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Insertion gain measured with three probe tube systems.

The study consisted of two experiments on the insertion gain measured with probe tube microphones. In experiment I, the insertion gain of the same mild gain hearing aid was measured twice on 12 subjects using three commercially available probe tube systems. Test-retest measurements were made by two different examiners. Mean test-retest differences were all less than 4 dB with 95% critical differences for these measures varying from approximately 3 to 8 dB depending upon the test system used. In experiment II, the three sets of probe tube measures of insertion gain were compared to behaviorally measured functional gain in 7 hearing-impaired subjects at several frequencies. There were no significant differences among the probe tube measures of insertion gain or between these measures and functional gain. Functional gain was significantly correlated with probe tube insertion gain for each device at frequencies from 500 through 4000 Hz.

Acoustics↗

Measuring the real-ear to coupler difference transfer function with an insert earphone and a hearing instrument: are they the same?

OBJECTIVE: The purpose of the study was to compare the real-ear to coupler difference (RECD) measured with an insert earphone and two models of hearing instrument. DESIGN: The RECD was obtained from one ear of 18 normal-hearing subjects by subtracting the 2-cc coupler (HA1 and HA2) response from a real-ear aided response, using a conventional probe-tube microphone system. The measurements were made with a conventional ER-3A earphone and two models of behind-the-ear hearing instrument (Unitron US80, Unitron, Kitchener, Canada; and Widex Diva, Widex, Vaerloese, Denmark). RESULTS: The procedures were very reliable, with mean differences on retest of less than 1 dB. There were statistically significant differences between the mean RECDs obtained using an insert earphone compared with those obtained with each hearing instrument (p < 0.05). The differences were greatest when using the HA2 2-cc coupler. For example, the maximum difference in mean RECD between the insert earphone and the Widex Diva was 6 dB and 11 dB when using the HA1 and the HA2 2-cc coupler, respectively. CONCLUSIONS: The RECD is dependent on the acoustic impedance of the sound source, the coupling system, and the coupler and ear. The acoustic impedance may be different for an insert earphone and a given hearing instrument. Therefore, the RECD measured with an insert earphone may not always accurately represent the difference in performance of a hearing instrument measured in the real ear and the 2-cc coupler.

Acoustic Impedance Tests↗

Osteosynthesis of metastatic lesions of the proximal femur with a solid femoral nail and interlocking spiral blade inserted without reaming.

OBJECTIVES: To evaluate the efficiency of a solid femoral nail and interlocking spiral-blade, inserted without reaming (UFN/ spiral blade, Synthes-Stratec, Oberdorf, Switzerland), for the fixation of pathologic and impending pathologic fractures of the proximal femur, particularly those involving the subtrochanteric area. DESIGN: Retrospective, consecutive series. SETTING AND PATIENTS: All patients treated for pathologic and impending pathologic fractures of the trochanteric or subtrochanteric area, stabilized using a UFN/spiral blade, inserted without reaming, from June 1994 to June 1997. INTERVENTION: Femoral intramedullary nailing was performed without reaming on a radiolucent operating room table. The nail was inserted through a five-centimeter supratrochanteric approach, and the interlocking spiral-blade device was introduced percutaneously. METHODS: The following parameters were assessed: pathology reports, location of bone lesions, patient survival, pain relief, ambulation, hardware failure on successive radiographs, and intraoperative complications. RESULTS: Twelve pathologic and impending pathologic fractures were stabilized in ten patients. Two patients required bilateral nailing that was staged with intervals of two and three weeks, respectively. The average postsurgical survival was six and one-half months. No implant failure was noted, and no surgical revision was performed. One intraoperative death occurred during surgery and was documented on autopsy as massive pulmonary fat embolization. Neither patient with bilateral nailing suffered from fat embolism syndrome. CONCLUSIONS: Femoral nail insertion without reaming using an interlocking spiral blade provides appropriate stabilization of the proximal femur in case of metastatic lesions, even with extensive subtrochanteric involvement. Although the nails were inserted without reaming, this did not avoid the risk of fat embolization syndrome. This study only addressed results in patients with short-term survival.

