Factors associated with functional limitations in the daily living activities of Japanese hip osteoarthritis patients.

AIM: As society ages, there is a vast number of elderly people with locomotive syndrome. In this study, the factors associated with functional limitations in daily living activities evaluated by female hip osteoarthritis (OA) patients were investigated. METHODS: This study was a cross-sectional study. The subjects were 353 female patients who were newly diagnosed with hip OA at an orthopedic clinic with no history of hip joint surgery. Outcome indices were functional limitations in two daily living activities obtained from a questionnaire completed by the patients: (i) standing up (standing from a crouched position) and (ii) stair-climbing (climbing and/or descending stairs). The odds ratios (ORs) and 95% confidence intervals (CIs) were computed for explanatory variables using the proportional odds model in logistic regression to evaluate their associations with functional limitations. RESULTS: Functional limitations in standing up were associated with heavy weight (third tertile vs. first tertile: 1.91, 1.11-3.27), participation in sports at school (0.62, 0.40-0.98), parity (vs. nullipara: 1.96, 1.08-3.56), old age and OA stage. Associations with functional limitations in stair-climbing were seen with short height (< 151.0 cm vs. ≥ 156.0 cm: 2.05, 1.02-4.12), bilateral involvement (vs. unilateral: 1.71, 1.01-2.88), old age and OA stage. CONCLUSION: Old age, OA stage, heavy weight, parity, shorter height and bilateral OA were associated with functional limitations in standing up and/or stair-climbing, whereas participation in sports such as club activities in school maintained standing up.

Factors associated with diagnostic stage of hip osteoarthritis due to acetabular dysplasia among Japanese female patients: a cross-sectional study.

BACKGROUND: In Japan, the majority of hip osteoarthritis (OA) was caused by acetabular dysplasia, and about 90 % of patients were female. The present study focused on Japanese female patients with hip OA due to acetabular dysplasia, and examined the associated factors with OA staging at diagnosis, in special reference to body weight. METHODS: Study subjects were 336 Japanese women who were newly diagnosed with hip OA caused by acetabular dysplasia at 15 hospitals in 2008. The self-administered questionnaire elicited patients' body weight at age 20 and at OA diagnosis. Four ranked OA staging according to radiographic findings of the hip joint (pre-OA, initial stage, advanced stage or terminal stage) was regarded as the outcome index. Proportional odds models in logistic regression were used to calculate odds ratios (ORs) and 95 % confidence intervals (CIs) for severer stage of OA. RESULTS: At diagnosis, 45 % of patients suffered from terminal stage of OA, whereas 13 % and 14 % were categorized into pre-OA and initial stage, respectively. After adjustment for potential confounders, weight gain since age 20 revealed the increased ORs for severer OA stage at diagnosis (OR 2.02; 95 % CI, 1.07-3.80). Other significant characteristics were age (67+ vs. 20-49 years, OR 12.4), lower education (junior high school vs. junior college or higher, OR 4.00), parity (OR 2.19), lower acetabular head index (<60.0 vs. 71.1+, OR 2.36), and longer duration since symptom onset (6.0+ vs. <1.0 year, OR 2.94). CONCLUSIONS: Weight gain since age 20 might be involved in mechanisms of OA development, which is independent of age or severity of acetabular dysplasia.

