PubMed Health⌕ Search

Biomedical subjects

P M Werker

Publications and source records attributed to P M Werker.

At least 19 recordsLinked to original sources
PubMed2001

Gracilis muscle neosphincter for treating urinary incontinence.

The purpose of this study was to test the anatomical and functional feasibility of using a gracilis muscle free flap to create a urinary sphincter. Anatomical studies were performed in 12 human cadavers and short-term (n = 7) and long-term (n = 8) functional studies were performed in dogs. In the short-term functional studies, the left gracilis muscle was transferred into the pelvis and wrapped around the urethra and the right gracilis muscle was wrapped around a stent. A cuff electrode was placed on the muscle's nerve pedicle and used to stimulate the neosphincter while peak pressure, fatigue rate, and perfusion measurements were performed. In the long-term functional studies, intramuscular electrodes were inserted into the neosphincter to stimulate the flap. The flaps were wrapped around the urethra and dogs were followed for 16 weeks, during which time urodynamic measurements were performed. Our anatomical studies demonstrated that the gracilis muscle free flap could be transferred into the pelvis to create a urinary neosphincter. Our short-term functional study demonstrated that gracilis muscle free-flap function and perfusion were not compromised by transfer. In our long-term functional study, all neosphincters provided bladder outlet resistance pressures consistent with continence. Our anatomical, short-term, and long-term functional studies indicate that a gracilis muscle free-flap neosphincter is an effective procedure for treating urinary incontinence.

Animals↗
PubMed2001

The long-term durability of plication of the anterior rectus sheath assessed by ultrasonography.

The purpose of this study was to assess the long-term durability of a standard vertical plication of the anterior rectus sheath. For this purpose, 70 women who had undergone this procedure as part of an abdominoplasty were sent a questionnaire, their records were studied, and they were invited back to the clinic for an examination using ultrasound. A total of 63 patients returned the questionnaire, and 40 were willing to attend a follow-up consultation and ultrasound investigation. The presence of rectus diastasis was assessed by ultrasound (a real time scanner with a 7.5-MHz linear probe). The study showed that after a follow-up of 32 to 109 months (mean, 64 months), standard plication of the abdominal wall with absorbable material led to residual or recurrent diastasis in 40 percent of the patients. It also confirmed that vertical plication only is not enough to improve the waistline and may eventually lead to epigastric bulging.

Abdomen↗
PubMed2001

Complications of abdominoplasty in 86 patients.

A total of 101 consecutive abdominoplasty patients were reviewed retrospectively. Of these, 14 male (mean age at time of operation, 34.3 years; range, 23 to 53 years) and 72 female (mean age at time of operation, 38.9 years; range, 19 to 64 years) patients had adequate documentation for inclusion in this study. Complications were recorded as either wound complications (wound infection, partial wound dehiscence, seroma, hematoma, and skin edge necrosis) or complications after surgery (deep vein thrombosis, pulmonary emboli, ileus, sensibility disorder of the skin of the thighs, and death). The complications were subsequently correlated for sex, race, the patient's age at surgery, body mass index before surgery, and the seniority of the surgeon. Nine male patients (64.3 percent) and 11 female patients (15.3 percent) had wound complications. Almost 10 percent of our patients sustained an injury to the lateral cutaneous nerve of the thigh. Male patients should be informed about their possible higher risk of complications, and special attention must be given by the surgeon to the prevention of such complications.Moreover, specific attention must be given to the preservation of the lateral cutaneous nerves of the thigh in both male and female patients undergoing abdominoplasties.

Abdomen↗
PubMed2000

[Fifty years of plastic surgery in the Netherlands. IX. Reconstructive surgery illustrated by breast reconstruction].

The earliest reports on reconstructive surgery are more than two thousand years old. However, the most significant developments took place in the past four decades. At the beginning of the 21st century we are able to perform reconstructions with a moderate functional and good cosmetic result and limited donor site morbidity. The reconstructive options regarding the mammary region include application of mammary implantation only, and techniques in which autologous tissues are applied, with or without implantations. Autologous tissue is used in transposition of the M. latissimus dorsi, in application of the myocutaneous flap of the M. rectus abdominis ('transverse rectus abdominis myocutaneous flap' (TRAM flap)), which is refined in the 'deep inferior epigastric artery perforator' (DIEP) flap procedure.

