Keeping you up to date on recent headlines in orthopedic healthcare:

Is a gender-specific design necessary? .... "Specific anatomic differences are thought to account for gender-specific outcomes after total knee arthroplasty (TKA); however, using prospectively collected data, our study found that females had higher early improvement in function and pain scores after unisex TKA than males," said Thoralf Liebs, MD, the lead author of a paper that was presented at the American Association of Orthopedic Surgeons (AAOS; Rosemont, Illinois) annual meeting. Liebs noted that because the findings suggest that women benefit from TKA to a higher degree than men, regardless of the type of implant, the need for female-specific implant designs is not substantiated.Researchers collected data on patients diagnosed with osteoarthritis who were scheduled to undergo unilateral hip or knee replacement surgery at five participating centers in Germany between Jan. 1, 2003, and April 30, 2006. Patients enrolled in the trial were asked to complete a questionnaire on comorbidities at time of admission to the hospital. Investigators did not find any statistically significant differences between the sexes regarding body mass index (BMI) or the number of comorbidities and additional limitations. Females, however, had significantly lower mean scores on the mental component summary of the SF-36. The rationale for gender-specific TKA design, noted Liebs, is based on specific anatomic differences and the assumption that outcomes for women are inferior following TKA using a unisex implant. Liebs pointed out that the failure of the study to identify statistically significant differences in the raw outcomes between the sexes after knee arthroplasty raises the question of whether the WOMAC as an outcome measure is just not sensitive enough to capture the differences in postoperative outcomes. "It remains to be demonstrated whether gender-specific TKA designs reveal improved raw outcome scores when compared among females," said Liebs.

Vegan, non-vegetarian women found to have identical bone density .... A study comparing the bone health of 105 post-menopausal vegan Buddhist nuns and 105 non-vegetarian women, matched in every other physical respect, has produced a surprising result. Their bone density was identical. The study was led by Professor Tuan Nguyen from the Garvan Institute of Medical Research (Sydney, Australia). He collaborated with Ho-Pham Thuc Lan, MD, from the Pham Ngoc Thach Medical University (Ho Chi Minh City, Vietnam). Their findings are now published online in Osteoporosis International. "For the 5% of people in Western countries who choose to be vegetarians, this is very good news," said Professor Nguyen. "Even vegans, who eat only plant-based foods, appear to have bones as healthy as everyone else. Bone health in vegetarians, particularly vegans, has been a concern for some time, because as a group they tend to have a lower protein and calcium intake than the population at large. In this work we showed that although the vegans studied do indeed have lower protein and calcium intakes, their bone density is virtually identical to that of people who eat a wide variety of foods, including animal protein." The nuns' calcium intake was very low, only about 370 mg a day, where the recommended level is 1,000 mg. Their protein intake was also very low at around 35 g a day, compared with the non-vegetarian group, which was 65 g. Nguyen and Thuc Lan chose to study Buddhist nuns because their faith requires them to observe strict vegan diets all their lives. "We didn't study vegetarians from the West because many are lacto-vegetarians, so could have considerable calcium in their diets. It would have compromised the results," Nguyen explained. "The Buddhist nuns came from 20 temples and monasteries in Ho Chi Minh City. The control group, 105 non-vegetarian women of exactly the same age, were recruited from the same localities." Source: Garvan Institute of Medical Research

Half of all musculoskeletal injuries occur in home .... More than three of every five accidental injuries that occur annually in the U.S. are to the musculoskeletal system. In 2004, more than 57.2 million musculoskeletal injuries were treated in healthcare settings and accounted for 60% of injuries of all types treated that year. Musculoskeletal injuries include sprains and strains, usually incurred during sudden movement or excessive use (16.3 million injuries in 2004); fractures (15.3 million); open wounds, cuts, and punctures (10.3 million); and contusions and bruises (8.4 million). Many more musculoskeletal injuries occur at home that are not reported. One in two musculoskeletal injuries occurs in the home, more than in any other location. About one in 10 occurs while playing in sports activities and another one in 10 in automobile or pedestrian accidents. Falls are the leading cause, 29%, of nonfatal musculoskeletal injuries. Among persons aged 65 and older, falls were the cause of 63% of nonfatal injuries treated in 2003. Workplace musculoskeletal injuries, known collectively as musculoskeletal disorders (MSDs), occur each year due to accidents and to cumulative and repetitive motion. MSDs are tracked by the U.S. Department of Labor, Bureau of Labor Statistics. MSD injuries are often more severe than the average nonfatal workplace injury or illness, with longer recovery time and an average of nine days away from work, two days longer than average for all workplace injuries.

Four out of five patients satisfied after TKR .... "Patients who are older, who have unrealistic expectations, who have comorbidities, who live alone, or who have a complication requiring hospital readmission are most likely to be dissatisfied following total knee replacement (TKR)," according to Robert Bourne, MD. Bourne presented the results of his paper, "Patient satisfaction after TKR: Who is happy and who is not?" at the AAOS annual meeting. A low preoperative score on the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) is also a factor, but a low WOMAC change score is even more predictive of patient satisfaction. "Patients who will not achieve a WOMAC change score of more than 25 out of 100 points should be operated on with caution," Bourne warned. Several studies have shown that only 82% to 89% of patients are satisfied with their TKR.

Computer-assisted TKAs yield better outcomes .... Computer-assisted navigation may result in better outcomes than standard instrumentation methods for total knee arthroplasty (TKA) patients, according to the authors. John Dillon, MRCS, presented the results of "Functional outcome assessment after navigated and standard TKA using gait analysis" at the 2009 AAOS Annual Meeting. The research team conducted a prospective, controlled study of 54 patients based on gait analysis. Standard instrumentation was used for TKA in 20 patients (9 men, 11 women; mean age 66.3 years); 20 patients (8 men, 12 women; mean age 67.2 years) had TKAs performed using a computer-assisted navigation system; and 14 patients with no history of knee pathology, knee surgery, or gait abnormality acted as controls. All patients in the two TKA groups were given the same implant. The researchers found that, while walking, TKA patients who had standard instrumentation had a longer double-stance support time (mean 17% of the gait cycle) than patients in the navigated group (mean 15.5% of the gait cycle). However, other outcome measures including biphasic moment pattern, adduction moment, and maximum flexion angle were better in patients who had computer-assisted TKA surgery. Additionally, patients who had computer-assisted TKA fared better in chair sitting and rising, stair ascent, and stair descent. Dillon pointed out that range of motion among both navigated and standard groups was lower than the control group. He also noted that the presence of a biphasic moment pattern has been shown to be a reliable finding in normal subjects, and the navigated group had a higher proportion of patients with that finding than the standard group. Compared to TKA performed using standard instrumentation, TKA performed with computer-assisted navigation achieved an overall improvement in dynamic functional knee outcomes.

— Compiled by Holland Johnson, MDD

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