Rotator cuff repair with bioabsorbable screws: An in vivo and ex vivo investigation

Purpose: The purpose of this study was to evaluate in vivo the clinical outcomes of rotator cuff repairs with bioabsorbable screws compared with metal suture anchors, and to compare the ex vivo initial load to failure of rotator cuff repairs using 3 different bioabsorbable screws, suture anchors, and transosseous sutures. Type of Study: In vivo clinical outcomes investigation, and ex vivo biomechanical study. Methods: Three cohorts of patients with rotator cuff tears that measured less than 4 cm², were sequentially repaired with Mitek Rotator Cuff QuickAnchors (Mitek Surgical Products, Norwood, MA) (n = 9), Arthrex Headed Bio-Corkscrews (n = 9) (Arthrex, Naples, FL), and Mitek Rotator Cuff QuickAnchors (n = 9). Patients were systematically assessed with a specific shoulder questionnaire and 23 shoulder tests performed preoperatively and at 1 and 6 weeks, 3 and 6 months, and 1 year postoperatively. A correlative ex vivo biomechanical study was performed on 53 ovine shoulders to evaluate the initial failure load properties of bioabsorbable screws compared with fixation with suture anchors and transosseous sutures. Results: In the in vivo portion of the study, the cohort treated with the Headed Bio-Corkscrew demonstrated no improvement on any measured parameter until 1-year after rotator cuff repair. In contrast, shoulders repaired with Mitek Rotator Cuff QuickAnchors demonstrated improved overall shoulder function as early as 6 weeks postoperatively (P =.002), had a better constant score at 1-year after repair (88 ± 9 v 73 ± 17; P =.016), and a lower rate of revision rotator cuff repair (P =.029). In the ex vivo portion of the study, the bioabsorbable headed screws, Headed Bio-Corkscrew (100 ± 30 N) and BioTwist (76 ± 35 N), had inferior initial failure load properties compared with suture anchors (140 ± 36 N) and transosseous sutures (147 ± 68 N). In contrast, the BioCuff (190 ± 56 N), a bioabsorbable implant that used a screw and serrated washer design, had equivalent initial failure load properties as the suture repairs. Conclusions: This investigation had poorer early outcomes, a lower shoulder functional score 1-year after repair, and a higher rate of repeat surgery in patients who had their rotator cuff repaired with a bioabsorbable screw than in patients who had their shoulders repaired with a standard metal suture anchor. Furthermore, the biomechanical testing demonstrated a lower tensile load to failure in the tendons repaired with a simple screw design compared to suture anchors with a mattress stitch. Of note, the implant that used a screw and washer design demonstrated a greater ability to resist initial tensile load.Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 19, No 3 (March), 2003: pp 239–248     

Über die Primärfestigkeit konventioneller und alternativer Nahttechniken der RotatorenmanschetteEine biomechanische Untersuchung

The aim of this biomechanical study was to evaluate rotator cuff repair strength using different suture anchor techniques compared to conventional repair, taking into consideration the native strength of the supraspinatus tendon. Therefore, a defined defect of the supraspinatus was created in 50 freshly frozen cadaver specimen (group size n = 10; median age at death: 56 years). Five methods were employed for cuff repair: standard transosseous suture, modified transosseous suture with patch augmentation and three suture anchors (Acufex Wedge TAG, Acufex Rod TAG und Mitek GII). The maximum tensile load of the five techniques was: standard transosseous suture, 410 N; modified transosseous suture, 552 N; Wedge TAG, 207 N; Rod TAG, 217 N; Mitek GII, 186 N. The difference between the suture anchor and standard techniques were highly significant (P < 0.001). In this series, the Mitek Gll anchor showed the lowest anchor dislocation rate at 3% (n = 1). The Wedge TAG system had a dislocation rate of 27% (n = 8) and the Rod TAG system 43% (n = 13). Suture anchor techniques revealed about 20%, the standard technique 34% and its modification 60% of the hypothetically calculated native tendon strength. Compared to conventional transosseous suture techniques, the use of the suture anchors tested in this series does not significantly increase the primary fixation strength of rotator cuff repair. The metallic implant with two barbs (Mitek GII) seems to be superior to the polyacetal anchors when inserted into the spongiform bone of the greater tubercle. The considerably weaker repair strength needs to be taken into consideration in postoperative patient rehabilitation, especially after the use of suture anchors.     

