The objective of this study was to investigate how a new customizable light-curable osteosynthesis method (AdFix) compared to traditional metal hardware when loaded in torsion in an ovine phalanx model. Twenty-one ovine proximal phalanges were given a 3mm transverse osteotomy and four 1.5mm cortex screws were inserted bicortically on either side of the gap. The light-curable polymer composite was then applied using the method developed by Hutchinson [1] to create osteosyntheses in two groups, having either a narrow (6mm, N=9) or a wide (10mm, N=9) fixation patch. A final group (N=3) was fixated with conventional metal plates. The constructs were loaded in torsion at a rate of 6°/second until failure or 45° of rotation was reached. Torque and angular displacement were measured, torsional stiffness was calculated as the slope of the Torque-Displacement curve, and maximum torque was queried for each specimen. The torsional stiffnesses of the narrow, wide, and metal plate constructs were 39.1 ± 6.2, 54.4 ± 6.3, and 16.2 ± 3.0 Nmm/° respectively. All groups were statistically different from each other (p<0.001). The maximum torques of the narrow, wide, and metal plate constructs were 424 ± 72, 600 ± 120, and 579 ± 20 Nmm respectively. The narrow constructs were statistically different from the other two (p<0.05), while the wide and metal constructs were not statistically different from each other (p=0.76). This work demonstrated that the torsional performance of the novel solution is comparable to metal fixators. As a measure of the functional range, the torsional stiffness in the AdhFix exceeded that of the metal plate. Furthermore, the wide patches were able to sustain a similar maximum toque as the metal plates. These results suggest AdhFix to be a viable, customizable alternative to metal implants for fracture fixation in the hand

Introduction. When designing a new osteosynthesis device, the biomechanical competence must be evaluated with respect to the acting loads. In a previous study, the loads on the proximal phalanx during rehabilitation exercises were calculated. This study aimed to assess the safety of a novel customizable osteosynthesis device compared to those loads to determine when failure would occur. Method. Forty proximal phalanges were dissected from skeletally mature female sheep and divided into four testing groups. A custom 3D printed cutting and drilling guide was used to create a reduced osteotomy and pilot holes to insert four 1.5 mm cortical screws. A novel light-curable polymer composite was used to fixate the bones with an in situ fixation patch. The constructs were tested in cyclic four-point bending in a bioreactor with ringer solution at 37°C with a valley load of 2 N. Four groups (N = 10) had increasing peak loads based on varying safety factors relative to the physiological loading (G1:100x, G2:150x, G3:175x, G4:250x). Each specimen was tested for 12,600 cycles (6 weeks of rehabilitation) or until failure occurred. After the test the thickness of the patch was measured with digital calipers and data analysis was performed in Python and R. Result. All samples survived in G1, and all failed in G4. G2 and G3 had 1 and 8 failures, respectively. There was no significant difference in patch thickness in all survivor samples against failures (p = 0.131), however, there was a significant difference in the displacement amplitude in the final cycle (0.072 mm vs. 0.15 mm; p < 0.001). Conclusion. This study found the survival and failure limits of a novel osteosynthesis device as a function of physiological loading. These results indicate that such fixations could withstand 100x the loading for typical non-weightbearing rehabilitation. Further studies are needed to confirm the safety for other conditions

Extensor tendon attachment to the dorsum of the proximal phalanx may fully extend the finger metacarpal phalangeal joint (MPJ). 15 fresh-frozen cadaveric hands were axially loaded in the line of pull to the extensor digitorum comunis of the index, middle, ring and small finger at the level just proximal to the MPJ. We measured force of extension at the MP joint in 3 groups: 1) native specimen, 2) extensor tendon release at the proximal interphalangeal (PIP) joint with release of lumbricals/lateral bands, 3) extensor tendon release at the PIP joint and dorsal proximal phalanx and lumbrical/lateral band release. Degree change of extension was calculated using arctan function with height change of the distal aspect of the proximal phalanx, and the length of the proximal phalanx. We used Student T-test to determine significant decrease in the extension of the phalanges. Extension of all fingers decreased slightly when the extensor tendon were severed at the PIP joint with release of the lateral bands/lumbricals (8deg+/−2deg). After this release, the finger no longer extended. Slight loss of extension was not statistically significant (p >.05) between group 1 and group 2. Groups 1 and 2 were significantly different compared to group 3. In summary, distal extensor tendon transection and release of lateral bands/lumbricals resulted in little change in force and degree of finger extension. The distal insertion of the extensor, released when exposing the PIP joint dorsally, may not need to be repaired to the base of the middle phalanx

