Understanding the role of facets and twin defects in the optical performance of GaAs nanowires for laser applications.

GaAs nanowires are regarded as promising building blocks of future optoelectronic devices. Despite progress, the growth of high optical quality GaAs nanowires is a standing challenge. Understanding the role of twin defects and nanowire facets on the optical emission and minority carrier lifetime of GaAs nanowires is key for the engineering of their optoelectronic properties. Here, we present new insights into the microstructural parameters controlling the optical properties of GaAs nanowires, grown via selective-area metal-organic vapor-phase epitaxy. We observe that these GaAs nanowires have a twinned zinc blende crystal structure with taper-free {110} side facets that result in an ultra-low surface recombination velocity of 3.5 × 104 cm s-1. This is an order of magnitude lower than that reported for defect-free GaAs nanowires grown by the vapor-liquid-solid technique. Using time-resolved photoluminescence and cathodoluminescence measurements, we untangle the local correlation between structural and optical properties demonstrating the superior role of the side facets in determining recombination rates over that played by twin defects. The low surface recombination velocity of these taper-free {110} side facets enable us to demonstrate, for the first time, low-temperature lasing from bare (unpassivated) GaAs nanowires, and also efficient room-temperature lasing after passivation with an AlGaAs shell.

Efficacy of 3-D-imaging in minimally-invasive screw fixation of proximal phalanx fractures: A cadaveric study.

The current study evaluated whether 3-D fluoroscopic imaging is capable of adequate visualisation, reduction and effective guidance of implant placement during a minimally-invasive screw-fixation (MISF) procedure in the treatment of proximal phalanx fractures. A comparison with conventional intraoperative 2-D imaging was performed in a cadaveric model. Conventional 2-D and 3-D imaging series were performed following the creation of proximal phalanx fractures, reduction and fixation, pre- and post-operatively. For both imaging modalities, attention was paid to A) correct reduction, B) screw-placement and, if present, C) intra-articular offset of fracture edges.The results revealed no related overall advantage of the 3-D imaging system over normal 2-D fluoroscopy at the proximal phalanx region. The authors conclude that, given the cost of 3-D imaging technology, as well as the increased time required for image acquisition, its routine use in the treatment of phalanx fracture cases is not justifiable at present.

Results of total aponeurectomy for Dupuytren's contracture in 61 patients: a retrospective clinical study.

INTRODUCTION: Many surgical techniques have been advocated to treat Dupuytren's contracture. Partial fasciectomy is often performed to treat the whole spectrum of Dupuytren's disease. METHOD: We have reviewed the effectiveness of total aponeurectomy performed on 61 patients [10 women and 51 men (male:female ratio 5.1:1) with a mean age of 63.0 (range 42-79 years) and a mean follow-up of 3.45 years (range 1.03-6.39 years)]. RESULTS: Post-operative complications including haematoma, seroma or necrosis were found in 13.8% of the patients. Recurrence of contracture occurred in 10.8% of the patients and 4.6% of the operated patients presented with a nerve lesion. Nerve irritation occurred in 6.2% of the patients. The mean DASH-score was 3.85 (range 0-52.5). Family pre-disposition was an important risk factor for Dupuytren's disease with 44.3% of patients having a positive family history. CONCLUSION: We suggest that total aponeurectomy is a promising alternative to partial fasciectomy with low risk for a recurrence and slightly increased risk for a nerve lesion.

Arthrodesis of the distal interphalangeal joint: description of a new technique and clinical follow-up at 2 years.

INTRODUCTION: Arthrodesis of the distal interphalangeal joint (DIPJ) is an accepted operative procedure to treat osteoarthritis, instability and joint deformity. There is a wide spectrum of recommended operative techniques including cerclage wires, headless screws, bio-resorbable pins and lag screws. Lag screw fixation remains one of the most accepted methods of fixation; however, problems can occur in particular subsidence of the screw head leading to loss of compression and prominence of the screw head in the finger tip necessitating removal. We describe here a new technique of DIPJ arthrodesis that avoids these problems. METHODS AND PATIENTS: The technique is described here in detail, and clinical results are given for 18 joints (17 patients) followed-up at a mean 24 months (range 6-44). RESULTS: Mean post-operative DASH score was 15. There were no cases of non-union; only four complications were seen, one case of nail growth disturbance and one of early screw breakage necessitating revision. Two infections necessitated early hardware removal although both arthodesis were united. CONCLUSION: The technique is simple and reliable giving consistent clinical results.

[Self-active physical thrombosis prophylaxis in the patients' bed with the Phlebostep: acceptance and measurement of venous blood flow in immobilized patients]. / Eigenaktive physikalische Thromboseprophylaxe im Patientenbett mit dem Phlebostep : Akzeptanz und venöse Flussmessung beim immobilisierten Patienten.

