Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 20 de 33
Filter
1.
Opt Express ; 31(9): 14358-14366, 2023 Apr 24.
Article in English | MEDLINE | ID: mdl-37157301

ABSTRACT

An InGaAsSb p-B-n structure has been designed and characterized for zero bias low power detection applications. Devices were grown by molecular beam epitaxy and fabricated into quasi-planar photodiodes with a 2.25 µm cut-off wavelength. Maximum responsivity was measured to be 1.05 A/W at 2.0 µm, achieved at zero bias. D* of 9.4 × 1010 Jones was determined from room temperature spectra of noise power measurements with calculated D* remaining >1 × 1010 Jones up to 380 K. With a view to simple miniaturized detection and measurement of low concentration biomarkers, optical powers down to 40 pW were detected, without temperature stabilization or phase-sensitive detection, indicating the photodiode's potential.

2.
Eur Cell Mater ; 42: 110-121, 2021 08 19.
Article in English | MEDLINE | ID: mdl-34410680

ABSTRACT

Single-plate fixation bridging bone defects provokes nonunion and risks plate-fatigue failure due to under- dimensioned implants. Adding a helical plate to bridge the fracture increases stiffness and balances load sharing. This study compares the stiffness and plate surface strain of different constructs in a transverse contact and gap femoral shaft fracture model. Eight groups of six synthetic femora each were formed: intact femora; intact femora with lateral locking plate; contact and gap transverse shaft osteotomies each with lateral locking plate, lateral locking plate and helical locking plate, and long proximal femoral nail. Constructs underwent non-destructive quasi-static axial and torsional loading. Plate surface strain evaluation was performed under 200 N axial loading. Constructs with both lateral and helical plates demonstrated similar axial and torsional stiffness- independent of the contact or gap situations - being significantly higher compared to lateral plating (p < 0.01). Torsional stiffness of the constructs, with both lateral and helical plates in the gap situation, was significantly higher compared to this situation stabilised by a nail (p < 0.01). Plate surface strain dropped from 0.3 % in the gap situation with a lateral plate to < 0.1 % in this situation with both a lateral and a helical plate. Additional helical plating increases axial and torsional construct stiffness in synthetic bone and seems to provide well-balanced load sharing. Its use should be considered in very demanding situations for gap or defect fractures, where single-plate osteosynthesis provides inadequate stiffness for fracture healing and induces nonunion.


Subject(s)
Femoral Fractures , Fracture Fixation, Internal , Biomechanical Phenomena , Bone Plates , Femoral Fractures/surgery , Fracture Healing , Humans
3.
Foot Ankle Surg ; 24(4): 326-329, 2018 Aug.
Article in English | MEDLINE | ID: mdl-29409241

ABSTRACT

BACKGROUND: Open reduction and internal fixation is the current standard of treatment of displaced distal fibula fractures, whereupon using a lag screw often is impossible because of a multifragmantary fracturezone. This study investigates in what extend polyaxial-locking plating is superior to non-locking constructs in unstable distal fibula fractures. METHODS: Seven pairs of human cadaver fibulae were double osteotomized in standardized fashion with a 5mm gap. This gap simulated an area of comminution, where both main fragments were no longer in direct contact. One fibula of the pair was managed using a 3.5-mm screw in a polyaxial-locking construct and the other fibula in a non-locking construct.


Subject(s)
Ankle Fractures/surgery , Bone Plates , Fibula/surgery , Fracture Fixation, Internal/instrumentation , Fractures, Comminuted/surgery , Ankle Fractures/physiopathology , Biomechanical Phenomena , Bone Screws , Cadaver , Female , Fibula/injuries , Fibula/physiopathology , Fracture Fixation, Internal/methods , Fractures, Comminuted/physiopathology , Humans , Male , Models, Anatomic
4.
Unfallchirurg ; 120(12): 1020-1030, 2017 Dec.
Article in German | MEDLINE | ID: mdl-28819784

