Error of intraoperative measurement of stem anteversion is decreased by measuring in neutral hip position during total hip arthroplasty.

Background: Intraoperative stem anteversion, which is the angle between the lower leg axis and the trial-stem axis with hip flexion and adduction, is generally evaluated by the surgeon's visual estimation during total hip arthroplasty (THA). However, the conventional approach can be influenced by knee osteoarthritis or uncertain surgeon's observation point. Therefore, we developed a new method for measuring the stem anteversion angle in the neutral hip position using an original rod attached to the trial-stem perpendicular to the long axis and parallel to the stem neck.

Computer simulation based on in vivo kinematics of a replaced hip during chair-rising for elucidating target cup and stem positioning with a safety range of hip rotation.

Background After total hip arthroplasty, dislocation can occur when a patient unexpectedly assumes internal/external limb positions, even during chair-rising, which is a frequently activity of daily life. Therefore, determining the target cup position to avoid impingement in unexpected limb positions using in vivo data of daily life activities is critical. Methods A computer simulation was performed on 21 total hip arthroplasty patients using patient-specific component placements and hip kinematics obtained during chair-rising analysis using image-matching techniques.

Total hip arthroplasty after periacetabular osteotomy versus primary total hip arthroplasty: a propensity-matched cohort study.

Background: Controversy still exist regarding the outcomes of total hip arthroplasty (THA) after periacetabular osteotomy (PAO). The purpose of this study was to compare the clinical and radiologic outcomes of THA after PAO with primary THA based on balanced baseline characteristics with propensity score matching.

Methods: Using propensity score matching, 1:2 matched cohort to facilitate comparison between patients who underwent primary cementless THA with or without previous PAO.

How does transtrochanteric anterior rotational osteotomy change the dynamic three-dimensional intact ratio in hips with osteonecrosis of the femoral head?

Background: The intact ratio (the ratio of the intact area of the femoral head) on a two-dimensional anteroposterior radiograph is associated with the prognosis of hips with osteonecrosis of the femoral head after transtrochanteric anterior rotational osteotomy. However, changes of the three-dimensional intact ratio during dynamic weight-bearing activity and correlation of the three-dimensional intact ratio with clinical scores are still unknown.

Methods: Kinematics of eight hips with osteonecrosis of the femoral head that underwent anterior rotational osteotomy were analyzed using image-matching techniques during chair-rising and squatting preoperatively and postoperatively.

In vivo kinematic analysis of replaced hip during stationary cycling and computer simulation of optimal cup positioning against prosthetic impingement.

Background: Dynamic hip kinematics during stationary cycling after total hip arthroplasty (THA) have been unclear. Furthermore, no computer simulation of optimal cup position based on in vivo kinematics has yet been assessed.

Methods: This study consisted of 7 patients who underwent unilateral primary THA for symptomatic osteoarthritis.

In vivo kinematics, component alignment and hardware variables influence on the liner-to-neck clearance during chair-rising after total hip arthroplasty.

Background: There is an interest in quantifying dynamic hip kinematics before and after total hip arthroplasty (THA) during chair-rising: one of daily life activities.

Methods: The study consisted of 21 patients who underwent unilateral total hip arthroplasty for symptomatic osteoarthritis. We obtained continuous radiographs using a flat-panel X-ray detector while the participants rose from chair.

Dynamic hip kinematics before and after periacetabular osteotomy in patients with dysplasia.

Background: We prospectively analyzed the hip kinematics in patients with developmental dysplasia of the hip (DDH) before and after periacetabular osteotomy (PAO) and in healthy subjects while squatting to determine the influence of coverage of the femoral head on hip kinematics.

Methods: 14 hips in 14 patients with DDH and 10 hips in 10 volunteers were included. Continuous radiographs while squatting and computed tomography images were obtained to assess the in vivo kinematics of the hip and the rim-neck distance using density-based 3D-to-2D model-to-image registration techniques.

Dynamic hip kinematics during recreational classical ballet and hula dance after total hip arthroplasty: two case reports.

Background: The in vivo assessment of the three-dimensional kinematics of the hip during dance activities in patients after total hip arthroplasty has not been previously reported. We evaluated the replaced hip kinematics during recreational classical ballet and hula dance using radiographic-based image-matching techniques.

