Abstract
Background
The pathophysiology of enthesopathy and tendinopathy is mucoid degeneration, which includes chondroid metaplasia. The chondroid metaplasia can be associated with calcification. Inflammation is typically absent unless calcification triggers a self-limited immune response representing acute calcific tendinitis. It is therefore important to address the hypothesis that calcific deposits within various entheses and tendons throughout the body are an inconsequential epiphenomenon of enthesopathy and tendinopathy and do not merit a distinct diagnosis or specific treatment.
Methods
We searched PubMed, Embase, and Web of Science for studies that address the prevalence of calcium in tendons and entheses with or without symptoms of tendinopathy, specifically excluding likely acute calcific tendinitis, and analyzed 35 studies meeting inclusion and exclusion criteria. Response variables included prevalence of calcification in and enthesis or tendon among people with no symptoms, among people seeking care for symptoms, and in the opposite asymptomatic limb, and the association between calcification and rotator cuff degeneration.
Results
Calcification of tendons and entheses was present on between 2.7 % and 8.6 % of radiographs of the shoulder, elbow, and ankle among people without symptoms and not seeking care, with higher percentages in older populations. Calcification was common among patients with symptoms: 44 % for rotator cuff tendinopathy, 25 % for enthesopathy of the origin of the extensor carpi radialis brevis, and 53 % for medial elbow enthesopathy. Most people with calcification had it bilaterally. Among people with calcification of the rotator cuff on MRI, nearly all of them (96 %) had tendon degeneration.
Conclusions
The collective evidence regarding calcification in tendons and entheses suggests that it is related to mucoid degeneration and is not a separate disease process. Acute calcific tendinitis rapidly runs its course and is treated only to alleviate symptoms. It's not clear that acute calcific tendinitis or rotator cuff tendinopathy with calcification benefit from specific treatment of the calcium deposits.
Level of evidence
Not applicable.
Keywords: Shoulder, Rotator cuff, Calcification, Tendinopathy, Enthesopathy
1. Introduction
Tendinopathy and enthesopathy are among the most common conditions for which people seek upper extremity musculoskeletal specialty care.1 The pathophysiology of enthesopathy and tendinopathy is mucoid degeneration, which includes chondroid metaplasia.2 The chondroid metaplasia can be associated with calcification.3 Inflammation is not present, with or without calcification.3 Calcification associated with enthesopathy and tendinopathy seems to be incidental and unimportant unless the calcium is exposed to the immune system, at which point it can become an inflammatory, intensely painful, acute calcific tendinitis.4 Fortunately, that process resolves completely over a few weeks and the calcium is often absorbed in the process.
The presence of calcium deposits within the rotator cuff tendons is often conceptualized as a unique pathophysiology, a specific source of symptoms, and a target for treatment.5, 6, 7 The calcium may be relevant when it triggers an intensely painful immune response. Otherwise, calcification seems to be an integral aspect of the mucoid degeneration of enthesopathy or tendinopathy. The idea that calcification is a distinct form tendinopathy or enthesopathy may be incorrect and misleading. Specifically, treatments that address the calcification may be unlikely to outperform simulated treatment, meaning that there may be no specific benefit to treatment of the calcification. And after treatment of the calcification, symptoms from the enthesopathy or tendinopathy may persist. It is therefore important to address the hypothesis that calcific deposits within various entheses and tendons throughout the body may be an inconsequential epiphenomenon of enthesopathy and tendinopathy and may not merit a distinct diagnosis or specific treatment.
1.1. Questions
We reviewed original research publications that provide evidence regarding calcification in tendons and entheses and asked: 1) What is the prevalence of calcification in an enthesis or tendon on radiographs in the general population? 2) What is the prevalence of calcium in an enthesis or tendon in people with diagnosed enthesopathy or tendinopathy? 3) Is there is a difference in the prevalence of calcification of an enthesis or tendon between the symptomatic and asymptomatic limbs in people with enthesopathy or tendinopathy? 4) Is there an association between rotator cuff tendon calcification and rotator cuff defects? 5) Is there a relationship between activity and tendon calcification?
2. Method
2.1. Protocol and registration
This systematic review was performed in accordance with guidelines from the Cochrane Collaboration and the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) statement. The protocol was registered with PROSPERO (registration number: CRD42024521070).