Activities of Daily Living↗

The needle-wire-dilator technique for the insertion of chest tubes in pediatric patients.

We evaluated the needle-wire-dilator (NWD) technique, using commercially available sets, for insertion of chest tubes in 24 pediatric patients who were admitted to our pediatric intensive care unit (PICU). Fourteen patients had pneumothoraces, three had hemothoraces, two had pneumonia with empyema, four had pleural transudate effusions, and one had chylothorax. The ages of the patients ranged from four months to 24 years, and the sizes of the inserted chest tubes ranged from 10F to 20F. All insertions were successful, and the time from invasion of the pleural space by the needle to completion of chest tube insertion and connection to the tubing drainage system ranged from four to seven minutes. In four patients the procedure had to be performed while a significant coagulopathy existed. However, none of the 24 patients developed hemorrhagic complications. The only complication observed was a kink in the chest tube in five patients, resulting in recurrence of pneumothorax in four and pleural effusion in one. These adverse occurrences were corrected by repositioning the chest tubes in three patients, and by replacing the chest tubes with the stiffer, trochar type, chest tubes in the other two. We conclude that the NWD technique for chest tube insertion is quick, safe, and easy to perform in all pediatric age groups. The commercially available chest tubes used in our study were somewhat softer than the trochar type chest tubes available, which explains the occurrence of kinks in some of them.

Adolescent↗

Insertion of long lines in the pediatric emergency department.

OBJECTIVE: The purpose of this study was: 1) to evaluate the role of the pediatric emergency department (PED) in placing peripherally inserted midline or central catheters (long lines), and 2) to review indications and complications to use this technology to reduce the number and duration of admissions and provide an alternative method for administering intravenous therapy. METHODS: Retrospective chart review of all patients taken from a procedure log who had long lines placed in the emergency department of a children's hospital. RESULTS: Twenty-eight patients had 30 long line insertions over a 36-month period. Fourteen were female; age ranged from 1 to 36 years with a median of 9 and a mean of 11.1 +/- 8.4. The indication for insertion was for parenteral antibiotics in 27 of 28 (96%) patients and for parenteral nutrition in 1 (4%) patient. The catheters varied in length from 8 to 60 cm. Twelve of 30 (40%) catheters terminated centrally in the subclavian or superior vena cava, while 18 (60%) were in the peripheral cephalic, basilic, or axillary veins. Chest radiography confirmed positioning in 12 of 12 inserted centrally and in 15 of 18 (83%) in the peripheral circulation. Half of the patients received no premedication for the procedure; 10 (33%) received topical anesthetic cream; 2 (7%) local infiltration of anesthetic, and 2 (7%) parenteral sedation. Twenty-one of 30 (70%) patients were discharged directly from the emergency department; 3 (10%) were discharged after admission to the hospital to complete treatment at home with their long lines, and 6 (20%) used their long lines for in-hospital therapy only. Eight of 30 (27%) placements were for patients specifically referred to the PED for placement or replacement of a long line. Twelve of 30 (40%) lines were placed in children presenting for intravenous therapy for cellulitis. These patients received a long line with home i.v. therapy instead of the traditional admission. The duration of intravenous treatment documented for all patients ranged from 1 to 62 days with a median of 10.5, and a mean of 16.2 +/- 17.8, compared with the duration of the line ranging from 1 to 28 days with a median of 4, and a mean of 7.3 +/- 8.0. Ten of 30 (33%) had their line for 3 days or less. The short duration was due to problems with line function in 5 of 10, and intentional removal secondary to improved cellulitis in 5. There were no significant complications with the lines reported during placement or while in use; however, 8 of 30 (27%) of the lines placed developed problems with function, requiring repair or replacement. CONCLUSIONS: 1) Long lines can be inserted in the pediatric emergency department by physicians with different levels of training with minor complications and no adverse clinical effects; 2) the placement of long lines can eliminate the need for hospitalization in some cases, reduce the duration of hospitalization in others, and lessen the need for repeated venipunctures for routine peripheral catheter replacement in patients requiring i.v. therapy; 3) the planned duration of therapy as well as other factors not analyzed in this study should be considered when selecting patients for long line placement in the emergency department.

