Cervical spine surgery in ankylosing spondylitis : review and current concept

Ankylosing spondylitis of the cervical spine is associated with stiff kyphosis and increased risk of transversal unstable fracture. A spine surgeon may be involved mainly in the management of trauma cases, but in some situations, corrective surgery of a kyphotic cervical deformity is needed. Both types of cases carry specific aspects and rely on principles that differ from those associated with more common cervical surgery. This paper is a review of the literature regarding cervical surgery in cases of ankylosing spondylitis. It addresses practical technical questions

Total Hip Arthroplasty in Patients With Parkinson Disease: Improved Outcomes With Dual Mobility Implants and Cementless Fixation

Background: Parkinson disease (PD) results in severe limitation in ambulation caused by abnormality of gait and posture. The rate of complications, including fractures and dislocation after total hip arthroplasty (THA), can be higher among these patients. The goal of this study was to investigate the long-term outcomes of primary and revision THAs with cementless dual mobility implants. Methods: This retrospective study examines 59 PD patients who had surgery between 2002 and 2012. All the primary cases were performed for osteoarthritis and all patients received cementless acetabular implants with dual mobility bearing surface. The femoral stem was cemented in 4 patients who underwent revision surgery. The mean follow-up time was 8.3 years (4-14 years). Results: Good to excellent pain relief was achieved in 53 of 57 patients at the 2-year follow-up and in 40 of 47 patients at their latest follow-up. The most common medical complication was cognitive impairment (12 of 57 patients). One patient sustained an intraprosthetic hip dislocation 9 years after surgery, which required revision. Four patients sustained periprosthetic femoral fractures with well-fixed stem, requiring open reduction and internal fixation. The disability had increased in 68% of the patients in the latest follow-up visit. Discussion: Our study shows that elective primary or revision THA using cementless implants with dual mobility bearing surface in patients with PD provides satisfactory long-term outcomes, although many of these patients may see a general worsening of their activities over time due to PD

How do global sagittal alignment and posture change after total hip arthroplasty?

Background: Postural change after total hip arthroplasty (THA) is still a matter of discussion. Previous studies have mainly concentrated on the pelvic motions. We report the post-operative changes of the global sagittal posture using pelvic, spinal, and lower extremities parameters. Methods: 139 patients (primary THA, without previous spinal or lower extremity surgery) were included. We measured pelvic parameters [SS, sacral slope; PI, pelvic incidence; PT, pelvic tilt; APP angle, anterior pelvic plane angle] and the global posture parameters (SVA, sagittal vertical angle; GSA, global sagittal angle; TPA, T1 pelvic angle). Patients were categorized into low PI group  65°. Results: Mean GSA and SVA decreased post-operatively (p = 0.005 and p = 0.004 respectively). The TPA change was not significant (p = 0.078). In the low PI group, GSA (5.4 ± 5.0 to 4.3 ± 4.0, p = 0.005) and SVA (5.4 ± 4.9 to 4.2 ± 4.1, p = 0.038) decreased with more posterior pelvic tilt. Post-operative TPA was significantly higher (8.4 ± 10.6 to 9.8 ± 10.7; p = 0.048). In the medium PI group, SVA decreased (4.2 ± 4.6 to 3.6 ± 4.5, p = 0.020) with more posterior pelvic tilt. In the high PI group, pelvic and global posture parameters did not evolve significantly. Conclusion: PI is the key determining factor in pelvic tilt modification after THA. Patients with low PI demonstrate significant modification in spine, pelvic, and lower extremities. Pelvic tilt is the main adaptation mechanism for medium incidence patients whereas pelvic tilt does not change in high PI patients after surgery

Stand-to-Sit Kinematics of the Pelvis Is Not Always as Expected: Hip and Spine Pathologies Can Have an Impact

Introduction; Stand to sit pelvis kinematics is commonly considered as a rotation around the bicoxofemoral axis. However, abnormal kinematics could occur for patients with musculoskeletal disorders affecting the hip-spine complex. The aim of this study is to perform a quantitative analysis of the stand to sit pelvis kinematics using 3D reconstruction from bi-planar x-rays. Material & Methods; Thirty volunteers as a control group (C), 30 patients with hip pathology (Hip) and 30 patients with spine pathology (Spine) were evaluated. All subjects underwent standing and sitting full-body bi-planar x-rays. 3D reconstruction was performed in each configuration and then translated such as the middle of the line joining the center of each acetabulum corresponds to the origin. Rigid registration quantified the finite helical axis (FHA) describing the transition between standing and sitting with two specific parameters. The orientation angle (OA) is the signed 3D angle between FHA and bicoxofemoral axis and the rotation angle (RA) represents the signed angle around FHA. Results; Mean OA was -1.8° for C group, 0.3° for Hip group and -2.4° for Spine group. There was no significant difference in mean OA between groups. However, variability was higher for Spine group with a standard deviation of 16.4° compared to 10.8° in C group and 12.3° in Hip group. Mean RA in C group was 18.1° (SD 9.1°). There was significant difference in RA between Hip and Spine groups (21.1° SD 8.0°) and 16.4° (SD 10.8°), respectively) (p=0.04). Conclusion; Hip and spine pathologies affect stand to sit pelvic kinematics

Mathematical evaluation of jumping distance in total hip arthroplasty: Influence of abduction angle, femoral head offset, and head diameter

Background and purpose The jumping distance (JD) is the degree of lateral translation of the femoral head center required before dislocation occurs. The smaller the distance, the higher the theoretical risk of dislocation. The aim of our study was to evaluate this jumping distance and its variation according to the characteristics of the implant, and also the theoretical gain in using large head diameters of above 38 mm

Total Hip Prostheses in Standing, Sitting and Squatting Positions: An Overview of Our 8 Years Practice Using the EOS Imaging Technology

This is an open access article licensed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted, non-commercial use, distribution and reproduction in any medium, provided the work is properly cited.More total hip arthroplasty (THA) is performed worldwide and especially in younger and more active patients compared to earlier decades. One of the focuses of THA research in the future will be on optimizing the radiological follow-up of these patients using 2D and 3D measurements of implants position while reducing the radiation dose delivered. Low-dose EOS(®) imaging is an innovative slot-scanning radiograph system providing valuable information in patient functional positions (standing, sitting and even squatting positions). EOS has been proven accurate and reliable without significant inconvenience caused by the metallic artifacts of implants. The ability to obtain precise data on implant orientation according to the patient posture opens new perspectives for a comprehensive analysis of the pelvic frontal and sagittal balance and its potential impact on implants function and failures. We report our 8 years experience on our first 300 THA patients using this technology routinely for pre and post op evaluation. Our results will be compared and confronted with the actual literature about this innovative technology. We shall especially emphasize our experience about patients with abnormal posture and the evolution of the subject over time, because the phenomenon of an aging spine is frequently associated with the process of aging hips