Case Presentation: A 58-year-old Japanese woman (patient 1; height, 157 cm; weight, 74.

Does high hip centre affect dislocation after total hip arthroplasty for developmental dysplasia of the hip?

Background: To achieve sufficient socket coverage by the native bone, high placement of cementless acetabular cup is often required. We previously reported, using computer simulation, that higher hip centre improved the bone coverage but decreased the range of motion in total hip arthroplasty (THA) for patients with hip dysplasia. However, in a clinical setting, the correlation between the hip centre height and dislocation after primary THA is still unclear.

How does anteroposterior cup placement affect bone coverage and range of motion in primary total hip arthroplasty for hip dysplasia?

Background: Due to anterior bone defects, high and/or posterior placement of an acetabular cup is often required to achieve sufficient coverage in patients with hip dysplasia. We examined whether posterior cup placement affected the postoperative range of motion (ROM) in primary total hip arthroplasty (THA).

Methods: Using computer software, bone coverage and ROM were examined in 32 patients with unilateral osteoarthritis of the hip with Crowe type II or III hip dysplasia.

Dynamic hip kinematics during squatting before and after total hip arthroplasty.

Background: The difference in in vivo kinematics before and after total hip arthroplasty (THA) for the same subjects and the clearance between the liner and neck during squatting have been unclear. The purpose of the present study was to clarify (1) the changes in the in vivo kinematics between prosthetic hips and osteoarthritis hips of the same subjects and (2) the extent of the liner-to-neck clearance during squatting under weight-bearing conditions.

Methods: This study consisted of 10 patients who underwent unilateral THA for symptomatic osteoarthritis.

Sports Participation in Patients After Total Hip Arthroplasty vs Periacetabular Osteotomy: A Propensity Score-Matched Asian Cohort Study.

Background: No studies have compared sports participation between total hip arthroplasty (THA) and periacetabular osteotomy (PAO) in matched Asian cohorts. We investigated sports participation and activity levels in Asian THA cohort, and compared them between THA and PAO cohorts.

Methods: Multivariate analyses were applied to determine which factors were associated with postoperative sports participation and University of California-Los Angeles (UCLA) activity score in (1) 524 THA patients and (2) 487 acetabular dysplasia patients (295 THA patients and 192 PAO patients).

Does Participation in Sports Affect Osteoarthritic Progression After Periacetabular Osteotomy?

Background: Periacetabular osteotomy (PAO) is an effective treatment for symptomatic acetabular dysplasia. However, whether postoperative participation in sports leads to progression of the Kellgren-Lawrence (KL) grade of osteoarthritis (OA) in these patients is unclear.

Purpose: To investigate (1) participation in sports before and after PAO and (2) whether postoperative participation in sports leads to progression of the KL grade.

Does High Hip Center Decrease Range of Motion in Total Hip Arthroplasty? A Computer Simulation Study.

Background: High placement of a cementless acetabular cup is often required to have sufficient bone coverage in hip dysplasia. We examined whether a high hip center decreases the postoperative range of motion (ROM) in total hip arthroplasty.

Methods: Using a computer software, ROM and bone coverage were examined in 32 patients with unilateral osteoarthritis of the hip with Crowe type II or III hip dysplasia.

The Absence of Hydroxyapatite Coating on Cementless Acetabular Components Does Not Affect Long-Term Survivorship in Total Hip Arthroplasty.

Background: Hydroxyapatite (HA) has been applied to joint prostheses as a bioactive coating to prolong their durability. However, HA benefits for cup survival in total hip arthroplasty (THA) remain controversial. In this study, we compared the survival of cups with and without HA coating during a minimum follow-up of 18 years.

Recurrent dislocations of the atlantooccipital and atlantoaxial joints in a halo vest fixator are resolved by backrest elevation in an elevation angle-dependent manner.

Background Context: Halo fixation is now universally performed in the initial reduction and fixation of unstable upper cervical spine injuries; however, persistent high instability and recurrent dislocations of the atlantooccipital and atlantoaxial joints after fixation are not well recognized.

Purpose: The aim was to describe persistent instability of traumatic dislocations of the atlantooccipital and atlantoaxial joints after halo fixation and a useful method for preventing instability.

Study Design: This was a case report of a patient who survived traumatic dislocations of the atlantooccipital and atlantoaxial joints.