Cyclic loading biomechanical analysis of the pullout strengths of rotator cuff and glenoid anchors: 2013 update

A Knotless Single-Row Suture Bridge Technique to Repair a Partial Articular Suproaspinatus Tendon Avulsion-Type Rotator Cuff Tear: Surgical Technique

With improving surgical and technological solutions for repairing rotator cuff tears, there has been increased interest in treatment of partial rotator cuff tears. The most prevalent type of partial tear is the PASTA (partial articular supraspinatus tendon avulsion) lesion. There is an ongoing debate on the best surgical technique to repair a PASTA lesion, which has led to the development of many different arthroscopic techniques. This Technical Note provides a cost-effective and reproducible technique of a transtendinous single-row bridge repair of PASTA lesions, using two 1.8 FiberTak Knotless Soft Anchors.

Retrospective Comparative Analysis of Clinical and Functional Outcome After Arthroscopic Bankart Repair using All-Suture Anchor and Metal Anchor

Introduction

Both knotted all suture anchors and metal anchors are used for arthroscopic Bankart repair. We retrospectively evaluated and compared clinical and functional outcomes after arthroscopic Bankart repair using the knotted all-suture anchors and knotted metal anchors.

Materials and methods

In a retrospective cohort analysis, patients who underwent arthroscopic Bankart repair without any concomitant additional lesion repair using either all-suture anchors or metal anchors, between January 2015 and May 2018 were identified. Their pre- and post-operative functional and clinical outcomes were compared using Rowe and WOSI scores. The recurrence rate in the two groups was also compared.

Results

A total of 41 patients in all suture anchors group and 47 in the metal anchors group were identified as per inclusion and exclusion criteria. The demographic profile of both groups was comparable. There was no significant difference in clinical and functional outcome between the two suture anchor groups as per Rowe (pre-operative 40.13+6.51 vs 38.09+6.24 and post-operative 2 years 93.28+7.09 vs 92.55+9.2) and WOSI (pre-operative 943.05+216.64 vs 977.55+165.46 and post-operative 2 years 278.21+227.56 vs 270.94+186.25) scores. There was a significant improvement in both the groups between preoperative and post-operative ROWE and WOSI scores at 6 months and 2 years follow-up as compared to pre-operative scores (p<0.001). Re-dislocation rates were also comparable (4.8% vs 6.3%).

Conclusion

All-suture anchors showed comparable clinical and functional results as the metal anchors for arthroscopic Bankart repair at two-year follow-up.

Refixation of the anterior cruciate ligament: A biomechanical analysis of suture techniques in a porcine model

Purpose

Refixation of acute anterior cruciate ligament (ACL) tears represents an increasingly popular treatment option. Systematic evaluations of various suture technique parameters are still pending. We therefore aimed to evaluate the mechanical pull-out outcomes of various suture methods for optimization of ACL refixation.

Methods

Sixty fresh knees from mature domestic pigs were dissected and the femoral attachment of the ACL was peeled off. The 60 knees were divided in 10 groups and sutured as follows: (A) one suture (1, 2, 4 and 6 passes), (B) two sutures (2, 4 and 6 passes each; sutures knotted together as a loop) and (C) two sutures (2, 4 and 6 passes each, sutures knotted separately). The pull-out test was conducted using a validated electrodynamic testing machine. First occurrence of failure, maximum pull-out load and stiffness were measured. Suture failure was defined as pull-out of the ACL.

Results

Two-point fixation, using two sutures, with at least two passes, showed the most favourable biomechanical stability. The maximum pull-out load was significantly higher with two sutures (529.5 N) used compared to one (310.4 N), p < 0.001. No significant differences were found for maximum pull-out loads between two-point fixation versus one-point fixation but stiffness was significantly higher with two-point fixation (107.4 N/mm vs. 79.4 N/mm, p < 0.001). More passes resulted in higher maximum pull-out loads.

Conclusion

The results suggest using two independent sutures, refixed separately and at least two suture passes, is appropriate for ACL refixation. More suture passes provide additional strength but are technically challenging to achieve during surgery.

Level of Evidence

Level IV.

An additively manufactured titanium tilting suture anchor: a biomechanical assessment on human and ovine bone specimens

Introduction

A novel titanium tilting suture anchor was designed and fabricated using additive manufacturing. The anchor enjoyed a nonsymmetrical structure to facilitate its insertion procedure through a weight-induced tilt, a saw-teeth penetrating edge to provide a strong initial fixation into cancellous bones of various densities, and an appropriate surface texture to enhance the longterm fixation strength through bone ingrowth.

Methods

Biomechanical tests were performed on 10 ovine and 10 human cadaveric humeri to examine the insertion procedure and assess the initial fixation strength of the anchor, in comparison with a standard screw-type anchor as control.

Results

This study indicated a simple yet reliable insertion procedure for the tilting anchor. All anchors survived after 400 cycles of cyclic loadings and failed in the load-to-failure step. There were no significant differences between the displacements and fixation stiffnesses of the anchors in either group. The ultimate failure load was significantly smaller (p<0.05) for tilting anchors in ovine group (273.7 ± 129.72 N vs. 375.6 ± 106.36 N), but not different in human group (311.8 ± 82.55 N vs. 281.9 ± 88.35). Also, a larger number of tilting anchors were pulled out in ovine group (6 vs. 3) but a smaller number in human group (4 vs. 6).

Conclusion

It was concluded that the biomechanical performance of the designed tilting anchor is comparable with that of the standard screw-type anchors.

Comparing the biomechanical properties of conventional suture and all-suture anchors using patient-specific and realistic osteoporotic and non-osteoporotic phantom using 3D printing

Conventional suture anchors (CAs) and all-suture anchors (ASAs) are used for rotator cuff repair. Pull-out strength (POS) is an important factor that affects surgical outcomes. While the fixation mechanism differs between the anchor types and relies on the quality, few studies have compared biomechanical properties of anchors based on bone quality. This study aimed to compare the biomechanical properties of anchors using osteoporotic bone (OB) and non-osteoporotic bone (NOB) simulators. Humerus simulators were fabricated using fused deposition modeling of 3D printing and acrylonitrile butadiene styrene adjusting the thickness of cortical bone and density of cancellous bone based on CT images. Cyclic loading from 10 to 50 N, 10 to 100 N, and 10 to 150 N for 10 cycles was clinically determined at each anchor because the supraspinatus generates a force of 67-125 N in daily activities of normal control. After cyclic loading, the anchor was extruded at a load of 5 mm/min. Displacement, POS, and stiffness were measured. In OB simulators, CAs revealed bigger gap displacement than ASAs with cyclic loading of 10-150 N. ASA showed higher values for POS and stiffness. In NOB simulators, ASAs revealed bigger gap displacement than CAs with cyclic loading of 10-150 N. ASA showed higher values for POS and CA showed higher values for stiffness. POS of anchors depends on anchors 'displacement and bone stiffness. In conclusion, ASA demonstrated better biomechanical performance than CA in terms of stability under cyclic loading and stiffness with similar POS in OB.

Fixation strength in arthroscopic labral repair of the hip: A head-to-head comparison of the biomechanical performance of a biocompatible vs. all-suture anchor in the setting of acetabuloplasty

Much is known about the biomechanical performance of various types of suture anchors commonly used for labral fixation in the shoulder; however, similar studies in the hip are less common. We sought to compare all-suture and polyether ether ketone small-diameter anchors in the setting of labral repair during hip arthroscopy, with and without acetabuloplasty. We hypothesized that the biomechanical properties of the all-suture group when compared to polyether ether ketone anchors would be similar amongst native acetabula and significantly less following acetabuloplasty and that pullout forces would be reduced in the anterior and inferior regions of the acetabulum compared to the superior region. Bone density was measured in nine matched pairs of fresh-frozen cadaveric acetabula in the superior, anterosuperior, and anterior regions. Acetabuloplasty was performed in all three regions, while the contralateral acetabulum was left in situ as a control. Suture anchors were placed such that one each of two different types was placed within each region. Specimens were tested in cyclic fatigue and loaded to failure. The all-suture group had significantly higher cyclic displacement compared to the polyether ether ketone, but there was no significant difference in ultimate load, regardless of acetabuloplasty. Amongst all non-resected specimens, the lowest bone density was observed consistently in the inferior region. Our results indicate that, with or without acetabuloplasty, a small-diameter polyether ether ketone anchor appears to be more stable than an all-suture anchor, which needs to be set first.

UHMWPE suture induced pseudotumor following arthroscopic rotator cuff repair: A case report

UHMWPE suture shows excellent biocompatibility and complication associated with suture debris had not been described before in shoulder surgery. In this study, a case of a 38-year-old man with a wear debris pseudotumor mimicking osteochondromatosis in the subacromial bursa five years after arthroscopic rotator cuff repair using a composite braid suture (a polydioxanone core with a sleeve of UHMWPE) was presented. Histological examination confirmed the presence of suture fragments surrounded with the osteochondral layer without inflammatory reactions. The present study implies the potential risk of free fragmented remnants from the UHMWPE suture. Because of the silent nature of the histological response, a high index of suspicion should be necessary to disclose the chanciness of its use.

Clinical and radiological outcome of all-suture anchors in shoulder and elbow surgery

Background

All-suture anchors (ASAs) are noted to cause various bone reactions when used in upper limb surgery but clinical implications are unknown.

Methods

88 shoulders and 151 elbows with a mean follow-up of 47.1 ± 17.7 months were invited for follow-up including clinical examination, questionnaires and radiographs. The anchor drill holes were radiographically assessed.