Female↗
PubMed2000

[Custom-made gold plate prosthesis in the upper eyelid in patients with facial paralysis: improved eyelid closure with less effects on other eye complaints].

OBJECTIVE: To obtain insight into the results of treatment of lagophthalmos by gold weight implantation in the upper eyelid. DESIGN: Retrospective. METHODS: The records of all 37 patients treated in the Netherlands (1986-1998) were reviewed. All traceable patients (n = 33) were sent a questionnaire and invited for clinical evaluation of the treated eye (n = 28). RESULTS: The average follow-up was 44 months (range: 3-150). Twenty-seven patients (82%) reported improved eye closure. After 6 weeks 13 patients (48%) had no eye complaints (dry eye, epiphora, conjunctivitis). At the clinical evaluation 10 patients (36%) had no such complaints. Nine patients (27%) had to undergo a reintervention because of malposition or spontaneous extrusion of the gold weight. It was removed in 4 of them. Upon closure the average residual palpebral aperture was 1.17 mm (range: 0-5) in the patients with gold weight in situ and 6.00 mm (5-10) in the patients in whom the implant had been removed. CONCLUSION: A better eye closure was obtained in 82% of the patients, while eye complaints resolved in 36% of them.

Adolescent↗
PubMed2000

Improving the preservation of isolated rat skeletal muscles stored for 16 hours at 4 degrees C.

BACKGROUND: Limiting factors for long-term cold preservation of isolated skeletal muscles are increased intracellular calcium levels, the occurrence of hypercontraction, and the overproduction of oxygen free radicals. In the present study, we investigated whether muscle preservation during cold storage could be improved by additives that can protect against such processes or by oxygen supply. METHODS: The soleus (SOL) and a strip of the cutaneus trunci muscle (CT) from the rat were isolated and stored for 16 hr at 4 degrees C in Bretschneider's Histidine Tryptophane Ketoglutarate (HTK) and subsequently acclimatized in Krebs-Henseleit solution for 90 min at room temperature. The protective effects of 2,3-butanedione monoxime (BDM; reduces intracellular calcium release and inhibits fiber contraction) and of the following antioxidants were investigated: N-tert-butyl-alpha-phenylnitrone (PBN), trolox, desferal, and deferione. The antioxidants and BDM were added to both HTK and Krebs-Henseleit solution. Dose-response curves were made for each of the additives (n> or =4 for each dose). To evaluate the effect of oxygen supply, HTK was aerated with 95% O2/5% CO2. Muscle function (P0), energy metabolism (ATP), and cytoarchitecture were analyzed. The measured values were compared with those of fresh unstored muscles (% of control) and with those of muscles stored in HTK without any additive (multivariate analysis of variance, P<0.05). RESULTS: We found a significant protection of the contractile function (P0) of both muscles after the addition of 1 mM of trolox (SOL: 46% of control; CT: 53%) and after the addition of 3 mM or 0.3 mM of deferione to the SOL and CT, respectively (P0 for both muscles: 55%), whereas no protection was found with PBN (0.03-1 mM) and Desferal (0.001-1 mM). The addition of BDM (10 or 30 mM) resulted in the highest increase of P0 (84% and 60% for the SOL and CT, respectively). The combinations BDM-trolox and BDM-deferione did not further improve the preservation of the SOL function, but P0 values (88% and 91% of control, respectively) were not different from those found for control muscles. Oxygenation of HTK was only beneficial for the SOL (P0: 83%). The improved preservation of muscle function was accompanied by a reduction of the twitch threshold current, increased by storage, suggesting a protective effect of the intervention on the preservation of the muscle cell membrane integrity. Biochemical and histological data corresponded well with the functional data. CONCLUSIONS: The results showed that the addition of BDM and antioxidants (trolox and deferione) to the bathing solutions improved the preservation of the function, metabolism, and cytoarchitecture of isolated skeletal muscles after cold storage for 16 hr.

Animals↗
PubMed2000

Effect of vascular freezing on the histopathology of dissected small vessels in the rat: vascular freezing does induce intimal hyperplasia in arteries and veins.

