The assessment of Achilles tendon size in primary hypercholesterolaemia by computed tomography

Quantitative evaluation of the Achilles tendon and supraspinatus tendon in end-stage kidney disease patients: A potential tool for predicting spontaneous tendon rupture

Many cases of spontaneous tendon rupture in end-stage kidney disease (ESKD) patients have been reported worldwide. Quantitative assessment of tendon has become an important way to improve the prognosis of patients. In the recruited healthy volunteers and ESKD patients, the thickness and shear wave velocity (SWV) of supraspinatus tendons and Achilles tendons were measured and compared among groups. Potential factors related to the tendon SWV of ESKD patients were screened in multiple linear regression. There was no significant difference in the tendon thickness and supraspinatus tendon SWV among groups. SWV of Achilles tendons in long-term dialysis ESKD patients were significantly lower than those in healthy volunteers (5.1 vs. 5.6 m/s, p < 0.01). Ca²⁺ , creatinine, body mass index, and genders are the significant factors related to the tendon SWV. Shear wave elastography can be used as a potential tool for predicting spontaneous tendon rupture in ESKD patients.

Cross-Sectional Area Measurement Techniques of Soft Tissue: A Literature Review

Evaluation of the biomechanical properties of soft tissues by measuring the stress-strain relationships has been the focus of numerous investigations. The accuracy of stress depends, in part, upon the determination of the cross-sectional area (CSA). However, the complex geometry and pliability of soft tissues, especially ligaments and tendons, make it difficult to obtain accurate CSA, and the development of CSA measurement methods of soft tissues continues. Early attempts to determine the CSA of soft tissues include gravimetric method, geometric approximation technique, area micrometer method, and microtomy technique. Since 1990, a series of new methods have emerged, including medical imaging techniques (e.g. magnetic resonance imaging (MRI), computed tomography (CT), and ultrasound imaging (USI)), laser techniques (e.g. the laser micrometer method, the linear laser scanner (LLS) technique, and the laser reflection system (LRS) method), molding techniques, and three-dimensional (3D) scanning techniques.

A review of methods to measure tendon dimensions

Tendons are soft tissues of the musculoskeletal system that are designed to facilitate joint movement. Tendons exhibit a wide range of mechanical properties matched to their functions and, as a result, have been of interest to researchers for many decades. Dimensions are an important aspect of tendon properties.

Change in the dimensions of tissues is often seen as a sign of injury and degeneration, as it may suggest inflammation or general disorder of the tissue. Dimensions are also important for determining the mechanical properties and behaviours of materials, particularly the stress, strain, and elastic modulus. This makes the dimensions significant in the context of a mechanical study of degenerated tendons. Additionally, tendon dimensions are useful in planning harvesting for tendon transfer and joint reconstruction purposes.

Historically, many methods have been used in an attempt to accurately measure the dimensions of soft tissue, since improper measurement can lead to large errors in the calculated properties. These methods can be categorised as destructive (by approximation), contact, and non-contact and can be considered in terms of in vivo and ex vivo.

Ultrasonography of the Achilles Tendon in Hypercholesterolemia

The ultrasonographic (US) appearance of Achilles tendon was examined in 34 patients with hypercholesterolemia (10 with familial (FH), and 24 with secondary hypercholesterolemia (SH)), and in 22 patients with normal tendons. US findings were compared with clinical, laboratory, and radiologic results. In patients with FH, typical xanthomas in the form of hyperechoic tendinal tumors were found in only 15% while various forms of inhomogeneity of tendon structure without xanthoma formation were found in 75%. The high rate of tendon inhomogeneity may be due to the concomitant occurrence of both xanthomas and degeneration of tendon fibers. Physical examination revealed abnormalities in 60% of these patients. At CT of the tendons, abnormalities were found in 65% of the FH patients and in 40%, abnormalities were shown by plain radiography. In SH, the results did not differ significantly from normal controls. In our opinion US should be used to prove or rule out Achilles tendon abnormalities in patients with FH for prophylaxis and treatment of tendinitis and tendon rupture.