ABSTRACT

CLINICAL ISSUE: Injuries of the peroneal tendons are rare and often overlooked. Typical pathologies are tendinitis, tears and dislocation. Accompanying injuries are fractures. They are often associated with instability in the ankle and rearfoot deformities; therefore, these pathologies should be excluded or taken into consideration in the treatment. The clinical examination is crucial for the diagnosis. DIAGNOSTIC WORK-UP: Ultrasound and magnetic resonance imaging (MRI) examinations are very helpful; however, the true extent of the tendon pathology is often first seen during surgery. Bony injuries and deformities are assessed radiographically and by computed tomography (CT). PERFORMANCE: Although conservative treatment is generally used at the beginning of therapy, progression is more likely to occur in the case of tears; therefore, the correct timing for an operative therapy should not be missed. Dislocations are the domain of operative therapy. Acute tendinitis, on the other hand, is usually accessible to conservative therapy if it is not the result of a gross deformity. ACHIEVEMENTS: Rehabilitation after operative treatment is demanding and prolonged especially after operative therapy of peroneal tendon tears. The results to be expected appear promising.


Subject(s)
Ankle Injuries/diagnosis , Muscle, Skeletal/injuries , Tendon Injuries/diagnosis , Algorithms , Ankle Injuries/surgery , Diagnosis, Differential , Fibula/injuries , Fibula/surgery , Follow-Up Studies , Humans , Joint Dislocations/diagnosis , Joint Dislocations/surgery , Postoperative Care/methods , Postoperative Complications/diagnosis , Postoperative Complications/rehabilitation , Suture Techniques , Tendinopathy/diagnosis , Tendinopathy/surgery , Tendon Injuries/surgery , Tomography, X-Ray Computed
5.
Rozhl Chir ; 95(10): 354-358, 2016.
Article in Czech | MEDLINE | ID: mdl-27879140

ABSTRACT

INTRODUCTION: The aim of the study was to evaluate the results of fluorescence angiography for assessing anastomotic perfusion after resection of the sigmoid colon and rectum since its introduction into clinical practice at the authors´ workplace and to evaluate the incidence of necessary resection line repositioning based on the quality of perfusion, and also to record any complications in anastomotic healing. METHOD: Retrospective unicentric analysis of prospectively collected data from patients with resection of the sigmoid colon and rectum with primary anastomosis. The patient set included 50 patients, 27 males and 23 females; the median age was 64.5 years (33-80). Forty-four patients were indicated for resection for cancer of the sigmoid colon or rectum, while 6 patients had a benign disease. Twenty-nine patients underwent total mesorectal excision with coloanal mechanical or hand-sewn anastomosis and 21 underwent resection of the sigmoid colon or upper rectum with mechanical anastomosis. Prior to the construction of the anastomosis, assessment of perfusion of the anastomotic segments by near infrared (NIR) indocyanine green (ICG) fluorescence angiography was performed in all patients. The quality of perfusion of the mesocolon and bowel wall and its impact on moving the resection line and complications of anastomotic healing 30 days postoperatively were all evaluated. RESULTS: Assessment of perfusion using fluorescence angiography was technically successfully performed in all 50 patients. In 5 cases (10%) the resection line had to be moved for signs of poor perfusion of the bowel wall. Postoperatively, healing of the anastomosis was complicated in four patients (8%). Dehiscence was recorded in 3 patients (10.3%) with total mesorectal excision and in 1 patient (4.8%) after resection of the sigmoid colon and upper rectum. CONCLUSION: The presented results indicate that fluorescence angiography may lead to a decrease in the incidence of anastomotic dehiscence after colorectal resections by mapping in detail the perfusion of the anastomosed segments.Key words: fluorescence angiography - indocyanine green - anastomotic leak - colorectal resection.


Subject(s)
Anastomosis, Surgical/methods , Colectomy/methods , Colon, Sigmoid/surgery , Colorectal Neoplasms/surgery , Rectum/surgery , Adult , Aged , Aged, 80 and over , Anastomotic Leak/epidemiology , Colon, Sigmoid/blood supply , Digestive System Surgical Procedures , Female , Fluorescein Angiography , Humans , Male , Mesocolon/blood supply , Middle Aged , Perfusion Imaging , Rectum/blood supply , Retrospective Studies , Surgical Wound Dehiscence/epidemiology
6.
Klin Onkol ; 29(5): 351-357, 2016.
Article in English | MEDLINE | ID: mdl-27739314

