This study measured the activity level before and one year after the total knee replacement surgery among Hungarian patients. To our knowledge, this is the first study in Hungary that used a high valid objective accelerometer to understand the physical activity level of Hungarian patients with severe knee OA and their physical activity improvement after one year of the TKR. The patients were asked to use the ActivPAL for six consecutive days. This study found that Hungarian patients with severe knee osteoarthritis spend most of their daily time sitting with average 18.2 ± 1.9 hours per day, and they only spend almost 1.6 ± 0.6 hours per day walking with an average of 6565 ± 2697 steps per day. After one year of the TKR, the Hungarian patients have better physical activity levels and less pain (less pain or a better QOL in general) based on both objective and subjective tools. For instance, the number of steps and the stepping time improved after one year of the surgery by 12.3% and 37.5% measured by ActivPAL. However the sitting time decreased from 18.2 ± 1.9 to 15.8 ± 3.2 hours per day, these changes are still not enough to let the Hungarian patients meet the general physical activity guideline .
Few studies evaluated the PA using the same accelerometer with a one-year follow-up [22, 23].Granat et al., 2020  evaluated the physical activity of 33 patients before and one year after the surgery. This study found that the stepping time and the number of steps improved significantly by 38.77% and 45.6%, respectively, which is similar to our findings. Moreover, Lützner et al.,2014  evaluated the physical activity level of 97 patients before and one year after the knee surgery with ActivPAL. This study found that the number of steps improved by 20.3% (from 5278 ± 2999 to 6473 ± 3654 steps/day) and no changes were seen in sitting and stepping time after one year of the surgery. However, this result could be due to applying the ActivPAL over the tibia which is a less reliable position and the monitor was used for four days.
Furthermore, this study found that the PA of Hungarian patients was improved based on the SF-36 questionnaire. The total score of the SF-36 questionnaire significantly improved by 58.3% (p = 0.041) after one year of the surgery. Similarly, among Greek elderly women, the total score of SF-36 significantly improved from 29.33 ± 11.3 before the surgery to 62.35 ± 2.7 after six months of the surgery . It seems that Hungarian patients have higher physical activity levels than Greek patients before and after the surgery. This finding could due to the very severe pain the Greek patients had before the surgery as 85% of them had continuous severe pain before the surgery . Other studies used different types of questionnaires. For instance, Granat et al., 2020  found that the physical activity based on the Oxford knee score (OKS) significantly increased by 142% (p = 0.00) after one year of the surgery. Also, the OKS score improved after six months of the surgery from 12 points to 42 points .
To sum up, the TKR is an effective intervention for Hungarian patients with severe knee osteoarthritis to reduce their pain and enhance their quality of life. However, long follow-up and staying active after the surgery are still necessary in order to get better outcomes. These findings are important for therapists who care for Hungarian patients with severe knee osteoarthritis in order to understand their physical captivity limitations before the surgery and how to improve it after the surgery.