Efficacy of Adjuvant Application of Platelet-Rich Plasma After Needle Aspiration of Calcific Deposits for the Treatment of Rotator Cuff Calcific Tendinitis: A Double-Blinded, Randomized Controlled Trial With 2-Year Follow-up

Studies With Direct Industry Affiliation Are More Likely to Report Positive Results in Randomized Controlled Trials for Platelet-Rich Plasma Use in Rotator Cuff Tears: A Systematic Review

PURPOSE

To perform a systematic review to evaluate the effect of industry affiliation on the outcomes of randomized controlled trials for platelet-rich plasma (PRP) injections in rotator cuff tears METHODS: The PubMed, SPORTDiscus, and Scopus databases were searched from 2010 to the present for the terms "rotator cuff" and "platelet-rich plasma." The inclusion criteria were randomized controlled trials comparing PRP with controls for the treatment of rotator cuff tears, and the exclusion criteria were systematic reviews, meta-analyses, case reports, cohort studies, basic science studies, studies of Level III or below, and studies not in English. Degree of industry affiliation was categorized into 3 groups: directly, indirectly, and not affiliated. Direct affiliation required the study or its authors to receive financial support from the company manufacturing the devices used in the study to prepare or administer PRP. Indirect affiliation required financial association with a different company that produces or administers PRP than the company in the study. Studies were classified as favorable if study outcomes achieved significance (P < .05) of PRP over controls or as analogous if there was no statistical significance between PRP and controls. Data were analyzed using the χ2 test and Fisher exact test.

RESULTS

Of the 47 studies selected for analysis, 8 (17.0%) had no direct industry affiliation; 9 (19.1%) had indirect affiliation; and 30 (63.8%) had no industry affiliation. Of the studies, 22 (46.8%) reported favorable results with PRP compared with controls and 25 (53.2%) showed analogous results between PRP and controls. Degree of industry affiliation was significantly associated with an increased likelihood of reporting favorable study outcomes (P = .041). Directly affiliated studies had a significantly increased likelihood of reporting favorable results (P = .024) compared with indirectly affiliated studies.

CONCLUSIONS

Studies that used PRP produced by companies that directly funded the studies or were financially affiliated with the authors were significantly more likely to report favorable results.

LEVEL OF EVIDENCE

Level II, systematic review of Level I and II studies.

Platelet-Rich Plasma Versus Corticosteroid Injections for Chronic Tendinopathies: A Systematic Review and Meta-Analysis

Chronic tendinopathy is a degenerative condition characterized by persistent pain, functional limitations, and tendon thickening, often resulting from repetitive overuse or failed tendon healing. Left untreated, it can progress to tendon rupture, prolonged disability, and impaired quality of life. Management typically includes conservative therapies, such as physical therapy, corticosteroid (CS) injections for short-term relief, and platelet-rich plasma (PRP) as a regenerative therapy with potential long-term benefits. This systematic review and meta-analysis evaluates and compares the effectiveness of PRP and CS injections for chronic tendinopathies regarding pain reduction, functional improvement, and long-term outcomes. A structured search of PubMed, Scopus, Google Scholar, and the Cochrane Library identified randomized controlled trials (RCTs) and comparative studies. Primary outcomes included pain reduction and functional improvement while secondary outcomes assessed heterogeneity and publication bias. PRP and CS injections demonstrated no significant difference in short-term pain reduction. Functional outcomes were comparable in the short term but showed a trend favoring PRP at longer follow-up periods. PRP exhibited a slight advantage in long-term functional recovery, though the results were not statistically significant. Substantial heterogeneity across studies highlights the need for standardized protocols and larger trials to confirm these findings and optimize treatment strategies.

Effect of extracorporeal shock wave combined with autologous platelet-rich plasma injection on rotator cuff calcific tendinitis: study protocol for a randomized controlled trial

BACKGROUND

Rotator cuff calcific tendinitis (RCCT) is a common shoulder disease whose main symptoms include shoulder pain, limited mobility, and calcification deposits in the shoulder. Traditional treatment methods have certain limitations, so finding new treatment methods has become the focus of research. Extracorporeal shock wave (ESW) and platelet-rich plasma (PRP) treatments have attracted much attention due to their non-invasive and tissue repair-promoting properties; however, the efficacy of their combined treatment in RCCT remains unclear.

