The Institute of Health Metrics and Evaluation (IHME) at the University of Washington measured spending in the USA according to condition. They found that $88 million per year was billed for Back Pain.

https://www.theguardian.com/society/2017/feb/10/epidemic-of-untreatable-back-and-neck-pain-costs-billions-study-finds?CMP=oth_b-aplnews_d-2