2.2. Eligibility criteria
All studies addressing the prevalence of calcium in tendons or entheses with or without symptoms of tendinopathy or enthesopathy were considered for this systematic review. There were no exclusions for comorbidities, illnesses, race, ethnicity, or gender. Case reports, letters to editors, meeting abstracts, reviews, and meta-analyses were excluded. We also excluded studies that were definitely or likely (since the descriptions are often vague and ambiguous) addressing acute calcific tendinitis or combining patients with acute calcific tendinitis and patients with calcification as part of tendinopathy/enthesopathy.8, 9, 10 An example of a study that, based on the descriptions in the paper was likely addressing acute calcific tendinitis, but that did not explicitly make a distinction between acute calcific tendinitis and tendinopathy with calcification is the study by Hackett and colleagues.10 They specifically mentioned incidental, ongoing symptomatic, and extremely symptomatic variations of calcification of the rotator cuff tendons, but did not specify which of these was studied, although they mentioned that people with calcification were more likely to have severe pain, which sounds like acute calcific tendinitis.10 This type of imprecision and ambiguity as one motivation for our analysis.
2.3. Search strategy
We searched PubMed, Embase, and Web of Science for articles up to February 1, 2023. Search terms included (“calcific"[All Fields] OR "calcification"[All Fields] OR "calcification, physiologic"[MeSH Terms] OR (“calcification"[All Fields] AND "physiologic"[All Fields]) OR "physiologic calcification"[All Fields] OR "calcifications"[All Fields] OR "calcinosis"[MeSH Terms] OR "calcinosis"[All Fields] OR "calcification"[All Fields]) AND (“tendinous"[All Fields] OR "tendinopathy"[MeSH Terms] OR "tendinopathy"[All Fields] OR "tendinitis"[All Fields] OR "tendons"[MeSH Terms] OR "tendons"[All Fields] OR "tendinous"[All Fields]).
2.4. Selection process
The search yielded a total of 2174 studies. After elimination of duplicates, non-English language publications, case reports, abstracts, meta-analysis, and reviews, 108 articles were selected for further evaluation. Seventy-three of the 108 studies were excluded by screening the titles and abstracts and full-text review. A total of 36 studies satisfied inclusion and exclusion criteria. One study of lateral elbow enthesopathy included only 10 asymptomatic volunteers and 22 patients with symptoms, and reported only statistical associations without counts and was therefore excluded,11 leaving 35 studies for analysis. The reference sections of included studies were searched to ensure all relevant studies were identified for inclusion.
2.5. Data collection process
Data was extracted by one reviewer and confirmed by the senior author. Relevant data were recorded on a computer spreadsheet. The studies were sorted into the following subcategories: prevalence of calcium in an enthesis or tendon on radiographs in the general population, prevalence of calcium in an enthesis or tendons in people with diagnosed tendinopathy or enthesopathy, difference in the prevalence of calcification of an enthesis or tendon between the symptomatic and asymptomatic limbs in people with enthesopathy or tendinopathy, relationship between calcium deposit morphology and symptoms, and relationship between activity and calcification of the enthesis or tendon.
2.6. Variable
Response variables included calcium rate in enthesis or tendon, involved tendon, relationship between activity and calcification, calcium deposit morphology, preexisting pathology like rotator cuff tendinopathy, impingement syndrome or sub acromial pain syndrome and calcification rate in symptomatic and asymptomatic population. The explanatory variables were population, age, sex, and diagnostic test used (MRI, ultrasound, or radiographs).
2.7. Risk of bias assessment
One reviewer evaluated the quality of included studies using the Methodological Index for Nonrandomized Studies (MINORS) tool,12 which is a validated assessment tool that grades noncomparative studies from 0 to 16 based on eight criteria and comparative studies from 0 to 24 based on 12 categories related to study design, outcomes assessed, and follow-up. Across these domains, each item is scored 0 if not reported, 1 when reported but inadequate, and 2 when reported and adequate, such that higher scores represent better study quality. These ratings were audited and approved by the senior author. The score varied between 10 and 19 for non-comparative studies, indicating moderate to low risk of bias, and 16 and 24 for comparative studies, indicating low risk of bias.
3. Results
3.1. What is the prevalence of calcification in an enthesis or tendon in the general population?
In 4 studies of 7223 asymptomatic people representative of the general population, the overall prevalence of calcification in the rotator cuff tendons was 8.6 % with the lowest prevalence of 2.7 % in a population under 40 years of age.13, 14, 15, 16 In 2 population-based studies of the entheses of the origin of the extensor carpi radialis brevis in 28763 asymptomatic people the prevalence of calcification was 3 %.17,18 And in one study of the flexor pronator origin at the medial epicondyle in 111 asymptomatic people the prevalence of calcification on radiographs was 5 %.19
In one study of 52 asymptomatic young adults (mean age 22 years) with moderate or greater activity level 4 % (2 of 52) had ultrasound evidence of Achilles tendinopathy, none with calcification.20 Another study of 51 young (mean age 27 years), asymptomatic volunteers with moderate or high activity levels identified Achilles tendinopathy in 16 % (16 of 102), 56 % (9 of 16) with calcification.21
