Kennedy DM, Stratford PW, Riddle DL, et al. Assessing recovery and establishing prognosis following total knee arthroplasty.

Kennedy DM, Stratford PW, Riddle DL, et al. Assessing recovery and establishing prognosis following total knee arthroplasty. Phys Ther. 2008;88:22-32.

What problems did the researchers set out to study, and why? Current studies fail to optimally assist physical therapists with predicting the amount and rate of functional improvement for patients following total knee replacement (TKA). This study aimed to determine the pattern of change in functional status during the 1-year period following TKA and the effect of preoperative functional status on postoperative change in function.

Who participated in this study? 84 patients with knee osteoarthritis (mean age=66 years, SD=9 years) scheduled to receive TKA at a hospital in Toronto, Ontario, Canada.

What new information does this study offer? Preoperative functional status directly predicted the level of postoperative functional improvement in this study. According to models generated by the authors, the greatest rate of postoperative improvement in Lower Extremity Functional Scale (LEFS) and 6-Minute Walk Test (6MWT) scores occurred within the first 12 weeks. Although the most improvement occurred during the first 16 weeks following TKA, improvement continued, at a slower rate, between weeks 12 and 26. Little improvement was noted beyond week 26.

How did the researchers go about the study? This study was conducted between November 2001 and February 2004. Prior to TKA, LEFS and 6MWT measurements were obtained. Postoperative physical therapy was provided to subjects using a structured clinical pathway during the first week. Subjects were discharged after a maximum of 7 days of hospitalization. After discharge, they were provided with a home exercise program, with some of them also receiving formal physical therapy intervention. Subjects completed the LEFS and 6MWT at different frequencies and intervals during the 52 weeks following TKA, in order to reduce the effect of temporal bias in measurement sampling. For data analysis, subjects were divided into subgroups based on sex and preoperative functional level. Growth curves then were generated using mixed-effects nonlinear modeling in order to plot the pattern of improvement for each subgroup against time.

How might these results be applied to physical therapist practice? This study provides physical therapists with scientific evidence that can be used to help set treatment goals and prognosticate functional outcomes for their patients with TKA who resemble the study sample.

What are the limitations of the study, and what further research is needed? Application of this study's findings to patients requires physical therapists to conduct preoperative testing using the LEFS and 6MWT. Additional studies are necessary to examine the prognostic value of these measurements when taken during the postoperative period. The results of this study can be generalized only to patients fitting the demographic characteristics, surgical and physical therapy treatment, and functional tests selected by the authors. Similar methods, however, might be used to determine optimal prognostic decision making for other subgroups of patients.

TE Davenport, PT, DPT, OCS, is Assistant Professor, University of the Pacific, Stockton, Calif.