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ARTHROPLASTY: Metabolic syndrome raises clot risk after knee replacement

April 07, 2009 | Andrew Skelly

From the American Academy of Orthopaedic Surgeons and the Knee Society/American Association of Hip and Knee Surgeons meetings

Condition’s implications just starting to be discussed in orthopedics

LAS VEGAS | Patients with metabolic syndrome are three times more likely to suffer a symptomatic deep vein thrombosis (DVT) after total knee replacement than those who don’t have the condition, according to a Canadian study.

Metabolic syndrome is a group of cardiovascular risk factors including abdominal obesity, elevated fasting glucose, hypertension, high triglycerides and low HDL cholesterol.

In their poster, Dr. Rajiv Gandhi and colleagues at Toronto Western Hospital noted metabolic syndrome is known to be associated with a systemic prothrombotic state, but no one had looked at DVT risk in these patients after knee replacement before.

Risk stratification

The eventual goal, Dr. Gandhi told the Medical Post, is to risk-stratify patients so that DVT prophylaxis can be individually tailored, and so patients can be better informed about the risks of surgery. “We treat everyone with the same prophylactic regimen, and to me it just doesn’t make sense.”



The researchers reviewed the records of 1,460 patients who had a primary unilateral knee replacement between 1998 and 2006. All patients received a standard protocol for DVT prophylaxis—14 days of low molecular weight heparin started on the first postoperative day—and were encouraged to ambulate on the first post-operative day.

The overall incidence of symptomatic DVT within the first three months after knee replacement surgery was 4.5%.

However, the incidence was 15.5% in the 135 patients with metabolic syndrome, compared with 3.4% in the 1,325 patients without the syndrome.

Risk tripled

After adjusting for age, gender, body mass index, comorbidities and education, the researchers calculated that patients with metabolic syndrome had 3.2 times the risk of developing a DVT after knee replacement surgery.

The study was not large enough to analyze the much rarer outcome of pulmonary embolism, which had an overall incidence of less than 1%.

“In the medical literature, metabolic syndrome has been discussed for many years, but it’s something that’s just making its way into the orthopedic world,” Dr. Gandhi said. “I think it’s going to have important implications for many things, including the pathogenesis of osteoarthritis.”

Source: http://www.medicalpost.com/therapeutics/orthopedics/article.jsp?content=20090407_115250_1392

March 27, 2007 | Andrew Skelly

From the American Academy of Orthopedic Surgeons annual meeting held in San Diego. Feb. 14 to 18, 2007

Procedure may top standard of plates, screws

SAN DIEGO | Elderly patients who fracture an elbow are better off getting the joint replaced than having the fragments fixed with plates and screws, a Canadian randomized trial has shown.

The results indicated total elbow arthroplasty(TEA)produced better functional outcomes than open reduction and internal fixation(ORIF)based on both objective elbow performance scores and patient-rated disability and symptoms.

“Distal humeral fractures have plagued orthopedic surgeons over the years,” Dr. Christian Veillette, the study co-author, said in an interview at the meeting. “It’s a very difficult fracture to manage because of the complexity of the elbow. … We have a hard time getting these patients back to their(pre-fracture)level of function.”

But performing TEA instead of ORIF could improve those odds. “In the elbow replacement group they had much better range of motion and were able to do daily activities, such as doing their hair or putting on makeup, where they wouldn’t be able to do them with actually fixing the elbow.”

The study, he said, has “certainly changed our management of this patient group. … We’re much more likely to do an elbow replacement than we were in the past.”

However, he added ORIF remains the gold standard for patients younger than 65, in whom TEA wear rates would be unacceptably high due to greater activity levels.

Dr. Veillette, a clinical fellow in the department of orthopedic surgery at the Mayo Clinic in Rochester, Minn., worked on the study during a previous fellowship at St. Michael’s Hospital in Toronto.

The trial involved 42 patients age 65 or older with a displaced intra-articular fracture of the distal humerus, operated on by three surgeons at three Canadian teaching hospitals.

Twenty-one patients were randomized to each treatment group; however, one patient in each arm died prior to followup and five patients randomized to ORIF were converted to TEA intraoperatively because stable fixation was not feasible. This resulted in 15 patients(three male, 12 female, average age 77)in the ORIF group and 25 patients(two male, 23 female, average age 78)in the TEA group.

The TEA prosthesis consisted of metal components cemented to the humerus and ulna and connected by a locking pin.

The Mayo Elbow Performance Score was significantly better at three months, six months, 12 months and two years in patients who had TEA compared with those who underwent ORIF. Distribution of scores at two years was also significantly better, with 12 excellent, nine good, three fair and one poor outcome in the TEA group, compared with one excellent, seven good, six fair and one poor outcome among ORIF patients.

The patient-centred Disabilities of the Arm, Shoulder and Hand scores were significantly better with TEA than with ORIF between six weeks and six months but not at 12 months and two years, suggesting patients accommodate to limitations in function with time.

Reoperation rates were not statistically different(three of 25 for TEA and four of 15 for ORIF), but if the five patients who were converted from ORIF to TEA intraoperatively were considered to have failed treatment and required reoperation, the reoperation rate would be 45% in the ORIF group(nine of 20)and 15%(three of 20)in the TEA group, a statistically significant difference.

Eight ORIF and 10 TEA patients had at least one complication, such as ulnar nerve symptoms, wound healing problems or stiffness.

The study was funded by the Orthopedic Trauma Association and by Zimmer Inc., the maker of the TEA implant.

Source: http://www.medicalpost.com/medicine/meeting/article.jsp?content=20070327_102434_5372