Results

At final follow up, mean DASH was 12.9 ± 13.8 and mean VAS 2.2 ± 2.4 in the shoulder population. In the elbow group mean MEPS was 91.8 ± 12.7 and mean VAS 1.5 ± 1.9. Implant-specific complications were seen in 10 elbow cases but none in the shoulder group. The mean diameter of the 1.4 mm all-suture anchor drill hole was enlarged to 2.5 ± 1.4 mm in the shoulder group and to 2.9 ± 1.0 mm in the elbow group. 50% of the 1.4 mm anchor drill holes showed abnormal morphology but these morphologic changes did not correlate with clinical outcome, complications or reoperation rate.

Discussion

Satisfying clinical outcomes are found in upper limb surgery using ASAs. Various bone changes are seen after implantation of an ASA, but these are not clinically relevant. Long-term consecutive follow-up data is required.

Comparison of all-suture anchors with metallic anchors in arthroscopic cuff repair: Structural and functional properties and clinical suitability

Purpose

This study examined and compared all-suture anchors with metallic anchors in the arthroscopic repair of small to medium supraspinatus tears; a multi-dimensional evaluation protocol assessed (i) clinical, (ii) ultrasonographical, and (iii) functional criteria at mid-term.

Materials and methods

A sample of 40 patients, prescreened from a larger group who had undergone arthroscopic rotator cuff repair, were resolved into two groups of 20, based on the type of anchor used in their surgery (all-suture or metallic) and were evaluated postoperatively (mean = 44.3 months, SEM = 22.4 months, minimum period = 10.3 months). Clinical assessments included (i) objective and subjective scores (Constant, DASH, SPADI, SST), (ii) ultrasonographical examination, as well as (iii) isometric and isokinetic strength testing. Raw data from the operated side was compared with those from the contralateral side within each group. Raw data for the PROMs and for the US evaluation were compared between groups. Strength data, as well as the Constant score values, were further analyzed based on (i) the difference between operated and intact sides, as well as (ii) the strength ratio between operated and intact sides; the transformed data were then compared between the two groups.

Results

We found no statistically significant differences in any of the parameters considered between shoulders operated using ASAs or MAs, nor between operated and non-operated sides in each group.

Conclusion

Our findings indicate that the reliability and performance characteristics of all-suture anchors and metallic anchors are practically indistinguishable for arthroscopic treatment of small to medium lesions of the supraspinatus tendon.

Biomechanical comparison of different suture anchors used in rotator cuff repair surgery-all-suture anchors are equivalent to other suture anchors: a systematic review and network meta-analysis

PURPOSE

Suture anchors are commonly used to repair rotator cuff tendons in arthroscopy surgery, and several anchor materials have been created to maximize pull-out strength and minimize iatrogenic damage. We hypothesized that all-suture anchors have biomechanical properties equivalent to those of conventional anchors. Our purpose is to compare the biomechanical properties of different anchors used for rotator cuff repair.

METHODS

The Embase, PubMed, Cochrane, and Scopus databases were searched for biomechanical studies on various suture anchors. The search keywords included rotator cuff tears and suture anchors, and two authors conducted study a selection, risk of bias assessment, and data extraction. The failure load, stiffness, and displacement were calculated using the mean differences with 95% confidence intervals (CIs). Failure modes were estimated using summary odds ratios with 95% CIs. The surface under the cumulative ranking curve was used for the relative ranking probabilities. A sensitivity analysis was performed by excluding studies using synthetic bones.

RESULTS

The polyetheretherketone (PEEK) (p < 0.001) and all-suture anchors (p < 0.001) had higher failure loads than the biocomposite anchors, whereas no significant difference was observed in stiffness among the anchors. The all-suture (p = 0.006) and biocomposite anchors (p < 0.001) had displacements higher than the metal anchors. The relative ranking of the included anchors in failure loads and displacement changed in sensitivity analysis. The meta-analysis did not find significant differences, but the relative ranking probabilities suggested that all-suture anchor had a higher rate of anchor pull-out and a lower rate of eyelet or suture breakage. In contrast, the metal anchors were associated with a higher number of eyelet breakage episodes.

CONCLUSIONS

All-suture anchors showed significantly higher failure loads than the biocomposite anchors and similar cyclic displacements to the biocomposite and PEEK anchors. There were no significant differences in stiffness between all-suture and conventional suture anchors. The relative ranking of biomechanical properties changed in sensitivity analysis, suggesting the potential effect of bone marrow density.

LEVEL OF EVIDENCE

Level IV.

Arthroscopic Superior Capsular Reconstruction (ASCR): All Soft Anchors Technique

Rotator cuff tears are among the most common orthopaedic injuries. If not treated, they can result in a massive irreparable tear because of tendon retraction and muscle atrophy. Mihata et al. in 2012 described the technique of superior capsular reconstruction (SCR) using fascia lata autograft. This has been considered an acceptable and effective method for treating irreparable massive rotator cuff tears. We describe an arthroscopically assisted superior capsular reconstruction (ASCR) technique using all soft anchors to preserve the bone stock and reduce possible hardware complications. Moreover, knotless anchors for the lateral fixation make the technique easier to reproduce.

Revision Arthroscopic Labral Repair Using All-Suture Anchors in Patients With Subcritical Glenoid Bone Loss After Failed Bankart Repair: Clinical Outcomes at 2-Year Follow-up

Background

All-suture anchors have been used for primary arthroscopic Bankart repair because of their ability to minimize initial bone loss.

Purpose

To evaluate the clinical efficacy of using all-suture anchors in revision arthroscopic labral repair after failed Bankart repair.

Study Design

Case series; Level of evidence, 4.

Methods

Enrolled in this study were 28 patients who underwent revision arthroscopic labral repair with all-suture anchors after a failed primary arthroscopic Bankart repair. Revision surgery was determined for patients who had a frank redislocation history with subcritical glenoid bone loss (<15%), nonengaged Hill-Sachs lesion, or off-track lesion. Minimum 2-year postoperative outcomes were evaluated using shoulder range of motion (ROM), the Rowe score, the American Shoulder and Elbow Surgeons (ASES) score, apprehension, and the redislocation rate. Postoperative shoulder anteroposterior radiographs were assessed to evaluate arthritic changes in the glenohumeral joint.

Results

The mean patient age was 28.1 ± 6.5 years, and the mean time between primary Bankart repair and revision surgery was 5.4 ± 4.1 years. Compared with the number of suture anchors used in the primary operation, significantly more all-suture anchors were inserted in the revision surgery (3.1 ± 0.5 vs 5.8 ± 1.3, P < .001). During the mean follow-up period of 31.8 ± 10.1 months, 3 patients (10.7%) required reoperation because of traumatic redislocation and symptomatic instability. Of patients with symptoms that did not require reoperation, 2 patients (7.1%) had subjective instability with apprehension depending on the arm position. There was no significant change between preoperative and postoperative ROM. However, ASES (preoperative: 61.2 ± 13.3 to postoperative: 81.4 ± 10.4, P < .01) and Rowe (preoperative: 48.7 ± 9.3 to postoperative: 81.7 ± 13.2, P < .01) scores were significantly improved after revision surgery. Eight patients (28.6%) showed arthritic changes in the glenohumeral joint on final plain anteroposterior radiographs.

Conclusion

Revision arthroscopic labral repair using all-suture anchors demonstrated satisfactory 2-year clinical outcomes in terms of functional improvement. Postoperative stability was obtained in 82% of patients without recurrent shoulder instability after failed arthroscopic Bankart repair.

Soft Anchors for Rotator Cuff Repair: A Review

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All-suture anchors or so-called "soft" anchors, initially adapted for labral repairs, have increased in popularity for use in rotator cuff repair because of their smaller size, decreased occupation of the footprint, improved points of fixation, ease of use, and ease of revision.

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In limited series, soft anchors have demonstrated equivalent biomechanical and clinical performance compared with hard body anchors for rotator cuff repair.

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Perianchor cyst formation can occur with both hard body and soft anchors.

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Biomechanical and clinical data support aiming for vertical angles of insertion for soft anchors.

An Injectable Calcium Phosphate Bone Graft Substitute Improves the Pullout Strength of Various Suture Anchor Designs in an Osteoporotic Bone Model

Purpose

To compare various suture anchor designs with and without calcium phosphate (CaP) augmentation in an osteoporotic foam block model and decorticated proximal humerus cadaveric model.

Methods

This was a controlled biomechanical study, consisting of 2 parts: (1) an osteoporotic foam block model (0.12 g/cc; n = 42) and (2) a matched pair cadaveric humeral model (n = 24). Suture anchors selected were an all-suture anchor, PEEK (polyether ether ketone)-threaded anchor, and a biocomposite-threaded anchor. For each study arm, one half the samples were first filled with injectable CaP and the other half were not augmented with CaP. For the cadaveric portion, the PEEK- and biocomposite-threaded anchors were assessed. Biomechanical testing consisted of a stepwise, increasing load protocol for a total of 40 cycles, followed by ramp to failure.

Results

For the foam block model, the average load to failure for anchors with CaP was significantly greater when compared with anchor fixation augmented without CaP; the all-suture anchor was 135.2 ± 20.2 N versus 83.3 ± 10.3 N (P = .0006); PEEK was 131 ± 34.3 N versus 58.5 ± 16.8 N (P = .001); and biocomposite was 182.2 ± 64.2 N versus 80.8 ± 17.4 N (P = .004). For the cadaveric model, the average load to failure for anchors augmented with CaP was again greater than anchor fixation without CaP; PEEK anchors went from 41.1 ± 21.1 N to 193.6 ± 63.9 N (P = .0034) and biocomposite anchors went from 70.9 ± 26.6 N to 143.2 ± 28.9 N (P = .004).

Conclusions

Augmenting various suture anchors with CaP has shown to significantly increase pull-out strength and stiffness in an osteoporotic foam block and time zero cadaveric bone model.

