Improvements in Objectively Measured Activity Behaviors Do Not Correlate With Improvements in Patient-Reported Outcome Measures Following Total Knee Arthroplasty.

BACKGROUND: Activity monitors have added a new dimension to our ability to objectively measure physical activity in patients undergoing total knee arthroplasty (TKA). The aim of the study is to assess whether changes in the time spent sitting, standing, and stepping were associated with changes in patient-reported outcome measures (PROMs) before and after TKA. METHODS: Valid activPAL data (>3 days) and PROMs were obtained from 49 men and women (mean [SD] age, 62.8 [8.6] years; body mass index, 33.8 [7.1] kg/m2) who underwent primary TKA, before and at 6 weeks or 6 months after surgery. Patient-reported symptoms of pain, stiffness, and knee function were obtained using the Knee injury and Osteoarthritis Outcome Score and Oxford Knee Score questionnaires. RESULTS: Mean (SD) Knee injury and Osteoarthritis Outcome Score (80.1 [16.3] to 41.6 [6.5], P < .001) and Oxford Knee Score (12.0 [9.8] to 17.7 [22.8], P < .001) scores improved 6 months after TKA. Walking time (mean [95% confidence interval]; min/d) increased from before (79 [67-91]) to 6 months after TKA (101 [88-114], P = .006). Standing time (318 [276-360] to 321 [291-352], P = .782) and sitting time (545 [491-599] to 509.0 [459.7-558.3], P = .285) did not change from before to 6 months after TKA. Participants took more steps (2559 [2128-2991] to 3515 [2983-4048] steps/day, P = .001) and accumulated more steps (31 [30-34] to 34 [33-35] steps/min, P < .001) after TKA compared to before. There were no associations between changes in activity behaviors and changes in PROMs (P > .05). CONCLUSION: Despite improvements in self-reported knee pain and functional ability, these changes do not correlate with improvements in objectively measured light-intensity and sedentary activity behaviors.

A prospective randomized clinical trial comparing tibial baseplate fixation with or without screws in total knee arthroplasty: a radiographic evaluation.

In a randomized prospective study, we compared the use of tibial screws with screwless tibial baseplate fixation in uncemented total knee arthroplasty and report the results of 154 prostheses at a mean follow-up of 5 years. Patients were mobilized within 24 hours and continued with partial weight-bearing for up to 6 weeks postoperatively. There were no significant differences in radiologic results and revision rates. Radiographic outcomes do not seem to be influenced by the use of screws in tibial baseplate fixation of this prosthesis. The prosthesis studied has a large tibial keel and 4 adjunctive pegs that seem to provide adequate stability and allow bony ingrowth to take place. Longer follow-up will determine whether in this implant design, the use of tibial screws for cementless tibial baseplate fixation can be justified.