Computer assisted implantation of the femoral stem in THA – an experimental study

Fourteen femoral stems were implanted either manually by an experienced surgeon or by a robot in fresh human cadaveric femora. The neck-shaft angle, the anteversion, the length of the femoral neck and the gap between stem and bone was measured in each specimen. Implantation by robot showed higher precision in reconstructing the true anatomic situation as well as providing a better press fit.     

Errors of computer-assisted migration analysis in conventional radiographs of femoral hip implants – an experimental study

Several methods have been described in the literature in order to analyze migration of femoral hip implants in conventional radiographs. However, no measurements were done regarding the potential errors inherent in such unstandardized radiographs of daily routine. In order to quantify this lack of reproducibility, we carried out experimental examinations with radiographs of a hip revision prosthesis, where different variables of technical X-ray conditions and femoral positions were changed. All radiographs were analyzed with a computer-assisted processing system by different procedures. At first, the radiographs were calibrated geometrically. Then, particular reference distances between defined points of the implant and cortical bone structures were analyzed quantitatively. The error of the axial migration analysis was up to 11.11 mm concerning different femoral positions, up to 8.29 mm in the case of different source-to-film distances and up to 2.21 mm due to different lateral localizations of the central X-ray focus. Significant errors for the migration analysis in the transverse and rotational planes were only found under conditions of varying the femoral position, and not under different technical X-ray conditions. From these experimental results, we derived the following criteria to minimize failure in a quantitative radiographic migration analysis: (1) the patient’s leg has to be placed into an antirotation device to ensure identical object position; (2) the same source-to-film distance has to be used; (3) the central X-ray focus has to be localized on the center of the film-cassette; (4) film-screen systems should be of the same type and size; (5) the object has to be placed in the same position as in previous radiographs. As a conclusion, only if these standardization criteria are respected in the daily routine of conventional radiographs will an effective and meaningful use of migration analysis systems be possible to prove or to exclude mechanical failure of femoral hip implants in prospective longitudinal follow-up series. Received: 19 May 1998     

Comparison of two different transection techniques in liver surgery—an experimental study in a porcine model

Aims

Postoperative morbidity and mortality after liver resection is closely related to the degree of intraoperative blood loss; the majority of which occurs during transection of the liver parenchyma. Many approaches and devices have therefore been developed to limit bleeding, but none has yet achieved perfect results up to now. The aim of this standardized chronic animal study was to compare the safety and efficacy of the LigaSure? Vessel Sealing System (LVSS) with the stapler technique, which is one of the modern techniques for transecting the parenchyma in liver surgery.

Methods

Sixteen pigs underwent a left liver resection (LLR). Eight pigs received a LLR by means of an Endo GIA, whereas the other eight pigs underwent liver parenchymal transection followed by simultaneous sealing by the LVSS. The operating time, transection time, blood loss during transection, and time of hemostasis were measured on the day of LLR (postoperative day 0/POD 0). Animals were re-explored on postoperative day 7 (POD 7) and the transection surface of remnant liver was observed for fluid collection (hematoma, biloma, and abscess), necrosis, and other pathologies. A biopsy was taken from the area of transection for histopathological examination.

Results

All animals survived until POD 7. Operating time and transection time of the liver parenchyma on POD 0 was significantly shorter in the stapler group. There was no significant difference between the two groups in terms of blood loss during transection, time of hemostasis and number of sutures for hemostasis on POD 0, morbidity rate, as well as the histopathological examination on POD 7. Furthermore, the material costs were significantly higher in the stapler group than in the LVSS group.

Conclusion

In this standardized chronic animal study concerning transection of the parenchyma in liver surgery, LVSS seems not only to be safe, but also comparable with the stapler technique in terms of morbidity and mortality. Additionally, LVSS significantly reduces material costs. However, the transection time is significantly longer for LVSS than for the stapler resection technique.     

