Comments to "Utility of Patient-Specific Rod Instrumentation in Deformity Correction: Single Institution Experience" By Sadrameli et al.

Dear Editor:

We completely agree with Sadrameli et al.[1]) regarding the utility of patient-specific rods (PSR) in surgery for spinal deformities[2-5]). We find it useful to share the results of this innovative procedure during early follow-up that can contribute to the advancement in this field of spine surgery[2],[5]).

To our knowledge, in addition to the literature cited, two other studies on PSR in adults have been published in indexed journals by two French teams with radiologic results at 1 year of follow-up: one about 60 patients who underwent spinopelvic fusion for various conditions[5]), and the second, which involved 86 adults with spinal deformity[6]).

We commend Sadrameli et al, who compared their PSR patients with a matched series of patients, who underwent spine fusion with conventional rods, whereas the other studies report a series of PSR without comparison. We also believe it is worthy and honest to release nonsignificant comparison. The authors suggest the small number of subjects can partially explain this. A post-hoc power analysis should be performed to better appreciate the significance of these results and to lay the foundations of a prospective comparative study with a calculated number of subjects.

Radiological results of this paper are difficult to compare with previous literature, as both the baseline parameters and the criteria for good results were different. However, consistent with previous series, sagittal results were generally good or excellent[5],[6]). All spinopelvic parameters significantly improved from preoperative radiography to postoperative radiography, and were similar between the surgical plan and actual performed alignment. Interestingly, pelvic slope and C7 Sagittal Vertical Axis were better corrected than in previous studies[5],[6]). A potential explanation is that preoperative imbalance was less important than in previous reports.

Other publications from the same teams are expected, whose practices already take account of the lessons learned from preliminary experience. Wouldn't we perform a multicenter study?

Conflicts of Interest:

FS received funding for congresses from SpineEst, Medicrea Int. and Euros

VF is a paid consultants for Medicrea Int. and Clariance and receives royalties from Medicrea Int. and Clariance

VR has no conflicts to declare

CYB received funding for congresses from Medtronic, Medicrea Int., Implanet, Ethicon and Noraker.

Sources of Funding: no specific funding