with the other sutures. This technique creates a double mattress suture medially, which compresses the intervening tendon bridge against its bone bed. We call this procedure the double-pulley technique because it uses the anchor eyelets as pulleys to deliver the extracorporeal knot into the shoulder. After the lateral row repair is performed, the rotator cuff footprint will be completely reconstituted.     

A biomechanical comparison of single and double-row fixation in arthroscopic rotator cuff repair

BACKGROUND: The optimal method for arthroscopic rotator cuff repair is not yet known. The hypothesis of the present study was that a double-row repair would demonstrate superior static and cyclic mechanical behavior when compared with a single-row repair. The specific aims were to measure gap formation at the bone-tendon interface under static creep loading and the ultimate strength and mode of failure of both methods of repair under cyclic loading. METHODS: A standardized tear of the supraspinatus tendon was created in sixteen fresh cadaveric shoulders. Arthroscopic rotator cuff repairs were performed with use of either a double-row technique (eight specimens) or a single-row technique (eight specimens) with nonabsorbable sutures that were double-loaded on a titanium suture anchor. The repairs were loaded statically for one hour, and the gap formation was measured. Cyclic loading to failure was then performed. RESULTS: Gap formation during static loading was significantly greater in the single-row group than in the double-row group (mean and standard deviation, 5.0 +/- 1.2 mm compared with 3.8 +/- 1.4 mm; p < 0.05). Under cyclic loading, the double-row repairs failed at a mean of 320 +/- 96.9 N whereas the single-row repairs failed at a mean of 224 +/- 147.9 N (p = 0.058). Three single-row repairs and three double-row repairs failed as a result of suture cut-through. Four single-row repairs and one double-row repair failed as a result of anchor or suture failure. The remaining five repairs did not fail, and a midsubstance tear of the tendon occurred. CONCLUSIONS: Although more technically demanding, the double-row technique demonstrates superior resistance to gap formation under static loading as compared with the single-row technique. CLINICAL RELEVANCE: A double-row reconstruction of the supraspinatus tendon insertion may provide a more reliable construct than a single-row repair and could be used as an alternative to open reconstruction for the treatment of isolated tears.     

A Novel Transosseous Button Technique for Rotator Cuff Repair

In an attempt to maximize stability by improving the lateral footprint compression of our repair in rotator cuff tears, we have been using a rotator cuff button (Arthrex, Naples, FL) passed through a transosseous tunnel as an anchor for our transosseous sutures. Our new innovation is to pass a rotator cuff button fully loaded with 4 strands around the central post, with 2 leading strands and 2 trailing strands on either end, through our transosseous tunnel. In this way, we can use the 4 central strands through our tunnel to obtain 2 good mattress sutures as a primary repair and the peripheral 4 strands passed around the lateral humerus as over sew mattress sutures to obtain good compression of the lateral tendon and so improve the footprint area. A double row equivalent is achieved. This technique has a good primary hold in the form of a device with proven history and avoids multiple anchors in the lateral humerus. Because it uses only a single fixation device, it is also significantly more economical. Theoretical risks to the axillary nerve or with osteoporosis have not been seen in practice. Tensioning the repair with suture passage through transosseous tunnels is readily achieved.     

Biomechanical evaluation of arthroscopic rotator cuff repairs: double-row compared with single-row fixation

