Residual Bones Research Articles

Lower extremity osseointegration — a review of the current experiences and expectations

Transcutaneous osseointegration for amputees (TOFA), an alternative approach to limb-loss rehabilitation, offers an enhanced quality of life and mobility, overcoming some challenges associated with amputation. This review presents evolution, surgical techniques, patient selection principles, and outcomes associated with TOFA. Notable points include the recognition that press-fit osseointegration techniques and implants achieve the quality of life and mobility improvements with a single surgical episode. Infection remains the most common adverse event, but uncommonly requires additional surgery, and rarely requires implant removal. Press-fit osseointegration has proven suitable for rehabilitating a broad range of patients with pelvic, transfemoral, or transtibial amputation performed to manage trauma, cancer, infection, chronic pain, and deformity. This technigue is safe for patients with vascular disease, diabetes mellitus, short residual bones, and osteoporotic residual bones. This article serves as a central resource for understanding the principles and techniques of osseointegration.

Modular intercalary prosthetic reconstruction for malignant and metastatic tumours of the proximal femur

To illustrate the surgical technique and explore clinical outcomes of the reconstruction for the malignant and metastatic bone tumour of proximal femur with metallic modular intercalary prosthesis. Sixteen patients who underwent modular intercalary prosthetic reconstruction after tumour resection were included from April 2012 and October 2020. Prosthesis and screws parameters, resected bone length and residual bone length, clinical outcomes and survivorship were analyzed. All patients were followed up for an average of 19 months (range 1–74). In our series, 12 patients died of the progression of the primary disease at the final follow-up. The cumulative survivorship since the treatment of proximal femoral metastasis was 78.6% (11 patients) at 6 months and 38.5% (5 patients) at 1 year. The mean MSTS score was 22.25 ± 4.55 among all patients. There were no cases of loosening or breakage of the prostheses, plates or screws, despite the various measurements of prostheses and residual bones. Modular intercalary prosthetic reconstruction was an effective method for malignant tumour of the proximal femur, including the advantages of providing early pain relief, quickly restoring postoperative function, required a short operation time, and preserving the adjacent joints.

Motorized intramedullary lengthening followed by osseointegration for amputees with short residual femurs: An observational cohort study

Context: Some patients seeking transcutaneous osseointegration for amputees (TOFA) have residual bones so short there is concern whether they provide sufficient surface to support full weight. Our strategy was to lengthen these patients' femurs with a motorized intramedullary lengthening nail (MILN) before TOFA. Aims: The aim of this study is to describe 10 transfemoral amputees' experience with MILN before TOFA, focusing on the complications of MILN and TOFA, and also the patients' preoperative and postoperative quality of life (QOL). Settings and Design: A retrospective registry review of all MILN before TOFA surgeries was performed. Subjects and Methods: The patients' operative complications during/following MILN and TOFA were investigated. Furthermore, the patients' mobility (daily prosthesis wear hours, K-level, Timed Up and Go (TUG), and 6 min Walk Test [6MWT]) and QOL survey data (Questionnaire for Persons with a Transfemoral Amputation [QTFA]) were compared at the initial consultation and at the latest follow-up using Fisher's exact test for frequencies, and Student's t-test for means (significance, P < 0.05). Statistical Analysis Used: Fisher's exact test for frequencies, and Student's t-test for means (significance, P < 0.05). Results: Seven patients had one operative complication each: Three regenerate (autograft and plating), two nail malfunctions (nail replacement), one broken linkage cable (acute length correction with autografting and fixation), and one early consolidation (re-osteotomy). All ten patients had TOFA, an average of 12.0 ± 3.9 months after MILN surgery. One patient had debridement for infection (implant retained) and one patient had the implant removed due to infection. Significant mobility improvements were K-level >2 (2/9 = 22% vs. 9/10 = 90%, P =0.006) and TUG <15 s (1/8 = 13% vs. 6/8 = 75% P = 0.041). Wear hours and 6MWT improved but not significantly. All three aspects of QTFA significantly improved: Global (44.8 ± 29.9 vs. 75.9 ± 26.8, P =0.050), mobility (50.3 ± 30.8 vs. 74.8 ± 18.2, P =.033), and problem (38.8 ± 18.6 vs. 15.6 ± 18.3, P = 0.017). Conclusions: MILN before TOFA reliably achieves stable osseointegration for amputees with short residual femurs. Amputee lengthening remains demanding, but patients report significantly improved QOL and demonstrate improved mobility following TOFA. The minimum length of bone necessary to support a full weight-bearing osseointegrated prosthesis remains unknown.