Adolescent↗

Flexion failure of posterior cervical lateral mass screws. Influence of insertion technique and position.

STUDY DESIGN: The strength of posterior cervical lateral mass fixation was evaluated in a cadaver model for two techniques of screw insertion. OBJECTIVE: To compare the flexion failure strengths of posterior cervical plate fixation for two techniques of screw placement at the superior and inferior screw hole positions, and to evaluate the effect of bone mineral density on fixation strength. SUMMARY OF BACKGROUND DATA: Biomechanical analyses of various screw insertion techniques for posterior cervical lateral mass fixation have never evaluated the effect of screw position along the plate. METHODS: Individual C3-C6 segments of 24 human cadaveric cervical spines were used. The spinous process and lamina were removed to simulate a postlaminectomy situation. Vertebral body bone mineral density for each specimen was determined by dual-energy radiograph absorption scanning. In each lateral mass, a bicortical 3.5-mm screw was placed using either the Magerl or Roy-Camille insertion technique through an end hole of a titanium bone plate. For "superior" screws, the plate was directed caudally; for "inferior" screws, the plate was directed cranially. Screw violation of the surrounding facet joint was noted. An increasing flexion moment was applied by loading the plate 4 cm from the screw head at a rate of 10 cm/min using a servohydraulic testing machine until screw failure. RESULTS: For the superior screw hole position, the Magerl screw sustained a significantly higher average moment to failure (190.2 Ncm) than the Roy-Camille screw (138.7 Ncm; P < 0.05). For the inferior screw hole position, there was no significant difference in flexion failure strength between the two techniques (Magerl screws, 287.7 Ncm; Roy-Camille screws, 308.2 Ncm). For each insertion technique, inferior screws were nearly twice as strong as superior screws (P < 0.01). Violation of the inferior articular process occurred with 53% of Roy-Camille screws and with none of the Magerl screws. Lateral mass fracture on screw insertion occurred with 6% of the Roy-Camille screws and with 7% of the Magerl screws. Significant correlation between screw path length and load to failure was found only at the superior screw hole position. Correlation with vertebral body bone mineral density was significant at both positions. CONCLUSIONS: The Magerl technique has advantages over the Roy-Camille technique for placing the end screws when performing posterior cervical lateral mass plate fixation, providing greater strength superiorly and not violating unfused facet joints inferiorly. Evaluation of bone mineral density by dual-energy radiographic absorption scanning is predictive of failure strength for both test modes.

Biomechanical Phenomena↗

Iliolumbar ligament insertions. In vivo anatomic study.

STUDY DESIGN: Using magnetic resonance imaging, this study analyzed the anatomic characteristics of the iliolumbar ligament insertion on humans. OBJECTIVES: To resolve certain anatomic questions about the manner of insertion of the iliolumbar ligament. SUMMARY OF BACKGROUND DATA: The data of the postmortem studies of the iliolumbar ligament are controversial because of the number, complexity, and variability of the structures present in the lumbosacral region. METHODS: Twenty-eight iliolumbar ligaments of 14 adult volunteers were analyzed with magnetic resonance imaging. The images were acquired along the transversal planes (from inferior to superior) and coronal planes (from the ventral to the dorsal) of the lumbosacral region. RESULTS: The anterior band of the iliolumbar ligament (broad and flat) originates from the anterior-inferior-lateral part of the L5 transverse process and expands as a wide fan before inserting on the anterior part of the iliac tuberosity below the posterior band. The posterior band of the iliolumbar ligament originates from the apex of the L5 transverse process and is thinner than the anterior with a round section, and it inserts on the iliac crest (from the anterior margin to the apex). CONCLUSIONS: The minor width of the area of insertion on the iliac crest of the posterior band (and therefore its lower resistance with the mechanical overloads) could explain the frequency of the painful syndromes related, by some authors, to an enthesopathy of this ligament.

Adult↗

Improved accuracy of pedicle screw insertion with computer-assisted surgery. A prospective clinical trial of 30 patients.

