Sacroiliac pain after total hip arthroplasty: a combined analysis of clinical data and three-dimensional imaging in standing and sitting positions.

Purpose: Patients frequently complain of low back pain and sacroiliac joint pain (SIP) following total hip arthroplasty (THA). We hypothesized that patients with SIP would display different pelvic incidence (PI) values between standing and relaxed sitting positions, indicative of increased motion in the sacroiliac joints.

Methods: In this retrospective case-control study, 94 patients who underwent unilateral THA and experienced SIP were compared with 94 control patients without SIP.

Patient perception of leg length after total hip arthroplasty does not correlate with sagittal lumbar spine stiffness, history of spinal pathology or fusion.

Purpose: Although spinal pathology or fusion can change patients' posture and pelvic orientation, their correlation with perception of limb length discrepancy (LLD) after total hip arthroplasty (THA) is not well understood. We hypothesised that LLD perception after THA would not correlate with a history of spinal pathology, fusion or sagittal lumbar spine stiffness among patients who underwent THA.

Methods: Four hundred consecutive patients who underwent THA and had a complete set of anteroposterior and lateral EOS® imaging in standing and sitting positions were included in this retrospective case-control study.

Small Random Angular Variations in Pelvic Tilt and Lower Extremity Can Cause Error in Static Image-based Preoperative Hip Arthroplasty Planning: A Computer Modeling Study.

Background: Many THA simulation models rely on a limited set of preoperative static radiographs to replicate sagittal pelvic tilt during functional positions and to recommend an implant orientation that minimizes the risk of prosthetic impingement. However, possible random changes in pelvic or lower extremity angular motions and the effect of coronal and axial pelvic tilt are not included in these preoperative models.

Questions/purposes: (1) Can prosthetic impingement occur if the pelvic tilt or lower extremity alignment randomly varies up to ± 5° from what is measured on a single preoperative static radiographic image? (2) Do changes in coronal and axial pelvic tilt or lower extremity alignment angles have a similar effect on the risk of prosthetic impingement?

Methods: A de-identified pelvis and lower-body CT image of a male patient without previous THA or lower extremity surgery was used to import the pelvis, femur, and tibia into a verified MATLAB computer model.

Femoral stem neck geometry determines hip range of motion shape : a computer simulation study.

Aims: In computer simulations, the shape of the range of motion (ROM) of a stem with a cylindrical neck design will be a perfect cone. However, many modern stems have rectangular/oval-shaped necks. We hypothesized that the rectangular/oval stem neck will affect the shape of the ROM and the prosthetic impingement.

How much change in pelvic sagittal tilt can result in hip dislocation due to prosthetic impingement? A computer simulation study.

Developing spinal pathologies and spinal fusion after total hip arthroplasty (THA) can result in increased pelvic retroversion (e.g., flat back deformity) or increased anterior pelvic tilt (caused by spinal stenosis, spinal fusion or other pathologies) while bending forward.

Is Combined Anteversion Equally Affected by Acetabular Cup and Femoral Stem Anteversion?

Background: To create a safe zone, an understanding of the combined femoral and acetabular mating during hip motion is required. We investigated the position of the femoral head inside the acetabular liner during simulated hip motion. We hypothesized that cup and stem anteversions do not equally affect hip motion and combined hip anteversion.

Lumbar and cervical viscoelastic disc replacement: Concepts and current experience.

The ideal lumbar and cervical discs should provide six degrees of freedom and tri-planar (three-dimensional) motion. Although all artificial discs are intended to achieve the same goals, there is considerable heterogeneity in the design of lumbar and cervical implants. The "second generation total disc replacements" are non-articulating viscoelastic implants aiming at the reconstruction of physiologic levels of shock absorption and flexural stiffness.

Sagittal Spinopelvic Translation Is Combined With Pelvic Tilt During the Standing to Sitting Position: Pelvic Incidence Is a Key Factor in Patients Who Underwent THA.

Background: Sagittal spinopelvic translation (SSPT) is the horizontal distance from the hip center to the C7 plumb line (C7PL). SSPT is an important variable showing the overall patient balance in different functional positions which could affect the rate of hip instability. This study investigates the SSPT modification in patients who underwent total hip arthroplasty (THA).

Low pelvic incidence is a risk factor for intraoperative complications in minimally invasive anterolateral approach for total hip arthroplasty.

Background: Minimally invasive anterolateral approach (ALA) has gained popularity in recent years as better postoperative functional recovery and lower risk of postoperative dislocation are claimed. However, difficulties for femur exposure and intraoperative complications during femoral canal preparation and component placement have been reported. This study analyses the effect of anatomical factors on difficulties for femoral access and intraoperative complications with a modified minimally invasive ALA.

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.

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

Background: 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 biplanar x-rays.

Does Patients' Perception of Leg Length After Total Hip Arthroplasty Correlate With Anatomical Leg Length?

Background: This study assessed the correlation among the patients' perception of the leg length discrepancy (LLD) after total hip arthroplasty (THA) and the anatomical and functional leg length, pelvic and knee alignments, and foot height.

