Callus formation is related to the expression ratios of estrogen receptors-alpha and -beta in ovariectomy-induced osteoporotic fracture healing.

INTRODUCTION: This study characterizes ovariectomized (OVX)-induced osteoporotic fracture healing with focus on estrogen receptors (ERs). Callus formation plays a critical role in fracture healing, and ERs are well-known mechanosensors in osteogenic pathways. It was hypothesized that callus formation was related to and partially determined by the difference in expression patterns of ERs in both normal and OVX-induced osteoporotic fractures. METHODS: Closed femoral fracture in SHAM and ovariectomized rats were used in this study. Weekly callus width (CW) and area (CA), endpoint mechanical properties, gene expressions of Col-1, BMP-2, ER-α, ER-ß and ER-α:ER-ß ratios (ER-ratios), and correlations were assessed at 2, 4 and 8 weeks post-fracture. RESULTS: CW and CA results confirmed that OVX-induced osteoporotic fracture was delayed at 2-4 weeks with impaired endpoint mechanical properties. Gene expressions of ER-α and ER-ß were higher in the SHAM group at week 2 (p < 0.05) and later lowered at week 8; whereas the OVX group showed an opposing trend. Moderate correlation existed between ER-α and BMP-2 (0.545, p = 0.003), and ER-ratio and BMP-2 (0.601, p = 0.001), and BMP-2 to CW and CA (r = 0.709, p = 0.000 and r = 0.588, p = 0.001, respectively). ER-α and ER-ß proteins expressions were confirmed by immunohistochemistry at the fracture callus in reparative progenitor cells, osteoblasts- and osteoclasts-like cells. CONCLUSION: We conclude that the delayed healing rate and impaired callus quality in OVX-induced osteoporotic fracture is related to the delayed expression of ERs. A high ER-α:ER-ß ratio favors callus formation.

HR-pQCT for the Evaluation of Muscle Quality and Intramuscular Fat Infiltration in Ageing Skeletal Muscle.

Myosteatosis is the infiltration of fat in skeletal muscle during the onset of sarcopenia. The quantification of intramuscular adipose tissue (IMAT) can be a feasible imaging modality for the clinical assessment of myosteatosis, important for the early identification of sarcopenia patients and timely intervention decisions. There is currently no standardized method or consensus for such an application. The aim of this study was to develop a method for the detection and analysis of IMAT in clinical HR-pQCT images of the distal tibia to evaluate skeletal muscle during the ageing process, validated with animal and clinical experimentation. A pre-clinical model of ovariectomized (OVX) rats with known intramuscular fat infiltration was used, where gastrocnemii were scanned by micro-computed tomography (micro-CT) at an 8.4 µm isotropic voxel size, and the images were analyzed using our modified IMAT analysis protocol. IMAT, muscle density (MD), and muscle volume (MV) were compared with SHAM controls validated with Oil-red-O (ORO) staining. Furthermore, the segmentation and IMAT evaluation method was applied to 30 human subjects at ages from 18 to 81 (mean = 47.3 ± 19.2). Muscle-related parameters were analyzed with functional outcomes. In the animal model, the micro-CT adipose tissue-related parameter of IMAT% segmented at −600 HU to 100 HU was shown to strongly associate with the ORO-positively stained area (r = 0.898, p = 0.002). For the human subjects, at an adjusted threshold of −600 to −20 HU, moderate positive correlations were found between MV and MD (r = 0.642, p < 0.001), and between MV and IMAT volume (r = 0.618, p < 0.01). Moderate negative correlations were detected between MD and IMAT% (r = −0.640, p < 0.001). Strong and moderate associations were found between age and MD (r = −0.763, p < 0.01), and age and IMAT (r = 0.559, p < 0.01). There was also a strong correlation between IMAT% and chair rise time (r = 0.671, p < 0.01). The proposed HR-pQCT evaluation protocol for intramuscular adipose-tissue produced MD and IMAT results that were associated with age and physical performance measures, and were of good predictive value for the progression of myosteatosis or sarcopenia. The protocol was also validated on animal skeletal muscle samples that showed a good representation of histological lipid content with positive correlations, further supporting the clinical application for the rapid evaluation of muscle quality and objective quantification of skeletal muscle at the peripheral for sarcopenia assessment.

