Influence of kinematics of the lumbopelvic complex in hip arthroplasty dislocation: from assessment to recommendations.

INTRODUCTION: In total hip arthroplasty (THA), misplacement of the implant can provide instability. Adequate orientation of the acetabular cup is a challenge due to variations in inter-individual anatomy and kinematics of the pelvis in everyday life. The aim of this study was to characterize the kinematic factors influencing the risk of dislocation in order to give recommendations for optimal placement of the cup. We hypothesized that the lack of pelvic adaptation would influence the risk of prosthetic instability and motivate adapted. MATERIALS AND METHODS: Eighty patients with primary unilateral THA were included in a matched case-control study. Seventy-four patients were divided into two groups: group 1 (G1) consisting of patients with postoperative THA dislocation (37 patients) and group 2 (G2), without episodes of dislocation within two years postoperatively (37 patients). In both groups, spino-pelvic parameters and cup orientation were measured in standing and sitting positions with EOS® X-ray imaging and compared to each other between 12 and 24 months post-operatively. RESULTS: No significant difference between the two groups was found for static parameters. In a sitting position, a lack of pelvic retroversion with a significant lower variation in sacral slope was observed in group 1 (8.0° ± 9.3 for G1 versus 14.7° ± 6.2 for G2, p < 0.01). Twenty-two (59%) patients with THA instability had sacral slope variations of less than 10° versus eight (21% of patients) with stable THA (p < 0.01). Cup orientation in the Lewinnek safe zone was not significantly different (59% vs 67%, p = 0.62), and the spino-pelvic parameters and cup orientation measured did not change between the standing and sitting positions. However, only 14 (37%) cups in G1 were in the functional safe zone versus 24 (67%) in G2 (p = 0.03). CONCLUSION: Static parameters of the sagittal spinopelvic balance have a low predictive value for prosthetic instability. Dynamic analysis is essential. Kinematic parameters must be taken into account in determining the ideal position of the cup or stem. Stiffness with locked standing or sitting pelvis must be integrated in order to determine a personalized safe zone. LEVEL OF EVIDENCE: Level III (matched case-control study).

Esophageal perforation caused by a thoracic pedicle screw.

This grand round raises the risk of a rare complication that can be avoided with the knowledge of the particular anatomy of scoliosis vertebra. Transpedicular screws have been reported to enhance the operative correction in scoliosis surgery. The narrow and inconsistent shape of the thoracic pedicles makes the placement of pedicle screws technically challenging. Furthermore, in thoracic curves, the close proximity of the spinal cord and major soft tissue structures also adds a greater risk to the procedure. The esophagus lies close to the upper thoracic vertebras and, an anterior cortical perforation can cause esophageal injury. We report a case of anterior cortical perforation by a T4 pedicle screw complicated by an esophageal perforation in a 15-year-old girl with convulsive encephalopathy. She was operated for a severe neurological scoliosis (Rett syndrome). Her neurological condition deteriorated 3 years after the posterior spinal surgery, requiring a percutaneous gastrostomy. An intra-esophageal screw was discovered incidentally during an endoscopy. We decided not to remove this screw, because the patient's health status presented a surgical contraindication. The patient showed no apparent discomfort at the 10-year follow-up examination after spinal arthrodesis. Esophageal perforation caused by a posterior pedicle screw is very rare. We highlight the risk of injury to esophagus from pedicle screws in upper thoracic vertebra. The systematic removal of a malpositioned screw must be discussed, on a case-to-case benefit-risk basis, especially if the patient has numerous comorbidities, given the long-term tolerance of a number of these improperly positioned implants.

Percutaneous arthroscopic calcaneal osteosynthesis for displaced intra-articular calcaneal fractures: Systematic review and surgical technique.

BACKGROUND: The aim of this study was to systematically evaluate the available literature on technique and outcomes of percutaneous arthroscopic calcaneal osteosynthesis for displaced intra-articular calcaneal fractures. METHODS: A systematic review of the literature available in MEDLINE, EMBASE, and the Cochrane Library database was performed, including studies from January 1985 to august 2018. The literature search, data extraction, and quality assessment were conducted by 2 independent reviewers. The surgical technique and perioperative management, clinical outcomes scores, radiographic outcomes and complication rate were evaluated. RESULTS: Of 66 reviewed articles, 8 studies met the inclusion criteria. The included studies reported on the results of 152 patients. At last follow up the mean American Orthopaedic Foot & Ankle Society ankle-hindfoot was ranging from 72.1 to 94.1. The complication rate was low, including only one superficial infection. CONCLUSIONS: The studies included were of too little level of evidence to allow for data pooling or meta-analysis. However, the percutaneous arthroscopic calcaneal osteosynthesis seems to be a good option for displaced intra-articular calcaneal fractures with a low complication rate. Appropriately powered randomized controlled trials with long-term follow up are needed to confirm the efficacy of this technique. LEVEL OF EVIDENCE: Level III, systematic review of Level III studies.