Clinical Relevance

Rotator cuff tears are common in the elderly patients, in whom poor bone quality jeopardizes treatment success. Exploring methods that increase the strength of fixation in osteoporotic bone to improve outcomes in this patient population is important.

Arthroscopic repair of rotator cuff injury with bioabsorbable suture anchor vs. all-suture anchor: a non-inferiority study

BACKGROUND

Compare all-suture anchors to traditional anchors through clinical and radiological evaluation at pre-established end-points.

MATERIALS AND METHODS

We performed a two-arms non-inferiority study on all-suture anchor (2.3 iconix™, Stryker) device with respect to traditional anchor (5.5 healix Advance™ BR, Depuy/Mitek) device under unpaired samples with size equal to 30 patients per group, all suffering from supraspinatus tendon rupture. We administrated DASH (Disabilities of the Arm, Shoulder and Hand); constant; and SST (Simple Shoulder Test) questionnaires in pre-operative, 3 ± 1 months post-intervention and 8 ± 1 months post-intervention. Questionnaires scores were the primary outcome. We also evaluated RMI at 3 and at 8 months after surgery to assess the presence of oedema or any loosening of the implant.

RESULTS

All-suture anchor approach has been proven to have non-inferior performances with respect to traditional anchor approach, according to questionnaires scores at the 3-month endpoint. We observed 26 patients with oedema by MRI (18 in control group, 6 in experimental group). In the 8-month endpoint we found persistent edema in 12 patients (all treated with healix), 2 had mobilitazions (healix), 10 had partial retears (8 healix, 2 iconix) and 1 implant failure (healix).

CONCLUSIONS

All suture devices have clinical and functional results comparable to traditional devices, while they tend to give fewer complications in terms of bone edema, loosening and retear rate. The effectiveness of all-suture devices should be further investigated in rotator cuff suture arthroscopic revision surgery, given the advantages they offer.

Manufacture of Soft-Hard Implants from Electrospun Filaments Embedded in 3D Printed Structures

Rotator cuff tendon tears are common injuries of the musculoskeletal system that often require surgical repair. However, re-tearing following repair is a significant clinical problem, with a failure rate of up to 40%, notably at the transition from bone to tendon. The development of biphasic materials consisting of soft and hard components, which can mimic this interface, is therefore promising. Here, a simple manufacturing approach is proposed that combines electrospun filaments and 3D printing to achieve scaffolds made of a soft polydioxanone cuff embedded in a porous polycaprolactone block. The insertion area of the cuff is based on the supraspinatus tendon footprint and the size of the cuff is scaled up from 9 to 270 electrospun filaments to reach a clinically relevant strength of 227N on average. The biological evaluation shows that the biphasic scaffold components are noncytotoxic, and that tendon and bone cells can be grown on the cuff and block, respectively. Overall, these results indicate that combining electrospinning and 3D printing is a feasible and promising approach to create soft-to-hard biphasic scaffolds that can improve the outcomes of rotator cuff repair.

Risk Factors and Corresponding Management for Suture Anchor Pullout during Arthroscopic Rotator Cuff Repair

INTRODUCTION

Due to the aging of the population, the incidence of rotator cuff tears is growing. For rotator cuff repair, arthroscopic suture-anchor repair has gradually replaced open transosseous repair, so suture anchors are now considered increasingly important in rotator cuff tear reconstruction. There are some but limited studies of suture anchor pullout after arthroscopic rotator cuff repair. However, there is no body of knowledge in this area, which makes it difficult for clinicians to predict the risk of anchor pullout comprehensively and manage it accordingly.

METHODS

The literature search included rotator cuff repair as well as anchor pullout strength. A review of the literature was performed including all articles published in PubMed until September 2021. Articles of all in vitro biomechanical and clinical trial levels in English were included. After assessing all abstracts (n = 275), the full text and the bibliographies of the relevant articles were analyzed for the questions posed (n = 80). Articles including outcomes without the area of interest were excluded (n = 22). The final literature research revealed 58 relevant articles. Narrative synthesis was undertaken to bring together the findings from studies included in this review.

RESULT

Based on the presented studies, the overall incidence of anchor pullout is not low, and the incidence of intraoperative anchor pullout is slightly higher than in the early postoperative period. The risk factors for anchor pullout are mainly related to bone quality, insertion depth, insertion angle, size of rotator cuff tear, preoperative corticosteroid injections, anchor design, the materials used to produce anchors, etc. In response to the above issues, we have introduced and evaluated management techniques. They include changing the implant site of anchors, cement augmentation for suture anchors, increasing the number of suture limbs, using all-suture anchors, using an arthroscopic transosseous knotless anchor, the Buddy anchor technique, Steinmann pin anchoring, and transosseous suture repair technology.

DISCUSSION

However, not many of the management techniques have been widely used in clinical practice. Most of them come from in vitro biomechanical studies, so in vivo randomized controlled trials with larger sample sizes are needed to see if they can help patients in the long run.

Biomechanical analysis of the interval slide procedure: a fresh porcine cadaver study

INTRODUCTION

The interval slide procedure (IS) has been introduced to improve mobility in massive, retracted rotator cuff tears. As clinical studies showed controversial results, the benefit of the IS is still widely discussed.

AIM

Aim of this study was to analyze the effect of IS procedure on tendon mobility in a fresh porcine cadaver model.

MATERIALS AND METHODS

In 30 fresh porcine cadaver shoulders with artificial supraspinatus defect tendon mobility was tested by measuring the load (in N) during tendon reduction to the footprint at the greater tubercle using a sensor enhanced arthroscopic grasper (t1). In intervention group (N = 15) anterior IS (t2), posterior IS (t3) and intraarticular capsule release (t4) were successively performed, each followed by tendon mobility assessment. Tendon mobility of the control group (N = 15) was measured in same time schedule without intervention.

RESULTS

Mobility did not differ between groups for native tendons (CG 28.0 ± 11.2 N vs. IG 26.6 ± 11.6 N; P = 0.75). IS procedure significantly improves mobility at about 25.2% (t1 26.6 ± 11.6 N vs. t4 19.9 ± 12.3 N; P < 0.001) compared to the native tendon and 34.1% compared to CG (CG 30.2 ± 13.7 N vs. 19.9 ± 12.3 N; P = 0.026). In posthoc analyzes, anterior IS (P < 0.001) and capsule release (P = 0.005) significantly increased mobility, whereas the posterior IS did not (P = 0.778).

CONCLUSION

The IS procedure results in increased supraspinatus tendon mobility in fresh porcine cadaver shoulders. However, performing the posterior IS subsequent to the anterior IS no significant improvement of mobility has been observed.

Comparison of biomechanical analysis of four different tibial tunnel fixations in a bovine model

BACKGROUND

To determine the ideal fixation technique for an ACL reconstruction with a hamstring graft, multiple studies have been undertaken to define the initial biomechanical properties of tibial fixation.

PURPOSE

The aim of this study was to compare the biomechanical properties of tibial fixation methods by creating single or hybrid systems.

METHODS

Bovine tibias and forefoot digital extensor tendons were prepared with four different tibial anterior cruciate ligament fixation methods and compared biomechanically. Fixation materials included polyethylene Ultrabraid high-strength sutures, Biosure interference screws (Smith and Nephew, Memphis, TN, USA), staples (Smith and Nephew, Richards Regular Fixation Staples without Spikes, Memphis, TN, USA), and knotless suture anchors (Multifix-S PEEK) (Smith and Nephew, Memphis, TN, USA). Four groups (n = 5 specimens) were established - group I: single fixation with interference screws; group II: single fixation with knotless anchors; group III: hybrid fixation with interference screws and staples; group IV: hybrid fixation with interference screws and knotless anchors. Each specimen underwent evaluations for cyclic displacement, cyclic stiffness, initial loading strength, ultimate failure load, pull-out displacement, and pull-out stiffness.

RESULTS

All specimens completed cyclic loading and load-to-failure. The cyclic displacement in group II, which had a single fixation, indicated significantly greater elongation compared with the other groups (P = 0.002). The hybrid systems were more rigid than the single systems in terms of cyclic stiffness, and no statistically significant difference was observed between the hybrid systems (P = 0.461). Group IV was significantly superior in terms of the ultimate failure load (P = 0.004). No statistically significant differences were noted between the groups for pull-out displacement or pull-out stiffness.

CONCLUSION

Single fixation with bioscrews as an in-tunnel tibia fixation method was as successful as hybrid systems. Multifix-S PEEK knotless suture anchors, which can be combined with bioscrews, can be a superior fixation alternative due to its flexibility and ultimate failure load values.

No Difference Between Anchorless and Traditional Suture Anchors in Arthroscopic Bankart Repair: A Clinical Comparison

Background

Shoulder instability and recurrent dislocations are common problems encountered by orthopedic surgeons and are frequently associated with a Bankart lesion. These are classically treated with either open or arthroscopic repair utilizing traditional suture anchors, though anchorless fixation techniques have recently been developed as an alternate fixation method that reduces native bone loss and has comparable pull-out strength.

Methods

A retrospective review was performed at a single institution for patients who underwent Bankart repair from January 2008 through February 2014. American Shoulder and Elbow Surgeons (ASES) questionnaires were mailed to 35 patients with anchorless fixation and 35 age-, gender-, and surgeon-matched patients with traditional suture anchors. Statistical analysis was performed comparing re-dislocation, additional surgery, and ASES scores with statistical significance set at p < 0.05.