An orthogeriatric collaborative intervention program for fragility fractures: a retrospective cohort study.

BACKGROUND: This retrospective cohort study aims to investigate the impact of regular pre- and postoperative geriatric input into the management of geriatric patients with hip fracture, with specific interests in morbidity and mortality. METHODS: Patients with hip fracture (n = 548) older than 60 years were identified within a 2-year period. In the first year, the patients (n = 270) were managed mainly by orthopedics and this group constituted the control group. In the second year, this group of patients (orthogeriatric group, n = 278) had reviews by orthopedic surgeons and geriatricians (physicians specializing in medicine for the elderly), within 48 hours of admission and regularly thereafter. The main outcomes measured included demographics, length of hospital stay, postoperative complications, mortality, and functional outcomes. Data were collected from records of acute and rehabilitation admissions, and outpatient consultations. RESULTS: The admission to operation time for those in the orthogeriatric group was shorter by 17% (p = 0.02). The percentage of patients deceased at 12 months postoperative was 11.5% for the orthogeriatric group and 20.4% for the conventional group (p = 0.02). A higher percentage of patients in the orthogeriatric group remained independent for daily living activities (24.5%) when compared with the conventional group (23.7%; p = 0.02). CONCLUSION: In addition to existing evidence that postoperative orthogeriatric collaboration improves mortality and functional outcomes in older patients with hip fractures, this study suggests that allowing preoperative geriatric input in this model of care can produce even more superior results.

Prognostic factors related to ambulation deterioration after 1-year of geriatric hip fracture in a Chinese population.

The objective of this study was to investigate the prognostic factors predicting the ambulation recovery of fragility hip fracture patients. 2286 fragility hip fracture patients were collected from the Fragility Fracture Registry in Hong Kong. Predictive factors of ambulation deterioration including age, gender, pre-operation American Society of Anesthesiologists grade, pre-fracture mobility, delay to surgery, length of stay, fracture type, type of surgery, discharge destination and complications were identified. Patients with outdoor unassisted and outdoor with aids ambulatory function before fracture had 3- and 1.5-times increased risk of mobility deterioration, respectively (Odds Ratio (OR) = 2.556 and 1.480, 95% Confidence Interval (CI) 2.101-3.111 and 1.246-1.757, both p < 0.001). Patients living in old age homes had almost 1.4 times increased risk of deterioration when compared to those that lived in their homes (OR = 1.363, 95% CI 1.147-1.619, p < 0.001). The risk also increased for every 10 years of age (OR = 1.831, 95% CI 1.607-2.086, p < 0.001). Patients in the higher risk ASA group shows a decreased risk of ambulation deterioration compared to those in lower risk ASA group (OR = 0.831, 95% CI 0.698-0.988, p = 0.038). Patients who suffered from complications after surgery did not increased risk of mobility decline at 1-year post-surgery. Delayed surgery over 48 h, delayed discharge (> 14 days), early discharge (less than 6 days), and length of stay also did not increased risk of mobility decline. Male patients performed worse in terms of their mobility function after surgery compared to female patients (OR = 1.195, 95% CI 1.070-1.335, p = 0.002). This study identified that better premorbid good function, discharge to old age homes especially newly institutionalized patients, increased age, lower ASA score, and male patients, correlate with mobility deterioration at 1-year post-surgery. With the aging population and development of FLS, prompt identification of at-risk patients should be performed for prevention of deterioration.

Fibrinolysis as a target to enhance osteoporotic fracture healing by vibration therapy in a metaphyseal fracture model.

