Enhancement of rotator cuff tendon-bone healing using bone marrow-stimulating technique along with hyaluronic acid

Hyaluronic acid/PEO electrospun tube reduces tendon adhesion to levels comparable to native tendons - An in vitro and in vivo study

A major problem after tendon injury is adhesion formation to the surrounding tissue leading to a limited range of motion. A viable strategy to reduce adhesion extent is the use of physical barriers that limit the contact between the tendon and the adjacent tissue. The purpose of this study was to fabricate an electrospun bilayered tube of hyaluronic acid/polyethylene oxide (HA/PEO) and biodegradable DegraPol® (DP) to improve the anti-adhesive effect of the implant in a rabbit Achilles tendon full laceration model compared to a pure DP tube. Additionally, the attachment of rabbit tenocytes on pure DP and HA/PEO containing scaffolds was tested and Scanning Electron Microscopy, Fourier-transform Infrared Spectroscopy, Differential Scanning Calorimetry, Water Contact Angle measurements, and testing of mechanical properties were used to characterize the scaffolds. In vivo assessment after three weeks showed that the implant containing a second HA/PEO layer significantly reduced adhesion extent reaching levels comparable to native tendons, compared with a pure DP implant that reduced adhesion formation only by 20 %. Tenocytes were able to attach to and migrate into every scaffold, but cell number was reduced over two weeks. Implants containing HA/PEO showed better mechanical properties than pure DP tubes and with the ability to entirely reduce adhesion extent makes this implant a promising candidate for clinical application in tendon repair.

Platelet-rich plasma-derived exosomes promote rotator cuff tendon-bone healing

BACKGROUND

Rotator cuff tear (RCT) is the most common type of shoulder joint injury, platelet-rich plasma-derived exosomes (PRP-exos) are highly promising in tissue repair and regeneration. The purpose of this study was to determine the function of PRP-exos in rotator cuff tendon-bone healing.

METHODS

PRP-exos were isolated from the rabbit whole blood by differential ultracentrifugation and characterized through transmission electron microscopy assay, nanoparticle tracking analysis, and western blotting. Alkaline phosphatase and Von Kossa staining were used to show tendon-derived stem cell (TDSC) differentiation. RT-qPCR and western blotting were performed to detect COL II, SOX-9, and TIMP-1. To determine the therapeutic effects of PRP-exos in vivo. Thirty New Zealand white rabbits were divided into control, model, and PRP-exos groups. The RCT animal model was constructed. The changes in tendon-bone tissue were determined by HE staining. Contents of COL-II, SOX-9, and TIMP-1 were determined by immunohistochemistry staining.

RESULTS

PRP-exos were successfully isolated from rabbit blood. PRP-exos promoted TDSC proliferation and differentiation and also induced tendon-specific markers COL II, SOX-9, and TIMP-1 production. In vivo study revealed that PRP-exos promoted early healing of injured tendons. Rabbits treated with PRP-exos had better tissue arrangement in the tear site. Additionally, the contents of COL II, SOX-9, and TIMP-1 were also increased in the RCT rabbit model after PRP-exos treatment.

CONCLUSIONS

PRP-exos enhanced tendon-bone healing by promoting TDSC proliferation and differentiation. This finding indicates that PRP-exos can serve as a promising strategy to treat rotator cuff tendon-bone healing.

Local Intraoperative Marrow-Derived Augmentation for Primary Rotator Cuff Repair: An Updated Systematic Review and Meta-analysis of Studies From 2010 to 2022

Background

Recurrent tears of the rotator cuff pose a substantial problem despite advances in repair technique. Biologic augmentation via marrow stimulation or vented anchors may strengthen the suture-tendon junction and improve healing rates of native tissue, thereby enhancing outcomes of primary surgical repair.

Purpose

To provide a focused systematic review and meta-analysis of local, intraoperative marrow-derived augmentation techniques in clinical primary rotator cuff repair.

Study Design

Systematic review; Level of evidence, 4.