Follow Up Case of Left Knee TKR: Case Review

Poor wound healing following a major lower limb amputation can result in poor rehabilitation outcomes, which can be further worsened if the patient has recurrent falls and stump trauma during the wound healing stage. Direct trauma to the stump can result in bony fractures at the margins of the residual bones, and loose bony fragments may form inside the stump. These bony fragments can hinder the process of stump wound healing and interfere with prosthetic limb use and rehabilitation.

Detection of Atlantic salmon bone residues using machine vision technology

The detection of foreign bodies in the food industry has received considerable research attention in recent years. This study aimed to assess the efficacy of combining machine vision with neural network models for detecting residual bones in Atlantic salmon flesh as well as explore the degree to which image quality affects the performance of object detection models. We first employed region segmentation and various forms of data expansion to obtain 3120 images of Atlantic salmon bone residues and then used the image compression algorithm to obtain data sets with images that differ in quality. Three object detection models (Faster-RCNN + Alexnet, Faster-RCNN + VGG16 and Faster-RCNN + VGG19) were trained based on uncompressed image data sets. The Faster-RCNN + VGG16 model had optimal test performance on the image data set with a compression ratio of 25% (F1-score = 0.87, AP = 0.78). The Faster-RCNN + VGG16 model for images with a compression ratio of 10% did not show any practical value (F1-score = 0.17, AP = 0.04). Therefore, neural network models based on machine vision can robustly detect residual bones in Atlantic salmon flesh from images containing bones. The quality of images used for detection had a significant impact on the detection results, and small target images should be less robust to compression.

Endoscopic intradural subtemporal keyhole approach with neuronavigational assistance: An anatomic study

Objective To evaluate the feasibility of a purely endoscopic intradural approach to the suprasellar, petroclival and ventrolateral brainstem regions through a subtemporal keyhole and to assess the value of neuronavigational assistance in the Kawase approach. Methods Twenty operations through endoscopic intradural subtemporal keyhole approach were performed on 10 cadaveric heads. An intradural Kawase approach and a navigation-assisted intradural Kawase approach were then carried out on a random side of each specimen. Related anatomic structures were observed through endoscopes. Two types of the milled Kawase rhombus ranges and the thicknesses of residual bones were compared. Results Through the keyhole endoscopic technique, anatomic structures in the suprasellar, petroclival and ventrolateral brainstem regions were clearly visualized via an intradural subtemporal route. Most structures in the suprasellar region could be observed in the oculomotor nerve-posterior communicating artery space. Using a frameless navigational device, the mean area of milled Kawase rhombus was larger than that in the intradural Kawase approach (276.8±14.6 mm2vs. 244.8±12.6 mm2,P<0.05), and the thicknesses of residual bones including the superior wall of internal acoustic meatus (1.0±0.2 mm vs. 2.5±0.4 mm), the medial superior wall of cochlear (1.0±0.2 mm vs. 3.0±0.4 mm) and the superior wall of petrous segment of internal carotid artery (1.2±0.2 mm vs. 3.4±0.4 mm) were all thinner than those in the intradural Kawase approach (all P<0.05). Conclusions The endoscopic intradural subtemporal keyhole approach could facilitate excellent observation of the suprasellar, petroclival and ventrolateral brainstem regions with less invasiveness. More anatomic exposure and surgical freedom could be achieved via neuronavigational assistance. Key words: Neuroanatomy; Neuronavigation; Neuroendoscopy; Subtemporal approach; Keyhole; Kawase approach

Improved osseointegration with as-built electron beam melted textured implants and improved peri‑implant bone volume with whole body vibration