Results

Eleven patients in the anchorless implant group and 15 patients in the anchor group completed the questionnaire. The mean follow-up was 4.1 years in the anchorless group and 5.6 years in the anchor group (p=0.04). The number of implants was 4.82 in the anchorless group and 3.87 in the anchor group (p = 0.04). No difference was found in re-dislocation rates (p = 0.80) or additional surgery on the affected shoulder (p = 0.75). ASES scores were found to have no statistical difference (89.89 for the anchorless group versus 85.37 for the anchor group; p = 0.78).

Conclusion

In patients undergoing arthroscopic Bankart lesion repair with traditional anchors compared to anchorless fixation, there appears to be no difference in shoulder re-dislocation rates, recurrent ipsilateral shoulder surgery, or ASES scores.

Allograft and autograft provide similar retear rates for the management of large and massive rotator cuff tears: a review and meta-analysis

PURPOSE

Currently, autografts and allografts are largely used to treat large or massive rotator cuff tear (RCT), without any evidence in favour of one graft or the other. The purpose of this study was to determine the rate of retear of autograft and allograft in the treatment of large or massive posterosuperior RCT.

METHOD

The PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines were followed to perform this systematic review and meta-analysis of the results in the literature as well as the presentation of results. A search of the literature was performed in the electronic databases MEDLINE, Scopus, Embase, and the Cochrane Library. The quality of the included studies was evaluated according to the MINORS (Methodological Index for Nonrandomized Studies) score. Inclusion criteria were studies in English evaluating clinical and radiological results of surgical treatment with autograft or allograft for large or massive RCT since 2008. The main criterion was the retear rate of the graft assessed on MRI or US scan at 1-year minimum follow-up. Partial tear were classified as "tear".

RESULTS

The overall retear rate was 23.6% (15.5-32.7) at a mean follow-up of 18.4 ± 7.8 (12-36) months. There was no significant difference between the two kinds of graft, with a retear rate of 27.0% (15.4-40.2) and 20.9% (9.9-34.2) with autograft and allograft respectively (n.s.). Similar improvements of functional scores (+ 28.8 to 38.4 points for the Constant score, + 33.6 to 38.4 points for the ASES, and - 4.0 to - 4.1 points for pain-VAS) were reported in the two groups after at 27.2 ± 11.1 (12-48) months. The rate of complications except retear was 1.8% (0.2, 3.7) with autograft and 0.5% (0.8, 1.8) with allograft (n.s.).

CONCLUSION

The use of autograft and allograft for the treatment of large or massive RCT leads to similar retear rate and clinical outcomes at short to medium terms.

LEVEL OF EVIDENCE

Level IV.

No Clinical or Radiographic Difference Seen in Arthroscopic Bankart Repair With Knotted Versus Knotless Suture Anchors: A Randomized Controlled Trial at Short-Term Follow-Up

PURPOSE

The objective of this study was to compare the clinical and radiographic results of patients undergoing arthroscopic repair of labral lesions using knotted and knotless anchors.

METHODS

Sixty-four patients with anterior labral lesions (bone defects of the glenoid up to 13.5% or up to 20% if the instability severity index score was less than 4) and without other shoulder pathologies were randomly assigned to 2 groups, with 32 patients in each group. Clinical outcomes were assessed 6, 12, and 24 months after surgery by the Rowe score, Western Ontario shoulder instability index (WOSI), single assessment numeric evaluation (SANE), visual analog scale for pain (VASp), range of motion, and rate of postoperative recurrence. Postoperative magnetic resonance imaging (MRI) was performed, and the anterior and inferior labrum glenoid height indexes and anterior and inferior labral slopes were measured. The primary endpoint was the Rowe score at 24 months postoperatively.

RESULTS

Fifty-one patients, 24 in the knotted group and 27 in the knotless group, completed 24 months of follow-up. At 24 months, the Rowe scores were 81.7 ± 19.9 points and 85.9 ± 14 points, respectively (P = .623); the WOSI scores were 509.2 ± 480.1 points and 555.9 ± 393.6 points, respectively (P = .533); the SANE scores were 90.7 ± 18.7 points and 89.2 ± 14.8 points, respectively (P = .427); and the VASp scores were 1.7 ± 2.5 points and 2.5 ± 2.7 points, respectively (P = .275). There was no significant difference in range of motion, postoperative recurrence, or MRI parameters between the groups. All subjects (100%) in both groups exceeded the minimal clinically important difference of 9.7 for the Rowe score (P > .999).

CONCLUSION

Repair of Bankart's lesion through the use of knotted and knotless suture anchors yielded similar clinical and radiographic results on analysis at 24 months after operation.

LEVEL OF EVIDENCE

Level I. Randomized controlled clinical trial.

Beyond the pedicle screw-a patent review

PURPOSE

This review provides an overview of the patent literature on posteriorly placed intrapedicular bone anchors. Conventional pedicle screws are the gold standard to create a fixation in the vertebra for spinal fusion surgery but may lack fixation strength, especially in osteoporotic bone. The ageing population demands new bone anchors that have an increased fixation strength, that can be placed safely, and, if necessary, can be removed without damaging the surrounding tissue.

METHODS

The patent search was conducted using a classification search in the Espacenet patent database. Only patents with a Cooperative Patent Classification of A61B17/70 or A61B17/7001 concerning spinal positioners and stabilizers were eligible for inclusion. The search query resulted in the identification of 731 patents. Based on preset inclusion criteria, a total of 56 unique patents on different anchoring methods were included, reviewed and categorized in this study.

RESULTS

Five unique fixation methods were identified; (1) anchors that use threading, (2) anchors that utilize a curved path through the vertebra, (3) anchors that (partly) expand, (4) anchors that use cement and (5) anchors that are designed to initiate bone ingrowth. Of the anchor designs included in this study, eight had a corresponding commercial product, six of which were evaluated in clinical trials.

CONCLUSION

This review provides insights into worldwide patented intrapedicular bone anchors that aim to increase the fixation strength compared to the conventional pedicle screw. The identified anchoring methods and their working principles can be used for clinical decision-making and as a source of inspiration when designing novel bone anchors.

Arthroscopic Repair of Posterior Root Tears of the Lateral Meniscus with All-Suture Anchor

Meniscus root tears are increasingly being recognized and treated because of improved awareness and diagnostics. These injuries commonly occur in combination with knee ligament injuries. Untreated posterior meniscus root teats have been demonstrated to increase contact pressure and decrease contact area, ultimately leading to unfavorable joint loading and development of early osteoarthritis. Posterior lateral meniscus root tears (PLMRTs) also have been reported to increase anterior tibial translation and pivot shift in anterior cruciate ligament-deficient knees. Therefore, it is crucial to repair meniscal root tears when possible to restore knee joint loading and kinematics. Several techniques for repair of the PLMRT have been described. In this Technical Note, we describe our preferred technique for repair of PLMRT using an all-suture anchor. This technique is reproducible, does not need a tunnel, mitigates bungee effect of transtibial technique, and the anchor can easily be inserted on the footprint without a need for a guide.

Biomechanical analysis of bioabsorbable suture anchors for rotator cuff repair using osteoporotic and normal bone models

BACKGROUND

This study aimed to compare the failure load of suture anchors used in rotator cuff repair between normal and osteoporotic bone models.

METHODS

A total of 16 anchors made from metal (TwinFix Ti 5.0 or 6.5 mm, Corkscrew FT 4.5, 5.5, or 6.5 mm), polyether ether ketone (HEALICOIL PK [HC-PK] 4.5 or 5.5 mm, SwiveLock PK 4.75 or 5.5 mm), or bioabsorbable material (HEALICOIL RG [HC-RG] 4.75 or 5.5 mm, Corkscrew Bio 4.75, 5.5, or 6.5 mm, SwiveLock BC 4.75 or 5.5 mm) were included. Moreover, 10- and 5-pounds per cubic foot (pcf) Sawbone® models were set as normal and osteoporotic cancellous bone models, respectively. Pullout testing was performed in parallel to the insertion axis at a displacement rate of 12.5 mm/s using a universal testing machine. To evaluate the change in failure load between the two Sawbone® models with different densities, the remaining failure load ratio (RFLR) was defined as the ratio of the failure load in 10 pcf to that in 5 pcf.

RESULTS

In the 10-pcf Sawbone®, TwinFix Ti 6.5 mm showed the highest mean failure load (304.0 ± 15.2 N). In the 5-pcf Sawbone® model, HC-PK 5.5 mm showed the highest failure load (146.3 ± 5.8 N). Among anchors with the same diameter, HC-PK and HC-RG showed a significantly higher failure load than other anchors in the 10- and 5-pcf Sawbone® models. HC-PK 5.5 mm (62.1%) and HC-PK 4.5 mm (51.1%) have the highest RFLR among anchors with the same diameter.

CONCLUSIONS

HC-PK and HC-RG showed higher failure load than the other anchors in both normal and osteoporotic bone models, except for TwinFix Ti 6.5 mm in the 10-pcf Sawbone® model. Based on our results, bioabsorbable anchors had sufficient failure load for rotator cuff repair in addition to bioabsorbability.

The Evolution of Arthroscopic Rotator Cuff Repair

Over the past 30 years, arthroscopic rotator cuff repair (ARCR) has evolved to become the gold standard in treating rotator cuff pathology. As procedural concepts of ARCR continue to improve, it is also continually compared with the open rotator cuff repair as the historical standard of care. This review highlights the evolution of ARCR, including a historical perspective; the anatomic, clinical, and surgical implications of the development of an arthroscopic approach; how arthroscopy improved some of the problems of the open approach; adaptations in techniques and technologies associated with ARCR; future perspectives in orthobiologics as they pertain to ARCR; and lastly, the clinical improvements, or lack of improvements, with all of these adaptations.

Periimplant osteolysis does not affect the outcome of rotator cuff repair: a systematic review and meta-analysis

PURPOSE

The goal of this study was to perform a systematic review and meta-analysis to compare the clinical and radiologic outcomes of rotator cuff repair, depending on the presence of developed periimplant osteolysis (PIO) after using suture anchors.

