Pre-contoured Rods in Deformity Surgery: Is the Juice Worth the Squeeze?

Introduction: Achieving optimal alignment targets in deformity surgery requires thorough preoperative planning. Patient specific instrumentation has evolved in the recent years. Careful planning software can assist the surgeon in obtaining the ideal alignment parameters for successful outcome. This can then be translated into surgeon specific pre-contoured rods which could offer some benefits in the operative setting.

Methods: A retrospective review of patients who were treated with UNiD rods were identified from a single surgeon. A 1:1 match was performed using an existing deformity database in patients who underwent intraoperative bending. All patients had either a 3 or 6 month postoperative radiograph. Pelvic parameters were captured from the preoperative, alignment planning, and postoperative radiographs. The rods were prefabricated based on the software assisted surgical plan.

Results: 43 patients who were treated with UNiD rods were identified. 23 patients met inclusion criteria, and 23 patients were matched by PI, age, and gender. Mean PI was 59 and 60 for the UNiD and pre bent groups, respectively. L1PA goal accuracy (within 5 degrees) was 87% in the pre-contoured and 74% in the intra-op bent rod group (p=0.46). There was a statistically significant difference in T4PA goal accuracy which was 74% and 43.5% in the pre-contoured and bent rod groups, respectively (p=.036).

Conclusion : While L1PA target attainment was similar between the two cohorts, patients treated with UNiD rods demonstrated significantly improved T4PA goal achievement. Pre-contoured rods may offer several benefits including decreased operative time, reduced surgeon mental and physical fatigue, and less notching/weakening of the rod. Future studies are needed to identify potential benefits including cost analysis of pre-contoured rods in deformity surgery