METHODS

This study is designed as a single-center, assessment-blind, randomized controlled clinical trial with three parallel groups. Sixty subjects will be recruited and randomly divided into the ESW group, PRP group, and ESW combined with PRP group, in a 1:1:1 ratio. The entire intervention period is 4 weeks, and the follow-up period is 4 weeks. Outcomes will be measured at baseline (T0), after 1 week of intervention (T1), after 2 weeks of intervention (T2), after 4 weeks of intervention (T3), and after an additional 4 weeks of follow-up period (T4). The primary endpoint is the VAS score. Secondary endpoints are ASES, CMS, UCLA, and the location and size of calcified areas.

DISCUSSION

This study aims to evaluate the efficacy of ESW therapy combined with PRP in treating RCCT. We compare the effects of single and combined treatments to explore their impact on disease symptoms, functional improvement, and calcification regression. This provides a scientific basis for identifying more effective treatment options.

TRIAL REGISTRATION

ClinicalTrials.gov NCT06372600. Registered on April 17, 2024; version 1.

Systematic literature review to inform the EULAR recommendations for the use of imaging in crystal-induced arthropathies in clinical practice

OBJECTIVE

To summarise current data regarding the use of imaging in crystal-induced arthropathies (CiAs) informing a European Alliance of Associations for Rheumatology task force.

METHODS

We performed four systematic searches in Embase, Medline and Central on imaging for diagnosis, monitoring, prediction of disease severity/treatment response, guiding procedures and patient education in gout, calcium pyrophosphate dihydrate deposition (CPPD) and basic calcium phosphate deposition (BCPD). Records were screened, manuscripts reviewed and data of the included studies extracted. The risk of bias was assessed by validated instruments.

RESULTS

For gout, 88 studies were included. Diagnostic studies reported good to excellent sensitivity and specificity of dual-energy CT (DECT) and ultrasound (US), high specificity and lower sensitivity for conventional radiographs (CR) and CT. Longitudinal studies demonstrated sensitivity to change with regard to crystal deposition by US and DECT and inflammation by US and structural progression by CR and CT. For CPPD, 50 studies were included. Diagnostic studies on CR and US showed high specificity and variable sensitivity. There was a single study on monitoring, while nine assessed the prediction in CPPD. For BCPD, 56 studies were included. There were two diagnostic studies, while monitoring by CR and US was assessed in 43 studies, showing a reduction in crystal deposition. A total of 12 studies with inconsistent results assessed the prediction of treatment response. The search on patient education retrieved two studies, suggesting a potential role of DECT.

CONCLUSION

This SLR confirmed a relevant and increasing role of imaging in the field of CiAs.

Common treatment strategies for calcium hydroxyapatite deposition disease: a cost-effectiveness analysis

OBJECTIVE

To determine the cost-effectiveness of rotator cuff hydroxyapatite deposition disease (HADD) treatments.

METHOD

A 1-year time horizon decision analytic model was created from the US healthcare system perspective for a 52-year-old female with shoulder HADD failing conservative management. The model evaluated the incremental cost-effectiveness ratio (ICER) and net monetary benefit (NMB) of standard strategies, including conservative management, ultrasound-guided barbotage (UGB), high- and low-energy extracorporeal shock wave therapy (ECSW), and surgery. The primary effectiveness outcome was quality-adjusted life years (QALY). Costs were estimated in 2022 US dollars. The willingness-to-pay (WTP) threshold was $100,000.

RESULTS

For the base case, UGB was the preferred strategy (0.9725 QALY, total cost, $2199.35, NMB, $95,048.45, and ICER, $33,992.99), with conservative management (0.9670 QALY, NMB $94,688.83) a reasonable alternative. High-energy ECSW (0.9837 QALY, NMB $94,805.72), though most effective, had an ICER of $121, 558.90, surpassing the WTP threshold. Surgery (0.9532 QALY, NMB $92,092.46) and low-energy ECSW (0.9287 QALY, NMB $87,881.20) were each dominated. Sensitivity analysis demonstrated that high-energy ECSW would become the favored strategy when its cost was < $2905.66, and conservative management was favored when the cost was < $990.34. Probabilistic sensitivity analysis supported the base case results, with UGB preferred in 43% of simulations, high-energy ECSW in 36%, conservative management in 20%, and low-energy ECSW and surgery in < 1%.

