Radiographic evaluation of the forelimb bone development in maned wolves (Chrysocyon brachyurus).

This study aimed to assess the fusion of growth plates and the development of secondary ossification centres in the forelimb bones of maned wolves (Chrysocyon brachyurus), contrasting the findings with established data from domestic dogs. Three maned wolves, comprising one male and two females, initially aged between 3 and 4 months, were subjected to monthly radiographic evaluations until 10-11 months of age, followed by bimonthly assessments until 18-19 months of age, encompassing both forelimbs. The closure times of growth plates were observed as follows: supraglenoid tubercle (7-8 months), proximal humerus (17-19 months), distal humerus (8-9 months), medial epicondyle of the humerus (8-9 months), proximal ulna (9-10 months), proximal radius (13-15 months), distal ulna (13-15 months) and distal radius (17-19 months). Statistical analysis revealed significant differences in the areas of secondary ossification centres in the proximal epiphyses of the humerus and radius, respectively, observed from the initial evaluation at 8-9 months and 6-7 months. Conversely, the epiphyses of the supraglenoid tubercle, distal humerus, proximal ulna, distal ulna, medial epicondyle of the humerus and distal radius did not exhibit significant area differences between 3-4 months and 4-5 months, yet notable distinctions emerged at 5-6 months. In summary, while the radiographic appearance of epiphyseal growth plates and secondary ossification centres in maned wolves resembles that of domestic dogs, closure times vary. These findings contribute to understanding the dynamics of epiphyseal growth plates in this species.

Effect of the Sauvé-Kapandji method on the wrist contact surface for distal radial ulnar joint disorders.

BACKGROUND: The Sauvé-Kapandji (S-K) method is a surgical procedure performed for chronic deformities of the distal radial ulnar joint (DRUJ). Changes to the joint contact surface from pre- to postoperatively under physiological in vivo conditions have not yet been determined for this useful treatment. The aim of the present study was therefore to compare the articular contact area of the wrist joint between before and after the S-K method for DRUJ disorders. METHODS: The SK method was performed for 15 patients with DRUJ osteoarthritis and ulnar impaction syndrome. We calculated the Mayo Wrist Score as the patient's clinical findings and created 3-dimensional bone models of cases in which the S-K method was performed and calculated the contact area and shift in the center of the contact area using customized software. RESULTS: The Mean modified Mayo Wrist Score improved significantly from 60.3 preoperatively to 80.3 postoperatively (P < 0.01). Scaphoid contact area to the radius increased significantly from 112.6 ± 37.0 mm2 preoperatively to 127.5 ± 27.8 mm2 postoperatively (P = 0.03). Lunate contact area to radius-ulna was 121.3 ± 43.3 mm2 preoperatively and 112.5 ± 37.6 mm2 postoperatively, but this decrease was not significant (P = 0.38). Contact area ratio of scaphoid to lunate increased significantly from 1.01 ± 0.4 preoperatively to 1.20 ± 0.3 postoperatively (P = 0.02). Postoperative translations of the center of the scaphoid and lunate contact areas were decomposed into ulnar and proximal directions. Ulnar and proximal translation distances of the scaphoid contact area were 0.8 ± 1.7 mm and 0.4 ± 0.6 mm, respectively, and those of the lunate contact area were 1.1 ± 1.7 mm and 0.4 ± 1.1 mm, respectively. This study revealed changes in wrist contact area and center of the contact area before and after the S-K method. CONCLUSION: These results may accurately indicate changes in wrist joint contact area from pre- to postoperatively using the S-K method for patients with DRUJ disorder. Evaluation of changes in contact area due to bone surface modeling of the wrist joint using 3DCT images may be useful in considering surgical methods.

An Automatic Method for Elbow Joint Recognition, Segmentation and Reconstruction.

Elbow computerized tomography (CT) scans have been widely applied for describing elbow morphology. To enhance the objectivity and efficiency of clinical diagnosis, an automatic method to recognize, segment, and reconstruct elbow joint bones is proposed in this study. The method involves three steps: initially, the humerus, ulna, and radius are automatically recognized based on the anatomical features of the elbow joint, and the prompt boxes are generated. Subsequently, elbow MedSAM is obtained through transfer learning, which accurately segments the CT images by integrating the prompt boxes. After that, hole-filling and object reclassification steps are executed to refine the mask. Finally, three-dimensional (3D) reconstruction is conducted seamlessly using the marching cube algorithm. To validate the reliability and accuracy of the method, the images were compared to the masks labeled by senior surgeons. Quantitative evaluation of segmentation results revealed median intersection over union (IoU) values of 0.963, 0.959, and 0.950 for the humerus, ulna, and radius, respectively. Additionally, the reconstructed surface errors were measured at 1.127, 1.523, and 2.062 mm, respectively. Consequently, the automatic elbow reconstruction method demonstrates promising capabilities in clinical diagnosis, preoperative planning, and intraoperative navigation for elbow joint diseases.

