Effects of lidocaine on torn rotator cuff tendons

Cytotoxicity of local anaesthetics and protective effects of platelet rich plasma on equine tenocytes: An in vitro study

Local anaesthetics (LAs) can have detrimental effects on rat, bovine, canine, and human tendon tissues and cells. Currently, there has been no available data on the impact of these drugs on equine tenocytes. Even if LA injection for managing painful tendon conditions in horses is limited, it is usually used via intra-articular, intrasynovial, perineural, and intrathecal as well as for lameness examinations. In this in vitro study, the cytotoxic effects of LAs, including lidocaine, mepivacaine, and bupivacaine on equine tenocytes, in the presence and absence of platelet rich plasma (PRP), were investigated. PRP accelerates tissue healing and can exert cytoprotective effects on different cell types exposed to different stressful conditions, including drugs. Results indicated that the exposure to LAs significantly reduced tenocytes viability in dose- and time-dependent manners while PRP was able to counteract their cytotoxic effects. Furthermore, microscopy and flow cytometry analyses revealed apoptosis and necrosis in equine tenocytes exposed to these drugs, that were both reduced when PRP was in the medium. These findings highlight the importance of considering the tenocyte toxicity associated with intrathecal and intraneural LA injections, as they might affect tenocytes or reduce the efficacy of associated therapies. Moreover, this study also highlights the protective effects of PRP, which could make LA injections safer.

Lidocaine inhibits migration of tenocytes by downregulating focal adhesion kinase and paxillin phosphorylation

Lidocaine is the most frequently applied local infiltration anesthetic agent for treating tendinopathies. However, studies have discovered lidocaine to negatively affect tendon healing. In the current study, the molecular mechanisms and effects of lidocaine on tenocyte migration were evaluated. We treated tenocytes intrinsic to the Achilles tendons of Sprague-Dawley rats with lidocaine. The migration ability of cells was analyzed using electric cell-substrate impedance sensing (ECIS) and scratch wound assay. We then used a microscope to evaluate the cell spread. We assessed filamentous actin (F-actin) cytoskeleton formation through immunofluorescence staining. In addition, we used Western blot analysis to analyze the expression of phospho-focal adhesion kinase (FAK), FAK, phospho-paxillin, paxillin, and F-actin. We discovered that lidocaine had an inhibitory effect on the migration of tenocytes in the scratch wound assay and on the ECIS chip. Lidocaine treatment suppressed cell spreading and changed the cell morphology and F-actin distribution. Lidocaine reduced F-actin formation in the tenocyte during cell spreading; furthermore, it inhibited phospho-FAK, F-actin, and phospho-paxillin expression in the tenocytes. Our study revealed that lidocaine inhibits the spread and migration of tenocytes. The molecular mechanism potentially underlying this effect is downregulation of F-actin, phospho-FAK, and phospho-paxillin expression when cells are treated with lidocaine.

Additional Effect of Extracorporeal Shockwave Therapy with Lidocaine Injection on Clinical and MRI Findings in Frozen Shoulder: A Prospective, Randomized, Double-Blinded, Placebo-Controlled Trial

INTRODUCTION

Frozen shoulder is a very common musculoskeletal condition and the evidence related to the additional effects of extracorporeal shockwave therapy (ESWT) with intra-articular (IA) lidocaine injection in individuals with frozen shoulder is rare. Therefore, this study aims to compare and investigate the additional effects of extracorporeal shockwave therapy (ESWT) with intra-articular (IA) lidocaine injection in a frozen shoulder.

METHODS

Sixty eligible participants with frozen shoulder were included and the active group (n = 30, age 52.12 ± 5.2 years) received a lidocaine injection (1% lidocaine (Xylocaine) and 2cc (80 mg) methylprednisolone acetate) with active ESWT (3.5 bar air pressure and 2000 pulses with an energy flux density (EFD) ¼ 0.16 mJ/mm2) three sessions a week for 4 weeks. The placebo group (n = 30, age 53.56 ± 5.5 years) received lidocaine injection with placebo treatment (a special head that blocked the shock waves) three sessions a week for 4 weeks. Both groups received progressive resistance exercises (PRE) to the shoulder muscles. The primary outcome was pain intensity, measured with the visual analogue scale. The other outcome measures were the thickness of the coracohumeral ligament (CHL) measured by magnetic resonance imaging (MRI), abduction, and lateral rotation range of motion (ROM), functional disability, kinesiophobia, depression status, and quality of life. Participants were assessed at baseline, after 4 weeks, 8 weeks, and at 6-month follow-up.

RESULTS

The post-intervention at 4 weeks showed an improvement of 2.0 (CI 95% 1.71-2.28) in the active group compared to the placebo group. Similar effects were noted after 8 weeks (2.2) (CI 95% 1.91-2.48) and at the 6-month (1.9) (CI 95% 1.61-2.18) follow-up. Similar improvements were also found in the thickness of the CHL ligament (0.6) (CI 95% 0.46-0.73), abduction and lateral rotation (ROM) (- 23.6) (CI 95% - 27.47 to -19.72), (- 18.10) (CI 95% - 19.72 to - 16.47), functional disability (16.2) (CI 95% 14.85-17.54), kinesiophobia (11.0 (CI 95% 10.21-11.98), depression status (4.4) (CI 95% 4.03-4.76) and quality of life (0.9) (CI 95% 0.79-1.00) (p = 0.001) at the 6-month follow-up period, where mean estimates and their confidence intervals all included worthwhile effects. There were no adverse reactions or side effects noted in either the active or placebo groups during and after the treatment.

