Objective：The aim of this study was to examine the relationships between the timing of gait acquisition and the length of hospitalization, and to clarify the differences in background factors and functional recovery during the early postoperative period and their effect on the variability in gait acquisition.
Methods：We recruited 148 patients who underwent total knee arthroplasty (TKA) at three hospitals. The participants were divided into two groups on the basis of the number of days needed to achieve independent gait at ≤14 days after surgery (group A) and ＞14 days after surgery (group B). We compared the background factors between the two groups. Additionally, we compared the preoperative and postoperative function in each group.
Results：We observed a significant positive correlation between the number of days needed to achieve independent gait and the length of hospitalization. In group A, the significant background factors were younger age and higher preoperative activity level. In group A, compared with the level of preoperative function, the postoperative maximum knee extension angle on the operated side and pain had significantly improved. In both groups, the postoperative knee extensor strength on the operated side, knee extensor strength on the nonoperated side, knee flexion strength on the operated side, maximum knee flexion angle on the operated side, and walking speed were significantly reduced.
Conclusion：During early rehabilitation, it is necessary to consider the age and previous activities of patients. In addition, we suggest that early rehabilitation with a focus on reducing pain by alleviating inflammation and improving maximum knee extension angle on the operated side may be effective for fast acquisition of gait.

Objective：To elucidate factors associated with physical function and clarify the actual condition of functional deterioration in patients with knee osteoarthritis (OA) prior to total knee arthroplasty (TKA)．

Methods：We enrolled 467 patients with severe knee OA and preoperatively assessed the following parameters：background factors (sex, age, BMI, K-L grade, and pain) and physical function (muscle strength of knee extensors and flexors, and knee joint angles). A multiple regression analysis was performed to determine the relationship between the independent background factors and dependent physical functions. The median of preoperative function based on selected factors of physical function was calculated.

Results：Based on the multiple regression analysis, sex, BMI, K-L grade, and pain statistically significantly correlated with muscle strength of knee extensors and flexors. Sex and BMI statistically significantly correlated with knee joint flexion angle. K-L grade statistically significantly correlated with knee joint extension angle. The median of muscle strength for knee extension was 0.98/0.92 Nm/kg (Grade 3/Grade 4) for males and 0.70/0.59 Nm/kg for females. The median of muscle strength for knee flexion was 0.53/0.45 Nm/kg for males, 0.36/0.30 Nm/kg for females. The median for knee joint flexion angle was 130° for males and 120° for females. The median for knee joint extension angle was -5°/-10° (Grade 3/Grade 4)．

Conclusion：We clarified the degree of muscle strength and range of motion before TKA in patients with knee OA. We believe that the findings obtained in this study will contribute to explaining the functional deterioration of patients with knee OA.