Methods

A systematic review of PubMed, Embase, and Cochrane was conducted following PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. A total of 2131 studies from 2010 to 2022, focused on either marrow stimulation or vented anchors, were isolated and classified as either preclinical or clinical. Meta-analysis was performed for comparative marrow stimulation and vented anchor studies. Heterogeneity was tested through calculation of I ².

Results

A total of 13 clinical studies were included in the review. All 9 comparative studies included in the meta-analysis demonstrated high methodologic quality or a low risk of bias. The pooled retear rate across all 9 clinical studies for patients undergoing marrow stimulation was 11%. For the 5 studies in the meta-analysis, the pooled retear rates were 15% for marrow stimulation and 30% for controls. Meta-analysis demonstrated a significant difference in the overall retear rate that favored marrow stimulation (odds ratio [OR], 0.41; 95% CI, 0.25-0.66; P = .0003; I ² = 0%). Similarly, meta-analysis of the Constant score at final follow-up demonstrated a statistically significant difference between the 2 groups that favored a higher Constant score in the marrow stimulation group (mean difference, 2.84; 95% CI, 1.02-4.66; P = .002; I ² = 29%). Vented anchors demonstrated improved ossification and bone density at the anchor site, but no difference in outcomes or retear. Pooled retear rates were 22.5% for vented anchors and 27.8% for controls.

Conclusion

Current evidence demonstrates that marrow-stimulation techniques may have a positive impact on healing and retear rate, while vented anchors have a muted impact relative to nonvented anchors. Although available evidence is limited and more research is needed, findings to date suggest that marrow stimulation techniques may be an inexpensive, straightforward technique to consider in qualifying patients to prevent rotator cuff retears.

Polysaccharide-Based Composite Scaffolds for Osteochondral and Enthesis Regeneration

The rotator cuff and Achilles tendons along with the anterior cruciate ligament (ACL) are frequently injured with limited healing capacity. At the soft-hard tissue interface, enthesis is prone to get damaged and its regeneration in osteochondral defects is essential for complete healing. The current clinical techniques used in suturing procedures to reattach tendons to bones need much improvement for the generation of the native interface tissue, that is, enthesis, for patients to regain their full functions. Recently, inspired by the composite native tissue, much effort has been made to fabricate composite scaffolds for enthesis tissue regeneration. This review first focuses on the studies that used composite scaffolds for the regeneration of enthesis. Then, the use of polysaccharides for osteochondral tissue engineering is reviewed and their potential for enthesis regeneration is presented based on their supporting effects on osteogenesis and chondrogenesis. Gellan gum (GG) is selected and reviewed as a promising polysaccharide due to its unique osteogenic and chondrogenic activities that help avoid the inherent weakness of dissimilar materials in composite scaffolds. In addition, original preliminary results showed that GG supports collagen type I production and upregulation of osteogenic marker genes. Impact Statement Enthesis regeneration is essential for complete and functional healing of tendon and ligament tissues. Current suturing techniques to reattach the tendon/ligament to bones have high failure rates. This review highlights the studies on biomimetic scaffolds aimed to regenerate enthesis. In addition, the potential of using polysaccharides to regenerate enthesis is discussed based on their ability to regenerate osteochondral tissues. Gellan gum is presented as a promising biopolymer that can be modified to simultaneously support bone and cartilage regeneration by providing structural continuity for the scaffold.

Clinical perspectives for repairing rotator cuff injuries with multi-tissue regenerative approaches

Background

In the musculoskeletal system, bone, tendon, and muscle form highly integrated multi-tissue units such as the rotator cuff complex, which facilitates functional and dynamic movement of the shoulder joint. Understanding the intricate interplay among these tissues within clinical, biological, and engineering contexts is vital for addressing challenging issues in treatment of musculoskeletal disorders and injuries.

Methods

A wide-ranging literature search was performed, and findings related to the socioeconomic impact of rotator cuff tears, the structure-function relationship of rotator cuff bone-tendon-muscle units, pathophysiology of injury, current clinical treatments, recent state-of-the-art advances (stem cells, growth factors, and exosomes) as well as their regulatory approval, and future strategies aimed at engineering bone-tendon-muscle musculoskeletal units are outlined.