Transcutaneous osseointegrated prostheses provide stable connections to the skeleton while eliminating skin lesions experienced with socket prosthetics. Additive manufacturing can create custom textured implants capable of interfacing with amputees’ residual bones. Our objective was to compare osseointegration of textured surface implants made by electron beam melting (EBM), an additive manufacturing process, to machine threaded implants. Whole body vibration was investigated to accelerate osseointegration. Two cohorts of Sprague-Dawley rats received bilateral, titanium implants (EBM vs. threaded) in their tibiae. One cohort comprising five groups vibrated at 45 Hz: 0.0 (control), 0.15, 0.3, 0.6 or 1.2 g was followed for six weeks. Osseointegration was evaluated through torsional testing and bone volume fraction (BV/TV). A second cohort, divided into two groups (control and 0.6 g), was followed for 24 days and evaluated for resonant frequency, bone-implant contact (BIC) and fluorochrome labeling. The EBM textured implants exhibited significantly improved mechanical stability independent of vibration, highlighting the benefits of using EBM to produce custom textured surfaces. Bone formation on and around the EBM textured implants increased compared to machined implants, as seen by BIC and fluorescence. No difference in torque, BIC or fluorescence among vibration levels was detected. BV/TV significantly increased at 0.6 g compared to control for both implant types.

Valorization of Bone Waste of Saudi Arabia by Synthesizing Hydroxyapatite.

At present, hydroxyapatite is being frequently used for diverse biomedical applications as it possesses excellent biocompatibility, osteoconductivity, and non-immunogenic characteristics. The aim of the present work was to recycle bone waste for synthesis of hydroxyapatite nanoparticles to be used as bone extracellular matrix. For this reason, we for the first time utilized bio-waste of cow bones of Albaha city. The residual bones were utilized for the extraction of natural bone precursor hydroxyapatite. A facile scientific technique has been used to synthesize hydroxyapatite nanoparticles through calcinations of wasted cow bones without further supplementation of chemicals/compounds. The obtained hydroxyapatite powder was ascertained using physicochemical techniques such as XRD, SEM, FTIR, and EDX. These analyses clearly show that hydroxyapatite from native cow bone wastes is biologically and physicochemically comparable to standard hydroxyapatite, commonly used for biomedical functions. The cell viability and proliferation over the prepared hydroxyapatite was confirmed with CCk-8 colorimetric assay. The morphology of the cells growing over the nano-hydroxyapatite shows that natural hydroxyapatite promotes cellular attachment and proliferation. Hence, the as-prepared nano-hydroxyapatite can be considered as cost-effective source of bone precursor hydroxyapatite for bone tissue engineering. Taking into account the projected demand for reliable bone implants, the present research work suggested using environment friendly methods to convert waste of Albaha city into nano-hydroxyapatite scaffolds. Therefore, besides being an initial step towards accomplishment of projected demands of bone implants in Saudi Arabia, our study will also help in reducing the environmental burden by recycling of bone wastes of Albaha city.

Endoscopic Intradural Subtemporal Keyhole Approach with Neuronavigational Assistance to the Suprasellar, Petroclival, and Ventrolateral Brainstem Regions: An Anatomic Study

The purposes of this study were to evaluate the feasibility of a purely endoscopic intradural approach to the suprasellar, petroclival, and ventrolateral brainstem regions through a subtemporal keyhole and to assess the value of neuronavigational assistance in the Kawase approach. Twenty endoscopic intradural subtemporal keyhole approaches were performed on 10 cadaveric heads. An intradural Kawase approach and a navigation-assisted intradural Kawase approach were then carried out on a random side of each specimen. Related anatomic structures were observed through 4-mm 0° and 30° endoscopes; data were measured by a frameless navigational device. In addition, 2 types of the milled Kawase rhombus ranges and the thicknesses of the residual bones were compared. This keyhole endoscopic technique clearly visualized the anatomic structures in the suprasellar, petroclival, and ventrolateral brainstem regions via an intradural subtemporal route. Most of the structures in the suprasellar region were observed by the oculomotor nerve-posterior communicating artery space. Using a frameless navigational device, the mean area of the milled Kawase rhombus increased by 32.04 mm2 (P < 0.05), and the thicknesses of the residual bones including the superior wall of the internal acoustic meatus, the medial superior wall of the cochlea, and the superior wall of the petrous segment of the internal carotid artery reduced by 1.55, 2.03, and 2.19 mm on average, respectively (P < 0.05). The endoscopic intradural subtemporal keyhole approach could facilitate excellent observation of the suprasellar, petroclival, and ventrolateral brainstem regions with less invasiveness. More anatomic exposure and surgical freedom could be achieved via neuronavigational assistance with fewer complications.

