Mechanical properties of all-suture anchors for rotator cuff repair

Extensor tendon rupture and preoperative mri confirmations of suture anchor prolapse: a case report and literature review

BACKGROUND

While suture anchors are widely used in medical procedures for their advantages, they can sometimes lead to complications, including anchor prolapse. This article presents a unique case of suture anchor prolapse at the base of the distal phalanx of the little finger after extensor tendon rupture reconstruction surgery.

CASE PRESENTATION

A 35-year-old male, underwent extensor tendon rupture reconstruction using a non-absorbable suture anchor. After seven years the patient visited our outpatients complaining of stiffness, pain, and protrusion at the surgical site. Initial X-ray imaging suggested suggesting either a fracture of the distal phalanx or tendon adhesion but lacked a definitive diagnosis. Subsequent magnetic resonance imaging (MRI) revealed bone connectivity between the middle and distal phalanges with irregular signal shadow and unclear boundaries while maintaining a regular finger shape. MRI proved superior in diagnosing prolapsed suture anchors, marking the first reported case of its kind. Surgical intervention confirmed MRI findings.

CONCLUSIONS

Suture anchor complications, such as prolapse, are a concern in medical practice. This case underscores the significance of MRI for accurate diagnosis and the importance of tailored surgical management in addressing this uncommon complication.

An All-Suture Anchor Offers Equivalent Clinical Performance to an Established Solid Suture Anchor in the Arthroscopic Repair of Rotator Cuff Tears: A Prospective, Randomized, Multicenter Trial With 12-Month Follow-Up

PURPOSE

To evaluate the safety and efficacy of a next-generation, all-suture anchor in patients undergoing arthroscopic repair of rotator cuff tears, compared with that of an established solid suture anchor.

METHODS

Between April 2019 and January 2021, a prospective, comparative, randomized controlled noninferiority study conducted on people with Chinese ethnicity at 3 tertiary hospitals enrolled patients (18-75 years) requiring arthroscopic treatment for rotator cuff tears. Patients were randomized into 2 cohorts receiving either all-suture anchor or solid suture anchor and followed for 12 months. The primary outcome was the Constant-Murley score at the 12-month follow-up. Magnetic resonance imaging assessments determined the rate of retear of rotator cuff repair (defined as Sugaya classification 4 and 5). Safety evaluation was performed at all follow-up points to determine the adverse events (AEs).

RESULTS

In total, 120 patients with rotator cuff tears (mean age, 58.3 years; 62.5% female; 60 receiving all-suture anchor) underwent treatment. Five patients were lost to follow-up. Both cohorts showed significant improvement in Constant-Murley scores between baseline and 6 months (P < .001) and between 6 and 12 months (P < .001). There were no significant differences in Constant-Murley scores between the 2 cohorts at 12 months (P = .122) after operation. The retear rate at 12 months was 5.7% and 1.9% in the all-suture and solid suture anchor cohorts, respectively (P = .618). There were 2 cases of intraoperative anchor pullout, both of which were successfully resolved. No cases of postoperative reoperation or other anchor-related AEs were reported.

CONCLUSIONS

The all-suture anchor offered equivalent clinical performance to an established solid suture anchor at the 12-month follow-up in patients undergoing arthroscopic repair of rotator cuff tears. The retear rate was not statistically significantly different between the 2 cohorts.

LEVEL OF EVIDENCE

Level I, randomized controlled trial.

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.

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 medial tibiofemoral joint mechanics between all-suture anchors and transtibial pullout technique for posterior medial meniscal root tears

BACKGROUND

The posterior medial meniscal root tear (PMMRT) seriously impacts the tibiofemoral joint biomechanics. Two available techniques for PMMRT repair include the transtibial pullout (TPO) repair and all-suture anchor (ASA) repair techniques. These techniques have not been compared biomechanically.

METHODS

A total of 20 fresh porcine cadaveric knee specimens were used. All 20 knees were randomly and evenly distributed into four groups (five specimens per group): (1) intact posterior meniscal root, (2) PMMRT, (3) TPO repair technique for PMMRT, and (4) ASA repair technique for PMMRT. The tibiofemoral contact mechanics were investigated using a pressure sensor. All knee specimens were tested by being loaded with 600 N axial compressive force at three different flexion angles (0°, 45°, and 90°). The contact surface area, contact pressure, peak pressure, and time-zero displacement were recorded.

RESULTS

The PMMRT caused a significant decrease in contact surface area, an increase in contact pressure, and peak pressure from the reference values observed in the intact meniscus group (P = 0.05, 0.016, and 0.008, respectively). After fixation, no significant difference was observed between the ASA and intact group. Meanwhile, significant differences were found between the TPO and intact group in terms of contact surface area, contact pressure, and peak pressure. In the comparison between the two techniques, the ASA group demonstrated higher contact surface area than the TPO group at the average knee flexion angle (p = 0.05).

CONCLUSION

For most testing conditions, the ASA technique demonstrated superior biomechanical property in terms of contact surface area compared with the TPO technique under compressive loading conditions. The ASA technique could also restore the tibiofemoral contact mechanics to be comparable with those of the native intact knee. Meanwhile, a significant difference in tibiofemoral mechanics, compared with the intact knee, could be observed in the TPO technique.

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.

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.

