Radius Shaft Research Articles

Atypical insertion of the abductor pollicis longus muscle, an anatomical case report

During a routine dissection of upper limb in the Department of Anatomy, we came across an unusual attachment of the abductor pollicis longus muscle. Proximal fleshy belly of it originated from the dorsal surface of the shaft of the radius as usual. As it descended it split into two tendons (lateral and medial) proximal to the wrist. The medial tendon attached to the lateral side of base of the first metacarpal bone, whereas the lateral tendon again converted into a fleshy belly at its distal part and inserted into the proximal phalanx of the thumb overlapping the insertion of the abductor pollicis brevis. Double tendons of abductor pollicis longus, each inserting separately into different sites is a rare incidence and needs to be reported to enhance the success rate of any surgical procedures at this region.

Bone Structure and Geometric Properties at the Radius and Tibia in Adolescent Endurance-Trained Cyclists.

To describe cortical and trabecular volumetric bone mineral density (vBMD), bone mineral content (BMC), cross-sectional area (CSA), and bone strength indexes (BSIs) in adolescent endurance-trained cyclists (CYC) and compare them with controls (CON). Descriptive cohort study. Twenty-five male adolescent CYC and 17 CON. Peripheral quantitative computed tomography was used to evaluate proximal and distal sites of the radius and tibia. Total, trabecular, and cortical BMC, vBMD, and CSA were measured. Also, cortical thickness, endosteal and periosteal circumferences, and different BSIs were calculated. Unadjusted analysis of variance and body weight-adjusted analysis of covariance tests were applied between cyclist and control groups. Cyclists were almost 12% lighter than CON (P < 0.05). Unadjusted data showed lower distal total vBMD and proximal cortical BMC and vBMD in cyclists compared with CON at the radius (P < 0.05) and lower distal total and trabecular BMC, vBMD and bone area, proximal total and cortical BMC and vBMD, and cortical bone area at the tibia (P < 0.05). Body weight-adjusted data showed the same differences for distal total vBMD at the radius and total and trabecular BMC and vBMD at the tibia, diaphyseal radius cortical vBMD and tibia total vBMD, cortical BMC and area, and also for tibia cortical thickness and BSI. The rest of differences were no longer detectable and bone area at the distal radius become significantly higher in cyclist compared with CON (P < 0.05). Adolescent CYC in this study showed lower values of BMC and vBMD at determined sites of the radius and tibia than CON, some of these differences were explained in part by their lower body weight. However, even further adjustment, some differences remained, which indicates that further longitudinal studies are needed to better understand if cycling influences these differences.

Are milk and alternatives and fruit and vegetable intakes during adolescence associated with cortical and trabecular bone structure, density, and strength in adulthood?

The purpose of this study was to investigate whether adolescents with high intake of milk and alternatives (M&A) or fruit and vegetables (F&V) had better adult bone structure and strength compared to those with low intake levels. We analyzed data from 47 males and 69 females enrolled in the Pediatric Bone Mineral Accrual Study (PBMAS 1991-2011), who had one peripheral quantitative computed tomography scan at age 29 ± 2years. We measured radius and tibia shaft total area (ToA), cortical area (CoA), cortical content (CoC), cortical density, bone strength (SSIp), and muscle area, as well as distal radius and tibia ToA, total density, trabecular area, trabecular content, trabecular density, and bone strength (BSIc). Sequential 24-h recalls were used to assess M&A and F&V intake; participants were grouped for their mean intake during adolescence (low = bottom quartile, moderate = middle quartiles, high = top quartile) and were compared using multivariate analysis of covariance while adjusting for adult height, muscle area, physical activity, energy and calcium intake and adolescent energy intake, and physical activity. Females with high M&A intake compared to low M&A intake group (mean 3.8 vs. 1.3 servings/day, respectively) had greater adult ToA (14%, p < 0.05), CoA (15%, p < 0.01), and CoC (16%, p < 0.01) at radius shaft. Females with moderate F&V intake compared to low F&V intake group (mean 3.7 vs. 2.1 servings/day, respectively) had greater adult ToA (8.5%, p < 0.05) at distal tibia. Higher intake of M&A or F&V during adolescence had a long-term beneficial effect on bone structure in females, an association not observed in males.

