Osteoporosis

Primary osteoporosis involves a loss of bone mass because bone formation becomes imbalanced with bone resorption. There are many types of secondary osteoporosis besides the typical primary osteoporosis seen with aging. Other causes of osteoporosis are termed secondary osteoporosis [ 5]. Secondary osteoporosis may be the result of altered calcium metabolism or altered collagen make-up of bone. Type I collagen is the primary collagen found in bone. Many mineral metabolism problems may cause a secondary osteoporosis including vitamin D deficiency, hyperparathyroidism, hyperthyroidism, renal disease, anticonvulsant use, and Paget‘s disease. Collagen-based bone structure problems can be the result of osteogenesis imperfecta, vitamin C deficiency, and steroid use [5].

According to the US National Osteoporosis Foundation, 80% of those affected by osteoporosis are women and 20% are men. Kanis et al have shown the femoral neck bone density decreases with age in men and women [ 6, 7]. Osteoporosis in men is common with aging and is often overlooked and undertreated [ 8]. All ethnic groups can be affected, although rates of osteoporosis are affected by ethnicity. Osteoporosis influences the emergence of fractures and their treatment.

Reduction in the quality of bone

Osteoporosis involves both a loss of bone mass, reduction in bone quality by microarchitectural deterioration of bone tissue, and reduced ability of bone to withstand loading. It is important to understand the difference between bone mineral density (BMD)—which reflects the calcium content—and the deterioration of bone quality measurable in reduced resistance to loading. Usually, the quality of bone reduces much more with age in cancellous bone than in cortical bone ( Table 24-1 ).

Bone is a living tissue with three main cell types: osteoblast, osteoclast, and osteocyte. Each cell line has an important role in maintenance of healthy bone. The osteoblast forms new bone in areas that were previously resorbed by the osteoclasts. Osteocytes are believed to provide the chemical signaling to osteoclasts and osteoblasts through the canaliculi found in lamellar bone. Peak bone mass is achieved between 25 and 30 years and is believed to decline thereafter. A state of equilibrium exists in the bone of young adults; bone is resorbed and replaced at even rates. This is important to heal minor bone damage that occurs with daily activity. By middle age, bone resorption continues but bone accretion is reduced. At menopause, the antiresorptive effects of estrogen are reduced and a rapid loss of bone mass occurs during the first 7 years after menopause. After 7 years the rate of bone loss slows but continues until death.

Bone can be divided into cortical and cancellous types. Both types change significantly with age. Cortical bone is normally found in the diaphyseal areas of long bones and the perimeter of flat bones. Cancellous bone predominates in the metaphyseal and epiphyseal areas of long bones, vertebrae, and flat bones. Distinctive changes to cortical and cancellous bones are described below.

It is well established that aging humans lose a substantial amount of bone mass that was present at 25 years. It is also documented that women over 40 lose more bone and at a faster rate than men [5, 8, 9]. Cortical bone at 25 years is dense, thick, and strong. The pattern of age-related cortical bone loss involves thinning long-bone cortices or cortical thickness loss with concomitant increase in medullary diameter, particularly in women ( Fig 24-1 ). Women show significant (P < .05) decreases in cortical thickness, bone mineral content, and cortical bone density when plotted against age. Men exhibit slight nonsignificant declines for cortical thickness, bone mineral content, and cortical bone density. Both men and women exhibit significant (P < .05) age-related increases in summed Haversian canal area values and Haversian canal number [ 10, 11]. The human body increases the diameter of the osteoporotic bone to give some increase in its bending and torsional strength. The osteoporotic skeleton increases the outer diameter to increase the bending stiffness. With the reduced bone mass, the inner diameter is also augmented because the bone volume and bone mass may not be enlarged. If we assume a diaphyseal bone is a tube, the formula Π/4(R4-r4) describes the calculation of the bending stiffness of a tube. Bending stiffness depends on the inner and outer radius of the tube. Dependence is as strong as exponent 4.

Cancellous bone undergoes many changes with both aging and osteoporosis. The trabeculae undergo osteoclast-mediated resorption with a diminished rate of osteoblastic bone deposition. This results in thinning of the trabeculae and disconnection of the trabeculae from each other and from the surrounding cortical bone. With aging, the bone trabeculae change in shape from flatter structures to more rod-like structures. These changes weaken the internal architecture of the cancellous bone making it more likely to fracture with minor trauma ( Fig 24-2 ).

Biomechanically the reduction of bone quality has been demonstrated for many different failure modes, implants, and bones [ 12].

Mechanisms of injury

There is a wide variety of injury mechanisms, from the usual low-energy fall from standing or sitting height to severe motor vehicle injuries.