Mechanical mechanism of suture passer needle break in rotator cuff repair

Introduction

Suture passer needle, as one of commonly used instrument in the arthroscopic rotator cuff repair, often breaks at the notch of the needle, which originally was designed to facilitate suture with thread. Our study aimed to evaluate the suture failure rate and stitch success rate between intact suture needle and broken needle and explore the mechanism of the needle breakage and achieving better future designs.

Materials and methods

From 2017 to 2021, consecutive 437 shoulders (11 cases were bilateral) underwent arthroscopic repair for full-thickness rotator cuff tear at the authors' institution. The breakage of needles was recorded. Finite elements analysis and mechanical test were utilized to compare stress distribution, puncture performance, and loaded puncture performance between the broken needle and the intact needle.

Results

We identified 19 consecutive patients for whom the needle tip of the TruePass™ suture passer was broken in the 437 shoulder surgeries. Based on the finite element analysis of Abaqus, around the tip and the notch of the intact needle was a large stress concentration. The average puncture force required by intact needle tip and the broken tip is 61.78N and 78.23N respectively. While the intact tip with notch is easier to break than the broken tip.

Conclusions

The notch of the needle is a weak point in mechanics. The broken needle without the notch still has good tendon piercing and thread passing ability. The notch of needle may be not necessary, and the tip of the needle should be modified.

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.

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.

Transosseous repair with a cortical implant for greater tubercle cyst-related rotator cuff tear results in good clinical outcomes, but significant implant migration

PURPOSE

To evaluate whether an arthroscopic transosseous technique (ATO) with cortical implants is effective for rotator cuff tear (RCT) repair in patients with cysts of the greater tuberosity (GTC).

METHODS

Patients treated with the ATO technique between January 2013 and October 2017 were evaluated. Inclusion criteria were patients treated for both cyst-related and non-cyst-related RCTs and patients with a moderate-sized tear (1-3 cm) according to the DeOrio and Cofield classification. A total of 39 patients were separated into two groups: Group 1 (n = 16) patients with cyst-associated RCT, and Group 2 (n = 23) patients with no cyst. Implant pull-out and migration were evaluated radiologically on standard antero-posterior shoulder radiographs and rotator cuff re-tear was assessed on magnetic resonance images at the final follow-up examination. Group 1 patients were separated into two subgroups according to cyst size (cyst < 5 mm and cyst ≥ 5 mm) and subgroup analysis was performed. Clinical assessment was performed using a visual analog scale, the Constant score and Oxford shoulder score.

RESULTS

The mean follow-up time was 33.7 ± 11.7 months. The mean cyst size was 5.4 ± 1.5 mm. There was no significant difference in re-tear rates between the cystic and non-cystic groups. The mean implant migration distance was 3.0 ± 2.2 mm in patients with a RCT -related cyst and 0.7 ± 0.8 mm in those without a cyst. A statistically significant difference was found between the groups (p = 0.002). There was no statistically significant difference between the groups in respect of clinical scores. No implant failure was observed.

CONCLUSION

The ATO method performed with a cortical implant in RCTs resulted in satisfactory recovery and clinical outcomes in the short to medium term with low failure rates. While no implant failures were observed, implant migration was associated with cyst presence. Therefore, judicious use is advocated in the choice of transosseous fixation for cyst-related RCTs and patients should be informed of the possibility of implant migration.

LEVEL OF EVIDENCE

III.

Arthroscopic Posterior Labral Repair in Active-Duty Military Patients: A Reliable Solution for an At-Risk Population, Regardless of Anchor Type

BACKGROUND

Active-duty servicemembers are a population at risk for the development of posterior shoulder instability. While short-term outcomes after arthroscopic posterior labral repair for posterior shoulder instability are promising, there is a paucity of longer term follow-up data for this procedure.

PURPOSES

The primary purpose was to report midterm outcomes after arthroscopic posterior labral repair in active-duty military patients for posterior shoulder instability without bone loss. The secondary purpose was to determine if outcomes varied between anchor types used.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Preoperative and postoperative outcomes, with a minimum 3-year follow-up, for a visual analog scale for pain, the Single Assessment Numeric Evaluation (SANE), the American Shoulder and Elbow Surgeons (ASES) score, and the Rowe score were collected and analyzed. A separate subgroup analysis was performed comparing the outcomes of patients who underwent repair with biocomposite anchors versus those who underwent repair with all-suture anchors.

RESULTS

A total of 73 patients with a mean follow-up of 82.55 ± 24.20 months met the inclusion criteria and were available for analysis. As a whole, the cohort demonstrated statistically and clinically significant improvements in outcome scores at final follow-up. Preoperative and postoperative range of motion did not vary significantly. While the difference in final outcome scores between the 2 anchor types did not reach statistical significance, a statistically significantly larger proportion of patients who underwent repair with all-suture anchors versus those who underwent repair with biocomposite anchors met the Patient Acceptable Symptom State for the SANE (97.14% vs 78.95%, respectively; P = .0180) and the ASES score (88.57% vs 68.42%, respectively; P = .0171). The proportion of patients who achieved the substantial clinical benefit or surpassed the minimal clinically important difference, however, did not vary by anchor type. Overall, 70 patients (95.89%) remained on active duty and were able to return to preinjury work and recreational activity levels. There were 3 patients (4.11%) who had recurrent posterior instability.

