The HIV lipodystrophy syndrome, which includes metabolic complications and altered fat distribution, is of major importance in HIV therapy. The metabolic abnormalities may harbor a significant risk of developing cardiovascular disease, with as yet unknown consequences. In addition, several studies report a reduced quality of life in patients with body habitus changes leading to reduced treatment adherence. Despite the impact of lipodystrophy syndrome on HIV management, little is known about the pathogenesis, its prevention, diagnosis and treatment. Current data indicate a rather multifactorial pathogenesis where HIV infection, its therapy, and patient-related factors are major contributors. The lack of a clear and easy definition reflects the clinical heterogeneity, limits a clear diagnosis and impairs the comparison of results among clinical studies. Therapeutic and prevention strategies have so far been of only limited clinical success. Thus, general recommendations include dietary changes and life style modifications, altering antiretroviral drug therapy (replacement of protease inhibitors with NNRTI or replacement of stavudine and zidovudine with e.g. abacavir or tenofovir), and finally, the use of metabolically active drugs. Here we summarize the pathogenesis, diagnosis and treatment options of the HIV lipodystrophy syndrome.

Lipodystrophy was originally described as a condition characterized by regional or generalized loss of subcutaneous fat. The non-HIV-associated forms, such as congenital or familial partial lipodystrophy, have a very low prevalence. Generally, these forms are associated with complex metabolic abnormalities and are difficult to treat. The term "lipodystrophy syndrome" in association with HIV, was introduced to describe a complex medical condition including the apparent abnormal fat redistribution and metabolic disturbances seen in HIV-patients receiving protease inhibitor therapy (Carr 1998). But, even years after its first description, there is still no consensus on a case definition for lipodystrophy syndrome in HIV patients. Thus, the diagnosis of lipodystrophy in clinical practice often relies on a more individual interpretation than on an evaluated classification. Finally, changes in the fat distribution have to be considered as being rather dynamic processes. In most cases, lipoatrophy is clinically diagnosed when significant fat loss has already occurred.

HIV-associated lipodystrophy includes both clinical and metabolic alterations. The most prominent clinical sign is a loss of subcutaneous fat (lipoatrophy) in the face (periorbital, temporal), limbs, and buttocks. Prospective studies have demonstrated an initial increase in limb fat during the first months of therapy, followed by a progressive decline over the ensuing years (Mallon 2003). Peripheral fat loss can be accompanied by an accumulation of visceral fat, which can cause mild gastrointestinal symptoms. Truncal fat increases initially after therapy and then remains stable (Mallon 2003). Visceral obesity, as a singular feature of abnormal fat redistribution, appears to occur in only a minority of patients. Fat accumulation may also be found as dorsocervical fat pads ("buffalo hump") within the muscle and the liver. Female HIV patients sometimes complain about painful breast enlargement, which has been attributed to the lipodystrophy syndrome. Whether gynecomastia in male patients is a component of the syndrome remains unclear. There is now accumulating evidence that the major clinical components - lipoatrophy, central adiposity and the combination of both - result from different pathogenetic developmental processes.

The prevalence of lipodystrophy syndrome has been estimated to be between 30 and 50 %, based on cross-sectional studies. A prospective study over an 18-month period after initiation of therapy revealed a prevalence of 17 % (Martinez 2001). Lipodystrophy, and in particular lipoatrophy, has been observed most frequently in patients receiving a combination regimen of nucleoside analogues and protease inhibitors, although almost all antiretroviral drug combinations can be associated with fat redistribution. The risk of the syndrome increases with the duration of treatment, the age of the patient and the level of immunodeficiency. Lipodystrophy has been observed during the therapy of both the acute and chronic states of HIV infection and even following post-exposure prophylaxis. Children can be affected, like adults, with clinical fat redistribution shortly after initiation or change of antiretroviral therapy. The evolution of the individual clinical components of the lipodystrophy syndrome is variable. Subcutaneous fat loss has been observed during exclusive therapy with NRTIs but probably develops faster under a combination of NRTIs and protease inhibitors. The nucleoside analogue linked most strongly to lipoatrophy is stavudine, particularly when used in combination with didanosine. Tenofovir combined with lamivudine and efavirenz is associated with less loss of limb fat than stavudine in a similar combination in therapy-naïve HIV patients (Gallant 2004). Single case reports even describe body habitus changes compatible with the lipodystrophy phenotype in antiretroviral therapy-naïve patients.