3.2. What is the prevalence of calcium in tendons or entheses in people with diagnosed tendinopathy or enthesopathy?
Among 870 patients diagnosed with rotator cuff tendinopathy 44 % (383) had calcification.5,14,22,23 Rotator cuff tendon calcification was noted in 8 % (57 of 734) of patients (mean age 53) who had radiographs for shoulder trauma in the emergency department and 43 % (206 of 485) patients referred to a shoulder specialist for care of rotator cuff tendinopathy (mean age 52 years).14 People with symptoms from rotator cuff tendinopathy had larger calcifications (mean 1.2 cm vs. 0.42 cm).14
Among 3 studies including 587 patients diagnosed with enthesopathy of the origin of the extensor carpi radialis brevis (eECRB; lateral epicondylitis), the prevalence of calcification in the origin of the ERCB was 25 % (143 of 587). Symptoms and signs did not differ between patients with and without calcifications and between larger or smaller calcifications.24, 25, 26 A study of 110 patients with eECRB reported a 36 % (38 of 110) prevalence of calcification including 18 % (20 of 110) described as enthesophytes and 16 % (18 of 110) soft tissue calcifications.27 Calcification was associated with prior steroid injection and number of steroid injections.27
In a study comparing 29 people with eECRB to 32 age-, sex-, and dominance-matched pain-free controls, calcification was equally common in symptomatic (5 of 29) and asymptomatic (6 of 32) elbows.28
In one study of 222 elbows of people with medial elbow enthesopathy (MEE), 53 % (118 of 222 elbows) had radiographic calcification and calcification was associated with greater pain intensity, more steroid injections, and concomitant ulnar neuropathy.29 In addition, older age was strongly associated with calcification at more than one site (insertion site of the common flexor tendon, pronator teres and the medial collateral ligament).29 In another study of MRI evaluation of 83 patients with MEE the MRI findings included common flexor tendon origin signal changes (66 %), medial collateral ligament signal changes (30 %), calcification (27 %), bony changes (such as bone marrow edema, cysts, and cortical irregularity of the medial epicondyle (18 %), and ulnar nerve signal changes (40 %) 30In a study of MRIs of 83 patients with MEE, findings included common flexor tendon origin signal changes (66 %), medial collateral ligament signal changes (30 %), calcification (27 %), bony changes (such as bone marrow edema, cysts, and cortical irregularity of the medial epicondyle (18 %), and ulnar nerve signal changes (40 %)30
3.3. Is there is a difference in calcification rate between the symptomatic and asymptomatic limbs in people with enthesopathy or tendinopathy?
Among 115 patients with unilateral rotator cuff tendinopathy symptoms (mean age 45 years), ultrasound of both shoulders identified frequent bursitis (90 % symptomatic, 74 % asymptomatic), tendinopathy (29 % symptomatic, 12 % asymptomatic), and calcification (28 % symptomatic; 21 % asymptomatic). Twenty-one percent (12 of 57) of the calcifications, and 20 % (10 of 50) of the tendinopathies were bilateral.31
In a study of ultrasonography of both shoulders of 302 volunteers, 18 % (103 of 604) of shoulders had calcification in the rotator cuff tendons, including 33 % (34 of 95) of the shoulders with symptoms and 14 % (69 of 509) of asymptomatic shoulders.32