CONCLUSIONS

The study concluded that the addition of extracorporeal shockwave therapy after intra-articular lidocaine injection improves pain, functional disability, range of motion, kinesiophobia, depression status, and quality of life in people with frozen shoulder.

TRIAL REGISTRATION

https://ctri.nic.in , identifier; CTRI/2020/04/024834 prospectively registered on 24/04/2020.

Mesoscopic structural analysis via deep learning processing, with a special reference to in vitro alteration in collagen fibre induced by a gap junction inhibitor

Dense connective tissue, including the ligament, tendon, fascia and cornea, is formed by regularly arranged collagen fibres synthesized by fibroblasts (Fbs). The mechanism by which fibre orientation is determined remains unclear. Periodontal ligament Fbs consistently communicate with their surroundings via gap junctions (GJs), leading to the formation of a wide cellular network. A method to culture Fb-synthesized collagen fibres was previously reported by Schafer et al. ('Ascorbic acid deficiency in cultured human fibroblasts'. J. Cell Biol. 34: 83-95, 1967). This method has been applied to investigate the ability and activity of Fb collagen synthesis/phagocytosis using conventional electron microscopy (EM). However, the three-dimensional mesoscopic architecture of collagen fibres and the influence of GJ inhibitors on collagen fibre formation in vitro are poorly understood. In this study, three-dimensional mesoscopic analysis was used to elucidate the mechanism of directional fibre formation. We investigated the influence of GJ inhibitors on collagen formation driven by periodontal ligament Fbs in vitro, histomorphometrically, and the structural properties of in vitro collagen fibre on a mesoscale quantitatively, using correlative light and EM optimized for picrosirius red staining and focused ion beam-scanning EM tomography. Our results indicate that under culture conditions, in the presence of a GJ inhibitor, the orientation of collagen fibres becomes more disordered than that in the control group. This suggests that the GJ might be involved in determining fibre orientation during collagen fibre formation. Elucidation of this mechanism may help develop novel treatment strategies for connective tissue orientation disorders. Graphical Abstract.

Efficacy of high-volume vs very low volume corticosteroid subacromial injection in subacromial impingement syndrome: a randomized controlled trial

Subacromial corticosteroid injections (SCI) treat shoulder pain from subacromial impingement syndrome (SIS). However, a high-volume corticosteroid injection (HVCI) increases the incidence of local and general complications from lidocaine. This study aimed to compare the results of functional and clinical outcomes between the very low-volume corticosteroid injection (VLVCI) and HVCI including to WORC (Western Ontario Rotator Cuff Index), VAS (Visual Analog Scale), DASH (The disabilities of the arm, shoulder, and hand) and ROM (Range of Motion). A total of 64 patients presenting with SIS were evaluated in two SCI volume in a randomization-controlled trial study. The VAS for pain pre-injection and post-injection at 15 min, was from 5.34 ± 2.44 at before injection to 2.44 ± 1.58 at post injection 15 min in the HVCI group (P < 0.001) and from 5.19 ± 2.33 to 2.84 ± 1.49 in VLVCI group (P < 0.001). Not significant differences at mean difference VAS post-injection 15 min VAS (P = 0.324) and Percentage difference VAS pre-injection and post-injection (P = 0.24). All follow-up timing, there were no significant differences in WORC, DASH and ROM between two groups (P > 0.05). The results revealed the VLVCI is non-inferior to HVCI both of functional outcomes and VAS.

Lidocaine Inhibited Tendon Cell Proliferation and Extracellular Matrix Production by Down Regulation of Cyclin A, CDK2, Type I and Type III Collagen Expression

Lidocaine injection is a common treatment for tendon injuries. However, the evidence suggests that lidocaine is toxic to tendon cells. This study investigated the effects of lidocaine on cultured tendon cells, focusing on the molecular mechanisms underlying cell proliferation and extracellular matrix (ECM) production. Tendon cells cultured from rat Achilles tendons were treated with 0.5, 1.0, or 1.5 mg/mL lidocaine for 24 h. Cell proliferation was evaluated by Cell Counting Kit 8 (CCK-8) assay and bromodeoxyuridine (BrdU) assay. Cell apoptosis was assessed by Annexin V and propidium iodide (PI) stain. Cell cycle progression and cell mitosis were assessed through flow cytometry and immunofluorescence staining, respectively. The expression of cyclin E, cyclin A, cyclin-dependent kinase 2 (CDK2), p21, p27, p53, matrix metalloproteinases-2 (MMP-2), matrix metalloproteinases-9 (MMP-9), type I collagen, and type III collagen were examined through Western blotting, and the enzymatic activity of MMP-9 was determined through gelatin zymography. Lidocaine reduced cell proliferation and reduced G1/S transition and cell mitosis. Lidocaine did not have a significant negative effect on cell apoptosis. Lidocaine significantly inhibited cyclin A and CDK2 expression but promoted p21, p27, and p53 expression. Furthermore, the expression of MMP-2 and MMP-9 increased, whereas that of type I and type III collagen decreased. Lidocaine also increased the enzymatic activity of MMP-9. Our findings support the premise that lidocaine inhibits tendon cell proliferation by changing the expression of cell-cycle-related proteins and reduces ECM production by altering levels of MMPs and collagens.