Results

Rotator cuff injuries are a significant socioeconomic burden on numerous healthcare systems that may be addressed by treating the rotator cuff as a single complex, given its highly integrated structure-function relationship as well as degenerative pathophysiology and limited healing in bone-tendon-muscle musculoskeletal tissues. Current clinical practices for treating rotator cuff injuries, including the use of commercially available devices and evolving trends in surgical management have benefited patients while advances in application of stem/progenitor cells, growth factors, and exosomes hold clinical potential. However, such efforts do not emphasize targeted regeneration of bone-tendon-muscle units. Strategies aimed at regenerating bone-tendon-muscle units are thus expected to address challenging issues in rotator cuff repair.

Conclusions

The rotator cuff is a highly integrated complex of bone-tendon-muscle units that when injured, has severe consequences for patients and healthcare systems. State-of-the-art clinical treatment as well as recent advances have resulted in improved patient outcome and may be further enhanced by engineering bone-tendon-muscle multi-tissue grafts as a potential strategy for rotator cuff injuries.

Translational Potential of this Article

This review aims to bridge clinical, tissue engineering, and biological aspects of rotator cuff repair and propose a novel therapeutic strategy by targeted regeneration of multi-tissue units. The presentation of these wide-ranging and multi-disciplinary concepts are broadly applicable to regenerative medicine applications for musculoskeletal and non-musculoskeletal tissues.

Subacromial Injections of Low- or High-Molecular-Weight Hyaluronate Versus Physical Therapy for Shoulder Tendinopathy: A Randomized Triple-Blind Controlled Trial

OBJECTIVE

Shoulder tendinopathy is a prevalent and debilitating problem. We compared the effects of subacromial high- or low-molecular-weight hyaluronate injection with physical therapy (PT) in shoulder tendinopathy.

DESIGN

A triple-blinded randomized controlled trial.

SETTING

We conducted the trial in an outpatient clinic at a teaching hospital.

PARTICIPANTS

In total, 79 patients with shoulder tendinopathy were randomly allocated to high- (n = 27) or low-molecular-weight (n = 28) hyaluronate or PT (n = 24) groups.

INTERVENTIONS

We administered a 20-mg injection of high- or low-molecular-weight hyaluronate. For PT, we prescribed 10 sessions of physiotherapy and exercise.

OUTCOME MEASURES

The primary outcome was shoulder pain and the secondary outcomes included Disability of the Arm Shoulder and Hand score, shoulder range of movement and QoL. We measured the outcomes at baseline, 1, and 3 months of treatment, and assessed shoulder pain at the sixth month postintervention.

RESULTS

The interventions were all clinically beneficial in the management of tendinopathy for high- (n = 25) and low-molecular-weight (n = 24) hyaluronate and PT (n = 19) groups (all P < 0.05). However, between-group analyses indicated that hyaluronate preparations were more effective in controlling pain, decreasing disability, increasing range of motion, and improving the quality of life (all P < 0.05). The pain and subjective feeling of rigidity at the injection area ( P = 0.012) were less prominent for low-molecular-weight hyaluronate.

CONCLUSION

High- or low-molecular-weight hyaluronate is more effective than PT in the treatment of shoulder tendinopathy. The clinical benefits of hyaluronate last for at least 3 months, and the pain alleviation sustains partially for 6 months. Shoulder injection of low-molecular-weight hyaluronate is more tolerable to the patient than high-molecular-weight hyaluronate.

Hydrogel Development for Rotator Cuff Repair

Rotator cuff tears (RCTs) are common in shoulder disease and disability. Despite significant advances in surgical repair techniques, 20–70% of patients still have postoperative rotator cuff dysfunction. These functional defects may be related to retear or rotator cuff quality deterioration due to tendon retraction and scar tissue at the repair site. As an effective delivery system, hydrogel scaffolds may improve the healing of RCTs and be a useful treatment for irreparable rotator cuff injuries. Although many studies have tested this hypothesis, most are limited to laboratory animal experiments. This review summarizes differences in hydrogel scaffold construction, active ingredients, and application methods in recent research. Efforts to determine the indications of hydrogel scaffolds (with different constructions and cargos) for various types of RCTs, as well as the effectiveness and reliability of application methods and devices, are also discussed.