CONCLUSION

This population of active-duty servicemembers undergoing posterior labral repair for posterior labral instability without bone loss demonstrated a statistically and clinically significant improvement in midterm outcomes, a low recurrence rate, and a rate of return to active duty of 95.89%, regardless of the anchor type used.

Perianchor Cyst Formation Is Similar Between All-Suture and Conventional Suture Anchors Used for Arthroscopic Rotator Cuff Repair in the Same Shoulder

Purpose

The purpose of this study was to compare perianchor cyst formation between soft and hard suture anchors placed in the same patient 1 year after arthroscopic rotator cuff repair (ARCR).

Methods

This study reviewed patients who underwent primary ARCR using a “hybrid” technique using at least one soft anchor (FiberTak, Arthrex, Naples, FL) and one hard anchor (SwiveLock) placed in the same shoulder between January 1, 2018 and December 31, 2018. Magnetic resonance imaging was obtained at minimum 1-year postoperative to assess cyst formation (perianchor fluid signal) and rotator cuff healing. Range of motion (ROM) and patient-reported outcome measures (PROMs) were evaluated at baseline and 1-year follow up. PROMs included visual analog scale pain score, Simple Shoulder Test score, American Shoulder and Elbow Surgeon (ASES) score.

Results

Nineteen patients with a combined 45 hard and 26 soft suture anchors were available for follow-up at a mean of 20 months postoperatively. There was a higher proportion of grade 1 fluid signal changes in the hard anchor group compared to the soft group (62.2% to 7.7; P < .001); however, there was no difference in the incidence of cyst formation (grade 2 or 3 changes) between groups (13.3% vs 3.8%; P = .251). There was also no difference in the rate of cyst formation between biocomposite and polyether-ether-ketone-type hard anchors (18.2% vs 0%; P = .113) or between anchors placed at the greater and lesser tuberosities (10.2% vs 5.3%, P = .519).

Conclusion

Hard suture anchors showed increased fluid signal compared to soft suture anchors at short-term follow-up after ARCR, but there was no difference in cyst formation between anchor types.

Biomechanical properties of a suture anchor system from human allogenic mineralized cortical bone matrix for rotator cuff repair

Background

Suture anchors (SAs) made of human allogenic mineralized cortical bone matrix are among the newest developments in orthopaedic and trauma surgery. Biomechanical properties of an allogenic mineralized suture anchor (AMSA) are not investigated until now. The primary objective was the biomechanical investigation of AMSA and comparing it to a metallic suture anchor (MSA) and a bioabsorbable suture anchor (BSA) placed at the greater tuberosity of the humeral head of cadaver humeri. Additionally, we assessed the biomechanical properties of the SAs with bone microarchitecture parameters.

Methods

First, bone microarchitecture of 12 fresh frozen human cadaver humeri from six donors was analyzed by high-resolution peripheral quantitative computed tomography. In total, 18 AMSAs, 9 MSAs, and 9 BSAs were implanted at a 60° angle. All three SA systems were systematically implanted alternating in three positions within the greater tuberosity (position 1: anterior, position 2: central, position 3: posterior) with a distance of 15 mm to each other. Biomechanical load to failure was measured in a uniaxial direction at 135°.

Results

Mean age of all specimens was 53.6 ± 9.1 years. For all bone microarchitecture measurements, linear regression slope estimates were negative which implies decreasing values with increasing age of specimens. Positioning of all three SA systems at the greater tuberosity was equally distributed (p = 0.827). Mean load to failure rates were higher for AMSA compared to MSA and BSA without reaching statistical significance between the groups (p = 0.427). Anchor displacement was comparable for all three SA systems, while there were significant differences regarding failure mode between all three SA systems (p < 0.001). Maximum load to failure was reached in all cases for AMSA, in 44.4% for MSA, and in 55.6% for BSA. Suture tear was observed in 55.6% for MSA and in 22.2% for BSA. Anchor breakage was solely seen for BSA (22.2%). No correlations were observed between bone microarchitecture parameters and load to failure rates of all three suture anchor systems.

Conclusions

The AMSA showed promising biomechanical properties for initial fixation strength for RCR. Since reduced BMD is an important issue for patients with chronic rotator cuff lesions, the AMSA is an interesting alternative to MSA and BSA. Also, the AMSA could improve healing of the enthesis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-022-05371-0.

All-Suture Anchors in Orthopaedic Surgery: Design, Rationale, Biomechanical Data, and Clinical Outcomes

All-suture anchors (ASAs) are a relatively new alternative to traditional suture anchors, comprised of sutures, suture tapes, or ribbons woven through a soft sleeve. These novel anchors are typically smaller than traditional anchors, allowing for more anchors to be used in the same amount of space or for use when bone stock is limited, for example, in revision settings. They can be inserted through curved guides to reach more challenging locations, and they have thus far had similar loads to failure during biomechanical testing as traditional anchors. However, these benefits must be weighed against new challenges. When using ASAs, care must be taken to fully deploy and seat the anchor against cortical bone for optimal fixation and to prevent gap formation. Furthermore, decortication, often performed to enhance the biologic environment for soft-tissue healing, may weaken the cortical bone on which ASA fixation depends on. The purpose of this article is to provide insight on the designs, advantages, and potential disadvantages associated with ASAs, as well as review the available biomechanical and clinical data.

