Clinical outcomes of fast-track total knee arthroplasty for patients aged >80 years.

INTRODUCTION: Because of the ageing population in Hong Kong, there is an increasing incidence of total knee arthroplasties (TKA) conducted in patients aged >80 years. METHODS: This retrospective case-control study enrolled all patients who were aged >80 years and underwent fast-track primary TKA between 2011 and 2015. Their outcomes were compared with the outcomes of a matched control group of younger patients who underwent fast-track TKA in the same period. RESULTS: In total, 220 patients were included in this study with a follow-up period of at least 2 years (mean=3.2 years; range, 2-5 years); 112 (51%) were octogenarians and 108 (49%) were non-octogenarians. Greater improvement in Knee Society Score was found in the octogenarian group at 1 year after surgery (46 ± 19 vs 39 ± 16, P=0.018). The incidence of complications was higher in the octogenarian group (15.2% vs 4.6%, P=0.009). There were no significant differences in the incidence of major complications, the rate of intensive care unit admission, or the 1-year mortality rate between the two groups. After adjustment for confounding factors, Charlson Comorbidity Index >5, history of major cerebrovascular accident, and history of peptic ulcer disease were predictive of complications after fast-track TKA (P=0.039, P=0.016, and P=0.007, respectively); octogenarian status was not predictive of complications. CONCLUSIONS: Octogenarians had greater improvement in Knee Society Score at 1 year after fast-track TKA, compared with non-octogenarians, but there were no significant differences in the incidences of mortality or major complications.

Identification of antinodes and zero-surface-strain contours of flexural vibration with time-averaged speckle pattern shearing interferometry.

A new time-averaged frame subtraction technique is introduced for vibration analysis by digital speckle shearing interferometry. The technique permits the enhancement of fringes by subtracting two Bessel fringe patterns at different forcing levels. Compared with the phase-shift method, this method is more efficient and easier to implement for qualitative vibration measurement, providing a means for fast inspection of plate vibration behavior. It is also capable of tracing contours of zero strain and locating antinodes on vibrating plates.