Roles of Oxidative Stress in Acute Tendon Injury and Degenerative Tendinopathy-A Target for Intervention

Both acute and chronic tendon injuries are disabling sports medicine problems with no effective treatment at present. Sustained oxidative stress has been suggested as the major factor contributing to fibrosis and adhesion after acute tendon injury as well as pathological changes of degenerative tendinopathy. Numerous in vitro and in vivo studies have shown that the inhibition of oxidative stress can promote the tenogenic differentiation of tendon stem/progenitor cells, reduce tissue fibrosis and augment tendon repair. This review aims to systematically review the literature and summarize the clinical and pre-clinical evidence about the potential relationship of oxidative stress and tendon disorders. The literature in PubMed was searched using appropriate keywords. A total of 81 original pre-clinical and clinical articles directly related to the effects of oxidative stress and the activators or inhibitors of oxidative stress on the tendon were reviewed and included in this review article. The potential sources and mechanisms of oxidative stress in these debilitating tendon disorders is summarized. The anti-oxidative therapies that have been examined in the clinical and pre-clinical settings to reduce tendon fibrosis and adhesion or promote healing in tendinopathy are reviewed. The future research direction is also discussed.

In situ gel implant for postsurgical wound management and extended chemoimmunotherapy against breast cancer recurrence

Postsurgical recurrence of breast cancer is closely related to the inflammatory tumor microenvironment evoked by surgical wounds. Toll-like receptor 4 (TLR4) signaling contributes to NF-κB activation thus secreting various inflammatory cytokines. Herein, we developed an in situ photo-crosslinked hydrogel (D/T gel) concurrently loaded with doxorubicin (DOX) and a TLR4 antagonist, resatorvid (TAK-242). Its therapeutic effect against breast cancer postsurgical relapse was accomplished through remodeling the proinflammatory tumor microenvironment. The obtained gel network exhibited ideal biodegradability and biocompatibility, which motivated dermal wound healing in the full thickness wound model in mice. Despite the initial burst release of DOX, D/T gels exhibited extended-release of both DOX and TAK-242 for up to 21 days in vitro. TAK-242 was demonstrated to inhibit the lipopolysaccharide-induced NF-κB activation and downregulate TLR4 levels in both RAW264.7 and 4T1 cells. In a 4T1-Luc tumor postsurgical recurrence model, D/T gel significantly suppressed recurrent tumor growth by elevating the concentrations of DOX and TAK-242 at the tumor sites and remodeling the TLR4 activation-induced proinflammatory microenvironment. Overall, the D/T gel platform technology is proven to deliver therapeutics directly to the surgical wound bed, attenuating the dual inflammatory responses induced by DOX and surgical wounding thus greatly potentiating its efficacy in preventing postsurgical tumor recurrence. STATEMENT OF SIGNIFICANCE: Postsurgical recurrence of breast cancer is closely related to the inflammatory tumor microenvironment (TME) evoked by surgical wounds. Although chemotherapeutics lead to extensive residual tumor cell necrosis, multiple inflammatory cytokines are secreted simultaneously, which are conducive to tumor recurrence. In this work, a TLR4 antagonist, TAK-242, was combined with DOX to reverse the dual inflammatory TME induced by surgical wounding and chemotherapy. To elevate the concentration of therapeutics at the tumor site, a photocrosslinked hydrogel (D/T gel) implant coloaded with TAK-242 and DOX was developed and applied on the postsurgical bed. Consequently, D/T gel attenuated the dual inflammatory responses and greatly potentiated its efficacy in preventing postsurgical tumor recurrence.

