The Netherlands has a world-leading position in potato breeding. This thesis analyses the factors... more The Netherlands has a world-leading position in potato breeding. This thesis analyses the factors that have influenced the development of the potato breeding industry in the Netherlands. The research focuses on the period from 1888, when the first crossings were carried out by small breeders, until the present. During that period of time a full potato breeding industry has developed. By means of literature research and interviews with various representatives from the potato breeding sector, the required data was collected to analyse the development of the Dutch potato breeding industry. After the introduction and establishment of the potato in Europe at the end of the sixteenth century, it became clear in the nineteenth century that the crop suffers from degeneration. This created a great need for improvement of quality in varieties and seed potatoes. Although The Netherlands is not the first to start with quality improvement, it is efficient in implementing it, especially due to the close collaboration between all parties involved in the potato chain. There is a simultaneous and mutually influencing development in the relationship between the government and the potato breeding industry. The involvement of and support by the government leads to an expansion of research, institutional infrastructure and legislation. The variety trials testing value for cultivation and use, lead to the introduction of the List of Variety in 1924. Advising, coaching and encouraging breeders is combined in a committee from 1938 onwards. The breeding research expands as a result of this support, but also due to the (free) provision of starting material to practice-based and scientific research. The institutional infrastructure of research and variety breeding, supported by the government, peaks in the 1970s. From then on as a result of policy changes, the government increasingly withdraws from practice-based research and the commercial breeding companies take over. From 1888 especially small breeders are active for the first 50 years. After the introduction of the Breeders' Decree in 1941 and its successor, the Seeds and Planting Act, in 1967 there is a strong development of breeding by companies. This is supported by the exclusive property rights (the monopoly) given to the breeder for his varieties to generate income through royalties. Continuously, even in the twenty-first century, new potato breeding companies arise. A unique collaboration between the commercial breeding companies and the small breeders functions to date, as a form of participatory breeding. A large number of factors determine the strategy of breeding. In one respect, it is 'crop driven', an important factor to maintain the level of production, leading to a continuous flow of new varieties. Breeding strategies are primarily influenced by the many diseases in the potato, but also by developments in cultivation, breeding techniques and markets. On the other hand it is 'export driven', which is a powerful engine in the development of the seed potato sector. The conclusion is that three elements have been the most important in the development of a strong potato breeding sector: the broad cooperation, the design of the institutional infrastructure and the remuneration of the breeding work through plant breeders' rights legislation. The result is an ever-renewing diverse variety package. Currently, the potato breeding industry, with some 15 companies and 150 small breeders, is fully developed and well-organized, with a leading position in the world. Due to the increasing investments in breeding technologies, the relationships in cooperating within an initially broad and open platform are changing to a more closed corporate culture. In addition to joining forces for efficiency and market expansion, it will also be a challenge to maintain the broad diversity in the breeding sector and to keep the smaller companies involved.
Your article is protected by copyright and all rights are held exclusively by Springer Science +B... more Your article is protected by copyright and all rights are held exclusively by Springer Science +Business Media Dordrecht and International Society for Plant Pathology. This e-offprint is for personal use only and shall not be selfarchived in electronic repositories. If you wish to self-archive your article, please use the accepted manuscript version for posting on your own website. You may further deposit the accepted manuscript version in any repository, provided it is only made publicly available 12 months after official publication or later and provided acknowledgement is given to the original source of publication and a link is inserted to the published article on Springer's website. The link must be accompanied by the following text: "The final publication is available at link.springer.com".