Cefuroxime concentrations in the anterior and posterior column of the lumbar spine – an experimental porcine study

BACKGROUND CONTEXTSurgical site infection following spine surgery is associated with increased morbidity and mortality. Perioperative antibiotic prophylaxis is a key factor in lowering the risk of acquiring an infection. Previous studies have assessed perioperative cefuroxime concentrations in the anterior column of the cervical spine with an anterior surgical approach. However, the majority of surgeries are performed in the posterior column and many surgeries involve the lumbar spine.PURPOSEThe objective of this study was to compare the perioperative tissue concentrations of cefuroxime in the anterior and posterior column during lumbar spine surgery with a posterior surgical approach.STUDY DESIGNIn vivo experimental pharmacokinetic study of cefuroxime concentrations in an acute preclinical porcine model.METHODSThe lumbar vertebral column was exposed from L1 to L5 in 8 female pigs. Microdialysis catheters were placed for sampling in the anterior column (vertebral body) and posterior column (posterior arch) within the same vertebra (L5). Cefuroxime (1.5 g) was administered intravenously. Microdialysates and plasma samples were continuously obtained over 8 hours. Cefuroxime concentrations were quantified by Ultra High Performance Liquid Chromatography Tandem Mass Spectrometry. The primary endpoint was the time above the cefuroxime clinical breakpoint minimal inhibitory concentration (T>MIC) for Staphylococcus aureus of 4 µg/mL. The secondary endpoint was tissue penetration (AUC_tissue/AUC_plasma).RESULTSMean T>MIC 4 µg/mL (95% confidence interval) was 123 min (105–141) in plasma, 97 min (79–115) in the anterior column and 93 min (75–111) in the posterior column. Tissue penetration (95% confidence interval) was incomplete for both the anterior column 0.48 (0.40–0.56) and posterior column 0.40 (0.33–0.48).CONCLUSIONST>MIC was comparable between the anterior and posterior column. Mean cefuroxime concentrations decreased below the clinical breakpoint minimal inhibitory concentration for S. aureus of 4 µg/mL after 123 minutes (plasma), 97 minutes (anterior column) and 93 minutes (posterior column). This is shorter than the duration of most lumbar spine surgeries, and therefore alternative dosing regimens should be considered in posterior open lumbar spine surgeries lasting more than 1.5 hours.CLINICAL SIGNIFICANCEOpen lumbar spine surgery often involves extensive soft tissue dissection, stripping and retraction of the paraspinal muscles which may impair the local blood flow exposing the lumbar vertebra to postoperative infections. A single intravenous administration of 1.5 g cefuroxime only provided sufficient prophylactic target tissue concentrations in the vertebra of the lumbar spine for up to 1.5 hours.     

Minimally invasive plate osteosynthesis: does percutaneous plating disrupt femoral blood supply less than the traditional technique?

OBJECTIVES/HYPOTHESIS: Proximal and distal femur fractures have traditionally been treated with open reduction and internal fixation through a standard lateral approach. New, "minimally invasive" internal fixation techniques, however, have been developed in an effort to devascularize the bone less than the traditional method. The purpose of this study was to determine whether a minimally invasive percutaneous plating technique better preserves bone vascularity relative to the traditional method by comparing the effect of the two approaches on the blood supply of the distal femur using silicone arterial dye injection in a cadaveric model. STUDY DESIGN/METHODS: Ten fresh human cadavers underwent lateral conventional plate osteosynthesis (CPO) through a standard lateral approach on one side and minimally invasive plate osteosynthesis (MIPO) through two three-centimeter incisions on the contralateral side. After injection of silicone dye, a dissection was performed bilaterally to identify the femoral perforating and nutrient arteries. RESULTS: All MIPO specimens showed intact perforating and nutrient arteries, whereas the CPO specimens had a variable incidence of vessel disruption. The MIPO group demonstrated better periosteal perfusion in each of the cadavers and improved medullary perfusion in 70 percent of the MIPO specimens compared with the CPO specimens. CONCLUSION: A percutaneous minimally invasive plating technique disrupts the femoral blood supply less than the traditional open method. Such minimally invasive methods may be more advantageous biologically than the traditional method.     

Bridge tendon graft in no man‘s land:an experimental study in chickens

Objective:To investigate the morphological characteristics of the bridge tendon grafting in no man‘s land to reconstruct the tendon defect and the effect of passive mobilization on it.Methods:A 2 cm defect was made in bilateral flexor digitorum profundus tendons of the middle chicken toes,and was then transplanted to the opposite site to serve as a segmental autograft tendon.Postoperatively,passive mobilization of the left and right middle toes began at 5 and 21 d separately.Specimens were studied by light,scanning and transmission electron microscopy at 5,10,21 and 35d.Results:Early repair of the tendon-graft of the left middle toes was made by proliferation and ingrowth of the epitenon cells intermingled with newly-formed collagen fibers.a gliding surface formed at 10 and 21 d.The tendon graft itself played an active role in the repair.In contrast,adhesions obliterated the surface and occupied the space between the tendon graft and surrounding tissues in the right middle toes.Conclusions:It indicates that the use of the segmental bridge tendon graft in no man‘s land coupled with early passive motion stimulates an intrisic repair process in both the tendon stump and the autogenous tendon graft and results in a functional healing.     