Electrospun tube reduces adhesion in rabbit Achilles tendon 12 weeks post-surgery without PAR-2 overexpression

One great challenge in surgical tendon repair is the minimization of peritendinous adhesions. An electrospun tube can serve as a physical barrier around a conventionally sutured tendon. Six New Zealand White rabbits had one Achilles tendon fully transsected and sutured by a 4-strand suture. Another six rabbits had the same treatment, but with the additional electrospun DegraPol tube set around the sutured tendon. The adhesion formation to the surrounding tissue was investigated 12 weeks post-operation. Moreover, inflammation-related protease-activated receptor-2 (PAR-2) protein expression was assessed. Finally, rabbit Achilles tenocyte cultures were exposed to platelet-derived growth factor-BB (PDGF-BB), which mimicks the tendon healing environment, where PAR-2 gene expression was assessed as well as immunofluorescent staining intensity for F-actin and α-tubulin, respectively. At 12 weeks post-operation, the partially degraded DegraPol tube exhibited significantly lower adhesion formation (- 20%). PAR-2 protein expression was similar for time points 3 and 6 weeks, but increased at 12 weeks post-operation. In vitro cell culture experiments showed a significantly higher PAR-2 gene expression on day 3 after exposure to PDGF-BB, but not on day 7. The cytoskeleton of the tenocytes changed upon PDGF-BB stimulation, with signs of reorganization, and significantly decreased F-actin intensity. An electrospun DegraPol tube significantly reduces adhesion up to twelve weeks post-operation. At this time point, the tube is partially degraded, and a slight PAR-2 increase was detected in the DP treated tendons, which might however arise from particles of degrading DegraPol that were stained dark brown. PAR-2 gene expression in rabbit tenocytes reveals sensitivity at around day 10 after injury.

Low Molecular-weight Hyaluronic Acid Versus Physiotherapy for the Treatment of Supraspinatus Tendinopathy: A Randomized Comparative Clinical Trial

INTRODUCTION

The tendons of the rotator cuff are major sources of shoulder pain. This study aimed to compare the effects of low molecular-weight hyaluronic acid with physiotherapy (PT) in patients with supraspinatus tendinopathy (ST).

METHODS

We carried out a parallel two-group randomized comparative clinical trial in an outpatient clinic of physical medicine and rehabilitation at a teaching hospital. In total, 51 patients (31 women) aged 20 to 55 years with ST were randomly allocated to subacromial hyaluronate injection (n = 28) and PT (n = 23) groups. For the hyaluronate group, we administered a single injection of 2 mL (20 mg) hyaluronate 1% (500 to 700 kDa). For PT, we prescribed three sessions of treatment per week for 12 weeks, totaling 36 sessions including rotator cuff activation exercises. The primary outcome was shoulder pain in the visual analog scale. The secondary outcomes included the range of movement and the disability score of the shoulder, and a World Health Organization questionnaire on quality of life. We did the measurements at the baseline and at one, four, and 12 weeks after intervention.

RESULTS

The results showed that both interventions were beneficial in the management of ST. However, hyaluronate was more effective in reducing shoulder pain at rest and during activities (both P < 0.001, effect size = 0.52 and 0.68, respectively). The two interventions similarly decreased patients' disability (P = 0.196). Hyaluronate improved shoulder motion and the quality of life better than PT.

CONCLUSION

In the treatment of ST, low molecular-weight hyaluronate is more effective than PT, at least for three months. Particularly, hyaluronate is more successful in alleviating pain.

Effect of co-administration of atelocollagen and hyaluronic acid on rotator cuff healing

Background

This study aimed to evaluate the co-administration effect of atelocollagen combined with hyaluronic acid (HA) injections for treatment of full-thickness rotator cuff tear (RCT).

Methods

Eighty patients who underwent arthroscopic rotator cuff repair for full-thickness RCT from March 2018 to November 2019 were enrolled. The patients were randomly allocated to the following groups: combined atelocollagen and HA injection (group I, n=28), only HA injection (group II, n=26), and no injection (group III, n=26). Clinical outcomes were assessed at 3, 6, and 12 months after surgery using the American Shoulder and Elbow Surgeons score, visual analog scale pain score , functional scores (pain visual analog scale, function visual analog score), and range of motion. Magnetic resonance imaging was performed 12 months after surgery to evaluate rotator cuff integrity.