3.4. What is the association of calcification with rotator cuff defects?
In a study that compared 102 people seeking care for shoulder pain that had rotator cuff tendon calcification on radiographs compared to 28 age- and sex-matched patients with similar shoulder symptoms and no radiographic calcifications, MRI identified rotator cuff tendon degeneration in 96 % (97 of 102) of shoulders with tendon calcification (92 with tendinopathy alone, 5 with tendinopathy and thinning (“partial tearing”), and 1 with a full thickness defect) and 93 % (26 of 28) of shoulders without calcification (21 tendinopathy alone, 5 thinning).5
In a study of 239 patients with calcification in the rotator cuff tendons on radiographs and MRI, among the 39 % (93 of 239) who were unsatisfied with nonoperative treatment and accepted an offer of surgery an average of 4.4 months after initial presentation, 83 % (77 of 93) of them also had closure of a rotator cuff defect.33 In a cohort of 318 shoulders with tendon calcification on MRI, 56 % (177 of 318) had a rotator cuff defect (93 % thinning [”partial”, 164 of 177] and 7 % full thickness [13 of 177]).34 Calcification morphology (cloudy with soft contour) was associated with thinning or complete defect, but calcification size and location were not.34 Among 82 patients with shoulder pain and calcification in the rotator cuff tendons on radiographs, 28 % (23 of 82) had evidence of a rotator cuff defect on arthrogram (17 full thickness and 6 partial thickness).35 In another study of 81 patients with shoulder pain and calcification of the rotator cuff tendons that underwent arthrography, 27 % (22 of 81) had thinning or a full thickness defect of the rotator cuff tendons, and more extensive calcification was associated with greater thinning of the tendon.36
In study of 506 Korean patients (mean age, 55 years) with shoulder pain and radiographic tendon calcification, the mean size of calcification was 11 mm and 19 % (98) were bilateral. On evaluation with ultrasound or MRI in 383 of 506 patients (76 %), 11 % (44 of 383) had thinning of the rotator cuff (“partial thickness”) and 4 % (15 of 383) had a full thickness defect. Patients with rotator cuff thinning or defect were somewhat older: mean 58 vs 55 years of age.37
Among 613 patients with shoulder pain who had diagnostic ultrasonography, 9.5 % (58 of 613) had calcification of the rotator cuff tendons. In a comparison of 50 shoulder ultrasound randomly selected from the 58 patients with calcific deposits (mean age, 65 years) and 50 randomly selected from 555 patients age (grouped by decade) and gender-matched without calcification (mean age, 61 years), rotator cuff tendon defects were diagnosed in 22 % (11 of 50) with tendon calcification (12 %, 6 of 50, full-thickness) and 38 % (19 of 50) without calcification (32 %, 16 of 50 full-thickness).38
3.5. Is there a relationship between activity and calcification?
In an ultrasonographic evaluation of rotator cuff tendons of both shoulders among 60 subjects, including 20 master's swimmers with shoulder pain (mean age: 51 years), 20 asymptomatic master's swimmers (mean age: 52 years), and 20 sex- and age-matched controls (mean age: 51 years) who were not engaged in regular exercise or sports activities at enrolment, the prevalence of calcification was similar between swimmers with and without shoulder symptoms but significantly higher than shoulders of inactive people.39
Among 150 competition-level tennis players (mean age, 55 years) evaluated with ultrasound, subscapularis tendon calcifications were identified in 23 dominant and 12 contralateral shoulders.40
On sonographic evaluation of the Achilles and patellar tendons of 79 asymptomatic professional ballet dancers (mean age: 27 years), calcifications were noted in 16 of 178 (10 %) patellar tendons and in 3 of 178 (2 %) Achilles tendons. Over a period of 24 months, 14 of 16 patellar tendons and 2 of 3 Achilles tendons remained asymptomatic.41
In ultrasound scans of bilateral medial elbows of 41 college pitchers, enthesopathy was reported in 24 % (10 of 41)) on the throwing side and in 7 % (3 of 41) on the non-throwing side elbows. Calcification was reported in 60 % (6 of 10) of the throwing side elbows and 67 % (2 of 3) of the non-throwing side elbows.42
4. Discussion
The pathophysiology of tendinopathy and enthesopathy is mucoid degeneration.2,43 One aspect of mucoid degeneration is chondroid metaplasia of fibroblasts.2 Deposition of calcium in tendons commonly accompanies chondroid metaplasia. The calcification in the tendon or enthesis is often conceptualized as a distinct, separately treatable source of pain rather than an integral feature of tendinopathy and enthesopathy.6,7 We systematically reviewed evidence regarding calcification in tendons and entheses, including associated pathophysiology and symptoms. We found that the prevalence of calcification in the general population corresponds with the prevalence of tendinopathy and enthesopathy, that about half of people with diagnosed tendinopathy or enthesopathy have calcification on radiographs, that imaging of calcification corresponds with imaging of tendinopathy, that calcification is about twice as common in the symptomatic compared to the asymptomatic shoulders, that people with symptoms tend to have larger calcifications, and that symptoms and signs do not differ between patients with and without calcifications and between larger or smaller calcifications. Our concern is that calcification is often considered a distinct pathology with distinct treatment whereas this evidence points to calcification as an integral aspect of tendinopathy and enthesopathy with no benefit from specific invasive treatment.
4.1. Limitations
The primary limitation of this systematic review is that few studies made a clear distinction between acute calcific tendonitis versus calcification as a part of more typical tendinopathy or enthesopathy. Acute calcific tendinitis is a brief, transient inflammatory response to crystals of calcification that are exposed that the immune system may regard as foreign material. It is treated with non-specific symptom alleviation and represents a separate condition. Another limitation is that many publications consider calcification of a part of tendon or enthesis a distinct pathological finding meriting specific treatment. We stand to learn from experiments that consider the possibility that the calcification may be an integral part of the mucoid degeneration and chondroid metaplasia. Another limitation is the heterogeneity of inclusion criteria such as type and level of age, symptoms, activity level, and concomitant illness.