Minimally Invasive Plate Osteosynthesis of Comminuted One Bone Fractures of Forearm Shaft

Objective: Due to rotatability of the forearm, open reduction and internal fixation with plate is a gold standard treatment of forearm fracture. Our hypothesis was that if it does not make any problems on alignment and rotation, minimally invasive plate osteosynthesis (MIPO) technique could be also applied for forearm fracture. It is easy to align when only one of forearm bone is fractured because reference point exists. The purpose of this study is to introduce MIPO technique for comminuted one bone fracture of forearm shaft. Methods: Between May 2011 and January 2014, 17 patients with fractures of forearm shaft were treated by MIPO technique. MIPO technique was applied to single forearm bone shaft fractures or to the more severe comminuted bone when both forearm bones are fractured. The other less sever bone fracture is treated with open reduction and internal fixation. There were 5 cases of forearm both bone fracture (radius 3, ulna 2), 5 cases of radius shaft fracture, and 7 cases of ulnar shaft fracture. MIPO technique was applied in total 8 cases of radius fracture and 9 cases of ulna fracture. The mean follow-up period was 26 months (range, 24-44 months). Bone union period was determined by radiographs taken upon follow up, and clinical function was evaluated by range of movement, Grace and Eversmann criteria measured at the last follow up. Results: Bony union was achieved in all patients. The mean time to bone union was 10.8 weeks in radius and 13.4 weeks in ulna. The average range of motion of forearm was 80.6° in supination and 83.2° in pronation. Both groups showed mean percentage of 97 compared with the contralateral side. Functional results assessed by Grace and Eversmann criteria were rated excellent in 11 cases and good in 6 cases. Conclusion: In our series, MIPO technique for comminuted one bone fractures in forearm shaft fracture was safe and effective, which had advantages, including a small skin incision, in bone biology.

Bone Traits Seem to Develop Also During the Third Decade in Life—Normative Cross-Sectional Data on 1083 Men Aged 18–28 Years

By identifying individuals with low peak bone mass (PBM) at young age, early targeted interventions to reduce future fracture risk could be possible. Peripheral quantitative computed tomography (pQCT) is in many ways superior to the gold standard dual-energy X-ray absorptiometry (DXA), as cortical and trabecular compartments as well as the volumetric density and bone structure can be examined separately. Because each of these traits contributes independently to bone strength, it is probable that pQCT provides an even better fracture risk estimation than DXA. Currently, the clinical applications of pQCT are limited partly because comprehensive normative pQCT data, especially in young men, are not readily available. We therefore set up a study in young men with the following objectives: (1) to identify peak ages in pQCT bone traits with special reference to PBM and peak bone strength; and (2) to provide normative pQCT data. We measured volumetric bone mineral density and structural parameters at ultradistal (trabecular bone) and diaphyseal radius and tibia (cortical bone) by pQCT scans (Stratec XCT2000®; Stratec Medizintechnik GmbH, Pforzheim, Germany) in a population-based age-stratified sample of 1083 men aged 18–28 yr residing in greater Malmö, Sweden. Group differences in 1-yr classes were evaluated by analysis of variance. We found similar bone traits in age groups at ultradistal sites whereas most bone traits at diaphyseal sites were higher with higher ages, however with different increment patterns depending on the specific trait. In Swedish young adult men, we found that different bone traits continued to change after age 18, but at different rates, indicating that peak areal bone mineral density (as measured by DXA) and peak bone strength may be reached at different ages.

Menopause, Reproductive Life, Hormone Replacement Therapy, and Bone Phenotype at Age 60-64 Years: A British Birth Cohort.