Introduction. Hand tumors are usually rare and there is not much literature about series of cases. We have studied a series of 110 cases. Hand tumors do consists of both benign and malignant cases. Methods. We studied series of 110 cases at Karnataka Institute of Medical Sciences, Hubli and Mysore Medical College & Research Institute, Mysore. We retrospectively reviewed the records of 110 patients who underwent double ray amputations at our center over few years: few had amputations of the fourth and fifth rays and others amputation of the second and third rays. Mean age at surgery was 34 years (range, 10–45 years), and minimum follow up was 64 months (mean, 98 months; range, 64–136 months). Some patients had high-grade soft tissue sarcomas of the hand, synovial sarcomas, malignant peripheral nerve sheath tumors, and undifferentiated sarcoma. No patients had detectable metastases at surgery. Results. All patients were completely disease-free at latest follow up. One patient was alive with lung metastases detected 32 months after surgery. No patients developed local tumor recurrence. Functional assessment showed a mean Musculoskeletal Tumor Society score of 24 (range, 19–28) and mean grip strength 24% of the contra lateral side (range, 17%–35%). Conclusions. The majority of osseous tumors of the hand are benign. The surgeon who evaluates and treats osseous tumors of the hand has to be familiar with limb anatomy, tumor biology, various presentations of the tumors and the range of treatment possibilities and their limitations. Lesions in the hand more often present earlier in their course than those at other sites, just because they are more likely to superficial and easily noticed. Ganglion cyst is the most frequently encountered comprising 50–70% of benign tumors of hand. Enchondroma was the next common benign bone tumour followed by osteoid osteoma, osteoblastoma, aneurismal bone cyst, giant cell tumor, epidermoid cyst, and osteochondroma. Although malignant neoplasms in the hand that arise from tissues other than the skin are very rare, the hand may be the site of distant breast, lung, kidney, esophagus, or colon adenocarcinoma metastases, most of which have a predilection for the distal phalanges. Malignant tumours of the hand are rare, although there remain many instances in which marginal excisions are performed for unsuspected malignant hand lesions. Suboptimal biopsy incisions and inadvertent contamination during these excisions may result in larger resections or amputations being necessary to ensure complete removal of the tumour with negative margins

Summary Statement. An alternative way to assess three dimensional skin motion artefacts of kinematic models is presented and applied to a novel kinematic foot model. Largest skin motion is measured in the tarsal region. Introduction. Motion capture systems are being used in daily clinical practise for gait analysis. Last decade several kinematic foot models have been presented to gain more insight in joint movement in various foot pathologies. No method is known to directly measure bone movement in a clinical setting. Current golden standard is based on measurement of motion of skin markers and translation to joint kinematics. Rigid body assumptions and skin motion artefacts can seriously influence the outcome of this approach and rigorous validation is required before clinical application is feasible. Validation of kinematic models is currently done via comparison with bone pin studies. However, these studies can only assess major bones in a highly invasive way; another problem is the non-synchronous measurement of skin markers and bone pins. Recently the Glasgow Maastricht kinematic foot model, which comprises all 26 foot segments, has been presented. To validate the model we propose a novel non-invasive method for the assessment of skin motion artefact, involving loaded CT data. Patients & Methods. 25 subjects (healthy and pathological feet) have undertaken CT scans. These CT-scans have been obtained in 1 unloaded and 3 varying loading conditions. CT-slices are 3D reconstructed and segmented. The principal axes of the segmented bones were derived from the surface points of the bones. These principal axes are used to compute bone orientation. Subsequently, coordinate systems of bones in the different loading conditions were matched. Markers were translated and rotated to orientations of their corresponding bones. Maximal distance between markers is calculated per subject to asses the influence of skin motion. Results. Preliminary results of 9 subjects show largest positional differences for markers associated with the cuneiform lateralis (5.7 ± 3.2 mm) and cuneiform intermedium (7.7 ± 3.7 mm). Smallest positional differences are found on the hallux proximalis (0.9 ± 0.34mm). Spatial resolution is too small to accurately calculate orientation of smaller bones, therefor distal phalanges 2–5 are not taken into account in the analysis. Discussion/Conclusion. Skin motion is a major cause of inaccuracy in gait analysis. This is the first study presenting an automated non-invasive method to calculate the 3D orientation of skin markers with respect to the coordinate system of the corresponding bone(s). Largest skin motion is measured in the tarsal region. Future work will be in calculation of the effect of skin motion in the accuracy of joint angle calculation

Objectives

To determine the pattern of mutations of the WISP3 gene in clinically identified progressive pseudorheumatoid dysplasia (PPD) in an Indian population.

When performing the Scandinavian Total Ankle Replacement (STAR), the positioning of the talar component and the selection of mobile-bearing thickness are critical. A biomechanical experiment was undertaken to establish the effects of these variables on the range of movement (ROM) of the ankle.

Six cadaver ankles containing a specially-modified STAR prosthesis were subjected to ROM determination, under weight-bearing conditions, while monitoring the strain in the peri-ankle ligaments. Each specimen was tested with the talar component positions in neutral, as well as 3 and 6 mm of anterior and posterior displacement. The sequence was repeated with an anatomical bearing thickness, as well as at 2 mm reduced and increased thicknesses. The movement limits were defined as 10% strain in any ligament, bearing lift-off from the talar component or limitations of the hardware.

Both anterior talar component displacement and bearing thickness reduction caused a decrease in plantar flexion, which was associated with bearing lift-off. With increased bearing thickness, posterior displacement of the talar component decreased plantar flexion, whereas anterior displacement decreased dorsiflexion.