Comparison study of bone strength of the proximal femur with and without hip osteoarthritis by computed tomography-based finite element analysis.

Proximal femoral fractures are common in elderly osteoporosis patients; however, its prevalence is clinically rare in hip fracture patients with hip osteoarthritis (OA). This study aimed to evaluate bone strength of the proximal femur with or without hip OA and proximal femoral fracture risk using computed tomography (CT)-based finite element analysis (FEA). A retrospective analysis was done on CT data of 20 patients who underwent total hip arthroplasty for unilateral hip OA. Furthermore, the fracture load between OA and contralateral sides was compared and the association between fracture load and risk factor was analyzed. The fracture load was significantly higher in the OA side than that in the contralateral side (3819.5 ± 1557.8 N vs. 3224.5 ± 943.7 N, respectively; P = 0.0405). There was no significant difference in fracture load between OA and the contralateral side in Kellgren-Lawrence (KL)-3 and KL-4 grade, but the KL-4 fracture load tends to be high (P = 0.2461 and P = 0.0527, respectively). Moreover, there was no significant association between fracture load and OA severity or age. The study findings may assist in predicting bone strength and proximal femur fracture risk. The results of this FEA study indicate the bone strength of the proximal femur was affected by the severity of the osteoarthritis.

Predictive value of magnetic resonance imaging for multifocal osteonecrosis screening associated with glucocorticoid therapy.

Objectives: The goals of this study were to elucidate the distribution of multifocal osteonecrosis associated with glucocorticoid therapy using magnetic resonance imaging (MRI) and to establish a MRI screening method.Methods: Between 1986 and 2018, 107 patients underwent MRI screening of their hips, knees, shoulders and ankle joints (856 joints in total) after systemic glucocorticoid therapy.Results: Osteonecrosis was observed in hip (68%), knee (44%), ankle (17%) and shoulder (15%) joints. Patients with bilateral osteonecrosis in their hips were likely to have bilateral osteonecrosis in their knees, whereas patients without osteonecrosis in both hips were unlikely to have osteonecrosis in both knees (p = .0299). Osteonecrosis was never evident in the ankle or shoulder joints when a patient did not have osteonecrosis in both hip and knee joints.Conclusion: In this study, MRI - as a screening method for multifocal osteonecrosis associated with glucocorticoid therapy - showed the sites affected first are hips and knees followed by ankles and shoulders. If osteonecrosis is absent in hip and knee joints, further screening of the ankles and shoulders is unnecessary. Any osteonecrosis observed in the hip and/or the knee joints warrants a second MRI screening of the ankles and shoulders.

Ratio of dislocation types of the proximal interphalangeal joint of the fingers: A new classification system for initial therapy.

BACKGROUND: We proposed a new system named the sagittal, coronal, axial, rotational and fracture (SCARF) classification, which can simply explain any condition of proximal interphalangeal (PIP) joint dislocations of the fingers. The purpose of this study was to verify that this classification would contribute to management of PIP joint dislocations at the initial therapy. We determined ratios of five factors in PIP dislocations with SCARF by interpreting radiographs and assessed the interobserver and intraobserver variability. METHODS: In total, 68 fingers in 67 consecutive patients were studied. The SCARF classification is composed of five factors: (1) sagittal plane displacement is rated by dorsal (D), volar (V), or neutral (N); (2) coronal plane displacement, by ulnar (U), radial (R), or neutral (N); (3) axial force, by compression (C), traction (T), or no (N); (4) rotational displacement, by supine (S), prone (P), or neutral (N); and (5) fracture concomitance, by minus (-) or plus (+). The row of the five characters explains each condition of PIP joint dislocations. Interobserver and intraobserver variability was determined after six orthopedic surgeons independently classified the same radiographs twice. RESULTS: All 68 dislocations were classified into 14 types, unless fracture concomitance was considered. The most common type was DUNN (35%). In coronal plane displacements, the two ulnar fingers showed a higher tendency to the ulnar position. Ring finger fracture concomitance was higher than in middle fingers or little fingers. In interobserver analysis, mean kappa coefficient for each factor was 0.63, 0.75, 0.68, 0.33, and 0.84, respectively. In intraobserver analysis, that was 0.73, 0.79, 0.71, 0.41, and 0.81, respectively. CONCLUSIONS: Even other than hand specialists can specify the type of every PIP dislocation by using the SCARF classification and will have better understanding of the disorder. It would contribute to management of PIP dislocations at the initial therapy. TYPE OF STUDY/LEVEL OF EVIDENCE: Diagnostic II.