CONCLUSION

UGB appears to be the most cost-effective strategy for patients with HADD, while surgery and low-energy ECSW are the least cost-effective. Conservative management may be considered a reasonable alternative treatment strategy in the appropriate clinical setting.

Treatment of Tendon Injuries in the Servicemember Population across the Spectrum of Pathology: From Exosomes to Bioinductive Scaffolds

Tendon injuries in military servicemembers are one of the most commonly treated nonbattle musculoskeletal injuries (NBMSKIs). Commonly the result of demanding physical training, repetitive loading, and frequent exposures to austere conditions, tendon injuries represent a conspicuous threat to operational readiness. Tendon healing involves a complex sequence between stages of inflammation, proliferation, and remodeling cycles, but the regenerated tissue can be biomechanically inferior to the native tendon. Chemical and mechanical signaling pathways aid tendon healing by employing growth factors, cytokines, and inflammatory responses. Exosome-based therapy, particularly using adipose-derived stem cells (ASCs), offers a prominent cell-free treatment, promoting tendon repair and altering mRNA expression. However, each of these approaches is not without limitations. Future advances in tendon tissue engineering involving magnetic stimulation and gene therapy offer non-invasive, targeted approaches for improved tissue engineering. Ongoing research aims to translate these therapies into effective clinical solutions capable of maximizing operational readiness and warfighter lethality.

Pristimerin suppresses AIM2 inflammasome by modulating AIM2-PYCARD/ASC stability via selective autophagy to alleviate tendinopathy

Macroautophagy/autophagy plays an important role in regulating cellular homeostasis and influences the pathogenesis of degenerative diseases. Tendinopathy is characterized by tendon degeneration and inflammation. However, little is known about the role of selective autophagy in tendinopathy. Here, we find that pristimerin (PM), a quinone methide triterpenoid, is more effective in treating tendinopathy than the first-line drug indomethacin. PM inhibits the AIM2 inflammasome and alleviates inflammation during tendinopathy by promoting the autophagic degradation of AIM2 through a PYCARD/ASC-dependent manner. A mechanistic study shows that PM enhances the K63-linked ubiquitin chains of PYCARD/ASC at K158/161, which serves as a recognition signal for SQSTM1/p62-mediated autophagic degradation of the AIM2-PYCARD/ASC complex. We further identify that PM binds the Cys53 site of deubiquitinase USP50 through the Michael-acceptor and blocks the binding of USP50 to PYCARD/ASC, thereby reducing USP50-mediated cleavage of K63-linked ubiquitin chains of PYCARD/ASC. Finally, PM treatment in vivo generates an effect comparable to inflammasome deficiency in alleviating tendinopathy. Taken together, these findings demonstrate that PM alleviates the progression of tendinopathy by modulating AIM2-PYCARD/ASC stability via SQSTM1/p62-mediated selective autophagic degradation, thus providing a promising autophagy-based therapeutic for tendinopathy.Abbreviations: 3-MA: 3-methyladenine; AIM2: absent in melanoma 2; AT: Achilles tenotomy; ATP: adenosine triphosphate; BMDMs: bone marrow-derived macrophages; CHX: cycloheximide; Col3a1: collagen, type III, alpha 1; CQ: chloroquine; Cys: cysteine; DARTS: drug affinity responsive target stability; DTT: dithiothreitol; DUB: deubiquitinase; gDNA: genomic DNA; GSH: glutathione; His: histidine; IL1B/IL-1β: interleukin 1 beta; IND: indomethacin; IP: immunoprecipitation; LPS: lipopolysaccharide; MMP: mitochondrial membrane potential; NLRP3: NLR family, pyrin domain containing 3; PM: pristimerin; PYCARD/ASC: PYD and CARD domain containing; SN: supernatants; SOX9: SRY (sex determining region Y)-box 9; SQSTM1: sequestosome 1; Tgfb: transforming growth factor, beta; TIMP3: tissue inhibitor of metalloproteinase 3; TNMD: tenomodulin; TRAF6: TNF receptor-associated factor 6; Ub: ubiquitin; USP50: ubiquitin specific peptidase 50; WCL: whole cell lysates.

