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Background: Early quadriceps muscle strength assessment after a total knee arthroplasty (TKA) provides timely information on progress, but little is known about the pain profile and predictive validity associated with common clinical muscle strength tests. This study aimed to, in patients with a recent TKA, examine the associations of isometric and isotonic quadriceps strength with gait speed, accounting for knee pain experienced during testing., Methods: A sample of 76 patients (mean age 68 years; 46 women) with a recent TKA (median, 1.5 months) participated. Quadriceps strength was measured on both limbs using a knee extension machine. Isotonic strength was assessed with a one-repetition maximum test. Isometric strength was measured at 40° and 70° of knee flexion using a custom-built load cell. To allow for valid comparisons between the tests, quadriceps strength symmetry ratios were calculated. Knee pain during testing was measured using an 11-point pain scale. Fast gait speed was measured using the 10-m walk test., Results: Compared with isotonic test, quadriceps strength ratio was higher for the 40° flexion isometric test (P = 0.01), and this difference may be explained by the lower knee pain intensity elicited during the isometric tests (P's < 0.001). All strength measures were closely associated with fast gait speed after adjustment for knee pain and covariates (P's < 0.001)., Conclusions: Early in the post-TKA period, isometric and isotonic strength tests may be used to assess quadriceps strength but these tests are not interchangeable. Isometric quadriceps testing may be preferable to isotonic testing as it was associated with lower knee pain intensity., (Copyright © 2018. Published by Elsevier Ltd.)

According to their solubility parameters, retinol and its derivatives, as well as cholesterol and other lipophilic substances, are predicted to dissolve in intraocular silicone and fluorosilicone oils. Calf retinas were extracted in vitro with these oils and the oils then analyzed spectrophotometrically. The following levels were found after extraction for 4 and 48 hours, respectively: for retinol, silicone oil, 0.5 and 3.7 micrograms/ml, and fluorosilicone oil, 0.5 and 3.3 micrograms/ml; for cholesterol, silicone oil, 0.5 and 6.4 micrograms/ml, and fluorosilicone oil, 0.8 and 3.7 micrograms/ml. In in vivo experiments, intraocular oils were removed from rabbit eyes at 4 days to 10 weeks after injection. The retinol levels were 1.7 to 11.4 micrograms/ml in silicone oil and 2.4 to 7.3 micrograms/ml in fluorosilicone oil; the cholesterol levels were 2.7 to 12.6 micrograms/ml in silicone oil and 7.5 to 15.6 micrograms/ml in fluorosilicone oil. Fluorosilicone and silicone oils (1000 cs) removed from human eyes at 7.3 and 102.0 weeks postoperatively had a retinol content of 5.4 and 2.9 micrograms/ml, respectively. Silicone oil of 1000 cs removed from a patient 51 weeks postoperatively and silicone oil of 12,500 cs removed 96 weeks postoperatively gave reaction characteristics for cholesterol, 230 and 99 micrograms/ml, respectively.