Multiple-rod constructs in thoracolumbar reconstructive spine surgery: Building a novel classification of heterogeneous rods for multiple etiologies (CHRoME) scoring system

Surgical management of complex spine disorders with instrumentation continues to expand. This present study investigates the possible therapeutic uses of a categorization nomenclature system that is widely recognized for multiple-rod constructs in spine reconstruction surgery utilizing a modified Delphi technique. An extensive literature review identified articles on multiple-rod constructs where definitions and names of multiple-rod constructs were categorized according to inclusion criteria. An expert panel of spine surgeons using a modified Delphi process established the framework of terms for the multiple-rod scheme for the classification of heterogeneous rods for multiple etiologies (CHRoME). Four key questions based on a review of spinal x-ray films and relevant clinical indications were used to create CHRoME: number of rods present, extension of the rostral construct, purpose of the working rod, and number of screws for pelvic fixation. Next the CHRoME score was used by a panel of spine surgeons to evaluate images from a sample of 10 case scenarios. Our expert panel were able to classify images with very good agreement and high rates of inter-rater reliability (kappa coefficient 0.83; 95 % CI: 0.69–0.96). With a kappa coefficient of 0.94 (95 percent CI, 0.90 to 0.99), the intra-rater reliability was almost flawless. The novel classification of heterogeneous rods for multiple etiologies (CHRoME) score, based on 4 essential questions, is used to define multiple-rod constructs and gives a consistent description of the numerous ways that instrumentation is used in spine surgery.