Intimal hyperplasia is the primary response of a vessel wall after injury. It may be the single most significant factor affecting long-term patency. The purpose of this study was to find out whether freeze injury, inflicted on rat microvessels, would be followed by intimal hyperplasia. Toward this aim, we exposed the superficial femoral vessels in the rat. On one side they were frozen using liquid nitrogen spray. The other side was dissected as the control. Vessel segments, harvested immediately and after 1, 2, 3, and 5 months, were studied light microscopically for the occurrence and content of intimal hyperplasia. In the arteries a considerable intimal hyperplasia was found within a 4-week interval, persisting for at least 5 months, as a result of the freeze injury. In the veins, the intimal hyperplasia was much less marked but was nevertheless demonstrable. These findings are not in agreement with earlier studies, in which freezing of injured rat microarteries with liquid nitrogen spray was followed by complete regeneration of the vessel wall, without intimal hyperplasia taking place. The factors contributing to these differences are discussed. It is concluded that freezing of a vessel wall is followed by intimal hyperplasia, which is part of the normal healing process.

Animals↗
PubMed2000

Retrospective outcome analysis of staged flexor tendon reconstruction.

Forty staged flexor tendon reconstructions were done in 38 patients between 1991 and 1997. Results were assessed by clinical examination and questionnaire. At follow-up (mean, 35 months) a tenolysis had already been done in 12 cases. In the long fingers there was a significant difference between total active motion (187 degrees ) and total passive motion (237 degrees ). There was also a significant difference between active (24 degrees ) and passive (58 degrees ) IP motion in the thumbs. The mean power grip was 82%, pinch grip 74% and key grip 63% of the contralateral hand. None of the ten FPL reconstructions could be graded as excellent; four were good, using the criteria of Buck-Gramcko et al. (1976). Twenty-eight of the FDP reconstructions had excellent or good results. These results were better than the subjective scores given by the patients, 24 of whom complained of functional problems in daily life at follow-up.

Adolescent↗
PubMed2000

Sequential segmental neuromuscular stimulation reduces fatigue and improves perfusion in dynamic graciloplasty.

Dynamic graciloplasty is used as a treatment modality for total urinary incontinence caused by a paralyzed sphincter. A problem with this application is undesirable fatigue of the muscle caused by continuous electrical stimulation. Therefore, the neosphincter must be trained via a rigorous regimen to transform it from a fatigue-prone state to a fatigue-resistant state. To avoid or shorten this training period, the application of sequential segmental neuromuscular stimulation (SSNS) was examined. This form of stimulation proved previously to be highly effective in acutely reducing fatigue caused by electrical stimulation. The contractile function and perfusion of gracilis muscles employed as neosphincters were compared between conventional, single-channel, continuous stimulation, and multichannel sequential stimulation in 8 dogs. The sequentially stimulated neosphincter proved to have an endurance 2.9 times longer (as measured by halftime to fatigue) than continuous stimulation and a better blood perfusion during stimulation (both of which were significant changes, p < 0.05). Clinically, this will not antiquate training of the muscle, but SSNS could reduce the need for long and rigorous training protocols, making dynamic graciloplasty more attractive as a method of treating urinary or fecal incontinence.

Animals↗
PubMed2000

Use of the rectus abdominis muscle for abdominal stoma sphincter construction: an anatomical feasibility study.

Permanent fecal abdominal stomas significantly decrease quality of life. Previous attempts to create continent stomas by using dynamic myoplasty procedures have resulted in disappointing outcomes, primarily owing to denervation atrophy of the muscle flap that was used in the creation of the sphincter and because of muscle fatigue resulting from continuous electrical stimulation that is received by the flap to force contraction. On the basis of these problems, we designed two separate studies: an anatomical study addressing flap denervation and a functional study addressing muscle fatigue. The present study addresses the first topic and was designed to develop a rectus abdominis muscle flap into a sphincter that was anatomically situated to create a stoma while preserving as much innervation as possible. In 24 rectus abdominis muscles of human cadavers, the neurovascular anatomy was defined, then the anatomical feasibility of two different muscle flap configurations was considered. The flaps investigated were the peninsula flap and island flap designs, with both using the most caudal segment of the rectus abdominis muscle in construction of the sphincter. Neither flap design required the killing of a nerve for stoma sphincter creation, resulting in minimal muscle denervation. The conclusion of our comparison was that the above, in conjunction with other features of the island flap design, such as muscle overlap after sphincter formation and abdominal wall positioning of the sphincter, made the island flap design better suited to stoma sphincter construction.

Abdomen↗
PubMed2000

Sequential segmental neuromuscular stimulation: an effective approach to enhance fatigue resistance.

