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β-Catenin-dependent Wnt signaling controls numerous aspects of skeletal development and postnatal bone repair. Currently available transgenic Wnt reporter mice allow for visualization of global canonical Wnt signaling activity within skeletal tissues, without delineation of cell type. This is particularly important in a bone repair context, in which the inflammatory phase can obscure the visualization of mesenchymal cell types of interest. To tackle the issue of tissue-specific Wnt signaling, we have generated and characterized a transgenic mouse strain [termed paired related homeobox 1 (Prx1)-Wnt-green fluorescent protein (GFP), by crossing a previously validated Prx1-Cre strain with a nuclear fluorescent reporter driven by T-cell factor/lymphoid enhancer factor activity (Rosa26-Tcf/Lef-LSL-H2B-GFP)]. Prx1-Wnt-GFP animals were subject to three models of long bone and membranous bone repair (displaced forelimb fracture, tibial cortical defect, and frontal bone defect). Results showed that, irrespective of bone type, locoregional mesenchymal cell activation of Wnt signaling occurs in a defined temporospatial pattern among Prx1-Wnt-GFP mice. In summary, Prx1-Wnt-GFP reporter animals allow for improved visualization, spatial discrimination, and facile quantification of Wnt-activated mesenchymal cells within models of adult bone repair.

Soft tissue sarcoma of the forearm, wrist and hand are rare. Their benign appearance leads often to primary inadequate treatment. Due to the complex anatomy of the hand and forearm, they are challenging to treat. The two goals are to obtain wide resection of the primary tumor while preserving function. Limb-sparing surgery is now the cornerstone for the treatment of most sarcomas of the forearm, hand and wrist. To achieve optimal oncological and functional outcomes, the surgical excision should be associated with early reconstructive procedures and a multidisciplinary meeting to define the treatment strategy including adjuvant medical treatments. This article outlines the current principles and presents the results of the treatment of soft tissue sarcomas with emphasis on to particularities related to their forearm, wrist and hand location.

Gorilla systematics has received increased attention over recent decades from primatologists, conservationists, and paleontologists. Studies of geographic variation in DNA, skulls, and teeth have led to new taxonomic proposals, such as recognition of two gorilla species, Gorilla gorilla (western gorilla) and Gorilla beringei (eastern gorilla). Postcranial differences between mountain gorillas ( G. beringei beringei ) and western lowland gorillas ( G. g. gorilla ) have a long history of study, but differences between the limb bones of the eastern and western species have not yet been examined with an emphasis on geographic variation within each species. In addition, proposals for recognition of the Cross River gorilla as Gorilla gorilla diehli and gorillas from Tshiaberimu and Kahuzi as G. b. rex-pymaeorum have not been evaluated in the context of geographic variation in the forelimb and hindlimb skeletons. Forty-three linear measurements were collected from limb bones of 266 adult gorillas representing populations of G. b. beringei , Gorilla beringei graueri , G. g. gorilla , and G. g. diehli in order to investigate geographic diversity. Skeletal elements included the humerus, radius, third metacarpal, third proximal hand phalanx, femur, tibia, calcaneus, first metatarsal, third metatarsal, and third proximal foot phalanx. Comparisons of means and principal components analyses clearly differentiate eastern and western gorillas, indicating that eastern gorillas have absolutely and relatively smaller hands and feet, among other differences. Gorilla subspecies and populations cluster consistently by species, although G. g. diehli may be similar to the eastern gorillas in having small hands and feet. The subspecies of G. beringei are distinguished less strongly and by different variables than the two gorilla species. Populations of G. b. graueri are variable, and Kahuzi and Tshiaberimu specimens do not cluster together. Results support the possible influence of higher-altitude Pleistocene refugia on patterns of geographic variation in gorillas.

Osteoporosis continues to be a major health condition plaguing the aging population. The major manifestation of osteoporosis, the development of fragility fractures, is a burden both clinically and economically on patients and the nation's health care system, with up to half of all American women sustaining a fragility fracture in their older years. The high frequency of injuries to the distal radius and proximal humerus should lead upper extremity surgeons to take pause and recognize the magnitude of impact these fractures have on their patient population. Recommended interventions span a spectrum of aggressiveness and have various financial implications.