AIMS: Fibrinolysis plays a key transition step from haematoma formation to angiogenesis and fracture healing. Low-magnitude high-frequency vibration (LMHFV) is a non-invasive biophysical modality proven to enhance fibrinolytic factors. This study investigates the effect of LMHFV on fibrinolysis in a clinically relevant animal model to accelerate osteoporotic fracture healing. METHODS: A total of 144 rats were randomized to four groups: sham control; sham and LMHFV; ovariectomized (OVX); and ovariectomized and LMHFV (OVX-VT). Fibrinolytic potential was evaluated by quantifying fibrin, tissue plasminogen activator (tPA), and plasminogen activator inhibitor-1 (PAI-1) along with healing outcomes at three days, one week, two weeks, and six weeks post-fracture. RESULTS: All rats achieved healing, and x-ray relative radiopacity for OVX-VT was significantly higher compared to OVX at week 2. Martius Scarlet Blue (MSB) staining revealed a significant decrease of fibrin content in the callus in OVX-VT compared with OVX on day 3 (p = 0.020). Mean tPA from muscle was significantly higher for OVX-VT compared to OVX (p = 0.020) on day 3. Mechanical testing revealed the mean energy to failure was significantly higher for OVX-VT at 37.6 N mm (SD 8.4) and 71.9 N mm (SD 30.7) compared with OVX at 5.76 N mm (SD 7.1) (p = 0.010) and 17.7 N mm (SD 11.5) (p = 0.030) at week 2 and week 6, respectively. CONCLUSION: Metaphyseal fracture healing is enhanced by LMHFV, and one of the important molecular pathways it acts on is fibrinolysis. LMHFV is a promising intervention for osteoporotic metaphyseal fracture healing. The improved mechanical properties, acceleration of fracture healing, and safety justify its role into translation to future clinical studies. Cite this article: Bone Joint Res 2021;10(1):41-50.

Impact of surgical approach on postoperative heterotopic ossification and avascular necrosis in femoral head fractures: a systematic review.

Heterotopic ossification (HO) and avascular necrosis (AVN) have been identified as post-traumatic complications of femoral head fractures and may lead to a restriction in hip function and permanent disability. The question of which surgical approach is the best for the femoral head fracture and its relationship with HO and AVN remains controversial. We conducted a systematic review in which all published studies were evaluated. We performed a literature search in MEDLINE, PubMed, EMBASE, MD Consult, and the Cochrane Controlled Trial Register from 1980 to April 2009. We found ten appropriate studies, describing 176 patients. A lower percentage of patients treated with a trochanteric flip approach was reported with HO than patients treated with anterior or posterior approach (33.3% versus 42.1% and 36.9%, respectively), although the difference was not statistically significant. The incidence of AVN was highest in the posterior approach group (16.9%), and subsequently with the trochanteric flip approach (12.5%) and the anterior group (7.9%). The investigators concluded that the use of the anterior approach may result in a higher risk for HO and the posterior approach may result in a higher risk for AVN. A new, posterior-based approach of trochanteric flip seems to be a better approach for femoral head fractures. A further case-control study would be appropriate to confirm the findings in our systematic review.

Vibration and ß-hydroxy-ß-methylbutyrate treatment suppresses intramuscular fat infiltration and adipogenic differentiation in sarcopenic mice.

BACKGROUND: Sarcopenia is an aging-induced deterioration of skeletal muscle mass and function. Low-magnitude high-frequency vibration (LMHFV) was shown to improve muscle functions and ß-hydroxy-ß-methylbutyrate (HMB) to increase muscle mass and strength. Muscle-derived stem cells (MDSCs) are progenitor cells important for muscle regeneration. We hypothesized that LMHFV and HMB could retard sarcopenia by reducing fat infiltration through inhibiting adipogenesis in MDSCs. METHODS: Senescence-accelerated mouse P8 male mice were randomized into control (CTL), HMB, LMHFV (VIB), and combined (COM) groups. Interventions started at age of month 7 and assessed at 1, 2, and 3 months post-intervention by densitometry, histology, and functional tests. In vitro, MDSCs isolated from gastrocnemius of senescence-accelerated mouse P8 mice were characterized, randomized into CTL, VIB, HMB, and COM groups, and assessed by oil red O staining, mRNA, and protein expression. RESULTS: At 2 months post-intervention, percentage lean mass of HMB, VIB, and COM groups were significantly higher than CTL group. Twitch, tetanic, and specific tetanic forces of COM group were higher, while specific twitch force of both VIB and COM groups were higher. Grip strength of HMB, VIB, and COM groups were higher. Histologically, both VIB and COM groups presented lower oil red O area than CTL group. Type I muscle fibre in CTL group was higher than HMB, VIB, and COM groups. MDSC were detected in situ by immunofluorescence stain with stem cell antigen-1 signals confirmed with higher ß-catenin expression in the COM group. The observations were also confirmed in vitro, MDSCs in the HMB, VIB, and COM groups presented lower adipogenesis vs. the CTL group. ß-Catenin mRNA and protein expressions were lower in the CTL group while their relationship was further validated through ß-catenin knock-down approach. CONCLUSIONS: Our results showed that combined LMHFV and HMB interventions enhanced muscle strength and decreased percentage fat mass and intramuscular fat infiltration as compared with either treatment alone. Additive effect of LMHFV and HMB was demonstrated in ß-catenin expression than either treatment in MDSCs and altered cell fate from adipogenesis to myogenesis, leading to inhibition of intramuscular lipid accumulation. Wnt/ß-catenin signalling pathway was found to be the predominant regulatory mechanism through which LMHFV and HMB combined treatment suppressed MDSCs adipogenesis.