ABSTRACT

BACKGROUND: The primary objective of this study was to investigate the impact of high protein oral nutrition support (ONS) on clinical outcomes in patients with colorectal cancer (CRC). The secondary aim was to compare the cost of treatment and length of stay (LoS) for CRC patients taking high protein ONS vs. patients on conventional nutritional support. MATERIALS AND METHODS: The study was conducted on adult patients with CRC undergoing colorectal surgery. Informed consent was obtained before the study. The study group (SG; n = 52) was instructed to take high protein ONS (600 kcal, 40 g protein per day) in addition to a normal diet for at least 10 days before and two weeks after surgery. Data from the comparative group (CG; n = 105) were collected retrospectively. RESULTS: A relative reduction in the frequency of the following complications was observed in SG: wound dehiscence (2.2 times lower), infections (4.3 times lower), anastomosis dehiscence (2.0 times lower), and rehospitalization (1.7 times lower). The mean LoS was shorter in SG (9.4 ± 4.97 vs. CG 12 ± 6.4 days), which resulted in significantly lower treatment costs during hospitalization (SG 479 vs. CG 538 EUR; p = 0.01) and at six months after surgery (SG 4,862 vs. CG 6,456 EUR). CONCLUSION: Pre- and postoperative high protein ONS reduces LoS, treatment costs, postoperative complications, and re-hospitalizations in CRC, regardless of initial nutritional status.Key words: high protein oral nutritional support - colorectal cancer - perioperative care.


Subject(s)
Colorectal Neoplasms/diet therapy , Colorectal Neoplasms/economics , Colorectal Surgery/economics , Colorectal Surgery/rehabilitation , Dietary Proteins/administration & dosage , Hospitalization/economics , Administration, Oral , Adult , Colorectal Neoplasms/surgery , Dietary Supplements , Humans , Length of Stay , Nutritional Support , Retrospective Studies , Treatment Outcome
7.
Phytopathology ; 106(11): 1344-1351, 2016 11.
Article in English | MEDLINE | ID: mdl-27213558

ABSTRACT

Quantitative trait loci (QTL) for barley stripe rust resistance were mapped in recombinant inbred lines (RIL) from a 'Lenetah' × 'Grannelose Zweizeilige' (GZ) cross. GZ is known for a major seedling resistance QTL on chromosome 4H but linked markers suitable for marker-assisted selection have not been developed. This study identified the 4H QTL (log of the likelihood [LOD] = 15.94 at 97.19 centimorgans [cM]), and additional QTL on chromosomes 4H and 6H (LOD = 5.39 at 72.7 cM and 4.24 at 34.46 cM, respectively). A QTL on chromosome 7H (LOD = 2.04 at 81.07 cM) was suggested. All resistance alleles were derived from GZ. Evaluations of adult plant response in Corvallis, OR in 2013 and 2015 provided evidence of QTL at the same positions. However, the minor QTL on 4H was not statistically significant in either location/year, while the 7H QTL was significant in both. The single-nucleotide polymorphism markers flanking the resistance QTL were validated in RIL from a '95SR316A' × GZ cross for their ability to predict seedling resistance. In 95SR316A × GZ, 91 to 92% of RIL with GZ alleles at the major 4H QTL and at least one other were resistant to moderate in reaction. In these populations, at least two QTL were required to transfer the barley stripe rust resistance from GZ.


Subject(s)
Basidiomycota/physiology , Disease Resistance/genetics , Hordeum/genetics , Plant Diseases/immunology , Polymorphism, Single Nucleotide/genetics , Quantitative Trait Loci/genetics , Alleles , Genetic Markers/genetics , Genotyping Techniques , Hordeum/immunology , Hordeum/microbiology , Plant Diseases/microbiology , Seedlings/genetics , Seedlings/immunology , Seedlings/microbiology
8.
Orthop Traumatol Surg Res ; 102(5): 645-9, 2016 09.
Article in English | MEDLINE | ID: mdl-27179630