Prospective Evaluation of Spino-Pelvic Parameters with Clinical Correlation in Patients Operated with an Anterior Lumbar Interbody Fusion.

STUDY DESIGN: Prospective study. PURPOSE: The goal of this study was to evaluate the impact of anterior lumbar interbody fusion (ALIF) on L5-S1 level for restitution of distal segmental lordosis and to investigate its consequences on spino-pelvic parameters and the global sagittal balance. OVERVIEW OF LITERATURE: Lumbar surgery must be adapted to the spinal morphology in order to restore an adequate relation between pelvic and spinal parameters and especially to the pelvic incidence. METHODS: An observational, prospective study was conducted between January 2013 and May 2017. Eighty-six patients were treated by L5-S1 ALIF procedure regardless of disc replacement above L5-S1 level. Thirty-seven patients were included and subset analyses were performed on 25 patients operated on an isolated ALIF L5-S1 (group 1), and 12 patients with hybrid surgery consisting of an L5- S1 ALIF procedure and a L4-L5 lumbar disc replacement (group 2). Clinical parameters were analyzed using Visual Analog Scale (VAS) and Oswestry Disability Index (ODI) at M0 (preoperative) and M12 (12 months). Lumbo-pelvic parameters were assessed on a standing full-spine X-ray, preoperatively and at M12 after surgery. RESULTS: We observed a significant evolution of L1-S1 lumbar lordosis (p <0.001) with a significant increase of the distal arch L4-S1 lordosis (p <0.001) and decrease of the proximal arch lordosis (p =0.03). Preoperatively, 27% of the patients were unbalanced. Significant variation in sagittal balance parameters was observed, with a decrease of the sagittal vertebral axis (p <0.001). VAS and ODI improved significantly but no correlation was found. An evolution in the same direction was found in the two subgroup analyses. CONCLUSIONS: ALIF procedure on L5-S1 level allowed a reconstruction of lumbosacral segmental lordosis, modification of global lordosis, without variation of spino-pelvic parameters except an improvement in sagittal balance.

Dual mobility device reduces the risk of prosthetic hip instability for patients with degenerated spine: A case-control study.

INTRODUCTION: The pelvic incidence is an anatomical and biomechanical pelvic parameter determining spine sagittal morphology and kinematics. Stiffening of the lumbo-pelvic complex, a result of degeneration, affects the functional cup positioning, putting prosthetic hip patients at risk of instability. The anti-dislocation dual mobility (DM) device may be clinically advantageous by reducing the risk of prosthetic instability for older patients with spine ageing. Our study aims to answer the following questions: (1) is there a relationship between prosthetic hip instability and the standing cup position, (2) is there a relationships between prosthetic hip instability and the pelvic incidence, (3) is there a relationships between prosthetic hip instability and the severity of the spine degeneration?, (4) is the DM cup device an effective option for reducing the risk of prosthetic instability related to spine degeneration? HYPOTHESIS: There is a relationship between prosthetic hip instability and the standing cup position and pelvic parameters. METHODS: Case-control study on prospectively collected data since 2009. From 1672 conventional total hip replacements (THR-5.4% dislocation rate) and 1056 DM-THRs (1.1% dislocation rate) performed at our institute since 2009, we created three groups: 33 patients with unstable THR (group 1-case), 41 patients with stable THR (group 2-control), and 42 patients with stable DM-THR (group 3-control). The cup orientation was measured on standing pelvic radiographs and the spino-pelvic parameters were measured on standing EOS™ biplanar images or lateral full spine radiographs. RESULTS: By comparing patients from group 1 with those of group 2 we found they had similar cup position (57% versus 51% fitting the safe zone, p=0.58), higher pelvic incidence (58° versus 51°, p=0.01), and more severe spine degeneration (smaller anterior pelvic plane Tilt (2° versus 7° [p=0.002]), a larger pelvic incidence-lumbar lordosis mismatch (17° versus 8° [p=0.005]), and a higher proportion of spino-sacral angle<127° (70% versus 43%, (p=0.02)). Patients from group 3 had similar cup position, pelvic incidence, and spine degeneration compared to patients from group 1. DISCUSSION/CONCLUSION: Patients with spine-hip relation type 2C/D (high pelvic incidence and severe spine degeneration) have an increased risk of instability that is partly compensated for by the use of a DM device. Preoperative screening of patients with abnormal spine-hip relation would improve THR planning and reduce the risk of prosthetic hip instability. The use of a DM device on spine-degenerated elderly patients is probably sound. LEVEL OF EVIDENCE: III, case-control study.