Articular cartilage increases transition zone regeneration in bone-tendon junction healing.

The fibrocartilage transition zone in the direct bone-tendon junction reduces stress concentration and protects the junction from failure. Unfortunately, bone-tendon junctions often heal without fibrocartilage transition zone regeneration. We hypothesized articular cartilage grafts could increase fibrocartilage transition zone regeneration. Using a goat partial patellectomy repair model, autologous articular cartilage was harvested from the excised distal third patella and interposed between the residual proximal two-thirds bone fragment and tendon during repair in 36 knees. We evaluated fibrocartilage transition zone regeneration, bone formation, and mechanical strength after repair at 6, 12, and 24 weeks and compared them with direct repair. Autologous articular cartilage interposition resulted in more fibrocartilage transition zone regeneration (69.10% +/- 14.11% [mean +/- standard deviation] versus 8.67% +/- 7.01% at 24 weeks) than direct repair at all times. There was no difference in the amount of bone formation and mechanical strength achieved. Autologous articular cartilage interposition increases fibrocartilage transition zone regeneration in bone-tendon junction healing, but additional research is required to ascertain the mechanism of stimulation and to establish the clinical applicability.

The efficacy of a multidisciplinary falls prevention clinic with an extended step-down community program.

OBJECTIVE: To investigate the efficacy of a falls prevention clinic and a community step-down program in reducing the number of falls among community-dwelling elderly at high risk of fall. DESIGN: Prospective cohort. SETTING: Community. PARTICIPANTS: Community-dwelling elderly (N=200) were screened for risk of fall; 60 were identified as being at high risk and were referred to the intervention program. INTERVENTION: Twelve sessions of a once-a-week falls prevention clinic, including fall evaluation, balance training, home hazard management program, and medical referrals, were provided in the first 3 months. The community step-down program, including falls prevention education, a weekly exercise class, and 2 home visitations, was provided in the following 9 months. MAIN OUTCOME MEASURES: Fall rate, injurious fall, and its associated medical consultation were recorded during the intervention period and the year before intervention. Balance tests included the Berg Balance Scale (BBS), Sensory Organization Test, and limits of stability test; fear of falling, as evaluated using the Activities-specific Balance Confidence (ABC) scale, was measured at baseline and after the training in the falls prevention clinic. RESULTS: Significant reductions in fall rate (74%), injurious falls (43%), and fall-associated medical consultation (47%) were noted. Significant improvement in balance scores (BBS, P<.001; endpoint excursion in limits of stability test, P=.004) and fear of falling (ABC scale, P=.001) was shown. CONCLUSIONS: The programs in the falls prevention clinic were effective in reducing the number of falls and injurious falls. The community step-down programs were crucial in maintaining the intervention effects of the falls prevention clinic.

Evaluation of a multidisciplinary rehabilitation programme for elderly patients with hip fracture: A prospective cohort study.