ABSTRACT

BACKGROUND: In plate osteosynthesis involving the distal fibula, antiglide plating is superior to lateral plating in terms of the biomechanical properties. The goal of this study was to examine whether polyaxial-locking implants confer additional benefits in terms of biomechanical stability. METHODS: Seven pairs of human cadaveric fibulae were subjected to osteotomy in a standardized manner to simulate an uncomplicated Weber B fracture. The generated fractures were managed with a dorsolateral antiglide plate. To this end, one fibula of the pair was subjected to non-locking plating and the other to polyaxial-locking plating. Biomechanical tests included quantification of the primary bending and torsional stiffness. In addition, the number of cycles to failure in cyclic bending loading were determined and compared. Bone mineral density was measured in all specimens. RESULTS: Bone mineral density was comparable in both groups. Primary stability was higher in the polyaxial-locking group under torsional loading, and higher in the non-locking group under bending loading. The differences, however, were not statistically significant. All specimens except for one fixed-angle construct failed the cyclic loading test. The number of cycles to failure did not differ significantly between polyaxial-locking and non-locking fixation. CONCLUSION: In a cadaveric Weber B fracture model, we observed no differences in biomechanical properties between polyaxial-locking and non-locking fixation using an antiglide plate. Based on the biomechanical considerations, no recommendation can be made regarding the choice of the implant. Further biomechanical and clinical studies are required. CLINICAL RELEVANCE: Information on the behavior of polyaxial-locking plates is relevant to surgeons performing internal fixation of distal fibula fractures.


Subject(s)
Bone Plates , Fracture Fixation, Internal/instrumentation , Materials Testing , Aged , Aged, 80 and over , Biomechanical Phenomena , Cadaver , Female , Fibula/injuries , Fibula/surgery , Humans , Male , Prosthesis Design
9.
Clin Biomech (Bristol, Avon) ; 34: 7-11, 2016 05.
Article in English | MEDLINE | ID: mdl-27015031

ABSTRACT

BACKGROUND: Subtle hypermobility of the first tarsometatarsal joint can occur concomitantly with other pathologies and may be difficult to diagnose. Peroneus Longus muscle might influence stability of this joint. Collapse of the medial longitudinal arch is common in flatfoot deformity and the muscle might also play a role in correcting Meary's angle. METHODS: A radiolucent frame was used to simulate weightbearing during CT examination. Eight pairs fresh-frozen lower legs were imaged in neutral position under non-weightbearing (75N), weightbearing (700N) and with 15kg weights hung from Peroneus Longus tendon. Measurements included first metatarsal rotation, intermetatarsal angle, first tarsometatarsal joint subluxation and Meary's angle. FINDINGS: Weightbearing significantly increased Meary's angle and significantly decreased first tarsometatarsal joint subluxation (both P<0.01). Pulling Peroneus Longus tendon significantly increased first metatarsal rotation (P<0.01), significantly decreased the intermetatarsal angle (P<0.01) and increased non-significantly Meary's angle (P=0.52). INTERPRETATION: A considerable effect weightbearing has on the medial longitudinal arch and first tarsometatarsal joint was observed. Pulling Peroneus Longus tendon improved first metatarsal subluxation but increased its rotation. The study calls into question the importance of this tendon in maintaining the medial longitudinal arch and raises concerns about rotational deformity of the first metatarsal following hallux valgus correction without first tarsometatarsal arthrodesis. CLINICAL RELEVANCE: Study outcomes will provide more insight in foot pathology. WHAT IS KNOWN ABOUT THE SUBJECT: Weightbearing affects anatomy of the foot. No reliable information is available concerning the influence of the Peroneus muscle. WHAT THIS STUDY ADDS TO EXISTING KNOWLEDGE: This study investigates the influence of weightbearing and the impact the Peroneus muscle on the anatomy of the foot.


Subject(s)
Foot/physiology , Muscle, Skeletal/physiology , Tarsal Joints/physiology , Aged , Aged, 80 and over , Cadaver , Female , Flatfoot/physiopathology , Foot/diagnostic imaging , Humans , Joint Dislocations/physiopathology , Male , Middle Aged , Muscle, Skeletal/diagnostic imaging , Rotation , Tarsal Joints/diagnostic imaging , Tendons/diagnostic imaging , Tendons/physiology , Tomography, X-Ray Computed , Weight-Bearing
10.
Rozhl Chir ; 94(2): 64-8, 2015 Feb.
Article in Czech | MEDLINE | ID: mdl-25659255