As part of the development of a total temporomandibular joint prosthesis, a prosthesis articulati... more As part of the development of a total temporomandibular joint prosthesis, a prosthesis articulation was designed. The articulation consists of a spherical head (ball) of the mandibular part, rotating against an enveloping ultra-high-molecular-weight polyethylene (UHMWPE) disc with a flat cranial side, which slides along the opposing skull part. The aim of this study was to determine the in vitro wear rate of the articulation, and to predict the in vivo wear rate from the results. Based on a disc thickness of 5 mm and a ball diameter of 8 mm, the stresses within the disc were calculated by means of a finite element computer model. The wear rate of the ball-disc articulation was determined by in vitro wear tests, with a stainless-steel ball rotating against a UHMWPE disc in a serum-based lubricant. Eight discs were tested for seven million cycles each. The in vitro wear rate of the disc-skull part articulation was calculated from the test results of the ball-disc articulation. The maximum Von Mises' stress was less than the yield strength of UHMWPE and, therefore, was sufficiently low. The in vitro wear rate of the ball-disc articulation was 0.47 mm3 per million cycles. The in vivo expected total wear rate is 0.65 mm3 per year, corresponding with a yearly decrease of disc thickness of 0.0094 mm. Although it is difficult to judge whether this wear rate is sufficiently low, because the influence of UHMWPE wear particles in the TMJ region is unknown, both the expected wear rate and the decrease of thickness appear to be acceptable.
Fitting a temporomandibular joint (TMJ) prosthesis to the skull by using stock prostheses seems t... more Fitting a temporomandibular joint (TMJ) prosthesis to the skull by using stock prostheses seems to be an appropriate method. However, fitting the skull with one stock part requires many differently shaped parts. Therefore, we fitted the skull with two connected stock parts. The aim of the study was to test whether it is possible to achieve a close fit to the skull with this design, with a maximum of 10 different parts. The articular eminence was fitted with a gully-shaped fitting member, which was rotationally connected to a basic part that fitted to the lateral side of the TMJ. The relevant dimensions of 20 dry skulls were measured and the results were used to derive the optimal dimensions of the prosthesis parts. Prototypes were subsequently fabricated. The fit of the prototypes was tested by measuring the maximum gap between fitting member and skull. All skulls could be fit with a set of four different basic parts and three different fitting members. The average maximum gap between fitting member and skull was 0.20 mm (range 0.11-0.43 mm). It was concluded that a close fit to the skull can be achieved with two connected stock parts and with a total number of seven parts.
To optimize intraoperative neuromonitoring during extreme lateral interbody fusion (XLIF) by addi... more To optimize intraoperative neuromonitoring during extreme lateral interbody fusion (XLIF) by adding transcranial electrical stimulation with motor evoked potential (TESMEP) to previously described monitoring using spontaneous EMG (sEMG) and peripheral stimulation (triggered EMG: tEMG). Twenty-three patients with degenerative lumbar scoliosis had XLIF procedures and were monitored using sEMG, tEMG and TESMEP. Spontaneous and triggered muscle activity, and the MEP of 5 ipsilateral leg muscles, 2 contralateral leg muscles and 1 arm muscle were monitored. During XLIF surgery decreased MEP amplitudes were measured in 9 patients and in 6 patients sEMG was documented. In 4 patients, both events were described. In 30 % of the cases (n = 7), the MEP amplitude decreased immediately after breaking of the table and even before skin incision. After reduction of the table break, the MEP amplitudes recovered to baseline. In two patients, the MEP amplitude deteriorated during distraction of the psoas with the retractor, while no events were reported using sEMG and tEMG. Repositioning of the retractor led to recovery of the MEP. Monitoring the complete nervous system during an XLIF procedure is found to be helpful since nerve roots, lumbar plexus as well as the intradural neural structures may be at risk. TESMEP has additional value to sEMG and tEMG during XLIF procedure: (1) it informed about otherwise unnoticed events, and (2) it confirmed and added information to events measured using sEMG.
Objective: To determine the effects of fluvastatin on lipids, mood and fibrinolysis in dyslipidae... more Objective: To determine the effects of fluvastatin on lipids, mood and fibrinolysis in dyslipidaemic patients with type 2 diabetes mellitus.
