Prolotherapy?

[unixronin]

From the Mayo Clinic:

Prolotherapy involves injecting painful ligaments and tendons with sugar solutions that are intended to stimulate production of connective tissue.  A typical course of treatment is six to 10 sessions, sometimes with multiple injections at each session.

[...]

A 2007 review of five well-designed studies involving 366 participants concluded that prolotherapy alone was ineffective in treating chronic low back pain.  However, when combined with other treatments — such as spinal manipulation and exercise — prolotherapy may improve chronic low back pain.

The question I have to ask here is, if prolotherapy "may improve chronic low back pain", but only when combined with "other treatments such as spinal manipulation and exercise" which are known to improve lower back pain, does prolotherapy actually yield any improvement not attributable to the other, known effective, therapies it's being combined with?  In the absence of any stated finding of synergism, this seems a bit like saying "Painting one's toenails blue may be effective against bronchitis, when combined with antibiotics."  The article appears to damn prolotherapy with faint praise.