4. The Low-Intensity Pulsed Ultrasound (LIPUS) Mechanism and the Effect of Teriparatide on Fracture Healing.

Low-Intensity Pulsed Ultrasound (LIPUS) provided a mechanical stimulus, and was thought to promote fracture healing by signal transduction through integrin, a cytoskeletal protein. Meanwhile, teriparatide, a drug for osteoporosis treatment, showed efficacy in promoting bone metabolism. This drug also appeared to prevent fractures in patients with serious osteoporosis by improving bone mineral density and bone quality, which in turn resulted from promoting action for bone metabolism. Further, clinical trials and fundamental research reported that teriparatide demonstrated the effect of promoting fracture healing. Mechanical stimulus by LIPUS had a topical effect on fractures; on the other hand, teriparatide (peptide hormone) had both topical and systemic effects. Both LIPUS and teriparatide had the effect of fracture healing, but it was supposed that the characteristics of each effect were different because of the different mechanism of action. Moreover, the combination therapy of LIPUS and teriparatide was expected to produce synergies. We used elderly rats as models for the femoral fracture to examine the effects of LIPUS and teriparatide on promoting fracture healing for treatment delay by aging. We observed the fracture healing process in 40-week-old rats as an elderly model using simple radiographs, and recognized a delay in fracture healing compared with that of 8-week-old rats. As discussed in histomorphology, it was demonstrated that the period of endochondral ossification, from chondrogenesis to teleost cross-linked callus, was prolonged and the fracture healing process was delayed by aging. Next, we treated the elderly fracture models with LIPUS for 20 minutes a day from the first day after the fracture, and compared them with non-treated models. The bone unions of the treated models were observed earlier than those of non-treated models in the simple radiographs. LIPUS shortened the period of endochondral ossification. Further, we gave the elderly fracture models teriparatide subcutaneously 5 µg/kg three times a week from the first day after the fracture. Bone unions of the treated models were observed earlier than those of non-treated models in simple radiographs as well. In micro CT analysis, it was demonstrated that lamellar bone transforming and bone remodeling of the trabecular structure of external callus were especially accelerated. The results of these trials showed that both LIPUS and teriparatide demonstrated the effect of promoting fracture healing, and each had unique characteristics.

12. Influence of Wound Dressing on the Fracture Healing Effect of Low-Intensity Pulsed Ultrasound (LIPUS).

OBJECTIVE: We have conducted a basic study on the influences on ultrasonic properties when LIPUS is applied through wound dressing. According to the results of ex vivo experiments conducted to date, LIPUS showed ultrasonic properties such as transmittance, coefficient of transmission, and a non-uniformity ratio through film wound dressing better than other wound dressing, and it was considered that LIPUS's effect for fracture healing was not influenced by film wound dressing. Then, we discussed the influence on the effect of LIPUS through film wound dressing. METHODS: Thirty male 8-week-old Sprague-Dawley rats were used for the trial. After creating close transverse femoral fractures on the right legs of these 30 rats, they were divided into 3 groups of 10; LIPUS through wound dressing (Group A), LIPUS without wound dressing (Group B), and No LIPUS treatment (Group C). OPSITE Wound, which was thought to have the least influence on ultrasound properties, was used for this trial. Group A and B received LIPUS for 20 minutes a day from the first day after the fractures. LIPUS was generated from Teijin Pharma's device for a basic experiment. When treating Group A, the wound dressing was pasted on the ultrasound terminal in order to apply LIPUS through the dressing. We assessed the time-oriented morphological change of each group in anesthetized condition using simple radiographs on the 8th, 16th, and 24th day after the fractures. RESULTS: Six rats in Group A, 2 in Group B, and 1 in Group C died in anesthesia, and we discussed the remaining 4 rats in Group A, 8 in Group B, and 9 in Group C. We defined more than one teleost callus bridging as bone-union. We also counted a bone remodeling when we recognized the absorption of existing cortical bone and the transformation of new bone to cortical bone in simple radiographs. As a result, compared with Group C, we recognized that both bone union and remodeling accelerated remarkably in Group B, but not in Group A. DISCUSSION: It suggested that LIPUS through wound dressing had negative influences on both period shorting of fracture healing and bone remodeling. When LIPUS was conducted through film wound dressing, transmittance and coefficient of transmission were unchanged; however, the non-uniformity ratio changed slightly. The non-uniformity ratio of the ultrasound transducer had a significant influence on the effect of LIPUS on fracture healing.

Prevalence of radiographic findings of femoroacetabular impingement in the Japanese population.