Is higher serum cholesterol associated with altered tendon structure or tendon pain? A systematic review

Background

Tendon pain occurs in individuals with extreme cholesterol levels (familial hypercholesterolaemia). It is unclear whether the association with tendon pain is strong with less extreme elevations of cholesterol.

Objective

To determine whether lipid levels are associated with abnormal tendon structure or the presence of tendon pain.

Methods

We conducted a systematic review and meta-analysis. Relevant articles were found through an electronic search of 6 medical databases—MEDLINE, Cochrane, AMED, EMBASE, Web of Science and Scopus. We included all case–control or cross-sectional studies with data describing (1) lipid levels or use of lipid-lowering drugs and (2) tendon structure or tendon pain.

Results

17 studies (2612 participants) were eligible for inclusion in the review. People with altered tendon structure or tendon pain had significantly higher total cholesterol, low-density lipoprotein cholesterol and triglycerides, as well as lower high-density lipoprotein cholesterol; with mean difference values of 0.66, 1.00, 0.33, and −0.19 mmol/L, respectively.

Conclusions

The results of this review indicate that a relationship exists between an individual’s lipid profile and tendon health. However, further longitudinal studies are required to determine whether a cause and effect relationship exists between tendon structure and lipid levels. This could lead to advancement in the understanding of the pathoaetiology and thus treatment of tendinopathy.

Familial hypercholesterolaemia commonly presents with Achilles tenosynovitis

BACKGROUND

Patients with heterozygous familial hypercholesterolaemia (HeFH) develop tendon xanthomata (TX), most commonly in their Achilles tendons. Even before tendons are chronically enlarged, tenosynovitis may occur and medical advice be sought. Untreated HeFH carries a high risk of premature coronary heart disease, which can be ameliorated by early diagnosis.

OBJECTIVE

To determine the prevalence of episodes of Achilles tendon pain in HeFH before its diagnosis.

METHODS

Patients with definite HeFH (Simon Broome criteria) attending a lipid clinic were identified. They completed a questionnaire asking about symptoms relating to their Achilles tendons. Unaffected spouses or cohabiting partners served as controls.

RESULTS

133 patients (47% men) and 87 controls (51% men) participated. TX had been recognised by the referring physicians in <5% of cases. However, 62 (46.6% (95% confidence interval (CI) 38.1 to 55.1)) patients had experienced one or more episodes of pain in one or both Achilles tendons lasting >3 days, whereas only 6 (6.9% (1.6 to 12.2)) controls had done so (difference p<0.001; likelihood ratio 6.75). Typically, in the patients with HeFH the pain lasted 4 days (median). It was described as severe or very severe in 24/62 (38.7% (30.4 to 47.0)) patients with HeFH, but never more than moderate in controls. 35 (26.3% (18.8 to 33.8)) patients with HeFH had consulted a doctor about Achilles tendon pain, but in no case had this led to a diagnosis of HeFH. None of the controls had consulted a doctor.

CONCLUSIONS

Measurement of serum cholesterol in patients presenting with painful Achilles tendon could lead to early diagnosis of HeFH.

Pathogenesis, detection and treatment of Achilles tendon xanthomas

Tendon xanthomatosis often accompanies familial hypercholesterolaemia, but it can also occur in other pathologic states. Achilles tendons are the most common sites of tendon xanthomas. Low-density lipoprotein (LDL) derived from the circulation accumulates into tendons. The next steps leading to the formation of Achilles tendon xanthomas (ATX) are the transformation of LDL into oxidized LDL (oxLDL) and the active uptake of oxLDL by macrophages within the tendons. Although physical examination may reveal Achilles tendon xanthomas (ATX), there are several imaging methods for their detection. It is worth mentioning that ultrasonography is the method of choice in everyday clinical practice. Although several treatments for Achilles tendon xanthomas (ATX) have been proposed (LDL apheresis, statins, etc.), they target mostly in the treatment of the basic metabolic disorder of lipid metabolism, which is the main cause of these lesions. In this review we describe the formation, detection, differential diagnosis and treatment of ATX as well as the relationship between tendon xanthomas and atheroma.