Results

Preoperative demographic data and postoperative clinical outcomes did not differ significantly among the three groups (p>0.05). However, in group I, the number of steroid injections after surgery was significantly lower than that in the other groups (p=0.011). The retear rate on follow-up magnetic resonance imaging was significantly higher in group II (9.5%, n=2) and group III (13.6%, n=3) than in group I (0%) (p=0.021).

Conclusions

Co-administration of atelocollagen and HA improves healing of the rotator cuff and increases the integrity of the rotator cuff repair site. This study provides encouraging evidence for use of combined atelocollagen-HA injections to treat patients with full-thickness RCT.

The interaction between human rotator cuff tendon and subacromial bursal tissue in co-culture

BACKGROUND

The role of subacromial bursa in rotator cuff pathology is unclear. Along with recognized inflammatory potential, current data demonstrate the presence of mesenchymal stem cells and potential regenerative properties of the bursa. The purpose of this study was to (1) approximate an in vitro co-culture model that represents interaction between torn rotator cuff tendon and subacromial bursa, (2) quantify the cellular activity of tendon and bursa and their interactions, (3) use this model to induce a state of inflammation present with rotator cuff pathology.

METHODS

In part 1, tendon and bursa samples were obtained from 6 patients undergoing rotator cuff repair. Tendon and bursa were cultured alone and together in co-culture wells for 21 days. Markers specific for tenocyte gene expression (tenascin C, decorin, etc) were measured in both tendon and bursa alone and compared to co-culture models. In part 2 of the study, an inflammatory state was induced with interleukin-1β treatment, and markers of inflammation were measured via protein assay at 0 and 21 days in samples from 7 additional patients.

RESULTS

There was an increase in tendon and bursa markers in nearly all groups as evidenced by increased gene expression of known tendon and bursa markers. There was a significant increase in gene expression when torn tendon was co-cultured with bursa compared with culturing alone. Additionally, a state of inflammation was induced as evidenced by increased markers of inflammation, inflammatory protein concentration, and inflammatory cells and disruption of histologic morphology.

CONCLUSION

There is a clear interaction between rotator cuff tendon and the milieu produced by the subacromial bursa in this in vitro co-culture system that is significantly different when compared to an isolated culture of tendon and bursa. This system was successfully used to induce a state of inflammation that may represent in vivo inflammation. This in vitro model of rotator cuff pathology can aid investigators in testing effects of agents proposed to improve rotator cuff healing. This can lead to further knowledge regarding effective treatment options.

A Systematic Review of Tissue Engineering Scaffold in Tendon Bone Healing in vivo

Background: Tendon-bone healing is an important factor in determining the success of ligament reconstruction. With the development of biomaterials science, the tissue engineering scaffold plays an extremely important role in tendon-bone healing and bone tissue engineering. Materials and Methods: Electronic databases (PubMed, Embase, and the Web of Science) were systematically searched for relevant and qualitative studies published from 1 January 1990 to 31 December 2019. Only original articles that met eligibility criteria and evaluated the use of issue engineering scaffold especially biomaterials in tendon bone healing in vivo were selected for analysis. Results: The search strategy identified 506 articles, and 27 studies were included for full review including two human trials and 25 animal studies. Fifteen studies only used biomaterials like PLGA, collage, PCL, PLA, and PET as scaffolds to repair the tendon-bone defect, on this basis, the rest of the 11 studies using biological interventions like cells or cell factors to enhance the healing. The adverse events hardly ever occurred, and the tendon bone healing with tissue engineering scaffold was effective and superior, which could be enhanced by biological interventions. Conclusion: Although a number of tissue engineering scaffolds have been developed and applied in tendon bone healing, the researches are mainly focused on animal models which are with limitations in clinical application. Since the efficacy and safety of tissue engineering scaffold has been proved, and can be enhanced by biological interventions, substantial clinical trials remain to be done, continued progress in overcoming current tissue engineering challenges should allow for successful clinical practice.

