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P Messmer

Publications and source records attributed to P Messmer.

At least 37 records · Page 2Linked to original sources
PubMed2001

[Computer assisted surgery, 2001 development and prospects. Results of a congress at Reisensburg Castle, 23-24 November 2000]].

The progress in computer assisted surgery (CAS) is influenced by new technologies in imaging as well as by the input of the users. At present, CAS procedures are established in dorsal spine instrumentation, prosthetics and long bone surgery. Present status and future of CAS was a topic of an expert meeting at the Reisensburg castle. Imaging will speed up in the future using multi-detector techniques. C-arm navigation will gain more information using the 3D technology intraoperatively. CT based navigation procedures are standard in spine and will be established in pelvic surgery. CAS in robotics at the moment means the use of robot-assistance. A new concept is the modality-based navigated surgery, which can be used at various skeletal locations. Visualization of patient data will improve using 3D semi-transparencies with real time update. In the future it will be mandatory to find algorithms to fuse the different possibilities and techniques. A new concept of surgical training is necessary to teach CAS procedures. Therefore discussion must go on to improve these systems.

Forecasting↗
PubMed2001

[Navigation systems for image-guided therapy: A review].

Navigation systems for image-guided therapy: A review. Navigation is visually interactive targeting based on the simultaneous display of instrument position and of the corresponding two- or three-dimensional image data sets. In this way it unifies anatomic information and therapeutic action. Medical navigation systems (MNS) can simulate realtime image guidance and thereby reduce radiation exposure as well as provide the full range of digital image processing during an intervention. Navigation is based on the tracking of medical instruments in space and the transformation of image, patient, and instrument coordinates into a common reference system. If the patient coordinate system is used as the common base, the process is called patient-based navigation (PBN). If, however, the imaging modality is present in the interventional suite and its reference system is used, modality-based navigation (MBN) results. MBN does not need pre-interventional registration and inherently provides intra-operative imaging. In neurosurgery MNS's have been well established since years. They are in use for frameless biopsies and for minimizing the access morbidity in deeply situated pathologies. Currently there is a fast expansion of navigation into other surgical disciplines, e.g., orthopaedic surgery. The clinical accuracy of an MNS is hard to determine since an independent method of measurement is mostly not available during surgery. Normally, a deviation of below one up to about 5 mm between the display of the MNS and the actual position of an anatomic structure is reported. So far there have been only very few prospective randomized clinical trials between conventional and navigated interventions.

Forecasting↗
PubMed2000

Surgical navigation based on fluoroscopy--clinical application for computer-assisted distal locking of intramedullary implants.

OBJECTIVE: Fluoroscopy is used to guide surgical instruments during orthopedic procedures. Radiation exposure and lack of spatial information are drawbacks of this method. Improvements are expected when fluoroscopy-based surgical navigation is used for intraoperative guidance, e.g., in computer-assisted distal locking of intramedullary implants. PATIENTS AND METHODS: The method was applied to 42 interlocking procedures during implantation of the short proximal femoral nail in 27 patients with pertrochanteric femoral fractures. Precision of interlocking, exposure time, operating time, and number of personnel required for computer-assisted distal locking were recorded. RESULTS: One misplaced interlocking screw was observed (2.3%), and contact between the drill bit and the nail during drilling was noticed in 8 cases (19%). The average exposure time was 16 seconds (range 4-42 seconds), and the procedure took an average of 43 min (range 20-70 min). The number of persons required for computer-assisted distal locking was reduced from three to one within the course of the study. CONCLUSIONS: Fluoroscopy-based surgical navigation provided precise intraoperative guidance for computer-assisted distal locking with minimal use of fluoroscopy. The complex system and related procedure times may be drawbacks in this application. Clinical studies are underway to define implants and surgical procedures where intraoperative guidance by fluoroscopy-based surgical navigation is beneficial for the patient and/or surgeon.

Computer Simulation↗
PubMed2000

Chronic post-traumatic osteomyelitis of the lower extremity: comparison of magnetic resonance imaging and combined bone scintigraphy/immunoscintigraphy with radiolabelled monoclonal antigranulocyte antibodies.