Xanthomas of the Achilles tendon: report of a bilateral case and review of the literature

We report a case of bilateral Achilles tendon xanthoma as the first clinical manifestation of familial hypercholesterolemia. We review the literature and stress the need for orthopaedic surgeons to be familiar with this disease. An early diagnosis of this metabolic disorder is important to institute medical therapy and to alter the course of the disease before the onset of coronary artery disease.

Evaluation of the aortic root by MRI: insights from patients with homozygous familial hypercholesterolemia

BACKGROUND

In homozygous familial hypercholesterolemia (HFH), the aortic root is prone to develop atherosclerotic plaque at an early age. However, the aortic wall and plaque have not yet been assessed in this condition by MRI. We evaluated the aortic root by use of MRI in 17 HFH patients and 12 normal control subjects in a prospective, blinded, controlled study.

METHODS AND RESULTS

Morphological assessment of the aortic root was done with spin-echo and gradient-echo MRI scanning. Comparisons were made with a number of measures of disease severity, including cholesterol-year score, calcium score on electron-beam CT (EBCT), and size of Achilles tendon xanthomas. Atherosclerotic plaque, visible on fat-suppressed images but never on water-suppressed images, was present in 9 HFH patients (53%). Supravalvular aortic stenosis was present in 7 patients with HFH (41%). Maximum supravalvular aortic wall thickness was significantly greater and OD and lumen cross-sectional area (CSA) were smaller in patients than in control subjects (P=0.006, 0.0005, and 0.06, respectively). Maximum wall thickness was associated with a greater calcium score on electron-beam CT (P=0.02). Although the cumulative exposure of the aortic root to cholesterol (the cholesterol-year score) was significantly correlated with the Achilles tendon CSA and vascular calcification, this score did not correlate with the wall thickness or aortic CSA.

CONCLUSIONS

This study not only demonstrates the utility of MRI for detecting and characterizing aortic root atherosclerotic plaque and supravalvular aortic stenosis in HFH patients but also suggests that the LDL receptor plays a direct or indirect role in aortic mural development and vascular growth.

Imaging of tendons--adaptation, degeneration, rupture

Tendon imaging is mainly performed with ultrasonography (US) and magnetic resonance imaging (MRI) and has been improved within the last years because of technical advancements and a better understanding of tendon pathology. Several concepts concerning the etiology and the course of tendon diseases have influenced image interpretation and vice versa. Adaptive mechanisms within the tendon tissue against stress can be observed mainly on histologic specimens and not macroscopically or with in-vivo imaging. Degeneration may occur in the form of tendinitis, peritendinitis, enthesitis, or myotendinal junction abnormality. Distinct imaging findings exist for most of these forms. Many concepts that have been developed to explain tendon degeneration have been applied on virtually all tendons in the human body. They can be grouped into those which focus on hypovascularization, on biomechanical overload, and on degeneration secondary to other underlying disease. Tendon rupture seems, in many cases, to be the final stage of tendinitis. From this point of view, imaging may be used to predict the risk of tendon rupture together with other intrinsic and with extrinsic parameters. These considerations result in the concept of the "vulnerable zone" and of the "critical phase" in which tendon ruptures may predominantly occur.