4.2. What is the prevalence of calcification in an enthesis or tendon in the general population?
The observation that calcification of tendons and entheses is common among people not seeking care emphasizes that calcification is common, likely an aspect the aging of human collagenous structures (senescence) and disconnected from symptoms.
4.3. What is the prevalence of calcium in tendons or entheses in people with diagnosed tendinopathy or enthesopathy?
The observation that between 3 and 5 in 10 people seeking care for symptoms from tendinopathy or enthesopathy has calcification on radiographs supports the conception of calcification as an integral part of these pathophysiological processes. While one of the most prominent voices on calcification has argued that calcification is process distinct from mucoid degeneration,44 that view seems worth rethinking.44 It seems plausible that fibroblasts that have transformed into cells with characteristics of chondrocytes might also produce cartilage, in particular as part of cellular senescence.2,45,46
4.4. Is there is a difference in calcification rate between the symptomatic and asymptomatic limbs in people with enthesopathy or tendinopathy?
The observation that evaluation of asymptomatic shoulders among people with unilateral symptoms of rotator cuff tendinopathy often identifies calcification is in line with the prevalence of asymptomatic tendinopathy in contralateral shoulders.47,48 The occurrence of calcification might be associated with the duration, extent, and severity of the tendinopathy.
4.5. What is the association of calcification with rotator cuff defects?
The observation that rotator cuff tendon calcification corresponds with rotator cuff tendinopathy and degenerative rotator cuff defects is also supportive of the conceptualization of calcification as an integral aspect of rotator cuff senescence.
4.6. Is there a relationship between activity and calcification?
The finding that athletes have calcification coincident with tendinopathy and enthesopathy further supports the concept that calcification is an expected aspect of these pathophysiologies.
5. Conclusions
The collective evidence regarding calcification in tendons and entheses suggests that it is related to mucoid degeneration and is not a separate disease process. Acute calcific tendinitis rapidly runs its course and is treated only to alleviate symptoms. It's not clear that acute calcific tendinitis or rotator cuff tendinopathy with calcification benefit from specific treatment of the calcium deposits. Pending evidence that there is a benefit to treating calcification of tendinopathy or enthesopathy differently than these pathophysiologies absent calcification, we suggest the calcification not be considered a distinct disease.
CRediT authorship contribution statement
Amin Razi: Methodology, Formal analysis, Investigation, Resources, Writing – original draft. David Ring: Conceptualization, Methodology, Validation, Resources, Writing – review & editing, Supervision, Project administration.
Funding
This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.
Footnotes
This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.
References
- 1.Crijns T.J., Ring D., Valencia V. Factors associated with the cost of care for the most common atraumatic painful upper extremity conditions. J Hand Surg Am. 2019;44(11):989.e1–989.e18. doi: 10.1016/J.JHSA.2019.01.001. [DOI] [PubMed] [Google Scholar]
- 2.Bruni D.F., Pierson S.R., Sarwar F., Ring D., Ramtin S. Are the pathologic features of enthesopathy, tendinopathy, and labral and articular disc disease related to mucoid degeneration? A systematic review. Clin Orthop Relat Res. 2023;481(4):641–650. doi: 10.1097/CORR.0000000000002499. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 3.Kiriti S. Calcifying tendinitis its pathogenetic mechanism and a rationale for its treatment. Int Orthop. 1978;2:187–193. [Google Scholar]