Neurotropin protects rotator cuff tendon cells from lidocaine-induced cell death

Background

Local anesthetics often are used in rotator cuff tears as therapeutic tools, although some cases have reported that they have detrimental effects. Neurotropin (NTP) is used widely in Japan as a treatment for various chronic pain conditions and is shown to have protective effects on cartilage and nerve cells. In this study, we investigated the protective effect of NTP against lidocaine-induced cytotoxicity.

Methods

Tenocytes from rotator cuff tendons were incubated with lidocaine, NTP, lidocaine with NTP, and a control medium. Cell viability was evaluated using the WST-8 assay. Cell apoptosis was detected via annexin V staining using flow cytometry. The expression of BCL-2 and cytochrome c, which are involved in the intrinsic mitochondrial pathway of apoptosis, was evaluated via Western blotting and immunohistochemical staining.

Results

In the cell viability assay, lidocaine decreased cell viability in a dose-dependent manner, and NTP did not affect cell viability. Moreover, NTP significantly inhibited the cytotoxic effect of lidocaine. The flow cytometry analysis showed that lidocaine significantly induced apoptosis in tenocytes, and NTP considerably inhibited this lidocaine-induced apoptosis. Western blotting experiments showed that lidocaine decreased the protein expression of BCL-2, and that NTP conserved the expression of BCL-2, even when used with lidocaine. Immunohistochemical staining for cytochrome c showed that 0.1% lidocaine increased cytochrome c-positive cells, and NTP suppressed lidocaine-induced cytochrome c expression.

Conclusions

NTP suppresses lidocaine-induced apoptosis of tenocytes by inhibiting the mitochondrial apoptotic pathway. Intra-articular/ bursal injection of NTP with lidocaine could protect tenocytes in rotator cuff tendons against lidocaine-induced apoptosis.

Treatment of Rotator Cuff Tears with platelet rich plasma: a prospective study with 2 year follow-up

BACKGROUND

Surgical treatment of full-thickness rotator cuff (RC) tears is associated with generally good results. There is no consensus regarding treatment of partial thickness tears that fail conservative treatment. The purpose of this study was to look at the efficacy and confirm the safety of dual injection PRP into the shoulder of patients with rotator cuff pathology who have failed conservative treatment with followup to two years.

METHODS

Seventy-one shoulders with MRI confirmed, rotator cuff pathology who failed conservative treatment, had dual PRP injection into the rotator cuff. Global improvement, Quick DASH and VAS scores were collected at 6, 12, and 24 months after treatment and comparison of means was used to analyze changes.

RESULTS

No adverse events were seen in any patient. Based on global rating scores positive results were seen in 77.9 % of patients at 6 months, 71.6 % at 1 year, and 68.8 % of patients at 2 years. Mean VAS scores improved from 50.2 [CI 44.4-56.0] pre-injection to 26.2 [CI 19.5-32.9] at 6 months, 22.4[CI 16.1-28.7] at 1 year and 18.2 [CI 12.3-24.1] at 2 years (p < 0.0001 for all). The mean Q- DASH scores (0-100, 100 worse) improved from 39.2 [CI 34.3-44.1] for all patients before treatment to 20.7[CI 15.0-26.4] at 6 months, 18.0[CI 12.9-23.1] at 1 year, and 13.8 [CI 8.4-18.8] at 2 years (p < 0.0001 for all). No patient with partial tear had clinical evidence of progression to full thickness tear. When separated into subgroups based on rotator cuff status, all subgroups showed improvement. Patients in the > 50 % partial tear group had the best overall improvement based on Global Rating scores while those in the tendinitis group had the poorest outcomes.

CONCLUSIONS

PRP injection is a safe and effective treatment for RC cuff injury in patients who have failed conservative treatment of activity modification and physical therapy without deterioration of results two years after treatment. Better results are obtained with greater structural tendon damage than in shoulders with inflammation without structural damage.

TRIAL REGISTRATION

This is not a clinical trial.

Preoperative hyaluronic acid injection modulates postoperative functional outcome in patients undergoing arthroscopic rotator cuff repair

Background

Arthroscopic rotator cuff repair (ARCR) generally yields acceptable clinical results. Hyaluronic acid (HA), a high-molecular-weight polysaccharide, is present in the extracellular matrix of soft connective tissue and synovial fluid, and its injection is known to significantly improve pain and clinical outcomes after rotator cuff injury. Some studies have described the role of HA injections as conservative therapy for rotator cuff tears. Since the subacromial bursa is believed to be the main source of shoulder pain in rotator cuff tears, subacromial injection is frequently used before surgery; however, its relationship with the clinical outcome after surgery remains unclarified. Therefore, we aimed to examine effects of preoperative subacromial HA injection on postoperative clinical outcome in patients with ARCR.