Relation of cholesterol-year score to severity of calcific atherosclerosis and tissue deposition in homozygous familial hypercholesterolemia

The high concentrations of low-density lipoprotein cholesterol in plasma lead to accelerated atherosclerosis in patients homozygous for familial hypercholesterolemia (FH). We addressed the hypothesis that lipid deposition in the arterial vasculature and in nonvascular tissues in these patients correlates with both the duration and severity of their hypercholesterolemia. The severity of calcific atherosclerosis was defined by calcification scores and a calcified volume determined by electron beam tomography. The extent of tendinous xanthomatosis was quantitated by computed tomography. A cholesterol-year score was calculated based on the age and the yearly mean serum cholesterol concentration of each patient. Seventeen patients homozygous for FH were followed up. The average total cholesterol concentration in the study group was 780 +/- 231 mg/dl (20.2 mmol/L), and the cholesterol-year scores ranged from 2,172 mg-year/dl (56 mmol-year/L) to 32,260 mg-year/dl (834 mmol-year/L). Achilles tendon width (r=0.86) and cross-sectional area (r=0.81; both p <0.001) were best correlated with the cholesterol-year score. In addition, the coronary (r=0.61; p<0.05), ostial (r=0.45; p<0.05), and total (r= 0.77; p<0.001) calcification atherosclerosis scores all were best correlated with the cholesterol-year score. Calcific atherosclerosis was not observed in these patients until the cholesterol-year score exceeded 10,000 mg-year/dl (260 mmol-year/L). These findings establish a direct association of cholesterol-year with extravascular lipid deposition in tissues of patients with FH. The cholesterol-year score may be useful in defining the risk of atherosclerosis in patients with more common forms of hypercholesterolemia.

Magnetic resonance imaging of Achilles tendon xanthomas using a fat-water discrimination technique at 0.1 T

RATIONALE AND OBJECTIVES

Tendon xanthomas are atherosclerotic plaque like collections of lipids that develop with age in the Achilles tendons of patients having familial hypercholesterolemia (FH). We tested a fat-water discrimination technique for imaging Achilles tendon xanthomatosis.

METHODS

We used the spin-warp imaging technique optimized for low-field magnetic resonance (MR) imaging to obtain separate fat and water images of the Achilles tendon. Seven patients with FH, two patients with normal tendons, and three patients with other tendon pathology were studied.

RESULTS

Normal tendons showed an intensity near or equal to that of the noisy background in all images. Compared with the background, the intensity of the FH tendons was approximately fivefold greater in magnitude images, fourfold in fat images, and 10-fold in water images.

CONCLUSION

The method sensitively detected even subtle xanthomatosis in young patients, but differentiation of xanthomas from other pathologic lesions was possible with this method only when the tendons were significantly thickened.

Sonography of the Achilles tendon in hypercholesterolaemia

OBJECTIVES

Tendon xanthomas cause thickening of the tendon and are an important sign in monogenic familial hypercholesterolaemia (FH). The aim of our study was to investigate the usefulness of achilles tendon sonography in detecting FH patients. Special attention was paid to structural abnormalities of the achilles tendon.

DESIGN

A clinical study with methodological testing.

SETTING

Patients suspected of having FH were sent to the out-patient Department of Medicine from other departments of Turku University Central Hospital and from primary care units. The patients were studied by high-frequency ultrasound before more exact typing of the lipid disorder. An additional study of normolipidaemic volunteers and a phantom study were also carried out.

SUBJECTS

Forty FH patients, 51 non-FH hypercholesterolaemia patients and 41 normolipidaemic volunteers were included in the study. MAIN OUTCOME OF MEASURES: The thickness of the tendon was measured and the tendon structure and its echogenicity were recorded.

RESULTS

Twenty-five out of 40 (63%) FH patients had distinctly thickened tendons (men more than 10 mm, women more than 9 mm). Thirty-six (90%) had a typical structural alteration of low or mixed echogenicity of the tendon. Three non-FH patients were found to have xanthomas on sonography.

CONCLUSIONS

We conclude that ultrasonography is a sensitive method of detecting xanthomas that reveals the altered tendon structure even in xanthomatous tendons of normal thickness.