Treatment of Calcific Tendonitis of the Rotator Cuff: An Updated Review

Rotator cuff calcific tendonitis (RCCT) is a disorder that can greatly impair patients' quality of life. A literature review was conducted to find the most effective and newest treatments for RCCT. PubMed and Cochrane Review databases were searched, without strict inclusion/exclusion criteria, for peer-reviewed articles between 1941 and 2021 that discussed RCCT etiology and treatments. If nonoperative measures (non-steroidal anti-inflammatory drugs, physical therapy, and corticosteroids) are unsuccessful, other options include extracorporeal shockwave therapy, ultrasound-guided injection techniques, and minimally invasive surgery. Because RCCT can resolve spontaneously, patients should progress to invasive options only if conservative first-line treatments have failed. [Orthopedics. 2023;46(6):e326-e332.].

Current Status and Advancements in Platelet-Rich Plasma Therapy

Platelet-rich plasma (PRP) as a treatment modality has been around for the last four decades, but only truly gained popularity over the last 10 to 15 years in medicine, in a variety of fields ranging from regenerative medicine to infertility treatment. It has gained popularity, especially in treating musculoskeletal conditions where the bulk of research has been performed and published. There is level I evidence available supporting its efficacy in the treatment of osteoarthritis (OA), epicondylitis, bursitis, compressive neuropathy, plantar fasciitis, muscular injuries and osteochondral lesions. Most published research with regards to PRP has been focused on knee OA (limited research in shoulder, elbow, and foot and ankle OA), lateral epicondylitis and carpal tunnel syndrome, whereas spinal and hand conditions have limited research available. Tendinopathies and partial tendon tears have conflicting evidence available, with level I evidence supporting PRP's use in rotator cuff tendinopathies and tears, with contradictory level I evidence discouraging its use in patella and Achilles tendinopathies and tears. The available evidence regarding the use of PRP continues to produce conflicting results, but despite this, there is an ongoing increase in the popularity and use of PRP in patients with musculoskeletal conditions.

Role of platelet-rich plasma in the treatment of rotator cuff tendinopathy

Shoulder pain is a common musculoskeletal complaint, and rotator cuff (RC) pathologies are one of the main causes. The RC undergoes various tendinopathic and avascular changes during the aging process. Other degenerative changes affecting its healing potential make it an appealing target for biological agents. Platelet-rich plasma (PRP) has demonstrated the potential to deliver a high concentration of several growth factors and anti-inflammatory mediators, and its clinical use is mainly supported by experiments that demonstrated its positive effect on muscle, ligaments, and tendinous cells. This review aimed to specify the role of PRP and its future applications in RC tendinopathies based on the current clinical evidence. Due to the different characteristics and conflicting outcomes, clinicians should use PRP with moderate expectations until more consistent evidence is available. However, it is reasonable to consider PRP in patients with contraindications to corticosteroid injections or those with risk factors for inadequate healing. Its autologous origin makes it a safe treatment, and its characteristics make it a promising option for treating RC tendinopathy, but the efficacy has yet to be established.

Effects of adjuvant application of corticosteroid and ozone after ultrasound-guided puncture and lavage for the treatment of rotator cuff calcific tendinitis: study protocol for a non-inferiority randomized controlled trial

BACKGROUND

Steroid injection after percutaneous irrigation of calcific deposits is a common method for the treatment of rotator cuff calcific tendinitis (RCCT). However, steroids may prevent calcification resorption and cause potentially irreversible damage to tendons. Recent studies have confirmed the positive effects of ozone injection in shoulder tendinopathies, but no RCCTs have been reported. Thus, our study aims to evaluate the non-inferiority of ozone versus steroid injection.

METHODS

This is a prospective, randomized, parallel control and non-inferiority trial. A total of 100 patients with unilateral symptomatic RCCT will be enrolled and randomized in a 1:1 ratio to two groups: ultrasound-guided injection with ozone or corticosteroid. The primary outcome is the numeric rating scale for pain (NRS) at 1 week and 3 months following the procedure. Secondary outcomes include a multi-dimensional evaluation of shoulder disability and quality of life improvement, the degree of calcification absorption after treatment, and the number of multiple treatments.

DISCUSSION

The results of this study will provide short-term and long-term evidence for the effectiveness of ozone treatment in RCCT in relieving pain or improving shoulder function.

