Age-related differences in morphology and kinematics of the native hip.

Our objectives were to clarify morphology of the hip as well as infinitesimal femoral head movement in specific positions in young and elderly volunteers without joint degeneration. Both hips of 20 young and 20 elderly healthy volunteers were examined. Magnetic resonance imaging was performed at four different positions for each hip: neutral, 45° flexion, 15° extension, and the Patrick position.

Influence of femoral bowing on range of motion after total hip arthroplasty.

Purpose: The influence of physiologic femoral bowing on range of motion (ROM) after total hip arthroplasty (THA) remains unknown. The purpose of this study was to investigate the morphology of the femur in patients who underwent THA, and to analyze the influence of femoral bowing on ROM due to implant impingement after THA.

Methods: The ROM was calculated from 100 hips in 90 patients who underwent THA using computed tomography data with a 3D dynamic analysis software.

Chronological Changes in Axial Alignment of the Ipsilateral Hip and Knee After Total Hip Arthroplasty.

Background: Internal rotation of the hip and lateral patellar tilt increases after total hip arthroplasty (THA). However, it remains unknown whether these parameters change with time after the index THA.

Methods: A total of 91 patients undergoing 2-stage bilateral primary THAs between January 2008 and May 2014 were included to assess the association of chronological changes in internal rotation of the hip or lateral patellar tilt with anthropometric and perioperative parameter and changes in alignment after the index THA.

Morphological analysis of the acetabular cartilage surface in elderly subjects.

Purpose: The geometry of acetabular cartilage surface plays an important role in hip joint biomechanics. The aim of this study was to analyze the morphology of acetabular articular cartilage surface in elderly donated bodies to science using a 3D-digitizer.

Methods: Twenty hemipelves from 12 subjects (mean ages 85 years) were scanned with 3D-digitizer.

In vivo hip joint contact distribution and bony impingement in normal and dysplastic human hips.

Our objectives were to clarify the 3D articular contact areas of the in vivo normal hip joint and acetabular dysplasia during specific positions using magnetic resonance imaging (MRI), voxel-based registration, and proximity mapping. Forty-two normal and 24 dysplastic hips were examined. MRI was performed at four positions: neutral; 45° flexion; 15° extension; and the Patrick position.

Verification of the Robin and Graham classification system of hip disease in cerebral palsy using three-dimensional computed tomography.

Aim: We evaluated the validity of the Robin and Graham classification system of hip disease in cerebral palsy (CP) using three-dimensional computed tomography in young people with CP.

Method: A total of 91 hips in 91 consecutive children with bilateral spastic CP (57 males, 34 females; nine classified at Gross Motor Function Classification System level II, 42 at level III, 32 at level IV, and eight at level V; mean age 5 y 2 mo, SD 11 mo; range 2-6 y) were investigated retrospectively using anteroposterior plain radiographs and three-dimensional computed tomography (3D-CT) of the hip. The migration percentage was calculated on plain radiographs and all participants were classified into four groups according to migration percentage: grade II, migration percentage ≥ 10% but ≤ 15%, (four hips), grade III, migration percentage >15% but ≤ 30%, (20 hips); grade IV, migration percentage >30% but <100%, (63 hips); and grade V, migration percentage ≥ 100%, (four hips).

In vivo kinematic analysis of squatting after total hip arthroplasty.

Background: The in vivo kinematics of squatting after total hip arthroplasty is unclear. The purpose of the present study was to determine the range of motion of the hip joint during squatting after total hip arthroplasty.

Methods: Using fluoroscopy, we investigated 15 primary cementless total hip arthroplasties performed using a computed tomography-based navigation system.