Physical exercise during growth affects composition, structure and mechanical properties of bone. In this study we investigated whether the beneficial effects of exercise during the early growth phase have long-lasting effects or not. Female Syrian golden hamsters (total n=152) were used in this study. Half of the hamsters had access to running wheels during their rapid growth phase (from 1 to 3months of age). The hamsters were sacrificed at the ages of 1, 3, 12, and 15months. The diaphysis of the mineralized humerus was analyzed with microCT and subjected to three-point-bending mechanical testing. The trabecular bone in the tibial metaphysis was also analyzed with microCT. The collagen matrix of the humerus bone was studied by tensile testing after decalcification. The weight of the hamsters as well as the length of the bone and the volumetric bone mineral density (BMDvol) of the humerus was higher in the running group at the early age (3months). Moreover, the mineralized bone showed improved mechanical properties in humerus and had greater trabecular thickness in the subchondral bone of tibia in the runners. However, by the age of 12 and 15months, these differences were equalized with the sedentary group. The tensile strength and Young's modulus of decalcified humerus were higher in the runners at early stage, indicating a stronger collagen network. In tibial metaphysis, trabecular thickness was significantly higher for the runners in the old age groups (12 and 15months). Our study demonstrates that physical exercise during growth improves either directly or indirectly through weight gain bone properties of the hamsters. However, the beneficial effects were for the most part not maintained during aging.

Purpose The purpose of this study was to determine the incidence of osteonecrosis of appendicular bones due to nitrogen-containing intravenous bisphosphonates and the incidence of adverse effects in bones other than the jaws. Materials and Methods A detailed search of the professional medical and dental literature was conducted. In addition, a questionnaire was mailed to all known orthopedic surgery training programs in the United States. Programs were queried as to clinical findings and other various scenarios. Results There was a great paucity of literature that addressed the issue. Of the 154 questionnaires mailed, 29 (19%) were returned. Identification was optional; therefore, it was impossible to determine the geographic origin of the returned questionnaires. No orthopedic surgery training program indicated positive findings of osteonecrosis in the long bones due to nitrogen-containing intravenous bisphosphonates. There were rare reports in the literature of osteonecrosis in other areas of the bony skeleton. Conclusion On the basis of literature searches and national orthopedic questionnaires, there is only a rare incidence of osteonecrosis of the appendicular bones and bones other than the jaws due to nitrogen-containing intravenous bisphosphonates. There were no reports of adverse long bone effects, based on the questionnaires. There were rare reports in the literature.

Purpose Ulna longitudinal dysplasia is an uncommon congenital anomaly that demonstrates a wide variety of clinical manifestations. The clinical manifestations and function of patients with Bayne type IV ulna longitudinal dysplasia have not been well characterized. The purpose of this study was to report the clinical features of type IV ulna longitudinal dysplasia and the extent to which this affects a patient's ability to perform activities of daily living. Methods The medical records of children diagnosed with ulna longitudinal dysplasia in our institution between 1960 and 2004 were reviewed. The children found to have ulna longitudinal dysplasia with radiohumeral synostosis (Bayne type IV ulna dysplasia) were studied. The laterality of the deformity, associated musculoskeletal and nonmusculoskeletal anomalies, and treatments were recorded. Patients were interviewed regarding their ability to perform activities of daily living. Results One hundred twenty-five patients with 146 affected limbs were identified with ulna dysplasia. Seventeen limbs in 14 patients (12% of affected limbs) demonstrated radiohumeral synostosis (RHS). Three of 14 patients with RHS had bilateral involvement. The elbows were fixed in 20° to 90° of flexion. No elbows were positioned in full extension. Eleven of the 17 involved limbs with RHS had digital anomalies. Nine of the 17 limbs had surgical reconstruction. The majority of these procedures were performed on the hand. Conclusions The elbow, forearm, wrist, and hand clinical findings associated with type IV ulna longitudinal dysplasia are variable. Surgical treatment usually focuses on correction of hand abnormalities. Many patients function satisfactorily and are able to perform daily activities without surgical intervention. Type of study/level of evidence Diagnostic IV.