BACKGROUND: Femoroacetabular impingement (FAI) is one factor known to cause pain and osteoarthritis (OA) of the hips. Although secondary OA due to hip dysplasia is common among Japanese populations, primary OA is seldom observed. Concomitantly, FAI is also thought to be uncommon in Japan, but relatively few epidemiological studies have addressed this issue. This study aimed to clarify the prevalence of radiographic findings of FAI in a Japanese population and to evaluate whether FAI is a risk factor for the development of arthritic changes. METHODS: We retrospectively examined 87 patients who underwent unilateral hip osteotomy with a Charnley category A hip joint on the contralateral side. Anteroposterior-view radiographs of the non-operated hip joint were assessed for the presence of hip dysplasia, as well as pistol grip deformity and crossover sign indicative of cam-type and pincer-type impingement, respectively. The presence of arthritic changes in the non-operated hip joint was assessed in follow-up radiographs, and factors contributing to the development of arthritis were determined by survival analysis. RESULTS: Of the 87 hips examined, dysplasia was noted in 38 (43.6%). While no pistol grip deformity was observed, crossover sign, which is indicative of pincer-type impingement, was identified in 9 of 38 dysplastic hips (23.7%) and 15 of 49 non-dysplastic hips (30.6%). Arthritic changes were present in 13 of 38 dysplastic hips (34.2%) and 11 of 49 non-dysplastic hips (22.4%). Survival analysis revealed that the presence of the crossover sign in non-dysplastic hips was significantly associated with the development of arthritis. CONCLUSIONS: The prevalence of the crossover sign in hips in a Japanese population is similar to that reported in Western populations, despite the fact that FAI is believed to be less prevalent in the Japanese population. Furthermore, the presence of the crossover sign in non-dysplastic hip joints is associated with the development of arthritis. Based on our results, pincer-type impingement could be commonly associated with the development of arthritis in Japanese populations.

Relationship of acetabular dysplasia in females with osteoarthritis of the hip to the distance between both anterior superior iliac spines.

BACKGROUND: Acetabular dysplasia (AD) is the main cause of hip osteoarthritis in Japan. A simple method to evaluate acetabular dysplasia would be helpful for early treatment or prevention of hip osteoarthritis. Acetabular dysplasia is reported to be associated with pathological transverse growth of the pelvis, indicating that the distance between the 2 anterior superior iliac spines might be useful for screening and detection of acetabular dysplasia. The purpose of this study was to determine if the acetabular dysplasia radiographic parameters are related to the distance between the 2 anterior superior iliac spines in patients with hip osteoarthritis. MATERIAL AND METHODS: In this study, data obtained in a previous multi-institutional examination of patients with hip osteoarthritis in Japan were evaluated. The anterior superior iliac spine distances of 176 female patients (mean age, 54 years; range, 18-85 years) were measured by physical examination. The relationship between the anterior superior iliac spine distance and acetabular dysplasia was analyzed, and the anterior superior iliac spine distances of the patients with acetabular dysplasia who were at relatively high risk for hip osteoarthritis were compared with that of the patients at lower risk. RESULTS: A statistically significant relationship between the anterior superior iliac spine distance and all of the acetabular dysplasia parameters was observed. The anterior superior iliac spine distances of the acetabular dysplasia patients with a relatively high risk for radiographic acetabular dysplasia parameters were significantly smaller than those of patients at lower risk. Even after adjustment for age, height, and weight, significantly increased relative risk for having high risk AD was found in patients with an ASIS distance of less than 24.5 cm. CONCLUSIONS: There was a significant relationship between the anterior superior iliac spine distance and the degree of acetabular dysplasia.

Revision total hip arthroplasty using an interlocking stem with an allograft-prosthesis composite.

We report the clinical and radiographic outcomes and complications of revision surgery using a cementless interlocking stem with an allograft-prosthesis composite (APC). This study included 11 patients with an average follow-up of 73 years. Of the 11 revisions, 1 was aseptic, 7 were septic, and 3 were periprosthetic femoral fractures. The mean Harris hip score improved from 25.6 points before surgery to 74.8 points at final follow-up. Osseous union at the proximal allograft-host bone junction occurred in 10 hips (90.9%) ; the greater trochanter did not unite in 4 of 7 hips (57.1%). Moderate and severe allograft resorption occurred in one hip each. Postoperative complications included 1 deep infection, 2 heterotopic ossifications, and 1 dislocation. Using an interlocking stem with an allograft-prosthesis composite in revision surgery provided acceptable results in the presence of circumferential massive bone deficiency of the proximal femur.

Two-stage revision total hip arthroplasty for periprosthetic infections using antibiotic-impregnated cement spacers of various types and materials.