Methods

Ninety-eight patients were divided into a HA injection group and a non-injection group. The functional outcome measured was the University of California, Los Angeles (UCLA) score. Univariate analysis was performed to obtain variables with p values less than 0.1; we then used propensity score analysis, adjusting for pre- and post-operative confounding factors.

Results

The UCLA scores of all patients significantly improved 1 year postoperatively (PO) (p < 0.05). Subacromial HA injections were performed in patients with worse preoperative function. Univariate analysis showed significantly greater improvements in the injection group than in the non-injection group in terms of preoperative UCLA score, trauma, diabetes mellitus, UCLA score 3 months PO, abduction strength 4 months PO, and internal rotation (IR) strength 6 and 12 months PO. Propensity score analysis demonstrated that UCLA scores 3 months PO and IR strength 12 months PO in the injection group were significantly greater than those in the non-injection group. There were no significant differences in postoperative re-tear rates between the groups. In sub-analysis of the injection group, propensity scores showed that concurrent use of local anesthetics did not affect the data, suggesting that HA was effective.

Conclusion

Subacromial injection was administered to patients with worse function before ARCR. Propensity score analysis successfully demonstrated that functional outcome after surgery was improved in patients who were administered this injection compared with patients who were not administered this injection before surgery.

Narrative review: the evidence for neurotoxicity of dental local anesthetics

Dental local anesthesia is performed daily on a global scale. Adverse effects are rare, but the topic of neurotoxicity of local anesthetics deserves to be explored, as publications can be controversial and confusing. Therefore, a need was felt to address and question the evidence for potential neurotoxicity of dental local anesthetics. This review aimed to assess the studies published on the neurotoxicity of dental local anesthetics. A Pubmed® search was conducted between January 2019 and August 2019. This revealed 2802 hits on the topic of neurotoxicity or cytotoxicity of the following anesthetics: lidocaine, prilocaine, mepivacaine, articaine, ropivacaine, and bupivacaine. Only 23 papers were deemed eligible for this review: 17 in vitro studies, 3 reviews and 3 audits of national inquiries. The heterogeneous literature on this topic showed that all dental local anesthetics are potentially neurotoxic in a concentration and/or exposure time fashion. There seems no consensus about what cell lines are to be used to investigate the neurotoxicity of local anesthetics, which makes the comparison between studies difficult and ambiguous. However, the bottom line is that all dental local anesthetics have a neurotoxic potential, but that there is no unanimity in the publications about which local anesthetic is the least or the most neurotoxic.

Nonbiologic Injections in Sports Medicine

Nonbiologic medications (local anesthetics, corticosteroids, and nonsteroidal anti-inflammatory drugs) are commonly administered to athletes for analgesia after injury. However, the risks of nonbiologic injections often are overlooked simply because of their long-term market availability. A thorough understanding of the mechanism of action, the reported benefits, and the potential risks of nonbiologic medications is crucial prior to their use, especially in the treatment of young athletes. Sports medicine physicians and surgeons must be aware of the systemic and local effects of these medications to ensure an appropriate drug choice that minimizes side effects and avoids recently reported toxicity to myocytes, tenocytes, and chondrocytes.

Prolotherapy vs Radial Extracorporeal Shock Wave Therapy in the Short-term Treatment of Lateral Epicondylosis: A Randomized Clinical Trial

OBJECTIVE

The aim of this study was to compare the efficacy of prolotherapy with hypertonic dextrose and radial shock wave therapy in chronic lateral epicondilosis.

DESIGN

Prospective single-blind randomized clinical trial.

SETTING

Physical medicine and rehabilitation clinic.

SUBJECTS

Thirty-three patients with at least three months of signs and symptoms of lateral epicondilosis, as well as failure of at least one of the conservative treatments, randomly allocated into two groups.

METHODS

Sixteen patients received three sessions of shock wave therapy, and 17 received one session prolotherapy. Severity of pain via visual analog scale (VAS), grip strength via Baseline Pneumatic Dynamometer, pressure pain threshold (PPT) by algometer and Disabilities of Arm, Shoulder, and Hand quick questionnaire (Quick DASH) were assessed at baseline, four weeks, and eight weeks after the intervention.

RESULTS

Within-group analysis showed that in both groups, differences between all of the outcome measures were significant after four and also eight weeks. Between-group analysis after four and eight weeks showed that the VAS and Quick DASH had significantly more improvement in the shock wave group. However, the two groups were similar regarding grip strength and PPT. No complication was observed in the two groups.

CONCLUSIONS

Based on the results of this study, a regiment of three sessions (weekly) of radial extracorporeal shock wave therapy is significantly more effective than one session of prolotherapy with 20% dextrose regarding pain and function in the management of chronic lateral epicondylosis in short-term follow-up.

Rotator Cuff-Related Shoulder Pain: To Inject or Not to Inject?