OBJECTIVE: A retrospective study of the validity of combined bone scintigraphy (BS) and immunoscintigraphy (IS) using (99m)Tc-labelled murine antigranulocyte antibodies (MAB) and magnetic resonance imaging (MRI) in chronic posttraumatic osteomyelitis. DESIGN AND PATIENTS: The results of MRI and combined BS/IS of 19 lesions in 18 patients (13 men, 5 women; mean age 45 years, range 27-65 years) were independently evaluated by two radiologists and one nuclear medicine physician with regard to bone infection activity and extent. The patient group was a highly selective collection of clinical cases: the average number of operations conducted because of relapsing infection was eight (range 2-27), the average time interval between the last surgical intervention and the present study was 6.5 years (range 3 months to 39 years), and from the first operation was 14 years (range 1.5-42 years). Interobserver agreement on MRI was measured by kappa statistics. Sensitivity, specificity, accuracy, positive predictive value (PPV) and negative predictive value (NPV) were calculated for MRI and the nuclear medicine studies. RESULTS: For MRI/nuclear medicine, a sensitivity of 100%/77%, a specificity of 60%/50%, an accuracy of 79%/61%, a PPV of 69%/58% and a NPV of 100%/71% were calculated. Four MR examinations were false positives because of postsurgical granulation tissue. A high degree of interobserver agreement was found on MRI (kappa=0.88). A low-grade infection was missed on two scintigrams, while four were false positive because of ectopic haematopoietic bone marrow, and in one examination the anatomical distortion resulted in an inaccurate assignment of the uptake leading to false positive findings. Image analysis was frequently hindered by susceptibility artefacts due to residual abrasions of metallic implants after removal of orthopaedic devices (15/18 patients); this led to limited assessment in 17% (3/18 patients). CONCLUSION: Acute activity in a chronic osteomyelitis can be excluded with high probability if the MRI findings are negative. In the first postoperative year fibrovascular scar cannot be distinguished accurately from reactivated infection on MRI and scintigraphy may improve the accuracy of diagnosis. MRI is more sensitive in low-grade infection during the later course than combined BS/IS. Scintigraphic errors due to ectopic, peripheral, haematopoietic bone marrow can be corrected by MRI.

Adult↗
PubMed2000

The multifunctional therapy room of the future: image guidance, interdisciplinarity, integration and impact on patient pathways.

With few exceptions the interventional rooms of the present are either imaging suites or sterile operating rooms. Their users are restricted to either percutaneous procedures or to two-staged image-guided surgery without intra-operative imaging control. Since interventional therapy of the future will be minimally invasive and since minimally invasive therapy is essentially image-guided therapy, a new physical place for these activities has to be devised: the multifunctional therapy room of the future integrates sophisticated imaging and image guidance modalities together with advanced surgical and life-support equipment in a sterile environment [1, 2, 3]. Even given a high degree of integration, this will be a complex and costly piece of medical technology. These two factors--complexity and cost-- require interdisciplinary technological and medical collaboration to bring it into existence, distribute its cost and maximize usage and medical benefit. Yet another dimension of multifunctionality will be introduced and a significant impact on the care of vitally threatened patients will be exerted by using this room not only for elective image-guided therapy but also for emergent one-stop diagnosis and treatment. Motivation, technology, implementation strategies and funding of this image-guided, integrated and interdisciplinary therapy room, as well as a comprehensive approach combining emergency care and elective computer-assisted therapy (CAT), are discussed in this paper.

Critical Pathways↗
PubMed2000

A whole-body registration-free navigation system for image-guided surgery and interventional radiology.

RATIONALE AND OBJECTIVES: To develop and test an image-guided navigation system in which the base of reference is taken from the imaging modality, here, a helical CT scanner. METHODS: An optical digitizer together with a calibration device is used to measure the transformation matrix between the digitizer reference system and a CT reference system. During intervention, it tracks radiological and surgical tools with tool references. A specific software visually integrates the current tool position with the corresponding image information. In vitro accuracy tests were performed. RESULTS: With helical CT, freehand positioning accuracy was 1.9 +/- 1.1 mm (mean +/- SD) in vitro (n = 718). CONCLUSIONS: The navigation system developed by the authors appears to be feasible for radiological interventions as well as for minimally invasive surgery. It is not limited to a certain procedure, can be used in every region of the body, and is functional after imaging. Intraprocedural scans can be integrated immediately.