Ultrasonography in the detection of Achilles tendon xanthomata in heterozygous familial hypercholesterolemia

We have examined the usefulness of ultrasound (US) in the detection of Achilles tendon (AT) xanthomata in heterozygous familial hypercholesterolemia. Our study is based on 30 adult subjects with heterozygous familial hypercholesterolemia (FH) (16 men, 14 women), 27 subjects with other non-familial forms of severe hypercholesterolemia (non-FH) with serum total cholesterol levels > or = 8 mmol/l (13 men and 14 women) and 31 subjects without marked hypercholesterolemia of the same age (control group; serum total cholesterol < 8 mmol/l) (15 men, 16 women). The three groups were comparable with respect to age, sex and body mass index. In the control group the mean sagittal thickness of AT was 4.5 mm (95% CI 3.2, 5.9 mm) and the mean coronal breadth of AT 11.0 (95% CI 9.0, 13.0 mm). Mean thickness of AT was 4.9 (range 4-7) mm in the non-FH group and 11.1 (5-16) mm in the FH group. The mean breadth of AT was in these groups 12.0 (10-17) mm and 19.2 (12-27) mm, respectively. Using the upper 95% confidence interval cut-off point in the control group as a criterion for normal AT thickness and breadth, 6 (22%) of non-FH and 29 (97%) of FH patients had increased AT thickness and 5 (19%) vs. 26 (87%) patients had increased AT breadth, respectively. The sensitivity of AT thickness for identifying FH was 0.97, specificity 0.78 and positive predictive value 0.83. The sensitivity of AT breadth in identifying FH was 0.87, specificity 0.81 and positive predictive value 0.84. None of the control subjects and none of the non-FH patients showed structural abnormalities of AT in the US, whereas 89% of FH-patients showed hypoechogenicity of AT. FH-score obtained by summing up the number of abnormal US findings gave a sensitivity of 0.93, a specificity of 0.96 and a positive predictive value of 0.96 for AT US in discriminating FH from non-FH. In conclusion, US examination of AT is a useful method in the detection of AT xanthomata and thus of help in the diagnosis of heterozygous FH.

Magnetic resonance imaging of Achilles tendon xanthomas in familial hypercholesterolemia

The demonstration of tendon xanthomas is helpful in diagnosing heterozygous familial hypercholesterolemia, but in many patients lipid may accumulate without clinical abnormality being present. We investigated the possibility of detecting the lipid element with magnetic resonance (MR) imaging in seven patients with familial hypercholesterolemia and six controls. Although the mean relative signal intensities measured on long TR/TE spin echo sequences of the tendon were significantly higher in patients than in controls, the lack of such elevation does not rule out the presence of such lesions. In vitro measurements indicated that the signal intensity of triglycerides was quenched by cholesterolesters. The anatomic findings of MR imaging were compared with those of ultrasonography (US), showing excellent correlation in measurements between MR images and US [r(S) = 0.95 and 0.97 respectively]. MR imaging and US provide equal information on the anatomy of the Achilles tendon; as an abnormally increased signal intensity within the xanthoma on MRI was found in only a minority of our patients, the value of MRI in the demonstration of Achilles tendon xanthomas is limited when using conventional T1 and T2 spin echo sequences.

Computed tomography of tendinous xanthomata in cerebrotendinous xanthomatosis

Tendinous xanthomata with maximum expression on Achilles tendons are a characteristic feature of cerebrotendinous xanthomatosis, a rare autosomal recessive lipid storage disease. Twenty patients are under review; three of them, at different stages of the disease, underwent computed tomographic (CT) examination. CT demonstrates with a high degree of accuracy the increased size of the tendon and its heterogeneous structure resulting from cholesterol and cholestanol crystal deposits.

