Pedicle screw placement safety with the aid of patient-specific guides in a case series of patients with thoracic scoliosis.

PURPOSE: Pedicle screw (PS) placement in thoracic scoliotic deformities can be challenging due to altered vertebral anatomy; malposition can result in severe functional disability or inferior construct stability. Three-dimensional (3D) printed patient-specific guides (PSGs) have been recently used to supplement other PS placement techniques. We conducted a single-center, retrospective observational study to assess the accuracy of PS placement using PSGs in a consecutive case series of pediatric and adult patients with thoracic scoliosis. METHODS: We analyzed the data of patients with thoracic scoliosis who underwent PS placement using 3D-printed PSG as a vertebral cannulation aid between June 2013 and July 2018. PS positions were determined via Gertzbein-Robbins (GR) and Heary classifications on computed tomography images. We determined the concordance of actual and preoperatively planned PS positions and defined the technique learning curve using a receiver-operating characteristic (ROC) curve. RESULTS: We performed 362 thoracic PS placement procedures in 39 consecutive patients. We classified 352 (97.2%), 2 (0.6%), and 8 (2.2%) screws as GR grades 0 (optimal placement), I, and II, respectively. The average instrumented PS entry point offsets on the X- and Y-axes were both 0.8 mm, and the average differences in trajectory between the planned and the actual screw placements on the oblique sagittal and oblique transverse planes were 2.0° and 2.4°, respectively. The learning process was ongoing until the first 12 PSs were placed. CONCLUSIONS: The accuracy of PS placement using patient-specific 3D templates in our case series exceeds the accuracies of established thoracic PS placement techniques.

Survival rate of total hip replacements with matched and with mixed components with 10.7 years mean follow-up.

BACKGROUND: Mixing and matching components from different manufacturers in total hip arthroplasty is a frequently used off-label praxis. The clinical consequences of this procedure have not been studied in detail. METHODS: 860 patients with matched and 1067 patients with mixed primary total hip replacement (THR) components carried out between 1 January 2002 and 31 December 2004, were selected from our Institution registry. The analysis endpoint was set at 1 January 2016. THRs with poorly performing components were excluded from study groups. Kaplan-Meier survival curves for both groups were calculated and compared using the Log-Rank test and the demographic data using the chi-square test. Correlations between demographic data and revisions were calculated using bivariate correlation. RESULTS: 28 revisions were carried out in the matched group and 67 in the mixed group. The 14-year overall survival probability was significantly better in the former (96.0%) than in the mixed group (92.7%) (p = 0.002). Survival, free of aseptic and septic failures, was statistically, significantly higher in the matched group (p = 0.026 and p = 0.007, respectively).The survival of the mixed subgroup with heads and stems from the same manufacturer did not differ statistically from that of the matched group (p = 0.079). CONCLUSIONS: In contrast to the results listed in the National Joint Registry and the New Zealand Joint Registry, the survival probability in our study was, statistically, significantly higher in total hip replacements using components of the same manufacturer. Importantly, mixing and matching the components of different manufacturers led to similar survival providing the head and the stem were from the same manufacturer.

Malpositioned pedicle screw in spine deformity surgery endangering the aorta: report of two cases, review of literature, and proposed management algorithm.

STUDY DESIGN: Case reports and review of the literature with a proposed management algorithm. OBJECTIVES: To report two cases of a potential vascular complication due to an incorrectly placed pedicle screw (PS) during spine deformity surgery. Relevant literature regarding the management of vascular complications is reviewed, and an evidence-based management algorithm is proposed. Aortic lesions represent a rare but potentially life-threatening complications with spine deformity and revision surgery, significantly increasing the risk. A management algorithm for an aortic lesion in the case of a malpositioned PS has not yet been published. METHODS: Case 1: An 18-year-old female with proximal thoracic spinal non-instrumented fusion underwent a revision corrective procedure due to a progressive right-sided thoracolumbar compensatory curve. However, postoperative computed tomography (CT) performed to evaluate the position of the PS revealed malposition of the left T9 PS, which was abutting the descending aorta with CT angiography excluding the perforation of the aorta. Case 2: A 17-year-old male was scheduled for correction of Lenke 3-C-N adolescent idiopathic scoliosis. Postoperative routine evaluation with low-dose CT revealed a left T9 PS paravertebral malposition, and subsequent CTA demonstrated that the thread of the PS was in contact with the descending thoracic aorta and an unlikely hemodynamically significant vessel injury. RESULTS: Successful removal of both malpositioned PS was performed. In the first case, a cardiovascular surgeon attended the operation if an urgent thoracotomy was needed, and in the second case, additional video-assisted thoracoscopic control of the aorta was performed during PS removal. CONCLUSIONS: Preoperative imaging in spinal surgery is essential to avoid major vascular and other complications when placing PS, especially in thoracic deformities. When a potential major vessel complication emerges, an interdisciplinary approach and an appropriate management algorithm are mandatory to make the best clinical decisions. LEVEL OF EVIDENCE: 4.