The PUCA II pump is a minimally invasive intra-arterial left ventricular assist device that can b... more The PUCA II pump is a minimally invasive intra-arterial left ventricular assist device that can be used as an alternative for the intra-aortic balloon pump (IABP). In this study, we assessed the cardiac unloading and organ perfusion capacities of both PUCA II and IABP in an in vitro set up, consisting of a heart simulator and a silicone arterial tree, mimicking anatomical geometry and flow distribution. The IABP was positioned in the descending aorta, while the PUCA II was tested both in 'trans-aortic' and 'abdominal' positions. All devices were driven by the same Arrow AutoCat IABP driver at different pump rates. Apart from flow, arterial pressure and pulse pressure, we also calculated haemodynamic indices for myocardial oxygen supply and demand. The 'abdominal' PUCA II assist and the IABP both provide mild unloading of the heart, and a limited improvement of arterial pressure and flow. The 'trans-aortic' PUCA II assist greatly enhances flow and pres...
International journal of oral and maxillofacial surgery, 2002
Patients with a severely degenerated temporomandibular joint (TMJ) may benefit from an alloplasti... more Patients with a severely degenerated temporomandibular joint (TMJ) may benefit from an alloplastic TMJ replacement. The aim of the study was to develop a safe and properly functioning TMJ prosthesis. The design was based on imitation of anterior condylar translation by an inferiorly located centre of rotation, unrestricted mandibular movements by a double articulation, correct fit to the skull by a self-adjusting skull part consisting of two connected parts, and stable fixation by bone screws that are rigidly connected to the prosthesis parts. The prosthesis consists of a titanium skull part with ceramic inlay, a titanium mandibular part with a ceramic spherical head, and an intervening polyethylene disc. Titanium-alloy bone screws are used for fixation. All parts are available in a number of different shapes. In vitro laboratory and in vivo animal tests showed a low wear rate, the possibility of a close fit to the skull, a stable fixation, sufficient mechanical strength, appropriat...
International journal of oral and maxillofacial surgery, 2000
As part of the pre-clinical testing process of a newly developed temporomandibular joint (TMJ) pr... more As part of the pre-clinical testing process of a newly developed temporomandibular joint (TMJ) prosthesis, animal experiments were performed. In 14 sheep, the right TMJ was replaced by the developed TMJ prosthesis. The prosthesis consisted of a skull part, a mandibular part and an intervening polyethylene disc. In the first series (6 sheep), three designs were tested, differing in the applied metal (stainless steel or titanium) and in the fitting method of the skull part (a fitting member or bone cement). The sheep were sacrificed after 8-16 weeks. In the second series (8 sheep), the preferred titanium fitting member design was applied, and the sheep were sacrificed after 2-10 weeks. One sheep was excluded because no correct position of the prosthesis parts could be achieved. At sacrifice, the removal torque of the screws was measured, and the surrounding tissues were harvested for histologic examination. The sheep recovered well and functioned until the end of the scheduled sacrifi...
Background: In Western Europe, low back pain has the greatest burden of all diseases. When back p... more Background: In Western Europe, low back pain has the greatest burden of all diseases. When back pain persists, different medical specialists are involved and a lack of consensus exists among these specialists for medical decision-making in Chronic Low Back Pain (CLBP).
With the use of conventional C-arm fluoroscopy for hand surgery, suboptimal positioning of implan... more With the use of conventional C-arm fluoroscopy for hand surgery, suboptimal positioning of implants, K-wires, insufficient reconstructions and joint incongruities frequently remain unrevealed We prospectively compared the performance of the surgeon interpreted from conventional methods (2D fluoroscopy and direct visual and physical inspection) versus 3D imaging as well as the occurrence of revision surgeries based on post-op radiological findings. Twenty-four intraoperative findings based on 2D fluoroscopy and findings on direct visual and physical inspections were compared with intraoperatively acquired 3D-RX scans by means of a questionnaire. Moreover, record was kept of revision surgery (minimal three months follow up) for all patients treated with the aid of 3D-RX. A clear difference in findings was observed between the performance based on fluoroscopy and direct visual and physical inspection and that based on intraoperative 3D-RX for hand surgery (p < 0.05). Post-operative radiological examinations revealed that none of the 56 patients treated with the aid of 3D-RX needed revision surgery. Intraoperative 3D-RX provides information for the hand surgeon that is additional to the information acquired with conventional fluoroscopy. Intraoperative 3D-RX provides well defined images of the positioning of osteosynthesis material, of the spatial orientation of carpals, and of reconstruction of the wrist joint.
