Pull-out stability of anchors for rotator cuff repair is also increased by bio-absorbable augmentation: a cadaver study

Comparison of All-Suture Anchors and Metal Anchors in Arthroscopic Rotator Cuff Repair: Short-Term Clinical Outcomes and Anchor Pullout Risk

Objectives: Metal anchors (MA), commonly used in the early stages of rotator cuff surgical treatment development, are associated with a high risk of complications, especially in osteoporotic bone. As an alternative to rigid anchors, all-suture anchors (ASA) have been introduced for the medial row, offering promising clinical outcomes and favorable biomechanical studies. We aimed to compare the clinical outcomes of MAs and ASAs in either single-row or in medial-row suture bridge techniques in arthroscopic rotator cuff repair. Our hypothesis was that in cases where ASA was used for at least 12 months of follow-up, more favorable results would be obtained as compared to rigid anchors, and intraoperative complications such as anchor pullout would be encountered less. Methods: In this retrospective cohort analysis, we reviewed patients who underwent arthroscopic rotator cuff repair between January 2020 and December 2022. Surgeries were performed by two senior surgeons in a single tertiary center. Patients who had undergone revision surgery, had a history of previous shoulder surgeries, had massive rotator cuff tears, and partial-thickness tears; or had concomitant subscapularis tears were excluded. Preoperative and postoperative scores, including Constant-Murley (CM), Disabilities of the Arm, Shoulder, and Hand (DASH), and visual analog scale (VAS), were compared. The minimum follow-up period was 12 months. Clinical assessment of shoulder range of motion included forward flexion, abduction, internal rotation, and external rotation. Intraoperative anchor-related complications were compared. All patients underwent the same surgical technique and postoperative rehabilitation protocol. Results: A total of 142 patients (89 females, 53 males; mean age: 57.4 years) were included in the study, with 67 patients in the ASA group and 75 in the MA group. The sex distribution and mean age were similar between groups. The ASA group had 15 traumatic tears, while the MA group had 13 (p < 0.05). The mean follow-up period was 21.6 months (range 12-40 months). Preoperative CM scores were statistically better in the ASA group, but this difference was not clinically relevant (p < 0.046). The mean CM score was 75.64, the mean DASH score was 8.57, and the mean VAS was 1.38 at the postoperative period in the MA group. The mean CM score was 78.40, the mean DASH score was 9.75, and VAS was 1.59 at the postoperative period in the ASA group. Seven cases experienced anchor pullout in the MA group, and thread breakage occurred in one patient of each group (p = 0.014). The mean age of the patients with anchor pullout was significantly higher (p = 0.002). This finding was not hypothesized in the initial study design but emerged during post-hoc analysis and highlights the importance of considering bone quality in elderly patients. Conclusions: The clinical outcomes of rotator cuff repairs using all-suture anchors or metal anchors are comparable. However, ASA use may offer an advantage in elderly patients by reducing the risk of anchor pullout. Further studies assessing tendon integrity and bone quality and incorporating long-term follow-up periods are recommended to support and validate the present findings.

Challenges Posed by Osteoporosis in Arthroscopy and Sports Injury Management

Background

Osteoporosis, whether generalized or localized, presents significant challenges in arthroscopic procedures, particularly in surgeries such as ligament reconstructions and rotator cuff repairs, which depend on fixation through interference screws and/or anchors. These challenges are especially pronounced in women, the elderly, and individuals with chronic injuries. The literature discusses various techniques to mitigate these issues.

Objective

Despite the recognition of these challenges, there is no clear consensus on the most effective methods to address them. Current literature lacks comprehensive information on the specific difficulties surgeons encounter when managing sports injuries in osteoporotic bones, particularly around the knee. This manuscript aims to outline and describe various treatment strategies to manage sports injuries in patients with osteoporotic bones.

Current Knowledge

Numerous studies acknowledge the heightened risk of fixation failure in osteoporotic bones. Surgeons have described various techniques to address these fixation issues, such as alternative fixation methods, preserved insertion techniques, bone bridge techniques, larger diameter screws, and supplementary fixation strategies. Techniques such as transosseous equivalent (TOE) repair, special suture configurations, multiple fixation points, medial anchor placement in subchondral bone, and bone cement augmentation are among the methods used to improve anchor fixation in osteoporotic bone.