ABSTRACT

INTRODUCTION: First experiences with laparoscopic low anterior resection with transanal mesorectal excision in patients with low and mid rectal cancer are referred. METHODS: During a 9 month period (between October 2013 and May 2014), 17 laparoscopically assisted rectal resections with transanal total mesorectal excision, hand-sewn colo-anal anastomosis and protective ileostomy were performed at two institutions (CHK FN Brno, CHO KOC Nový Jicín). There were 11 males and 6 females, with a mean age 68 years (range 49-81 years) in our cohort. The tumor was located 30-80mm from the anal verge (median 60 mm). RESULTS: A negative distal resection margin was achieved in all patients. The circumferential resection margin was positive in two cases. The TME quality was described as complete in 8 cases and nearly complete in 9 cases. Mean operative time was 280 min (range 212-375 min) with no intra-operative complications. Anastomotic leakage was observed in two patients (12%). Median length of postoperative hospital stay was 9 days with a range of 6-30 days, in case of anastomotic and wound complications. CONCLUSION: According to our first experience we evaluated this method as feasible and safe with satisfactory pathological outcomes. We cannot recommend exact indications yet. It is assumed that the transanal approach for total mesorectal excision should be indicated in obese patients with a narrow pelvis and voluminous prostate.Key words: total mesorectal excision transanal minimally invasive surgery.


Subject(s)
Colectomy/methods , Natural Orifice Endoscopic Surgery/methods , Rectal Neoplasms/surgery , Aged , Aged, 80 and over , Anal Canal , Female , Humans , Male , Middle Aged
11.
Rozhl Chir ; 93(12): 564-7, 2014 Dec.
Article in Czech | MEDLINE | ID: mdl-25472560

ABSTRACT

Transanal total mesorectal excision performed using equipment for transanal minimally invasive surgery is an innovative surgical technique introduced to facilitate this procedure and to reach better oncosurgical outcomes in patients with low rectal cancer. This article presents a brief summary of guidelines for treatment of patients with low rectal carcinoma. Up-to-date information about the principles of this new method, its modifications and contemporary indications is presented. Based on their own experience and literature resources, the authors inform about the advantages, limitations and unresolved issues of minimally invasive transanal mesorectal excision.


Subject(s)
Colectomy/standards , Natural Orifice Endoscopic Surgery/standards , Practice Guidelines as Topic , Rectal Neoplasms/surgery , Rectum/surgery , Anal Canal , Colectomy/methods , Humans , Natural Orifice Endoscopic Surgery/methods
12.
Rozhl Chir ; 93(10): 502-6, 2014 Oct.
Article in Czech | MEDLINE | ID: mdl-25340865

ABSTRACT

INTRODUCTION: Parastomal hernia is a common stoma complication. Surgical treatment is necessary in approximately 10 to 20% of cases. Mesh hernia repair gives significantly better results. The authors present their initial experience with laparoscopic repair of parastomal hernia using the modified Sugarbaker technique. MATERIAL AND METHODS: In the period from January 2011 to December 2013, 15 patients with a symptomatic parastomal hernia underwent laparoscopic repair with modified Sugarbaker technique. All patients had a parastomal hernia at the site of terminal colostomy after abdominoperineal resection. 14 patients underwent primary hernia repair, 1 patient was operated on for recurrence of parastomal hernia after open hernia repair. Parietex Parastomal mesh was used for hernia repair in all cases. RESULTS: Laparoscopic repair was performed successfully in all patients. The mean operating time was 45 minutes (range: 2080 minutes). The mean postoperative hospital stay was 3 days (range: 26 days). No serious postoperative complication was recorded. In the postoperative period, a recurrent symptomatic hernia was found in 1 of 15 patients (6.7%) with reintervention 17 months after primary surgery. CONCLUSION: Laparoscopic hernia repair of parastomal hernia with modified Sugarbaker technique seems to be a safe method with a very low risk of postoperative complications, including hernia recurrence. .