Automated Determination of Morphometric Parameters of the Human Radius Based on the Results of Its Computed Tomography.

A fundamentally new software method for automated measurement of morphometric parameters of computed tomographic image of the human radius has been designed. The parameters obtained by manual morphometry of computed tomograms using the RadiAnt DICOM Viewer software were compared with the results of the software product developed by us. The relative error in the measurement of morphometric parameters was about 10%. In the future, the presented software method of automated determination of morphometric parameters of the bone will enable modeling of individual prosthesis of the head of the radius based on the results of computed tomograms with consideration of the structural features of the human radius.

Use of F18 bioglass putty for induced membrane technique in segmental bone defect of the radius in rabbits.

PURPOSE: To evaluate the inductive capacity of F18 bioglass putty on the induced membrane technique in a segmental bone defect of the rabbit's radius. METHODS: Ten female Norfolk at 24 months of age were used. The animals were randomly separated based on postoperative time points: five rabbits at 21 and four at 42 days. A 1-cm segmental bone defect was created in both radii. The bone defects were filled with an F18 bioglass putty. RESULTS: Immediate postoperative radiographic examination revealed the biomaterial occupying the segmental bone defect as a well-defined radiopaque structure with a density close to bone tissue. At 21 and 42 days after surgery, a reduction in radiopacity and volume of the biomaterial was observed, with particle dispersion in the bone defect region. Histologically, the induced membrane was verified in all animals, predominantly composed of fibrocollagenous tissue. In addition, chondroid and osteoid matrices undergoing regeneration, a densely vascularized tissue, and a foreign body type reaction composed of macrophages and multinucleated giant cells were seen. CONCLUSIONS: the F18 bioglass putty caused a foreign body-type inflammatory response with the development of an induced membrane without expansion capacity to perform the second stage of the Masquelet technique.

Conservative treatment of congenital radial head subluxation and non-traumatic elbow locking: A case report.

Congenital radial head subluxation is relatively rare and may be overlooked due to mild symptoms. The diagnosis mainly relies on imaging and history. Observation is an option for those with insignificant symptoms, while surgical intervention, such as ulnar osteotomy or arthroscopy, is often required when dysfunction exists. A 30-year-old man was admitted with congenital radial head dislocation, which was treated with manipulative repositioning. During follow-up, the patient regained the original mobility of the elbow joint and had no recurrence of dislocation. In conclusion, in adults with congenital dislocation of the radial head, we recommend conservative treatment as a first step.

Stress shielding following radial head arthroplasty: the impact of preoperative bone quality.

BACKGROUND: We sought to assess if the medullary diameter to cortical width ratio (MD:CW), canal flair index (CFI), and canal fill (CF) of the proximal radius were associated with the presence of stress shielding (SS) after a MoPyC radial head arthroplasty. MATERIALS AND METHODS: We conducted a retrospective, international, multicenter (4 centers) study. A total of 100 radial head arthroplasties in 64 women and 36 men with a mean age of 58.40 years ± 14.90 (range, 25.00-91.00) were included. Radiographic measurements, including MD:CW, CFI, CF, and postoperative SS were captured at a mean follow-up of 3.9 years ± 2.8 (range, 0.5-11). RESULTS: SS was identified in 60 patients. Mean preoperative MD:CW, CFI, and CF were 0.55 ± 0.09, 1.05 ± 0.18, and 0.79 ± 0.11, respectively. The presence of SS was significantly associated with MD:CW (adjusted odds ratio = 13.66; P = .001), and expansion of the stem (adjusted odds ratio = 3.78; P = .001). The amount of the SS was significantly correlated with expansion of the stem (aß 4.58; P < .001). CONCLUSIONS: Our study found that MD:CW was an independent risk factor of SS after MoPyc radial head arthroplasty. Autoexpansion of the MoPyc stem significantly increased the risk of SS and its extent. Further studies involving multiple implants designs are needed to confirm the preliminary observations presented in the current study.

Nursemaid's elbow: Radial head subluxation injuries in children.