Frequently, complex metabolic alterations are associated with the described body shape alterations. These include peripheral and hepatic insulin resistance, impaired glucose tolerance, type 2 diabetes, hypertriglyceridemia, hypercholesterolemia, increased free fatty acids (FFA), and decreased high density lipoprotein (HDL). Often these metabolic abnormalities appear or deteriorate before the manifestation of fat redistribution. The prevalence of insulin resistance and glucose intolerance has been reported in the literature at 20 to 50% depending on the study design and measurement methods. Frank diabetes is less frequent with a prevalence of between 1 and 6 %. Lipodystrophic patients present with the highest rates of metabolic disturbances.

Hyperlipidemias are a frequently observed side effect of antiretroviral therapy, especially in combinations that include protease inhibitors. Given that many HIV patients present with already decreased HDL levels, these are not further reduced by antiretroviral drugs. Hypertriglceridemias, especially in patients with evidence of body-fat abnormalities, are the leading lipid abnormality either alone or in combination with hypercholesterinemia. Several weeks after initiation or change of HIV therapy, lipid levels usually reach a plateau and remain stable. All protease inhibitors can potentially lead to hyperlipidemia, although to different extents. For example, atazanavir (Reyataz™) appears to be less frequently associated with dyslipidemia and insulin resistance. In contrast, ritonavir (Norvir™) often leads to hypertriglyceridemia correlating to the drug levels.

Recently, more signs and symptoms have been described in association with the lipodystrophy syndrome. Their pathogenetic relationship to fat redistribution and metabolic changes has not yet been fully evaluated. Thus, future studies need to assess whether conditions such as dry skin, ingrown toenails, aseptic hip necrosis, osteopenia and osteoporosis are linked to the lipodystrophy syndrome or are caused by independent drug or disease-related effects.

The fat redistribution and disturbances in glucose and fat metabolism resemble a clinical situation that is known as the "metabolic syndrome" in HIV-negative patients. This condition includes symptoms such as central adipositas, insulin resistance and hyperinsulinemia, hyperlipidemia (high LDL, Lp(a) hypertriglyceridemia and low HDL) and hypercoagulopathy. Given the well-established cardiovascular risk resulting from this metabolic syndrome, there is growing concern about a potential therapy-related increased risk of myocardial infarction in HIV patients. These fears are further sustained by reports of arterial hypertension on HAART (Seaberg 2005), a high rate of smoking among HIV patients and increased levels of tissue plasminogen activator (tPA) and plasminogen activator inhibitor-1 (PAI-1) in patients with lipodystrophy. Although many of the, mainly retrospective, studies dealing with this issue are inconclusive, data from a large international study (D:A:D study) provide evidence for an increased relative risk of myocardial infarction during the first 7 years of HAART (Friis-Møller 2003, El-Sadr 2005). The incidence of myocardial infarction increased from 1.39/1,000 patient years in those not exposed to HAART, to 2.53/1,000 patient years in those exposed for < 1 year, to 6.07/1,000 patient years in those exposed for ≥ 6 years (RR compared to no exposure: 4.38 [95 % CI 2.39 to 8.04], p = 0.0001). After adjustment for other potential risk factors, there was a 1.17-fold [1.11 to 1.24] increased risk of myocardial infarction per additional year of combined ART exposure (El-Sadr 2005). It is, however, of note that older age, male gender, smoking, diabetes mellitus, and pre-existing coronary artery disease were still associated with a higher risk of sustaining cardiovascular events than HAART in this study. Although the CHD risk profile in D:A:D patients worsened over time, the risk of myocardial infarction decreased over time after controlling for these changes (Sabin 2005). Several other studies used ultrasonography to measure the thickness of the carotid intima media or endothelial function to predict the cardiovascular risk. Some of these investigations found abnormal test results (e.g. reduced flow-mediated dilation) that correlated either with the use of protease inhibitors or the presence of dyslipidemia (Currier 2003). Long-term follow-up results will be necessary to substantiate these preliminary observations. While there is some indication of an increased rate of coronary artery disease during HAART, the benefit of suppressed viral replication and improved immune function resulting in reduced morbidity and mortality, clearly argues for the use of antiretroviral drugs according to current international guidelines. It seems obvious however, that pre-existing cardiovascular risk factors in individual patients need to be considered more carefully before starting or switching HAART.