An ultrasonographic method for detection of Achilles tendon xanthomas in familial hypercholesterolemia

The diagnosis of familial hypercholesterolemia (FH) is frequently made on clinical grounds and detection of tendon xanthomas is crucial for that. In order to clarify whether ultrasonography (US) can be used as a reliable and practical method for detection of Achilles tendon xanthomas in FH, the Achilles tendon thickness in the sagittal section was examined by US in 15 patients with heterozygous FH and 34 normocholesterolemic subjects. US visualized clearly the anterior and posterior borders of the Achilles tendon. The Achilles tendon thickness determined by US correlated with that measured by conventional radiography (r = 0.99). The mean values +/- SD of the Achilles tendon thickness determined by US were 4.5 +/- 0.5 mm in the normal controls and 11.9 +/- 5.1 mm in the patients and the difference was significant (P less than 0.001). In 13 of 15 patients, US visualized thickened Achilles tendons with convex shape in the sagittal section. All the thickened Achilles tendons revealed by US were confirmed by radiography. The data indicate that US can detect Achilles tendons thickened by xanthomas. We conclude that US is a useful aid in the clinical diagnosis of FH.

Ultrasonography of achilles tendons in primary hypercholesterolemia. Comparison with computed tomography

Tendon xanthoma are a hallmark of familial hypercholesterolemia and are among its earliest clinical manifestations. Achilles tendon size, advanced to a generally accepted marker, is virtually specific for the disease and easily accessible for measurement. Hypercholesterolemic patients with coronary heart disease have been reported to have larger diameters of the Achilles tendons than patients without coronary problems. Furthermore, Achilles tendon xanthomas have been shown to regress with treatment of the lipid disorder. Mainly radiological procedures were applied in the past to evaluate the diameters of the Achilles tendon but their use is limited by radiation protection. We have used real-time ultrasonography to evaluate the Achilles tendons of 38 patients with primary hypercholesterolemia and 32 normocholesterolemic controls. The anterior posterior diameter in the patients was 13.4 +/- 5.9 mm (range 6-20 mm) and 5.7 +/- 0.7 mm (range 5-8 mm) in the control group. In 8 patients with newly diagnosed and previously untreated hypercholesterolemia the thickness correlated highly with their age. The Achilles tendons in about half of the patients (n = 21) showed a homogeneous thickening, whereas the others revealed an inhomogeneous thickening indicating the presence of circumscribed xanthoma. Upon comparison of the ultrasonographic procedure with an established method (computed tomography) in 18 patients and 8 normal volunteers a highly significant correlation (r = 0.96) proved the validity of the sonography. We show that real time ultrasonography is a valid procedure to assess Achilles tendon diameters in patients with primary hypercholesterolemia. It can be applied frequently and may be useful to follow xanthoma regression during lipid lowering treatment.

Changes in lipid and lipoprotein levels and Achilles tendon diameters and indices in familial hypercholesterolaemic patients with tendinous xanthomatosis treated by diet and bezafibrate for 2 years

Thirteen young adult patients suffering from heterozygotic familial hypercholesterolaemia with tendinous xanthomatosis, previously treated with a suitable special diet, were studied to assess the effect of bezafibrate, given for 2 years at a dose of 800 mg/day, on plasma lipid and lipoprotein levels and on changes in size of the Achilles tendon xanthomas. Measurements were made before and at intervals during treatment, the tendinous xanthomas being measured by an echographic procedure to give data on antero-posterior and lateral diameters, thus enabling an Achilles tendon index to be defined. The results confirm the hypolipidaemic activity of bezafibrate, changes in the levels of total cholesterol, triglycerides, lipids and lipoproteins (LDL, VLDL and HDL) being similar in direction and magnitude to those reported previously. A significant regression in the size of the Achilles tendon xanthomas was observed in 11 of the 13 patients, and the regression in the Achilles tendon index correlated significantly with a favourable change in the ratio HDL/LDL + VLDL. It is suggested that, as a result of this objective observation, a favourable effect of bezafibrate treatment would possibly be seen on the anatomical atheromatous lesions which are usual in this type of hyperlipidaemia.