OBJECTIVE: To investigate the effectiveness and cost of an 18-month multi-disciplinary Comprehensive Fragility Fracture Management Program (CFFMP) for fragility hip fracture patients. DESIGN: Prospective cohort study. PATIENTS: Elderly patients with hip fracture were recruited at their first postoperative follow-up in 2 district hospitals. The intervention group comprised patients from the hospital undergoing CFFMP, and the control group comprised patients from another hospital undergoing conventional care. CFFMP provided geri-orthopaedic co-management, physician consultations, group-exercise and vibration-therapy. Timed-up-and-go test (TUG), Elderly Mobility Scale (EMS), Berg Balance Scale (BBS) and fall risk screening (FS) were used to assess functional performance. Incidences of falls and secondary fractures, the cost of the programme and related healthcare resources were recorded. RESULTS: A total of 76 patients were included in the intervention group (mean age 77.9 years ((standard deviation; SD) 6.1) ) and 77 in the control group (79.9 (SD 7.2)), respectively. The re-fracture rate in the control group (10.39%) was significantly higher than in the intervention group (1.32%) (p = 0.034). The intervention group improved significantly in TUG, EMS and FS after a 1-year programme. The overall healthcare costs per patient in the intervention and control groups were US$22,450 and US$25,313, respectively. CONCLUSION: Multi-disciplinary CFFMP is effective, with reduced overall cost, reduced length of hospital stay and reduced secondary fracture rate. The rehabilitation community service favours rehabilitation and improved quality of life of hip fracture patients.

One-year mortality in displaced intracapsular hip fractures and associated risk: a report of Chinese-based fragility fracture registry.

BACKGROUND: The purpose of this registry-based retrospective study was to investigate the risk factors related to one-year mortality in displaced intracapsular fragility hip fracture patients. METHODS: Patients were screened from the Fragility Fracture Registry. Inclusion criterion was displaced intracapsular hip fracture patients with atypical or pathological fractures excluded. One-year mortality was investigated against risk factors including age, gender, past medical history, pre-fracture mobility (PFM), pre-operation ASA grade, delayed surgery over 48 h, post-surgical complications, and length of stay at acute orthopedic ward (LOS). RESULTS: A total of 1050 patients were included for further analysis. Gross one-year mortality was 14.9%. One-year mortality was significantly higher in patients who received non-operative treatment and those who received surgery but delayed over 48 h after admission (both p <  0.001). Male gender (OR = 2.708), advanced age (OR = 1.359), higher risk ASA grades (III to V) (OR = 1.990), past history of gastrointestinal disease (OR = 1.671), and renal impairment (OR = 1.984) were related to higher one-year mortality. The mortality of patients in PFM grade 3 and LOS group 3 was significantly higher (OR = 2.240 and 1.722, respectively). CONCLUSIONS: Higher age, male gender, past gastrointestinal disease and renal impairment, ASA grade over 3, indoor confined pre-fracture ambulatory, and stay at hospital over 15 days were risk factors related to higher one-year mortality in surgically treated displaced intracapsular hip fracture patients. A multi-disciplinary approach is advised to patients identified with these risks factors and co-managed by orthopedic surgeons, geriatricians, and fracture liaison nurses.

Inflammation and age-associated skeletal muscle deterioration (sarcopaenia).

Ageing is accompanied by chronic inflammatory responses due to elevated circulatory inflammatory cytokine production. Several inflammatory cytokines have been shown to be responsible for a decrease in muscle mass. However, little is known about the possible relationship between inflammation and sarcopaenia. This review aims to summarise the existing evidence about inflammation and sarcopaenia. Sarcopaenia is defined as an age-related decrease of muscle mass and/or muscle strength; it is caused by multiple factors, such as skeletal muscle atrophy, neuromuscular junction degeneration, hormone imbalance, cytokine imbalance, protein synthesis and proteolysis. Several inflammatory cytokines have been considered to promote muscle loss; C-reactive protein levels are significantly upregulated in sarcopaenia and sarcopenic obesity, and high levels of interleukin-6 are associated with reduced muscle mass and muscle strength (the administration of interleukin-6 could lead to a reduction in muscle mass). Up-regulation of tumour necrosis factor-α expression is also related to the development of sarcopaenia. Signalling pathways, such as protein kinase B/mammalian target of rapamycin, Janus kinase/signal transducer and activator of transcription-5 and signal transducer and activator of transcription 3 signalling, involved in muscle metabolism are regulated by insulin-like growth factor-1, tumour necrosis factor-α and interleukin-6 respectively. In conclusion, the inflammatory cytokines produced during chronic inflammation due to ageing, may influence their respective related pathways, thus leading to age-related muscle deterioration. THE TRANSLATIONAL POTENTIAL OF THIS ARTICLE: This review can provide more information for sarcopaenia medicine research in terms of anti-inflammation therapy.

