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| Allan Gelber, M.D.
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Abstract 458 Chopstick Arthropathy. The Beijing Osteoarthritis (OA) Study Many investigations in the field of osteoarthritis epidemiology have focused on the role of joint use and levels of physical activity as a causal risk factor for this disorder. Such investigations have also examined the relationship of occupational and leisure time activities to the prevalence and incidence of osteoarthritis. In this vain, investigators in the Beijing Osteoarthritis project undertook an evaluation of the relationship of chopstick use to prevalent hand joint osteoarthritis. There were 1008 men and 1499 women, age 60 years and older, residents of Beijing, who participated in the study. The responses of the participants to questions related to chopstick use, handedness, and pincer grip activities were examined with regard to radiographic presence of hand osteoarthritis. Results: Hunter et al demonstrated that chopstick use was associated with radiographic evidence of hand osteoarthritis, in the thumb interphalangeal, 2nd and 3rd metacarpophalangeal, and 2nd and 3rd proximal interphalangeal joints. Moreover, this relationship was more pronounced among women. As a notable control, the investigators found no association between chopstick use to joints not associated with chopstick use, i.e. in the 4th and 5th fingers. Editorial Comments: From a methodologic standpoint, we are not explicitly informed as to whether the radiologists interpreting the x-rays were blinded to chopstick status. Nevertheless, these findings lend further support to the presumption that mechanical stress, through increased forces exerted upon vulnerable joints, is related to the development of osteoarthritis. | ||
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Abstract 1269 Utilization Rates and Perioperative Outcomes of Primary and Revision Total Knee Replacement in the US Medicare Population Osteoarthritis represents the leading indication for several hundreds of thousands of knee replacements performed annually in the United States. The purpose of this study was to examine the relation of demographic factors with utilization rates for total knee replacement (TKR) surgery and associated 90 day postoperative outcomes. Results: Using a Medicare claims database for the year 2000, Losina et al examined these issues and found that utilization of knee replacement surgery differed across age groups, occurring most often in the 75-79 age category. In addition, women were 40% more likely than men to undergo knee replacement. Blacks were 27% less likely than whites to have primary TKR. Similarly, those with low income (eligible for Medicaid) were less likely than those with higher income to undergo a primary TKR. Of note, complications occurred rarely in the first 90 days following primary TKR, with a mortality rate of only 0.6%. Pulmonary embolism, deep wound infection and acute myocardial infarction all occurred at a rate less than 1%. Women had lower risks of perioperative mortality, wound infection and myocardial infarction compared to men, whereas blacks had higher risk of mortality and wound infection than whites. Low-income patients were at greater risk for mortality, pulmonary embolism, wound infection and myocardial infarction. Editorial Comments: These population estimates of knee replacement utilization and postoperative outcomes, derived from a large Medicare database, reinforce the message that knee replacement surgery is a safe surgical procedure, with rare complications in the 90-day postoperative period. Those are higher risk for adverse events include men, blacks and those with low income. Further effort to better understand these demographic differences in outcome would potentially shed light on ways to improve outcomes for this most common surgical procedure. | ||
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Abstract 1071 Varus Thrust During Ambulation and the Progress ion of Knee Osteoarthritis (OA) Varus thrust is a lateral knee motion of the weight-bearing limb during ambulation that appears as a worsening of varus alignment. Varus thrust reflects dynamic malalignment, instability, and, in theory, an acute increase in medial load during ambulation. This study tested the hypothesis that varus thrust increases the risk of progression of medial knee OA, and that this effect is attenuated after adjusting for severity of varus alignment, a risk factor for, and possibly a mediator of, OA progression. Method: 230 persons with knee OA were followed for 18 months. Baseline assessments included varus thrust, alignment (on full limb x-ray), and BMI. Semi-flexed, fluoro-guided knee x-rays were obtained at baseline and at 18 months in all participants, and progression was defined as worsening of grade of medial joint space narrowing. Of the 230, 64 underwent quantitative gait analysis to determine the peak external knee adduction moment. Logistic regression with GEE was used to estimate odds ratios (OR) for medial OA progression. Results: 222 participants (401 knees) with mild to moderate knee OA were evaluated. 163 or 73% were women, mean age was 68, and mean BMI was 30). Of the 401 knees, 67 had a varus thrust. As compared to knees without a thrust, knees with a thrust were more severely varus (3.30o varus vs. 1.14o valgus, p < .0001), had a greater peak adduction moment (3.63 +/- 0.66 %body wt x ht vs. 2.60 +/- 0.81, p < .0001), and had greater loss of medial joint space over the 18 months (0.20 vs. 0.007 mm). A varus thrust was associated with a 4-fold increase in the odds of medial OA progression over 18 months (age, gender, BMI-adjusted OR 3.97, 95% CI 2.13, 7.41). As anticipated, after further adjustment for severity of varus alignment, the OR was reduced (1.76, 95% CI 0.87, 3.53). Results were not altered by adjusting for baseline disease severity, and were similar using worsening of K/L grade to define progression. Conclusions: A varus thrust at baseline increased the risk of medial OA progression. This effect is mechanistically not independent of malalignment. Those with a thrust had significantly more severe varus, and, in the substudy, a greater adduction moment. Varus thrust is a simple, cheap, and quick means of capturing varus malalignment, but as assessed in a dynamic functional activity, and without requiring any x-ray or special equipment. Further, these results introduce the possibility that intervention to stabilize these knees to prevent the malalignment that develops or worsens during ambulation may delay medial knee OA progression. Editorial Comments: During the presentation, the investigators showed a videotape of a patient with a varus thrust. The thrust was subtle and difficult for the non-practiced eye to identify. However, with proper training, assessment of thrust could presumably replace full-length alignment films for identifying varus malalignment, and serve as a prognostic factor for more rapid progression of medial compartment disease. The problem is that varus malalignment is also an outcome in knee OA &$151; that is, loss of medial joint space results in varus malalignment. So, it is conceptually difficult to implicate varus malalignment in the causal pathway when it is also an anatomical or structural reflection of disease. [This is somewhat similar to joint erosions in RA as a predictor of more joint erosions.] Nonetheless, a comprehensive understanding of the full spectrum of structural and inflammatory aspects of OA will promote a better understanding of the disease. | ||
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