METHODS

The electronic databases of MEDLINE, EMBASE, and the Cochrane Central Register of Controlled Trials were searched for articles published up until October 2019 to find relevant articles comparing the outcomes of rotator cuff repair between the periimplant osteolysis group and non-periimplant osteolysis group. Data searching, extraction, analysis, and quality assessment were performed according to the Cochrane Collaboration guidelines. The results are presented as risk ratio (RR) for binary outcomes and standardised mean difference (SMD) for continuous outcomes with 95% confidence intervals (CI).

RESULTS

Six clinical studies were included. No significant differences were found between the group with periimplant osteolysis and the group without periimplant osteolysis regarding retear rate (RR = 1.34; 95% CI 0.93-1.94; I² = 28%), postoperative clinical scores (SMD = 0.29; 95% CI - 0.26 to 0.83; I² = 80%) and range of motion (ROM); forward flexion (SMD = 0.39; 95% CI - 0.16 to 0.93; I² = 0%), external rotation (SMD = - 0.10; 95% CI - 0.64 to 0.45; I² = 0%) and internal rotation (SMD = - 0.37; 95% CI - 0.92 to 0.17; I² = 0%).

CONCLUSION

The presence of periimplant osteolysis after rotator cuff repair with suture anchor does not affect the clinical outcomes such as retear rate, clinical scoring, and ROM. However, as there was no standard consensus on the criteria for evaluating periimplant osteolysis, this result may not fully reflect the effect of periimplant osteolysis depending on its severity.

LEVEL OF EVIDENCE

Level IV.

Biomechanical analysis of arthroscopically assisted latissimus dorsi transfer fixation for irreparable posterosuperior rotator cuff tears-Knotless versus knotted anchors

We compared the construct stability of traditional knotted techniques with modern knotless anchor systems used in arthroscopically assisted latissimus dorsi transfers (aLDTs) for irreparable posterosuperior rotator cuff tears. Eighteen cadaveric shoulders were age- and gender-matched to the following three groups: knotted group (two knotted anchors); knotless group (two knotless anchors); and triple anchor group (two knotless anchors; one all-suture anchor at the apex of the humeral head). All tendons were cyclically loaded in line of the aLDT over 400 cycles followed by a load to failure test. Outcome measures were the ultimate load to failure, elongation, construct stiffness, and failure modes. The triple anchor group revealed the highest ultimate load to failure (431 ± 78 N) compared with the knotted (326 ± 52 N; p = .022) and knotless (353 ± 105 N; p = .129) groups. Total elongation and construct stiffness were not significantly different comparing all three groups. The failure modes were: anchor pull-out in all specimen of the knotted group; three (50%) anchor pull-out and three suture pull-out in the knotless group (p = .046); four (67%) anchor pull-out, one (17%) suture pull-out and one tendon pull-out in the triple anchor group. Biomechanical analyses of knotless fixation techniques for aLDTs show similar construct stability and elongation compared with the traditional, knotted techniques. Bone fixation seems to be improved with the knotless anchor systems. In our practice, we continue to use the knotless fixation technique for aLDT and in the situation of weak, osteoporotic bone, we add a third (all-suture) anchor to improve construct stability.

Biocompatibility and Biological Performance Evaluation of Additive-Manufactured Bioabsorbable Iron-Based Porous Suture Anchor in a Rabbit Model

This study evaluated the biocompatibility and biological performance of novel additive-manufactured bioabsorbable iron-based porous suture anchors (iron_SAs). Two types of bioabsorbable iron_SAs, with double- and triple-helical structures (iron_SA_2_helix and iron_SA_3_helix, respectively), were compared with the synthetic polymer-based bioabsorbable suture anchor (polymer_SAs). An in vitro mechanical test, MTT assay, and scanning electron microscope (SEM) analysis were performed. An in vivo animal study was also performed. The three types of suture anchors were randomly implanted in the outer cortex of the lateral femoral condyle. The ultimate in vitro pullout strength of the iron_SA_3_helix group was significantly higher than the iron_SA_2_helix and polymer_SA groups. The MTT assay findings demonstrated no significant cytotoxicity, and the SEM analysis showed cells attachment on implant surface. The ultimate failure load of the iron_SA_3_helix group was significantly higher than that of the polymer_SA group. The micro-CT analysis indicated the iron_SA_3_helix group showed a higher bone volume fraction (BV/TV) after surgery. Moreover, both iron SAs underwent degradation with time. Iron_SAs with triple-helical threads and a porous structure demonstrated better mechanical strength and high biocompatibility after short-term implantation. The combined advantages of the mechanical superiority of the iron metal and the possibility of absorption after implantation make the iron_SA a suitable candidate for further development.

Design and Mechanical Evaluation of Sutureless Implants for the Surgery Treatment of Rotator Cuff Tears

Rotator cuff (RC) tears cause pain and functional disability of the shoulder. Despite advances in suture anchors, there are still reports about the incidence of surgical-related injuries to RC mainly associated with sutures. The purpose of this study was to design and evaluate the mechanical behavior of sutureless implants to repair RC tears. We hypothesized that the implants present mechanical characteristics suitable for the surgical treatment of RC tears as suture anchors. Three different implants (T1, T2, T3) were designed and fabricated with titanium: T1 has two rods and rectangular head; T2 has two rods with a small opening and enlarged rectangular head; and T3 has three rods and a circular head. The implants were fixed in rigid polyurethane foam blocks by a series of blows, and the applied mechanical loads along with the number of blows were quantified. Pullout tests using tapes fixed between the implant head and testing machine grip were conducted until implant failure. The maximum pullout strength and displacement of the implant relative to the rigid foam block were computed. Statistical significance was set at p < 0.05. Owing to its geometric configuration, implant T2 presented the best characteristics related to stability, strength, and ease of insertion. Implant T2 confirms our hypothesis that its mechanical behavior is compatible with that of suture anchors, which could lead to the reduction of RC repair failures and simplify the arthroscopic procedure.

Fixationssysteme und Techniken zur arthroskopischen Rotatorenmanschettenrekonstruktion

Arthroskopische Rotatorenmanschettenrekonstruktionen wurden initial mit einer einreihigen („single row“) Technik beschrieben. Im Rahmen technischer Weiterentwicklungen der arthroskopischen Chirurgie wurden diverse Techniken zur zweireihigen („double row“), transossären und transossär-äquivalenten Sehnenfixation entwickelt, nicht zuletzt durch eine zunehmende Verbreitung knotenloser Anker. Die klinischen Ergebnisse zeigen keine relevanten Unterschiede zwischen den jeweiligen Techniken. Biomechanisch sind zweireihige Rekonstruktionen jedoch durch Vergrößerung der Kontaktfläche an der Insertionsstelle und der erreichten Stabilität überlegen, insbesondere mit medial geknoteten Fäden, welche in eine laterale Reihe als sog. Suture-Bridge abgespannt werden. Klassischerweise wurden Schraubanker aus Metall für eine arthroskopische Sehnenfixierung verwendet. Im Laufe der letzten Jahre wurde das Anker-Portfolio jedoch durch moderne bioresorbierbare und nichtresorbierbare (PEEK) Schraub- und Einschlaganker sowie auch um reine Fadenanker (All-suture) erweitert. Ein allgemeingültiger Goldstandard für die Ankerverwendung existiert bis dato nicht, wobei die meisten gängigen Anker – zumindest bei guter Knochenqualität – ausreichende Stabilität gewährleisten. Beim Nahtmaterial kam es ebenso zu relevanten Weiterentwicklungen, sodass dem Versagen der Nähte heutzutage weniger Bedeutung zukommt. Das Aufkommen von bandartigem Nahtmaterial (Tapes) konnte in diversen biomechanischen Studien seine Überlegenheit nachweisen, jedoch ist bei geknoteten Techniken mit Tapes aufgrund des womöglich negativen Einflusses durch größere Knoten Vorsicht geboten. Nicht zuletzt ist die mediale Stichposition möglichst nahe des Rotatorenkabels von großer Bedeutung, da der häufigste Versagensmechanismus einer Rotatorenmanschettenrekonstruktion mit modernem Naht- und Ankermaterial weiterhin ein Hindurchschneiden der Fäden durch das vorgeschädigte Sehnengewebe ist.

Comparative analysis of a locking plate with an all-suture anchor versus hook plate fixation of Neer IIb distal clavicle fractures

BACKGROUND

The coracoclavicular fixation with suture anchors adds stability to type IIb distal clavicle fractures fixed with a plate and screws when loaded to failure. The purpose of this study was to compare the clinical and radiological outcomes between the use of a locking compression plate (LCP) with all-suture anchor fixation and hook LCP fixation of Neer IIb distal clavicle fractures.

METHODS

A total of 82 consecutive patients who underwent plate fixation for Neer IIb distal clavicle fractures were included. The subjects were divided into two groups: an LCP with all-suture anchor fixation group and hook LCP fixation group. For clinical assessments, the American Shoulder and Elbow Surgeons score, Korean shoulder score (KSS), and Constant score were recorded. A percentage of the coracoclavicular distance (CCD%) was used to evaluate fracture reduction. Typical reported complications, such as secondary dislocation, implant failure or loosening, peri-implant fracture, acromion osteolysis, stiffness, peri-anchor osteolysis, postoperative acromioclavicular joint arthrosis, nonunion, or delayed union, were also analyzed.