Diffusion tensor imaging of the sciatic and femoral nerves in unilateral osteoarthritis of the hip and osteonecrosis of femoral head: Comparison of the affected and normal sides.

Objective: The aim was to compare the fractional anisotropy (FA) and apparent diffusion coefficient (ADC) values of the sciatic and femoral nerves in patients with unilateral osteoarthritis of the hip (OA) and osteonecrosis of the femoral head (ONFH) using diffusion tensor imaging (DTI) and to investigate the mechanism of hip pain. Methods: Forty-four patients (22 OA and 22 ONFH) underwent DTI of the sciatic and femoral nerves at the level of the hip joint and the S1 roots to visualize the tractography and quantify the FA and ADC values. Results: The tractography of the femoral and the sciatic nerves on the affected side with OA and ONFH were similar to those on the normal side. The mean FA values of the sciatic and femoral nerves, and the S1 roots were 0.542, 0.551, and 0.316 with OA, 0.568, 0.560, and 0.318 with ONFH on the affected side, and 0.559, 0.560, and 0.315 on the normal side, respectively, and did not show significant differences. The FA values of the sciatic nerve on the affected side with OA decreased with longer pain duration. Conclusion: The FA and ADC values of the sciatic and femoral nerves in patients with unilateral OA and ONFH showed no significant differences between the affected and normal sides.

Finite element analysis of the femoral diaphysis of fresh-frozen cadavers with computed tomography and mechanical testing.

BACKGROUND: The purpose of this study was to validate a diaphyseal femoral fracture model using a finite element analysis (FEA) with mechanical testing in fresh-frozen cadavers. METHODS: We used 18 intact femora (9 right and 9 left) from 9 fresh-frozen cadavers. Specimens were obtained from 5 males and 4 females with a mean age of 85.6 years. We compared a computed tomography (CT)-based FEA model to diaphyseal femoral fracture loads and stiffness obtained by three-point bending. Four material characteristic conversion equations (the Keyak, Carter, and Keller equations plus Keller's equation for the vertebra) with different shell thicknesses (0.3, 0.4, and 0.5 mm) were compared with the mechanical testing. RESULTS: The average fracture load was 4582.8 N and the mean stiffness was 942.0 N/mm from actual mechanical testing. FEA prediction using Keller's equation for the vertebra with a 0.4-mm shell thickness showed the best correlations with the fracture load (R2 = 0.76) and stiffness (R2 = 0.54). Shell thicknesses of 0.3 and 0.5 mm in Keller's equation for the vertebra also showed a strong correlation with fracture load (R2 = 0.66 for both) and stiffness (R2 = 0.50 and 0.52, respectively). There were no significant correlations with the other equations. CONCLUSION: We validated femoral diaphyseal fracture loads and stiffness using an FEA in a cadaveric study.

Anatomical Features of the Descending Genicular Artery to Facilitate Surgical Exposure for the Subvastus Approach-A Cadaveric Study.

BACKGROUND: The purpose of this cadaveric study was to clarify the proximal limit for the subvastus approach (SVA) in total knee arthroplasty to decrease potential vascular injury. METHODS: Seventy embalmed knees underwent a modified SVA using a 14-cm oblique medial incision. Anatomical features of the descending genicular artery (DGA) were investigated with regard to variation, distance of the vessels from surgical landmarks, and sex differences. RESULTS: The DGA was identified in 62 knees (89%), while it was absent in 8 knees (11%); in the latter, the articular, saphenous, and muscular branches arose separately from the femoral artery. The mean distances from the tibial tuberosity and medial joint line to the origin of the DGA were 15.5 ± 1.6 cm and 12.6 ± 1.6 cm, respectively. Both distances were significantly longer in males than in females (P < .01, respectively). A strong positive correlation was found between the distance from the tibial tuberosity to the origin of the DGA and the distance from the medial joint line to the origin of the DGA (Spearman's correlation coefficient, R2 = 0.72, P < .01). A weak positive correlation was found between the distance from the tibial tuberosity to the origin of the DGA and lower leg length (R2 = 0.13, P < .01). No vascular injuries were observed in this surgical exposure. CONCLUSION: The DGA showed several variations and was absent 11% of the time. An oblique medial incision within 14 cm from the tibial tuberosity followed by arthrotomy is considered a safe zone for the SVA.