STUDY DESIGN: A prospective clinical trial was done to study the accuracy of pedicle screw placement in 30 consecutive computer-assisted orthopedic surgeries. OBJECTIVES: To determine the accuracy and clinical applicability of this new method for pedicle screw insertion. SUMMARY OF BACKGROUND DATA: Conventional screw insertion techniques have been associated with high pedicle screw malplacement rates in cadaver studies and clinical studies with postoperative computed tomography evaluation. METHODS: Thirty transpedicular, low-back, titanium instrumentations were performed with computer-assisted orthopedic surgery. The accuracy of screw placement was evaluated using a sophisticated computed tomography protocol. RESULTS: The total number of pedicle screws was 174. Of these, 139 (79.9%) could be inserted with computer-assisted orthopedic surgery. The malplacement rate of computer-assisted orthopedic surgery screws was 4.3%. In screws that were not inserted by computer-assisted orthopedic surgery, the malplacement rate was 14.3%. One malplaced screw that had not been inserted with computer-assisted orthopedic surgery caused L4 root paresis. CONCLUSIONS: The accuracy of pedicle screw placement using computer-assisted surgery proved to be superior to the accuracy obtained when using conventional techniques.

Bone Screws↗

Cervical pedicle screws: comparative accuracy of two insertion techniques.

STUDY DESIGN: Independently assessed radiographic and anatomic comparison of device implantation methods. OBJECTIVES: To compare the relative accuracy of two techniques of inserting cervical pedicle screws. SUMMARY OF BACKGROUND DATA: In an attempt to define the anatomic risks of cervical pedicle screw insertion, image-guided stereotactic technology was shown to be superior to some other methods in vitro.- Meanwhile, in vivo experience with Abumi's technique of screw insertion has had few clinically relevant instances of screw malposition. There has been no direct comparison between current image-guided technology and Abumi's fluoroscopically assisted technique. METHODS: The pedicles (C3-C7) of human cadaveric cervical spines were instrumented with 3.5-mm screws with either of two techniques. Cortical integrity and potential neurovascular injury were independently assessed by computed tomographic (CT) scans and anatomic dissection. A cortical breach was considered "critical" if the screw encroached on any vital structure. If any part of the screw violated the cortex of the pedicle but no vital structure was at risk for injury, the breach was classified as "noncritical." RESULTS: In Group I (StealthStation; Sofamor-Danek, Memphis, TN), 82% of screws were placed in the pedicle, and 18% had a critical breach. In Group II (Abumi technique), 88% of screws were placed in the pedicle, and 12% had a critical breach. No statistically significant differences were demonstrated between each group (P = 0.59). Regarding pedicle dimensions and safety of insertion, a critical pedicle diameter of 4.5 mm was determined to be the size below which a critical breach was likely, but above which there was a significantly greater likelihood for safe screw placement. The most common structure injured in each group was the vertebral artery. CONCLUSIONS: The use of a computer-assisted image guidance system did not enhance safety or accuracy in placing pedicle screws compared with Abumi's technique. Both techniques have a noteworthy risk of injuring a critical structure if inserted into the pedicles with a diameter of less than 4.5 mm. Under laboratory conditions, pedicles with a diameter of more than 4.5 mm have a significantly greater likelihood of being safely instrumented by either technique. These data indicate that cervical pedicle screw placement is feasible, but it should be reserved for selected circumstances with clear indications and in the presence of suitable pedicle morphology.

Bone Screws↗

Chondral metaplasia in calcific insertional tendinopathy of the Achilles tendon.