Literature Gap

Although multiple surgical techniques are available for graft and tendon fixation in osteoporotic bones, there is no clear guideline on which method offers the best combination of biological and mechanical superiority. This article reviews the various fixation techniques and explores innovative approaches to graft fixation. In addition, the authors emphasize the importance of medical management of osteoporosis in patients undergoing surgical interventions, highlighting the role of bisphosphonate, teriparatide, denosumab. Medical therapy not only reduces the risk of fixation failure but also plays a crucial role in post-operative recovery.

Conclusions

With the growing emphasis on healthy lifestyles, increasing numbers of elderly patients are participating in sports activities. As a result, more patients with low bone mineral density (BMD) are seeking treatment for sports injuries. Anticipating the issue of regional low BMD is essential, even in younger patients, to ensure that alternative fixation techniques are employed when necessary.

Enhancing Rotator Cuff Repair in Rabbit Osteoporosis With Chitosan Quaternary Ammonium Salt-Coated Nickel-Titanium Memory Alloy Anchors

BACKGROUND

For patients with osteoporosis and rotator cuff tears, there is still no consensus on current treatment methods. The material, structure, and number of anchors have important effects on the repair outcome.

PURPOSE

To investigate the use of chitosan quaternary ammonium salt-coated nickel-titanium memory alloy (NTMA) anchors to treat rotator cuff injury in shoulders with osteoporosis in a rabbit osteoporosis model.

STUDY DESIGN

Controlled laboratory study.

METHODS

A novel winged NTMA anchor was designed to test in normal and osteoporotic bone models in vitro. These models were assessed for maximum failure load and bone damage in various traction directions. A chitosan-sodium alginate composite was coated onto NTMA anchor surfaces using glutaraldehyde cross-linking and electrostatic layering techniques. An osteoporotic rabbit model was created using ovariectomy combined with glucocorticoid treatment. A rabbit model with acute injury to the supraspinatus muscle was established and repaired using titanium alloy anchors, NTMA anchors, and coated NTMA (CNTMA) anchors. To evaluate the efficacy of the anchors, biomechanical testing and staining with hematoxylin and eosin were performed 6 and 12 weeks after surgery. A micro-computed tomography scan was performed 12 weeks after surgery.

RESULTS

In the osteoporotic bone model, NTMA anchors exhibited greater failure loads than titanium anchors under 45° and 90° traction forces (P < .05). The surface-modified material showed a lower contact angle compared with unmodified material. Cell Counting Kit-8 (CCK-8) assays showed that the composite coating promoted osteoblast proliferation. The CNTMA anchor group exhibited the greatest maximum failure load at each time point. Hematoxylin and eosin staining revealed greater trabecular thickness in the CNTMA anchor group than in the other groups at 6 and 12 weeks after surgery. At 12 weeks after surgery, micro-computed tomography revealed an increased number and thickness of bone trabeculae in the NTMA anchor group, along with a widened trabecular gap (P < .05). After the NTMA anchor biplane unfolded, the gap between the biplane and anchor showed bone tissue growth.

CONCLUSION

Chitosan quaternary ammonium salt-coated NTMA anchors enhanced fixation strength and promoted local osteogenesis during osteoporotic rotator cuff repair, suggesting that the use of these anchors facilitates the repair of osteoporotic rotator cuff injuries in osteoporotic bones.

CLINICAL RELEVANCE

Innovations in anchor nailing may be effective in reducing rates of repair failure for rotator cuff tears combined with osteoporosis.

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.

Cement augmentation of suture anchors in the proximal humerus during rotator cuff repair improves pullout strength: a systematic review

IMPORTANCE

Rotator cuff pathology is a growing concern in the ageing population. If cement augmentation of suture anchors improves pullout strength, its application can potentially be applied in cases of poor bone quality to prevent anchor failure.

OBJECTIVE

To evaluate the biomechanical benefits and fixation strength of cement-augmented versus non-augmented suture anchors in the proximal humerus during rotator cuff repair (RCR).

EVIDENCE REVIEW

A systematic review of PubMed, Embase and Cochrane Library was performed to identify all published articles reporting on biomechanical analysis of suture anchors in the shoulder in a cadaveric model. Inclusion criteria required fresh-frozen specimens, placement in the footprint of the proximal humerus, and comparative assessment of fixation constructs with or without polymethylmethacrylate (PMMA) or bioabsorbable composite cement augmentation. Biomechanical testing procedure, cement augmentation method and pullout force were assessed.

