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.     

A quantitative anatomic study of plate–screw fixation of the acetabular anterior column through an anterior approach

Background  

Screw penetration of the hip joint is a serious complication during plate–screw internal fixation of acetabular anterior column or anterior wall fractures through an anterior approach. The purpose of the cadaveric study is to determine safe paths for screw placement on the anterior column of the acetabulum.     

How do anterior/posterior translations of the thoracic cage affect the sagittal lumbar spine,pelvic tilt,and thoracic kyphosis?

Anterior and posterior thoracic cage translations in the sagittal plane have not been reported for their range of motion and effects on the lumbar spine and pelvis. Twenty subjects volunteered for full-spine radiography in neutral, anterior, and posterior thoracic cage translation postures in a standing position. While grasping an anterior vertical pole, with hands at elbow level, subjects were instructed on how to translate their thoracic cage without any flexion/extension, utilizing a full-length mirror. On the radiographs, all four vertebral body corners of T1 through S1 and the superior margin of the acetabulum were digitized. Segmental and global angles of thoracic kyphosis, sagittal lumbar curvature, and pelvic flexion/extension in translation postures were compared to alignment in the neutral posture. Using the femur heads as an origin, the mean range of thoracic cage translation, measured as horizontal movement of T12 from neutral posture, was found to be 85.1 mm anterior and 73 mm posterior. In anterior translation, the thoracic kyphosis is hypokyphotic (Cobb T1-T12 reduced by 16 degrees). In posterior translation, the segmental angles at T12-L1 and L1-L2 flexed, creating an "S" shape in the sagittal lumbar spine, while the thoracic kyphosis increased by 10 degrees. Using posterior tangents from L1 to L5 and T12 to S1, and Cobb angles at T12-S1, the lumbar curve reduced slightly (by less than 3.3 degrees for all global angle measurements) in anterior translation and reduced by 7.4 degrees, 5.7 degrees, and 8.1 degrees respectively in posterior thoracic translation. The angle of pelvic tilt (measured as the angle of intersection of a line through posterior-inferior S1 to the superior acetabulum and the horizontal) reduced by a mean of 15.9 degrees, and Ferguson's sacral base angle to horizontal reduced by a mean of 13.1 degrees in posterior translation. In anterior translation, pelvic tilt and Ferguson's sacral base angle increased by 15.1 degrees and 12.8 degrees, respectively. The findings of this study show that thoracic cage anterior/posterior translations cause significant changes in thoracic kyphosis (26 degrees ), lumbar curve, and pelvic tilt. An understanding of this main motion and consequent coupled movements might aid the understanding of spinal injury kinematics and spinal displacement analysis on full spine lateral radiographs of low back pain and spinal disorder populations.     

Alendronate treatment improves bone–pedicle screw interface fixation in posterior lateral spine fusion: An experimental study in a porcine model

The bone–screw interface has been indicated as the weak link in pedicle screw spine fixation. Bisphosphonate treatment may have the effect of improving bone–screw interface fixation in spine fusion by inhibiting bone resorption. An experimental study was conducted using a porcine model to evaluate the influence of alendronate treatment on bone–pedicle screw interface fixation. Eleven pigs in the treatment group received alendronate 10 mg/day orally for three months postoperatively. The other 11 pigs served as a control group. Posterior lateral fusion with the CD Horizon pedicle screw system was performed with autograft on the lumbar spine on all animals. Biomechanical torsion test and histomorphometric parameters of screw fixation were evaluated three months after the operation. The maximum torque and initial angular stiffness of the treatment group was higher than that of the control group, but there was no statistical significance. The bone–screw contact surface was 23.3 ± 10% for the treatment group and 9.8 ± 5.9% for the control group (P < 0.01). This study indicated that alendronate treatment increased bone purchase of stainless steel screw surfaces.     

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.     

Does the choice of suture material matter in anterior and posterior colporrhaphy?

Introduction and hypothesis

The optimal suture material in traditional prolapse surgery is still controversial. Our aim was to investigate the effect of using sutures with rapid (RA) or slow (SA) absorption, on symptomatic recurrence after anterior and posterior colporrhaphy.

Methods

A population-based longitudinal cohort study with data from the Swedish National Quality Register for Gynecological Surgery. A total of 1,107 women who underwent primary anterior colporrhaphy and 577 women who underwent primary posterior colporrhaphy between September 2012 and September 2013 were included. Two groups in each cohort were created based on which suture material was used. Pre- and postoperative prolapse-related symptoms and patient satisfaction were assessed.