Local Antibiotic Therapy for Osteomyelitis of a Replanted Hand

Abstract Background: Although systemic antibiotic therapy is recommended for the prevention and treatment of infection, the use of local antibiotic(s) in the setting of osteomyelitis is well established. Treatment consists of debridement and placement of antibiotics that have been added to bone cement. Hand osteomyelitis will fail periodically after treatment with systemic antibiotics. Debridement is difficult because the fine architecture of the hand limits excessive debridement that might be used in other locations. In the current study, we injected antibiotics directly into the infected bone and soft tissue and had a good result. Case Presentation: A 65-year-old man had a traumatic amputation and replantation of his right hand. He lost the majority of the skin coverage of the dorsum of the amputated hand. During treatment, his residual extensor tendons and bones had severe methicillin-resistant coagulase-negative staphylococcal (MRCNS) infection. Daily drainage and systemic antibiotics for five months ...

Maxillary and Cheek Reconstruction with Titanium Mesh and Folded Free Anterolateral Thigh Flap

Background and purpose: Maxillary and cheek reconstruction is one of the most challenging tasks for surgeons. The purpose of this study was to assess the clinical application and therapeutic efficacy of the maxillary and the through and through cheek defects reconstructed with titanium mesh and folded free anterolateral thigh flap. Materials and methods: Between October 2010 and May 2013, 16 patients were treated for maxillary reconstruction with titanium mesh and folded free anterolateral thigh flap at Sun Yat-Sen University Cancer Center. Intra-operatively, the titanium mesh was fixed to the residual bones for the reconstruction of hard-tissue defects after tumor resection; then the anterolateral thigh flap was harvested and folded to repair the through and through cheek defects, serving as the intraoral lining and titanium mesh covering Result: Apart from one total flap loss, 15 of the 16 free ALT flaps survived. All of the patients achieved a satisfactory facial appearance. No major complications or donor site morbidity occurred. Conclusion: Reconstruction of maxillectomy defects and the through and through cheek defects using titanium mesh in combination with folded free anterolateral thigh flap is a feasible and acceptable option.

Bone-patellar tendon-bone allograft reconstruction for peri-patellar tendon sarcomas: case series.

IntroductionReconstruction after wide resection for a sarcoma involving the knee extensor mechanism is challenging even if the tumor is small.Case descriptionWe report on four consecutive peri-patellar tendon sarcomas treated similarly at a single institution. Histological diagnoses were synovial sarcoma (two cases), clear cell sarcoma and extraskeletal Ewing’s sarcoma (one case each). Follow-up periods after surgery were 18–67 months. All cases underwent pre-operative radiotherapy and subsequent surgery. After preoperative radiotherapy and wide resection including the patellar tendon, bone-patellar tendon-bone allograft was fixed to the residual patella and tibial tuberosity with screws and a cable wire. Soft tissue and skin defect over allograft was covered by free antero-lateral thigh flap. Post-operatively, the operated knee was splinted straight for at least 6 weeks, and then range-of-motion exercise was gradually introduced. Except for one case with a proximal tibial stress fracture 5 months post-operatively, no complication was observed. Both bone–bone junctions between allograft and residual bones were united within 1 year after surgery. At the latest clinical follow-up, all the patients had satisfactory functions with Musculoskeletal Tumor Society score of 28–30 out of 30 points and virtually full range of motion.Discussion and evaluationThis case series is the first to report bone-patellar tendon-bone allograft for reconstruction after tumor resection with joint preservation and with satisfactory clinical outcomes.ConclusionsBone-patellar tendon-bone allograft reconstruction with vascularized flap reconstruction is a viable option for peri-patella tendon sarcomas.Electronic supplementary materialThe online version of this article (doi:10.1186/s40064-015-1510-9) contains supplementary material, which is available to authorized users.

