JAAOS, Volume 18, No. 5

Computer-assisted orthopaedic surgery (CAOS) is performed by digitizing the patient's anatomy, combining the images in a computerized system, and integrating the surgical instruments into the digitized image background. This allows the surgeon to navigate the surgical instruments and the bone in an improved, virtual visual environment. CAOS in traumatology is performed with images obtained by fluoroscopy, CT, or three-dimensional fluoroscopy. CAOS is used in basic trauma procedures for preoperative planning, fracture reduction, intramedullary nailing, percutaneous screw or plate fixation, and hardware or shrapnel removal. Potential benefits of CAOS include minimal invasiveness, increased accuracy, and decreased radiation exposure. Limitations include a significant learning curve, increased surgical time, requirements for special setup and equipment handling in the operating room, specialized technical support, and cost. Current evidence shows no advantage with CAOS in trauma cases compared with conventional methods. Prospective randomized trials and clinical outcomes are lacking.

The complex structure and biomechanical function of articular cartilage make chondral injuries a management challenge. Articular cartilage has limited, if any, capacity to heal and/or regenerate. Although the natural history of articular cartilage lesions has not been clearly studied, significant injuries are believed to progress, resulting in degenerative arthritis of the joint. Changes have been made in surgical techniques in an attempt to better manage these lesions, and a large industry has been built around arthroscopic and open surgical procedures for managing cartilage repair. However, there is limited evidence that any intervention significantly alters the natural history of these lesions. Randomized trials have been done to examine the outcomes of common restoration procedures performed in the United States today, such as microfracture, osteochondral autograft transfer, and autologous chondrocyte implantation. Because the natural history of articular cartilage lesions has not been defined, we can assess the utility of surgical interventions only by comparing methods.

The overall incidence of perioperative death is relatively low. However, patients with coronary artery disease are at higher than average risk of perioperative cardiac complications. Thus, preoperative testing for cardiac disease should be done in certain patients in an effort to reduce postoperative mortality and morbidity. Patients who require emergent orthopaedic surgery are at greater risk of perioperative cardiac events than are those who undergo elective procedures. Certain modalities, such as beta blockers, statins, and alpha-2 agonists, may be started or continued in the postoperative period to further enhance cardiac function. We review the current recommendations for preoperative cardiac testing in orthopaedic patients and for perioperative management of orthopaedic patients with known cardiac disease.

Osteoporosis is an underrecognized and undertreated condition associated with fracture. More than 2 million fragility fractures occur each year, almost 300,000 of them hip fractures associated with a threefold risk for future fractures, as well as a 15% to 33% mortality rate within the first year of fracture. Orthopaedic surgeons can facilitate osteoporosis treatment by coordinating care for patients with fragility fractures by managing the current fracture, evaluating risk factors for osteoporosis, and, for hospitalized patients, developing a follow-up plan that notes whether the patient should be further evaluated or treated for osteoporosis. For the patient seen in the office, evaluation for osteoporosis should be performed and, if indicated, treatment should be undertaken. When osteoporosis treatment is warranted, diphosphonates are the standard of care, and administration of zoledronic acid once yearly has been proven to reduce the risk of subsequent fractures after low-energy hip fracture. By following these steps, orthopaedic surgeons can help ensure that patients with fragility fractures receive appropriate osteoporotic treatment, thereby reducing the risk of subsequent fractures.

Improper acetabular component orientation negatively affects the outcome of total hip arthroplasty through increasing dislocation rates, component impingement, bearing surface wear, and the number of revision surgeries. Leg length, hip biomechanics, pelvic osteolysis, and acetabular component migration are also affected by malposition. With conventional techniques, numerous variables, such as patient size, deformity and/or position, and decreased visualization, contribute to inter- and intrasurgeon acetabular component variability during surgery regardless of surgeon experience and practice volume. New acetabular component implantation techniques, such as patient-specific morphology, that incorporate anatomic landmarks may provide more accurate and individualized target zones. These techniques, coupled with the use of quantitative technology such as computer-aided navigation, may improve the precision of acetabular component placement.

Polymethylmethacrylate (PMMA) has been used in orthopaedics since the 1940s. Despite the development and popularity of new biomaterials, PMMA remains popular. Although its basic components remain the same, small proprietary and environmental changes create variations in its properties. PMMA can serve as a spacer and as a delivery vehicle for antibiotics, and it can be placed to eliminate dead space. Endogenous and exogenous variables that affect its performance include component variables, air, temperature, and handling and mixing. PMMA is used in hip arthroplasty and vertebral augmentation, notably, vertebroplasty and kyphoplasty. Cardiopulmonary complications have been reported.

For this technology overview, the tools of evidence-based medicine were used to summarize information on the indications, effectiveness, and failure rates of modern metal-on-metal hip resurfacing technology. The task was complicated by the fact that resurfacing arthroplasty is commonly offered only to a subset of patients who are candidates for total hip replacement, often prohibiting direct comparisons. Comprehensive literature searches were conducted to address four key questions addressing revision rates, patient characteristics, effectiveness of treatment, and whether improved technique, surgeon experience, and/or patient selection lead to improved outcomes. Despite data limitations, it is apparent that revision rates are higher after resurfacing than after total hip arthroplasty. Potential prognostic indicators did not yield a consistent predictor of patient-oriented outcomes (eg, pain relief) for either resurfacing arthroplasty or total hip replacement. Because of differences between patients who received hip resurfacing and those who received total hip arthroplasty, the results of studies comparing these techniques cannot be interpreted. Finally, changes in technique and increased experience result in a decrease in revision rates and femoral neck fractures and improved pain and hip scores in resurfacing.