Context:Previous studies of menopausal age and length of reproductive life on bone are limited by retrospective reproductive histories, being cross-sectional, or lacking gold standard bone technologies or information on hormone replacement therapy (HRT) or surgical treatment.Objective:The objective of the study was to investigate age at menopause, length of reproductive life, and HRT use in relation to volumetric and areal bone mineral density (vBMD, aBMD), bone size, and strength in women aged 60–64 years.Design:This was a birth cohort study that followed up for 64 years with prospective measures of age at menarche and menopause and monthly HRT histories.Setting:The study was conducted in England, Scotland, and Wales.Participants:Participants included 848 women with a known type of menopause and bone measures at 60–64 years.Main Outcome Measures:Peripheral quantitative computed tomography measurements of the distal radius total and trabecular vBMD were measured. Diaphyseal radius total and medullary cross-sectional area, cortical vBMD, and polar strength strain index (SSI); dual-energy x-ray absorptiometry measurements of aBMD at the lumbar spine and total hip were also measured.Results:A 10-year increase in age at natural (but not surgical) menopause was associated with 8.2% (95% confidence interval [CI] 1.3%–15.1%, P = .02) greater trabecular vBMD and a 6.0% (95% CI 0.51%–11.5%, P = .03) greater total vBMD; findings were similar for length of reproductive life. A 10-year difference in HRT use was associated with a 6.0% (95% CI 2.6%–9.3%, P < .001) greater polar SSI and a 0.9% (95% CI 0.4%–1.5%, P = .001) greater cortical vBMD. These estimates changed little on adjustment. Estimates for aBMD were consistent with those for peripheral quantitative computed tomography.Conclusions:The positive effects on trabecular vBMD of later natural menopause and longer reproductive life persisted into early old age. HRT use was associated with greater radius cortical vBMD and polar SSI and aBMD.

Ethnic differences in bone geometry between White, Black and South Asian men in the UK

Relatively little is known about the bone health of ethnic groups within the UK and data are largely restricted to women. The aim of this study was to investigate ethnic differences in areal bone mineral density (aBMD), volumetric bone mineral density (vBMD), bone geometry and strength in UK men.White European, Black Afro-Caribbean and South Asian men aged over 40years were recruited from Greater Manchester, UK. aBMD at the spine, hip, femoral neck and whole body were measured by DXA. Bone geometry, strength and vBMD were measured at the radius and tibia using pQCT at the metaphysis (4%) and diaphysis (50% radius; 38% tibia) sites. Adjustments were made for age, weight and height.Black men had higher aBMD at the whole body, total hip and femoral neck compared to White and South Asian men independent of body size adjustments, with no differences between the latter two groups. White men had longer hip axis lengths than both Black and South Asian men. There were fewer differences in vBMD but White men had significantly lower cortical vBMD at the tibial diaphysis than Black and South Asian men (p<0.001). At the tibia and radius diaphysis, Black men had larger bones with thicker cortices and greater bending strength than the other groups. There were fewer differences between White and South Asian men. At the metaphysis, South Asian men had smaller bones (p=0.02) and lower trabecular vBMD at the tibia (p=0.003). At the diaphysis, after size-correction, South Asian men had similar sized bones but thinner cortices than White men; measures of strength were not broadly reduced in the South Asian men.Combining pQCT and DXA measurements has given insight into differences in bone phenotype in men from different ethnic backgrounds. Understanding such differences is important in understanding the aetiology of male osteoporosis.

7T MRI of distal radius trabecular bone microarchitecture: How trabecular bone quality varies depending on distance from end-of-bone.

To use 7T magnetic resonance imaging (MRI) to determine how trabecular bone microarchitecture varies at the epiphysis, metaphysis, and diaphysis of the distal radius. The distal radius of 24 females (mean age = 56 years, range = 24-78 years) was scanned on a 7T MRI using a 3D fast low-angle shot sequence (0.169 × 0.169 × 1 mm). Digital topological analysis was applied at the epiphysis, metaphysis, and diaphysis to compute: total trabecular bone volume; trabecular thickness, number, connectivity, and erosion index (a measure of network resorption). Differences and correlations were assessed using standard statistical methods. The metaphysis and epiphysis had 83-123% greater total bone volume and 14-16% greater trabecular number than the diaphysis (both P < 0.0001). The erosion index was significantly higher at the diaphysis than the metaphysis and epiphysis (both P < 0.01). The most elderly volunteers had lower trabecular number (<66 years mean 0.29 ± 0.01; ≥66 years, 0.27 ± 0.02, P < 0.05) and higher erosion index (<66 years mean 1.18 ± 0.17; age ≥66 years, mean 1.42 ± 0.46, P < 0.05) at the epiphysis; differences not detected by total trabecular bone volume. 7T MRI reveals trabecular bone microarchitecture varies depending on scan location at the end-of-bone, being of overall higher quality distally (epiphysis) than proximally (diaphysis). Age-related differences in trabecular microarchitecture can be detected by 7T MRI. The results highlight the potential sensitivity of 7T MRI to microarchitectural differences and the potential importance of standardizing scan location for future clinical studies of fracture risk or treatment response. 3 J. Magn. Reson. Imaging 2017;45:872-878.