The most common source of shoulder pain is thought to involve the tendons of the rotator cuff and associated structures around the subacromial space. A generic diagnostic term has been suggested, rotator cuff-related shoulder pain (RCRSP), which is an overarching clinical term that includes a number of conditions, such as subacromial impingement syndrome, subacromial pain syndrome, and rotator cuff tendinopathy. The management of RCRSP may include exercise, surgery, or injection therapy. Those who perform or recommend injection therapy for RCRSP have a duty of care to provide advice on the expected benefits and outcomes, as well as the potential risks and associated harms. Clinicians also need to consider what medication to inject, where to inject it, and how to inject it. The aim of this Viewpoint is to discuss these issues. J Orthop Sports Phys Ther 2019;49(5):289-293. doi:10.2519/jospt.2019.0607.

Injections Prior to Rotator Cuff Repair Are Associated With Increased Rotator Cuff Revision Rates

PURPOSE

To determine whether shoulder injections prior to rotator cuff repair (RCR) are associated with deleterious surgical outcomes.

METHODS

Two large national insurance databases were used to identify a total of 22,156 patients who received ipsilateral shoulder injections prior to RCR. They were age, sex, obesity, smoking status, and comorbidity matched to a control group of patients who underwent RCR without prior injections. The 2 groups were compared regarding RCR revision rates.

RESULTS

Patients who received injections prior to RCR were more likely to undergo RCR revision than matched controls (odds ratio [OR], 1.52; 95% confidence interval [CI], 1.38-1.68; P < .0001). Patients who received injections closer to the time of index RCR were more likely to undergo revision (P < .0001). Patients who received a single injection prior to RCR had a higher likelihood of revision (OR, 1.25; 95% CI, 1.10-1.43; P = .001). Patients who received 2 or more injections prior to RCR had a greater than 2-fold odds of revision (combined OR, 2.12; 95% CI, 1.82-2.47; P < .0001) versus the control group.

CONCLUSIONS

This study strongly suggests a correlation between preoperative shoulder injections and revision RCR. There is also a frequency dependence and time dependence to this finding, with more frequent injections and with administration of injections closer to the time of surgery both independently associated with higher revision RCR rates. Presently, on the basis of this retrospective database study, orthopaedic surgeons should exercise due caution regarding shoulder injections in patients whom they are considering to be surgical candidates for RCR.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Preoperative Shoulder Injections Are Associated With Increased Risk of Revision Rotator Cuff Repair

PURPOSE

The goal of this study was to determine whether the timing of preoperative shoulder injections is associated with an increased risk of revision rotator cuff repair following primary rotator cuff repair (RCR).

METHODS

A retrospective analysis of claims data of privately insured subjects from the MarketScan database for the years 2010 to 2014 was conducted. Multivariable logistic regression models were used to compare the odds of reoperation between groups. Laterality for the injection, index procedure, and subsequent surgery were verified for all subjects.

RESULTS

A total of 4,959 subjects with an arthroscopic RCR were identified, 392 of whom required revision RCR within the following 3 years. Patients who had an injection within 6 months preceding the index surgery were at a much higher risk of undergoing reoperation for revision RCR: 0 to 3 months prior, adjusted odds ratio (AOR) 1.375 (95% confidence interval [CI], 1.027-1.840); 3 to 6 months prior, AOR 1.822 (95% CI, 1.290-2.573); and 6 to 12 months prior, AOR 1.237 (95% CI, 0.787-1.943).

CONCLUSIONS

Patients who had received an injection within 6 months prior to RCR were much more likely to undergo a revision cuff repair within the following 3 years. The risk of reoperation significantly declines if there is more than 6 months between injection and RCR. Consideration should be given to minimizing preoperative injections in patients requiring RCR or delaying primary RCR for 6 months following injection.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Effects of Estrogen-Deficient State on Rotator Cuff Healing

BACKGROUND

Rotator cuff retears after surgical repair are a concern, despite advances in operative techniques, but few studies have investigated the effects of the estrogen-deficient state on tendon-to-bone healing at the repair site.

PURPOSE

We evaluated the effect of the estrogen-deficient state on tendon-to-bone healing after rotator cuff repair in an ovariectomized rat model.

STUDY DESIGN

Controlled laboratory study.

METHODS

Female Sprague Dawley rats underwent detachment and immediate repair of the supraspinatus tendon. Surgery was performed in 24 rats at 4.5 weeks of age 17 weeks after ovariectomy (OVX group) and in 24 age-matched control rats without ovariectomy (control group). Animals were sacrificed at 2, 4, 8, and 12 weeks after surgery for biomechanical and histological evaluations of reattachment. Bone mineral density (BMD) at the insertion site and cancellous bone in the humeral head was assessed by micro-computed tomography.