BACKGROUND: Despite the broad use of low molecular weight heparin, deep vein thrombosis is still a relevant risk for immobilized patients in orthopedic surgery. Patients can reduce this risk by active training exercises with a muscle pump. The aim of this study was to test the acceptance and effect of a self-developed training device to accelerate venous return as well as a technical optimization. The device was installed for in-patients in orthopedic and traumatology departments. PATIENTS AND METHODS: A simple pillow-like device was developed, which can be positioned against the foot end of the patient's bed (Phlebostep). The device gives a sound-based feedback to the patient while pushing actively against it with complete ankle flexion. A digital integrated counter device allows direct feedback to the physician and nursing staff at any time. Initial testing including duplex sonography for venous flow measurements were done on 10 orthopedic in-patients. Prior testing on 7 healthy volunteers was carried out to define the effect of various amounts of pressure on the Phlebostep on the venous blood flow. Additionally, a questionnaire on the general acceptance and user-friendliness was filled out by 84 patients who had used the Phlebostep. RESULTS: The optimal pressure force was defined as 35 mmHg for further measurements. The venous flow measurements in the 10 postoperative patients revealed an increased venous blood flow in the affected leg by an average of 99.9%. Analysis of the questionnaire from the 84 patients showed a high degree of acceptance. CONCLUSION: In addition to the technical feasibility, this study showed that use of the Phlebostep resulted on average in a doubling of venous return. The increase of venous flow offers an additional effective device for thrombosis prophylaxis through patient's own active movements and is clearly superior to the use of devices such as antithrombosis stockings alone. The Phlebostep found a high degree of acceptance with the patients.

Modified syringe design prevents plunger-related contamination--results of contamination and flow-rate tests.

The usual mechanism for syringe contamination is spread of micro-organisms along the inside of the barrel. Two or more full strokes of the plunger will inevitably transport a contaminant from the inside wall into the sterile compartment. We modified syringes by replacing the plunger with a modified version that has an additional central O-ring seal. Conventional and modified syringes were tested for their susceptibility to contamination using standard microbiological and radioisotope methods, and the flow-rate stability of the modified syringe design was assessed in a model with commercially available infusion pumps. Although conventional syringes consistently became contaminated with the second full excursion of the plunger, no contamination was observed in modified syringes, even after 100 aspiration/injection cycles. With respect to flow-rate stability, the new syringe design complies with DIN (German Institute for Standardization) standards.

[Combination of ipsilateral supracondylar humeral- and forearm fractures in children]. / Ipsilaterale knöcherne Begleitverletzungen bei kindlichen suprakondylären Humerusfrakturen - Diagnostik, Therapie und Versorgungsergebnisse -

In an 11-year period, from 01. 08. 1987 to 31. 08. 1998, a total of 72 children (mean age 7.6 years, range 2-12 years) with dislocated supracondylar humeral fractures were treated surgically in the Department for Traumatology, University Hospital, Essen. The combination of supracondylar humeral fracture and ipsilateral forearm fracture occurred in 8 children (11.1 %). 4 revealed a complete forearm fracture in the distal third, 4 children a fracture of the distal physis (Salter-Harris type II). The supracondylar humeral fractures were reduced openly via a single lateral approach and stabilized by crossed K-wire fixation. The distal forearm fractures were treated by closed reduction and percutaneous pinning. Fractures of the distal physis were treated by closed reduction and application of an above elbow cast. Excellent results were achieved in all children with ipsilateral supracondylar and forearm fractures.

Results of flexor tendon repair of the hand by the motion-stable wire suture by Towfigh.

We compared the motion-stable wire suture by Towfigh (MSWST) with a modified Kessler suture (MKS) by following up flexor tendon repairs (MSWST, n = 21/39 digits; MKS, n = 20/31 digits). For MSWST we found 31 (79.5%) "excellent", 3 (7.7%) "good", and 5 (12.8%) "fair" results, when using the scoring system of Buck-Gramcko. In 3 (14.3%) patients the MSWST had to be removed owing to local irritation. In a further 3 (14.3%) patients, this was done when secondary tenolysis was necessary. The latter was also performed in 4 (20.0%) patients in whom the MKS was used. Here we found 23 (74.2%) excellent, 7 (22.6%) good, and 1 (3.2%) fair result. The statistical evaluation of the data concerning the patients' age, sex, the involved zone, the side, and the functional outcome did not reveal a significant difference (P < 0.05) between both groups and the chosen type of repair. The results of MSWST and MKS are similar, but MSWST allows early motion therapy without a splint or rubber-band protection.

Adaptation of Ilizarov ring fixator to the economic situation of developing countries.