ABSTRACT: Radial head subluxation, or nursemaid's elbow, is a common orthopedic complaint in children and often is the result of a pulling injury to the affected arm. Although this injury largely is a clinical diagnosis, different imaging modalities may be used to identify it and confirm successful reduction. Multiple manipulative techniques can be used to treat this injury and methods are generally specific to clinician preference. This article reviews the causes, evaluation, and management of radial head subluxation.

Long-term follow-up for the atypical radial longitudinal deficiency: A case report.

We experienced an atypical case of radial longitudinal deficiency that did not fit into any classifications, including Blauth. The patient had a bilateral hypoplastic thumb, in which the index and middle fingers were missing in the right hand. We performed surgeries in four stages: centralization of the right hand, opponensplasty of the right thumb, opponensplasty of the left thumb, and distraction lengthening of the right ulnar. Twenty-five years after the initial treatment, the patient was satisfied with the treatment and had no significant difficulty with activities of daily living.

Osteoid osteoma of the distal radius presenting as an inconspicuous swelling in a young child.

Osteoid osteoma is a benign osteoblastic tumour with a predilection for the lower extremity that rarely affects the forearm. It is commonly seen in adolescents and young adults, and is seldom diagnosed in the paediatric age group. We report a boy in his early childhood who presented with a swelling over the distal forearm, which was incidentally noted by the mother 3 months ago. Plain radiographs showed diffuse sclerosis of the dorsal cortex of the distal radius. CT scan showed a central lucent nidus in the intramedullary region and surrounding sclerosis in the radial metaphysis, confirming the diagnosis of osteoid osteoma. The patient was successfully treated by surgical en bloc resection of the nidus and was asymptomatic at 1-year follow-up. Non-specific symptoms at presentation make it a challenge to diagnose osteoid osteoma in children and it needs to be considered in the differential diagnosis when radiographs show lytic lesions in the bone.

Digital smart internal fixation surgery for coronal process basal fracture with normal joint spaces or radius-shortening: Occult factor of radius-ulna load sharing.

BACKGROUND: Reasonable postoperative humeroradial and humeroulnar joint spaces maybe an important indicator in biomechanical stability of smart internal fixation surgery for coronoid process basal fractures (CPBF). The aim of this study is to compare elbow articular stresses and elbow-forearm stability under smart internal fixations for the CPBF between normal elbow joint spaces and radius-shortening, and to determine the occult factor of radius-ulna load sharing. METHODS: CT images of 70 volunteers with intact elbow joints were retrospectively collected for accurate three-dimensional reconstruction to measure the longitudinal and transverse joint spaces. Two groups of ten finite element (FE) models were established prospectively between normal joint space and radius-shortening with 2.0 mm, including intact elbow joint and forearm, elbow-forearm with CPBF trauma, anterior or posterior double screws-cancellous bone fixation, mini-plate-cancellous bone fixation. Three sets of physiological loads (compression, valgus, varus) were used for FE intelligent calculation, FE model verification, and biomechanical and motion analysis. RESULTS: The stress distribution between coronoid process and radial head, compression displacements and valgus angles of elbow-forearm in the three smart fixation models of the normal joint spaces were close to those of corresponding intact elbow model, but were significantly different from those of preoperative CPBF models and fixed radius-shortening models. The maximum stresses of three smart fixation instrument models of normal joint spaces were significantly smaller than those of the corresponding fixed radius-shortening models. CONCLUSIONS: On the basis of the existing trauma of the elbow-forearm system in clinical practice, which is a dominant factor affecting radius-ulna load sharing, the elbow joint longitudinal space has been found to be the occult factor affecting radius-ulna load sharing. The stability and load sharing of radius and ulna after three kinds of smart fixations of the CPBF is not only related to the anatomical and biomechanical stability principles of smart internal fixations, but also closely related to postoperative elbow joint longitudinal space.

Fracture risk based on high-resolution peripheral quantitative computed tomography measures does not vary with age in older adults-the bone microarchitecture international consortium prospective cohort study.