Antibiotic-impregnated hip cement spacers of various types and materials have been used in the treatment of periprosthetic hip infections. We developed a handmade spacer by using polymethylmethacrylate (PMMA) and/or α -tricalcium phosphate ( α -TCP). In this study, we retrospectively reviewed the surgical outcomes in 36 consecutive patients treated with 2-stage revision total hip arthroplasty by using our antibiotic-impregnated hip cement spacers. We aimed to analyze the infection control and reinfection rates after revision surgery. Moreover, we analyzed the possible predictors of postoperative reinfection. After exclusion of 1 patient who died immediately after the first-stage surgery, infection was controlled in 33 of the 36 hips (success rate, 91.7%). Two of these 33 hips underwent resection arthroplasty. Of the 36 hips that had been treated with the antibiotic-cement spacer, 31 hips (86.1%) were eligible for the second-stage prosthesis re-implantation. The 31 protocol hip joints of patients followed up for >6 months (mean, 48.6 months). Ten of these 31 hips (32.3%) became reinfected. No possible predictor examined differed significantly between the reinfection-positive and reinfection-negative groups. However, spacers consisting of PMMA cement alone were associated with the highest risk of reinfection. Therefore, α -TCP-containing antibiotic-impregnated hip cement spacers might decrease the reinfection rate in patients undergoing re-implantation.

Bone marrow-engrafted cells after mice umbilical cord blood transplantation differentiate into osteoblastic cells in response to fracture and placement of titanium screws.

As the in vivo function of bone marrow-engrafted umbilical cord blood (UCB)-derived mesenchymal cells (UCBCs) after UCB transplantation is unknown, we examined in vivo osteoblastic differentiation using mouse UCB transplantation and fracture models. UCBCs obtained from GFP transgenic mice were intravenously injected into irradiated C57BL/6 mice. After three months, the in vivo osteoblastic differentiation potential of bone marrow-engrafted UCBCs was examined histologically using a mouse fracture model. GFP-positive UCBCs were detected in the bone marrow of recipient mice. On day 7, UCBCs were observed in the fracture gap and surrounding the titanium screws of the fixation device. The UCBCs were also positive for alkaline phosphatase and von Kossa staining. By day 14, UCBCs were observed around and within a formed intramedullary callus. The newly formed woven bone consisted of ALP- and von Kossa-positive cells. Our findings suggest that UCBCs contribute to the fracture healing process after bone marrow engraftment and that UCBC transplantation can fully reconstruct not only hematopoietic cells but also mesenchymal cell lineages.

Evaluation of bipolar hemiarthroplasty for the treatment of steroid-induced osteonecrosis of the femoral head.

PURPOSE: Bipolar hemiarthroplasty (BHA) for idiopathic osteonecrosis of the femoral head (ONFH) is performed at our institution. The purpose of this study was to evaluate the clinical and radiographic findings after BHA for the treatment of steroid -induced ONFH. METHODS: Thirty-seven hips in 27 patients were assessed (seven men, 11 hips; 20 women, 26 hips), average patient age at the time of surgery of 42.6 (range 20-83) years, with steroid-induced ONFH treated with BHA between 1995 and 2005. The mean follow-up duration was approximately ten (range five to 15) years. Patients were evaluated according to the Japan Orthopaedic Association (JOA) hip score. Kaplan-Meier survivorship was calculated to examine revision arthroplasty failure rate. Radiographic analysis of loosening included radiolucent lines and osteolysis of the acetabulum or femur. Causes of loosening were analysed using multiple logistic regression. RESULT: JOA hip score increased from 53 points (preoperative) to 87 points (final follow-up). Survival rates were 96.8 % and 78.6 % at ten and 15 years, respectively. Prosthesis loosening occurred on the acetabular side in five hips (13.5 %). No femoral-component loosening was observed. BHA had poor results in patients with Association Research Circulation Osseous (ARCO) stage IV ONFH and in patients under 40 years of age. CONCLUSION: BHA, with strict surgical indications, may be a good option for treating ONFH. Based on these results, total hip arthroplasty is recommended for patients with ARCO stage IV ONFH or for patients under 40 years of age.

Differential age-related bone architecture changes between female and male STR/Ort mice.