Posttraumatic expression of MHC Ⅱ molecules: an experimental and clinical study

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Study of the response of the urinary bladder to stimulation of the cervix uteri and clitoris — The ‘genitovesical reflex’: An experimental study

There is a debate as to whether, during the sexual act, some women eject a fluid that could be urine. As a part of investigation into this subject, the effect of stimulation of the clitoris and cervix on urinary bladder pressure and external urethral sphincter (EUS) activity was studied in 12 bitches. The clitoris and cervix were stimulated both electrically and mechanically. Upon clitoral or cervical stimulation, the vesical pressure dropped (P<0.05) and the EMG activity of EUS increased; action potentials increased and latency decreased when the stimulation frequency increased. No fluid came out of the external urethral orifice or the vagina. Stimulation of the anesthetized clitoris and cervix effected no vesical pressure or EUS response. These results were reproducible. The study has shown that on clitoral and cervical stimulation, which closely simulates the conditions during coitus, the bladder neck was firmly closed by EUS contraction, whereas the vesical detrusor was relaxed. A constant and reproducible reflex relationship existed between the clitoris, or the cervix, and the urinary bladder, which the author calls the genitovesical reflex and which probably acts to prevent urinary leak during coitus. The genitovesical reflex may prove to be of diagnostic significance in genitourinary disorders.Editorial Comment: This is a very interesting study on the effects of clitoral and cervical stimulation on the bladder and external urethral sphincter. It points out that in the normal female dog (and possibly in the normal female patient) cervical and clitoral stimulation, as might occur with coitus, should bring about relaxation of the bladder and an increase in the tone of the external urethral sphincter to prevent urine loss. I think this points out that urine loss associated with orgasm should be considered pathologic, and may be a symptom of detrusor instability. The pathologic association of urinary incontinence with orgasm and detrusor instability was pointed out by Hilton in 1988 and Khan in 1988. This paper complements these studies by demonstrating a reflex in the female dog which produces bladder relaxation and external urethral sphincter tone increase during coital-type stimulation.     

Androgen receptors and experimental bone loss — an in vivo and in vitro study

Testosterone is a sex hormone that exhibits many functions beyond reproduction; one such function is the regulation of bone metabolism. The role played by androgen receptors during testosterone-mediated biological processes associated with bone metabolism is largely unknown. This study aims to use a periodontal disease model in vivo in order to assess the involvement of androgen receptors on microbial-induced inflammation and alveolar bone resorption in experimental bone loss. The impact of hormone deprivation was tested through both orchiectomy and chemical blockage of androgen receptor using flutamide (FLU). Additionally, the direct effect of exogenous testosterone, and the role of the androgen receptor, on osteoclastogenesis were investigated. Thirty male adult rats (n = 10/group) were subjected to: 1-orchiectomy (OCX); 2-OCX sham surgery; or 3-OCX sham surgery plus FLU, four weeks before the induction of experimental bone loss. Ten OCX sham-operated rats were not subjected to experimental bone loss and served as healthy controls. The rats were euthanized two weeks later, so as to assess bone resorption and the production of inflammatory cytokines in the gingival tissue and serum. In order to study the in vitro impact of testosterone, osteoclasts were differentiated from RAW264.7 cells and testosterone was added at increasing concentrations. Both OCX and FLU increased bone resorption, but OCX alone was observed to increase osteoclast count. IL-1β production was increased only in the gingival tissue of OCX animals, whereas FLU-treated animals presented a decreased expression of IL-6. Testosterone reduced the osteoclast formation in a dose-dependent manner, and significantly impacted the production of TNF-α; FLU partially reversed these actions. When taken together, our results indicate that testosterone modulates experimental bone loss, and that this action is mediated, at least in part, via the androgen receptor.     