A modern way of voice rehabilitation after total laryngectomy includes the use of shunt valves an... more A modern way of voice rehabilitation after total laryngectomy includes the use of shunt valves and tracheostoma valves. Problems of fixation to the surrounding tissue are a major drawback in the use of the shunt valve, heat and moisture exchange (HME) filters and, especially, the tracheostoma valve. To solve these problems different tissue connectors were developed. The main objective was to test the feasibility of these prototypes in a new animal model. Here we discuss the results, problems and complications of the selected Saanen goat model. In this prospective laboratory study, 19 healthy adult female Saanen goats (Capra hircus) were used and observed post-surgically for 12 weeks. Selection criteria such as comparable anatomy to humans and easy handling were used for animal model development. Also a literature search using the Medline and the ISI Web of Science databases was performed. The anatomy of the Saanen goat was investigated in a separate postmortem study. Surgery consisted of a laryngotracheal separation and implantation of a tracheo-oesophageal and tracheostoma tissue connector with fibrin tissue glue. Postoperative care consisted of frequent stoma care, monitoring appetite, weight, vital signs and administration of antibiotics, analgesics and mucolytic agents. All animals survived the surgical procedure. However, postoperative care was extensive, labour intensive and was accompanied by several complications. Eleven animals died spontaneously before the end of the experiment. The tracheostoma tissue connector caused signs of local infection in all cases. There was no evidence of infection around the tracheo-oesophageal tissue connector in 18 cases. It was concluded that the use of goats in this tracheostoma model was associated with major complications and should, therefore, only be used for short-term experiments with intensive care. Additional research is needed to see if clinical application of the tissue connectors is possible in the future.
Increased leakage and easier folding of breast implants with a supple, thin wall and a soft, semi... more Increased leakage and easier folding of breast implants with a supple, thin wall and a soft, semiliquid filler gel resulted in the production of thickerwalled silicone implants with a firmer, high cohesive filler material, since the early 1990s. 1 The anatomic contour was re-introduced and the surface was produced in a textured fashion to prevent capsular contraction. 2 -5 The Style 410 w breast implant (McGhan, Arklow, Ireland) was marketed on this basis since 1993. 6,7 Recently, a softer, less cohesive gel filler has been introduced under the name of Style 410 Soft Touch w (McGhan, Arklow, Ireland) for it's allegedly more natural feel to the breast. There is no difference in anatomic shape, volume, and thickness of shell or texturing of the surface between these types of implants. The difference in softness to touch should be significant to justify using the new Soft Touch implant rather than the original Style 410 implant. Because we had difficulty in noticing this difference, we set out this study.
Fitting a temporomandibular joint (TMJ) prosthesis to the skull by using stock prostheses seems t... more Fitting a temporomandibular joint (TMJ) prosthesis to the skull by using stock prostheses seems to be an appropriate method. However, fitting the skull with one stock part requires many differently shaped parts. Therefore, we fitted the skull with two connected stock parts. The aim of the study was to test whether it is possible to achieve a close fit to the skull with this design, with a maximum of 10 different parts. The articular eminence was fitted with a gully-shaped fitting member, which was rotationally connected to a basic part that fitted to the lateral side of the TMJ. The relevant dimensions of 20 dry skulls were measured and the results were used to derive the optimal dimensions of the prosthesis parts. Prototypes were subsequently fabricated. The fit of the prototypes was tested by measuring the maximum gap between fitting member and skull. All skulls could be fit with a set of four different basic parts and three different fitting members. The average maximum gap between fitting member and skull was 0.20 mm (range 0.11-0.43 mm). It was concluded that a close fit to the skull can be achieved with two connected stock parts and with a total number of seven parts.
