Clinical StudyValidation of a new computer-assisted tool to measure spino-pelvic parameters
Introduction
The importance of sagittal alignment analysis in adult spinal deformity (ASD) has long been emphasized [1], and numerous studies have reported the deleterious impact of spino-pelvic malalignment on patient-reported outcomes [2], [3]. Accurate sagittal alignment analysis has become an essential tool in treatment planning for ASD and can be used to calculate the correction needed [4], [5], [6]; inadequate treatment can result in poor postoperative alignment and patient-reported outcomes [7], [8].
Despite its importance, analysis of the sagittal plane and individualized surgical planning can be an arduous practice. In response, dedicated software has emerged to simplify sagittal plane assessment. Multiple forms of digital measurement software have been shown to be faster, more accurate, more precise, and less variable than manual techniques [9], [10]. These computer-based measurements provide a step forward in sagittal spino-pelvic evaluation, but their application remains largely limited to research: although nearly 90% of spine surgeons recognize the importance of such software, less than half regularly use software to analyze and plan sagittal realignment procedures [11].
Even with computerized software, the process of spino-pelvic analysis on radiographs has until recently involved several complex steps, and many current software applications are considered time-consuming, technically demanding, and unpractical. Most existing dedicated spine software programs require extensive measurements to generate spino-pelvic parameter values [12], [13]. In one such case, the user must identify the femoral heads and the superior and inferior end plates of every single vertebra in the spine to generate measurements; in addition, such programs have complicated interfaces and are often limited to the computers in which they are installed. As a result, these programs are used primarily in the research realm, but are difficult to implement for routine clinical use.
Surgimap (Nemaris Inc, New York, NY, USA) is a dedicated spine measurement and surgical planning software that was developed to be applicable in both the research and the clinical realms [14]. Within one application, users can upload images and use a variety of tools for measuring coronal and sagittal radiographs. By identifying key parameters on the radiograph with 11 cursor clicks, an entire collection of spino-pelvic parameters can be automatically and instantaneously generated. Parameters can be modified, shown to patients, and saved by the clinician for future analysis. Finally, Surgimap can be run from either a desktop or a portable storage device (such as a universal serial bus [USB]), allowing the entire database of images and measurements to be carried by the physician to the office, the operating room, or any other location, without the need for additional software or specific operating systems. Authors have advocated the use of this platform based on its effective and clinically useful osteotomy simulations and surgical planning [14]. The reliability of this software has been established in a recent study [15], but since that publication, a more sophisticated, yet user-friendly sagittal alignment tool has been incorporated into the software.
The current study validates the accuracy and reliability of this specialized sagittal alignment tool. By simplifying the sagittal plane analysis, the software can provide a more efficacious and applicable method to routine clinical evaluation of important spino-pelvic parameters.
Section snippets
Patient population
For this single-center study, subjects were selected from a database of ASD patients. Institutional review board approval was obtained before study initiation. Subjects were enrolled if they were older than 18 years and met radiographic criteria for ASD: coronal Cobb angle >20°, sagittal vertical axis (SVA) >5 cm, pelvic tilt (PT) >25°, or thoracic kyphosis (TK) >60°. Patients were excluded if their deformity was caused by malignant, neuromuscular, infectious, or traumatic etiology. Both
Part 1: accuracy
Mean values of key parameters as measured by SpineView were as follows: PT: 26.5°±14.3, PI: 62.2°±12.3, PI–LL: 10.4°±28.0, and SVA: 39.8 mm±70. Mean values for the same parameters as measured by Surgimap were PT: 26.5°±14.3; PI: 62.0°±112.3; PI-LL: 10.4°±27.9; SVA: 38.4 mm±69. Mean absolute differences and SDs are shown in Table 1. The minimum differences for all angular parameters was less than or equal to 0.01°. The pelvic parameters (PI, SS, and PT), which were directly measured by anatomic
Discussion
Sagittal plane analysis is critical in the evaluation and treatment of spinal pathology, as well as the assessment of postoperative alignment success. Radiographic evaluation is crucial, as radiographic measurements usually correlate well with patient-reported outcomes [24]. Although most providers appreciate the importance of radiographic evaluation, there is still a gap between the awareness of its utility and its use in daily practice. One of the main limitations of spine measurement
Conclusions
Findings from this study demonstrate the accuracy, intra- and inter-observer reliability, and efficacy of a spine measurement software tool. Although measurements based on points were more reliable than end plate angle parameters, all parameters showed good to excellent validity and reliability. The software allows for measurement of radiographs with ease and speed, providing a vast array of opportunities for assessment of spinal pathology for physicians and researchers alike. Thus, the current
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FDA device/drug status: Approved (Surgimap 2.0).
Author disclosures: RL: Nothing to disclose. EF: Nothing to disclose. JKH: Nothing to disclose. VC: Fellowship Support: SOFCOT (C, Paid directly to institution/employer). BD: Nothing to disclose. BL: Nothing to disclose. VL: Stock Ownership: Nemaris Inc (20% Ownership, Paid to author); Speaking and/or Teaching Arrangements: Medicrea (D, Paid to author), DePuy (C, Paid to author), Nemaris Inc (20% Ownership, Paid to author), MSD (B, Paid to author); Board of Directors: Nemaris Inc (amount unknown, Stock ownership); Grants: DePuy (D, Paid directly to institution/employer), SRS (D, Paid directly to institution/employer), NIH (D, Paid directly to institution/employer). FS: Royalties: MSD (B, Paid to author), K2M (B, Paid to author); Stock Ownership: Nemaris Inc (30% Ownership, Paid to author); Consulting: K2M (D, Paid to author), Medicrea (E, Paid to author), MSD (B, Paid to author); Speaking and/or Teaching Arrangements: MSD (B, Paid to author), Medicrea (C, Paid to author), K2M (B, Paid to author), Biomet (B, Paid to author), NuVasive (B, Paid to author); Board of Directors: Nemaris Inc (amount unknown, 20% Ownership, Paid to the author); Grants: DePuy (E, Paid directly to institution/employer), MSD (E, Paid directly to institution/employer), AO (D, Paid directly to institution/employer).
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