Trabecular Bone Score Could Not Predict the Bone Mineral Density of Proximal Humerus

Background

Osteoporosis is an important clinical factor for tendon healing after arthroscopic rotator cuff repair (ARCR). Conventional dual energy X-ray absorptiometry (DXA) of the hip and lumbar spine (LS) does not represent proximal humeral bone mineral density (BMD). Theoretically, direct measurement of the BMD of the proximal humerus is the best method; however, it is not popular and is non-standardized. Therefore, we evaluate whether the trabecular bone score (TBS) using LS DXA would represent proximal humeral BMD.

Methods

Conventional hip and LS DXA and proximal humeral BMD were measured in 212 consecutive ARCR patients, and TBS was calculated using LS DXA. Comparative analysis between the affected and contralateral asymptomatic shoulders was done; moreover, correlation analysis was conducted to evaluate the representativity of TBS for proximal humeral BMD. Regression analysis was performed to elucidate the risk factor of intraoperative suture anchor failure (ISAF).

Results

BMDs of the affected shoulder were significantly lower than those of the contralateral side (all P<0.05). TBS failed to present a strong correlation with proximal humeral BMD (correlation coefficients 0.155–0.506, all P<0.05), and the BMD of the greater tuberosity (GT) of the proximal humerus was revealed to be a sole risk factor for ISAF (odds ratio, 0.01, P=0.020).

Conclusions

TBS and conventional hip and LS DXA did not represent proximal humeral BMD. Furthermore, among the various radiological measurements, the BMD of the GT was a sole risk factor of ISAF. Therefore, further research for the direct measurement of proximal humeral BMD is mandatory to predict proximal humeral focal osteoporosis.

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.

Comparison of Hook Plate Fixation Versus Arthroscopic Coracoclavicular Fixation Using Multiple Soft Anchor Knots for the Treatment of Acute High-Grade Acromioclavicular Joint Dislocations

PURPOSE

To compare the clinical and radiologic outcomes of arthroscopically assisted coracoclavicular (CC) fixation using multiple soft anchor knots versus hook plate fixation in patients with acute high-grade Rockwood type III and V acromioclavicular (AC) joint dislocations.

METHODS

This retrospective study included 22 patients with acute Rockwood type III and V AC joint dislocations who underwent arthroscopic fixation or hook plate fixation surgery between February 2016 and March 2018. Patients were categorized into 2 groups: arthroscopically assisted CC fixation using multiple soft anchor knots group (AR, n = 12) and hook plate fixation group (HO, n = 10). We measured the CC distances (CCDs) and CCD ratio at 6 months, 1 year, and last follow-up postoperatively to compare the radiologic results between the groups. Clinical outcomes were assessed at 1 year postoperatively and at the last follow-up using the Visual Analog Scale, American Shoulder and Elbow Surgeons (ASES) scores, and Shoulder Pain and Disability Index (SPADI) scores, and the Disabilities of the Arm, Shoulder, and Hand (DASH) questionnaire. Magnetic resonance imaging after hook plate removal was used to evaluate the healing ligaments and tendon-bone interface.

RESULTS

The patients in the AR group had better ASES, SPADI, and Quick DASH scores than the patients in the HO group at 1 year postoperatively and at last follow-up. The CCD and CCD ratio were significantly better in the AR group than in the HO group at the last follow-up period (P = .007/0.029). Magnetic resonance imaging findings showed grade I in 60% of patients in the AR group and grade III in 60% of patients in the HO group. AC joint arthritic change was observed in 40% of the HO group.

CONCLUSIONS

The CC fixation method using multiple soft anchor knots showed satisfactory results and had superior CC ligament healing ability and maintenance of CCD than hook fixation.

LEVEL OF EVIDENCE

Level III, retrospective therapeutic comparative investigation.

Surgical Repair of Distal Biceps Femoris Avulsion Injuries in Professional Athletes

Background

Understanding the optimal management of distal biceps femoris avulsion injuries is critical for restoring preinjury function, restoring hamstring muscle strength, increasing range of motion, and minimizing risk of complications and recurrence. Due to the rarity of these injuries, prognosis and outcomes within the literature are limited to case reports and small case series.

Purpose

To assess the effect of surgical repair for acute distal avulsion injuries of the biceps femoris tendon on (1) return to preinjury level of sporting function and (2) time to return to preinjury level of sporting function, patient satisfaction, and complications.

Study Design

Case series; Level of evidence, 4.

Methods

This prospective single-surgeon study included 22 elite athletes (18 men [82%], 4 women [18%]; mean age, 26 years; age range, 17-35 years; mean body mass index, 25.3 ± 4.1 kg/m²) undergoing primary suture anchor repair of avulsion injuries of the distal biceps femoris confirmed on preoperative magnetic resonance imaging. Predefined outcomes relating to time for return to sporting activity, patient satisfaction, complications, and injury recurrence were recorded at regular intervals after surgery. Minimum follow-up time was 12 months (range, 12.0-26.0 months) from the date of surgery.

Results

The mean time from injury to surgical intervention was 12 days (range, 2-28 days). All study patients returned to their preinjury level of sporting activity, predominately professional soccer or rugby. Mean time from surgical intervention to return to full sporting activity was 16.7 ± 8.7 weeks. At 1- and 2-year follow-up, all study patients were still participating at their preinjury level of sporting activity. There was no incidence of primary injury recurrence, and no patients required further operation to the biceps origin.