Equipment Design↗
PubMed1998

[Hemorrhagic pseudocysts and pseudoaneurysms in pancreatitis. Diagnosis and therapy].

Acute hemorrhage from pseudocysts and pseudoaneurysms is a threatening complication of chronic pancreatitis. Whilst surgical intervention still has high perioperative mortality (16.8%), transcatheter arterial embolization is becoming more frequently used for suitable cases and appears to have lower mortality (6.1%). We report on six patients treated in our unit. Four of them underwent primary surgical treatment, the other two were treated by embolisation. One of the latter patients subsequently required laparotomy for further treatment. All six patients survived. Comparing the literature covering the periods between 1951 and 1981 and between 1982 and 1996, transcatheter embolisation seems to be valuable in controlling this type of bleeding, thereby reducing mortality.

Adult↗
PubMed1996

[laparoscopic cholecystectomy and acute cholecystitis--feasibility and morbidity].

This quality control study was devised to establish, wether laparoscopic cholecystectomy is recommendable for acute cholecystitis. Of 314 prospectively recorded laparoscopic cholecystectomies 59 were done for histologically proven acute cholecystitis within 3 years. 29 cases (49.2%) were converted to open cholecystectomy due to unsatisfactory exposure and recognition of anatomical structures or haemorrhage. Morbidity with laparoscopic cholecystectomy without conversion was 16.6% (5/30 patients), mortality zero. There were no common bile duct injuries. Our results show that, if the operation is performed by an experienced laparoscopic surgeon or under one's supervision, laparoscopic cholecystectomy for acute cholecystitis is safe. A low threshold for converting to open laparotomy must be observed particularly when anatomical structures are not clearly identified.

Acute Disease↗
PubMed1993

[Perioperative morbidity and mortality in colon resection for colon cancer].

The operative risk of colon resections was evaluated by a retrospective analysis of 231 according patients who were operated on between 1984 and 1988. Mean age of the patients was 70 years with a range from 37 to 91 years. Colonic resection consisted of ileocecal resection in 3 cases, right hemicolectomy in 144 cases, segmental resection of transverse colon in 10 cases, left hemicolectomy in 22 cases, resection of sigmoid colon in 77 cases and 5 times a subtotal colectomy was performed. In two patients (0.9%) an anastomotic leak occurred. Three patients were reoperated on: one due to an anastomotic disruption, two others due to a mechanical small bowel obstruction. Two patients (0.9%) died due to systemic complications without any evidence of anastomotic or wound problems. Thus a low morbidity and mortality of colonic resection is documented in our study. Factors contributing to these results are a standardized bowel preparation, perioperative antibiotics and modern anaesthetic techniques.

Adult↗
PubMed1993

[Cancer of the gastric stump. An independent disease picture? Consequences for follow-up].

In a retrospective study we analysed the clinical course of 13 patients from the St Clara's Hospital who had a gastric-stump cancer between the years of 1975 and 1989 and compared our figures with the literature. Our figures showed the average age of the patient at their first operation for the gastric ulcer was 35 and, at the second operation for gastric cancer the average age was 68.8 patients were male and 5 were female. When the tumour was discovered it was already advanced. 11 patients had a Grade 3 or 4 tumour. Out of our 13 patients, 7 had to undergo a total removal of the gastric remnant. 1 patient underwent a partial gastrectomy and, 3 patients had a gastrostomy or jejunostomy performed. For 2 patients the tumour was seen to be so advanced that no palliative procedure could be undertaken. When this study was undertaken only 1 patient remained alive and this patient had survived 7 years after removal of the gastric remnant. Because the likelihood of cancer occurring in the gastric stump is four times more frequent than expected we recommend that the patient is endoscoped 20 years after the initial operation and then again regularly every 3 to 5 years after this.

Adult↗
PubMed1993

[Femoral neck fracture and femoral head necrosis].