Methods: Patients without significant spinal pathology or previous spine or lower extremity surgery who underwent primary THA (101 patients) were evaluated using EOS images obtained in standing position. All 3-dimensional measures were evaluated and compared for the repeatability and reproducibility and correlation with patients' perception of leg length.

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.

Acetabular and Femoral Anteversions in Standing Position are Outside the Proposed Safe Zone After Total Hip Arthroplasty.

Background: Although most hip dislocations occur in either standing or sitting position, the safe zone for implant position is defined for the supine position. Our goal was to determine preoperative and postoperative pelvis and hip orientations and whether the safe zone defined in supine position can be used to assess standing radiographs.

Methods: Preoperative and postoperative three-dimensional EOS images were assessed in 66 total hip arthroplasty patients.

What is the Impact of a Spinal Fusion on Acetabular Implant Orientation in Functional Standing and Sitting Positions?

Background: This study used EOS imaging of primary total hip arthroplasty (THA) patients, with and without predating spinal fusion, to investigate (1) the impact of spinal fusion on acetabular implant anteversion and inclination, and (2) whether more extensive spinal fusion (fusion starting above the thoracolumbar junction or extension of fusion to the sacrum) affects acetabular implant orientation differently than lumbar only spinal fusion.

Methods: Ninety-three patients had spinal fusion (case group), and 150 patients were without spinal fusion (controls). None of the patients experienced dislocation.

Are advanced three-dimensional imaging studies always needed to measure the coronal knee alignment of the lower extremity?

Background: Coronal malalignment of the lower extremity is closely related to the onset and progression of osteoarthritis. Restoring satisfactory alignment after tibial osteotomy improves the long-term success of this conservative surgery. The purpose of our study was to determine (1) if there is a difference between two-dimensional (2D) and 3D measurements of the hip-knee-ankle (HKA) angle between the mechanical axes of the femur and the tibia, (2) which parameter most affects 2D-3D HKA measurement, and (3) the percentage of patients who are at risk of error in HKA measurement.

The global alignment in patients with lumbar spinal stenosis: our experience using the EOS full-body images.

Lumbar stenosis is frequently observed and treated by spine surgeons. The extent of neurological decompression and the potential spinal fixation are the basic concerns when surgery is planned. But this segmented approach to the problem is sometimes insufficient due to the complex functional situations induced by a sagittal imbalance of the patient and the combination of pathologies known as hip-spine or knee-spine syndromes.

Do Patients' Perceptions of Leg Length Correlate With Standing 2- and 3-Dimensional Radiographic Imaging?

Background: This study compared 2- and 3-dimensional (2D and 3D) radiographic measurements of anatomical and functional leg length and knee coronal and sagittal alignments and correlated these measurements with patients' leg-length perceptions.

Methods: Patients without symptomatic spinal pathology, previous surgery of the spine, and lower extremities (140 lower extremities) were evaluated on EOS images obtained in standing position. Numerous measurements of each limb were compared to the contralateral limb.

Offset and anteversion reconstruction after cemented and uncemented total hip arthroplasty: an evaluation with the low-dose EOS system comparing two- and three-dimensional imaging.

Purpose: Accurate evaluation of femoral offset is difficult with conventional anteroposterior (AP) X-rays. The EOS imaging system is a system that makes the acquisition of simultaneous and orthogonal AP and lateral images of the patient in the standing position possible. These two-dimensional (2D) images are equivalent to standard plane X-rays.

Preoperative evaluation of the cervical spondylotic myelopathy with flexion-extension magnetic resonance imaging: about a prospective study of fifty patients.

Study Design: The authors evaluated preoperative modifications of the cervical spinal canal in flexion and extension in 50 patients with cervical spondylotic myelopathy (CSM) and looked for impingement of the spinal cord not diagnosed in the neutral position.

Objective: To evaluate the usefulness of preoperative flexion-extension magnetic resonance imaging (MRI) for patients with CSM.

Summary Of Background Data: Dynamic factors contribute to CSM.

Modification of pelvic orientation after total hip replacement in primary osteoarthritis.

The acetabular anteversion angle varies according to the position of the pelvis. The objective goal of our study was to investigate changes in pelvic orientation after total hip replacement for primary osteoarthritis. We studied 89 patients who underwent total hip replacement for primary unilateral osteoarthritis.

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.

Optimization of total hip arthroplasty implantation: is the anterior pelvic plane concept valid?

The anterior pelvic plane (APP) is currently used as superficial anatomical landmark for three-dimensional orientation during total hip arthroplasty (THA), specifically when using computer aided surgery. However, the actual parameter for characterizing the pelvic orientation is the sacral slope, which correlates with other functional spinal parameters. The goal of the paper was to investigate relationships between APP and sacral slope.

Evaluation of the 96/4 PLDLLA polymer resorbable lumbar interbody cage in a long term animal model.

Arthrodesis using interbody cages has demonstrated high fusion rates. However, permanent cages are exposed to stress-shielding, corrosion, and may require explanation when necessary. Polylactic acid (PLA) bioresorbable cages are developed for avoiding these problems, but significant tissue reaction has been reported with 70/30 PLDLLA in some preclinical animal studies.