What to do about comorbid conditions that may affect outcomes

Terry Stanton

Medical clearance—an assessment of a patient’s fitness for surgery—is often a standard request. But a simple clearance may not uncover all of the influences on orthopaedic outcomes, as the faculty for an Instructional Course Lecture session at the Annual Meeting outlined. Obesity and its related conditions, as well as systemic issues such as renal or cardiovascular condition, are among the factors that may affect orthopaedic surgery outcomes. (See “Issues in Medical Clearance:

Thorough Assessment, Patient “Activation” Can Improve Outcomes,” Daily Edition AAOS Now, March 25, 2015.)

Other aspects often overlooked during a standard “medical clearance” include nutritional and endocrine issues and preoperative factors to optimize against periprosthetic joint infection (PJI). These topics were covered by Joseph M. Lane, MD, of the Hospital for Special Surgery, and Javad Parvizi, MD, FRCS, of the Rothman Institute.

The value of D
Dr. Lane began with an explanation of the role of vitamin D in patient health. He noted that vitamin D occurs in two forms, depending on origin: D3 (animal) and D2 (vegetable). Both are available for patient supplementation. “Although some controversy exists, the D3 form may have greater activity, longer activity, and a better profile than the D2 form,” he said.

Vitamin D has multiple activities throughout the body, but its function in bone mineralization and muscle strength holds special interest for orthopaedists. After forming in the skin and being processed in the liver and kidneys, vitamin D directly enhances mineralization of bone and enables calcium to be absorbed in the intestine. “This also appears to facilitate muscle strength,” Dr. Lane said.

Clinically, vitamin D status is measured by determining the levels of 25-hydroxyvitamin D (25[OH]D). Values below 20 ng/mL are considered deficient; for orthopaedic patients, levels should be above 30 ng/mL.

Dr. Lane referenced a study of nonunions that found vitamin D deficiency to be the most common problem after poor mechanics and osteomyelitis. “Because most examinations of patients undergoing an orthopaedic procedure have found low vitamin D levels,” he advised, “it is prudent to assume that the patient has low vitamin D and to initiate supplementation of 2,000 units per day.”

Controlling fracture risk
Turning to osteoporosis, Dr. Lane noted that low-energy fractures double the risk of a hip fracture and increase the risk for a second vertebral fracture fivefold. “Consequently any patient with a history of osteoporosis or a fragility fracture should have the bone status evaluated and treated,” he said. Critical laboratory tests include the 25(OH)D and screening chemistry profile including calcium and albumin, intact parathyroid hormone (PTH), a complete blood count, and urinary calcium.

He recommended that patients take calcium citrate (1,000 mg per day) concurrently with vitamin D supplementation. “A patient with a low-energy fracture or a bone density test with one site demonstrating 2.0 or lower bone mass should be considered for drug intervention,” he said, explaining that anticatabolic agents that prevent further bone loss include the diphosphonates, denosumab, and selective estrogen receptor modulators (SERMS). Anabolic agents that generate more bone mass and enhance bone healing and fusion include PTH 1-34 (teriparatide).

Clinical studies have demonstrated that in the best of referral situations, only 25 percent of patients with a hip fracture will ever be treated for underlying osteoporosis, Dr. Lane said. “Consequently, there is a new movement for a ‘fracture liaison service’ to assume responsibility at the time of the fracture and actually initiate full therapy.” In one study, the use of such a service increased the rate of treatment from 25 percent to 55 percent.

Dr. Lane noted that patients with type 1 diabetes patients produce inadequate amounts of insulin and those with type 2 diabetes have issues with the receptor site, while often having normal insulin levels. Both groups have higher fracture rates, poorer tissue and bone healing, and increased risks of infections compared to patients without diabetes.

The hemoglobin A1C (HbA1C) test measures glucose control; values of 6.5 or less indicate excellent control while those from 7 to 9 indicate elevated risk but should not lead to a delay in surgery. A value 10 or above “suggests poor control and elective surgery should be delayed until better control is achieved by an endocrinologist,” Dr. Lane said. “Surgical procedures should be planned according to the diabetes control, recognizing that healing is delayed.”

PJI risks and prevention strategies
Addressing issues with prosthetic joints and the risk of infection even in the absence of commonly recognized risk factors, Dr. Parvizi said that a number of medical conditions impose a “considerable risk” but “are usually inadequately addressed prior to total joint arthroplasty (TJA).”