Biomechanical study on the suture strength of ligament in cruciate ligament reconstruction

Objective: To test the suture strength on the tendon or ligament end and evaluate the stitch in the reconstruction of cruciate ligament and its clinical application. Methods: Twenty-four specimens of patellar tendon with free ends were divided into 3 groups: Group I (3 Krackow stitches ), Group H ( 2 Krackow stitches ) and Group HI (2 Krackow stitches with the first stitch passing through the tendon tissue as a modified Krackow stitch).These 3 groups were further divided into 6 subgroups according to different suture materials, No 1 Ethilon or stainless steel wire (φ = 0.4 mm ). Tensile test was undertaken to f‘md out the least stitches with efficient suture pattern. Results: Two Krackow locking stitches had stronger strength than 0.4 mm-diameter stainless steel wire. The fixation strength of 2 stitches with No 1 Ethilon was more than 80 N, superior to the failure strength of the material itself. The same strength was maintained if the first stitch was across the tendon tissue transversely. There was no statistically significant difference in the suture strength between 2 and 3 Krackow locking stitches. Conclusions: The suture strength is greater than the failure strength of the suture material. Less suture exposure can be achieved when the first stitch is across the tendon tissue while maintaining a comparable strength to other sutures. To attain higher suture strength, stronger materials or multiple strands rather than more stitches are preferred. Therefore, a rapid early rehabilitation of range of motion (ROM) is possible and reliable in practice.     

Biomechanical and anatomical considerations in lumbar spinous process fixation—an in vitro human cadaveric model

Background contextAlthough multiple mechanisms of device attachment to the spinous processes exist, there is a paucity of data regarding lumbar spinous process morphology and peak failure loads.PurposeUsing an in vitro human cadaveric spine model, the primary objective of the present study was to compare the peak load and mechanisms of lumbar spinous process failure with variation in spinous process hole location and pullout direction. A secondary objective was to provide an in-depth characterization of spinous process morphology.Study designBiomechanical and anatomical considerations in lumbar spinous process fixation using an in vitro human cadaveric model.MethodsA total of 12 intact lumbar spines were used in the current investigation. The vertebral segments (L1–L5) were randomly assigned to one of five treatment groups with variation in spinous process hole placement and pullout direction: (1) central hole placement with superior pullout (n=10), (2) central hole placement with inferior pullout (n=10), (3) inferior hole placement with inferior pullout (n=10), (4) superior hole placement with superior pullout (n=10), and (5) intact spinous process with superior pullout (n=14). A 4-mm diameter pin was placed through the hole followed by pullout testing using a material testing system. As well, the bone mineral density (BMD) (g/cm³) was measured for each segment. Data were quantified in terms of anatomical dimensions (mm), peak failure loads (newtons [N]), and fracture mechanisms, with linear regression analysis to identify relationships between anatomical and biomechanical data.ResultsBased on anatomical comparisons, there were significant differences between the anteroposterior and cephalocaudal dimensions of the L5 spinous process versus L1–L4 (p<.05). Statistical analysis of peak load at failure of the four reconstruction treatments and intact condition demonstrated no significant differences between treatments (range, 350–500 N) (p>.05). However, a significant linear correlation was observed between peak failure load and anteroposterior and cephalocaudal dimensions (p<.05). Correlation between BMD and peak spinous processes failure load was approaching statistical significance (p=.08). 30 of 54 specimens failed via direct pullout (plow through), whereas 8 of 54 specimens demonstrated spinous process fracture. The remaining cases failed via plow through followed by fracture of the spinous process (16 of 54; 29%).ConclusionsThe present study demonstrated that variation in spinous process hole placement did not significantly influence failure load. However, there was a strong linear correlation between peak failure load and the anteroposterior and cephalocaudal anatomical dimensions. From a clinical standpoint, the findings of the present study indicate that attachment through the spinous process provides a viable alternative to attachment around the spinous processes. In addition, the anatomical dimensions of the lumbar spinous processes have a greater influence on biomechanical fixation than either hole location or BMD.     

The effects of piroxicam to the muscosal barrier of the bladder after overdistension – an experimental study in rabbits

The effects of piroxicam on the duration and severity of damage to the mucosal barrier of the urinary bladder after overdistension was investigated.Overdistension of the bladder was induced for 3 h in 16 New Zealand male rabbits by giving Ringer's lactate infusion (40 ml/kg/h) and furosemide (1 mg/kg) to the peritoneal cavity. Insertion of 8 Fr Foley catheter was used for obstruction of the bladder neck. In both control (C) and piroxicam (P) groups, 20 mL of 2% solution of Trypan blue in 0.9% NaCl solution was instilled into the bladder for 1 hr at 0, 24, 48 h and 7 days after overdistension. In group P daily intramuscular injection of 5 mg/kg piroxicam, and isotonic saline in group C was administrated for 7 days. Full-thickness samples were taken from the bladder at 0, 24, 48 h and 7 days after overdistension. The bladder wall was deep blue throughout in both groups at 0, 24, and 48 h. The severity and duration of inflammatory reaction was lower and nearly normalized on the 7th post procedure day in piroxicam group.Conclusion: Inflammatory reaction can be prevented by administration of anti-inflammatory drugs such as piroxicam but the prevention of increased permeability is unclear after overdistension of the bladder.     