Why are fragility fractures more frequent with age? Many factors contribute. Most fragility fractures occur after a low-energy fall. Falls occur in one third of community-dwelling people per year older than 65 years. 10% of falls in the elderly result in serious injury [6]. Women are more likely to sustain a fracture than men. Risk factors for falls are similar to those of fractures: previous falls, weakness, poor balance, gait disorders, and taking certain medications, such as psychoactive drugs, anticonvulsants, and antihypertensives [ 13– 15].

As people are living longer, they are also more active when older. In the elderly population motor vehicle collisions, being struck by a car as a pedestrian, falls from high, and burns are all increasingly common injuries.

In geriatric polytrauma patients, for each 1-year increase in age over 65 years, the probability of dying increases by 6.8%. Hepatic and renal diseases, cancer, and long-term steroid use have greatest negative impact on patient survival [ 16]. For care of the injured elderly patient, trauma centers have shown significantly better outcomes than acute care hospitals [ 17]. Therefore, triage of the injured elderly patient to a trauma center from the scene of injury is critical to improving outcomes.

In demographic studies, 28% of all traumatic deaths occur in the geriatric group despite being only 12% of the population. When controlled for severity, the elderly were six times as likely to die as their younger counterparts [ 18].

Comorbidities

The fragility fracture is only one part of the problem. Fragility fractures are much more common in patients with preexisting medical conditions—comorbidities. These comorbidities may contribute to the cause of the fracture and frequently complicate patient care. Comorbidities may dominate the situation in some cases and the fragility fracture may be secondary in importance. Some fracture survival scores use the presence of specific comorbidities to help predict patient outcomes [ 23, 24].

Common comorbidities in patients with fragility fractures include cardiac disease, dementia, renal dysfunction, pulmonary disease, hypertension, and diabetes. Each of these conditions is likely to be treated with at least one medication which leads to a situation referred to as polypharmacy. When more than three drugs are used, many patients will experience some level of drug-drug interaction. A consultation with a geriatrician or physician is useful in these situations to assist the orthopaedic trauma surgeon with management of these conditions and medications.

Compliance/adherence

The natural aging process limits the elderly in their ability to respond to injury. Many patients have difficulty being compliant with instructions because of frailty and/or dementia. Dementia is a common comorbidity in the fragility fracture population. Dementia is a chronic, fatal illness with relentless progression of decline in cognitive status. The patient with dementia finds it difficult or impossible to follow instructions given in physical therapy.

Delirium is much more common in patients who have dementia and up to 61% of patients with a hip fracture have delirium in the perioperative period [ 25]. Delirium is an acute and fluctuating alteration in mental status with inattention, confusion, and lack of mental clarity. There are hypoactive, hyperactive, and mixed forms of delirium. The hyperactive form often involves agitation, irritability, confusion, hallucinations, and loud verbal communications. The hypoactive form is notable for somnolence, diminished responsiveness, little or no speech, or reduced movement of the patient. The mixed variety involves a fluctuating course between these two forms. Delirium indicates a poor prognosis for the patient with fragility fracture. Hospital stay is lengthened and it becomes more likely that the delirious patient will have a complication. Delirious patients cannot effectively participate in their rehabilitation following fracture [25, 26].

Functional demands

The functional demands of the elderly are unique. Many elderly have little or no support from family and this varies from region to region. Elderly patients often require use of their upper extremities to assist with ambulation by using a cane or walker. It is impossible for most elderly patients to limit their weight bearing on an injured extremity. Both upper and lower extremities can be weight-bearing limbs. Therefore, any treatment plan devised for the older fracture patient must also consider their unique functional needs, preinjury living situation, and preinjury function.

Risk of surgery

At this stage the status of the patient should only be optimized if the measure lowers the risk of surgery. However, if the risk of surgery cannot be altered surgery should be performed without further delay. Delaying surgery would otherwise add additional, unnecessary risk that is.

Standard preoperative evaluation

The standard evaluation process follows a predefined and consented pathway [17] ( Table 24-2 ).

Typical situations that need action but should not delay surgery are:

• 
  

  Hydration to prevent cardiac dysfunction: nearly all elderly patients with a fragility fracture are dehydrated when admitted to hospital. Fluid resuscitation is also necessary to prevent hypotension when anesthesia is given

  
  
• 
  

  Strict glucose control before and during surgery: Keeping the serum glucose level between 80 and 180 mg/dL in the perioperative period helps to reduce infections as well as reducing both hypoglycemic and hyperglycemic complications

  
  
• 
  

  Correction of hypertension

  
  
• 
  

  Avoidance of chronic obstructive pulmonary disease exacerbation with bronchodilators

  
  
• 
  

  ß-blocking to prevent arrhythmia

  
  
• 
  

  Warming up in cases of hypothermia: there are many benefits to maintaining the patient‘s core body temperature between 36–37.5°. Specifically, there are reduced infection rates and fewer perioperative complications

The patient‘s psychological status must be carefully followed up to avoid delirium and subsequent complications. Intact skin condition, in particular, pressure sores and infection avoidance are vital. The patients’ preoperative functional status must be determined to assist with planning their care and understanding their prognosis.