Conclusion

Surgical repair of acute avulsion injuries of the distal biceps femoris facilitated early return to preinjury level of function with low risk of recurrence, low complication rate, and high patient satisfaction in elite athletes. Suture anchor repair of these injuries should be considered a reliable treatment option in athletes with high functional demands to permit an early return to sport with restoration of hamstring strength.

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.

Posterior Shoulder Instability: The Augmented McLaughlin Procedure

Posterior shoulder dislocation, whilst uncommon, is frequently missed and often associated with a significant defect on the antero-medial aspect of the humeral head (the reverse Hill-Sachs lesion). Several techniques for stabilisation have been described, depending on the size of the lesion. We describe an additional technique for stabilising the shoulder following posterior dislocation by augmenting the reverse Hill-Sachs lesion with layers of extracellular matrix, thus further filling the defect.

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.

Editorial Commentary: What is the Difference That Makes the Differences? The Practical Rationality of the All-Suture Anchor

Suture anchor technologies are constantly being innovated in the quest for improved stability, biological integration and clinical outcomes. However, the decision about the choice of suture-anchor materials remain elusive. There are some factors, including reliability, effectiveness, simplicity, familiarity, and cost, that affect a surgeon's preference. The relative weights placed on different factors by different surgeons play decisive roles in individual choice. But decisions and choices are not arbitrary or merely subjective. Alternative options can be warranted or contested by rational argumentation. At the end, there may be losses and gains in the change of 1 suture anchor for another, but science does progress.

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.

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.

A Biomechanical Comparison of Different Suture Materials Used for Arthroscopic Shoulder Procedures

PURPOSE

To evaluate the viscoelastic properties of 4 commercially available cord-like sutures and 2 commercially available suture tapes when subjected to physiological loads, as well as to compare them with each other and to identify the clinically most desirable combination of suture material properties.

METHODS

Six suture materials (Ethibond, FiberWire, FiberTape, Orthocord, Ultrabraid, and Ultratape) underwent creep testing (n = 7, 60 N, 10 minutes) to determine specimen stiffness, initial elongation at 60 N of load, static creep (during 10 minutes of loading), and relaxed elongation (material recovery 3 minutes after removal of load). Furthermore, cyclic testing (n = 7, 10-45 N, 0.5 Hz, 500 cycles) was carried out to determine dynamic creep, peak-to-peak displacement, and relaxed elongation. Mechanical testing was conducted on a material testing machine in 37°C phosphate-buffered saline solution.

RESULTS

FiberTape showed the greatest stiffness (23.9 ± 3.2 N/mm, P < .001), the smallest amounts of static (0.38 ± 0.10 mm, P < .001) and dynamic (0.16 ± 0.09 mm, P = .003) creep, and the smallest peak-to-peak displacement (0.20 ± 0.02 mm, P < .001). FiberTape and FiberWire showed the smallest initial elongation (1.17 ± 0.17 mm and 1.63 ± 0.25 mm, respectively; P < .001). Ultrabraid showed the greatest relaxed elongation, both statically (4.73 ± 0.73 mm, P < .001) and dynamically (4.18 ± 0.83 mm, P = .002).

CONCLUSIONS

FiberTape consistently displayed less creep, greater stiffness, and less extensibility than the other suture types. Ultrabraid showed the largest amount of relaxed elongation on both static and dynamic testing.

CLINICAL RELEVANCE

When considering high stiffness in combination with low initial extension and low static creep to be ideal parameters to achieve optimal initial construct stability and considering low dynamic creep in combination with low peak-to-peak displacement to be ideal conditions for the repetitive loading of the construct during the healing process, tapes seem to be superior to cord-like sutures for performing rotator cuff repair.

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.

The formation of perianchor fluid associated with various suture anchors used in rotator cuff repair

Aims

The aim of this study was to compare the osseous reactions elicited by all-suture, polyetheretherketone (PEEK), and two different biodegradable anchors used during rotator cuff repair.

Patients and Methods

Transosseous-equivalent rotator cuff repair was performed in 73 patients. The patients were divided into two groups, in both of which two different medial-row anchors were used. In group 1, anchor A comprised 30% β-tricalcium phosphate (TCP) + 70% fast-absorbing poly lactic-co-glycolic acid copolymer (85% polylactic acid enantiomers + 15% polyglycolic acid) and anchor B comprised all-sutures. In group 2, anchor C comprised 23% micro β-TCP + 77% polylactic acid enantiomers and anchor D comprised PEEK polymer. There were 37 patients in group 1 and 36 patients in group 2. The presence and severity of fluid collection around anchors and healing of the rotator cuff were assessed using MRI scans, approximately one year postoperatively. The severity of the collection was graded as 0 (no perianchor fluid signal), 1 (minimal perianchor fluid), 2 (local collection of fluid), 3 (fluid collection around the whole length of the anchor but of a diameter less than twice the anchor diameter), or 4 (fluid collection around the whole length of the anchor and of a diameter greater than twice the anchor diameter).

Results

A perianchor fluid signal was seen in three patients (8.1%) with anchor A, four (10.8%) with anchor B, 15 (41.7%) with anchor C, and 15 (41.7%) with anchor D. The severity of the collection around anchor was grade 2:1:0:0 for anchor A, grade 2:2:0:0 for anchor B, grade 12:2:0:1 for anchor C, and grade 11:3:0:1 for anchor D (grade 1:2:3:4, respectively). The prevalence and severity of fluid formation was not significantly different between anchors A and B, and anchors C and D. However, on intergroup analysis, there were significant differences for the prevalence and severity of fluid formation between anchors in group 1 and group 2. The prevalence of failure to heal was not significant in group 1 (seven, 18.9%) or group 2 (nine, 25.0%). There was no relationship between the presence of perianchor fluid and each type of anchor, and the integrity of the rotator cuff repair, in either group.