The Netherlands has a world-leading position in potato breeding. This thesis analyses the factors... more The Netherlands has a world-leading position in potato breeding. This thesis analyses the factors that have influenced the development of the potato breeding industry in the Netherlands. The research focuses on the period from 1888, when the first crossings were carried out by small breeders, until the present. During that period of time a full potato breeding industry has developed. By means of literature research and interviews with various representatives from the potato breeding sector, the required data was collected to analyse the development of the Dutch potato breeding industry. After the introduction and establishment of the potato in Europe at the end of the sixteenth century, it became clear in the nineteenth century that the crop suffers from degeneration. This created a great need for improvement of quality in varieties and seed potatoes. Although The Netherlands is not the first to start with quality improvement, it is efficient in implementing it, especially due to the close collaboration between all parties involved in the potato chain. There is a simultaneous and mutually influencing development in the relationship between the government and the potato breeding industry. The involvement of and support by the government leads to an expansion of research, institutional infrastructure and legislation. The variety trials testing value for cultivation and use, lead to the introduction of the List of Variety in 1924. Advising, coaching and encouraging breeders is combined in a committee from 1938 onwards. The breeding research expands as a result of this support, but also due to the (free) provision of starting material to practice-based and scientific research. The institutional infrastructure of research and variety breeding, supported by the government, peaks in the 1970s. From then on as a result of policy changes, the government increasingly withdraws from practice-based research and the commercial breeding companies take over. From 1888 especially small breeders are active for the first 50 years. After the introduction of the Breeders' Decree in 1941 and its successor, the Seeds and Planting Act, in 1967 there is a strong development of breeding by companies. This is supported by the exclusive property rights (the monopoly) given to the breeder for his varieties to generate income through royalties. Continuously, even in the twenty-first century, new potato breeding companies arise. A unique collaboration between the commercial breeding companies and the small breeders functions to date, as a form of participatory breeding. A large number of factors determine the strategy of breeding. In one respect, it is 'crop driven', an important factor to maintain the level of production, leading to a continuous flow of new varieties. Breeding strategies are primarily influenced by the many diseases in the potato, but also by developments in cultivation, breeding techniques and markets. On the other hand it is 'export driven', which is a powerful engine in the development of the seed potato sector. The conclusion is that three elements have been the most important in the development of a strong potato breeding sector: the broad cooperation, the design of the institutional infrastructure and the remuneration of the breeding work through plant breeders' rights legislation. The result is an ever-renewing diverse variety package. Currently, the potato breeding industry, with some 15 companies and 150 small breeders, is fully developed and well-organized, with a leading position in the world. Due to the increasing investments in breeding technologies, the relationships in cooperating within an initially broad and open platform are changing to a more closed corporate culture. In addition to joining forces for efficiency and market expansion, it will also be a challenge to maintain the broad diversity in the breeding sector and to keep the smaller companies involved.
Your article is protected by copyright and all rights are held exclusively by Springer Science +B... more Your article is protected by copyright and all rights are held exclusively by Springer Science +Business Media Dordrecht and International Society for Plant Pathology. This e-offprint is for personal use only and shall not be selfarchived in electronic repositories. If you wish to self-archive your article, please use the accepted manuscript version for posting on your own website. You may further deposit the accepted manuscript version in any repository, provided it is only made publicly available 12 months after official publication or later and provided acknowledgement is given to the original source of publication and a link is inserted to the published article on Springer's website. The link must be accompanied by the following text: "The final publication is available at link.springer.com".