RESULTS

BMD was significantly lower both at the insertion site and in cancellous area in the OVX group than in the control group at weeks 2 to 12. Ultimate load to failure, ultimate stress, linear stiffness, and the Young modulus were significantly lower in the OVX group than in the control group at 2 and 4 weeks, but the difference was no longer significant at 8 and 12 weeks. At 2 and 4 weeks, relatively immature granulation tissue was observed in the OVX group compared with the control group. At 8 and 12 weeks after surgery, there were differences in the tendon-bone interface in the 2 groups: Direct insertion with well-established chondroid tissue was seen in the control group, and indirect insertion without chondroid tissue was seen in the OVX group. Consistently, the amount of chondroid tissue was greater and collagen organization was better in the control group than in the OVX group. Cells expressing cathepsin K were significantly more numerous both at the insertion site and in cancellous bone in the OVX group than in the control group.

CONCLUSION

The estrogen-deficient state by ovariectomy, compared with control rats, led to decreased biomechanical properties and poor development of chondroid tissue that influenced the repair of the tendon insertion after surgery.

CLINICAL RELEVANCE

Agents that modulate bone metabolism might improve tendon-to-bone healing in patients with an estrogen-deficient state, such as postmenopausal women who undergo rotator cuff surgery.

Protective effects of platelet-rich plasma against lidocaine cytotoxicity on canine articular chondrocytes

Background

Lidocaine (LD) is one of the most commonly used local anesthetics for performing arthroscopic surgery and managing of osteoarthritic pain in both human and veterinary medicine. However, over the last years, several studies have focused on the chondrotoxic effects of LD. In order to ensure that intra-articular lidocaine is safe to use, treatments aimed at mitigating chondrocyte death have recently been investigated. The aim of this study is to evaluate the possible protective effects of platelet-rich plasma (PRP) against LD cytotoxicity on canine articular chondrocytes.

Results

Articular canine chondrocytes, were exposed to 1% or 1.8% LD alone or in co-presence with 10% PRP for 30 min. In order to evaluate the effects of PRP pre-treatments, experiments were carried out on cells cultured in serum-free medium-or in medium supplemented with 10% PRP or 10% fetal bovine serum. Cell viability was evaluated by methyl thiazolyl tetrazolium assay and cell apoptosis was analyzed by flow cytometry using annexin V-fluorescein isothiocyanate/propidium iodide. The results showed that LD significantly reduced canine chondrocytes viability, probably due to apoptosis induction. Pre-treatment or the co-presence of PRP in the media restored the number of viable chondrocytes. The PRP also seemed to protect the cells from LD-induced apoptosis.

Conclusions

Pre-treatments and/or the simultaneous administration of PRP reduced LD-induced cytotoxicity in canine chondrocytes. Further in vivo studies are required to determine whether PRP can be used as a save protective treatment for dogs receiving intra-articular LD injections.

Three-dimensional ultrastructural analysis and histomorphometry of collagen bundles in the periodontal ligament using focused ion beam/scanning electron microscope tomography

BACKGROUND AND OBJECTIVE

The periodontal ligament (PDL) is an essential tissue for tooth function. However, the 3-dimensional ultrastructure of these PDL collagen bundles on a mesoscale is not clear. We investigated the 3-dimensional ultrastructure of these collagen bundles and quantitatively analyzed their histomorphometry using focused ion beam/scanning electron microscope (FIB/SEM) tomography.

MATERIAL AND METHODS

The PDLs of the first mandibular molar of male C57BL/6 mice were analyzed using FIB/SEM tomography. The serial images of the collagen bundles so obtained were reconstructed. The collagen bundles were analyzed quantitatively using 3-dimensional histomorphometry.

RESULTS

Collagen bundles of the PDL demonstrated multiple branched structures, rather than a single rope-like structure, and were wrapped in cytoplasm sheets. The structure of the horizontal fiber of the collagen bundle was an extensive meshwork. In contrast, the oblique and apical fibers of the collagen bundle showed a chain-like structure. The area and the minor and major axis lengths of cross-sections of the horizontal fiber, as determined from 3-dimensional images, were significantly different from those of the oblique and apical fibers.

CONCLUSION

These findings indicate that collagen bundles in horizontal fiber areas have high strength and that the tooth is firmly anchored to the alveolar bone by the horizontal fibers, but is not secured evenly to the alveolar bone. The tooth is firmly anchored around the cervical area, creating a "slingshot-like structure." This study has provided further insights into the structure of the PDL and forms the basis for the development of more effective therapies for periodontal tissue regeneration.

Are corticosteroid injections more beneficial than anaesthetic injections alone in the management of rotator cuff-related shoulder pain? A systematic review

Objective

To compare the effectiveness of corticosteroid injections to local anaesthetic injections in the management of rotator cuff-related shoulder pain (RCRSP).

Design

Systematic review with best evidence synthesis.

Data sources

The Cochrane, PubMed, CINAHL Plus, PEDro and EMBASE electronic databases were searched (inception until 8 June 2017). Reference lists of included articles were also hand searched.

Eligibility criteria

Two reviewers independently evaluated eligibility. Randomised controlled trials (RCTs) were included if they compared subacromial injections of corticosteroid with anaesthetic injections. Two reviewers independently extracted data regarding short-term, midterm and long-term outcomes for pain, self-reported function, range of motion and patient-perceived improvement.