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.     

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.     

Primary fixation strength of rotator cuff repair techniques: a comparative study

Purpose:The goal of the study was to compare the primary fixation strength of transosseous suture, suture anchor, and hybrid repair techniques for rotator cuff repair.Type of Study:Animal model experiment.Methods:Thirty-two sheep shoulders were divided into 4 homogeneous groups, according to bone density and tendon dimensions. Infraspinatus tendons were transected from their insertions and reattached using 4 different techniques. Group 1 was repaired with a single Mason-Allen stitch and 2 transosseous tunnels for each end of the suture, knotted on the lateral cortex of proximal humerus; group 2 was repaired with double Mason-Allen stitches and 2 transosseous tunnels; group 3 was repaired with 2 Corkscrews (Arthrex, Germany); and group 4 was repaired with 2 Corkscrews combined with a single Mason-Allen transosseous suture. All specimens were tested for their fixation strengths with a material testing system.Results:The mode of failure in group 1 was mainly suture breakage. In groups 3 and 4, the tendons pulled out from the sutures. In group 2, sutures broke the bony bridge between the 2 tunnels. The mean load to failure value was 160.31 ± 34.59 N in group 1, 199.36 ± 11.73 N in group 2, 108.32 ± 15.98 N in group 3, and 214.24 ± 28.52 N in group 4. Anchor fixation was significantly weaker compared with other groups (P <.001). Combination of a transosseous suture and anchor fixation (group 4) was significantly stronger than the single transosseous suture (group 1) and double anchor techniques (group 3) (P <.001).Conclusions:Hybrid technique was the strongest among the tested rotator cuff repair techniques. With the addition of one transosseous suture to two anchors, the strength of the repair could be doubled.     

In vitro comparison of standard and knotless metal suture anchors

Purpose: Clinical experience after failed Knotless suture anchor (Mitek, Westwood, MA) fixations suggested that the Knotless anchor provides considerably less fixation stability than a standard metal anchor. The purpose of this study was to analyze soft tissue fixation to bone comparing a standard and a Knotless metal suture anchor. Type of Study: In vitro study. Methods: The Mitek GII and Mitek Knotless suture anchors were tested on 7 human cadaveric fresh-frozen glenoids. The anchors were inserted into the glenoid rims, and the sutures of the anchors were fixed to a metal hook attached to the cross-head of a testing machine. Cyclic loading was performed. The gap formation between the metal hook and the glenoid rim, the ultimate failure loads and the modes of failure were determined. Results: The mean gap formation was significantly greater for the Knotless anchor (3.8 ± 1.4 mm) than for the GII anchor (2.4 ± 0.5 mm) after 25 cycles with 50 N repeated load (P = .04). The largest gap of a Knotless fixation was 5.3 mm compared with 3.0 mm for the GII. The ultimate failure load was not significantly different for the Knotless anchor (179 N) and for the GII anchor (129 N). Both anchors failed by either rupture of the suture material or by pullout of the anchors. Conclusions: The GII anchor allows significantly less displacement than the Knotless anchor. Ultimate tensile strength and mode of failure are similar. Greater displacement results in larger gap formation between the soft tissue and the bone. This might weaken and jeopardize the repair. Clincial Relevance: If reattached soft tissues are subjected to postoperative loading, gap formation may result when using the Knotless anchor. For these conditions, suture fixation with knots may be used instead.     

Disintegration of an absorbable rotator cuff anchor six weeks after implantation

Rotator cuff failure by suture-bone or suture anchor pull-out, suture breakage, knot slippage, and tendon pull-out are well described. I report a case of early disintegration of a bioabsorbable suture anchor. A 77-year-old woman underwent arthroscopic rotator cuff repair. On suspecting failure, the repair was repeated 40 days later. Arthroscopy revealed disintegration of the suture loop from the anchor. Open rotator cuff repair was then performed with transosseous suture and metallic anchors.     

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.     