Increased bone formation in a rabbit long-bone defect model after single local and single systemic application of erythropoietin

Background and purpose — Delayed bone healing with non-union is a common problem. Further options to increase bone healing together with surgery are needed. We therefore evaluated a 1-dose single application of erythropoietin (EPO), applied either locally to the defect or systemically during surgery, in a critical-size rabbit long-bone defect.Material and methods — 19 New Zealand White rabbits received a 15-mm defect in the radius diaphysis. An absorbable gelatin sponge was soaked with saline (control group and systemic treatment group) or EPO (local treatment group) and implanted into the gap. The systemic treatment group received EPO subcutaneously. In vivo micro-CT analysis was performed 4, 8, and 12 weeks postoperatively. Vascularization was evaluated histologically.Results — Semiquantitative histomorphometric and radiological evaluation showed increased bone formation (2.3- to 2.5-fold) in both treatment groups after 12 weeks compared to the controls. Quantitative determination of bone volume and tissue volume showed superior bone healing after EPO treatment at all follow-up time points, with the highest values after 12 weeks in locally treated animals (3.0- to 3.4-fold). More vascularization was found in both EPO treatment groups.Interpretation — Initial single dosing with EPO was sufficient to increase bone healing substantially after 12 weeks of follow-up. Local application inside the defect was most effective, and it can be administered directly during surgery. Apart from effects on ossification, systemic and local EPO treatment leads to increased callus vascularization.

Risk factors for redisplacement in pediatric distal radius fractures after closed reduction and cast immobilisation

Introducation: Pediatric distal radius fractures are one of the most common fractures that we see in our practice. The primary modality of treatment of the displaced fractures of distal radius in children is closed reduction and immobilization in cast. Loss of alignment in cast after an acceptable reduction is common. Twenty one to fifty percent rates of redisplacement in cast after acceptable initial reduction have been reported in literature. Methods: This prospective study included 58 fractures of distal radius and distal third shaft of radius in 57 children with radiologically open physis. Age, gender, initial displacement, associated fracture of the ulna, adequacy of reduction, cast index and gap index were evaluated as possible risk factors for redisplacement in cast. Results: A redisplacement rate of 34.48%was found in distal radius fractures of children after acceptable initial closed reduction and immobilization in cast. Initial complete displacement, degree of initial translation in coronal and sagittal plane, degree of initial angulation in the coronal plane, associated fracture of the ulna, non anatomical initial reduction and cast index were found to be significant risk factors for redisplacement. Age, gender, initial angulation in the sagittal plane and gap index were insignificant risk factors. Conclusion: Distal radius fractures in children have high rate of redisplacement in cast. Fractures with initial complete displacement, fractures with associated fracture of ulna and non-anatomically reduced fractures should either be treated by primary closed reduction and percutaneous pinning or must be followed very carefully in cast treatment. Cast index rather than gap index is a better predictor of loss of reduction in cast.

Flexible Intramedullary Titanium Elastic Nailing of Fracture Shaft of Radius and Ulna in Children at a Tertiary Care Teaching Hospital

Introduction: Displaced fracture shaft of both bone forearms in children can still managed with close reduction and cast application. If, it has failed or remain inadequately reduced after closed reduction require intramedullary fixation to achieve functional outcome. This study assesses the functional outcome of treating displaced fracture shaft of both bone forearm in children with intramedullary flexible titanium elastic nailing.