Skeletal responses to damage are significant for understanding the etiology of stress fractures and possibly osteoporotic fractures. We refined the rat forelimb-loading model to produce a range of sub-fracture damage levels during in vivo cyclic loading. A total of 98 right forelimbs of anesthetized, male, 5-month old Fischer rats were loaded cyclically (2 Hz) in axial compression. Rats were killed immediately after loading. In the first experiment, forelimbs were loaded to fracture, which occurred after an increase in peak displacement of 2.0±0.2 mm, independent of peak force or cycle number. In the next experiment, we loaded forelimbs at a constant peak force until the peak displacement increased by 0.6–1.8 mm (30–90% of fracture displacement). Mechanical properties of the loaded (right) and contralateral control (left) ulnae were determined ex vivo using three-point bending, and cracks were analyzed using micro-computed tomography. Results demonstrated a dose–response between increased forelimb displacement and increased ulnar damage, with four discrete damage levels. “Low” damage was produced by cyclic loading to 30% of fracture displacement, with no visible cracks and a 10% strength loss. “Mild” damage was produced by loading to 45% of fracture displacement, with variable linear cracks and 20% strength loss. “Moderate” damage was produced by loading to 60–75% of fracture displacement, with consistent linear cracks and 40% strength loss. “High” damage was produced by loading to 85–90% of fracture displacement, with branching cracks and 60% strength loss. This loading model will be useful for examining biological responses to a range of sub-fracture damage levels in future experiments.

Osteoid osteomas are benign tumors that may commonly mimic other entities in the upper extremity. The purpose of this study is to describe the clinical and imaging features of osteoid osteomas involving the upper extremity, highlight the difficulties in the diagnosis in the various areas and propose a diagnostic workup. Fourty-eight patients with histologically confirmed osteoid osteoma of the upper extremity treated at the authors' department from 1985 to 2000 were retrospectively reviewed. Data pertinent on the patients' history, lesion location, clinical and imaging characteristics as well as any unique features of individual patients were collected. There were 29 males and 19 females with a mean age of 28 years (range 20-42). The average duration of symptoms before definite diagnosis was 18 months (range 2-62). Pain was the presenting symptom in 46 of 48 patients, whereas swelling was the main complaint in 2 of the patients. Mean pre-operative visual analogue pain scale (VAS), was 8.8 ranging from 5.1 to 9.3. Eight lesions were located in the humerus, 4 in the ulna and 7 in the radius. In the carpal bones, 4 were located in the scaphoid, 4 in the capitate and 5 in the hamate. Seven lesions were located at the metacarpals and 9 lesions at the phalanges (5 proximal, no middle and 4 distal phalangeal lesions). Radiographs alone were sufficient to establish the diagnosis of osteoid osteoma in 32 cases. Bone scans identified a "hot spot" in 16 patients without previous radiographic evidence of a lesion and furthermore, computed tomography was performed in 32 patients to assist in the intraosseous localization of the lesion, and in the pre-operative planning. All patients underwent operative excision of the lesion and the diagnosis was confirmed by histology. Mean follow-up was 28 months (range 25-42). Fourty-three patients had an uneventful recovery. Mean post-operative VAS value was 1.8 ranging from 0 to 3. Osteoid osteoma of the upper extremity often mimics other etiologies and the complex anatomy of the upper extremity, as well as the tendency of patients to relate their symptoms to trauma are factors that easily lead to misdiagnosis or delay in the diagnosis. A high index of suspicion is essential and the diagnosis is based on an accurate clinical assessment and careful selection of imaging studies.

Although less common than lower-extremity stress fractures, upper-extremity stress fractures are becoming recognized much more frequently. A majority of these fractures are caused by overuse and fatigue of the surrounding musculature and, as a result, may be prevented by appropriate training and conditioning. Diagnosis is made by history and physical examination with the aid of plain radiographs, bone scans, and MRI. Most of these fractures heal with a period of relative rest followed by a structured rehabilitation program. A small percentage of these fractures, however, may require surgical fixation. The present article reviews the different types of upper extremity and torso stress fractures seen in athletes, starting with the sternum and extending outward to the fingers. The presentation, diagnosis, mechanism of injury, treatment, prevention, and prognosis for each of these injuries will be discussed.