Arthroscopic bone tunnel augmentation for rotator cuff repair

Transosseous repair of the rotator cuff has been shown to recreate the anatomic rotator cuff footprint in a secure and cost-efficient manner. However, the potential for sutures cutting through bone remains a concern with this strategy. Devices have been used successfully during open transosseous rotator cuff repair to augment the bone tunnels, potentially avoiding suture cut-out through the weak bone of the greater tuberosity. Recently, arthroscopic transosseous fixation of rotator cuff tears has become an alternative to arthroscopic suture anchor and open transosseous techniques. This method is expected to have the same potential pitfalls at the bone-suture interface as the open technique. The authors describe a technique for rotator cuff repair using a secure method of arthroscopic bone tunnel augmentation.     

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.     

Editorial Commentary: “Knot” Less Strength at Half the Cost—Is It Time to Abandon Medial Row Anchors in Shoulder Double-Row Rotator Cuff Repair?

Transosseous equivalent rotator cuff repair is an expensive construct that has demonstrated biomechanical superiority when compared with other rotator cuff repair techniques. A novel transosseous knotless repair that substitutes medial row anchors for a transosseous tunnel rivals the biomechanical advantages of transosseous equivalent rotator cuff repair at half the cost and with reduced dependence on bone quality. Surgeons should carefully consider if “knotless transosseous is more.”     

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 testing of a new knotless suture anchor compared with established anchors for rotator cuff repair

Various suture anchors are available for rotator cuff repair. For arthroscopic application, a knotless anchor was developed to simplify the intra-operative handling. We compared the new knotless anchor (BIOKNOTLESStrade mark RC; DePuy Mitek, Raynham, MA) with established absorbable and titanium suture anchors (UltraSorbtrade mark and Super Revo 5mmtrade mark; ConMed Linvatec, Utica, NY). Each anchor was tested on 6 human cadaveric shoulders. The anchors were inserted into the greater tuberosity. An incremental cyclic loading was performed. Ultimate failure loads, anchor displacement, and mode of failure were recorded. The anchor displacement of the BIOKNOTLESStrade mark RC (15.3 +/- 5.3 mm) after the first cycle with 75 N was significantly higher than with the two other anchors (Super Revo 2.1 +/- 1.6 mm, UltraSorb: 2.7 +/- 1.1 mm). There was no significant difference in the ultimate failure loads of the 3 anchors. Although the Bioknotlesstrade mark RC indicated comparable maximal pullout strength, it bares the risk of losing contact between the tendon-bone-interface due to a significantly higher system displacement. Therefore, gap formation between the bone and the soft tissue fixation jeopardizes the repair. Bioknotlesstrade mark RC should be used in the lateral row only when a double row technique for rotator cuff repair is performed, and is not appropriate for rotator cuff repair if used on its own.     

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.     

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.     

Osteolysis is observed around both bioabsorbable and nonabsorbable anchors on serial magnetic resonance images of patients undergoing arthroscopic rotator cuff repair

ObjectivesThe objective of this study was to evaluate the incidence of osteolysis around the bioabsorbable and nonabsorbable anchors using serial magnetic resonance imaging (MRI) and to determine the relationship between osteolysis and the retear rate after arthroscopic rotator cuff repair.MethodsFrom July 2012 to July 2014, 50 patients [28 men and 22 women; mean age, 56.4 (range: 45–56) years] underwent arthroscopic rotator cuff repair for a medium-to large-size tear with double-row suture-bridge technique. The bioabsorbable anchors used in the medial row comprised hydroxyapatite-polylactic acid enantiomer, and the nonabsorbable anchors in the lateral row were polyetheretherketone (PEEK)-type anchors. All patients underwent MRI evaluation at 3, 6, and 12 months postoperatively to determine osteolysis and identify any retear.ResultsThe incidences of osteolysis at 3, 6, and 12 months postoperatively were 1%, 4%, and 6% with nonabsorbable anchors and 13%, 29%, and 39% with bioabsorbable anchors, respectively. The incidences of osteolysis were significantly higher with the bioabsorbable anchors than with the nonabsorbable anchors (P < 0.005 for all three follow-ups). There was no significant difference between osteolysis and non-osteolysis groups regarding the retear rate or retear size (P = 0.189 and 0.069, respectively).ConclusionsOsteolysis was common around bioabsorbable anchors used for arthroscopic rotator cuff repair, and it also occurred around the PEEK-type nonabsorbable anchors. The incidence of osteolysis of nonabsorbable anchors was significantly lower than that of bioabsorbable anchors. Osteolysis did not significantly affect rotator cuff retear after arthroscopic repair with either bioabsorbable or nonabsorbable anchors.Level of evidenceLevel III, Therapeutic Study.     