Recommendations such as the National Cholesterol Education Program (NECP) have been proposed for non-HIV-infected patients with similar risk constellations. These guidelines are being proposed by some authors for HIV patients as well (Dube 2000, Schambelan 2002, Grinspoon 2005). According to these recommendations, the overall cardiovascular risk in HIV-infected patients can be determined from specific risk factors by using the Framingham equation. Prediction of coronary heart disease using this equation, however, may have some limitations. A 10-year CHD risk estimation at any time point is determined by the individual's past and expected future lipid levels (best assessed as area under the curve). Hyperlipidemia in many treated HIV patients, however, does not follow the 10-year time course seen in the "normal population" due to frequent therapy changes that may lower total cholesterol, increase HDL, and improve atherogenic risk. Thus, the validity of this calculation for the long-term cardiovascular risk assessment in young patients with changing lipid levels and medication regimens requires further studies.

Clearly, more clinical studies are necessary to assess whether these recommendations are also applicable in the presence of HIV and to determine the clinical value of lipid lowering drug therapy in these patients. Most importantly, the information about drug interactions of lipid lowering and antiretroviral drugs is still incomplete. The accumulation of pre-existing and drug-related risk factors will get more clinical attention, because, by improving the HIV-associated morbidity and mortality, HAART consequently increases an additional relevant cardiovascular risk factor: the age of patients who are effectively treated with antiretroviral drugs.

For a better understanding of the pathogenesis of the complex metabolic abnormalities, it is useful to separate individual aspects of the lipodystrophy syndrome: adipocytes/fat redistribution, lipid metabolism, and carbohydrate metabolism. This is because it is very likely that the lipodystrophy syndrome is not a stereotypic syndrome but rather an amalgam of miscellaneous clinical features, with perhaps multifactorial causes. Studies published during recent years provide evidence for two fundamental assumptions: firstly, lipoatrophy and lipoaccumulation result from divergent or only partially overlapping pathogenetic reasons. Secondly, NRTIs, NNRTIs, PIs, and even drugs within each class contribute to the lipodystrophy syndrome and its individual features by different, probably overlapping and certainly synergistic mechanisms.

The patterns of fat redistribution in patients who are exclusively receiving NRTIs are unlike those observed in patients during PI therapy. Peripheral fat loss is the major symptom observed in NRTI therapy (particularly using stavudine and didanosine combinations), although a few clinical studies have described a minimal intra-abdominal fat increase in these patients, which is clearly less than under PIs. Given that, commonly, only a mild increase in triglycerides has been observed, exclusive NRTI therapy seems to be of minor impact on lipid metabolism. Postprandially elevated FFA in patients with lipodystrophy, together with in vitro experiments, have led to the hypothesis that NRTIs could impair fatty acid binding proteins (FABP) which are responsible for cellular fat uptake and intracellular fat transport. In contrast, addition of stavudine (Zerit™) to a dual PI regimen does not result in a further increase in the total cholesterol or triglyceride levels.

PIs account for the majority of metabolic abnormalities associated with lipodystrophy syndrome. Numerous studies report increases in the levels of total triglycerides and triglyceride-rich lipoproteins (VLDL) accompanied by raised LDL levels after initiation of PI therapy (Walli 1998). Conversely, these parameters improved substantially in most studies after discontinuation of the PI or on switching to abacavir (Ziagen™) or nevirapine (Viramune™). The hyperlipidemic changes are frequently associated with hyperinsulinemia and/or insulin resistance.

It has been proposed, based on in vitro experiments, that PIs such as saquinavir (Invirase™), indinavir (Crixivan™), and ritonavir (Norvir™) are able to inhibit proteasomal degradation of apolipoprotein B leading to intracellular stockpiling of this lipoprotein and excessive release in response to FFA (Liang 2001). Using stable isotopes in vivo, other authors demonstrate a dramatic increase in FFA turnover together with increased lipolysis and decreased clearance of triglyceride-rich VLDL and chylomicrons (Shekar 2002). These conditions point towards an impaired postprandial insulin-mediated lipid metabolism, since insulin, on the one hand, normally inhibits lipolysis and, on the other hand, increases uptake of FFA, triglyceride synthesis, and fat oxidation in favor of glucose oxidation.