The incidence of spontaneous osteoarthritis (OA) in female STR/Ort mice is much lower than that observed in male STR/Ort mice; however, the reason for the differential incidence of OA between sexes has not been elucidated. Here, we investigated and compared age- and sex-related bone mineral density and architectural changes in male and female STR/Ort mice. Bone architecture and bone mineral density (BMD) of femurs were examined in 5-, 10-, 15-, 20-, and 35-week-old male and female STR/Ort mice by microscopic computed tomography (µCT). Angular degrees of internal tibial torsion (ADITT) were also measured in mice at 5, 15, and 35 weeks of age. Earlier decreases of cancellous volume and BMD were found in male STR/Ort mice. Using µCT, an age-related decline of bone marrow space in femoral diaphysis was observed in both males and females but was more dramatic in females. In addition, an earlier increase of ADITT was observed in male STR/Ort mice, suggesting that internal rotation of the tibia may contribute to OA. Age- and sex-related bone architectural changes clearly differ between male and female STR/Ort mice. These differences in bone structure, particularly ADITT, may explain the differential incidence of OA in STR/Ort mice.

Repeated freeze-thaw cycles reduce the survival rate of osteocytes in bone-tendon constructs without affecting the mechanical properties of tendons.

Frozen bone-patellar tendon bone allografts are useful in anterior cruciate ligament reconstruction as the freezing procedure kills tissue cells, thereby reducing immunogenicity of the grafts. However, a small portion of cells in human femoral heads treated by standard bone-bank freezing procedures survive, thus limiting the effectiveness of allografts. Here, we characterized the survival rates and mechanisms of cells isolated from rat bones and tendons that were subjected to freeze-thaw treatments, and evaluated the influence of these treatments on the mechanical properties of tendons. After a single freeze-thaw cycle, most cells isolated from frozen bone appeared morphologically as osteocytes and expressed both osteoblast- and osteocyte-related genes. Transmission electron microscopic observation of frozen cells using freeze-substitution revealed that a small number of osteocytes maintained large nuclei with intact double membranes, indicating that these osteocytes in bone matrix were resistant to ice crystal formation. We found that tendon cells were completely killed by a single freeze-thaw cycle, whereas bone cells exhibited a relatively high survival rate, although survival was significantly reduced after three freeze-thaw cycles. In patella tendons, the ultimate stress, Young's modulus, and strain at failure showed no significant differences between untreated tendons and those subjected to five freeze-thaw cycles. In conclusion, we identified that cells surviving after freeze-thaw treatment of rat bones were predominantly osteocytes. We propose that repeated freeze-thaw cycles could be applied for processing bone-tendon constructs prior to grafting as the treatment did not affect the mechanical property of tendons and drastically reduced surviving osteocytes, thereby potentially decreasing allograft immunogenecity.

Allogenic serum improves cold preservation of osteochondral allografts.

BACKGROUND: Although several types of culture medium have been used for preservation of osteochondral allografts, the viability of chondrocytes decreases with increasing storage duration. We previously showed the University of Wisconsin solution is more suitable for graft preservation than culture medium. QUESTIONS/PURPOSES: We determined whether the addition of allogenic serum to University of Wisconsin solution increases chondrocyte survival during prolonged storage of osteochondral allografts. METHODS: Osteochondral tissue samples harvested from the distal femora of rats were preserved in University of Wisconsin solution supplemented with 0%, 1%, 10%, and 50% allogenic serum at 4 °C for 14 days. Cell viability and chondrocyte degenerative changes of the samples then were assessed using a tetrazolium assay and histologic methods. We also evaluated time-dependent changes in cell viability and histologic findings of samples preserved for 7, 14, and 21 days in University of Wisconsin solution supplemented with or without 10% allogenic serum. RESULTS: After 14 days of preservation, osteochondral tissue samples maintained in University of Wisconsin solution containing 10% or greater allogenic serum exhibited the highest cell viability and lowest degenerative changes in chondrocytes. In the evaluation of time-dependent changes, we found the chondrocyte degenerative changes were greater in cartilage preserved in University of Wisconsin solution alone than in University of Wisconsin solution containing 10% allogenic serum after day 7 or later. CONCLUSIONS: Our results suggest the addition of 10% allogenic serum to University of Wisconsin solution enhances viability of osteochondral tissue samples. CLINICAL RELEVANCE: The use of allogenic serum-supplemented University of Wisconsin solution is expected to prolong the duration of osteochondral allograft storage and result in higher-quality grafts.