Electrical stimulation of skeletal muscle flaps is used clinically in applications that require contraction of muscle and force generation at the recipient site, for example, to assist a failing myocardium (cardiomyoplasty) or to reestablish urinary or fecal continence as a neo-sphincter (dynamic graciloplasty). A major problem in these applications (muscle fatigue) results from the nonphysiologic manner in which most of the fibers within the muscle are recruited in a single burst-like contraction. To circumvent this problem, current protocols call for the muscle to be put through a rigorous training regimen to transform it from a fatigue-prone to a fatigue-resistant state. This process takes several weeks during which, aside from becoming fatigue-resistant, the muscle loses power and contraction speed. This study tested the feasibility of electrically stimulating a muscle flap in a more physiologic way; namely, by stimulating different anatomical parts of the muscle sequentially rather than the entire muscle all at once. Sequential segmental neuromuscular stimulation (SSNS) allows parts of the muscle to rest while other parts are contracting. In a paired designed study in dogs (n = 7), the effects of SSNS on muscle fatigability and muscle blood perfusion in gracilis muscles were compared with conventional stimulation: SSNS on one side and whole muscle stimulation on the other. In SSNS, electrodes were implanted in the muscles in such a way that four separate segments of each muscle could be stimulated separately. Then, each segment was stimulated so that part of the muscle was always contracted while part was always resting. This type of stimulation permitted sequential yet continuous force generation. Muscles in both groups maintained an equal amount of continuous force. In SSNS muscles, separate segments were stimulated so that the duty cycle for any one segment was 25, 50, 75, or 100 percent, thus varying the amount of work and rest that any segment experienced at any one time. With duty cycles of 25, 50, and 75 percent, SSNS produced significantly (p < 0.01) enhanced resistance to fatigue. In addition, muscle perfusion was significantly (p < 0.01) increased in these sequentially stimulated muscles compared with the controls receiving whole muscle stimulation. It was concluded that SSNS reduces muscle fatigue and enhances muscle blood flow during stimulation. These findings suggest that using SSNS in clinical myoplasty procedures could obviate the need for prolonged training protocols and minimize problems associated with muscle training.

Animals↗
PubMed1999

[Free muscle transplantation after complex fractures of the lower leg and ankle: results from 32 patients].

OBJECTIVE: To describe the results of free vascularized muscle transfer for treatment of complications of severe open fractures of the distal tibia and ankle region. DESIGN: Retrospective. METHODS: In 1994-1998, 32 patients underwent free muscle transfer for soft tissue reconstruction after high energy injury to the distal tibia and ankle region. In six patients reconstruction took place within one week after the injury (group 1); 13 patients underwent free muscle transfer in combination with (re)osteosynthesis and cancellous bone grafting for treatment of infected (defect) pseudarthrosis (group 2); chronic posttraumatic osteitis existed for an average of 12 years in six patients (group 3); in seven patients the indication was determined by unstable scar tissue, cosmetic reasons, or as preparation for corrective osteotomy (group 4). RESULTS: Three haematomas and two thrombembolic complications were encountered. Amputation could not be avoided in three patients. Consolidation of the fracture, pseudarthrosis or arthrodesis and/or eradication of infection was accomplished in all remaining 29 patients. An average of 2.2 (range: 0-7) reinterventions were additionally needed in groups 1-3, including reosteosynthesis, sequestrectomy, cancellous bone grafting and/or arthrodesis. CONCLUSION: In case of severe open fracture of the distal tibia and/or ankle region, free vascularized muscle transfer provided cover of the fracture or pseudarthrosis region, thereby improving local vascularisation. This treatment protects the underlying bone, enhances osteogenesis and improves resistance to infection.

Adult↗
PubMed1999

Microcirculatory changes following different temperature washouts in a free flap model.

In spite of the extensive experimental work on vascular washout in free flap surgery, an optimal temperature for the washout solution has not been established. This study was designed to determine the effect of the washout solution temperature on the degree to which the microcirculation is cleared of blood. The cremaster muscle flap in the rat was used, in which the microcirculation can be directly viewed and the presence of blood and perfusion parameters within various vessels can be measured during and after washout. Washout was started with a single, high-pressure infusion and continued at 130 mmHg for 15 minutes. The temperature of the washout solution was either 2-3, 20-22, or 35 degrees C. In all three groups, washout cleared the microcirculation almost completely within the first minute. However, we observed that a cold or room temperature washout cleared the microcirculation more completely than a warm washout did. The temperature of the washout solution did not effect post washout capillary perfusion and/or arterial diameters.