Optimizing the medical situation

In few and clearly defined situations, the patient will need additional preoperative preparation and medical stabilization. As a rule the time needed should not exceed 72 hours. Any delay of surgery for more than 72 hours causes a significant increase in complications.

Conditions that need a more time-consuming medical stabilization before surgery are “active” geriatric-medical conditions:

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  Heart failure, acute cardiac ischemia

  
  
• 
  

  Unclear systolic ejection heart murmur, with examination, which suggests aortic stenosis

  
  
• 
  

  Acute stroke

  
  
• 
  

  Acute infection, such as pneumonia or septicemia

  
  
• 
  

  Unstable angina pectoris

  
  
• 
  

  Severe hypotension

  
  
• 
  

  Severe chronic obstructive pulmonary disease

  
  
• 
  

  Rhabdomyolysis

Anesthesia

The role of anesthetic assessment remains an area of much concern to the surgeon. The anesthesiologist looks for the patient‘s physiological age. Physiological age is more important than chronological age. The patient‘s preinjury functional capacity is evaluated, including cognitive function and daily activities. Preoperative functional capacity may be the single best predictor of the patient‘s risk of in-hospital mortality. The medication list and the preoperative preparation for surgery are also assessed. The patient is risk stratified and then a decision is made about type of anesthesia and whether to proceed as planned with surgery. Preoperative hydration and restoration of a normothermic state (36–37.5°) is essential for success.

When deciding on the type of anesthesia to be used, the anesthesiologist will consider the procedure planned and its duration, preoperative anticoagulation, possibility of delirium, and feasibility of neuraxial anesthesia. Neuraxial blockade is associated with a reduced risk of delirium, thromboembolic events, pneumonia, and bleeding complications [22]. Presence of antiplatelet agents, such as clopidogrel, may preclude use of neuraxial anesthesia. In most cases proper preoperative rehydration will reduce the risk of hypotension during surgery. Critical aortic stenosis may also preclude use of spinal anesthesia. Use of femoral nerve blockade in the lower extremity or supraclavicular blockade in the upper extremity may provide excellent anesthesia and postsurgical analgesia.

Pain treatment

Standard algorithms for pain management should not to be applied in geriatric patients because they are more vulnerable, and many systems do not work as well as in younger patients.

The provision of good pain relief for postoperative patients is generally associated with reduced cardiovascular, renal, respiratory, and gastrointestinal tract morbidity. Good pain management enhances mobilization, lowers delirium rate, and may decrease length of hospital stay. Nevertheless troublesome medications, like nonsteroidal antiinflammatory medications, should be avoided because of potential side effects of renal insufficiency and peptic ulcers. Paracetamol, morphine, metamizol, and piritramid are used as first-line therapy intravenously and soon changed to orally administered paracetamol, metamizol, oxycodone, or hydromorphone. When using morphine, laxatives should be prescribed regularly. In addition, formal assessment and charting of pain scores helps with pain management.

There is evidence that local catheters and blocks with continuous administration of local anesthetics (3-in-1 femoral nerve block, installed with the help of sonography) are helpful to provide good pain treatment and mean that administration of additional analgesics with potentially negative side effects specifically in this patient population can be reduced [ 30, 31].

Other issues:

• 
  

  Many geriatric patients tend to have renal dysfunction; therefore routine administration of nonsteroidal antiinflammatories (NSAIDs) is not justified.

  
  
• 
  

  Elderly patients, specifically with dementia, are not able to articulate pain sufficiently; consequently, they are often not given enough analgesics. Unrecognized or undertreated pain on the other hand predisposes the development of delirium, and limits mobilization which leads to an increased morbidity.

  
  
• 
  

  An early change to oral administration of analgesics is preferred and helps to avoid delirium.

A regular formal charting of pain scores in the patient‘s medical chart should be adopted as routine practice. It helps to address pain therapy specifically and prevents undertreatment, which is common in these patients [ 32]. Furthermore, an adapted pain-therapy protocol should be used.