Ultrasound as a stimulus for musculoskeletal disorders.

Ultrasound is an inaudible form of acoustic sound wave at 20 kHz or above that is widely used in the medical field with applications including medical imaging and therapeutic stimulation. In therapeutic ultrasound, low-intensity pulsed ultrasound (LIPUS) is the most widely used and studied form that generally uses acoustic waves at an intensity of 30 mW/cm2, with 200 ms pulses and 1.5 MHz. In orthopaedic applications, it is used as a biophysical stimulus for musculoskeletal tissue repair to enhance tissue regeneration. LIPUS has been shown to enhance fracture healing by shortening the time to heal and reestablishment of mechanical properties through enhancing different phases of the healing process, including the inflammatory phase, callus formation, and callus remodelling phase. Reports from in vitro studies reveal insights in the mechanism through which acoustic stimulations activate cell surface integrins that, in turn, activate various mechanical transduction pathways including FAK (focal adhesion kinase), ERK (extracellular signal-regulated kinase), PI3K, and Akt. It is then followed by the production of cyclooxygenase 2 and prostaglandin E2 to stimulate further downstream angiogenic, osteogenic, and chondrogenic cytokines, explaining the different enhancements observed in animal and clinical studies. Furthermore, LIPUS has also been shown to have remarkable effects on mesenchymal stem cells (MSCs) in musculoskeletal injuries and tissue regeneration. The recruitment of MSCs to injury sites by LIPUS requires the SDF-1 (stromal cell derived factor-1)/CXCR-4 signalling axis. MSCs would then differentiate differently, and this is regulated by the presence of different cytokines, which determines their fates. Other musculoskeletal applications including bone-tendon junction healing, and distraction osteogenesis are also explored, and the results are promising. However, the use of LIPUS is controversial in treating osteoporosis, with negative findings in clinical settings, which may be attributable to the absence of an injury entry point for the acoustic signal to propagate, strong attenuation effect of cortical bone and the insufficient intensity for penetration, whereas in some animal studies it has proven effective.

An animal model of co-existing sarcopenia and osteoporotic fracture in senescence accelerated mouse prone 8 (SAMP8).

Sarcopenia and osteoporotic fracture are common aging-related musculoskeletal problems. Recent evidences report that osteoporotic fracture patients showed high prevalence of sarcopenia; however, current clinical practice basically does not consider sarcopenia in the treatment or rehabilitation of osteoporotic fracture. There is almost no report studying the relationship of the co-existing of sarcopenia and osteoporotic fracture healing. In this study, we validated aged senescence accelerated mouse prone 8 (SAMP8) and senescence accelerated mouse resistant 1 (SAMR1) as animal models of senile osteoporosis with/without sarcopenia. Bone mineral density (BMD) at the 5th lumbar and muscle testing of the two animal strains were measured to confirm the status of osteoporosis and sarcopenia, respectively. Closed fracture was created on the right femur of 8-month-old animals. Radiographs were taken weekly post-fracture. MicroCT and histology of the fractured femur were performed at week 2, 4 and 6 post-fracture, while mechanical test of both femora at week 4 and 6 post-fracture. Results showed that the callus of SAMR1 was significantly larger at week 2 but smaller at week 6 post-fracture than SAMP8. Mechanical properties were significantly better at week 4 post-fracture in SAMR1 than SAMP8, indicating osteoporotic fracture healing was delayed in sarcopenic SAMP8. This study validated an animal model of co-existing sarcopenia and osteoporotic fracture, where a delayed fracture healing might be resulted in the presence of sarcopenia.

Low-Magnitude High-Frequency Vibration Accelerated the Foot Wound Healing of n5-streptozotocin-induced Diabetic Rats by Enhancing Glucose Transporter 4 and Blood Microcirculation.

