Physical activity levels after limb salvage surgery are not related to clinical scores—objective activity assessment in 22 patients after malignant bone tumor treatment with modular prostheses

Abstract

The aim of the present study was to objectively assess the physical activity levels of patients after tumor prosthesis implantation with two objective measurement devices. The DynaPort ADL monitor permitted up to 24 hr monitoring of lower-extremity physical activities in daily life with respect to posture and locomotion. The step activity monitor (SAM) was worn for a whole week to collect the daily number of gait cycles. The devices were worn during the waking hours by 22 patients with knee prostheses after wide tumor resection. In the MSTS and TESS scores the patients achieved over 80% of the maximum score indicating a good clinical outcome. The most prominent activity was sitting which accounted for 54 +/- 18% of the recorded time, followed by standing (27 +/- 16%), locomotion (10 +/- 6%), and lying (8 +/- 6%). During locomotion, the average walking activity accumulated to 4,786 +/- 1,770 step cycles per day (range 2,045-8,135) corresponding to a yearly 1.75 million steps. There was no significant correlation between clinical scores and step count measures. Even though this activity level was lower than for a group of healthy adults it was comparable to the activity level for other patients, for example, with hip arthroplasty as reported in the literature.