Table 1.

Mean pre-injection and post-injection NRS (back) and ODI for lumbar multifidus muscle PLRP injection through the follow-up period.

Outcome	Pre-inj. scores	Day 1	6 months	12 months	18 months	24 months	Difference in group means (95% CI)
NRS-back pain	8.8 ± (0.86)	7.2 ± (1.1)	4.57 ± (2.48)	3.45 ± (2.94)[1]	3.48 ± (2.93)[2]	3.5 ± (2.92)	5.31 ± (2.90)
ODI	73.48% (3.95)	63.1% (4.5)	29.44% (12.8)[3]	29.28% (12.8)[4]	29.26% (12.8)[5]	29.3% (12.8)	44.18% (12.7)

Values are mean standard deviation (SD), NRS = Numerical Rating Scale (0–10), ODI = Oswestry Disability Index, CI = Confidence Interval, the mean ODI score is multiplied by two to give the mean disability score which is expressed in the table. Difference in group means is expressed as the difference between pre-injection and post-injection values at the end of follow-up period. The mean ODI and (NRS) back scores for lumbar multifidus PLRP injection showed significant improvement at the end of the 2-years follow-up period, the mean ODI and (NRS) back scores showed statistically insignificant changes and remained low without significant increase again after initial significant improvement that started at the day-1 follow-up that reached maximum improvement by 6–12 months follow-up period post-injection. P (paired t test) < 0.001 *[1] P = 0.181, [2] P = 0.32, [3] P = 0.083, [4] P = 0.741, [5] P = 0.32.