As part of the development of a total temporomandibular joint prosthesis, a prosthesis articulati... more As part of the development of a total temporomandibular joint prosthesis, a prosthesis articulation was designed. The articulation consists of a spherical head (ball) of the mandibular part, rotating against an enveloping ultra-high-molecular-weight polyethylene (UHMWPE) disc with a flat cranial side, which slides along the opposing skull part. The aim of this study was to determine the in vitro wear rate of the articulation, and to predict the in vivo wear rate from the results. Based on a disc thickness of 5 mm and a ball diameter of 8 mm, the stresses within the disc were calculated by means of a finite element computer model. The wear rate of the ball-disc articulation was determined by in vitro wear tests, with a stainless-steel ball rotating against a UHMWPE disc in a serum-based lubricant. Eight discs were tested for seven million cycles each. The in vitro wear rate of the disc-skull part articulation was calculated from the test results of the ball-disc articulation. The maximum Von Mises' stress was less than the yield strength of UHMWPE and, therefore, was sufficiently low. The in vitro wear rate of the ball-disc articulation was 0.47 mm3 per million cycles. The in vivo expected total wear rate is 0.65 mm3 per year, corresponding with a yearly decrease of disc thickness of 0.0094 mm. Although it is difficult to judge whether this wear rate is sufficiently low, because the influence of UHMWPE wear particles in the TMJ region is unknown, both the expected wear rate and the decrease of thickness appear to be acceptable.
Fitting a temporomandibular joint (TMJ) prosthesis to the skull by using stock prostheses seems t... more Fitting a temporomandibular joint (TMJ) prosthesis to the skull by using stock prostheses seems to be an appropriate method. However, fitting the skull with one stock part requires many differently shaped parts. Therefore, we fitted the skull with two connected stock parts. The aim of the study was to test whether it is possible to achieve a close fit to the skull with this design, with a maximum of 10 different parts. The articular eminence was fitted with a gully-shaped fitting member, which was rotationally connected to a basic part that fitted to the lateral side of the TMJ. The relevant dimensions of 20 dry skulls were measured and the results were used to derive the optimal dimensions of the prosthesis parts. Prototypes were subsequently fabricated. The fit of the prototypes was tested by measuring the maximum gap between fitting member and skull. All skulls could be fit with a set of four different basic parts and three different fitting members. The average maximum gap between fitting member and skull was 0.20 mm (range 0.11-0.43 mm). It was concluded that a close fit to the skull can be achieved with two connected stock parts and with a total number of seven parts.
To optimize intraoperative neuromonitoring during extreme lateral interbody fusion (XLIF) by addi... more To optimize intraoperative neuromonitoring during extreme lateral interbody fusion (XLIF) by adding transcranial electrical stimulation with motor evoked potential (TESMEP) to previously described monitoring using spontaneous EMG (sEMG) and peripheral stimulation (triggered EMG: tEMG). Twenty-three patients with degenerative lumbar scoliosis had XLIF procedures and were monitored using sEMG, tEMG and TESMEP. Spontaneous and triggered muscle activity, and the MEP of 5 ipsilateral leg muscles, 2 contralateral leg muscles and 1 arm muscle were monitored. During XLIF surgery decreased MEP amplitudes were measured in 9 patients and in 6 patients sEMG was documented. In 4 patients, both events were described. In 30 % of the cases (n = 7), the MEP amplitude decreased immediately after breaking of the table and even before skin incision. After reduction of the table break, the MEP amplitudes recovered to baseline. In two patients, the MEP amplitude deteriorated during distraction of the psoas with the retractor, while no events were reported using sEMG and tEMG. Repositioning of the retractor led to recovery of the MEP. Monitoring the complete nervous system during an XLIF procedure is found to be helpful since nerve roots, lumbar plexus as well as the intradural neural structures may be at risk. TESMEP has additional value to sEMG and tEMG during XLIF procedure: (1) it informed about otherwise unnoticed events, and (2) it confirmed and added information to events measured using sEMG.
Objective: To determine the effects of fluvastatin on lipids, mood and fibrinolysis in dyslipidae... more Objective: To determine the effects of fluvastatin on lipids, mood and fibrinolysis in dyslipidaemic patients with type 2 diabetes mellitus.