Delayed wound healing is a Type 2 diabetes mellitus (DM) complication caused by hyperglycemia, systemic inflammation, and decreased blood microcirculation. Skeletal muscles are also affected by hyperglycemia, resulting in reduced blood flow and glucose uptake. Low Magnitude High Frequency Vibration (LMHFV) has been proven to be beneficial to muscle contractility and blood microcirculation. We hypothesized that LMHFV could accelerate the wound healing of n5-streptozotocin (n5-STZ)-induced DM rats by enhancing muscle activity and blood microcirculation. This study investigated the effects of LMHFV in an open foot wound created on the footpad of n5-STZ-induced DM rats (DM_V), compared with no-treatment DM (DM), non-DM vibration (Ctrl_V) and non-DM control rats (Ctrl) on Days 1, 4, 8 and 13. Results showed that the foot wounds of DM_V and Ctrl_V rats were significantly reduced in size compared to DM and Ctrl rats, respectively, at Day 13. The blood glucose level of DM_V rats was significantly reduced, while the glucose transporter 4 (GLUT4) expression and blood microcirculation of DM_V rats were significantly enhanced in comparison to those of DM rats. In conclusion, LMHFV can accelerate the foot wound healing process of n5-STZ rats.

The characterization of a full-thickness excision open foot wound model in n5-streptozotocin (STZ)-induced type 2 diabetic rats that mimics diabetic foot ulcer in terms of reduced blood circulation, higher C-reactive protein, elevated inflammation, and reduced cell proliferation.

Delayed foot wound healing is a major complication attributed to hyperglycemia in type 2 diabetes mellitus (DM) patients, and these wounds may develop into foot ulcers. There are at least two types of DM wound models used in rodents to study delayed wound healing. However, clinically relevant animal models are not common. Most models use type 1 DM rodents or wounds created on the back rather than on the foot. An open full-thickness excision wound on the footpad of type 2 DM rats is more clinically relevant, but such a model has not yet been characterized systematically. The objective of this study was to investigate and characterize how DM affected a full-thickness excision open foot wound in n5-streptozotocin (n5-STZ)-induced type 2 DM rats. We hypothesized that elevated inflammation, reduced blood circulation, and cell proliferation due to hyperglycemia could delay the wound healing of DM rats. The wounds of DM rats were compared with those of non-DM rats (Ctrl) at Days 1 and 8 post wounding. The wound healing process of the DM rats was significantly delayed compared with that of the Ctrl rats. The DM rats also had higher C-reactive protein (CRP) and lower blood circulation and proliferating cell nuclear antigen (PCNA) in DM wounds. This confirmed that elevated inflammation and reduced blood flow and cell proliferation delayed foot wound healing in the n5-STZ rats. Hence, this open foot wound animal model provides a good approach to study the process of delayed wound healing.

Low intensity pulsed ultrasound accelerated bone remodeling during consolidation stage of distraction osteogenesis.

Bone regeneration in distraction osteogenesis occurs under tensile stress with axial rhythmic distraction after osteotomy. In this study, we evaluated if the low intensity pulsed ultrasound (LIPUS) was also effective on enhancement of bone remodeling during consolidation stage of distraction osteogenesis. Open osteotomy of seventeen 18-week-old female New Zealand rabbit tibiae were performed. The distraction was applied with the rate of 1 mm per day. LIPUS (30 mW/cm(2), 1.5 MHz) was delivered for 20 min per day during 4-week consolidation stage (n=10). The animals without treatment served as sham group (n=7). Plain X-ray, peripheral quantitative computational tomography (pQCT), and torsional test were performed. Results showed that smaller radiolucent interzone of LIPUS treatment group was gradually occupied by calcified tissue in plain X-ray at week 2. The bone mineral density (BMD) measured on radiographs increased by 9.18% in the LIPUS group. Bone mineral content (BMC), hard callus volume, and bone strength index (BSI) measured by pQCT were 83%, 116%, and 94%, respectively, in LIPUS group that were significantly greater than those of the controls. At the 4th week, LIPUS-treated callus showed the development of neocorticalization in the proximal and distal region. The BMC, hard callus volume, and BSI of LIPUS group decreased and was not significantly different from control. This was also confirmed by the maximum torque of LIPUS-treated callus (1424.2+/-457.3 N . mm) obtained at week 4, which did not differ from that of the sham group (1968.8+/-895.1 N . mm). In conclusion, the effective period of LIPUS treatment was at the initial stage of consolidation, with accelerated bone formation and remodeling.