So far, it remains unclear whether impaired insulin action eventually leads to dyslipidemia, or whether hyperlipidemia is responsible for reduced insulin function and insulin resistance in the periphery. Presumably, both mechanisms are important given that some PIs (e.g. indinavir) have been shown to induce insulin resistance without changes occurring in lipid metabolism after short-term administration (Noor 2001, Noor 2002), whereas other PIs (e.g. ritonavir) have been demonstrated to cause mainly hypertriglyceridemia due to increased hepatic synthesis without major changes occurring in glucose metabolism (Purnell 2000). However, comparative clinical studies on the association of different PIs with insulin resistance are still lacking.

It is reasonable to speculate that lipid abnormalities and, in particular increased FFA levels, contribute substantially to the peripheral and central insulin resistance of skeletal muscles and the liver, presumably due to the increased storage of lipids in these organs (Gan 2002). Given this hypothesis, the visceral adiposity could reflect the adaptation of the body in response to raised FFA concentrations and an attempt to minimize the lipotoxic damage to other organs.

Several in vitro experiments have indicated that almost all PIs can potentially lead to insulin resistance in adipocytes. Short-term administration of indinavir caused an acute and reversible state of peripheral insulin resistance in healthy volunteers, which was determined in an euglycemic-hyperinsulinemic clamp. These effects are most likely caused by the inhibition of glucose transport mediated by GLUT-4, the predominant transporter involved in insulin-stimulated cellular glucose uptake in humans (Murata 2002). A common structural component found in most PIs has been proposed to cause GLUT-4 inhibition (Hertel 2004). In some patients with lipodystrophy, additional impairment of glucose phosphorylation may contribute to insulin resistance (Behrens 2002). This is presumably due to an impaired insulin-mediated suppression of lipolysis and subsequently increased FFA levels (Behrens 2002, van der Valk 2001) and accumulation of intramyocellular lipids. Peripheral insulin resistance may also account for an increase in the resting energy expenditure in HIV lipodystrophy and a blunted insulin-mediated thermogenesis.

Both the lack of a formal definition and uncertainty about the pathogenesis and possible long-term consequences, leads to a continuing discussion about appropriate guidelines for the assessment and management of HIV lipodystrophy syndrome and its metabolic abnormalities. Outside clinical studies, the diagnosis relies principally on the occurrence of apparent clinical signs and the patient reporting them. A standardized data collection form may assist in diagnosis (Grinspoon 2005). This appears sufficient for the routine clinical assessment, especially when the body habitus changes develop rather rapidly and severely. For clinical investigations however, especially in epidemiological and interventional studies, more reliable measurements are required. But so far, no technique has demonstrated sufficient sensitivity, specificity or predictive value to definitively diagnose the HIV lipodystrophy syndrome by comparison with results obtained from a "normal" population. A recent multicenter study to develop an objective and broadly applicable case definition proposes a model including age, sex, duration of HIV infection, HIV disease stage, waist-to-hip ratio, anion gap, serum HDL cholesterol, trunk to peripheral fat ratio, percentage leg fat, and intra-abdominal to extra-abdominal fat ratio. Using these parameters, the diagnosis of lipodystrophy had a 79 % sensitivity and 80 % specificity.

Despite individual limitations, several techniques are suitable for measuring regional fat distribution. These include dual energy x-ray absorptiometry (DEXA), computer tomography (CT), magnetic resonance imaging (MRI) and sonography. Anthropometric measurements are safe, portable, cheap and much easier to perform than imaging techniques. Waist circumference alone, as well as sagittal diameter, are more sensitive and specific measures than waist-to-hip ratio. Repeated measurements of skin fold thickness can be useful for individual long-term monitoring but need to be performed by an experienced person.

The main imaging techniques (MRI, CT, DEXA) differentiate tissues on the basis of density. Single-slice measurements of the abdomen and extremities (subcutaneous adipose tissue = SAT, visceral adipose tissue = VAT) and more complex three-dimensional reconstructions have been used to calculate regional or total body fat. Limitations of these methods include most notably their expense, availability and radiation exposure (CT). Consequently, CT and MRI should only be considered in routine clinical practice for selected patients (e.g. extended dorso-cervical fat pads, differential diagnosis of non-benign processes and infections).