Case presentation of two patients using diagonal platform-switched double implants for maxillary single-first-molar replacement as the alternative of a single-tooth implant.

A single-tooth implant restoration is generally performed for maxillary single-first-molar replacement. If the interdental space between the second premolar and the second molar is large enough, a double-implant placement can be performed to avoid creating mesiodistal cantilever and to distribute occlusal loading forces.If there is not adequate space for a double-implant placement to be performed mesiodistally along the crest of the alveolar ridge line, they should be placed along a diagonal line offset lingually to increase the space. This procedure has two primary advantages. First, greater stability is provided by a double-implant placement. Resistance to lateral forces (palatal-buccal) is much stronger than two implants placed along the alveolar crest ridge line. Residual palatal and buccal bone can provide support against occlusal forces, provided that there is adequate residual bone in these regions.If anatomical conditions are favorable, the placement of two diagonal implants in the palatal and buccal residual bones can be a rational procedure.We report on two typical patients. The progress of these patients was followed using computed tomography for 7 and 6 years, respectively.

Clinical and imaging features of Gorham disease:a report of eleven cases and review of literature

Objective To evaluate the clinical and radiological features of Gorham disease. Methods Clinical and radiological features of Gorham disease were retrospectively analyzed by reviewing the eleven cases from our hospital and the cases reported in the domestic literature in the past fifty years. The diagnoses of all these 11 patients were in accordance with the diagnostic criteria established by Wells and Gray et al. All patients had X-ray plain film, four had CT scan and five had MR examination, with one had additional contrast-enhanced MR examination. Results There were 7 males and 4 females, age ranged from 16 to 66 years with a median age of 32 years. There were six cases involving hand, one involving ulnar and radial bones, one involving acetabulum and three involving jaw bones. The main clinical manifestations were pain, swelling, limited activity, and focal muscular atrophy occurred in 7 cases. On X-ray plain films, the affected bone became thin and the cortexes were not smooth and became coarse in 6 cases. Local lucent area was seen in 5 cases and massive bone absorption was seen in 6 cases. The residual bones showed a tapering appearance in 1 case. Pathological fracture occurred in 1 case. On CT scans, the affected bone became thin and the cortexes became coarse in 4 cases. Local lucent area was seen in 1 case. Massive bone absorption was seen in 3 cases. The adjacent muscular atrophy and widened intermuscular fat space occurred in 2 cases (atrophic bone absorption). On MRI, normal signal intensity of bone marrow disappeared and demonstrated low signal on T1WI and high signal on T2WI. The signal could be homogeneous or heterogeneous. There were widespread strip and patchy high signal areas in the soft tissue around the absorption areas in 4 cases, which resembled the edema- like signal. In 1 case, there was irregular widespread soft tissue mass around the absorption areas with heterogeneous high signal on T2WI. The adjacent muscle showed atrophy, and the intermuscular fat space became wide. There were a total of 92 cases reported cases in the literature including our 11 cases. There were 63 males and 29 females. The onset age ranged from 10 to 40 years in 66/92 (72%) cases. The lesion affected one bone in 24 cases, affected two or more bones in 68 cases, out of which 9 cases had single center distribution, 59 cases had multiple centers distribution. Pectoral girdle, pelvis, maxillofacial bones, and hand were the most common sites of involvement in decreasing order. Forty three cases had muscle atrophy and 8 cases had soft tissue mass. Conclusion Gorham disease should be considered when atrophic bone absorption in one bone or continuous bones occurs that does not match clinical symptoms, with soft tissue atrophy but no bone sclerosis or periosteal reaction in the osteolytic areas. Key words: Osteolysis, essential; Tomography,X-ray computed; Magnetic resonance imaging

Effects of age of cattle, turning technology and compost environment on disappearance of bone from mortality compost

