Surgical and Medical Treatment of Osteoporosis

Principles and Practice

Peter V. Giannoudis, Thomas A. Einhorn, Peter V. Giannoudis, Thomas A. Einhorn

• Éditeur: CRC Press
• Année: 2020
• ISBN:
  9781498732291
• Édition: 1
• Sujet: Medicina
• Sous-sujet: Teoria, pratica e riferimenti medici

Osteoporosis is the most common bone disease and is associated with pathological fractures that can lead to significant morbidity. It represents an economic burden to the health care system, directly linked to an ageing population. Guidelines on osteoporosis prevention have been published but these do not provide the required specialised knowledge

1

Definition, risk factors, and epidemiology of osteoporosis

Enrique Guerado and Enrique Caso

Definition

Osteoporosis is the x-ray image of osteopenia—a diminution of the bone mass volume. Although pathologic in younger people, osteoporosis is a normal physiologic situation in elderly persons, particularly women. Yet osteoporosis has always been considered to be pathologic, and the word osteoporosis is used every day in orthopedic clinics. A homogeneous diminution of bone density under x-ray can also be the product of a reduction of bone tissue calcification, a disease called osteomalacia, which is always a pathologic situation.

When we say that a patient has osteoporosis, we actually mean that she or he has osteopenia. In clinical practice, osteoporosis is retrospectively recognized when a patient experiences a low-energy trauma, provoking what is termed a “fragility fracture” (1). Therefore, the definition of osteoporosis is very much related to the reduction of bone strength (2), secondary to an abnormal bone architecture (3,4); in consequence, osteoporosis and fractures are commonly, but wrongly, studied as the same disease. However, since the sensitivity of the clinical presentation of osteoporosis or its visibility in a simple x-ray projection—requiring a diminution of up to 20% of the mineralized bone matrix for bone mass loss to be detectable—is very low, a more accurate definition is needed.

The World Health Organization’s (WHO) definition of osteoporosis is based on densitometry findings. An individual with a bone mass index 2.5 standard deviations (SDs) or more below the average value for young healthy women would be considered to be osteoporotic (5). Although no alternative objective standard has been proposed, this definition is unrelated to the normal situation of elderly persons, for whom, in general, bone deterioration is just a part of overall body decline.

On the basis of the WHO definition, densitometry is considered by patients’ associations to be the gold standard for the diagnosis of osteoporosis, even for older persons, an attitude that has led some authors to criticize this definition, accusing pharmaceutical companies of sponsoring the characterization of diseases (6–8) and of systematically distorting both the evidence and evidence-based medicine and guidelines (9,10).

According to the industry, all persons presenting osteoporosis, under the WHO densitometry definition, should receive pharmaceutical treatment, and this recommendation is often at odds with the actual clinical situation (5). On the one hand, although all postmenopausal women will present osteoporosis, pharmaceutical companies assert that from a given age, the entire population should be pharmacologically treated for this disease. In consequence, for the majority of physicians and orthopedic surgeons, the elderly nontreated population are in fact undertreated patients. However, this outlook is not corroborated in clinical practice; as far as complications of osteoporosis are concerned, only a minority of elderly persons present “fragility fractures,” according to technological evaluation agencies (11). In this respect, health technology agencies have published data obtained from five independent evaluations of the predictive performance of bone density measurements. Depending on the threshold values used and the assumed lifetime incidence of hip fracture, these studies have reported predictive values for positive results in bone mass index tests ranging from 8% to 36% (12). Similarly, recent systematic reviews have concluded that there is insufficient evidence to inform the choice of which bone turnover marker should be used in routine clinical practice to monitor the response to osteoporosis treatment (13).

In view of these considerations, the overriding research priority should be to identify promising treatment-test combinations for evaluation in methodologically rigorous randomized controlled trials (RCTs). In order to determine whether or not bone turnover marker monitoring actually improves treatment decisions, and ultimately impacts on patient outcomes in terms of reduced incidence of fracture, well-designed RCTs are needed (13). Such projects should also focus on the multifactor etiology (comorbidity, type and circumstances of trauma, polypharmacy, previous fractures, hereditary, menopause, etc.) of broken bones. International registries represent a major step toward achieving this approach and contribute to obtaining a more accurate definition of the disease.

There is often much confusion between the concept of a fracture patient with osteoporosis versus one with an “osteoporotic fracture.” The definition of “osteoporotic fracture” arouses controversy, as osteoporosis is merely one of many independent variables—and in many instances not necessarily the most important one—also including age, dementia, and/or cataracts, in the clinical background of the disease. Obviously, when an elderly person is admitted to hospital with a hip fracture, and with concurrent cataracts that may provoke falls, this patient is not said to have suffered an “ophthalmic fracture,” even though the origin of the fracture could be a fall caused by defective vision (14). Furthermore, although all elderly persons are osteopenic, only a small percentage of them will suffer a fall, and less than half of those who do will develop an injury as a result (15). Moreover, persons aged 65 years or older who have a fall are likely to suffer another one within a year but will not necessarily experience a fracture (16).

Today, it is fairly well established that falls are the main cause of hip fractures, and also that although osteoporosis provokes more severe fracture patterns than those found in nonosteoporotic bones, this disease is not the origin of hip or wrist fractures. Only with respect to the treatment provided, and not as regards the physiopa...