Results

Thirteen RCTs (n=1013) were included. Four trials (n=475) were judged as being at low risk of bias. Three studies of low risk of bias favoured the use of corticosteroid over anaesthetic-only injections in the short term (up to 8 weeks). There was strong evidence of no significant difference between injection types in midterm outcomes (12–26 weeks). There was limited evidence of no significant difference between injection types in long-term outcomes.

Conclusion

Corticosteroid injections may have a short-term benefit (up to 8 weeks) over local anaesthetic injections alone in the management of RCRSP. Beyond 8 weeks, there was no evidence to suggest a benefit of corticosteroid over local anaesthetic injections.

Trial registration number

PROSPERO CRD42016033161.

Hyaluronic Acid Accelerates Tendon-to-Bone Healing After Rotator Cuff Repair

BACKGROUND

There is growing evidence that the subacromial injection of hyaluronic acid (HA) is effective for pain relief in rotator cuff tears; however, its effect on tendon-to-bone healing remains unknown.

PURPOSE

To examine the effect of HA on the chondrogenesis of mesenchymal stem cells (MSCs) in vitro and on tendon-to-bone healing in a rotator cuff repair model.

STUDY DESIGN

Controlled laboratory study.

METHODS

Bilateral complete tears of the infraspinatus tendon were made in rabbits and subsequently repaired. Before closure, 1 mL HA was applied to the repaired site, and phosphate-buffered saline was used in the opposite side as a control. Biomechanical, histological, and immunohistochemical analyses were performed at 4, 8, and 12 weeks after surgery. After euthanizing each animal, the bone marrow was isolated from the femoral bone in the same rabbits. Then, MSCs were cultured in media for chondrogenic differentiation, and the chondral pellet production and cartilage-related gene expression levels in the cells were examined at various concentrations of HA.

RESULTS

At 4 and 8 weeks after surgery, ultimate load-to-failure was significantly greater in the HA group than in the control group (45.61 ± 9.0 N vs 32.42 ± 9.4 N at 4 weeks, 90.7 ± 16.0 N vs 66.97 ± 10.0 N at 8 weeks; both P < .05) but not at 12 weeks after surgery (109.6 ± 40.2 N vs 108.1 ± 42.6 N, P > .05). Linear stiffness was not significant throughout the time point evaluation. The chondroid formation area at the tendon-bone interface stained by safranin O (control vs HA group) was 0.33% ± 0.7% versus 13.5% ± 12.3% at 4 weeks after surgery ( P < .05) and 3.0% ± 5.9% versus 12.9% ± 12.9% at 8 weeks after surgery ( P < .05), but there was no significant difference at 12 weeks after surgery. Maturity of collagen at the repaired site stained by PicroSirius Red (control vs HA group) was 16.2 ± 10.6 versus 43.5 ± 21.3 at 4 weeks after surgery ( P < .05), but there were no significant differences at 8 and 12 weeks after surgery. MSCs were cultured in media for chondrogenic differentiation, and the chondral pellet production and cartilage-related gene expression levels in the cells were examined at various concentrations of HA. The number of CD44-positive cells (control vs HA group) was 8.3% ± 1.4% versus 26.2% ± 5.2% at 3 days after surgery ( P < .05), 1.8% ± 1.1% versus 26.6% ± 11.6% at 4 weeks after surgery ( P < .05), 0.6% ± 0.9% versus 0.5% ± 0.6% at 8 weeks after surgery ( P > .05), and 1.8% ± 4.0% versus 5.4% ± 4.2% at 12 weeks after surgery ( P > .05). Compared with the control group, HA significantly increased the volume of cartilaginous pellet produced by MSCs (0.0016 ± 0.0015 mm³ at 0 mg/mL of HA, 0.0041 ± 0.0023 mm³ at 1.0 mg/mL, and 0.0041 ± 0.0018 mm³ at 4.0 mg/mL), with increased mRNA expression (relative ratio to control) of type 2 collagen (1.34 ± 0.38), SOX9 (1.58 ± 0.31), and aggrecan (1.30 ± 0.22) genes in the pellet ( P < .01).

CONCLUSION

HA accelerated tendon-to-bone healing in the rotator cuff repair model, enhancing the biomechanical strength and increasing chondroid formation and tendon maturity at the tendon-bone interface. Based on the data of in vitro experiments, HA-activated MSCs may play a crucial role in the acceleration of tendon-to-bone healing.

CLINICAL RELEVANCE

The data suggest the relevance of clinical application of HA to accelerate tendon-to-bone healing. It may decrease the number of retears after surgery.

Comparison Between Corticosteroid and Lidocaine Injection in the Treatment of Tennis Elbow: A Randomized, Double-Blinded, Controlled Trial

OBJECTIVE

The aim of the study was to compare the effects of corticosteroid injection with lidocaine injection in treating tennis elbow.

DESIGN

It is a prospective, double-blinded, randomized controlled trial. Patients with tennis elbow for more than 1 mo were recruited from a hospital-based rehabilitation outpatient clinic. A total of 70 patients were recruited, and 61 patients completed the study. Patients received an injection of either 10 mg (1 ml) of triamcinolone (corticosteroid group, n = 30) or 1 ml of 1% lidocaine (lidocaine group, n = 31). All of the outcome measures were evaluated before the intervention and at 2 wks and 2 mos after treatment.