Site-specific, adult bone benefits attributed to loading during youth: A preliminary longitudinal analysis

We examined site-specific bone development in relation to childhood and adolescent artistic gymnastics exposure, comparing up to 10years of prospectively acquired longitudinal data in 44 subjects, including 31 non-gymnasts (NON) and 13 gymnasts (GYM) who participated in gymnastics from pre-menarche to ≥1.9years post-menarche. Subjects underwent annual regional and whole-body DXA scans; indices of bone geometry and strength were calculated. Anthropometrics, physical activity, and maturity were assessed annually, coincident with DXA scans. Non-linear mixed effect models centered growth in bone outcomes at menarche and adjusted for menarcheal age, height, and non-bone fat-free mass to evaluate GYM-NON differences. A POST-QUIT variable assessed the withdrawal effect of quitting gymnastics. Curves for bone area, mass (BMC), and strength indices were higher in GYM than NON at both distal radius metaphysis and diaphysis (p<0.0001). At the femoral neck, greater GYM BMC (p<0.01), narrower GYM endosteal diameter (p<0.02), and similar periosteal width (p=0.09) yielded GYM advantages in narrow neck cortical thickness and buckling ratio (both p<0.001; lower BR indicates lower fracture risk). Lumbar spine and sub-head BMC were greater in GYM than NON (p<0.036). Following gymnastics cessation, GYM slopes increased for distal radius diaphysis parameters (p≤0.01) and for narrow neck BR (p=0.02). At the distal radius metaphysis, GYM BMC and compressive strength slopes decreased, as did slopes for lumbar spine BMC, femoral neck BMC, and narrow neck cortical thickness (p<0.02). In conclusion, advantages in bone mass, geometry, and strength at multiple skeletal sites were noted across growth and into young adulthood in girls who participated in gymnastics loading to at least 1.9years post-menarche. Following gymnastics cessation, advantages at cortical bone sites improved or stabilized, while advantages at corticocancellous sites stabilized or diminished. Additional longitudinal observation is necessary to determine whether residual loading benefits enhance lifelong skeletal strength.

A comparison of the effects of platelet-rich plasma and demineralized bone matrix on critical bone defects: An experimental study on rats.

Delayed union of fractured bone is one of the main problems of orthopedics and traumatology practice. It was hypothesized that the beneficial effects of allogeneic platelet-rich plasma (PRP) would be valuable in the treatment of segmental bone defects. This study is a comparison of the effects of demineralized bone matrix (DBM) and PRP in a segmental bone defect model. Total of 48 Wistar albino rats were separated into 4 groups. Segmental bone defect was created at right radius diaphysis in all specimens using dorsal approach. Four additional rats were used as PRP source. Intracardiac blood was withdrawn before the operation for preparation of allogeneic PRP. Group 1 (n=12) served as control group and defects were left untreated. Group 2 (n=12), was PRP group, and received grafting with PRP. Group 3 (n=12) was PRP+DBM combination group, and was treated with grafting and mixture of DBM and PRP. In Group 4 (n=12), defect area was grafted with DBM only. At the end of 10th week, rats were sacrificed, forearms were dissected, and defect areas were examined with radiological and histopathological parameters. Radiological evaluation revealed that ossification was best in PRP group, followed by DBM group. According to results of histopathological studies, union quality was better than control group in all treatment groups (Groups 2, 3, and 4), and was best in PRP group (p<0.05). Results were also better in PRP group when examined in terms of cortex development and remodeling (p<0.05). When examined in terms of new osteogenesis, results were comparable in Groups 2, 3, and 4, but all were better than control group. It was concluded that PRP and DBM have comparable effect on recovery of defective bones, but there is no synergistic effect when used together. We believe that PRP can be a cost-effective, readily available alternative to DBM with minimal morbidity.

Bone-Healing Capacity of PCL/PLGA/Duck Beak Scaffold in Critical Bone Defects in a Rabbit Model.

Bone defects are repaired using either natural or synthetic bone grafts. Poly(ϵ-caprolactone) (PCL), β-tricalcium phosphate (TCP), and poly(lactic-co-glycolic acid) (PLGA) are widely used as synthetic materials for tissue engineering. This study aimed to investigate the bone-healing capacity of PCL/PLGA/duck beak scaffold in critical bone defects and the oxidative stress status of the graft site in a rabbit model. The in vivo performance of 48 healthy New Zealand White rabbits, weighing between 2.5 and 3.5 kg, was evaluated. The rabbits were assigned to the following groups: group 1 (control), group 2 (PCL/PLGA hybrid scaffolds), group 3 (PCL/PLGA/TCP hybrid scaffolds), and group 4 (PCL/PLGA/DB hybrid scaffolds). A 5 mm critical defect was induced in the diaphysis of the left radius. X-ray, micro-CT, and histological analyses were conducted at (time 0) 4, 8, and 12 weeks after implantation. Furthermore, bone formation markers (bone-specific alkaline phosphatase, carboxyterminal propeptide of type I procollagen, and osteocalcin) were measured and oxidative stress status was determined. X-ray, micro-CT, biochemistry, and histological analyses revealed that the PCL/PLGA/duck beak scaffold promotes new bone formation in rabbit radius by inducing repair, suggesting that it could be a good option for the treatment of fracture.