Anemia is one condition that may lead to infection. “Systematic screening for anemia and correction of its modifiable causes via supplementation with iron, folic acid, and erythropoietin is recommended,” Dr. Parvizi said. “Patients may not adequately respond to erythropoietin therapy due to iron deficiency, and simultaneous treatment might be required.”

Malnutrition should also be addressed. “Patients should undergo a thorough nutritional check-up and be provided with adequate protein, calorie, vitamins, and mineral supplementation before elective arthroplasty,” he said. “Malnutrition impedes protein synthesis, interferes with normal immune system function, and results in a number of perioperative adverse events that potentially increase the risk of PJI, including delayed healing of the surgical wound, persistent drainage, and prolonged anesthesia time and hospital stay.”

Patients who are morbidly obese (body mass index [BMI] >40 kg/m²) should be encouraged to decrease their BMI to below 35 kg/m² before undergoing TJA. “Associated conditions—including ischemic heart disease, hypertension, hypercholesterolemia, nutritional deficiencies, diabetes or a constellation of these conditions in the form of metabolic syndrome—have been blamed for significant morbidity and mortality following TJA in these patients,” Dr. Parvizi said.

Patients with inflammatory rheumatoid disorders are at increased risk of PJI due to either the pathophysiologic changes associated with the disease itself or immunosuppressive medications that are used for its treatment. Dr. Parvizi explained that the Canadian Rheumatology Association recommends that immunosuppressive medications be stopped 3 to 5 times the half-life of each individual medication prior to surgery. Cessation of these medications should be based on individualized plans and supervised by the treating rheumatologist.

Hyperglycemia with or without diabetes is a recognized risk factor for suboptimal perioperative outcomes including PJI. “The link between hyperglycemia and susceptibility to infection has been well established,” he noted. “Although optimal glycemic control has yet to be defined, surgeons should be cautious in recommending TJA for patients with fasting glucose levels of 200 mg/L or higher or an HbA1C value higher than 7.”

Smoking is a known risk factor, and cessation as early as 6 to 8 weeks prior to surgery has been shown to decrease risk of perioperative complications. Alcohol abuse is associated with increased risk of both infectious and noninfectious postoperative complications. “A period of at least 4 weeks of abstinence has been suggested to be necessary to reverse pathophysiologic changes that increase the risk of post surgical morbidity in alcohol consumers,” he said.

Patients with deficient immunity due to underlying disorders such as metastatic cancer or immunosuppressive medications (corticosteroids, cytostatics, immunophillins, and immunosuppressive antibodies) are also at increased risk of PJI. “Although HIV infection is considered as a risk factor for PJI, HIV-infected patients with CD4 counts greater than 400 and undetected viral load are considered as appropriate candidates for TJA.”

Although poor oral health may present risks, Dr. Parvizi does not believe that routine screening for and treatment of dental disorders is justified for patients undergoing TJA. “However, severely poor dental hygiene and ongoing oral infections should adequately be treated before TJA, since they can serve as potential harbor of bacteria for later hematogenous PJIs.”

Finally, he noted that all patients should be asked about urinary symptoms during their preoperative evaluation, although elderly patients might not present classic symptoms of urinary tract infection (UTI). “Preoperative screening with urine analysis and culture is routinely recommended only for patients with recent or recurrent symptoms of UTIs. The decision to proceed or postpone surgery should be based on symptoms and colony counts,” he said. Surgery should be postponed in symptomatic patients with colony counts greater than 103/mL.

“Patients should ideally undergo TJA in their optimal status of health and be encouraged to do their best in maintaining such status after the operation,” concluded Dr. Parvizi.

The presenters’ disclosure information, including potential conflicts of interest, can be viewed at www.aaos.org/disclosure

Terry Stanton is a senior science writer for AAOS Now. He can be reached at tstanton@aaos.org

Bottom Line

• A simple medical clearance may not uncover all of the influences on orthopaedic surgery outcomes.
• As many systemic, nutritional, and endocrine issues as possible should be addressed prior to surgery.
• Patients who sustain a low-energy fracture should be assessed for osteoporosis and receive treatment, if necessary, to reduce the risk of their sustaining a second fracture.
• Steps to reduce the risk of periprosthetic joint infection—including addressing conditions such as anemia and malnutrition—should be taken.

Additional Information:
The international consensus statement on periprosthetic joint infection (PDF)