OBJECTIVE: To ascertain whether tendon samples harvested from patients with calcific insertional Achilles tendinopathy showed features of failed healing response, and whether abnormal quantities of type II collagen had been produced in that area by these tenocytes. DESIGN: Comparative laboratory study. DESIGN: University teaching hospitals. PATIENTS: Tendon samples were harvested from eight otherwise healthy male individuals (average age 47.5+/-8.4 years, range 38 to 60) who were operated for calcific insertional Achilles tendinopathy and from nine male patients who died of cardiovascular events (mean age 63.1+/-10.9 years) while in hospital. INTERVENTIONS: Open surgery for calcific insertional Achilles tendinopathy. MAIN OUTCOME MEASURE: Semi-quantitative histochemical, immunohistochemical, and immunocytochemical methods to ascertain whether tendinopathic tendons were morphologically different from control tendons, and whether abnormal types of collagen were produced. RESULTS: Tenocytes from tendons from patients with calcific insertional Achilles tendinopathy exhibit chondral metaplasia, and produce abnormally high quantities of collagen type II and III. CONCLUSIONS: The altered production of collagen may be one reason for the histopathological alterations described in the present study. Areas of calcific insertional Achilles tendinopathy have been subjected to abnormal loads. These tendons may be less resistant to tensile forces. Further studies should investigate why some tendons undergo these changes.

Achilles Tendon↗

A novel genotype encoding a single amino acid insertion and five other substitutions between residues 64 and 74 of the HIV-1 reverse transcriptase confers high-level cross-resistance to nucleoside reverse transcriptase inhibitors. Abacavir CNA2007 International Study Group.

We investigated HIV-1 reverse transcriptase (RT) polymorphisms of plasma isolates from 98 HIV-1-infected study subjects with >2 years of antiretroviral therapy who were failing their current protease inhibitor (PI)-containing regimen. In 1 patient, we detected a virus with a heavily mutated beta3-beta4 connecting loop of the HIV-1 RT fingers subdomain, consisting of a single aspartate codon insertion between positions 69 and 70 and five additional variations: 64N, K65, K66, 67G, 68Y, T69, Ins D, 70R, W71, R72, K73, 74I. Mutants with the recently described 2-aa insertions between codons 68 and 70 of RT were detected in another 3 patients. Among the four isolates with the 1- or 2-aa insertions, the novel genotype was the most refractory to therapy and displayed the highest level of phenotypic resistance to nucleoside reverse transcriptase inhibitors (NRTIs). Follow-up samples demonstrated that the novel mutant represents a stable genetic rearrangement and that the amino acid insertions can coexist with nonnucleoside analogue reverse transcriptase inhibitors (NNRTI) mutations resulting in phenotypic resistance to both NRTIs and NNRTIs. An increasing number of HIV-1 isolates containing various insertions in the beta3-beta4 hairpin of the HIV-1 RT fingers subdomain appear to emerge after prolonged therapy with different NRTIs, and these polymorphisms can confer multiple drug resistance against NRTIs.

Amino Acid Substitution↗

Controlled-release misoprostol vaginal insert in parous women for labor induction: a randomized controlled trial.

OBJECTIVE: To assess the ability of a controlled-release misoprostol vaginal insert to induce labor using dose reservoirs of 25, 50, 100, and 200 microg. METHODS: This double-blind, dose ranging, randomized study was carried out in parous women requiring induction of labor at term. Each woman was randomly assigned to receive a single misoprostol vaginal insert that could remain in place for up to 24 hours and was removed for onset of active labor, an adverse event, or having reached 24 hours in situ. The primary outcome measure was time from insertion of the misoprostol vaginal insert to vaginal delivery of the neonate. RESULTS: A total of 124 women participated in the study. The median time to vaginal delivery was 27.5, 19.1, 13.1, and 10.6 hours for the 25-, 50-, 100-, and 200-microg doses, respectively. The percentage of women who delivered vaginally within 12 hours was 9%, 14%, 47%, and 53% (P<.001 using the 25-microg group as the comparator) and within 24 hours was 42%, 79%, 81%, and 70% (P=.003). Uterine hyperstimulation syndrome occurred in one woman who received the 25-mug, two women who received the 100-microg, and three women who received the 200-microg dose reservoirs. CONCLUSION: Misoprostol vaginal inserts effectively induced labor in pregnant parous women at term. LEVEL OF EVIDENCE: I.

Administration, Intravaginal↗

Metrology to quantify wear and creep of polyethylene tibial knee inserts.