Subject(s)
Colostomy/adverse effects , Hernia, Ventral/surgery , Herniorrhaphy/methods , Postoperative Complications/surgery , Rectum/surgery , Surgical Mesh , Aged , Female , Humans , Male , Middle Aged , Retrospective Studies
13.
Orthopade ; 42(5): 364-6, 368-70, 2013 May.
Article in German | MEDLINE | ID: mdl-23624611

ABSTRACT

Following loss of the talus, tibiocalcaneal fusion is often the only available means of obtaining weight-bearing ability in the lower limb. Length discrepancy may be managed with an allograft. This casuistic describes 6 patients with tibiocalcaneal fusion (mean age 64 years) who had received a structural femoral head allograft fusion for failed total ankle arthroplasty (3 cases), Charcot arthropathy (2 cases) and osteomyelitis (1 case). The mean follow-up was 33 months and all limbs could be salvaged. There were two cases of non-union (one with infection). The mean AOFAS score was 51 and the mean Mazur score was 37. In the SF-36 the mean PCS was 34.4 and the mean MCS was 48.4. It was shown that in the hindfoot, as at other sites, allografts may be used for the filling of major bone defects; however, the patient function will still be massively impaired. Therefore, the procedure should be confined to cases where less complex and less invasive techniques are unlikely to be of benefit.


Subject(s)
Ankle Fractures , Arthrodesis/instrumentation , Arthrodesis/methods , Bone Nails , Calcaneus/surgery , Talus/injuries , Talus/surgery , Aged , Humans , Middle Aged , Tibia/surgery , Treatment Outcome
15.
Plant Dis ; 96(3): 437-442, 2012 Mar.
Article in English | MEDLINE | ID: mdl-30727130

ABSTRACT

A polymerase chain reaction (PCR) assay was developed amplifying a 496-bp fragment of the internal transcribed spacer region of Cephalosporium gramineum genomic DNA at concentrations of 100 fg/µl. Winter wheat seed and seedlings were collected from field plots where C. gramineum was present. Seed was tested by PCR using 20-seed samples bulked for DNA extraction. Estimates of seed infection, based on isolation of the pathogen on semiselective medium and PCR, were comparable at 0.18 and 0.13% of winter wheat 'Stephens' (P = 0.6042), and 0.45 and 0.58% of experimental line WA7970 (P = 0.5636), respectively. PCR differentiated between plants with well-developed symptoms of Cephalosporium stripe and noninoculated plants. Positive PCR was obtained from 22% of asymptomatic leaf blades from inoculated plants. We found no false positives when PCR and C. gramineum isolation on a semiselective medium were performed using tissue from the same leaf. The PCR assay has potential to diagnose Cephalosporium stripe disease prior to the appearance of symptoms. Negative PCR for some samples from which C. gramineum was isolated suggests that C. gramineum may be present below the level of detection in some asymptomatic leaves. This PCR assay may be useful for investigations into C. gramineum infection of wheat.

16.
Rozhl Chir ; 91(12): 649-53, 2012 Dec.
Article in Czech | MEDLINE | ID: mdl-23448702

ABSTRACT

INTRODUCTION: Rectocele and intussusceptions are amongst the most frequent causes of Obstructed Defecation Syndrome (ODS). ODS diagnostics has been constantly improving which results in more precise indication criteria for individual surgical approaches. The work discusses indications for Stapled TransAnal Rectal Resection (STARR) as well as the results of the seven-year follow-up. MATERIAL AND METHODS: Female patients with ODS score over 7 were indicated for STARR procedure after all conservative treatment possibilities failed. The proper indication requires that other causes of ODS be excluded. The retrospective analysis of prospectively collected data was employed. RESULTS: Between January 2005 and October 2012 29 STARR procedures for rectocele were performed. Morbidity rate of the set of our patients was 6.9%. None of the patients died. We recorded bleeding from the staple line in seven patients (without surgical revision), and urinary infection in two patients. Bleeding from staple line was present in seven causes and urinary infection was present twice. CONCLUSION: The STARR procedure seems to be an effective and safe treatment for ODS associated with rectocele and intussusception. The overall morbidity rate is low. Further investigation is required to optimize patient's selection and to reduce the potential complications and failure during postoperative period.