Fracture risk increases with lower areal bone mineral density (aBMD); however, aBMD-related estimate of risk may decrease with age. This may depend on technical limitations of 2-dimensional (2D) dual energy X-ray absorptiometry (DXA) which are reduced with 3D high-resolution peripheral quantitative computed tomography (HR-pQCT). Our aim was to examine whether the predictive utility of HR-pQCT measures with fracture varies with age. We analyzed associations of HR-pQCT measures at the distal radius and distal tibia with two outcomes: incident fractures and major osteoporotic fractures. We censored follow-up time at first fracture, death, last contact or 8 years after baseline. We estimated hazard ratios (HR) and 95%CI for the association between bone traits and fracture incidence across age quintiles. Among 6835 men and women (ages 40-96) with at least one valid baseline HR-pQCT scan who were followed prospectively for a median of 48.3 months, 681 sustained fractures. After adjustment for confounders, bone parameters at both the radius and tibia were associated with higher fracture risk. The estimated HRs for fracture did not vary significantly across age quintiles for any HR-pQCT parameter measured at either the radius or tibia. In this large cohort, the homogeneity of the associations between the HR-pQCT measures and fracture risk across age groups persisted for all fractures and for major osteoporotic fractures. The patterns were similar regardless of the HR-pQCT measure, the type of fracture, or the statistical models. The stability of the associations between HR-pQCT measures and fracture over a broad age range shows that bone deficits or low volumetric density remain major determinants of fracture risk regardless of age group. The lower risk for fractures across measures of aBMD in older adults in other studies may be related to factors which interfere with DXA but not with HR-pQCT measures.

In vivo research on 3D-printed composite PLGA and PDLLA-HA absorbable scaffolds for repairing radius defects in rabbits.

OBJECTIVES: Despite being an important research topic in oral biomaterials, few studies have demonstrated the differences between poly(d,l-lactide-co-glycolide)/hydroxyapatite (PLGA/HA) and poly(d,l-lactic acid)/hydroxyapatite (PDLLA/HA). In this study, PLGA/HA and PDLLA/HA scaffolds were prepared using three-dimensional (3D) printing technology and implanted into radius defects in rabbits to assess their effects on bone regeneration. METHODS: In this study, 6 mm × 4 mm bone defects were generated in the bilateral radii of rabbits. 3D-printed PLGA/HA and PDLLA/HA scaffolds were implanted into the defects. X-ray imaging, micro-computed tomography, and hematoxylin-eosin staining were performed to observe the degradation of the materials, the presence of new bone, and bone remodeling in the bone defect area. RESULTS: The PLGA/HA scaffolds displayed complete degradation at 20 weeks, whereas PDLLA/HA scaffolds exhibited incomplete degradation. Active osteoblasts were detected in both groups. The formation of new bone, bone marrow cavity reconstruction, and cortical bone remodeling were better in the PLGA/HA group than in the PDLLA/HA group. CONCLUSIONS: PLGA/HA scaffolds performed better than PDLLA/HA scaffolds in repairing bone defects, making the former scaffolds more suitable as bone substitutes at the same high molecular weight.

Bone microarchitecture and strength assessment in adults with osteogenesis imperfecta using HR-pQCT: normative comparison and challenges.

Data on bone microarchitecture in osteogenesis imperfecta (OI) are scarce. The aim of this cross-sectional study was to assess bone microarchitecture and strength in a large cohort of adults with OI using high-resolution peripheral quantitative computed tomography (HR-pQCT) and to evaluate challenges of using HR-pQCT in this cohort. Second-generation HR-pQCT scans were obtained at the distal radius and tibia in 118 men and women with Sillence OI type I, III, or IV using an extremity-length-dependent scan protocol. In total, 102 radius and 105 tibia scans of sufficient quality could be obtained, of which 11 radius scans (11%) and 14 tibia scans (13%) had a deviated axial scan angle as compared with axial angle data of 13 young women. In the scans without a deviated axial angle and compared with normative HR-pQCT data, Z-scores at the radius for trabecular bone mineral density (BMD), number, and separation were -1.6 ± 1.3, -2.5 ± 1.4, and -2.7 (IQR: 2.7), respectively. They were -1.4 ± 1.5 and -1.1 ± 1.2 for stiffness and failure load and between ±1 for trabecular thickness and cortical bone parameters. Z-scores were significantly lower for total and trabecular BMD, stiffness, failure load, and cortical area and thickness at the tibia. Additionally, local microarchitectural inhomogeneities were observed, most pronounced being trabecular void volumes. In the scans with a deviated axial angle, the proportion of Z-scores <-4 or >4 was significantly higher for trabecular BMD and separation (radius) or most total and trabecular bone parameters (tibia). To conclude, especially trabecular bone microarchitecture and bone strength were impaired in adults with OI. HR-pQCT may be used without challenges in most adults with OI, but approximately 12% of the scans may have a deviated axial angle in OI due to bone deformities or scan positioning limitations. Furthermore, standard HR-pQCT parameters may not always be reliable due to microarchitectural inhomogeneities nor fully reflect all inhomogeneities.