Individuals with stroke have a high incidence of bone fractures and approximately 30% of these fractures occur in the upper extremity. The high risk of falls and the decline in bone and muscle health make the chronic stroke population particularly prone to upper extremity fractures. This was the first study to investigate the bone mineral content (BMC), bone mineral density (BMD), and soft tissue composition of the upper extremities and their relationship to stroke-related impairments in ambulatory individuals with chronic stroke (onset >1 year). Dual-energy X-ray absorptiometry (DXA) was used to acquire total body scans on 56 (22 women) community-dwelling individuals (>or=50 years of age) with chronic stroke. BMC (g) and BMD (g/cm2), lean mass (g), and fat mass (g) for each arm were derived from the total body scans. The paretic upper extremity was evaluated for muscle strength (hand-held dynamometry), impairment of motor function (Fugl-Meyer motor assessment), spasticity (Modified Ashworth Scale), and amount of use of the paretic arm in daily activities (Motor Activity Log). Results showed that the paretic arm had significantly lower BMC (13.8%, P

The aim of this study was to assess bone status in 220 subjects with end-stage renal failure (ESRF) (146 men, mean age 53.0 +/- 13.9 years and 74 women, mean age 48.1 +/- 14.3 years). The duration of hemodialysis (durHD) and duration of renal insufficiency (durRI) were, in men, 2.6 +/- 3.8 years and 7.7 +/- 8.0 years, and, in women, 2.8 +/- 3.4 years and 9.1 +/- 7.6 years, respectively. ESRF was caused by the following reasons: chronic glomerulonephritis in 92 patients, diabetes in 52, chronic pyelonephritis in 37, polycystic kidney disease in 19, amyloidosis in 5, hypertension in 4 and unknown cause in 11. The control group consisted of 1615 normal healthy subjects (1216 women, mean age 48.1 +/- 12.1 years and 399 men, mean age 52.9 +/- 14.8 years). Mean age did not differ between patients and controls. Skeletal status was evaluated by quantitative ultrasound (US) measurements at the hand phalanges using DBM 1200 (IGEA, Italy) which measures amplitude-dependent speed of sound (Ad-SoS, m/s). The mean value of Ad-SoS in male patients was 1981 +/- 88 m/s, T-score -l2.03 +/- 1.26, Z-score -0.53 +/- 1.7 and, in female patients, 1967 +/- 96 m/s, -2.23 +/- 1.37, -1.41 +/- 1.56, respectively. Respective values in male controls were 2008 +/- 81 m/s, -1.66 +/- 1.16, -0.01 +/- 0.98 and, in female controls, 2026 +/- 81 m/s, -1.4 +/- 1.15, -0.74 +/- 0.86, and were significantly higher than in male (p0.001) and female (p0.0000001) patients. A correlation analysis of Ad-SoS with durHD and durRI showed that only in males did both factors significantly influence parameters measured (r = -0.26, p0.01). Multiple stepwise regression analysis of Ad-SoS on age, durHD, durRI, weight and height was possible to perform only in males and the following equation was established: Ad-SoS = 2545 m/s - 3.09 x age (years) - 5.68 x durHD (years) - 2.15 x height (cm) - 0.99 x durRI (years), p0.000001, r = 0.55, SEE = 69.6. Concluding, in subjects with ESRF treated with hemodialysis, skeletal status assessed with the use of quantitative US was affected.