Dose-dependent effect of low-intensity pulsed ultrasound on callus formation during rapid distraction osteogenesis.

Distraction osteogenesis of bone or callotasis causes poor bone formation when the distraction rate is beyond the optimal rate. Low-intensity pulsed ultrasound was reported to enhance fracture healing, treatment of nonunion, and accelerate bone maturation and remodeling during consolidation stage of distraction osteogenesis. In this study, we evaluated the efficacy of different durations of LIPUS treatments during rapid bone lengthening. After 7-day latent period, osteotomized New Zealand white rabbit tibiae were lengthened at the rate of 2 mm per day for 1 week. Two different LIPUS treatment durations of 20 min and 40 min were selected for treatment groups. Rabbits without treatment served as the control group. Plain X-ray, peripheral quantitative computed tomography (pQCT) and histology were performed to assess bone acquisition in the distraction callus. The results showed that LIPUS increased bone mineral content and volume of the mineralized tissue of distraction callus in a dose-dependent manner. The different regions of distraction callus exhibited various spatial response to LIPUS treatment. Moreover, LIPUS enhanced dose-dependant endochondral formation. Compared with 20-min treatment, the 40-min LIPUS treatment was a more favorable treatment duration for bone regeneration in the distraction callus. In conclusion, LIPUS was able to enhance bone regeneration under rapid distraction, and its effect was dose-dependent.

An in vitro optimized injectable calcium phosphate cement for augmenting screw fixation in osteopenic goats.

This study reports the proportioning and standardized mixing procedures for preparing a hydroxylapatite cement (tetracalcium phosphate and dicalcium phosphate) of desired viscosity and mechanical strength reproducibly for application in trauma surgery. The behavior and the biomechanical properties of the resulting bone cement in screw augmentation were then evaluated in our osteopenic goat model. The use of a shaker standardized the mixing procedure. The optimal volume of Na2HPO4 used to prepare the injectable cement was 0.45 mL/g, with averaged in vitro compressive strength of 48.29 +/- 5.62 MPa. Histology showed increasing tightly-coupled bone apposition on the cement surface without fibrous encapsulation as observed in the screw-only controls with time in the osteopenic goat model. The cement increased the initial screw pull-out force (54.7%, p = 0.005) significantly and the energy required to failure (54.7%, p < 0.05) significantly, and remained higher than the screw-only controls after 3 months (9.8% and 20.2%, respectively) and 6 months (20.2% and 44.7%, respectively). These results imply potential in the prevention of interfacial micromotions and subsequent fibrous tissue formation at the implant-bone interface resulting in a decreased risk of implant failure. The optimized cement in this study may serve as a good candidate for augmenting fixation of osteoporotic bone.

Ultrasound and fragility fracture: is there a role?

Osteoporotic fracture is known to have impaired healing capacity and therefore takes longer time to heal, as compared with younger one. The mechanism of impaired osteoporotic fracture healing is multifactorial, where lower responsiveness to mechanical loading is generally believed to be one factor, yet not absolutely confirmed. In recent years, low intensity pulsed ultrasound (LIPUS) is demonstrated to have good efficacy in treating normal fracture healing, as proven by many randomized controlled trials, as well as in vitro and animal evidences. The effects of LIPUS on osteoporotic fracture healing was also validated in an animal study, which revealed that osteoporotic fractured bone of SD rats showed radiologically and biomechanically comparable responses to LIPUS as age-matched normal fracture healing, in terms of callus width, bridging rate, bone volume fraction, and stiffness etc. Gene expression profiling also confirmed that osteoporotic fractured bone responded to LIPUS very well by upregulating Col1 and BMP2 (osteogenesis) at early phase, VEGF (angiogenesis) at middle phase and RANKL (remodeling) at late phase. These confirm that osteoporotic bones respond well to LIPUS as good as normal bone. These findings may be associated with estrogen receptors (ERs), as estrogen depletion is sensed and relayed by ERs and ERs also function as mechano-sensors. A previous study observed a delayed ERs expression pattern in fracture callus of OVX rats, as compared with SHAM rats, which correlated well with the expression pattern of BMP-2 (callus formation-related gene). Hence, the responses of osteoporotic fractured bone to LIPUS may be related to the local ERs expression at fracture callus that needs further experiments to validate.