The PUCA II pump is a minimally invasive intra-arterial left ventricular assist device that can b... more The PUCA II pump is a minimally invasive intra-arterial left ventricular assist device that can be used as an alternative for the intra-aortic balloon pump (IABP). In this study, we assessed the cardiac unloading and organ perfusion capacities of both PUCA II and IABP in an in vitro set up, consisting of a heart simulator and a silicone arterial tree, mimicking anatomical geometry and flow distribution. The IABP was positioned in the descending aorta, while the PUCA II was tested both in 'trans-aortic' and 'abdominal' positions. All devices were driven by the same Arrow AutoCat IABP driver at different pump rates. Apart from flow, arterial pressure and pulse pressure, we also calculated haemodynamic indices for myocardial oxygen supply and demand. The 'abdominal' PUCA II assist and the IABP both provide mild unloading of the heart, and a limited improvement of arterial pressure and flow. The 'trans-aortic' PUCA II assist greatly enhances flow and pres...
International journal of oral and maxillofacial surgery, 2002
Patients with a severely degenerated temporomandibular joint (TMJ) may benefit from an alloplasti... more Patients with a severely degenerated temporomandibular joint (TMJ) may benefit from an alloplastic TMJ replacement. The aim of the study was to develop a safe and properly functioning TMJ prosthesis. The design was based on imitation of anterior condylar translation by an inferiorly located centre of rotation, unrestricted mandibular movements by a double articulation, correct fit to the skull by a self-adjusting skull part consisting of two connected parts, and stable fixation by bone screws that are rigidly connected to the prosthesis parts. The prosthesis consists of a titanium skull part with ceramic inlay, a titanium mandibular part with a ceramic spherical head, and an intervening polyethylene disc. Titanium-alloy bone screws are used for fixation. All parts are available in a number of different shapes. In vitro laboratory and in vivo animal tests showed a low wear rate, the possibility of a close fit to the skull, a stable fixation, sufficient mechanical strength, appropriat...
International journal of oral and maxillofacial surgery, 2000
As part of the pre-clinical testing process of a newly developed temporomandibular joint (TMJ) pr... more As part of the pre-clinical testing process of a newly developed temporomandibular joint (TMJ) prosthesis, animal experiments were performed. In 14 sheep, the right TMJ was replaced by the developed TMJ prosthesis. The prosthesis consisted of a skull part, a mandibular part and an intervening polyethylene disc. In the first series (6 sheep), three designs were tested, differing in the applied metal (stainless steel or titanium) and in the fitting method of the skull part (a fitting member or bone cement). The sheep were sacrificed after 8-16 weeks. In the second series (8 sheep), the preferred titanium fitting member design was applied, and the sheep were sacrificed after 2-10 weeks. One sheep was excluded because no correct position of the prosthesis parts could be achieved. At sacrifice, the removal torque of the screws was measured, and the surrounding tissues were harvested for histologic examination. The sheep recovered well and functioned until the end of the scheduled sacrifi...
Background: In Western Europe, low back pain has the greatest burden of all diseases. When back p... more Background: In Western Europe, low back pain has the greatest burden of all diseases. When back pain persists, different medical specialists are involved and a lack of consensus exists among these specialists for medical decision-making in Chronic Low Back Pain (CLBP).
With the use of conventional C-arm fluoroscopy for hand surgery, suboptimal positioning of implan... more With the use of conventional C-arm fluoroscopy for hand surgery, suboptimal positioning of implants, K-wires, insufficient reconstructions and joint incongruities frequently remain unrevealed We prospectively compared the performance of the surgeon interpreted from conventional methods (2D fluoroscopy and direct visual and physical inspection) versus 3D imaging as well as the occurrence of revision surgeries based on post-op radiological findings. Twenty-four intraoperative findings based on 2D fluoroscopy and findings on direct visual and physical inspections were compared with intraoperatively acquired 3D-RX scans by means of a questionnaire. Moreover, record was kept of revision surgery (minimal three months follow up) for all patients treated with the aid of 3D-RX. A clear difference in findings was observed between the performance based on fluoroscopy and direct visual and physical inspection and that based on intraoperative 3D-RX for hand surgery (p < 0.05). Post-operative radiological examinations revealed that none of the 56 patients treated with the aid of 3D-RX needed revision surgery. Intraoperative 3D-RX provides information for the hand surgeon that is additional to the information acquired with conventional fluoroscopy. Intraoperative 3D-RX provides well defined images of the positioning of osteosynthesis material, of the spatial orientation of carpals, and of reconstruction of the wrist joint.