FINDINGS

After review of 105 abstracts, seven full manuscripts met inclusion criteria. Six of seven studies reported statistically significant differences in mean pullout force between augmented (three PMMAs, three composites, one PMMA vs composite) and non-augmented anchors. Of two studies evaluating cycles to failure, both found a significant increase in the augmented versus non-augmented anchors. Of two studies stratifying by anchor position, both investigations identified significant differences in mean pullout strength between augmented and non-augmented anchors at the posteromedial and anterolateral anchor positions.

CONCLUSIONS AND RELEVANCE

Cement augmentation of suture anchors in cadaveric humeri for RCR improves pullout strength regardless of cement type used or anchor position. Cement augmentation may provide a viable option for future clinical application.

LEVEL OF EVIDENCE

IV, systematic review.

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.

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.

Predictors of outcomes after arthroscopic transosseous equivalent rotator cuff repair in 155 cases: a propensity score weighted analysis of knotted and knotless self-reinforcing repair techniques at a minimum of 2 years

PURPOSE

To evaluate the outcomes of two commonly used transosseous-equivalent (TOE) arthroscopic rotator cuff repair (RCR) techniques for full-thickness supraspinatus tendon tears (FTST) using a robust multi-predictor model.

METHODS

155 shoulders in 151 patients (109 men, 42 women; mean age 59 ± 10 years) who underwent arthroscopic RCR of FTST, using either a knotted suture bridging (KSB) or a knotless tape bridging (KTB) TOE technique were included. ASES and SF-12 PCS scores assessed at a minimum of 2 years postoperatively were modeled using propensity score weighting in a multiple linear regression model. Patients able to return to the study center underwent a follow-up MRI for evaluation of rotator cuff integrity.

RESULTS

The outcome data were available for 137 shoulders (88%; n = 35/41 KSB; n = 102/114 KTB). Seven patients (5.1%) that underwent revision rotator cuff surgery were considered failures. The median postoperative ASES score of the remaining 130 shoulders was 98 at a mean follow-up of 2.9 years (range 2.0-5.4 years). A higher preoperative baseline outcome score and a longer follow-up had a positive effect, whereas a previous RCR and workers' compensation claims (WCC) had a negative effect on final ASES or SF 12 PCS scores. The repair technique, age, gender and the number of anchors used for the RCR had no significant influence. Fifty-two patients returned for a follow-up MRI at a mean of 4.4 years postoperatively. Patients with a KSB RCR were significantly more likely to have an MRI-diagnosed full-thickness rotator cuff re-tear (p < 0.05).

CONCLUSIONS

Excellent outcomes can be achieved at a minimum of 2 years following arthroscopic KSB or KTB TOE RCR of FTST. The preoperative baseline outcome score, a prior RCR, WCC and the length of follow-up significantly influenced the outcome scores. The repair technique did not affect the final functional outcomes, but patients with KTB TOE RCR were less likely to have a full-thickness rotator cuff re-tear.

LEVEL OF EVIDENCE

Level III, Retrospective Comparative Study.

In vitro Growth Pattern of Primary Human Osteoblasts on Calcium Phosphate- and Polymethylmethacrylate-Based Bone Cement

BACKGROUND/PURPOSE

Polymethylmethacrylate (PMMA) and calcium phosphate (Ca-P) cements are widely used for arthroplasty surgery and augmentation of bone defects. However, aseptic implant loosening in absence of wear-induced osteolysis indicates an unfavourable interaction between the cement surface and human osteoblasts. Our underlying hypothesis is that cement surfaces directly modify cell viability, proliferation rate, and cell differentiation.

METHODS

To test this hypothesis, we examined primary human osteoblasts harvested from six individuals. These cells were pooled and subsequently seeded directly on cement pellets prepared from Palacos® R, Palacos® R+G, and Norian® Drillable cements. After incubation for 24 and 72 h, cell viability, proliferation rate, apoptosis rate, and cell differentiation were analysed.

RESULTS

Upon cultivation of human osteoblasts on cement surfaces, we observed a significantly reduced cell viability and DNA content compared to the control. Analysis of the apoptosis rate revealed an increase for cells on Palacos R and Norian Drillable, but a significant decrease on Palacos R+G compared to the control. Regarding osteogenic differentiation, significantly lower values of alkaline phosphatase enzyme activity were identified for all cement surfaces after 24 and 72 h compared to cultivation on tissue culture plastic, serving as control.

CONCLUSIONS

In summary, these data suggest a limited biocompatibility of both PMMA and Ca-P cements, necessitating further research to reduce unfavourable cell-cement interactions and consequently extend implant survival.