In this study we wanted to demonstrate the relationship between the fracture of the femoral neck and femoral head necrosis. For this purpose we reviewed the new literature, the dates of the ASIF documentation and some cases from the Davos Hospital. Head necrosis appears in all types of fractures and is independent of the implant. We can find femoral head necrosis in all age groups but the risk is higher the younger the patient. The necrosis can develop many years after the accident. There are not enough long-term studies to explain this phenomenon.

Aged↗
PubMed1992

[Perioperative morbidity and mortality of colon resection in colonic carcinoma].

An analysis of the local and systemic perioperative complications is conducted to explore the risk of resection of colon cancer. In a retrospective study we analyzed 231 consecutive patients operated on between 1984 and 1988. The mean age was 70 (37-91) years. The operations consisted in 3 ileocecal resections, 144 right hemicolectomies, 10 resections of the transverse colon, 22 left hemicolectomies, 77 resections of the sigmoid colon and 5 subtotal colonic resections. 2 patients (0.9%) had a clinical leakage of the anastomosis. 3 patients were reoperated: one because of anastomotic leakage and two because of ileus due to small bowel adhesions. 2 patients with uncomplicated local healing died within 30 days after the operation from systemic complications (mortality 0.9%). It is concluded that with standardized preoperative bowel preparation, prophylactic perioperative antibiotics and modern anesthesia, the resection of colon cancer is today possible with minimal perioperative risk.

Adult↗
PubMed1992

[Radiation-sparing intramedullary nailing with a radiolucent drilling system].

The indications for intramedullary fixation of tibial and femoral shaft fractures markedly increased by the introduction of interlocking techniques. Distal interlocking however remains a major problem although a variety of different aiming devices have been proposed. To reduce the radiation exposure both of the surgeon and the patient the AO has produced a radiolucent drive which allows easy aiming and drilling with a minimum of X-ray exposure.

Femoral Fractures↗
PubMed1992

Surgical treatment for cholelithiasis.

In a retrospective study, the results of 1,631 consecutive operations for cholelithiasis were analyzed. With an overall mortality rate of 0.18 percent and a reoperation rate of 1.3 percent, conventional cholecystectomy proved to be a safe method. Mortality proved to be age dependent, with a zero mortality rate for patients less than 60 years of age. Choledochotomy had a 13-fold greater mortality rate than simple cholecystectomy (0.92 versus 0.07 percent). For acute cholecystitis, we observed an unusual zero mortality rate, whereas the mortality rate in chronic cholecystitis was 0.2 percent. All three patients who died had an accompanying cirrhosis of the liver. Morbidity, defined as reoperation during the same period of hospitalization, was mainly the result of retained stones after choledochotomy; endoscopic papillotomy was the treatment of choice. Cholecystectomy remains the "gold standard" in the treatment of cholelithiasis.

Adolescent↗
PubMedDate not supplied

Delayed union of a sacral fracture: percutaneous navigated autologous cancellous bone grafting and screw fixation.

Delayed or non-union of a sacral fracture is a serious clinical condition that may include chronic pain, sitting discomfort, gait disturbances, neurological problems, and inability to work. It is also a difficult reconstruction problem. Late correction of the deformity is technically more demanding than the primary treatment of acute pelvic injuries. Open reduction, internal fixation (ORIF), excision of scar tissue, and bone grafting often in a multi-step approach are considered to be the treatment of choice in delayed unions of the pelvic ring. This procedure implies the risk of neurological and vascular injuries, infection, repeated failure of union, incomplete correction of the deformity, and incomplete pain relief as the most important complications. We report a new approach for minimally invasive treatment of a delayed union of the sacrum without vertical displacement. A patient who suffered a Malgaigne fracture (Tile C1.3) was initially treated with closed reduction and percutaneous screw fixation (CRPF) of the posterior pelvic ring under CT navigation and plating of the anterior pelvic ring. Three months after surgery he presented with increasing hip pain caused by a delayed union of the sacral fracture. The lesion was successfully treated percutaneously in a single step procedure using CT navigation for drilling of the delayed union, autologous bone grafting, and screw fixation.

Bone Screws↗