OI is a rare condition with large clinical heterogeneity. One of the major characteristics associated with OI is the increased fracture risk due to defects in bone structure and material. Data on the defects in bone structure at the micrometer level (i.e. bone microarchitecture) are scarce. Bone microarchitecture can be assessed noninvasively using HR-pQCT, but its use in OI has not extensively been described. Yet, potential challenges may arise related to among others the occurrence of short extremities and skeletal deformities in OI. We assessed bone microarchitecture and strength in 118 adults with OI types I, III, or IV using HR-pQCT with an extremity-length-dependent scan protocol. Additionally, we evaluated potential challenges of using HR-pQCT in this cohort. Our results demonstrated that predominantly trabecular microarchitecture­especially trabecular number and separation­and overall bone strength were impaired in adults with OI as compared with normative data. Furthermore, we observed various microarchitectural inhomogeneities, most pronounced being trabecular void volumes. Regarding applicability, HR-pQCT could be used without challenges in most adults with OI. However, deviations in scan region may potentially influence HR-pQCT parameters, and standard HR-pQCT analyses may not always give accurate results due to microarchitectural inhomogeneities nor fully reflect all microarchitectural inhomogeneities.

Measurement of Radiological Parameters of Distal Radius Fracture Using the Ulnar Axis Compared with the Radial Axis.

Background: The long axis of the radius is a standard reference for measuring radiological parameters in distal radius fractures. However, in patients with severe comminution and anatomical variation with distal radius bowing, it is challenging to assess using the long axis of the radius. The long axis of the ulna can be used as an alternative reference. The aim of this study is to assess the reliability and level of agreement using the long axis of the ulna as an alternative reference in comparison to the long axis of the radius. Methods: Posteroanterior (PA) radiography of the wrist in patients with acute distal radius fractures was evaluated in two rounds by four observers. Radial height, radial inclination and ulnar variance were measured using radial and ulnar long axis as references. The intraobserver and interobserver reliability of the measurements with two reference axes was assessed using intraclass correlation coefficient (ICC). The level of agreement was determined using the Bland-Altman plot. Results: In total, 59 patients who underwent PA radiography of the wrist were included in this study. All parameters exhibited good agreement between the two methods, with a mean difference of nearly zero (radial height = -0.03 mm, radial inclination = -0.14° and ulnar variance = 0.03 mm). The limits of agreement in radial height (-2.87, 2.82 mm) and ulnar variance (-0.81, 0.87 mm) were narrow. However, for the radial inclination, it was wider (-6.21, 5.94°). Intraobserver reliability between the long axis of radius and ulna (ICC = 0.85-0.99 and 0.84-0.98, respectively) was good to excellent. The interobserver reliability of each parameter was excellent (ICC = 0.94-0.97). Conclusions: The ulnar long axis can be used as an alternative reference for measuring radial height, radial inclination and ulnar variance in PA radiography of the wrist in acute distal radius fracture, particularly if the radial long axis is distorted. Level of Evidence: Level III (Diagnostic).

Does simultaneous comminuted fracture of both radial ends represent a distinct fracture pattern?

BACKGROUND: Although isolated distal radius and radial head fractures are common injuries, simultaneous ipsilateral fractures are uncommon. They can range from simple undisplaced fractures at either end to severely comminuted ipsilateral proximal and distal radial fractures. Few cases have been reported with concomitant comminuted distal radius and radial head fractures, and no treatment guidelines are available. Decisions are often based on personal recommendations. The purpose of our study is to increase awareness of this injury pattern and to discuss the mechanism of injury, treatment approach, and functional outcome. METHODS: Skeletally mature patients with comminuted simultaneous ipsilateral fractures of the distal and proximal radius from 2016 to 2021 were identified and studied retrospectively. Demographic information, mechanism of injury, treatment approach, and complication rate were analyzed. Radiographic assessment for inadequacy or loss of reduction and radiographic parameters of the distal radius, including radial inclination, radial length, and palmar inclination, was performed immediately postoperatively and at the final follow-up. Clinical outcomes were determined by calculating the Visual Analog Scale (VAS) score, measuring the range of motion in both joints, and using the Quick Disabilities of the Arm, Shoulder and Hand (QuickDASH) score at the final follow-up. RESULTS: A total of 11 patients met the inclusion criteria. All had ipsilateral Mason III radial head fractures and type C (according to the Arbeitsgemeinschaft für Osteosynthesefragen (AO) classification) intra-articular distal radius fracture. On-table radial head reconstruction and fixation with a proximal radius plate were used for radial head fractures, and osteosynthesis with an anatomic volar locking plate was used for distal radius fractures. The mean follow-up duration was 32 months (range 12-65 months). At the final follow-up, osseous union of both the radial head and distal radius was observed in all patients. The mean VAS score was 1.5 (range 0-7) at rest and 3.9 (range 0-9) with activities, while the mean QuickDASH score was 32 (range 12-65). No significant complications were recorded. CONCLUSION: Simultaneous comminuted fractures of the ipsilateral distal radius and radial head represent a distinct injury pattern, most likely resulting from high-energy trauma, such as falling from a height onto an outstretched hand. Greater emphasis should be placed on clinical examination and radiological imaging of the elbow in cases of wrist injuries and vice versa. Treatment involving on-table reconstruction of the radial head and open reduction and internal fixation with a volar plate can lead to good radiological and functional outcomes.