Early clinical outcomes of isolated low velocity gunshot radius fractures treated with closed reduction and locked intramedullary nailing

BACKGROUND: The treatment goals in diaphyseal radius fractures are to regain and maintain length and rotational alignment and stability. Open reduction and plating carries the inherent problems of soft tissue disruption and periosteal stripping. Intramedullary nailing offers advantages of minimally invasive surgery and minimal soft tissue trauma. AIMS: To investigate the outcomes of locked intramedullary nailing for isolated gunshot diaphyseal radius fractures in adults. METHODS: A cross-sectional review of prospectively collected clinical and radiological data was performed. All adult patients with isolated gunshot radius fractures treated with closed reduction and locked intramedullary nailing between 2009 and 2013 were reviewed. Twenty-two nails were inserted in 22 patients, all males with a mean age of 28.9 years (range 19-40). All surgeries were performed between 2 and 12 days after injury (average 4 days). Follow-up was for an average of 11 weeks (range 8-24). RESULTS: All fractures united with the index procedure. Mean time to union was 10 weeks (range 8-24). Using the Anderson classification, the clinical outcome was excellent in 14 patients (64%), satisfactory in six (27%) and unsatisfactory in two (9%). CONCLUSION: Closed reduction and intramedullary nail fixation of gunshot radius fractures shows promising results without significant complications.

A Pronator Teres-sparing Volar Approach for Osteosynthesis of Midshaft Diaphyseal Radius Fractures.

Henry's approach is widely considered the "workhorse" for exposing the volar radius and has not really changed since his original description in 1945. We describe a pronator teres-sparing volar approach to the forearm, for osteosynthesis of midshaft diaphyseal radius fractures. We believe this approach is safe, simple, and reproducible, and has several practical and theoretical advantages over Henry's original description.

The missing effect of human recombinant Bone Morphogenetic Proteins BMP-2 and BMP-7 in surgical treatment of aseptic forearm nonunion

IntroductionIn this cohort study, the surgical revision concept of open compression plating and autologous bone grafting with and without additional application of BMP for treatment of aseptic ulna and/or radius shaft nonunion was evaluated. The purpose was to evaluate the clinical and radiological outcome, and to determine any difference in osseous healing, range of time between revision surgery and bone healing, and postoperative complications between the cohort groups. Patients and methodsBetween 01/2005 and 03/2015, a prospective, randomised, controlled cohort study was performed in a Level I Trauma Centre. Forty-nine patients were treated with the diagnosis of aseptic diaphyseal ulnar and/or radial shaft nonunion using compression plating and autologous bone grafting. Additional biological augmentation using BMP-2 or BMP-7 was performed in 24 patients. Clinical and radiological follow-up was performed six weeks, three and six months after revision surgery in accordance to the system by Anderson. ResultsThe study group consisted of 38 men and 11 women with a median age of 44 years (range 19–77). Twenty-four out of 49 patients obtained compression plating either with autologous iliac crest bone grafting (11/24 patients) or cancellous bone grafting (13/24 patients) and additional application of BMP-2 (4/24 patients) or BMP-7 (20/24 patients). The remaining 25 patients did not receive any additional application of BMP, but autologous bone grafting. The median follow-up was 15 months (range 6–54 months). Forty-six out of 49 nonunion healed within 12 months after revision surgery with a median time to union of six months. The clinical outcome, as assessed using the system by Anderson, as well as osseous healing, duration of time interval between revision surgery and bone healing, and postoperative complications did not demonstrate significant differences between the cohort groups. DiscussionAtrophic/oligotrophic forearm nonunion healed irrespective of additional application of BMP combined with autologous bone grafting. For successful treatment, radical resection of fibrous nonunion tissue and internal compression plate fixation is required with the aim of achieving high degree of rigid stability. Also, correction of angular deformities, restoration of length, and precise axial alignment of the distal radio-ulnar joint are mandatory prerequisites to successfully achieve bone healing.