Especially in countries with low per capita income, poor patients with open fractures and non-unions are unable to purchase modern, commercially produced surgical implants. To alleviate this situation, we initiated the production of a locally made ring fixator. The rings were cut from tubes cast from scrap aluminium. It was applied in 40 patients to test its utility for the typical indications for the Ilizarov technique. The fixator was tolerated well. All fractures united except in one case where there was refracture of the consolidate due to too early removal of the fixator. Two arthrodeses were successful. Bone transport showed adequate regeneration. A single radial non-union united successfully. Loosening occurred in 11 wires and breakage in 6. The subacute infections in 11 (27.5%) patients were not due to the fixator itself but to low standards of hygiene and the delay of treatment in the prehospital phase. Reusing the fixator at least three times reduces the cost for the individual patient to US$ 13.60. A locally made fixator is cost-effective and can be recommended for surgical treatment under similar economic situations.

Grading of functional results of elbow joint arthrolysis after fracture treatment.

In the treatment of posttraumatic contracture of the elbow joint, arthrolysis is a proven procedure. We used a stepwise operative approach starting laterally and including an additional medial and dorsal incision if needed. A total of 91 patients with arthrolysis of the elbow could be followed-up on average 44 months (range 9-102 months) joint after operative (58, 63.7%) and non-operative (33, 36.3%) fracture treatment. The mean preoperative range of motion (ROM) in flexion/extension was 49 degrees (SD +/- 38 degrees), while in pronation/supination it was 89 degrees (SD +/- 66 degrees). Postoperatively, the ROM was on average 94 degrees (SD +/- 27 degrees) in flexion/extension and 129 degrees (SD +/- 52 degrees) in pronation/supination. Using our own grading system, it became evident that most patients had a functional benefit from the procedure, although the quality of the improvement differed. For example, postoperatively 59.3% of the patients were grade I (> or = 90 degrees) in flexion/extension compared with 16.5% preoperatively. Although the rest also showed improvements, their functional benefit was less. The earlier the release of the joints was performed, the better was the functional outcome (p < 0.05). The importance of an intensive early rehabilitation programme is emphasised while indications for this procedure should only be seen in compliant patients.

[Surgical management of type III thoracic shotgun injury]. / Chirurgisches Management des thorakalen Schrotschusses Typ III.

Reporting the case of a short-range severe thoracic shotgun injury the differentiated management of this trauma is discussed. Indication for operative exploration under emergency conditions is hemorrhagic shock, perforation of esophagus/stomach and pericardial tamponade. Even under a toxicological point of view there is no indication for emergency revisions.

[Lengemann suture versus bone screw osteosynthesis in treatment of ulnar osseous collateral ligament rupture of the thumb metacarpophalangeal joint]. / Lengemann-Naht versus Schraubenosteosynthese bei der Behandlung des ulnaren knöchernen Seitenbandausrisses am Daumengrundgelenk.

Out of 95 ligamentous lesions of the thumb metacarpophalangeal joint, those with an isolated bony rupture of the ulnar collateral ligament were chosen. Of these, 15 patients treated with Lengemann suture and 16 with screw fixation were followed-up on average 27.3 and 26.4 months, respectively, after operative treatment. Under only "good" and "very good" clinical results, the statistical analysis of the objective and subjective parameters showed no significant difference, except for the measurement of the soft-tissue circumference (p < 0.01) between either procedure. Although both procedures have a low rate of complications, screw fixation is preferable since implant removal is not necessary.

[How many severely injured multiple-trauma patients can benefit from the biomechanical advantage of early mobilization following femoral intramedullary nailing?]. / Wieviel schwermehrfachverletzte Patienten können den biomechanischen Vorteil der Frühbelastbarkeit nach Femurmarknagelung nutzen?

The benefit of early operative stabilization of femoral fractures is established in patients with multiple injuries. In the last few years the unreamed femoral nail is favoured for internal fixation of femoral fractures despite pathophysiological concerns. The foremost advantage of femoral nails compared with plate fixation is the possibility of early full weight bearing. The aim of this retrospective study was to investigate, under consideration of the severity of injury, the extent of injury, and the clinical course, if multiple injured patients with concomitant femoral fractures benefit from the preferred intramedullary nailing with early weight bearing. Three hundred and two (23.8%) out of 1271 multiple injured patients (ISS > 17) had a concomitant femoral fracture. Fourty-seven out of 302 patients were children under 16 years of age, remaining 255 patients. Eighteen out of 255 patients died within the first 21 days after trauma and 66 patients required mechanical ventilation for more than three weeks (171/255). Thirty patients suffered from severe head injury (AIS-head > 3) and seven from severe pulmonary contusion with concomitant abdominal injury (134/255). Two patients had grade III open femoral fractures with vascular injury. Ipsilateral unstable pelvic fractures were seen in 11 patients, seven patients had ipsilateral intraarticular femoral fractures, and ipsilateral intraarticular fractures of the lower leg or foot were observed in 40 patients (74/255). The results demonstrate, that only 74 (29%) out of 255 multiple injured patients (> 16 years of age) had a theoretical benefit of early weight bearing. Seventy percent of the patients did not benefit from intramedullary nailing considering full weight bearing. With regard to pathophysiological concerns alternative methods of fracture fixation should be discussed for these patients. Primary fracture fixation with external fixators and secondary internal fixation proved to be a save alternative method. The complication rate of plating is comparable to intramedullary nailing but associated with less severe systemic risks. Primary plating of femoral fractures would not delay mobilization of most multiple injured patients.