High- Versus Low-Molecular-Weight Hyaluronic Acid for the Treatment of Rotator Cuff Tendinopathy: A Triple-Blind Randomized Comparative Trial

BACKGROUND

Shoulder pain most commonly originates from the tendon structures of the rotator cuff.

OBJECTIVE

We compared the clinical effects of high- versus low-molecular-weight (LMW) hyaluronic acid for the management of rotator cuff tendinopathy.

METHODS

We carried out a parallel, triple-blind, randomized comparative trial at a teaching hospital. In total, 56 patients aged 16 to 70 years with rotator cuff tendinopathy were randomly allocated to 2 groups. We administered a single shoulder injection of either 1 mL of 1% high- (>2000 kDa) or 1 mL of 1% LMW hyaluronate (500-700 kDa) to the corresponding groups. The primary outcome was the intensity of shoulder pain. The secondary outcomes were range of motion and disability of the shoulder, and quality of life. We performed the measurements at baseline and at 1, 4, and 12 weeks postintervention. The pain measurements were repeated at the sixth month postintervention.

RESULTS

Comparisons of baseline versus 3 months showed that both interventions were beneficial in the management of the tendinopathy (all P values <0.05). However, between-group analyses did not indicate any clinically significant difference between the 2 medications. The pain, induration (P = 0.007), and inflammation at the site of the injection were less prominent for LMW hyaluronate.

CONCLUSION AND RELEVANCE

Both medications are effective for the treatment of tendinopathy. The benefits last at least for 3 months, and pain alleviation lasts partially for 6 months. The shoulder injection of LMW hyaluronate is more tolerable to the patient. Therefore, we recommend LMW hyaluronate as the first choice for the management of rotator cuff tendinopathy.

Long-term study on the osteogenetic capability and mechanical behavior of a new resorbable biocomposite anchor in a canine model

Background

Biodegradable suture anchors are commonly used for repairing torn rotator cuffs, but these biodegradable materials still suffer from low mechanical strength, poor osteointegration, and the generation of acidic degradation byproducts.

Method

The purpose of this study was to evaluate the long-term mechanical behavior and osteogenetic capabilities of a biocomposite anchor injection molded with 30% β-tricalcium phosphate microparticles blended with 70% poly (L-lactide-co-glycolide) (85/15). This study investigated in vitro degradation and in vivo bone formation in a canine model. The initial mechanical behavior, mechanical strength retention with degradation time, and degradation features were investigated.

Results

The results showed that the biocomposite anchor had sufficient initial mechanical stability confirmed by comparing the initial shear load on the anchor with the minimum shear load borne by an ankle fracture fixation screw, which is considered a worst-case implantation site for mechanical loading. The maximum shear load retention of the biocomposite anchor was 83% at 12 weeks, which is desirable, as it aligns with the rate of bone healing. The β-tricalcium phosphate fillers were evenly dispersed in the polymeric matrix and acted to slow the degradation rate and improve the mechanical strength of the anchor. The interface characteristics between the β-tricalcium phosphate particles and the polymeric matrix changed the degradation behavior of the biocomposite. Phosphate buffer saline was shown to diffuse through the interface into the biocomposite to inhibit the core accelerated degradation rate. In vivo, the addition of β-tricalcium phosphate induced new bone formation. The biocomposite material developed in this study demonstrated improved osteogenesis in comparison to a plain poly (L-lactide-co-glycolide) material. Neither anchor produced adverse tissue reactions, indicating that the biocomposite had favorable biocompatibility following long-term implantation.

Conclusion

In summary, the new biocomposite anchor presented in this study had favorable osteogenetic capability, mechanical property, and controlled degradation rate for bone fixation.

Translational potential of this article

The new biocomposite anchor had sufficient initial and long-term fixation stability and bone formation capability in the canine model. It is indicated that the new biocomposite anchor has a ​potential for orthopedic application.