TRIAL REGISTRATION

Chinese Clinical Trial Registry ChiCTR2200063469. Registered on 7 September 2022.

Plasma rich in growth factors versus corticosteroid injections for management of chronic rotator cuff tendinopathy: a prospective double-blind randomized controlled trial with 1 year of follow-up

BACKGROUND

Rotator cuff tendinopathy (RCT) is a painful and dysfunctional shoulder condition traditionally considered as a degenerative pathology. However, evidence is pointing to immunocompetent cells and activated stromal fibroblasts as the drivers of a nonresolved inflammatory condition in RCT. As potent anti-inflammatory agents, corticosteroid injections have been among the first-line and the most common therapeutic strategies. Recently, another adjuvant therapy to treat musculoskeletal inflammation-driven painful conditions, namely, platelet-rich plasma (PRP), has emerged as safe and effective. The aim of this study was to compare the clinical efficacy of intratendinous injections of plasma rich in growth factors (PRGF) with conventional intratendinous corticosteroid injections on patients with chronic RCT using patient-reported outcome measures.

METHODS

A total of 39 patients received PRGF treatment (3 infiltrations, 1 every other week), whereas 40 patients, as a control group, received corticosteroid (3 infiltrations, 1 every other week). Patients were evaluated before treatment and at 3, 6, and 12 months of follow-up using the University of California Los Angeles (UCLA) scale, Quick Disabilities of the Arm, Shoulder and Hand (QuickDASH), and Constant test. The primary outcome of the study was a 15% superior improvement of the PRGF group compared with the corticosteroid group in the UCLA scale and QuickDASH test at 6 months of follow-up, considering this difference to be clinically relevant.

RESULTS

Both PRGF and corticosteroid groups showed significant clinical improvement in the 3 scores at all time points of the study compared with baseline. However, at 6 and 12 months of follow-up, the PRGF group had 22.1% and 21.2% superior improvement of the UCLA test, 14.3% and 13.5% for QuickDASH, and 16.4% and 20.2% for the Constant-Murley test, respectively, compared to the corticosteroid group.

CONCLUSIONS

Three PRGF intratendinous injections every other week in patients with chronic rotator cuff tendinopathy show significantly superior and sustained pain-relieving and functional improvements compared with corticosteroid intratendinous injections assessed by 3 patient-reported outcome scales at 6 and 12 months of follow-up.

Platelet-Rich Plasma Injection Can Be a Viable Alternative to Corticosteroid Injection for Conservative Treatment of Rotator Cuff Disease: A Meta-analysis of Randomized Controlled Trials

PURPOSE

To explore whether platelet-rich plasma (PRP) injection can be a viable alternative to corticosteroid (CS) injection for conservative treatment of rotator cuff disease.

METHODS

This study was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. PubMed, EMBASE, The Cochrane Library, and Web of Science were searched from January 1, 1990, to March 20, 2022, for English-language randomized controlled trials that compared PRP and CS injections for patients with rotator cuff disease. Two evaluators independently screened the literature, extracted data, and assessed the level of evidence and methodologic quality of the enrolled studies. The meta-analysis was conducted using RevMan software (version 5.3.3).

RESULTS

Thirteen nonsurgical randomized controlled trials with 725 patients were included. Compared with CS, PRP provided statistically worse short-term (<2 months) changes in American Shoulder and Elbow Surgeons (ASES) assessment scores, Simple Shoulder Test scores, and Disabilities of the Arm, Shoulder and Hand questionnaire scores but provided better medium-term (2-6 months) changes in Disabilities of the Arm, Shoulder and Hand scores, as well as long-term (≥6 months) changes in Constant-Murley scores, ASES scores, and Simple Shoulder Test scores. No statistically significant differences regarding pain reduction were found between the 2 groups. PRP injections led to worse short-term changes in forward flexion and internal rotation but better medium-term changes in forward flexion and external rotation. PRP showed significantly lower rates of post-injection failure (requests for subsequent injections or surgical intervention prior to 12 months) than CS. No outcome reached the minimal clinically important difference. After sensitivity analyses excluding studies with substantial clinical and/or methodologic heterogeneity, PRP showed better medium-term changes in ASES scores and visual analog scale scores and long-term changes in visual analog scale scores that reached the minimal clinically important difference.