BACKGROUND: Recent studies have shown that arthroscopic rotator cuff repairs can have higher rates of failure than do open repairs. Current methods of rotator cuff repair have been limited to single-row fixation of simple and horizontal stitches, which is very different from open repairs. The objective of this study was to compare the initial cyclic loading and load-to-failure properties of double-row fixation with those of three commonly used single-row techniques. METHODS: Ten paired human supraspinatus tendons were split in half, yielding four tendons per cadaver. The bone mineral content at the greater tuberosity was assessed. Four stitch configurations (two-simple, massive cuff, arthroscopic Mason-Allen, and double-row fixation) were randomized and tested on each set of tendons. Specimens were cyclically loaded between 5 and 100 N at 0.25 Hz for fifty cycles and then loaded to failure under displacement control at 1 mm/sec. Conditioning elongation, peak-to-peak elongation, ultimate tensile load, and stiffness were measured with use of a three-dimensional tracking system and compared, and the failure type (suture or anchor pull-out) was recorded. RESULTS: No significant differences were found among the stitches with respect to conditioning elongation. The mean peak-to-peak elongation (and standard error of the mean) was significantly lower for the massive cuff (1.1 +/- 0.1 mm) and double-row stitches (1.1 +/- 0.1 mm) than for the arthroscopic Mason-Allen stitch (1.5 +/- 0.2 mm) (p < 0.05). The ultimate tensile load was significantly higher for double-row fixation (287 +/- 24 N) than for all of the single-row fixations (p < 0.05). Additionally, the massive cuff stitch (250 +/- 21 N) was found to have a significantly higher ultimate tensile load than the two-simple (191 +/- 18 N) and arthroscopic Mason-Allen (212 +/- 21 N) stitches (p < 0.05). No significant differences in stiffness were found among the stitches. Failure mechanisms were similar for all stitches. Rotator cuff repairs in the anterior half of the greater tuberosity had a significantly lower peak-to-peak elongation and higher ultimate tensile strength than did repairs on the posterior half. CONCLUSIONS: In this in vitro cadaver study, double-row fixation had a significantly higher ultimate tensile load than the three types of single-row fixation stitches. Of the single-row fixations, the massive cuff stitch had cyclic and load-to-failure characteristics similar to the double-row fixation. Anterior repairs of the supraspinatus tendon had significantly stronger biomechanical behavior than posterior repairs.     

Transosseous Fixation in Insertional Achilles Tendonitis

The surgical approach of severe insertional Achilles tendonitis involves debridement, repair, and reattachment. Previously described techniques for bone–tendon reattachment involved the use of suture anchors in the sparsely trabeculated calcaneus. The following technique tip is a reintroduction of bicortical transosseous fixation previously used in rotator cuff repairs. Bone tunnels are a viable option in the treatment of insertional Achilles tendonitis; however, additional research is necessary to validate its efficacy in this application.     

Suture anchor fixation strength in osteopenic versus non-osteopenic bone for rotator cuff repair

Introduction

Rotator cuff tears are increasing with age. Does osteopenic bone have an influence on the pullout strength of suture anchors?

Materials and methods

SPIRALOK 5.0 mm (DePuy Mitek), Super Revo 5 mm and UltraSorb (both ConMed Linvatec) suture anchors were tested in six osteopenic and six healthy human cadaveric humeri. Incremental cyclic loading was performed. The ultimate failure load, anchor displacement, and the mode of failure were recorded.

Results

In the non-osteopenic bone group, the absorbable SPIRALOK 5.0 mm achieved a significantly better pullout strength (274 N ± 29 N, mean ± SD) than the titanium anchor Super Revo 5 mm (188 N ± 34 N, mean ± SD), and the tilting anchor UltraSorb (192 N ± 34 N, mean ± SD). In the osteopenic bone group no significant difference in the pullout strength was found. The failure mechanisms, such as anchor pullout, rupture at eyelet, suture breakage and breakage of eyelet, varied between the anchors.

Conclusion

The present study demonstrates that, in osteopenic bone, absorbable suture anchors do not have lower pullout strengths than metal anchors. In normal bone, the bioabsorbable anchor in this study even outperformed the non-absorbable anchor.

     

Current Biomechanical Concepts for Rotator Cuff Repair

For the past few decades, the repair of rotator cuff tears has evolved significantly with advances in arthroscopy techniques, suture anchors and instrumentation. From the biomechanical perspective, the focus in arthroscopic repair has been on increasing fixation strength and restoration of the footprint contact characteristics to provide early rehabilitation and improve healing. To accomplish these objectives, various repair strategies and construct configurations have been developed for rotator cuff repair with the understanding that many factors contribute to the structural integrity of the repaired construct. These include repaired rotator cuff tendon-footprint motion, increased tendon-footprint contact area and pressure, and tissue quality of tendon and bone. In addition, the healing response may be compromised by intrinsic factors such as decreased vascularity, hypoxia, and fibrocartilaginous changes or aforementioned extrinsic compression factors. Furthermore, it is well documented that torn rotator cuff muscles have a tendency to atrophy and become subject to fatty infiltration which may affect the longevity of the repair. Despite all the aforementioned factors, initial fixation strength is an essential consideration in optimizing rotator cuff repair. Therefore, numerous biomechanical studies have focused on elucidating the strongest devices, knots, and repair configurations to improve contact characteristics for rotator cuff repair. In this review, the biomechanical concepts behind current rotator cuff repair techniques will be reviewed and discussed.