Quality assessment for processed and sterilized bone using Raman spectroscopy.

To eliminate the potential for infection, many tissue banks routinely process and terminally sterilize allografts prior to transplantation. A number of techniques, including the use of scanning electron microscopy, bone graft models, and mechanical property tests, are used to evaluate the properties of allograft bone. However, as these methods are time consuming and often destroy the bone sample, the quality assessment of allograft bones are not routinely performed after processing and sterilization procedures. Raman spectroscopy is a non-destructive, rapid analysis technique that requires only small sample volumes and has recently been used to evaluate the mineral content, mineral crystallinity, acid phosphate and carbonate contents, and collagen maturity in human and animal bones. Here, to establish a quality assessment method of allograft bones using Raman spectroscopy, the effect of several common sterilization and preservation procedures on rat femoral bones were investigated. We found that freeze-thawing had no detectable effects on the composition of bone minerals or matrix, although heat treatment and gamma irradiation resulted in altered Raman spectra. Our findings suggest Raman spectroscopy may facilitate the quality control of allograft bone after processing and sterilization procedures.

Distribution of bone marrow-derived cells in the fracture callus during plate fixation in a green fluorescent protein-chimeric mouse model.

To clarify the distribution of bone-marrow-derived cells in fractures treated by plate fixation, fracture models were created using the green fluorescent protein (GFP) chimeric mouse. We observed 2 types of fracture healing processes with different types of callus formation and cellular events by using Mouse Fix™, a device allowing plate fixation on the mouse femur, and differences in the distribution of bone-marrow-derived cells between the 2 types. The GFP chimeric mice were created by bone marrow transplantation. Fractures were created on the left femurs of mice and stabilized with either rigid (Group R) or flexible (Group F) plates to prepare undecalcified fresh-frozen sections. In Group F, a large external callus and a large intramedullary callus were formed mostly by endochondral ossification. The cells that made up the intramedullary callus and callus in the fracture gap were GFP positive, but most cells of the external callus were not. In Group R, bone union was achieved mostly without external callus formation, bone apposition occurred directly in the gap, and a small intramedullary callus was formed. As observed in Group F, this group had GFP-positive cells in the callus within the fracture gap and in the intramedullary calluses. The results of this study provided direct evidence of the distribution of bone-marrow-derived cells in the callus of fractures treated by plate fixation under different stability conditions.

Hammering sound frequency analysis and prevention of intraoperative periprosthetic fractures during total hip arthroplasty.

Adequate fixation at the time of cementless stem implantation depends on the operator's experience. An objective evaluation method to determine whether the stem has been appropriately implanted may be helpful. We studied the relationship between the hammering sound frequency during stem implantation and internal stress in a femoral model, and evaluated the possible usefulness of hammering sound frequency analysis for preventing intraoperative fracture. Three types of cementless stem (BiCONTACT®, SL-PLUS®, and AI-Hip®) were used. Surgeons performed stem insertion using a procedure similar to that employed in a routine operation. Stress was estimated by finite element analysis, the hammering force was measured, and frequency analysis of hammering sound data obtained using a microphone. Finite element analysis showed a decrease in the hammering sound frequency with an increase in the estimated maximum stress. When a decrease in frequency was observed, adequate hammering had occurred, and the continuation of hammering risked fracture. Based on the relationship between stress and frequency, the evaluation of changes in frequency may be useful for preventing the development of intraoperative fractures. Using our method, when a decrease in frequency is observed, the hammering force should be reduced. Hammering sound frequency analysis may allow the prediction of bone fractures that can be visually confirmed, and may be a useful objective evaluation method for the prevention of intraoperative periprosthetic fractures during stem insertion.

Low intensity pulsed ultrasound accelerates delayed healing process by reducing the time required for the completion of endochondral ossification in the aged mouse femur fracture model.