RESULTS

There were no differences in the clinical and radiological outcomes at the final follow-up between the two groups. The period for bone union and CCD% showed no significant differences between groups. Stiffness at 3 months after surgery of LCP with all-suture anchor fixation (n = 3, 10.7%) was less than that of hook LCP fixation (n = 17, 31.5%). The complication rate also showed no significant differences between groups. However, LCP with all-suture anchor fixation had anchor-related complications, although it can reduce hook-related complications.

CONCLUSION

LCP with all-suture anchor fixation showed satisfactory outcomes in comparison with hook LCP fixation. In Neer IIb distal clavicle fractures, LCP with all-suture anchor fixation is a useful method for the maintenance of reduction, avoiding implant removal, and hook-related complications. However, anchor fixation should be carefully used, especially in osteoporotic patients or patients with underlying diseases.

LEVEL OF EVIDENCE

Level III, retrospective study.

Comparison between all-suture and biocomposite anchors in the arthroscopic treatment of traumatic anterior shoulder instability: A retrospective cohort study

Purpose

Suture anchors have revolutionized arthroscopic surgery, enabling direct soft tissue-to-bone repair. There are many types of anchors still used in arthroscopic shoulder operations. We sought to compare the clinical outcome of all-suture and biocomposite anchors when used in arthroscopic Bankart repair for patients suffering from anterior shoulder instability.

Methods

A single-center retrospective cohort study of 30 patients (mean age: 26.6 years, SD: 8.8 years, male/female ratio: 5/1, mean follow up: 28 months, SD: 23.8, range: 12-92) with anterior shoulder instability was conducted. Patients were divided into 2 groups based upon the type of suture anchors used for the Bankart repair: group A (14 patients) used only all-suture anchors and group B (16 patients) used only biocomposite anchors. Outcomes reported were postoperative dislocations, positive shoulder apprehension test, self-reported sense of shoulder instability, return to activities of daily living, return to sports, patient satisfaction and complications. Patient reported outcome measures (PROMs) used were the Rowe Score for Instability, Constant Shoulder Score, Walch Duplay Score, The American Shoulder and Elbow Surgeons (ASES) Shoulder Score, Oxford Shoulder Instability Score and external rotation at 90° of arm abduction, external rotation at 0° of arm abduction, forward flexion, abduction, adduction and internal rotation.

Results

Rates of postoperative shoulder dislocation demonstrated no significant difference between the 2 groups (p > .05). Four postoperative dislocations happened, two in each group (14.3% and 12.5% for all suture only and biocomposite only groups, respectively), with three of them being traumatic. In addition, no significant differences were observed amongst groups regarding shoulder apprehension test (group A: 85.7% vs. group B: 93.8%), sense of shoulder instability (7.1% vs. 6.3%), return to activities of daily living (group A: 85.7% vs. group B: 93.8%), return to sports (group A: 85.7% vs. group B: 87.5%), patient satisfaction (moderate level: group A 21.4% vs. group B 12.5%), and PROMs.

Conclusion

The short-term failure rate and clinical/functional outcomes of arthroscopic Bankart repair using all-suture anchors is similar to the use of biocompatible anchors.

Level of evidence

Level III, retrospective cohort study.

Arthroscopic Bankart revision using all suture anchor in recurrent anterior shoulder dislocation: A case report

•

All suture anchor has the same biomechanical strength as conventional metallic anchor.

•

Recurrent shoulder dislocation after arthroscopic Bankart repair is still a problem.

•

The all suture anchor technique offers benefit of bone preservation and strong fixation.

Introduction

Arthroscopic Bankart revision after recurrent shoulder dislocation is still a matter of discussion. Several factors are contributing to this injury. Recently the development of all suture anchors has grown in popularity in arthroscopic stabilization. It was proven to preserve bone stock, smaller in size thus more anchors can be made.

Presentation of case

We presented a case of 27-year-old woman with recurrent anterior dislocation after seven years of arthroscopic Bankart repair. Seven years before, we performed Bankart repair using three 2.8 mm fiber-wire anchor (FASTak® (Arthrex, Karsfield Germany)). For the revision surgery we performed arthroscopic revision using four all suture anchor technique (Y-Knot® Flex All-Suture Anchor, 1.3 mm – One strand of #2 Hi-Fi® (Conmed, New York)).

Discussion

From preoperative and intraoperative assessment, we found no anchor failure and no massive bony lesion. To preserve the bone stock we insert four all suture anchors between the old anchor. One year post-operative follow up showed that patient could gain normal range of movement. No early or late complications were observed.

Conclusion

Compared to the conventional metallic anchor, all suture anchor has the same biomechanical strength. Moreover due to its relatively small size, it can reserve bone stock and more anchors can be made thus adding more stability to the shoulder.

All-suture anchor pullout results in decreased bone damage and depends on cortical thickness

PURPOSE

To evaluate the influence of cortical and cancellous bone structure on the biomechanical properties of all-suture and conventional anchors and compare the morphological bone damage after their failure. The hypothesis of the study is that all-suture anchor pullout is less invasive and that the pullout force is influenced by the cortical thickness.

METHODS

Thirty human humeri were biomechanically tested as follows: starting with a load cycle from 20 to 50 N, a stepwise increase of the upper peak force by 0.05 N for each cycle at a rate of 1 Hz was performed. Analysis included maximum pullout strength for three different anchor implantation angles (45°, 90°, 110°) of the two anchor types. After anchor pullout, every sample underwent micro-CT analysis. Bone mineral density (BMD) and cortical thickness were determined at the anchor implantation site. Furthermore, the diameter of the cortical defect and the volume of the bone cavity were identified.

RESULTS

The maximum pullout strength of all-suture anchors demonstrates a strong correlation to the adjacent cortical thickness (r = 0.82, p ≤ 0.05) with at least 0.4 mm needed to withstand 200 N. No correlation could be seen in conventional anchors. Moreover, no correlation could be detected for local BMD in both anchors. All-suture anchors show a significantly narrower cortical defect as well as a smaller bone cavity following pullout (4.3 ± 1.3 mm vs. 5.3 ± 0.9 mm, p = 0.037; 141 mm³ vs. 212 mm³; p = 0.009). The cortical defect is largest if the anchors are placed at a 45° angle.

CONCLUSION

In contrast to conventional anchors, the pullout force of all-suture anchors depends on the thickness of the humeral cortex. Furthermore, all-suture anchors show a significantly smaller cortical defect as well as decreased bone damage in the case of pullout. Therefore, the clinical implication of this study is that all-suture anchors are advantageous due to their bone preserving ability. Also, intraoperative decortication should not be performed and cortical thickness should be preoperatively evaluated to decrease the risk of anchor failure.

Novel and reproducible technique coping with intraoperative anchor pullout during arthroscopic rotator cuff repair

PURPOSE

To evaluate the incidence of intraoperative anchor pullout during arthroscopic rotator cuff repair, to compare the outcomes of different methods of managing anchor pullout, and to introduce a new technique for anchor pullout.

METHODS

1076 patients who underwent arthroscopic rotator cuff repair using a single-row repair technique were included. In 483 patients, rotator cuff repair was performed using a screw-in type anchor, and in 593 patients, soft anchors were used. When intraoperative anchor pullout occurred, it was managed by buddy screwing, anchor insertion in a different location, cement augmentation, or by bar anchoring using a threaded Steinmann pin. Plain radiography and sonography were used to check anchor locations and healing.

RESULTS

Fifty-two patients experienced anchor pullout intra- or postoperatively (48 and four patients, respectively). Anchor pullouts were more frequently observed for larger tears, women, older patients, and in patients with preoperative stiffness (limitations of both active and passive movements of the affected shoulder joint). For screw-in type anchors, pullout during surgery occurred in 16 patients (3.3%, 16/483), and all were managed using the buddy screwing technique. For soft anchor cases, pullout occurred in 32 patients (5.4%, 32/593) and was managed by anchor insertion in a different location (17 patients), cement augmentation (two patients), or bar anchoring using a threaded Steinmann pin (13 patients). Three patients managed by buddy screwing and two patients managed by anchor insertion in a different location had anchor failure after repair. Tendon healing at 6 months was observed in 12/16 patients treated by buddy screwing, 11/17 treated by anchor insertion in a different location, 2/2 treated by cement augmentation, and 12/13 treated by bar anchoring with a threaded Steinmann pin.

CONCLUSION

Intraoperative anchor pullout during arthroscopic rotator cuff repair is an uncommon but cumbersome complication. There are some techniques already introduced to deal with this complication. In comparison, not one technique is overwhelmingly superior to others; however, our new technique which is bar anchoring with a threaded Steinmann pin could be another solution, since it could utilize primary anchor sites and results appear to be acceptable. Level of evidence III.

Initial Experience With a Bioresorbable Polymer Anchor

Background

Anchors are frequently used in reconstructive orthopedic surgery to achieve fixation of soft tissue to bone. Anchors vary with respect to material composition, configuration, and methods of fixation at the site of attachment. The fixation component of anchoring devices has generally evolved from metal-fabricated implants to various types of bioresorbable anchors. The SonicAnchor^TM (Stryker, Kalamazoo, MI USA) polymer implant provides a unique form of anchor fixation using SonicFusion^TM technology to achieve interdigitation within cancellous bone while being radiolucent and providing a small footprint.

Methods

During a four-year period, 116 patients underwent a reconstructive orthopedic foot and ankle surgical procedure with the use of at least one bioresorbable polymer anchor (SonicAnchor implant). There were 59 males and 57 females, with an average age of 42 years (range: 12-83 years).

Results

A total of 233 bioresorbable anchor (SonicAnchor) implants were used in 116 patients. Of the 116 patients, 108 (93.1%) achieved successful clinical healing of their surgery at their most recent follow-up. The average follow-up duration was 309 days (range: 14-1,429 days). Eight (6.9%) patients were lost to follow-up prior to clinical healing. Two (1.7%) patients underwent reoperation. Also, 65 (56%) patients had at least six months of follow-up and 36 (31%) had at least one year of follow-up.