RESULTS

No significant group differences were observed between the corticosteroid and lidocaine groups regarding Patient-Rated Tennis Elbow Evaluation, Disability of the Arm, Shoulder, and Hand, visual analog scale for pain, and grip strength at baseline and at 2 wks and 2 mos after treatment (P > 0.05). However, within-group comparison showed significant improvement after injection with regard to Patient-Rated Tennis Elbow Evaluation, Disability of the Arm, Shoulder, and Hand, visual analog scale for pain, and grip strength in both groups (P > 0.05).

CONCLUSIONS

No differences in the short-term outcomes were found between lidocaine and corticosteroid injection in a small sample of people with tennis elbow with mean duration of 3.8 mos.

Apoptosis and rotator cuff tears: scientific evidence from basic science to clinical findings

INTRODUCTION

Excessive apoptosis has been hypothesized as possible cause of tendinopathy and tear in the tendons of the rotator cuff (RC). Different mechanisms and molecules play a key role in cell regulation. Biological interventions can affect the process of apoptosis to control the tendinopathy process, and may be useful to design new treatments.

SOURCE OF DATA

We identified basic science, in vitro and in vivo preclinical and clinical studies listed in the Pubmed Google Scholar, CINAHL, Cochrane Central and Embase Biomedical databases in English, Spanish, Italian and French concerning the effects of apoptosis on RC tendons.

AREAS OF AGREEMENT

The homeostasis between the apoptotic and inflammatory processes is dynamic and controlled by pro- and anti-apoptotic mechanisms and signals, with variable balance in different areas of the RC tendons in human specimens.

AREAS OF CONTROVERSY

Apoptosis can be identified along the whole tendon, not only in the area of the lesion. Therefore, it is not necessary to undertake wide debridement of the torn edges of the tendon when undertaking a repair.

GROWING POINTS

The identification of the various factors that control apoptosis and its mechanisms can help to design new treatments and exert positive effects in the recovery from tendon tears.

AREAS TIMELY FOR DEVELOPING RESEARCH

Further studies are needed to produce clear guidelines to determine how to balance the apoptosis process to reduce the failed healing response found in non-traumatic RC tears.

Mini-Review: Toxic Tendinopathy

Toxic tendinopathy is a rare but reproducible complication in humans, given agents of four drug classes: aromatase inhibitors, fluoroquinolone antibiotics, glucocorticoids (long-term regimens), and statins. Toxic tendinopathy in humans has been linked less consistently to treatment with anabolic steroids, antiretroviral agents (mainly protease inhibitors), metalloproteinase inhibitors (MMPI), and isotretinoin. Classic drug-induced tendinopathies appear as "tendinosis" (i.e., progressive tendon degeneration without inflammation), although cases associated with aromatase inhibitors exhibit mainly tenosynovitis. Any tendon may be affected, but fluoroquinolones, glucocorticoids, and statins most frequently affect large load-bearing tendons in the lower limb, especially the calcaneal ("Achilles") tendon-which ruptures in approximately 30 to 40% of cases. The time to symptom onset ranges from days (fluoroquinolones) to weeks, months, or even years. The pathogenesis is incompletely understood, but proposed mechanisms include apoptosis of tenoblasts and tenocytes, deficient tenocyte function (leading to abnormal extracellular matrix maintenance and repair as well as disrupted intercellular signaling), and structural disintegration (via a combination of increased expression of lytic enzymes, lessened cholesterol content in cell membranes, and neoangiogenesis within highly ordered tendon tissue). Nonclinical safety assessment of therapeutic candidates in these drug classes should incorporate tendon routinely as a protocol-specified tissue for pathology evaluation.

Histomorphometric and ultrastructural analysis of the tendon-bone interface after rotator cuff repair in a rat model

Successful rotator cuff repair requires biological anchoring of the repaired tendon to the bone. However, the histological structure of the repaired tendon-bone interface differs from that of a normal tendon insertion. We analysed differences between the normal tendon insertion and the repaired tendon-bone interface after surgery in the mechanical properties, histomorphometric analysis, and 3-dimensional ultrastructure of the cells using a rat rotator cuff repair model. Twenty-four adult Sprague-Dawley (SD) rats underwent complete cuff tear and subsequent repair of the supraspinatus tendon. The repaired tendon-bone interface was evaluated at 4, 8, and 12 weeks after surgery. At each time point, shoulders underwent micro-computed tomography scanning and biomechanical testing (N = 6), conventional histology and histomorphometric analysis (N = 6), and ultrastructural analysis with focused ion beam/scanning electron microscope (FIB/SEM) tomography (N = 4). We demonstrated that the cellular distribution between the repaired tendon and bone at 12 weeks after surgery bore similarities to the normal tendon insertion. However, the ultrastructure of the cells at any time point had a different morphology than those of the normal tendon insertion. These morphological differences affect the healing process, partly contributing to re-tearing at the repair site. These results may facilitate future studies of the regeneration of a normal tendon insertion.