Transitional changes in the incidence of osteonecrosis in systemic lupus erythematosus patients: focus on immunosuppressant agents and glucocorticoids.

Objective: The purpose of this study was to investigate transitional changes in the incidence of glucocorticoid-associated osteonecrosis in SLE patients, with a focus on immunosuppressive agent and glucocorticoid consumption. Methods: We retrospectively registered 185 SLE patients with 740 joints, who were newly diagnosed and hospitalized for initial high-dose glucocorticoid therapy from 1986 to 2015. Immunosuppressive agent, glucocorticoid dose, age, sex, organ lesion at hospitalization, complement (C3, C4, CH50) and anti-DNA antibody before initial glucocorticoid therapy, the frequency of use of anticoagulant and antilipidemic drugs, and incidence of osteonecrosis were documented. Results: Based on trends in immunosuppressive agent use, 116 patients treated from 1986 to 1999, before calcineurin inhibitors were introduced, comprised the past group, and 69 patients treated from 2000 to 2015 comprised the recent group. Patient characteristics (age, sex and organ lesion at hospitalization, complement, anti-DNA antibody, the frequency of use of anticoagulant and antilipidemic drugs) were similar between groups. Glucocorticoid doses were significantly lower in the recent group than in the past group (highest daily glucocorticoid dose, 45.7 vs 59.0 mg/day, respectively; dose per weight, 0.88 vs 1.16 mg/day/kg, respectively; and cumulative dose at 3 months, 3118 vs 3985 mg). The incidence of osteonecrosis was significantly lower in the recent group than in the past group (26.4 vs 41.0%, respectively), particularly in the knee (25.4 vs 46.6%, respectively). Conclusion: The incidence of glucocorticoid-associated osteonecrosis in SLE patients decreased in association with a decrease in glucocorticoid administration after introduction of immunosuppressant agents.

Interobserver and Intraobserver Reliability of Computed Tomography-Based Three-Dimensional Preoperative Planning for Primary Total Knee Arthroplasty.

BACKGROUND: Preoperative planning is an important factor for total knee arthroplasty (TKA). The aim of this study is to document the interobserver and intraobserver reliability of computed tomography (CT)-based 3-dimensional (3D) preoperative planning for primary TKA. METHODS: Twenty knees (10 with osteoarthritis and 10 with rheumatoid arthritis) were studied independently by 6 orthopedic surgeons using a CT-based 3D planning system. The measurements were made twice at more than 3-week intervals without any knowledge of their own previous measurements or those of the others. We assessed the femoral and tibial component sizes and the alignment of the femoral component. RESULTS: The interobserver and intraobserver agreements for femoral component size were 44.3% and 62.5% with exact size, and increased to 90.7% and 99.2% within one size difference; the intraclass correlation coefficients (ICCs) were 0.919 and 0.936, respectively. The interobserver and intraobserver agreements for tibial component size were 57.0% and 66.7% with exact size, and increased to 87.3% and 90.0% within one size difference; the ICCs were 0.909 and 0.924, respectively. The ICCs for femoral and tibial size were better in rheumatoid arthritis than in osteoarthritis. Interobserver ICC for femoral valgus angle was 0.807, and 0.893 for intraobserver reliability. Interobserver ICC of the femoral external rotation angle was 0.463, and 0.622 for intraobserver reliability. CONCLUSION: CT-based 3D preoperative planning for primary TKA has clinical implications for predicting appropriate size and alignment of the component in patients with osteoarthritis and rheumatoid arthritis.

Interobserver and Intraobserver Reliability of Three-Dimensional Preoperative Planning Software in Total Hip Arthroplasty.