Subject(s)
Intussusception/surgery , Rectal Diseases/surgery , Rectocele/surgery , Rectum/surgery , Surgical Stapling , Digestive System Surgical Procedures/methods , Female , Humans , Middle Aged
17.
Z Orthop Unfall ; 149(6): 694-8, 2011 Dec.
Article in German | MEDLINE | ID: mdl-22065374

ABSTRACT

INTRODUCTION: Polyaxial angle-stable plating is thought to be particularly beneficial in the management of complex intra-articular fractures of the distal radius. The present study was performed to investigate the strength of polyaxial locking interfaces of distal radius plates. MATERIAL AND METHODS: We tested the polyaxial interfaces of 3 different distal radius plates (2.4 mm Variable Angle LCP Two-Column Volar Distal Radius Plate, Synthes, Palmar Classic, Königsee Implantate and VariAx Plate Stryker). The strength of 0° and 10° screw locking angle was obtained during static loading. RESULTS: The strength of Palmar Classic with a 0° locking angle is significantly the best of all tested systems. With a 10° locking angle there is no significant difference between Palmar Classic, Two column Plate and VariAx Plate. CONCLUSION: The strength of polyaxial interfaces differs between the tested systems. A reduction of ultimate strength is due to increases of screw locking angle. The design of polyaxial locking interfaces should be investigated in human bone models.


Subject(s)
Bone Plates , Bone Screws , Fracture Fixation, Internal/instrumentation , Radius Fractures/surgery , Wrist Injuries/surgery , Equipment Failure Analysis , Humans , Prosthesis Design , Stress, Mechanical , Tensile Strength
18.
Z Orthop Unfall ; 149(2): 206-11, 2011 Apr.
Article in German | MEDLINE | ID: mdl-20936593

ABSTRACT

AIM: Bone quality is a main factor in implant fixation. After having shown promising results, we have further investigated the use of the DensiProbe™ as an intraoperative measurement tool for evaluation of calcaneal bone quality and prediction of nailed hindfoot arthrodesis failure. METHOD: In this add-on study 19 nail arthrodeses were performed using a conventional screw plus a locked blade (n = 6) or plus a locked screw (n = 13) in the calcaneus. A specially devised tool was inserted at the fixation sites of the screws and the cancellous break-away torque was measured. The constructs were then cyclically loaded to failure. RESULTS: We saw a wide range of BMD (1.9-185.9 mgHA/cm³, mean 102.4 mg/cm³, SD 53.5). The peak torque was 0.47-1.78 Nm (mean 0.92 Nm, SD 0.46) at the proximal screw site (PSS) and 0.24 and 1.2 Nm (mean 0.63 Nm, SD 0.37) at the distal screw site (DSS), respectively, and 0.42 and 1.52 Nm (mean 1.00 Nm, SD 0.36) in the screw plus blade group (PSS). The number of cycles correlated with peak torque (two screws group PSS: p = 0.002, r² = DSS: 0.61 p = 0.001, r² = 0.90; screw plus blade group PSS: p = 0.001, r² = 0.99). Peak torque also correlated with BMD in both groups (two screws group PSS: p = 0.01, r² = 0.71; DSS: p = 0.001; r² = 0.83; screw plus blade group PSS: 0.42 and 1.52 Nm, mean 1.00 Nm, SD 0.36). CONCLUSION: A mechanical bone measurement tool like the DensiProbe™ seems to be suitable for predicting tibiotalocalcaneal arthrodesis failure in a biomechanical test set-up. As a restriction in clinical practice failure is multifactorial and prediction cannot be based upon these measurements only.


Subject(s)
Ankle Injuries/physiopathology , Ankle Injuries/surgery , Arthrodesis/instrumentation , Bone Density , Densitometry/instrumentation , Fractures, Bone/physiopathology , Fractures, Bone/surgery , Aged , Aged, 80 and over , Ankle Injuries/diagnosis , Arthrodesis/methods , Densitometry/methods , Female , Humans , Male , Middle Aged , Prognosis , Reproducibility of Results , Sensitivity and Specificity , Treatment Failure , Treatment Outcome
19.
Z Orthop Unfall ; 148(3): 309-18, 2010 May.
Article in German | MEDLINE | ID: mdl-20414866