Suture anchor failure strength—An in vivo study

Suture anchors are increasingly used to secure tendons or ligaments to bone. These devices are applicable for arthroscopic shoulder stabilization and rotator cuff repair. This study reports the in vivo characteristics of four anchors, including one absorbable anchor composed of poly-L-lactic acid. Failure strength and method of failure were recorded for these anchors as a function of time. Samples of four anchors [Mitek G2, Zimmer Statak, Acufex TAG wedge, and the absorbable Arthrex expanding suture plug (ESP)] were implanted into ram femurs and harvested at intervals. Each bone-anchor-suture system was stressed to failure. The failure force and failure method was recorded. Mitek G2 and Statak suture anchors failed consistently at 30 pounds by suture breakage. They had no implantation difficulties. The TAG wedge exhibited suture pull-out and implant flipping at insertion. The TAG wedge failed by suture cut-out, anchor pull-out, and suture breakage. Its average failure strength was initially 16 pounds, but increased to 28 pounds at 2 weeks and reached the 30-pound level by 4 weeks. The ESP poly-L-lactic acid anchors experienced implantation breakage in 20% because of their greater length and composition. At pull-out testing, the ESP failed by suture cut-out, anchor pull-out, and suture breakage. Failure strength was initially 27 pounds, was 17 pounds at 2 weeks, and increased to 30 pounds by 6 weeks. The absorbable ESP does not have initial pull-out strength comparable with the Mitek and Statak suture anchors but does achieve this strength by 6 weeks. This information should provide insight about the suitability of these suture anchors in the clinical setting.     

In vitro and finite element analysis of a novel rotator cuff fixation technique

The purpose of this investigation was to assess the biomechanic strength and stress dispersion at the repair site of surface-holding repair techniques for rotator cuff repair compared to the double-row technique. Eighteen bovine infraspinatus tendons were repaired using 3 different repair techniques: double-row repair, surface-holding repair with transosseous sutures, and surface-holding repair with knotless anchors. Biomechanical testing and two-dimensional finite element analysis were performed. The surface-holding repair with transosseous sutures provided 87.9% more stiffness than the double-row repair. The number of tendon-suture site failures of the surface-holding repair with transosseous sutures was smaller than the other 2 techniques. The finite element analysis showed that the surface-holding repair model had a more dispersing stress pattern compared to a double-row repair model. It suggests that these repair techniques can prevent high stress concentration compared to the double-row repair.     

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.     

LactoSorb plates for rotator cuff repair

Purpose: We present our preliminary studies using LactoSorb plates (Lorenz/Biomet, Warsaw, IN) for rotator cuff repair in humans. The use and application of this plate are described as an adjunct to prevent hole migration in trough-tunnel repairs of rotator cuff tears. Methods: Fifty patients with rotator cuff tears documented by magnetic resonance imaging underwent arthroscopic subacromial decompression followed by a mini-open repair of the rotator cuff. Tears were repaired using a trough and tunnel technique, horizontal mattress sutures, and a standard LactoSorb plate. Follow-up was obtained on 45 patients, 26 male and 19 female, with an average age of 61.6 years. The patients were followed-up and evaluated at 5 days, 1 month, 3 months, 6 months, and a minimum of 1 year postoperatively. All surgeries were performed by the same surgeon and followed a similar rehabilitation protocol. Results: There were 89% excellent results, 9% good results, and 2% fair results. There were no poor results. No significant swelling, tenderness, or erythema was noted at the operative site, and there were no infections. Postoperative radiographs at 3, 6, and 12 months did not show any bone erosion. No repeat surgical procedures were necessary. Conclusion: The results of our study support the use of LactoSorb bioabsorbable plates in the repair of rotator cuff tears to prevent hole migration and potentially poor results or failures of repairs. The LactoSorb plate appears to maintain its strength during the healing period of the repair and does not elicit any clinically noticeable inflammatory process.Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 18, No 3 (March), 2002: pp 279–283