BACKGROUND: The purpose of this study is to clarify interobserver and intraobserver reliabilities of the three-dimensional (3D) templating of total hip arthroplasty (THA). METHODS: We selected preoperative computed tomography from 60 hips in 46 patients (14 men and 32 women) who underwent primary THA. To evaluate interobserver and intraobserver reliability, 6 orthopedic surgeons performed 3D templating twice over a 4-week interval. We investigated intraclass correlation coefficients (ICCs) and percent agreement of component size and alignment, comparing morphological differences in the hip. Reproducibility was also compared between groups with osteoarthritis (OA) and those with osteonecrosis (ON). RESULTS: The interobserver reliabilities for mean cup size and stem size were excellent, with ICC = 0.907 and 0.944, respectively. The value was significantly higher in the ON group than in the OA group. In the OA group, the reliability of cup size and alignment decreased in hips with severe subluxation. Percent agreement of stem size was significantly different between the shapes of femoral canal. For intraobserver reliability, the mean ICC of cup size was 0.965 overall, while the value in the ON group was significantly higher than in the OA group. The mean ICC of stem size was 0.972 overall. CONCLUSION: Computed tomography-based 3D templating showed excellent reliability for component size and alignment in THA. Deformity of the affected joint influenced the reliability of preoperative planning.

Diffusion tensor imaging and tractography of the sciatic and femoral nerves in healthy volunteers at 3T.

BACKGROUND: The aim was to clarify the normal fractional anisotropy (FA) and apparent diffusion coefficient (ADC) values of the sciatic and femoral nerves at the level of the hip joint and to visualize the neural tracts with diffusion tensor imaging (DTI). METHODS: Twenty-four healthy volunteers (12 men and 12 women, age 20-29 years) underwent DTI for visualization with tractography and quantification of FA and ADC values on a 3 Tesla MRI (b value = 800 s/mm2, motion probing gradient, 11 directions, time to repeat/echo time = 9000/72.6 ms, axial slice orientation, slice thickness = 3.0 mm with no inter-slice gap, field of view = 320 × 320 mm, 96 × 192 matrix, 75 slices, number of acquisitions = 4). Regions of interest in the sciatic nerve were defined at the femoral head, the S1 root, and the midpoint levels. The femoral nerve was evaluated at 3-4 cm proximal to the femoral head level. RESULTS: The tractography of the sciatic and femoral nerves were visualized in all participants. The mean FA values of the sciatic nerve were increased distally from the S1 root level, through the midpoint, and to the femoral head level (0.314, 0.446, 0.567, p = 0.001, respectively). The mean FA values of the femoral nerve were 0.565. The mean ADC values of the sciatic nerves were significantly lower in the S1 root level than in the midpoint and the femoral head level (1.481, 1.602, 1.591 × 10-3 × 10-3 mm2/s, p = 0.001, respectively). The ADC values of the femoral nerve were 1.439 × 10-3 mm2/s. FA and ADC values showed moderate to substantial inter- and intra-observer reliability without significant differences in gender or laterality. CONCLUSION: Visualization and quantification of the sciatic and femoral nerves simultaneously around the hip joint were achieved in healthy young volunteers with DTI. Clinical application of DTI is expected to contribute to hip pain research.

Prediction of fracture load and stiffness of the proximal femur by CT-based specimen specific finite element analysis: cadaveric validation study.

BACKGROUND: Finite element analysis (FEA) of the proximal femur has been previously validated with large mesh size, but these were insufficient to simulate the model with small implants in recent studies. This study aimed to validate the proximal femoral computed tomography (CT)-based specimen-specific FEA model with smaller mesh size using fresh frozen cadavers. METHODS: Twenty proximal femora from 10 cadavers (mean age, 87.1 years) were examined. CT was performed on all specimens with a calibration phantom. Nonlinear FEA prediction with stance configuration was performed using Mechanical Finder (mesh,1.5 mm tetrahedral elements; shell thickness, 0.2 mm; Poisson's coefficient, 0.3), in comparison with mechanical testing. Force was applied at a fixed vertical displacement rate, and the magnitude of the applied load and displacement were continuously recorded. The fracture load and stiffness were calculated from force-displacement curve, and the correlation between mechanical testing and FEA prediction was examined. RESULTS: A pilot study with one femur revealed that the equations proposed by Keller for vertebra were the most reproducible for calculating Young's modulus and the yield stress of elements of the proximal femur. There was a good linear correlation between fracture loads of mechanical testing and FEA prediction (R2 = 0.6187) and between the stiffness of mechanical testing and FEA prediction (R2 = 0.5499). There was a good linear correlation between fracture load and stiffness (R2 = 0.6345) in mechanical testing and an excellent correlation between these (R2 = 0.9240) in FEA prediction. CONCLUSIONS: CT-based specimen-specific FEA model of the proximal femur with small element size was validated using fresh frozen cadavers. The equations proposed by Keller for vertebra were found to be the most reproducible for the proximal femur in elderly people.