Animals↗
PubMed1999

Contractile properties of rat skeletal muscles following storage at 4 degrees C.

The purpose of this study was to assess the potential of preservation solutions for protecting skeletal muscle function during storage at 4 degrees C. The soleus and the cutaneus trunci (CT) from the rat were stored for 2, 8 or 16 h at 4 degrees C in University of Wisconsin solution (UW), HTK-Bretschneider solution (HTK) or Krebs-Henseleit solution (KH). After storage, muscles were stimulated electrically to analyse the isometric contractile properties, such as the maximum tetanic tension (P(0)). Histological analysis was also performed. In separate experiments, the effect of the diffusion distance on muscle preservation was studied by bisecting the soleus. After 8 h of storage in UW or HTK, the contractile properties of the CT were similar to those of the control, whereas those of the soleus were reduced (P(0) values of 16% and 69% of control in UW and HTK respectively). At 16 h, the contractile properties of the CT (P(O) 28%) were again better preserved than those of the soleus (P(0) 9%). Muscle function deteriorated most after storage in KH (P(0) at 16 h: soleus, 3%; CT, 17%). The bisected soleus was equally well preserved as the CT (P(O) of bisected soleus at 8 h in UW and HTK: 86%). The functional data corresponded well with the histological data, which showed increasing muscle fibre derangement with increasing storage time. For both muscles and all solutions, the threshold stimulus current increased with increasing storage time (control, 0.1 mA; 16 h, 1.2 mA) and was strongly correlated with the deterioration in contractile properties. It is concluded that, at 4 degrees C, muscle is preserved better in UW and HTK (intracellular-like solutions) than in KH (extracellular-like solution). The soleus and CT were best protected in HTK. The diffusion distance is a critical factor for successful preservation of muscle function at 4 degrees C. The reduced function after 16 h of storage at 4 degrees C was caused by hypercontraction and necrosis of about 25% of the muscle fibres, and by deterioration of the electrical component of excitation-contraction coupling of the remaining fibres.

Animals↗
PubMed1999

Three parameters optimizing closed-loop control in sequential segmental neuromuscular stimulation.

In conventional dynamic myoplasties, the force generation is poorly controlled. This causes unnecessary fatigue of the transposed/transplanted electrically stimulated muscles and causes damage to the involved tissues. We introduced sequential segmental neuromuscular stimulation (SSNS) to reduce muscle fatigue by allowing part of the muscle to rest periodically while the other parts work. Despite this improvement, we hypothesize that fatigue could be further reduced in some applications of dynamic myoplasty if the muscles were made to contract according to need. The first necessary step is to gain appropriate control over the contractile activity of the dynamic myoplasty. Therefore, closed-loop control was tested on a sequentially stimulated neosphincter to strive for the best possible control over the amount of generated pressure. A selection of parameters was validated for optimizing control. We concluded that the frequency of corrections, the threshold for corrections, and the transition time are meaningful parameters in the controlling algorithm of the closed-loop control in a sequentially stimulated myoplasty.

Algorithms↗
PubMed1998

Muscular urinary sphincter: electrically stimulated myoplasty for functional sphincter reconstruction.

PURPOSE: To reconstruct an electrically stimulated muscular urinary sphincter (MUS) using a tailored gracilis muscle free flap with intact nerve. MATERIALS AND METHODS: Unilateral surgically tailored gracilis muscle free flaps were transferred into the pelvis in eight dogs, leaving the obturator nerve intact. The muscle's pedicle vessels were anastomosed to the inferior epigastric artery and vein in the pelvis and the muscle was wrapped around the bladder neck. Electrodes were inserted into the MUS and connected to a programmable pulse generator. After 8 weeks of training the MUS, the pulse generator was programmed to be "on" for 4 hours and "off' for 15 minutes in a continuous cycle. Urodynamic studies were performed periodically, and at the end of the experiment the MUS and proximal urethra were harvested for histology. Three control dogs had sham operations. RESULTS: All MUS's functioned well following the procedure. Histology of the MUS/urethra complex showed no evidence of stricture. Except for one dog, all urethras were easily catheterized. CONCLUSIONS: This electrically stimulated innervated free-flap MUS technique effectively increases bladder outlet resistance without producing urethral obstruction.

Animals↗