The following recommendations are offered:

• 
  

  Intravenous (IV) pain therapy directly postoperatively

  
  
  
  
  • 
    

    Paracetamol/acetaminophen 1,000 mg 3–4 times daily (first choice). Possibly adapt to body weight 15 mg/kg

    
    
  • 
    

    Metamizole 1,000 mg up to 3 times daily, additionally if needed

  
  
• 
  

  Piritramide 3.75–7.5 mg subcutaneously (sc) or morphine 2.5–5 mg sc (or IV) in acute pain

  
  
• 
  

  Morphine 1–2 mg intravenously every 2 hours as needed for pain

  
  
• 
  

  Early switch to oral pain medication postoperatively:

  
  
  
  
  • 
    

    Paracetamol/acetaminophen 500 mg 3–4 times daily (first choice)

    
    
  • 
    

    Metamizole 500 mg 3–4 times daily postoperatively, additionally if needed

    
    
  • 
    

    Hydromorphone 2–4 mg postoperatively or piritramide 3.75–7.5 mg sc in acute pain

Oxycodone 5 mg orally every 3 hours as needed for pain

• 
  

  On constant demand for opiate analgesics:

  
  
  
  
  • 
    

    Haloperidol 0.5mg daily to prevent nausea

    
    
  • 
    

    Macrogol for regulation of bowel movements

Opioids should only be used in low dosages first, specifically in patients at risk of delirium. When patients are cachectic or sarcopenic, dosages should be generally reduced, which is also true for patients with reduced renal function.

Metamizole is not approved in some countries, like the United States or Sweden, because of a certain risk of agranulocytosis. The drug has low rates of adverse effects and high pain-killing potential. Oxycodone is a satisfactory alternative medication.

Fluid and electrolyte balance

Electrolyte imbalance, especially hypokalemia and hyponatremia, are common in the postoperative period and reflect the limited reserves of the patients [ 33]. This situation may worsen with diuretics and inappropriate IV fluid application and can also encourage delirium. Therefore isotonic fluids should be used exclusively and electrolyte management should be monitored regularly and adjusted appropriately.

Prophylaxis with antibiotics

Gillespie et al [ 34] reported (8,307 patients) that a single-dose prophylaxis significantly reduces superficial and deep wound infections, and urinary and respiratory tract infections, whereas multiple-dose prophylaxis did not show an effect on urinary and respiratory tract infections. Thus prophylactic antibiotics should be given preoperatively and in case of verified infection. Prolonged antibiotic use is of no proven benefit for prophylaxis of wound or visceral infections.

The following recommendations may be given:

• 
  

  First- or second-generation cephalosporins are first choice

  
  
• 
  

  Single-dose cephalosporin 2 grams or vancomycin 1 gram in surgical fracture fixation

  
  
• 
  

  24 hours prophylaxis (2–3 times) cephalosporin or vancomycin in arthroplasties

  
  
• 
  

  48 hours prophylaxis (3 times/day): open fractures until smear test is sterile

  
  
• 
  

  Bedridden patients from nursing homes should be tested preoperatively with a smear test from the nose for methicillin-resistant Staphylococcus aureus (MRSA). The result is available within 24 hours. If positive, perioperative antibiotic therapy with vancomycin is indicated

Anticoagulation and thromboprophylaxis

Perioperative thromboprophylaxis should be a routine aspect in the care of geriatric fracture patients. Commonly, low-molecular-weight heparins are used. Mechanical devices may be reserved for patients with contraindications for anticoagulants and antiplatelet agents [ 35]. Many older patients are chronically anticoagulated. Warfarin is typically reversed to safely permit surgery. Postoperatively, patients using oral warfarin on admission to hospital are restarted on warfarin the day of surgery and may require perioperative “bridging therapy” with low-molecular-weight heparin or unfractionated heparin depending on the individual indication for anticoagulation therapy [35].

Venous thromboembolism is one of the leading reasons for postoperative morbidity and mortality in patients with hip fracture or other immobilizing fracture. Up to 7.5% of all patients with hip fracture sustain fatal pulmonary embolism within 3 months postoperatively.

• 
  

  Administration of thromboprophylaxis on admission depends on timing of surgery, type of anesthesia, and preexisting anticoagulation.

  
  
• 
  

  If the time between admission and surgery exceeds 2–3 hours, thromboprophylaxis with unfractionated heparin (5,000 units subcutaneously) should be started preoperatively.

In cases of preexisting anticoagulation or antithrombotic therapy or if thromboprophylaxis has been initiated preoperatively, certain therapy interruptions have to be respected if the use of regional anesthetic procedures is planned [35].

Related posts:

Humerus, proximal Humerus, shaft—introduction Humerus, shaft: wedge fracture, bending wedge—12-B2 Femur, shaft: wedge fracture, fragmented wedge—32-B3 Tibia and fibula, distal Tibia and fibula, distal—introduction

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