The aim of this study is to clarify the effect of low intensity pulsed ultrasound (LIPUS) on shortening of the fracture healing period and endochondral ossification during the fracture healing process. We first established a model of aging-related delayed union fractures consisting of aged mouse (C57BL/6J; 40 weeks old) with closed femur fractures. We compared the healing process of 40-week-old mice to the healing process of 8-week-old (young) mice using radiological and histological analysis. In aged mice, some cartilage formation was observed 10 days after the fracture; however, endochondral ossification and hard callus bridging were observed 21 and 28 days after the fracture, respectively, whereas cartilage remained in the callus on day 28, suggesting delayed endochondral ossification following bone remodeling. Meanwhile, in aged mice with LIPUS treatment, cartilage formation was similar to that in aged mice without LIPUS; however, hard callus bridging and bone remodeling were observed 21 and 28 days after fracture, respectively, suggesting that LIPUS shortened the healing period due to promotion of endochondral ossification. Immunohistochemical analysis showed marked expression of vascular endothelial growth factor and neovascularization in the fibrous tissue comprising the periosteum that surrounded the whole callus. A cell migration test involving primary cultured human endothelial cells also showed promotion of cell migration by LIPUS. These results suggested that endothelial cell migration and neovascularization, which were observed around fracture sites, played a part in the mechanism of promotion of endochondral ossification by LIPUS.

Hammering force during cementless total hip arthroplasty and risk of microfracture.

During cementless stem fixation, impaction of the stem is occasionally complicated by bony injuries. Small fractures not visible to the eye during surgery or on post-operative radiographs may remain undetected, and the incidence of such injuries may be underestimated. Employing the same techniques as those employed during total hip arthroplasty, we implanted cementless stems into artificial femora, with equivalent mechanical characteristics to living femora. The hammering force applied to the femur and the displacement of the stem and femur were measured using a load sensor and imaging, respectively. The von Mises stress generated in the femur during cementless stem press-fixation was also measured using finite element analysis. Average hammering force under these conditions (9.25 kN) was sufficient to cause damage to the artificial femur. The first two of eight hammer strikes caused most displacement of the stem. The von Mises stresses generated by the first and second hammer strikes were 31 and 68 MPa, respectively. Applying a high average hammering force to the stem after displacement has ceased probably contributes to the generation of intraoperative fractures during cementless stem fixation. Given that two strikes appeared to be sufficient, we believe that hammering force should be reduced to a micro-adjustment level after the second hit.

Osteoarthritis hip joints in Japan: involvement of acetabular dysplasia.

BACKGROUND: We conducted a nationwide epidemiologic study regarding hip osteoarthritis (OA) in Japan, and a previous report found these patients to be unique in comparison to Caucasians. This report focused on the data regarding each hip joint, and the involvement of acetabular dysplasia with hip OA was analyzed. METHODS: Seven hundred twenty OA hips were examined. Sixty-five joints with osteonecrosis of the femoral head and 215 non-OA contralateral joints of the unilateral patients were examined as controls. The revised system of stage classification for hip OA of the Japanese Orthopedic Association (JOA) was used according to the reproducibility in order to ensure reliable data from the multiple institutions. The acetabular dysplasia indexes were also chosen according to the reproducibility and measured in the radiograph of bilateral hip joints. The clinical score was assessed using the JOA scoring system. The relative risk of the grade of acetabular dysplasia indexes for hip OA was calculated as the odds ratio and the 95% confidence interval. RESULTS: The stage of the OA joints deteriorated with increasing age. The clinical scores also decreased. The grade of the acetabular dysplasia indexes of the OA joints was significantly higher than that of the control joints. Each index of acetabular dysplasia demonstrated significantly increased odds ratios for hip OA. Among the OA joints, the deterioration of the OA stage was found to be significantly associated with an increasing grade of acetabular dysplasia. The odds ratio for OA deterioration in the acetabular dysplasia index was also obtained. The joints of females tended to have a higher grade and prevalence of acetabular dysplasia than those of males. CONCLUSIONS: These findings confirmed a high prevalence of acetabular dysplasia in hip OA joints in Japan. Acetabular dysplasia was one of the most important factors associated with hip OA.