- 4.Sansone V., Maiorano E., Galluzzo A., Pascale V. Calcific tendinopathy of the shoulder: clinical perspectives into the mechanisms, pathogenesis, and treatment. Orthop Res Rev. 2018;10:63. doi: 10.2147/ORR.S138225. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 5.Maier M., Stäbler A., Schmitz C., et al. On the impact of calcified deposits within the rotator cuff tendons in shoulders of patients with shoulder pain and dysfunction. Arch Orthop Trauma Surg. 2001;121(7):371–378. doi: 10.1007/S004020000255. [DOI] [PubMed] [Google Scholar]
- 6.Vassalou E.E., Klontzas M.E., Plagou A.P., Karantanas A.H. Ultrasound-guided percutaneous irrigation of calcific tendinopathy: redefining predictors of treatment outcome. Eur Radiol. 2021;31(4):2634–2643. doi: 10.1007/S00330-020-07334-2. [DOI] [PubMed] [Google Scholar]
- 7.Seil R., Litzenburger H., Kohn D., Rupp S. Arthroscopic treatment of chronically painful calcifying tendinitis of the supraspinatus tendon. Arthroscopy. 2006;22(5):521–527. doi: 10.1016/J.ARTHRO.2006.01.012. [DOI] [PubMed] [Google Scholar]
- 8.Chiou H.J., Chou Y.H., Wu J.J., Hsu C.C., Huang D.Y., Chang C.Y. Evaluation of calcific tendonitis of the rotator cuff: role of color Doppler ultrasonography. J Ultrasound Med. 2002;21(3):289–295. doi: 10.7863/JUM.2002.21.3.289. [DOI] [PubMed] [Google Scholar]
- 9.Le Goff B., Berthelot J.M., Guillot P., Glémarec J., Maugars Y. Assessment of calcific tendonitis of rotator cuff by ultrasonography: comparison between symptomatic and asymptomatic shoulders. Joint Bone Spine. 2010;77(3):258–263. doi: 10.1016/J.JBSPIN.2010.01.012. [DOI] [PubMed] [Google Scholar]
- 10.Hackett L., Millar N.L., Lam P., Murrell G.A.C. Are the symptoms of calcific tendinitis due to neoinnervation and/or neovascularization? J Bone Joint Surg Am. 2016;98(3):186–192. doi: 10.2106/JBJS.O.00417. [DOI] [PubMed] [Google Scholar]
- 11.Levin D., Nazarian L.N., Miller T.T., et al. Lateral epicondylitis of the elbow: US findings. Radiology. 2005;237(1):230–234. doi: 10.1148/RADIOL.2371040784. [DOI] [PubMed] [Google Scholar]
- 12.Slim K., Nini E., Forestier D., Kwiatkowski F., Panis Y., Chipponi J. Methodological index for non-randomized studies (MINORS): development and validation of a new instrument. ANZ J Surg. 2003;73(9):712–716. doi: 10.1046/J.1445-2197.2003.02748.X. [DOI] [PubMed] [Google Scholar]
- 13.Bosworth B.M. Calcium deposits in the shoulder and subacromial bursitis: a survey of 12,122 shoulders. J Am Med Assoc. 1941;116(22):2477–2482. doi: 10.1001/JAMA.1941.02820220019004. [DOI] [Google Scholar]
- 14.Louwerens J.K.G., Sierevelt I.N., van Hove R.P., van den Bekerom M.P.J., van Noort A. Prevalence of calcific deposits within the rotator cuff tendons in adults with and without subacromial pain syndrome: clinical and radiologic analysis of 1219 patients. J Shoulder Elbow Surg. 2015;24(10):1588–1593. doi: 10.1016/J.JSE.2015.02.024. [DOI] [PubMed] [Google Scholar]
- 15.Meroni R., Piscitelli D., Valerio S., et al. Ultrasonography of the shoulder: asymptomatic findings from working-age women in the general population. J Phys Ther Sci. 2017;29(7):1219–1223. doi: 10.1589/JPTS.29.1219. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 16.Welfling J., Kahn M.F., Desroy M., Paolaggi J.B., de Sèze S. [Calcifications of the shoulder. II. The disease of multiple tendinous calcifications] Rev Rhum Mal Osteoartic. 1965;32(6):325–334. https://europepmc.org/article/MED/5843171 [PubMed] [Google Scholar]
- 17.Ustuner E., Toprak U., Baskan B., Oztuna D. Sonographic examination of the common extensor tendon of the forearm at three different locations in the normal asymptomatic population. Surg Radiol Anat. 2013;35(7):547–552. doi: 10.1007/S00276-013-1084-6. [DOI] [PubMed] [Google Scholar]