Assessment of damage on articular surfaces of ultrahigh molecular weight polyethylene tibial knee inserts primarily has been limited to qualitative methods, such as visual observation and classification of features such as pitting, delamination, and subsurface cracking. Semiquantitative methods also have been proposed to determine the linear penetration and volume of the scar that forms on articular surfaces of tibial knee inserts. The current authors report a new metrologic method that uses a coordinate measuring machine to quantify the dimensions of this scar. The articular surface of the insert is digitized with the coordinate measuring machine before and after regular intervals of testing on a knee simulator. The volume and linear penetration of the scar are calculated by mathematically taking the difference between the digitized surface maps of the worn and unworn articular surfaces. Three conventional polyethylene tibial knee inserts of a posterior cruciate-sparing design were subjected to five million cycles of normal gait on a displacement-driven knee wear simulator in bovine serum. A metrologic method was used to calculate creep and wear contributions to the scar formation on each tibial plateau. Weight loss of the inserts was determined gravimetrically with the appropriate correction for fluid absorption. The total average wear volume was 43 +/- 9 and 41 +/- 4 mm3 measured by the metrologic and gravimetric methods, respectively. The wear rate averaged 8.3 +/- 0.9 and 8.5 +/- 1.6 mm3 per million cycles measured by the metrologic and gravimetric methods, respectively. These comparisons reflected strong agreement between the metrologic and gravimetric methods.

Equipment Failure Analysis↗

Backside wear of Miller-Galante I and Insall-Burstein II tibial inserts.

The objective of this study was to determine if there was a difference in the amount, type, and location of backside wear in the Miller-Galante I and Insall-Burstein II PE tibial inserts. A secondary objective was to determine if backside wear damage in these two designs was a function of clinical factors (patient height, weight, gender, age, and length of time of implantation), shelf life of the PE tibial insert, and tibial component thickness. Backside wear damage was assessed on 24 Miller-Galante I and 11 Insall-Burstein II tibial inserts (implantation time, 0.5-12.4 years). For both groups combined, implantation time was positively correlated to wear damage and to PE peg height into screw holes. The Miller-Galante I group had significantly larger PE pegs than the Insall-Burstein II group. The Miller-Galante I group had significantly more burnishing and larger PE pegs posteriorly than anteriorly. There was no correlation between insert shelf life before initial surgery and backside wear. The thinner the component, the larger the total damage scores in the Miller-Galante I group. This study supports the hypothesis that backside wear of PE tibial inserts may be influenced by design and component thickness and by clinical factors.

Humans↗

Trochanteric nail insertion for the treatment of femoral shaft fractures.

OBJECTIVES: This study was designed to evaluate whether the use of a new femoral nail, specifically designed to be inserted through the greater trochanter, could eliminate the complications previously seen with insertion of straight nails through this entry portal for the treatment of femoral shaft fractures. DESIGN: Prospective, clinical trial. SETTING: Three level I trauma centers. PATIENTS: Sixty-one consecutive patients with femoral shaft fractures (50 closed and 11 open fractures) treated with antegrade nailing with insertion through the greater trochanter. INTERVENTION: All patients were treated in the supine position with a TAN nail (Trigen System, Smith & Nephew, Memphis, TN) inserted through the greater trochanter. MAIN OUTCOME MEASURE: Union, alignment, complications, and hip function. RESULTS: Forty-six of 57 (81%) surviving patients were available for follow-up at a minimum of 12 (range, 12-25) months. Union occurred in all but 1 fracture after the index procedure. No patient sustained iatrogenic fracture comminution, and there were no angular malunions. Pain was reported as slight in 6 patients and moderate in 2. Visual and videotaped gate analysis, performed on 24 patients, revealed symmetrical walking in 21. CONCLUSIONS: This study demonstrates that antegrade nailing of femoral shaft fractures with a specially designed nail inserted through a trochanteric starting point provides predictably high union rates and low rates of complications. Ease of entry and utility in patients with a large body habitus are advantages over conventional piriformis fossa entry techniques. Nailing through the greater trochanter with the patient supine is presently our treatment of choice for patients with femoral shaft fractures.