Conclusion

Despite the nonabsorbable nature of all-suture and PEEK anchors, all-suture anchors produced less osseous reaction after rotator cuff repair. In deciding which kind of anchor to use, consideration should be given not only to the strength of the initial fixation, but also to the postoperative biological reaction. Cite this article: Bone Joint J 2019;101-B:1506–1511

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.

Biomechanical testing of trans-humeral all-suture anchors for rotator cuff repair

BACKGROUND

Rotator cuff tears are one of the most common causes of shoulder pain. All-suture anchors are increasingly being used in the arthroscopic repair of rotator cuff tears. The purpose of this experimental study is to evaluate the biomechanical properties of all-suture anchors at different insertion sites in the proximal humerus relevant to rotator cuff repairs and the remplissage procedure.

METHODS

Sixteen cadaveric shoulders were used for the study. Four all-suture anchors were inserted in each proximal humerus at common anchor insertion sites on the rotator cuff footprint and a simulated Hill-Sachs defect. Cyclic loading and load-to-failure tests were undertaken. The number of cycles, load to failure and nature of failure were recorded.

RESULTS

The all-suture anchors placed in the cuff footprint using a transosseous technique displayed superior biomechanical properties. Sutures sited in this way demonstrated a maximum tensile load to failure of 542 N as well as a highest mean load to failure and the maximum number of cycles before anchor failure. In descending order, all-suture anchors placed in the lateral footprint were significantly superior to those located in the medial row and in a simulated Hill-Sachs defect.

DISCUSSION

Anchors placed in the rotator cuff footprint exceeded the physiological isometric abduction forces for the supraspinatus and infraspinatus. Data obtained from our study suggest that all-suture anchors are strong enough to be used for the repair of rotator cuff tears.

What Makes Suture Anchor Use Safe in Hip Arthroscopy? A Systematic Review of Techniques and Safety Profile

PURPOSE

To perform a systematic review that assesses the current literature on suture anchor placement for the purpose of identifying factors that lead to suture anchor perforation and techniques that reduce the likelihood of complications. It was hypothesized that suture anchor placement in hip arthroscopy would generally be safe, with the exception of the complications of articular cartilage violation and psoas tunnel perforation. Perioperative factors, related to patient, surgeon, and technical variables, may influence the safety of suture anchor insertion.

METHODS

Three databases (PubMed, Ovid MEDLINE, and Embase) were searched, and 2 reviewers independently screened the resulting literature. The inclusion criteria were clinical and biomechanical studies examining the use of suture anchors in hip arthroscopy. The methodologic quality of all included articles was assessed using the Methodological Index for Non-Randomized Studies criteria and the Cochrane risk-of-bias assessment tool. Results are presented according to PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines using descriptive statistics.

RESULTS

We included 14 studies in this review, comprising 4 case series (491 patients; 56.6% female patients; mean age, 33.9 years), 9 controlled cadaveric or laboratory studies (111 cadaveric hips and 12 synthetic acetabular bone blocks; 42.2% female hips; mean age, 60.0 years) with a mean Quality Appraisal for Cadaveric Studies score of 11, and 1 randomized controlled trial (37 hips; 55.6% female hips; mean age, 34.2 years). Anterior cortical perforation into the psoas tunnel by suture anchors led to pain and impingement of pelvic neurovascular structures. The anterior acetabular positions (3- to 4-o'clock position) had the thinnest bone, smallest rim angles, and highest incidence of articular perforation. Drilling angles from 10° to 20° measured off the coronal plane were acceptable. The midanterior and distal anterolateral portals were used successfully, with 1 study reporting difficulty placing anchors at anterior locations through the distal anterolateral portal. One study showed that curved suture anchor drill guides allow for a better trajectory away from the articular cartilage. Small-diameter (≤1.8-mm) all-suture anchors had a lower in vivo incidence of articular perforation with similar stability and pullout strength to other anchor types in biomechanical studies.

CONCLUSIONS

Suture anchors at anterior acetabular rim positions (3- to 4-o'clock position) should be inserted with caution. Large-diameter (≥2.3-mm) suture anchors increase the likelihood of articular perforation without increasing labral stability. Inserting small-diameter (≤1.8-mm) all-suture anchors from 10° to 20° drilling angles may increase safe insertion angles from all cutaneous portals. Direct arthroscopic visualization, the use of fluoroscopy, distal-proximal insertion, and the use of nitinol wire can help prevent articular violation.

LEVEL OF EVIDENCE

Level IV, systematic review of Level I to IV studies.

Arthroscopic Coracoclavicular Fixation Using Multiple Low-Profile Devices in Acute Acromioclavicular Joint Dislocation

PURPOSE

To introduce an arthroscopically assisted coracoclavicular (CC) fixation technique using multiple low-profile devices to evaluate the clinical and radiologic outcomes in patients with acute high-grade acromioclavicular (AC) joint dislocation.