A modern way of voice rehabilitation after total laryngectomy includes the use of shunt valves an... more A modern way of voice rehabilitation after total laryngectomy includes the use of shunt valves and tracheostoma valves. Problems of fixation to the surrounding tissue are a major drawback in the use of the shunt valve, heat and moisture exchange (HME) filters and, especially, the tracheostoma valve. To solve these problems different tissue connectors were developed. The main objective was to test the feasibility of these prototypes in a new animal model. Here we discuss the results, problems and complications of the selected Saanen goat model. In this prospective laboratory study, 19 healthy adult female Saanen goats (Capra hircus) were used and observed post-surgically for 12 weeks. Selection criteria such as comparable anatomy to humans and easy handling were used for animal model development. Also a literature search using the Medline and the ISI Web of Science databases was performed. The anatomy of the Saanen goat was investigated in a separate postmortem study. Surgery consisted of a laryngotracheal separation and implantation of a tracheo-oesophageal and tracheostoma tissue connector with fibrin tissue glue. Postoperative care consisted of frequent stoma care, monitoring appetite, weight, vital signs and administration of antibiotics, analgesics and mucolytic agents. All animals survived the surgical procedure. However, postoperative care was extensive, labour intensive and was accompanied by several complications. Eleven animals died spontaneously before the end of the experiment. The tracheostoma tissue connector caused signs of local infection in all cases. There was no evidence of infection around the tracheo-oesophageal tissue connector in 18 cases. It was concluded that the use of goats in this tracheostoma model was associated with major complications and should, therefore, only be used for short-term experiments with intensive care. Additional research is needed to see if clinical application of the tissue connectors is possible in the future.
Increased leakage and easier folding of breast implants with a supple, thin wall and a soft, semi... more Increased leakage and easier folding of breast implants with a supple, thin wall and a soft, semiliquid filler gel resulted in the production of thickerwalled silicone implants with a firmer, high cohesive filler material, since the early 1990s. 1 The anatomic contour was re-introduced and the surface was produced in a textured fashion to prevent capsular contraction. 2 -5 The Style 410 w breast implant (McGhan, Arklow, Ireland) was marketed on this basis since 1993. 6,7 Recently, a softer, less cohesive gel filler has been introduced under the name of Style 410 Soft Touch w (McGhan, Arklow, Ireland) for it's allegedly more natural feel to the breast. There is no difference in anatomic shape, volume, and thickness of shell or texturing of the surface between these types of implants. The difference in softness to touch should be significant to justify using the new Soft Touch implant rather than the original Style 410 implant. Because we had difficulty in noticing this difference, we set out this study.
Fitting a temporomandibular joint (TMJ) prosthesis to the skull by using stock prostheses seems t... more Fitting a temporomandibular joint (TMJ) prosthesis to the skull by using stock prostheses seems to be an appropriate method. However, fitting the skull with one stock part requires many differently shaped parts. Therefore, we fitted the skull with two connected stock parts. The aim of the study was to test whether it is possible to achieve a close fit to the skull with this design, with a maximum of 10 different parts. The articular eminence was fitted with a gully-shaped fitting member, which was rotationally connected to a basic part that fitted to the lateral side of the TMJ. The relevant dimensions of 20 dry skulls were measured and the results were used to derive the optimal dimensions of the prosthesis parts. Prototypes were subsequently fabricated. The fit of the prototypes was tested by measuring the maximum gap between fitting member and skull. All skulls could be fit with a set of four different basic parts and three different fitting members. The average maximum gap between fitting member and skull was 0.20 mm (range 0.11-0.43 mm). It was concluded that a close fit to the skull can be achieved with two connected stock parts and with a total number of seven parts.
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