Table 2. Proposed grading scale for lipodystrophy based on lipodystrophy case definition cores relative to the subjective physician assessment-derived total lipodystrophy severity score (according to Carr & Law 2003).

DEXA is appropriate for examining appendicular fat, which is comprised almost entirely of SAT, and has been successfully employed in epidemiological studies. However, SAT and VAT cannot be distinguished by DEXA, which therefore limits the evaluation of changes in truncal fat. Application of sonography to measure specific adipose compartments, including those in the face, requires experienced investigators and has been minimally applied in HIV infection so far. Bioelectrical impedance analysis estimates the whole body composition and cannot be recommended for measurement of abnormal fat distribution.

Patients should routinely be questioned and examined for cardiovascular risk factors, such as smoking, hypertension, adiposity, type 2 diabetes, and family history. For an accurate assessment of blood lipid levels, it is recommended to obtain blood after a fasting of at least 8 hours. Total cholesterol and triglycerides together with LDL and HDL cholesterol should be obtained prior to the initiation of, or switch to, a new potent antiretroviral therapy and repeated 3 to 6 months later. Fasting glucose should be assessed with at least a similar frequency. The oral glucose tolerance test (OGTT) is a reliable and accurate instrument for evaluating insulin resistance and glucose intolerance. An OGTT may be indicated in patients with suspected insulin resistance such as those with adipositas (BMI > 27 kg/m²), a history of gestational diabetes and a fasting glucose level of 110 to 126 mg/dl (impaired fasting glucose). An intravenous glucose tolerance test or hyperinsulinemic-euglycemic clamp appears only feasible in clinical studies. The diagnosis of diabetes is based on fasting glucose levels > 126 mg/dl, glucose levels of > 200 mg/dl independent of fasting status, or a 2-hour OGTT glucose level above 200 mg/dl. Additional factors that could lead to or assist in the development of hyperlipidemia and/or insulin resistance always need to be considered (e.g. alcohol consumption, thyroid dysfunction, liver and kidney disease, hypogonadism, concurrent medication such as steroids, β-receptor blockers, thiazides, etc.).

So far, most attempts to improve or even reverse the abnormal fat distribution by modification of the antiretroviral treatment have shown only modest clinical success. In particular, peripheral fat loss appears to be resistant to most therapeutic interventions. The metabolic components of the syndrome may be easier to improve (Table 3).

Dietary interventions are commonly accepted as the first therapeutic option for hyperlipidemia, especially hypertriglyceridemia. Use of NCEP guidelines may reduce total cholesterol and triglycerides by 11 or 21 %, respectively. Whenever possible, dietary restriction of the total fat intake to 25-35 % of the total caloric intake should be a part of the treatment in conjunction with lipid-lowering drugs. Consultation with professional and experienced dieticians should be considered for HIV-infected patients and their partners. Patients with excessive hypertriglyceridemia (>1000 mg/dl) may benefit from a very low fat diet and alcohol abstinence to reduce the risk of pancreatitis, especially if there is a positive family history or concurrent medications that may harbor a risk of developing pancreatitis. Regular exercise may have beneficial effects, not only on triglycerides and insulin resistance, but probably also on fat redistribution (reduction in truncal fat and intramyocellular fat) and should be considered in all HIV-infected patients (Driscoll 2004a). All patients should be advised and supported to cease smoking in order to reduce the cardiovascular risk. Cessation of smoking is more likely to reduce cardiovascular risk than any choice or change of antiretroviral therapy or use of any lipid-lowering drug.

Given the extensive indications that PIs are the culprits substantially contributing to the metabolic side effects, numerous attempts have tried to substitute the PI component of a regimen with nevirapine, efavirenz, or abacavir. Similarly, given the close association of stavudine-based therapy with lipoatrophy, replacement of this thymidine nucleoside analogue by, for example, abacavir or tenofovir has been evaluated in several studies. Indeed, these "switch studies" have demonstrated substantial improvement, although not normalization, of serum lipids (total and LDL cholesterol, triglycerides) and/or insulin resistance in many patients. In patients with hyperlipidemia, substitution of PIs with alternative PIs that have less metabolic side effects (e.g. atazanavir) has also been proven to be a successful strategy (Martinez 2005, Moebius 2005). Protease inhibitor cessation has not been shown to improve lipoatrophy. However, stopping administration of the thymidine nucleoside analogue stavudine or zidovudine usually leads to a slow recovery (over months and years) measured by DEXA and moderate clinical increase in limb fat (Moyle 2005). Under restricted inclusion criteria and study conditions, most patients maintained complete viral suppression after changes to the HAART regimen, but not all of these studies included control groups with unchanged antiretroviral therapy. Recently, a pilot study evaluating the effect of uridine (NucleomaxX™) on lipoatrophy in HIV patients continuing their HAART regimen described a significant increase in subcutaneous fat after only three months (Sutinen 2005). Further studies with uridine, a sugar cane extract, will be necessary to fully assess the effectiveness and safety of this compound for patients with the lipodystrophy syndrome.