Adolescent↗

Incidence and management of encapsulated cysts following Ahmed glaucoma valve insertion.

PURPOSE: Encapsulated cysts have been inconsistently reported to occur following Ahmed glaucoma valve implant insertion. We are unaware of previous reports reviewing their management. The objective of this study was to evaluate the occurrence and management of encapsulated cyst formation following Ahmed glaucoma valve implant insertion. PATIENTS AND METHODS: Consecutive glaucoma patients who underwent Ahmed glaucoma valve implant insertion were studied retrospectively. Inclusion criteria included a minimum of 12 months of follow-up. RESULTS: Fifty-seven patients met inclusion criteria for analysis. Following Ahmed glaucoma valve implant insertion, 13 patients (23%) developed an encapsulated cyst. After failing medical therapy and needling with 5-fluorouracil, 11 of these patients underwent surgical excision to control intraocular pressure. Eight of the eleven patients achieved adequate control of intraocular pressure with a mean follow-up time post excision of 330 +/- 120 days. CONCLUSION: Encapsulated cysts associated with elevated intraocular pressure were commonly seen after Ahmed glaucoma valve implant insertion. Failing medical therapy, surgical excision of the cyst is effective in lowering intraocular pressure.

Adolescent↗

Computer-assisted versus conventional surgery for insertion of 96 cannulated iliosacral screws in patients with postpartum pelvic pain.

BACKGROUND: The purpose of this study was to assess the value of fluoroscopy-based computer-assisted surgery (CAS) for the insertion of iliosacral screws. The results of CAS were compared with the results of a conventionally operated prospective control group. Endpoints of this study were fluoroscopy time, guide wire insertion time, operation time and complication rate. METHODS: The study group consisted of 24 patients with postpartum pelvic pain syndrome. All patients were treated with a stabilization of the pelvic ring by means of an anterior plate fixation and autologous tricortical bone graft as well as two iliosacral screws bilaterally. Consequently, the results of 48 versus 48 iliosacral screw fixations could be evaluated. Conventionally operated patients were turned from the supine to the prone position intraoperatively, whereas CAS operated patients were operated in the supine position. One surgeon performed all operations. RESULTS: The fluoroscopy time in the CAS group was 0.7 minutes versus 1.8 minutes in the conventionally treated group (p < 0.01). The mean insertion time for four guide wires was 20.2 minutes in the CAS versus 19.4 minutes in the conventionally operated group (p = 0.6). The mean operation time in the CAS group was 97 minutes; 116 minutes in the conventional group (p = 0.03). In the CAS group one patient had pain and a sensory deficit of S2 postoperatively. The Fisher's exact test showed no difference in complication rate between the two groups (p = 0.26). CONCLUSIONS: The fluoroscopy time is decreased with a factor 2.5 using CAS. Guide wire insertion time was similar in both groups. The reduction in operation time using CAS was due to fact that patients were operated in the supine position during the whole procedure. This study shows that CAS is a save technique for insertion of iliosacral screws.

Adult↗

On the structure, genesis and significance of DNA duplications at the Rous sarcoma proviral insertion sites in Rat-1 cells.

We have previously shown that most Rous sarcoma proviruses in Rat-1 cells are simple insertions, at apparently random sites, and are not transcribed. A small minority of simple insertions are transcribed and these show a bias to insertion at sites closely 3' to presumptive cellular CG-rich islands. However, most transcribed proviruses are complex, typified by contiguous duplications of proviral DNA 5' to a complete proviral unit. The cellular sites of these complex insertions are unknown and their structure and significance incompletely documented. We report here more extensive analyses of proviral duplications, with the following findings. The 5' duplications predominantly involve proviral regions known to contain enhancer functions, substantiating earlier data. The cellular insertion sites are not biased to CG-rich loci at the level displayed by simple transcribed proviruses. The detailed structure of two duplications, and partial analysis of several others, strongly favours their genesis by illegitimate template transfer at reverse transcription, followed by self-recombination. These findings show that aberrant reverse transcription can generate duplications that dispense with the need for an expressed provirus to be integrated at a favourable cellular site.

Animals↗