Bridging and non‐bridging external fixation in the treatment of unstable fractures of the distal radius: A retrospective study of 588 patients

Background and purpose?Bridging external fixation is used more frequently than non‐bridging fixation in the management of unstable distal radius fractures, despite evidence from randomized controlled trials of better outcome with the latter technique. This study was designed to investigate the generalizability of the technique of non‐bridging external fixation, and to define the indications for the use of each technique and their complications.

Methods?641 patients with unstable displaced fractures of the distal radius were treated with bridging or non‐bridging external fixation. Non‐bridging external fixation was used where there was space for pins in the distal fragment. 52 patients were lost to follow‐up, leaving 588 patients available for study. Complete data from radiographic measurements after fracture healing were available for 546 patients. 59 % of fractures were treated with the non‐bridging technique.

Results?Fractures treated with bridging external fixation had a 6 times increased risk of dorsal malunion (p < 0.001) and a 2.5 times increased risk of radial shortening (p < 0.001) after adjusting for confounding factors (95% CI for odds ratio: 3–13 and 1.5–4, respectively) compared to non‐bridging techniques. Minor pin tract infections were more common in the non‐bridging group.

Interpretation?Non‐bridging external fixation of the distal radius is a generalizable technique, and reduces the risk of dorsal malunion compared with bridging external fixation. Major complication rates are low and the technique is applicable to most unstable fractures of the distal radius. We recommend that non‐bridging external fixation be used where there is space for the pins in the distal fragment.     

Core decompression in early stages of femoral head osteonecrosis – an MRI-controlled study

We treated 45 hips with idiopathic necrosis of the femoral head stages I-III with core decompression. Average age of patients was 41 (27-68) years and average follow-up 68.9 (31-120) months. In 30 hip joints in stage I, 29 showed no radiographic progression and a complete remission of the changes consistent with necrosis on MRI at the last follow-up. In 27 patients the clinical result based on the Harris Hip Score (HHS) assessment--was excellent (average HHS 91.9 points). Of nine hips in stage II, four had received a total hip arthroplasty, one had deteriorated to stage IV, and four were still classified as stage II (average HHS 95 points). Of six hips in stage III, three had received a total hip arthroplasty and three had deteriorated to stage IV (average HHS 73 points).     

The role of occlusion and micro-incontinence in the pathogenesis of penile lichen sclerosus: an observational study of pro-inflammatory cytokines’ gene expression

Purpose

To assess the expression of selected cytokines in penile lichen sclerosus (PLS) and associate them with the occurrence of micro-incontinence (MI) in different stages of PLS.

Methods

The skin biopsies from 49 PLS affected, and 13 from nonlesional foreskins (healthy control adult males undergoing circumcision due to phimosis caused by short frenulum) were obtained. All specimens were used for RNA extraction and RT-qPCR. Quantitative assessment of the gene expression of interleukin 1-A (IL-1A), interleukin 1-B (IL-1B), interleukin 1 receptor antagonist (IL-1RN), interleukin 6 (IL-6), transforming growth factor β1 (TGF-β1), and interferon-gamma (INF-γ) was performed. To determinate the presence of MI, the patients were asked about voiding patterns, especially leaking tiny drops of urine from the urethral meatus after urination.

Results

IL-1A, IL-6, and INF-γ mRNA levels were approximately 150, 16, and 59 times higher in PLS than in control samples, respectively. The highest IL-1A mRNA levels were observed in early PLS (n?=?13), INF-γ in moderate PLS (n?=?32), while IL-6 in severe PLS (n?=?4). MI was noted in 45 PLS patients vs. 0 in control (p?<?0.0001). IL-1A and IL-6 vs control ratios were concentration (ca.) 400 and 30 times higher, respectively, in MI PLS samples than in PLS without MI.

Conclusion

Occlusion and irritating urine effect are associated with the clinical progression of penile LS with increased mRNA expression of IL-1A, INF-γ, and IL-6 pro-inflammatory cytokines in the foreskin.

     

Non-union and use of proton pump inhibitors in the treatment of femoral and tibial shaft fractures: a nested case–control study

European Journal of Orthopaedic Surgery & Traumatology - Proton pump inhibitors (PPIs) are one of the most frequently used drugs worldwide. Previous research has shown that they could increase...