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BACKGROUND: The spine surgeon’s understanding of an individual patient’s burden of disease and functional disability in daily life is shaped by patient-reported outcome measures (PROMs). Although PROMs are useful in understanding the patient’s perception of their disease, the use of PROMs constitutes a “snapshot” approach of single timepoint data capture, omitting day-to-day fluctuations in functional status. We introduce the concept of kinetics when considering continuous and objective postoperative patient monitoring with wearable sensors. METHODS: A prospective single-centre series was performed using patients either undergoing lumbar decompression for lumbar spinal stenosis (LSS) (n=12), or posterior lumbar fusion for degenerative spondylolisthesis (n=12). The Oswestry Disability Index (PROM) was conducted preoperatively and 12-weeks postoperatively. During this timeframe, continuous measurements of step count and distance travelled were made using a wrist-based wearable accelerometer. RESULTS: Over the 12-week study period, mean daily step count for all participants improved from 4,700 to 7,700 steps per day (P=0.013), following an initial dip in total steps taken. The mean daily distance travelled improved from 3,300 to 5,300 meters per day (P=0.003). Decompression group recovered at a faster rate than the fusion group. CONCLUSIONS: Although overall improvement was similar between the decompression and fusion groups, the recovery kinetics varied. The recovery kinetics approach of continuous postoperative monitoring provides additional insight to postoperative patient progress.

We present the case of an 85-year-old woman who presented to our clinic with neurogenic claudication due to lumbar spinal stenosis (LSS) over a period of two years. During this time a series of walking metrics were monitored including daily step count, walking speed, and step length. All metrics showed a deterioration over time and objectively document the disease progression of LSS (initial: walking speed =1.03 m/s, step length =0.49 m, and daily step count =3,136; final: walking speed =0.49 m/s, step length =0.37 m, and daily step count =334). At this time, the patient had also begun experiencing bilateral lower limb weakness and paraesthesia upon exertion, preventing her from mobilizing for more than a few meters at a time. After a shared decision-making process with the patient and her family, surgical management was recommended. The deterioration of the patient’s walking metrics matched their increasing requirement for walking assistance, with no walking assistance being needed initially, compared to a four-wheel walker being required in the weeks prior to her surgery. Therefore, the extent of walking deterioration may be able to inform clinical decision-making regarding appropriate walking assistance. To our knowledge, this is the first report that objectively documents the deterioration of LSS using walking metrics for such a prolonged duration of time.

Additional file 1: Supplementary Table S1. PRISMA-P 2015 Checklist. Supplementary Table S2. Eligibility criteria framed using the PICOTS approach. Supplementary Table S3. Search strategies for electronic databases. Supplementary Table S4. PROBAST- Prediction model Risk Of Bias ASsessment Tool.