The most advantageous changes of metabolic parameters have been observed after replacement of the PI by nevirapine or abacavir. This option is, however, not always suitable, and the clinical benefit of effective viral suppression and improved immune function needs to be considered in view of the drug history, current viral load, and resistance mutations (Martinez 2003). When options are limited, antiretroviral drugs that may lead to elevation of lipid levels should not be withheld for fear of further exacerbating lipid disorders.

HMG-CoA reductase inhibitors have been successfully used in combination with dietary changes in HIV patients with increased total and LDL cholesterol. These drugs may decrease total and LDL cholesterol by about 25 % (Grinspoon 2005). Many of the statins (as well as itraconazole, erythromycin, diltiazem, etc.) share common metabolization pathways with PIs via the cytochrome P450 3A4 system, thereby potentially leading to additional side effects due to increased plasma levels of statins which can then cause liver and muscle toxicity. Based on limited pharmacokinetic and clinical studies, atorvastatin (Sortis™), fluvastatin (Lescol™), and pravastatin (Pravasin™), carefully administered at increasing doses, are the preferred agents for a carefully monitored therapy in HIV-infected patients on HAART. Lovastatin (Mevinacor™) and simvastatin (Zocor™) should be avoided due to their potential interaction with PIs.

Fibric acid analogues such as gemfibrozil or fenofibrate are particularly effective in reducing the triglyceride levels by up to 50 % (Rao 2004, Badoui 2004, Miller 2002, Calza 2003) and should be considered in patients with severe hypertriglyceridemia (>1000 mg/dl). Fibric acid analogues retain a supportive effect on lipoprotein lipase activity and can thereby lower LDL levels. Despite their potentially synergistic effect, co-administration of fibric acid analogues and statins in patients on HAART should only be used carefully in selected individuals, since both can cause rhabdomyolysis. Niacinic acid has been shown to only minimally improve the hyperlipidemia induced by HAART. It does, however, increase peripheral insulin resistance (Gerber 2004). Extended-release niacin (Niaspan™) has been shown to have beneficial effects mainly on triglycerides and was well tolerated at a dose of 2,000 mg daily in a study with 33 individuals (Dube 2005). Finally, it should be stressed that the long-term effects of lipid-lowering agents and their impact on cardiovascular outcomes, especially in HIV patients with moderate or severe hypertriglyceridemia, are unknown.

Recombinant growth hormone (e.g. Serostim™) at doses of 4-6 mg/d sc over a time course of 8-12 weeks has been demonstrated in some small studies to be a successful intervention for reducing visceral fat accumulation, but it also reduces subcutaneous fat (Kotler 2004). Unfortunately, these improvements have been shown to consistently reverse after the discontinuation of growth hormone therapy. Studies with lower maintenance doses have not been performed yet. The possible side effects associated with growth hormone therapy include arthralgia, peripheral edema, insulin resistance and hyperglycemia.

Surgical intervention (liposuction) for the treatment of local fat hypertrophy has been successfully performed, but appears to be associated with an increased risk of secondary infection, and recurrence of the fat accumulation is possible. For the treatment of facial lipoatrophy, repeated subcutaneous injection of substances such as poly-L-lactic acid (Sculptra™, New-Fill™), a resorbable molecule that promotes collagen formation, has been effectively used in HIV patients (Valantin 2003, Lafaurie 2003ž Guaraldi 2004, Mest 2004, Casavantes 2004). In 2004, Sculptra™ was approved by the Food and Drug Administration as an injectable filler to correct facial fat loss in people with human immunodeficiency virus. We recommend consultation with experienced specialists for surgical treatments and injection therapy. Further evaluation in long-term follow-up studies is necessary to fully assess the value of these methods.

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