- 18.Tarabochia M., Janssen S.J., Ogink P.T., Ring D., Chen N.C. The prevalence of calcifications at the origin of the extensor carpi radialis brevis increases with age. Arch Bone Jt Surg. 2020;8(1):21–26. doi: 10.22038/ABJS.2019.31558.1823. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 19.Parlak S., Beşler M.S., Özer H., Başkan B., Toprak U. A comprehensive ultrasonographic investigation of the common flexor tendon and medial epicondyle in asymptomatic individuals. Med Ultrason. 2019;21(3):273–278. doi: 10.11152/MU-1926. [DOI] [PubMed] [Google Scholar]
- 20.Joseph M.F., Anderson J.M., Trojian T.H., Crowley J. Incidence of morphologic changes in asymptomatic Achilles tendons in an active young adult population. J Sport Rehabil. 2012;21(3):249–252. doi: 10.1123/JSR.21.3.249. [DOI] [PubMed] [Google Scholar]
- 21.Noback P.C., Freibott C.E., Tantigate D., et al. vol. 39. 2018. pp. 1205–1209. (Prevalence of Asymptomatic Achilles Tendinosis). 10. [DOI] [PubMed] [Google Scholar]
- 22.Eliason A., Harringe M., Engström B., Sunding K., Werner S. Bilateral ultrasound findings in patients with unilateral subacromial pain syndrome. Physiother Theory Pract. 2022;38(13):2568–2579. doi: 10.1080/09593985.2021.1962462. [DOI] [PubMed] [Google Scholar]
- 23.Clavert P., Sirveaux F. [Shoulder calcifying tendinitis] Rev Chir Orthop Reparatrice Appar Mot. 2008;94(8 Suppl):336–355. doi: 10.1016/J.RCO.2008.09.010. [DOI] [PubMed] [Google Scholar]
- 24.Connell D., Burke F., Coombes P., et al. Sonographic examination of lateral epicondylitis. AJR Am J Roentgenol. 2001;176(3):777–782. doi: 10.2214/AJR.176.3.1760777. [DOI] [PubMed] [Google Scholar]
- 25.Shillito M., Soong M., Martin N. Radiographic and clinical analysis of lateral epicondylitis. J Hand Surg Am. 2017;42(6):436–442. doi: 10.1016/J.JHSA.2017.03.016. [DOI] [PubMed] [Google Scholar]
- 26.Pomerance J. Radiographic analysis of lateral epicondylitis. J Shoulder Elbow Surg. 2002;11(2):156–157. doi: 10.1067/mpn.2002.121147. [DOI] [PubMed] [Google Scholar]
- 27.Park H Bin, Kam M., Gwark J.Y. Association of steroid injection with soft-tissue calcification in lateral epicondylitis. J Shoulder Elbow Surg. 2019;28(2):304–309. doi: 10.1016/J.JSE.2018.10.009. [DOI] [PubMed] [Google Scholar]
- 28.Heales L.J., Hodges P.W., Vicenzino B. An investigation of the asymptomatic limb in unilateral lateral epicondylalgia. Med Sci Sports Exerc. 2015;47(11):2268–2272. doi: 10.1249/MSS.0000000000000681. [DOI] [PubMed] [Google Scholar]
- 29.Kang K.B., Cheon S.H., Lee H.D. Radiologic evaluation and clinical effect of calcification in medial epicondylitis. J Shoulder Elbow Surg. 2022;31(2):375–381. doi: 10.1016/J.JSE.2021.08.031. [DOI] [PubMed] [Google Scholar]
- 30.Bae K.J., Park C., Ahn J.M., Kang Y., Gong H.S. Magnetic resonance imaging evaluation of patients with clinically diagnosed medial Epicondylitis. Skeletal Radiol. 2021;50(8):1629–1636. doi: 10.1007/S00256-021-03720-Z. [DOI] [PubMed] [Google Scholar]
- 31.Eliason A., Harringe M., Engström B., Sunding K., Werner S. Bilateral ultrasound findings in patients with unilateral subacromial pain syndrome. Physiother Theory Pract. 2022;38(13):2568–2579. doi: 10.1080/09593985.2021.1962462. [DOI] [PubMed] [Google Scholar]
- 32.Sansone V., Consonni O., Maiorano E., Meroni R., Goddi A. Calcific tendinopathy of the rotator cuff: the correlation between pain and imaging features in symptomatic and asymptomatic female shoulders. Skeletal Radiol. 2016;45(1):49–55. doi: 10.1007/S00256-015-2240-3. [DOI] [PubMed] [Google Scholar]
- 33.Drummond Junior M., Ayinon C., Rodosky M., Vyas D., Lesniak B., Lin A. Predictive factors for failure of conservative management in the treatment of calcific tendinitis of the shoulder. JSES Int. 2021;5(3):469–473. doi: 10.1016/J.JSEINT.2021.01.013. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 34.Brinkman J.C., Zaw T.M., Fox M.G., et al. Calcific tendonitis of the shoulder: protector or predictor of cuff pathology? A magnetic resonance imaging–based study. Arthrosc J Arthrosc Relat Surg. 2020;36(4):983–990. doi: 10.1016/J.ARTHRO.2019.11.127. [DOI] [PubMed] [Google Scholar]