Age-related changes in the fracture resistance of male Fischer F344 rat bone

In addition to the loss in bone volume that occurs with age, there is a decline in material properties. To test new therapies or diagnostic tools that target such properties as material strength and toughness, a pre-clinical model of aging would be useful in which changes in bone are similar to those that occur with aging in humans. Toward that end, we hypothesized that similar to human bone, the estimated toughness and material strength of cortical bone at the apparent-level decreases with age in the male Fischer F344 rat. In addition, we tested whether the known decline in trabecular architecture in rats translated to an age-related decrease in vertebra (VB) strength and whether non-X-ray techniques could quantify tissue changes at micron and sub-micron length scales. Bones were harvested from 6-, 12-, and 24-month (mo.) old rats (n=12 per age). Despite a loss in trabecular bone with age, VB compressive strength was similar among the age groups. Similarly, whole-bone strength (peak force) in bending was maintained (femur) or increased (radius) with aging. There was though an age-related decrease in post-yield toughness (radius) and bending strength (femur). The ability to resist crack initiation was actually higher for the 12-mo. and 24-mo. than for 6-mo. rats (notch femur), but the estimated work to propagate the crack was less for the aged bone. For the femur diaphysis region, porosity increased while bound water decreased with age. For the radius diaphysis, there was an age-related increase in non-enzymatic and mature enzymatic collagen crosslinks. Raman spectroscopy analysis of embedded cross-sections of the tibia mid-shaft detected an increase in carbonate subsitution with advanced aging for both inner and outer tissue.

An intra-bone axial load transducer: development and validation in an in-vitro radius model.

BackgroundAccurate measurement of forces through the proximal radius can assess the effects of some surgical procedures on radioulnar load sharing, but is difficult to achieve given the redundant loading nature of the musculoskeletal system. Previously reported devices have relied on indirect measurements that may alter articular joint location and function. An axial load transducer interposed in the diaphysis of the radius may accurately quantify unknown axial loads of the proximal radius, and maintain articular location.MethodsAn in-vitro radius model was developed by interposing an axial load transducer in the diaphysis of the proximal radius. Static loads of 20, 40, 60, 80, and 100 N were applied with a servo-hydraulic actuator to the native radial head at angles of 10°, 20°, 30°, and 40° in the anterior, posterior, medial and lateral directions.FindingsLinear regression of five repeatability trials showed excellent agreement between the transducer and applied loads (R2 = 1 for all trials). For off-axis net joint loads, the majority of measured loading errors were within the inter-quartile range for mean loads up to 80 N. Loads below 80 N and outside the inter-quartile range had errors of less than 1 N.ConclusionsThe repeatability and off-axis net joint load results of this study validate the effectiveness of the interposed axial load transducer to accurately quantify proximal radius loads. The surgical technique preserves the native articular location and soft-tissue constructs, like the annular ligament. The modular design allows for testing the effects of length-changing osteotomies in subsequent biomechanical studies.

Hyperbaric oxygen therapy improves angiogenesis and bone formation in critical sized diaphyseal defects.

Besides the use of autologous bone grafting several osteoconductive and osteoinductive methods have been reported to improve bone healing. However, persistent non-union occurs in a considerable number of cases and compromised angiogenesis is suspected to impede bone regeneration. Hyperbaric oxygen therapy (HBO) improves angiogenesis. This study evaluates the effects of HBO on bone defects treated with autologous bone grafting in a bone defect model in rabbits. Twenty-four New-Zealand White Rabbits were subjected to a unilateral critical sized diaphyseal radius bone defect and treated with autologous cancellous bone transplantation. The study groups were exposed to an additional HBO treatment regimen. Bone regeneration was evaluated radiologically and histologically at 3 and 6 weeks, angiogenesis was assessed by immunohistochemistry at three and six weeks. The additional administration of HBO resulted in a significantly increased new bone formation and angiogenesis compared to the sole treatment with autologous bone grafting. These results were apparent after three and six weeks of treatment. The addition of HBO therapy to autologous bone grafts leads to significantly improved bone regeneration. The increase in angiogenesis observed could play a crucial role for the results observed.