Conclusions

This preliminary clinical trial of patients undergoing soft tissue repair or reconstruction with a bioresorbable polymer appears to perform comparably to other commercially available devices. The lack of adverse events, mechanical failures, or infections further supports the safety of this device.

Peri-anchor cyst formation after arthroscopic bankart repair: comparison between biocomposite suture anchor and all-suture anchor

Background

The purpose of this study is to investigate clinical outcomes and radiological findings of cyst formation in the glenoid around suture anchors after arthroscopic Bankart repair with either biocomposite suture anchor or all-suture anchor in traumatic anterior shoulder instability. We hypothesized that there would be no significant difference in clinical and radiological outcomes between the two suture materials.

Methods

This retrospective study reviewed 162 patients (69 in group A, biocomposite anchor; 93 in group B, all-suture anchor) who underwent arthroscopic Bankart repair of traumatic recurrent anterior shoulder instability with less than 20% glenoid defect on preoperative en-face view three-dimensional computed tomography. Patient assignment was not randomized.

Results

At final follow-up, the mean subjective shoulder value, Rowe score, and University of California, Los Angeles shoulder score improved significantly in both groups. However, there were no significant differences in functional shoulder scores and recurrence rate (6%, 4/69 in group A; 5%, 5/93 in group B) between the two groups. On follow-up magnetic resonance arthrography/computed tomography arthrography, the incidence of peri-anchor cyst formation was 5.7% (4/69) in group A and 3.2% (3/93) in group B, which was not a significant difference.

Conclusions

Considering the low incidence of peri-anchor cyst formation in the glenoid after Bankart repair with one of two anchor systems and the lack of association with recurrence instability, biocomposite and all-suture anchors in Bankart repair yield satisfactory outcomes with no significant difference.

Cyclic and Load-to-Failure Properties of All-Suture Anchors in Human Cadaveric Shoulder Greater Tuberosities

PURPOSE

The purpose of this study was to evaluate the cyclic displacement, stiffness, and ultimate load to failure of 3 all-suture anchors in human cadaveric greater tuberosities.

METHODS

Three all-suture anchors indicated for rotator cuff repair were tested in 14 matched pairs of human cadaver fresh-frozen humeri. Anchors were inserted at 3 locations from anterior to posterior along the greater tuberosity and placed 5 mm from the articular margin. The constructs were cycled from 10 to 60 N at 1 Hz for 200 cycles. The anchors that survived cycling were then subjected to a single pull to failure test. A Kruskal-Wallis 1-way analysis of variance on ranks was performed to compare the displacement, stiffness, and ultimate load to failure of the different anchors tested.

RESULTS

One matched pair was excluded because of poor bone quality; therefore, 13 matched pairs were included in the study. After 20, 100, and 200 cycles, there was no difference in median displacement between the anchors tested (P = .23, P = .21, P = .18, respectively). The median ultimate load-to-failure between the Iconix (295.2 N, 95% confidence interval [CI], 125-762.2), JuggerKnot (287.6 N, 95% CI, 152.9-584.4), and Q-fix (333.3 N, 95% CI, 165.0-671.9) showed no statistically significant difference (P = .58). After 20, 100, and 200 cycles, there was no difference in median stiffness between the anchors tested (P = .41, P = .19, P = .26 respectively). Displacement greater than 5 mm occurred in 0 Iconix anchors (0%), 1 JuggerKnot anchor (3.64%), and 2 Q-fix anchors (7.69%). One JuggerKnot anchor failed by anchor pullout during cyclic loading.

CONCLUSIONS

When tested in human cadaveric humeral greater tuberosities 3 all-suture anchors, the 2.9-mm JuggerKnot, the 2.8-mm Q-fix, and the 2.3-mm Iconix, showed no significant differences in median displacement or stiffness after 20, 100, or 200 cycles or in median ultimate load to failure. Although not statistically significant, the Iconix was the only anchor tested to have no failures, whereas the JuggerKnot had both a clinical and catastrophic failure and the Q-fix had 2 clinical failures.

LEVEL OF EVIDENCE

Level V, Controlled Laboratory Study.

Biomechanical Comparison of Knotless All-Suture Anchors and Knotted All-Suture Anchors in Type II SLAP Lesions: A Cadaveric Study

PURPOSE

To compare the biomechanical performance of knotless versus knotted all-suture anchors for the repair of type II SLAP lesions with a simulated peel-back mechanism.

METHODS

Twenty paired cadaveric shoulders were used. A standardized type II SLAP repair was performed using knotless (group A) or knotted (group B) all-suture anchors. The long head of the biceps (LHB) tendon was loaded in a posterior direction to simulate the peel-back mechanism. Cyclic loading was performed followed by load-to-failure testing. Stiffness, load at 1 and 2 mm of displacement, load to repair failure, load to ultimate failure, and failure modes were assessed.

RESULTS

The mean load to repair failure was similar in groups A (179.99 ± 58.42 N) and B (167.83 ± 44.27 N, P = .530). The mean load to ultimate failure was 230 ± 95.93 N in group A and 229.48 ± 78.45 N in group B and did not differ significantly (P = .958). Stiffness (P = .980), as well as load at 1 mm (P = .721) and 2 mm (P = .849) of displacement, did not differ significantly between groups. In 16 of the 20 specimens (7 in group A and 9 in group B), ultimate failure occurred at the proximal LHB tendon. Failed occurred through slippage of the labrum in 1 specimen in each group and through anchor pullout in 2 specimens in group A.

CONCLUSIONS

Knotless and knotted all-suture anchors displayed high initial fixation strength with no significant differences between groups in type II SLAP lesions. Ultimate failure occurred predominantly as tears of the proximal LHB tendon.

CLINICAL RELEVANCE

All-suture anchors have a smaller diameter than solid anchors, can be inserted through curved guides, preserve bone stock, and facilitate postoperative imaging. There is a paucity of literature investigating the biomechanical capacities of knotless versus knotted all-suture anchors in type II SLAP repair.

Clinical and functional outcomes of a novel transosseous device to treat rotator cuff tears: A minimum 2-year follow-up

PURPOSE

Despite the improvements in the repair equipment techniques of rotator cuff, a gold standard method has not been defined yet and transosseous fixation through deltoid-splitting (mini-open) approach is still regarded as a good option. The primary purpose of this study is to present satisfactory clinical and functional outcomes with a novel transosseous device in full-thickness rotator cuff tear through deltoid-splitting.

MATERIALS AND METHODS

This retrospective study was performed on 70 consecutive patients who underwent surgery by a single surgeon from June 2014 to June 2016 for a full-thickness rotator cuff tear and was managed with a novel transosseous device. Total number of patients, mean age, percentage of male and female patients, mean duration of follow-up, percentage of involvement of the dominant extremity, affected shoulder, and tear size were recorded. Functional and clinical outcomes were assessed baseline and postoperatively at 3 and 6 months and final follow-up using Disabilities of the Arm, Shoulder and Hand (Q-DASH) and Constant-Murley scores.

RESULTS

A total of 70 (49 (70%) female, 21 (30%) male) patients whose mean age was 58.66 ± 9.19 (38-77) years were included. The mean surgery time was 35.33 ± 5.34 (28-55) min. The mean follow-up time was 28.31 ± 3.03 (24-36) months. According to the DeOrio and Cofield classification, 15 (21.43%) tears were small, 33 (47.14%) medium, 16 (22.86%) large, and 6 (8.57%) massive. By the final follow-up, the mean Constant-Murley score had significantly improved from 27.67 ± 7.46 (13-41) to 81.25 ± 3.77 (74-87; p = 0.0001) and the Q-DASH score had decreased from 82.34 ± 10.37 (65.91-100) to 10.28 ± 6.88 (0-23.45; p = 0.0001). There were no significant differences in the Constant-Murley or Q-DASH score at baseline-final follow-up between the small, medium, large, and massive tear groups (p > 0.05).

CONCLUSIONS

Treatment of full-thickness rotator cuff tear using this novel transosseous device significantly improved functional and clinical scores. However, further long-term prospective randomized multicenter trials involving comparative studies are necessary to confirm these findings.

Pullout strength and failure mode of industrially manufactured and self-made all-suture anchors: a biomechanical analysis

BACKGROUND

This study presents a new technique for assembling an all-suture anchor from existing medical products. The biomechanical characteristics of this self-made anchor (SMA) are compared with those of an industrially manufactured all-suture anchor.

METHODS

The SMAs were made from established medical products (FiberWire #2 and 2-mm FiberTape; Arthrex, Naples, FL, USA). Pretesting was performed in biphasic polyurethane foam blocks. In the next step, 10 SMAs and 10 industrially made anchors (IMAs; 1.8-mm double-loaded Y-Knot Flex all-suture anchor; ConMed Linvatec, Largo, FL, USA) were applied with an insertion tool and tested in fresh porcine femora using a servohydraulic testing system, with a preload of 10 N and a displacement rate of 12.5 mm/s. Pullout strength and failure mode were recorded.

RESULTS

The mean load at failure in the foam blocks was 459 ± 124 N in the SMA group and 538 ± 83 N in the IMA group. In porcine bone, failure occurred at 461 ± 102 N in the SMA group and 431 ± 135 N in the IMA group. The differences in pullout strength between the 2 types of anchor were not statistically significant, either in the foam blocks (P = .17) or in porcine bone (P = .62).

CONCLUSION

A handmade all-suture anchor using 2 high-strength sutures woven into a 2-mm strip of high-strength tape did not show statistically different failure loads in polyurethane foam or in porcine metaphyseal bone in comparison with a commercially produced double-loaded all-suture anchor. The principal mode of failure in porcine bone in both groups was anchor pullout.