METHODS

Between July 2014 and September 2015, cases of AC joint dislocation that were treated with arthroscopic CC fixation using multiple low-profile devices with a minimum follow-up of 24 months were included. We measured the vertical coracoclavicular distance (CCD) on the anteroposterior view and the horizontal acromioclavicular distance on 3-dimensional computed tomography images to evaluate the changes in radiologic outcomes before and after surgery. We compared final radiologic outcomes between initial AC reduction groups based on hierarchical clustering. Clinical outcomes were evaluated using the Constant-Murley score.

RESULTS

We enrolled 27 patients in total, and the mean follow-up period was 27.2 months. The mean CCD of the injured shoulder was 13.68 ± 3.98 mm preoperatively and decreased to 5.72 ± 1.68 mm immediately postoperatively but increased to 7.32 ± 2.29 mm at last follow-up (P = .07). Horizontal displacement of the distal clavicle was 1.1 ± 1.0 mm immediately postoperatively but decreased to 0.9 ± 0.6 mm at last follow-up (P < .05). In particular, in the 2 groups that were determined using the hierarchical cluster analysis, patients with excellent recovery of the initial CCD (20 patients) showed less of an increase in the CCD at last follow-up than did those in the other group (7 patients) (P < .001). The Constant-Murley score was 93.5 ± 2.7 points on the injured side at last follow-up (P = .074).

CONCLUSIONS

Our CC fixation technique with multiple low-profile devices exhibited satisfactory clinical and radiologic outcomes. In particular, ensuring good initial recovery of the CCD and the precise placement and location of the AC joints was important in maintaining the proper AC position at the final follow-up.

LEVEL OF EVIDENCE

Level IV, case series.

Does having a rotator cuff repair prior to reverse total shoulder arthroplasty influence the outcome?

Aims

The number of rotator cuff repairs that are undertaken is increasing. Reverse shoulder arthroplasty (RSA) is the procedure of choice for patients with rotator cuff arthropathy. We sought to determine whether patients who underwent rotator cuff repair and subsequent RSA had different outcomes compared with a matched control group who underwent RSA without a previous rotator cuff repair.

Patients and Methods

All patients with a history of rotator cuff repair who underwent RSA between 2000 and 2015 with a minimum follow-up of two years were eligible for inclusion as the study group. Outcomes, including the American Shoulder and Elbow Surgeons (ASES) scores, were compared with a matched control group of patients who underwent RSA without having previously undergone rotator cuff repair.

Results

The study group included 45 patients. Their mean age was 69 years (sd 8.6) and 27 patients (60%) were women. The mean ASES score improved from 43.1 to 76.6 two years postoperatively, and to 66.9 five years postoperatively. There was no significant difference between the outcomes at two years in the two groups (all p ≥ 0.05), although there was significantly more improvement in ASES scores in the control group (44.5 vs 33.4; p = 0.01). However, there was no significant difference between ASES scores at two and five years when baseline ASES scores were matched in the two groups (p = 0.42 at two years; p = 0.35 at five years).

Conclusion

Significant improvements in ASES scores were seen following RSA in patients who had previously undergone rotator cuff repair. They had higher baseline ASES scores than those who had not previously undergone this surgery. However, there was no significant difference in outcomes between the two groups, two years postoperatively. Previous rotator cuff repair does not appear to affect the early outcome after RSA adversely.

Pullout Strength of All-Suture Anchors: Effect of the Insertion and Traction Angle-A Biomechanical Study

PURPOSE

To evaluate the pullout strength of the all-suture anchor (ASA), based on the angles of anchor insertion and traction.

METHODS

Synthetic saw bones of 2 densities (0.16 and 0.32 g/cm³) with 3 mm thick cortical bone models were used. ASAs were inserted at 45°, 60°, 75°, or 90° and pulled at 2 angles from the surface: 45° (simulating the physiological pull of the supraspinatus) and 90° (simulating pulling out during knot tying). Five consecutive pullout tests for each insertion and traction angle combination per saw bone were conducted to evaluate the ultimate load to failure and mode of failure (80 tests total). Thereafter, 9 matched pairs of human cadaveric humeri with 2 ASA types were used (insertion angles, 45°, 75°, 90°; traction angle, 90°). Nine consecutive tests were conducted for each insertion angle and anchor type (54 tests total).

RESULTS

The pullout strength was significantly higher for high density- than for low-density saw bones (all P < .05). The pullout strength was higher at the 45°than at the 90° traction angle (all P < .05) and was significantly higher at the 90° and 75° than at the 45° insertion angle in both high-density saw bones and cadaveric humeri (all P < .05). However, the pullout strength was not significantly different by ASA type (all P > .05).

CONCLUSIONS

ASA showed stronger pullout strength in higher density bones. Furthermore, it presented stronger pullout strength in the physiological traction direction of supraspinatus rather than in the knot-tying direction, consistent with the deadman theory. However, stronger pullout strength was observed in the vertically directed insertion angle, not 45°. Therefore, implanting the ASA vertically may be clinically more beneficial not only when performing knot tying during surgery, but also when the supraspinatus tendon loads the ASA postoperatively.

CLINICAL RELEVANCE

The study provides biomechanical evidence that the optimal insertion angle for an ASA is more vertical than the 45°.

Greater Tuberosity Decortication Decreases Load to Failure of All-Suture Anchor Constructs in Rotator Cuff Repair

PURPOSE

To evaluate the effect of greater tuberosity decortication on ultimate load to failure and displacement after cyclic loading with an all-suture anchor.