Prunes preserve cortical density and estimated strength of the tibia in a 12-month randomized controlled trial in postmenopausal women: The Prune Study.

Non-pharmacological therapies, such as whole-food interventions, are gaining interest as potential approaches to prevent and/or treat low bone mineral density (BMD) in postmenopausal women. Previously, prune consumption preserved two-dimensional BMD at the total hip. Here we demonstrate that prune consumption preserved three-dimensional BMD and estimated strength at the tibia. PURPOSE: Dietary consumption of prunes has favorable impacts on areal bone mineral density (aBMD); however, more research is necessary to understand the influence on volumetric BMD (vBMD), bone geometry, and estimated bone strength. METHODS: This investigation was a single center, parallel arm 12-month randomized controlled trial (RCT; NCT02822378) to evaluate the effects of 50 g and 100 g of prunes vs. a Control group on vBMD, bone geometry, and estimated strength of the radius and tibia via peripheral quantitative computed tomography (pQCT) in postmenopausal women. Women (age 62.1 ± 5.0yrs) were randomized into Control (n = 78), 50 g Prune (n = 79), or 100 g Prune (n = 78) groups. General linear mixed effects (LME) modeling was used to assess changes over time and percent change from baseline was compared between groups. RESULTS: The most notable effects were observed at the 14% diaphyseal tibia in the Pooled (50 g + 100 g) Prune group, in which group × time interactions were observed for cortical vBMD (p = 0.012) and estimated bone strength (SSI; p = 0.024); all of which decreased in the Control vs. no change in the Pooled Prune group from baseline to 12 months/post. CONCLUSION: Prune consumption for 12 months preserved cortical bone structure and estimated bone strength at the weight-bearing tibia in postmenopausal women.

Developmental Anatomy of the Radial Bow in Pediatric Patients Using 3D Imaging.

BACKGROUND: While radial bow shape is well characterized in adults, its development in children is not well understood. Previous studies on the radial bow use radiographs, thus, rotational positioning of the forearm could alter bowing measurements. This study used 3D imaging to better assess the pediatric radial bow. METHODS: Computed tomography scans from the New Mexico Decedent Image Database were obtained for ages 2 to 16 (females) and 18 (males) (n=152). 3D models were generated using Slicer and Rhino software. Length of the entire radial bow (bicipital tuberosity to sigmoid notch), maximum radial bow, location of the maximum radial bow (bicipital tuberosity to the point of maximum bowing), and distal, middle, and proximal third radial bows were measured. RESULTS: The length of the entire bow increased with age, with a strong correlation with age ( r =0.90, P <0.01). The maximum bow increased with age, with a strong correlation with age ( r =0.78, P <0.01). The maximum bow normalized to the length of the entire bow increased mildly with age, mean 0.059 ± 0.012 ( r =0.24, P =0.0024), but seems to plateau around age 8. The location of the maximum bow increased with age ( r =0.85, P <0.01). The normalized location of the maximum bow remained constant between ages, with a mean of 0.41 ± 0.10 ( r =0.12, P =0.14). The normalized distal third bow mildly increased with age ( r =0.34, P <0.01), the normalized middle third bow mildly increased with age ( r =0.25, P <0.01), and the normalized proximal third bow remained constant between ages ( r =0.096, P =0.24). CONCLUSIONS: Normalized values for maximum, distal third, and middle third radial bow increase with age, while normalized values for location and proximal third radial bow remain relatively constant, suggesting the proportional shape of the radius changes during development, although qualitatively plateaus after age 8. LEVEL OF EVIDENCE: Retrospective comparative study, Level-III.