Editorial Commentary: A New Star Is Born-The Knotless All-Suture Anchor

The development of all-suture anchors has revolutionized the field of orthopaedic surgery. Biomechanically, these anchors have similar or better strength when compared with conventional solid anchors. All-suture anchors allow the suture to be placed in cortical bone tunnels, with a smaller diameter, thus limiting potential iatrogenic damage. To avoid the inconsistencies of knot tying and eliminate knot stacks, knotless all-suture anchors have been increasingly used in arthroscopic surgery. This may reduce the potential risk of knot abrasion, which can lead to soft-tissue or cartilage damage. Depending on the intraoperative situation and surgeon preference, surgeons must decide whether knotted or knotless anchor systems are indicated.

The Clinical and Biomechanical Performance of All-Suture Anchors: A Systematic Review

Purpose

This systematic review aimed to clarify the relative strengths and weaknesses of the all-suture anchors (ASAs) in both clinical and experimental studies. Our hypothesis was that there would be similar clinical and experimental data for ASAs regarding the biomechanical properties, clinical outcomes and complication rates.

Methods

A systematic review of MEDLINE and Embase databases was performed. The inclusion criteria for clinical studies were both retrospective or prospective study design and minimum 1-year follow-up; for biomechanical studies, the inclusion criteria were performance on either cadaver and animal bones or synthetic surfaces. Studies were excluded if the studies were not in English or if they were review articles, commentaries, letters, case reports, or technical notes. The risk of bias assessment was done using the Methodological Index for Non-randomized Studies (MINORS) tool.

Results

We included 13 experimental and 3 clinical studies. The least displacement under cyclic loading was recorded with Q-Fix. Failure mode was mostly by suture breaking for the Q-Fix, whereas anchor pullout was the most common for the others. Cadaver humerus’ greater tuberosity seemed to be less durable for the ASAs. Tests on cadaver glenoid showed similar biomechanical properties when compared to a control anchor. Studies investigating clinical and radiologic findings were very few, and only 3 case series were included in this review. Clinical findings of patients treated with ASAs for instability and rotator cuff repair showed satisfactory results and little increase in the complication rate (retear or revision surgery because of loose anchor).

Conclusions

ASAs have similar or better biomechanical properties compared to regular anchors. Low-profile design seems to be an important advantage. Case series can not distinguish between the possible clinical benefits and/or risks.

Clinical Relevance

ASAs have similar biomechanical properties when compared with other types of anchors. Their strength and performance vary with anatomic location, which may influence clinical success.

Editorial Commentary: Innovations in Anchor Design-Are Patients Really Benefiting?

Vented open-architecture suture anchors provide theoretical benefits over traditional screw-in solid anchors to include improved osseous ingrowth, elution of marrow elements to enhance biology at the repair site, and easier revision because of reduced anchor material. However, there is no evidence that open-architecture anchors result in improvements in patient-reported outcomes or early cytokine and marrow element release into the subacromial space compared with traditional screw-in solid anchors. Although innovation and evaluation of new technologies are paramount to surgical progress, decisions on implant use should be based on factors including cost, impact on revision, and surgeon familiarity because frequently, clinical differences based on patient-reported outcomes are not appreciated between anchor types or designs.

Calcium Phosphate Bone Void Filler Increases Threaded Suture Anchor Pullout Strength: A Biomechanical Study

PURPOSE

To compare the response to cyclical loading and ultimate pull-out strength of threaded suture anchor with and without calcium phosphate bone void filler augmentation in a polyurethane foam block model and in vitro proximal humerus cadaveric model.

METHODS

This controlled biomechanical study consisted of 2 parts: (1) preliminary polyurethane foam block model, and (2) in vitro cadaveric humeri model. The preliminary foam block model intended to mimic osteoporotic bone using a 0.12 g/mL foam material. Half of the foam block models were first filled with injectable calcium phosphate bone substitute material (CP-BSM), whereas the other half were not augmented with CP-BSM. Each specimen was then instrumented with a threaded suture anchor. The same technique and process was performed in a matched cadaveric humeri model. Testing then consisted of a stepwise, increasing axial load protocol for a total of 40 cycles. If the anchor remained intact after cyclic loading, the repair was loaded to failure. The number of completed cycles, failure load, and failure modes were compared between groups.

RESULTS

Average pull-out strength for suture anchor with CP-BSM in the osteoporotic foam block model was significantly higher at 332.68 N ± 47.61 compared with the average pull-out strength of suture anchor without CP-BSM at 144.38 N ± 14.58 (P = .005). In the matched cadaveric humeri model, average pull-out strength for suture anchor with CP-BSM was significantly higher at 274.07 N ± 102.07 compared with the average pull-out strength of suture anchor without CP-BSM at 138.53 N ± 109.87 (P = .029).

CONCLUSIONS

In this time zero, biomechanical study, augmentation of osteoporotic foam block and cadaveric bone with calcium phosphate bone substitute material significantly increases pull-out strength of threaded suture anchors.

CLINICAL RELEVANCE

Considering concerns about suture anchor pull-out from osteoporotic bone, augmentation with calcium phosphate bone substitute material increases load to failure resistance.

Three anchor concepts for rotator cuff repair in standardized physiological and osteoporotic bone: a biomechanical study

BACKGROUND

Previous biomechanical studies used single-pull destructive tests in line with the anchor and are limited by a great variability of bone density of cadaver samples. To overcome these limitations, a more physiological test setting was provided using titanium, bioresorbable, and all-suture anchors.

METHODS

In this controlled laboratory study, 3 anchor constructs were divided into 2 groups: physiological and osteoporotic. Sixty standardized artificial bone specimens (=10 for each anchor in each group) were used for biomechanical testing. The anchors were inserted at a 45° angle as during surgery. Cyclic loading for 1000 cycles followed by ultimate load-to-failure (ULTF) testing was performed. Elongation, ultimate load at failure, and the mode of failure were noted.

RESULTS

In the physiological group, the ULTF for the all-suture anchor (mean [standard deviation], 632.9 [96.8 N]) was found to be significantly higher than for the other anchors (titanium, 497.1 [50.5] N, and bioresorbable, 322.4 [3.1 N], P < .0001). The titanium anchor showed a significantly higher ULTF than the bioresorbable anchor (P < .0001). In the osteoporotic group, the all-suture anchor again showed a higher ULTF compared to the bioresorbable anchor (500.9 [50.6] N vs. 315.1 [11.3] N, P < .0001). In the osteoporotic group, cyclic loading revealed a higher elongation after 1000 loading cycles for the bioresorbable (0.40 [0.12] mm) compared to the titanium (0.22 [0.11] mm; P = .01) as well as the all-suture anchor (0.19 [0.15] mm, P = .003).

CONCLUSION

Regarding ULTF, the all-suture anchor outperformed the other anchors in physiological bone, but in osteoporotic bone, significance was reached only compared to the bioresorbable anchor. Although cyclic loading revealed significant differences, these might not be clinically relevant.

Biomechanical analysis of conventional anchor revision after all-suture anchor pullout: a human cadaveric shoulder model

HYPOTHESIS AND BACKGROUND

The possibility of implanting a conventional anchor at the pullout site following all-suture anchor failure was evaluated in a biomechanical cadaveric model. The hypothesis of the study was that anchor revision would yield equal biomechanical properties.

METHODS

Ten human humeri were obtained, and bone density was determined via computed tomography. After all-suture anchor (n = 5) and conventional 4.5-mm anchor (n = 5) insertion, biomechanical testing was conducted. Following all-suture anchor pullout, a conventional 5.5-mm anchor was inserted at the exact site of pullout (n = 5) and biomechanical testing was reinitiated. Testing was conducted using an initial preload of 20 N, followed by an unlimited cyclic protocol, with a stepwise increasing force of 0.05 N for each cycle at a rate of 1 Hz until system failure. The number of cycles, maximum load to failure, stiffness, displacement, and failure mode, as well as macroscopic observation at the failure site including diameter, shape, and cortical destruction, were registered.

RESULTS

The defect following all-suture pullout showed a mean diameter of 4 mm, and conventional revision was possible in each sample. There was no significant difference between the initial all-suture anchor implantation and the conventional anchor implantation or the conventional revision following all-suture failure regarding mean pullout strength, stiffness, displacement, or total number of cycles until failure.

CONCLUSION

Conventional anchor revision at the exact same site where all-suture anchor pullout occurred is possible and exhibits similar biomechanical properties.

Conventional rotator cuff versus all-suture anchors-A biomechanical study focusing on the insertion angle in an unlimited cyclic model

PURPOSE

The purpose of this study was to compare the biomechanical properties of an all-suture anchor to a conventional anchor used commonly in rotator cuff repairs. Furthermore, the biomechanical influence of various implantation angles was evaluated in both anchor types in a human cadaveric model.

METHODS

30 humeri were allocated into three groups with a similar bone density. The two different anchor types were inserted at a predefined angle of 45°, 90° or 110°. Biomechanical testing included an initial preload of 20N followed by a cyclic protocol with a stepwise increasing force of 0,05N for each cycle at a rate of 1Hz until system failure. Number of cycles, maximum load to failure, stiffness, displacement and failure mode were determined.

RESULTS

27 anchors failed by pullout. There was no significant difference between the conventional and the all-suture anchor regarding mean pullout strength. No considerable discrepancy in stiffness or displacement could be perceived. Comparing the three implantation angles no significant difference could be observed for the all-suture or the conventional anchor.

CONCLUSION

All-suture anchors show similar biomechanical properties to conventional screw shaped anchors in an unlimited cyclic model. The exact insertion angle is not a significant predictor of failure.