METHODS

A 2.9-mm all-suture anchor was evaluated in decorticated and nondecorticated greater tuberosities of 10 matched pairs of human cadaveric shoulders. Greater tuberosity decortication was performed to a mean depth of 1.7 mm. Anchors were placed in the anterior, middle, and posterior tuberosity. Anchors were tested under cyclic loads followed by load-to-failure testing. Displacement after 20, 100, and 200 cycles and ultimate failure strength were determined. Clinical failure was defined as displacement greater than 5 mm during cyclic loading.

RESULTS

After 20 and 100 cycles, there was no difference in mean displacement between the decorticated and nondecorticated cohorts (P = .139 and P = .127, respectively). The mean displacement after 200 cycles was greater in the decorticated cohort, although not significantly (3.4 vs 2.7 mm; P = .05). The mean ultimate load to failure was significantly lower in the decorticated cohort (314 vs 386 N, P = .049). There were 2 clinical failures in the decorticated specimens and 1 in the nondecorticated specimens.

CONCLUSIONS

A minimal greater tuberosity decortication significantly decreases the ultimate load to failure of an all-suture anchor. However, decreased biomechanical strength may not necessitate actual clinical failure.

CLINICAL RELEVANCE

A decrease in ultimate load to failure could increase the risk of catastrophic postoperative anchor failure. However, while this decrease in strength is statistically significant, the overall decrease in strength may not be sufficient in magnitude to translate to clinical failure.

The Effect of Three Different Suture Anchors for Rotator Cuff Repair on Primary Cultures of Human Bone Marrow Mesenchymal Stem Cells

Purpose  The purpose of this study is to investigate the in vitro biocompatibility of three different suture anchors (all-suture anchor, metal anchor, and polyetheretherketone anchor), commonly used for the rotator cuff repair. Methods  To assess the biocompatibility of the anchors, the possible cytotoxicity and the immunogenicity of the devices were assessed by cell viability assay and cell count on cultures of bone marrow stem cells (BMSCs) and peripheral blood leucocytes (PBLs), respectively. The possible inhibitory effect of the devices on BMSCs osteogenic potential was evaluated by alkaline phosphatase activity and matrix deposition assay. Results  The viability of BMSCs was slightly reduced when cultured in the presence of the devices (-24 ± 3%). Nevertheless, they were able to differentiate toward the osteogenic lineage in all culture conditions. The proliferation of PBLs and the production of interleukin-2 were not enhanced by the presence of any device. Conclusion  The analyzed devices did not significantly affect the normal cells functions when directly cultured with human primary BMSCs or PBLs, in terms of osteogenic differentiation and inflammatory reaction. Clinical Relevance  A deeper knowledge of the biological reactions to different devices used in rotator cuff surgeries would improve the clinical outcome of these procedures.

Shoulder Instability: Common Problems and Solutions

Operative treatment of the unstable shoulder historically has a high success rate. However, the complication rate has risen. This article reviews the pearls and pitfalls to attempt to elucidate the etiology for these complications and failures. Preoperative assessment of the unstable shoulder ultimately is critical to avoid complications, including history, physical examination, and key radiographic features. Intraoperative techniques include appropriate soft tissue mobilization, multiple points of fixation, avoidance of hardware-related problems, and appropriate management of the capsule and bone defects. Finally, postoperative rehabilitation is equally important to regain physiologic range of motion in a safe, supervised fashion.

A hydroxamic acid–methacrylated collagen conjugate for the modulation of inflammation-related MMP upregulation

The selective covalent coupling of hydroxamic acid functions on to methacrylated type I collagen led to UV-cured networks with inherent MMP-modulating capability and enhanced proteolytic stability.

Subacromial corticosteroid injections transiently decrease suture anchor pullout strength: biomechanical studies in rats

BACKGROUND

Arthroscopic rotator cuff (RC) repair incorporates suture anchors to secure torn RC tendons to the greater tuberosity (GT) bone. RC repair strength depends on the anchor-bone interface and on the quality of the GT. We evaluated the effect of single and multiple corticosteroid injections on the pullout strength of suture anchors.

METHODS

Fifty rats were divided into those receiving saline solution injection (control group), a single methylprednisolone acetate (MTA) injection (MTA1 group), or 3 once-weekly MTA injections (MTA3 group). Rats were killed humanely at 1 or 4 weeks after the last injection. A mini-suture anchor was inserted into the humeral head through the GT. Specimens were tested biomechanically.

RESULTS

At 1 week after the last injection, the mean maximal pullout strength was significantly reduced in the MTA1 group (63.5%) and MTA3 group (56%) compared with the control group (P < .05 for both). Mean stiffness decreased significantly in both treatment groups compared with controls (P < .05). At 4 weeks after the last injection, there was a significant increase in the mean maximal pullout strength after single and triple MTA injections compared with values recorded at the 1-week time point (P < .05). At 4 weeks, the mean maximal pullout strength after a single MTA injection was 92.8% of the pullout strength measured in the control group.

CONCLUSIONS

We showed a significant detrimental effect of corticosteroid exposure on the pullout strength of a suture anchor at 1 week. However, this effect was transient and resolved within a relatively short period. These findings indicate that a waiting period is required between subacromial corticosteroid injection and RC repair surgery that involves the use of suture anchors.