[Results of cement-free implanted, Robert Mathys isoelastic acetabular cup]. / Ergebnisse der zementfrei implantierten, isoelastischen Hüftpfanne nach Robert Mathys.

In 163 patients--125 (76.7%) female, 38 (23.3%) male--172 cementfree isoelastic acetabular cups were implanted. The average patient age was 72.6 years (range: 16 to 96 years). Sixty-seven (41.1%) patients with 72 (41.9%) cups could be followed-up for an average of 6.0 years (range: 2.0 to 12.2 years) after the procedure. Using the Harris-hip-score we found 49 (68.1%) "very good" to "fair" results. In 23 (31.9%) hips scoring had to be classified as "bad". The rate of cup-loosenings in the collective was low at 3.5% (6/172), probably due to the reduced physical activity of our comparatively older patients. Because after the 8th year symptomatic loosening must be routinely expected, the procedure is not indicated for younger patients. In older patients with femoral neck fractures the cementfree isoelastic acetabular cup has proven itself effective in our experience.

[Acceptance of Allgöwer/Wenzl partial dynamic weight bearing orthosis. Results using a hidden step counting device]. / Akzeptanz der dynamischen Teilbelastungsvorrichtung nach Allgöwer/Wenzl. Ergebnisse der Anwendung eines verdeckten Schrittzählers.

In 30 patients (12 male and 18 female) with extensive lesions of the cartilage of the upper and lower ankle joint, controlled partial-loading of the lower extremity was established by means of the load-relieving orthosis by Allgöwer and Wenzl. In these orthoses a hidden step-counter could be integrated. Average patient age was 46 (range 20 to 74) years. The load-relieving orthosis was used on average for 68 (range 22 to 98) days with a mean of 10,756 steps (range: 261 to 30,538); respectively 158 steps per day. Neither age, sex, diagnosis nor the duration of complete postoperative immobilisation correlated with the number-of-steps-per-diem compliance (r > +0.22).

[Late results of surgical treatment of capsular ligament injury of the thumb metacarpophalageal joint]. / Spätergebnisse der operativen Behandlung der Kapselbandverletzung des Daumengrundgelenkes.

48 patients with 49 lesions of the ligamentous apparatus of the thumb metacarpophalangeal joint were followed-up on average 32.4 months after operative treatment. Using our own scoring and grading, we evaluated the operative results by subjective and objective criteria. In 47 (95.9%) of the operated first metacarpophalangeal joints we found "very good" and "good" results. Only one (2.0%) patient showed either a "fair" or "poor" result. The statistic analysis of the examined parameters range of motion, strength of grip, and stability did not show significant differences to the uninjured side. We recommend the use of Lengemann suture.

[Magnetic resonance tomography evaluation of the lower limb after compartment syndrome]. / Magnetresonanztomographische Beurteilung des Unterschenkels bei Zustand nach Kompartmentsyndrom.

For the purpose of follow-up of the disease as well as the availability of magnetic resonance imaging (MRI) as a method for diagnosing soft tissue changes 20 patients with imminent and manifest compartment syndrome were examined for their fluid content of the lower limb. Considering the normal side as well as 10 healthy volunteers a significant reduction of fluid content was diagnosed in the manifest compartment syndrome after fasciotomy in the late phase of disease (r = 0.49, p > 0.005, n = 29). This was interpreted as a sign of fibrosis. The patients with imminent compartment syndrome and fasciotomy (r = 0.83, p > 0.001, n = 19) demonstrated no significant changes compared to the normal volunteers (r = 0.91, p > 0.001, n = 40) as well as the normal compartments of the diseased lower extremities (r = 0.85, p > 0.001, n = 32). MRI is a useful method in the examination of soft tissue changes and underlines the importance of an early fasciotomy in case of imminent compartment syndrome.

[The traumatized shoulder in computerized and magnetic resonance tomography]. / Die traumatisierte Schulter in der Computer-und Magnetresonanztomographie.

Diagnosis of traumatic changes of the shoulder can be achieved by several invasive and nonivasive radiological procedures allowing visualization of bony and/or soft tissue structures. With reference to 74 shoulder examinations CT, CT-arthrography, and MRI were reviewed and their value for further treatment assessed. Since joint effusions occurred in nearly all cases of glenoid and rotator cuff lesions, a cost-effective strategy for diagnosing traumatic changes of the shoulder is presented.