A comparative morphological analysis of human and non-human hominoids was conducted in an attempt to determine the mode of locomotion of the protohominid. Although the generalized hominoid anatomy permits variation of locomotion: brachiation, knuckle-walking, etc., minor variations in structure determine which behavior is favored. Arboreal arm swinging requires a flexible forelimb while terrestrial fist or knuckle-walking demands more rigidity of the hand and wrist. It is demonstrated that the large human thumb accompanied by the strong adduction of the thenar, hypothenar, and palmar interosseous muscles offer powerful rigidity to the hand, while fusion of the os centrale with the scaphoid during gestation permits the formation of an arch of carpals which imbue the wrist with the stability necessary for weight bearing. Fascialization of the contrahentes and dorsiepitrochlearis muscles in the human as well as depilation of the middle phalanges; the webbing (syndactyly) of the palm; the direction of the fibers of the interosseous membrane of the forearm; the shape of the puerile annular ligament, and the direction of the human glenoid fossa strongly suggest that the ancestor of man used a knuckle-walking form of locomotion prior to becoming bipedal. A model is presented that suggests that bipedalism was attained through an intermediate stage of tripedalism. The model is based on the fact that man's anatomy is much more asymmetric than that of the great apes. A presumption is made that due to the absence of trees for climbing in the transition from forest to open plain, the protohominid needed to carry tools (stones) at all times for protection. Stones could be carried for long distances on the posterior iliac crest since the weight would be shifted posteriorly over the legs. Pick up, medial rotation and adduction of the stone would employ a two-muscle chain of biceps brachii and latissimus dorsi. On the iliac crest, the stone is posterior to the coronal plane of the glenohumeral joint, and with the contraction of this two-muscle chain, the shoulder on one side is moved posteriorly effecting a semi-erect posture. It is proposed that tripedalism of the protohominid may be an explanation for the handedness unique to hominids.

Stress fractures are common injuries in the athletic population. Although much of the published literature has focused on lower extremity stress injuries, these injuries also occur in the upper extremities. Stress injuries of bone result from repetitive loads smaller than would be required to cause an acute fracture. As bone is repetitively stressed, it behaves like any solid substance. If deformity occurs within its elastic range, it returns to its original configuration. If stressed into its plastic range, permanent deformity occurs, and microfractures propagate, causing structural failure and complete fracture of the involved bone. High clinical suspicion is required for diagnosis because of historical and physical features can be vague. Plain radiographs are often inconclusive, but bone scans and MR imaging usually help elucidate the diagnosis. Most upper extremity stress injuries will heal with nonoperative management. In rare situations these injuries can progress to nonunion, which requires surgical correction.

The determination of sex and the estimation of stature from bones play an important role in identifying unknown bodies, parts of bodies or skeletal remains. In medico-legal practice statements on the probable sex of a decomposed body or part of a body are often expected even during autopsy. The present study was, therefore, restricted to few easily accessible dimensions from bones which were prepared only by mechanically removing soft tissues, tendons and ligaments. The specimens came from the Anatomical Institutes in Munich and Cologne from the years 1994-1998 including a total of 143 individuals (64 males and 79 females). The mean age was 79 years (46-108), the mean body height 161cm (134-189). The following measurements were taken: maximum humeral length (mean: 33.4cm in males; 30.7cm in females), vertical humeral head diameter (mean: 5.0cm in males, 4.4cm in females), humeral epicondylar width (mean: 6.6cm in males; 5.8cm in females), maximum ulnar length (mean: 26.5cm in males, 23.8cm in females), proximal ulnar width (mean: 3.4cm in males, 2.9cm in females), distal ulnar width (mean: 2.2cm in males; 1.8cm in females), maximum radial length (mean: 24.6cm in males; 22.0cm in females), radial head diameter (mean: 2.6cm in males, 2.2cm in females) and distal radial width (mean: 3.6cm in males; 3.2cm in females). The differences between the means in males and females were significant (P

This study used 110 CT images taken from donated Korean cadavers to create 3-D models of the following upper and lower limb bones: the clavicle, scapula, humerus, radius, ulna, hip bone (os coxa), femur, patella (knee cap), tibia, talus, and calcaneus. In addition, the bone volume and surface area were calculated to determine sex differences using discriminant analysis. Significant sex differences were found in all bones with respect to volume and surface area (p0.01). The order of volume was the same in females and males (femurhip bonetibiahumerusscapula), although the order of surface area was different. The largest surface area in men was the femur and in women was the hip bone (p0.01). An interesting finding of this study was that the ulna is the bone with the highest accuracy for sex determination (94%). When using the surface area of multiple bones, the maximum accuracy (99.4%) was achieved. The equation was as follows: (discriminant equation of surface area; female0male)=0.060×clavicle+0.020×scapula+0.045×humerus+(-0.049)×radius+0.093×ulna+(-0.023)×hip bone+0.091×patella+(-0.052)×fibula+0.043×talus-11.548. These results show that bone volume and surface area of extremity bones can be used for sex determination.