- 35.Hsu H.C., Wu J.J., Jim Y.F., Chang C.Y., Lo W.H., Yang D.J. Calcific tendinitis and rotator cuff tearing: a clinical and radiographic study. J Shoulder Elbow Surg. 1994;3(3):159–164. doi: 10.1016/S1058-2746(09)80095-5. [DOI] [PubMed] [Google Scholar]
- 36.Jim Y.F., Hsu H.C., Chang C.Y., Wu J.J., Chang T. Coexistence of calcific tendinitis and rotator cuff tear: an arthrographic study. Skeletal Radiol. 1993;22(3):183–185. doi: 10.1007/BF00206150. [DOI] [PubMed] [Google Scholar]
- 37.Yoo Y.S., Park J.Y., Kim M sun, et al. Calcific tendinitis of the shoulder in the Korean population: demographics and its relation with coexisting rotator cuff tear. Clin Shoulder Elb. 2021;24(1):21. doi: 10.5397/CISE.2020.00010. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 38.Laucis N.C., Rosen K.A., Thodge A., Leschied J.R., Klochko C.L., Soliman S.B. Sonographic evaluation of the association between calcific tendinopathy and rotator cuff tear: a case-controlled comparison. Clin Rheumatol. 2021;40(7):2897–2905. doi: 10.1007/S10067-021-05597-8. [DOI] [PubMed] [Google Scholar]
- 39.Suzuki Y., Maeda N., Sasadai J., Kaneda K., Shirakawa T., Urabe Y. 2020. Medicina Ultrasonographic Evaluation of the Shoulders and its Associations with Shoulder Pain, Age, and Swim Training in Masters Swimmers. Published online. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 40.Brasseur J.L., Lucidarme O., Tardieu M., et al. Ultrasonographic rotator-cuff changes in veteran tennis players: the effect of hand dominance and comparison with clinical findings. Eur Radiol. 2004;14(5):857–864. doi: 10.1007/S00330-003-2116-0. [DOI] [PubMed] [Google Scholar]
- 41.Comin J., Cook J.L., Malliaras P., et al. The prevalence and clinical significance of sonographic tendon abnormalities in asymptomatic ballet dancers: a 24-month longitudinal study. Br J Sports Med. 2013;47(2):89–92. doi: 10.1136/BJSPORTS-2012-091303. [DOI] [PubMed] [Google Scholar]
- 42.Lobb N.J., Lu Z., Long E., Chow K., Michener L.A. Sonographic morphological and qualitative deficits in the elbow ulnar collateral ligament and ulnohumeral joint in throwing arms of asymptomatic collegiate baseball pitchers. Skeletal Radiol. 2023;52(1):31–37. doi: 10.1007/S00256-022-04116-3. [DOI] [PubMed] [Google Scholar]
- 43.Khan K.M., Cook J.L., Bonar F., Harcourt P., Åstrom M. Histopathology of common tendinopathies. Update and implications for clinical management. Sports Med. 1999;27(6):393–408. doi: 10.2165/00007256-199927060-00004. [DOI] [PubMed] [Google Scholar]
- 44.Uhthoff H.K., Sarkar K., Maynard J.A. Calcifying tendinitis: a new concept of its pathogenesis. Clin Orthop Relat Res. 1976;118(118):164–168. https://europepmc.org/article/MED/954272 [PubMed] [Google Scholar]
- 45.Meyer F., Dittmann A., Kornak U., et al. Chondrocytes from osteoarthritic and chondrocalcinosis cartilage represent different phenotypes. Front Cell Dev Biol. 2021;9 doi: 10.3389/FCELL.2021.622287. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 46.Hashimoto S., Ochs R.L., Rosen F., et al. Chondrocyte-derived apoptotic bodies and calcification of articular cartilage. Proc Natl Acad Sci USA. 1998;95(6):3094–3099. doi: 10.1073/PNAS.95.6.3094/ASSET/2F2D7CFC-0F77-42A9-8360-03FEC686D233/ASSETS/GRAPHIC/PQ0584399004.JPEG. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 47.Yamaguchi K., Ditsios K., Middleton W.D., Hildebolt C.F., Galatz L.M., Teefey S.A. The demographic and morphological features of rotator cuff disease. A comparison of asymptomatic and symptomatic shoulders. J Bone Joint Surg Am. 2006;88(8):1699–1704. doi: 10.2106/JBJS.E.00835. [DOI] [PubMed] [Google Scholar]
- 48.Liu T.C., Leung N., Edwards L., Ring D., Bernacki E., Tonn M.D. Patients older than 40 Years with unilateral occupational claims for new shoulder and knee symptoms have bilateral MRI changes. Clin Orthop Relat Res. 2017;475(10):2360–2365. doi: 10.1007/S11999-017-5401-Y. [DOI] [PMC free article] [PubMed] [Google Scholar]