Cartilage survival of the knee strongly depends on malalignment: a survival analysis from the Osteoarthritis Initiative (OAI).

PURPOSE: Progression of osteoarthritis over time is poorly understood. The aim of the current study was to establish a timeline of "cartilage survival rate" per subregion of the knee in relation to mechanical alignment of the lower extremity. The study hypothesized that there are differences in progression of osteoarthritis between varus, valgus and physiologic lower extremity alignment. METHODS: Based on hip-knee-ankle standing radiographs at baseline, 234 knees had physiologic (180° ± 3°, mean 179.7°), 158 knees had varus (< 177°; mean 174.5°) and 66 knees valgus (> 183°; mean 185.2°) alignment (consecutive knees of the OAI "Index Knee" group, n = 458; mean age 61.7; 264 females). The Osteoarthritis Initiative (OAI; a multi-center, longitudinal, prospective observational study of knee osteoarthritis [30] using MRIs) defines progressive OA as a mean decrease of cartilage thickness of 136 µm/year and a mean decrease of cartilage volume by 5% over 1 year (DESS sequences, MRI). A Kaplan-Meier curve was generated for osteoarthritis progression based on OAI criteria. RESULTS: Osteoarthritis progression based on volume decrease of 5% in varus knees occurred after 30.8 months (medial femoral condyle), after 37 months (medial tibia), after 42.9 months (lateral femoral condyle) and 43.4 months (lateral tibia), respectively. In a valgus alignment progression was detectable after 31.5 months (lateral tibia), after 36.2 months (lateral femoral condyle), after 40.4 months (medial femoral condyle) and 43.8 months (medial tibia), respectively. The physiological alignment shows a progression after 37.8 months (medial femoral condyle), after 41.6 months (lateral tibia), after 41.7 months (medial tibia) and after 43 months (lateral femoral condyle), respectively. CONCLUSION: Based on data from the OAI, the rate and location (subregion) of osteoarthritis progression of the knee is strongly associated with lower extremity mechanical alignment. LEVEL OF EVIDENCE: Level I (prognostic study).

Predictive values of WOMAC, KOOS, and SF-12 score for knee arthroplasty: data from the OAI.

PURPOSE: A number of validated scores are available to monitor clinical outcome after knee arthroplasty. The current study examines whether WOMAC, KOOS, or SF-12 scores have a predictive value to identify patients that require total knee arthroplasty within 1 year. METHODS: The Osteoarthritis Initiative includes 4684 patients in two groups: incidence subcohort (Group A, n = 3284) and progression subcohort (Group B, n = 1400). A total of 278 patients reached the endpoint "unilateral knee replacement" (Group A = 96; Group B = 182). WOMAC, KOOS, and SF-12 scores at the maximum of 12 months prior to surgery were used to analyse predictive values. ROC analysis and the diagnostic accuracy for these scores were reported. RESULTS: Group A: WOMAC and KOOS score as well as the "physical component summary" of SF-12 showed an area under the curve (AUC) between 0.8 and 0.9 (high diagnostic evidence) to predict total knee replacement. The KOOS "symptoms" (0.67) and SF12 "function" (0.79) showed lower values. The KOOS QoL score showed the highest predictive value with an AUC of 0.84 (CI 95% 0.77-0.91, p < 0.001) resulting in a sensitivity of 0.88 and a specificity of 0.72. Similar numbers were achieved by the total WOMAC score with an AUC of 0.85 (CI 95% 0.82-0.88, p < 0.001) resulting in a sensitivity of 0.77 and a specificity of 0.82. The SF-12 physical component score had an AUC of 0.83 (CI 95% 0.79-0.87, p < 0.001) resulting in a sensitivity of 0.87 and a specificity of 0.68. Different combinations of scores increase the positive likelihood ratio (up to 18) and specificity (up to 0.97). Group B scores showed lower AUCs, sensitivities and specificities. CONCLUSIONS: Combinations of WOMAC, KOOS, or SF-12 scores accurately predict patients that require knee arthroplasty within 1 year. In addition to other clinical parameters (physical examination, radiographs), they can guide patient and surgeon during the treatment of arthritis of the knee. LEVEL OF EVIDENCE: II.

Acute pseudophakic pupillary block glaucoma.

Intraocular lenses are becoming increasingly common, yet many emergency physicians are unaware of their potential complications. The case of a 59-year-old man whose anterior chamber lens occluded the pupil, resulting in acute glaucoma with an intraocular pressure exceeding 65 mm Hg, is presented. He was treated successfully with medical therapy and laser iridotomy. A review of this condition, treatment, and prognosis is presented. The emergency treatment of pupillary block glaucoma differs from that of "classic" acute closed-angle glaucoma.

Atropine absorption after intramuscular administration with 2-pralidoxime chloride by two automatic injector devices.

Compared with manual intramuscular injection, automatic injector delivery substantially enhances drug absorption rate. We examined the effect of two types of automatic injector delivery of two drugs which are components of the standard antidote to anticholinesterase poisoning and which have been previously shown to have a reduced absorption rate when mixed together in a manual injection. In crossover experiments one week apart, 20 nonsmoking healthy young male humans (ages 20-30) were studied after citrated atropine (6.9 mumol/0.7 mL) and pralidoxime chloride (3.5 mmol/2.0 mL; PAMCL) were injected sequentially into a single intramuscular site by either a multichambered autoinjector or a device which delivers the drugs into two separate intramuscular sites (MARK I). Atropine absorption was assessed by the appearance of atropine in the serum and by changes in heart rate, salivary secretion, pupil diameters, and near vision accommodation. Atropine absorption was significantly greater in the first 30 min following injection with the MARK I. The results of this study suggest that: (1) the MARK I device produces a faster absorption of atropine, probably through some combination of its broader dispersal of atropine in the muscle site and its separation of atropine from the PAMCL; (2) salivary secretion may be the most convenient and sensitive marker of atropine action; and (3) the 6.9- mumol (2-mg) dose of atropine delivered by either autoinjector gives near maximal antisialogogue activity in normal male humans.

Effect of eye color on heart rate response to intramuscular administration of atropine.

Melanin has been previously shown to modify the mydriatic response to atropine instillation. Skin and iris pigmentation has also been shown to modify aspects of the heart rate response to injected atropine, although these observations have been generally overlooked. In this study, 20 healthy non-smoker male subjects, ages 20-30 years, were injected by two different automatic injector devices and the mydriatic and heart rate responses in the first 90 min were reported. The group included 8 brown-eyed, 4 hazel-eyed, and 8 blue-eyed subjects. Although there were differences in the rate of atropine delivery between the two injection devices, the heart rate responses were independently modified by eye color to a magnitude of difference as great as the differences between injectors. Subjects with more pigmented irides (brown-eyed) showed a more rapid rise in heart rate compared to less pigmented irides (hazel-eyed and blue-eyed subjects). Following injection by the device with a slower atropine absorption rate, these differences were particularly enhanced and an abbreviated bradycardic phase of the heart rate response was observed for the brown-eyed subjects. This observation confirms earlier reports and suggests the possibility of an interference by melanin (in the iris or elsewhere) in atropine accessibility to selected muscarinic target sites.