As residual bones in mortality compost negatively impact subsequent tillage, two studies were performed. For the first study, windrows of mature cattle or calves were placed on a base of barley straw and covered with beef manure. Windrows were divided into two sections and turned at 3-month intervals. Approximately 5000 kg of finished compost per windrow was passed through a 6 mm trommel screen, with bones collected and weighed. Bone weight was 0.66% of mature cattle compost and 0.38% of calf compost on a dry matter basis, but did not differ after adjustment for weights of compost ingredients. In a subsequent study, four windrows were constructed containing mortalities, straw and beef manure (STATC) or straw, manure and slaughter waste (STATW). Also, straw, beef manure and slaughter waste was added to an 850 L rolling drum composter (DRUMW). Fresh bovine long-bones from calves were collected, weighed and embedded in the compost. Bones were retrieved and weighed when windrows were turned, or with DRUMW, after 8 weeks. Temperatures achieved followed the order STATW > STATC > DRUMW ( p < 0.05). Rate of bone disappearance followed a pattern identical to temperature, with the weight of bones in STATW declining by 53.7% during 7 weeks of composting. For STATC, temperatures were uniform over three composting periods, but bone disappearance was improved ( p < 0.05) when compost dry matter was lower (46%), as compared to 58%. Using a ratio of five parts manure to one part mortalities, results of this study demonstrated that residual bone was <1% of cured cattle compost and may be reduced by maintaining a high compost temperature and moisture content.

Dual energy CT of peripheral arteries: Effect of automatic bone and plaque removal on image quality and grading of stenoses

Purpose To evaluate the effect of automatic bone and plaque removal on image quality and grading of steno-occlusive lesions in patients undergoing dual energy CT angiography (CTA) of lower extremity. Materials and methods Dual energy (DE) runoff CTA was performed in 50 patients using the following parameters: collimation 2 × 32 × 0.6; tube potentials, 80 kV and 140 kV; reconstructed slice thickness 1 mm. 100 mL iomeprol 400 and 50 mL saline were injected at 4 mL/s. Separate datasets were calculated for each of the two tubes and used to generate automatically bone-subtracted images (ABS) as well as bone and plaque subtracted images (ABPS). Residual bone in the ABS dataset was removed manually (=ABS-B dataset). In addition, a weighted average dataset from both dual energy acquisitions resembling a routine 120 kV CT acquisition was used for standard manual bone subtraction (MBS). Operator time for bone removal was measured. Effectiveness of bone subtraction and presence of vessel erosions was assessed by two readers in consensus. Stenosis grading in plaque subtracted and unsubtracted images was assessed and correlated. Results Residual bone fragments (ribs: 46%, patella: 25%, spine: 4%, pelvis: 2%, tibia 2% of patients) were only observed with ABS. The time needed to manually remove these residual bones was 2.1 ± 1.1 min and was significantly lower than the duration of manual bone removal (6.8 ± 2.0 min, p < 0.0001, paired t-test). A total of 1159 arteries were analyzed. Compromising vessel erosions were observed less frequently in the ABS-B dataset (10.6%) than in the MBS dataset (15.2%, p < 0.001, wilcoxon’s signed rank test). A total of 817 steno-occlusive lesions were assessed. While the agreement of grading of steno-occlusive lesions was good at the levels of the aorta and the pelvic arteries ( κ = 0.70 in both, Cohen’s kappa statistics), it was moderate at the level of the thigh arteries ( κ = 0.57) and poor at the level of the calf ( κ = 0.16). Conclusion DE CTA has substantial advantages over conventional CTA. Automatic bone subtraction is more time efficient and reliable. Automatic plaque subtraction for the first time provides a true CTA-luminogram which is easy to interpret and reduces the need for further post-processing. DE CTA provides best results in arteries of the thigh; below the knee, plaque subtraction is less accurate.