ABSTRACT

AIM: Precise placement of the sustentaculum tali screw is essential for fixation of calcaneus fractures to achieve the best fixation strength. In the clinical practice, this procedure is demanding due to the complex anatomic configuration of the calcaneus and the limited visualisation in the intraoperative fluoroscopic images. The aim of this study was an evaluation of the accuracy for the sustentaculum tali screw placement by using different navigation procedures compared to the standard procedure. The different navigation specific workflows were evaluated and the feasibility of each procedure proven in clinical applications. METHOD: Eight sustentaculum screws per group were placed in an artifical Synbone model. Different navigation procedures were evaluated: 2D-fluoroscopy (group I), 3D-fluoroscopy (group II), fluoro-free (group III) and compared to the conventional screw placement without navigation (group IV). For each screw the time of fluoroscopy and the duration of the procedure were measured. The accuracy was evaluated postoperatively by computed tomography using axial slices and coronary as well as sagittal reformations. Furthermore, the workflow of each navigation procedure was analysed and proven in clinical applications. RESULTS: In the experimental setup, no radiation exposure was mandatory for the conventional and fluoro-free procedures, whereas mean fluoroscopy times of 17 +/- 1.03 und 66.8 +/- 0.9 were measured for 2D- and 3D-navigation procedures. In line with this, the overall mean procedure times for the screw placement were 1.26 +/- 0.05 (group IV), 3.49 +/- 0.26 (group III), 13.32 +/- 0.49 (group I) und 19.04 +/- 1.41 minutes (group II). No significant differences were observed for the accuracy of screw placement. In the clinical practice a better orientation was achieved by use of a navigation system. The fluoro-free procedure can be easily integrated into the common operation workflow, whereas the workflow of both image-based navigation procedures is technically demanding. CONCLUSION: Navigation procedures seem to be helpful for the precise placement of sustentaculum tali screws in cases of operative calcaneus fracture fixation. The kind of application to be used depends on the infrastructure of the department and the navigation-experience of the operating room team. Whereas the fluoro-free procedure is intuitive in use, the 2D-navigation does not justify the extra efforts. The 3D-procedure is the recommended application for surgeons familiar with navigation, providing the best orientation due to the slice image visualisation in all three dimensions.


Subject(s)
Ankle Injuries/surgery , Bone Screws , Calcaneus/injuries , Calcaneus/surgery , Fractures, Bone/surgery , Surgery, Computer-Assisted/methods , Ankle Injuries/diagnosis , Feasibility Studies , Fractures, Bone/diagnosis , Humans , Prosthesis Implantation/methods , Treatment Outcome
20.
Z Orthop Unfall ; 147(4): 445-51, 2009.
Article in German | MEDLINE | ID: mdl-19693741

ABSTRACT

AIM: The purpose of this study was to evaluate the first clinical experiences with the newest generation retrograde arthrodesis nail. METHODS: 28 patients who had tibiotalocalcaneal arthrodesis between 2005 and 2007 using a retrograde compression nail fixation (T2 AAN, Stryker, Duisburg, Germany) were retrospectively reviewed. Complications, functional outcome scores, and patient satisfaction were determined and the radiographs were evaluated for bony healing. RESULTS: The mean time interval until follow-up was 16 months (range: 7-27). All but 1 ankle showed a radiographically healed arthrodesis. 25 patients (89 %) were satisfied with the outcome. The average functional scores at follow-up were 64 (38-86 points) points for the American Orthopedics Foot and Ankle Score (AOFAS) and 65 points for the Mazur Ankle Scoring System (30-83 points). We recorded complications in 7 patients (25 %) including 1 deep infection with breakage of the calcaneus screw, 3 reinfections, 1 deep vein thrombosis, 1 intraoperative fracture of the tibia, 1 delayed union and 1 non-union. CONCLUSION: Tibiotalocalcaneal arthrodesis is a salvage procedure. Using a specifically designed retrograde intramedullary nail is a reliable method to achieve fusion. Patient satisfaction is high, but the procedure is demanding and complications are frequent. After infections the indication for nail arthrodesis should be evaluated carefully in each case.


Subject(s)
Arthrodesis/instrumentation , Arthrodesis/methods , Bone Nails , Foot Deformities/surgery , Adult , Aged , Female , Humans , Male , Middle Aged , Treatment Outcome
SELECTION OF CITATIONS
SEARCH DETAIL