CONCLUSIONS

Without the drawbacks of CS injection, PRP injection is not worse than CS injection in terms of pain relief and function recovery at any time point during follow-up. PRP injection may reduce rates of subsequent injection or surgery, and it might provide better improvements in pain and function in the medium to long term. PRP injection can be a viable alternative to CS injection for conservative treatment of rotator cuff disease.

LEVEL OF EVIDENCE

Meta-analysis of Level I and II studies.

Update on the Use of Platelet-Rich Plasma Injections in the Management of Musculoskeletal Injuries: A Systematic Review of Studies From 2014 to 2021

BACKGROUND

There has been expanding use of platelet-rich plasma (PRP) in the management of musculoskeletal soft tissue injuries.

PURPOSE

To determine if there are any recent studies that show any clear benefits regarding the use of PRP in the management of soft tissue injuries.

STUDY DESIGN

Systematic review.

METHODS

This review was conducted according to PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. The EMBASE, MEDLINE, PubMed, and Cochrane Bone, Joint and Muscle Group Specialised Register databases were queried for randomized controlled trials comparing PRP with a non-PRP/placebo in participants >18 years of age with musculoskeletal soft tissue injuries. Exclusion criteria were non-soft tissue injuries and research published in journals with an impact factor <3.5. The main outcome measure analyzed across all injury types was the effect of PRP injections on pain and function.

RESULTS

Of the 853 studies initially screened, 32 were included in this review. There were 13 studies that investigated the effects of PRP on the management of rotator cuff injuries; 7 studies that investigated PRP in conjunction with arthroscopy found no significant difference between PRP groups and controls, while 5 of 6 studies that investigated nonsurgical management showed positive results for PRP. Eight studies investigated various tendinopathies; of these, 2 studies demonstrated positive results for PRP in Achilles and gluteal tendinopathy management. Six studies examined PRP in acute soft tissue injuries, with 2 of these reporting significant improvements in recovery time for hamstring injuries and 1 study showing positive results for ankle ligament injuries. Two studies looked at acute rupture of soft tissues and found no benefit to PRP use. Two studies investigated PRP injections for chronic plantar fasciitis, and both reported positive results in pain and function with PRP. Finally, 1 study evaluated the effects of PRP on meniscal injuries and reported significant improvement in the healing rate and a decreased need for surgical repair.

CONCLUSION

Currently, there is no research strongly advocating the use of PRP compared with traditional management strategies (rest, ice, corticosteroid injection, rehabilitation program). No long-term physiological benefits were reported to justify the invasive and costly technique of obtaining, producing, and implementing PRP.

Ultrasound-guided musculoskeletal interventional procedures around the shoulder

Ultrasound is a fast, accessible, reliable, and radiation-free imaging modality routinely used to assess the soft tissues around the shoulder. It enables to identify a wide range of pathological conditions. Furthermore, most ultrasound-guided musculoskeletal interventional procedures around the shoulder produce better results in terms of accuracy and clinical efficacy than those performed in a blinded fashion. Indeed, intra-articular and peri-articular interventional procedures can be easily performed under continuous ultrasound monitoring to ensure the correct position of the needle and to deliver the medication to a specific target. Several technical approaches and medications can be used to treat different causes of painful shoulder. Intra-articular injections are applied to treat acromioclavicular osteoarthritis as well as glenohumeral joint osteoarthritis and adhesive capsulitis. Subacromial-subdeltoid bursitis, either presenting as a primary inflammatory condition or secondary to rotator cuff disorders, can be easily approached using ultrasound guidance to aspirate synovial effusion and to inject medications. Ultrasound-guided percutaneous irrigation is a well-established technique increasingly applied to treat patients with rotator cuff calcific tendinopathy. Also, degenerative rotator cuff tendinopathy can be conservatively treated by image-guided interventions, specifically with needling under ultrasound guidance that can be associated with injections of platelet-rich plasma. Lastly, periarticular peripheral nerve block can be quickly and safely performed under ultrasound guidance, particularly in conditions involving the suprascapular nerve in the setting of pre-operative analgesia or pain treatment in glenohumeral osteoarthritis and adhesive capsulitis. In this article, the most common ultrasound-guided procedures around the shoulder have been reviewed to discuss indications and techniques.