Functional reconstruction of maxilla with pedicled buccal fat pad flap, prefabricated titanium mesh and autologous bone grafts

The aim of this study was to evaluate the use of pedicled buccal fat pad flap (PBFPF), prefabricated titanium mesh and autologous bone graft in maxillary reconstruction. Seventeen patients with a unilateral class I–III maxillary defect were involved. Preoperatively, a solid model was manufactured based on virtual maxillectomy and reconstruction of the abnormal maxilla. Intraoperatively, PBFPF was applied to repair the soft-tissue defect, serving as nasal lining and the receiving bed for bone grafts. Titanium mesh was prefabricated on the solid model and then, together with bone grafts from iliac crest, fixed to residual bones to reconstruct the hard-tissue defect. Postoperative aesthetic appearance and function were followed up. No exposure of titanium mesh, leakage or oronasal regurgitation occurred. Of the patients with a class I or II defect 91% (10/11) and of those with a class III defect 50% (3/6) gained a good appearance. Fifteen patients were articulate. Eleven patients received dental rehabilitation and had a normal diet. PBFPF with prefabricated titanium mesh and autologous bone grafts is a reliable option for reconstruction of unilateral maxillary defects of class I and II, but this method alone should be used cautiously in defects of class III and beyond.

Extraction of muscle proteins and gelatine from cod head

A simple method to extract proteins from minced cod head by mild chemical treatment has been developed. The major part of muscle proteins was recovered by successive extraction at room temperature in dilute NaOH (pH 11) and HCl (pH 2–2.6). Gelatine was extracted at acid conditions and elevated temperatures from residual connective tissues and bones. Almost half of the total protein (47.5%) was extracted from muscle and soft tissues, whereas 12% were recovered as gelatine from soft connective tissues and bones. Functional properties of the various gelatine fractions were compared with functional properties of gelatine extracted from cod skin. Gelatine extracted from soft head connective tissues had similar molecular weight, viscosity and gel strength as gelatine from cod skin. The higher temperatures and stronger acidity necessary to extract gelatine from the head bones, resulted in more hydrolyzed gelatine with poor gelling properties, but still viscosities were only moderately lower than the viscosity of gelatine extracted from soft connective tissues.

A quasi-dynamic nonlinear finite element model to investigate prosthetic interface stresses during walking for trans-tibial amputees

To predict the interface pressure between residual limb and prosthetic socket for trans-tibial amputees during walking. A quasi-dynamic finite element model was built based on the actual geometry of residual limb, internal bones and socket liner. To simulate the friction/slip boundary conditions between the skin and liner, automated surface-to-surface contact was used. Besides variable external loads and material inertia, the coupling between the large rigid displacement of knee joint and small elastic deformation of residual limb and prosthetic components were also considered. Interface pressure distribution was found to have the same profile during walking. The high pressures fall over popliteal depression, middle patella tendon, lateral tibia and medial tibia regions. Interface pressure predicted by static or quasi-dynamic analysis had the similar double-peaked waveform shape in stance phase. The consideration of inertial effects and motion of knee joint cause 210% average variation of the area between the pressure curve and the horizontal line of pressure threshold between two cases, even though there is only a small change in the peak pressure. The findings in this paper show that the coupling dynamic effects of inertial loads and knee flexion must be considered to study interface pressure between residual limb and prosthetic socket during walking.

Load transfer mechanics between trans-tibial prosthetic socket and residual limb—dynamic effects

The effects of inertial loads on the interface stresses between trans-tibial residual limb and prosthetic socket were investigated. The motion of the limb and prosthesis was monitored using a Vicon motion analysis system and the ground reaction force was measured by a force platform. Equivalent loads at the knee joint during walking were calculated in two cases with and without consideration of the material inertia. A 3D nonlinear finite element (FE) model based on the actual geometry of residual limb, internal bones and socket liner was developed to study the mechanical interaction between socket and residual limb during walking. To simulate the friction/slip boundary conditions between the skin and liner, automated surface-to-surface contact was used. The prediction results indicated that interface pressure and shear stress had the similar double-peaked waveform shape in stance phase. The average difference in interface stresses between the two cases with and without consideration of inertial forces was 8.4% in stance phase and 20.1% in swing phase. The maximum difference during stance phase is up to 19%. This suggests that it is preferable to consider the material inertia effect in a fully dynamic FE model.