Results

We found a significantly lower rate of symptomatic recurrence 1 year after anterior colporrhaphy in the SA suture group compared with the RA suture group, 50 out of 230 (22 %) vs 152 out of 501 (30 %), odds ratio 1.6 (CI 1.1–2.3; p?=?0.01). The SA group also had a significantly higher patient satisfaction rate, 83 % vs 75 %, odds ratio 1.6 (CI 1.04–2.4), (p?=?0.03). Urgency improved significantly more in the RA suture group (p?<?0.001). In the posterior colporrhaphy cohort there was no significant difference between the suture materials.

Conclusions

This study indicates that the use of slowly absorbable sutures decreases the odds of having a symptomatic recurrence after an anterior colporrhaphy compared with the use of rapidly absorbable sutures. However, the use of RA sutures may result in less urgency 1 year postoperatively. In posterior colporrhaphy the choice of suture material does not affect postoperative symptoms.

     

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.     

Incidence of neuroendocrine cells in the seminal vesicles and the prostate – an immunohistochemical study

Introduction: Prostate and seminal vesicles(sv) are both androgen-dependent male sexaccessory glands. The cancer incidence in thesetwo organs is vastly different. Neuroendocrine(NE) cells are involved in the regulation ofprostate growth, differentiation and inprostate cancer carcinogenesis. Thus, knowledgeof the incidence of NE cells in sv may add toour understanding of prostate cancer etiology.Methods: Samples of histologically confirmednormal prostate tissue and normal sv tissuefrom 20 men were immunostained for chromograninA. The incidence of stained cells was evaluatedsemiquantitately.Results: Neuroendocrine cells were detected inall prostate specimens, but not a singlestained cell was found in any of the sv specimens.Conclusions: The lack of NE cells and,subsequently, of biogenic amines, peptides andgrowth factors may be a reason for the lowcancer incidence in the seminal vesicles.Alternatively, the absence of NE cells can beseen as a hint that the stem cells of theprostate and sv react differently to endogenousand exogenous stimuli, and thus in the seminalvesicles, stem cells are not transformed intoNE cells.     

Degenerative disorders of the lumbar spine Total disc replacement as an alternative to lumbar fusion?

Spinal fusion is accepted worldwide as a therapeutic option for the treatment of degenerative disorders of the lumbar spine. Because there are only few evidence-based data available supporting the usefulness of lumbar spinal fusion, its questionable benefit as well as the potential for complications are the reasons for an ongoing discussion.In recent years, total disc replacement with implants has emerged as an alternative treatment. Although early results are promising, there is still a lack of evidence-based data as well as of long-term results for this technology. This article gives a critical update on the implant systems currently in use (SB Charité, Prodisc II L, Maverick, Flexicore, Mobidisc), which all have to be considered as "first-generation" implants. Morphological and clinical sequelae of the different biomechanical properties, designs, and materials have not yet been sufficiently investigated. There is no international consensus on the indication spectrum and on the preoperative diagnosis of discogenic low back pain. The same is true for the (minimally invasive) surgical access strategies. Complication rates seem to be somewhat lower compared to spinal fusion techniques. There are no standardized revision concepts in cases of implant failure.Lumbar disc replacement has opened a new era in spinal surgery with a still unproven benefit for the patient. It is strongly recommended that these techniques should only be applied by experienced and well-trained spine surgeons. Until evidence-based data are available, all patients should be treated under scientific study conditions with close postoperative follow-up.     

Does obesity impact lumbar sagittal alignment and clinical outcomes after a posterior lumbar spine fusion?

European Spine Journal - The purpose of this study is to compare clinical patient-reported outcomes and radiographic sagittal parameters between obese and non-obese patients following open...     

Lateral lumbar interbody fusion in adult spine deformity – A review of literature

IntroductionSurgery for adult spine deformity presents a challenging issue for spinal surgeons with high morbidity rates reported in the literature. The minimally invasive lateral approach aims at reducing these complications while maintaining similar outcomes as associated with open spinal surgeries. The aim of this paper is to review the literature on the use of lateral lumbar interbody fusion in the cases of adult spinal deformity.MethodsA literature review was done using the healthcare database Advanced Research on NICE and NHS website using Medline. Search terms were “XLIF” or “LLIF” or “DLIF” or “lateral lumbar interbody fusion” or “minimal invasive lateral fusion” and “adult spinal deformity” or “spinal deformity”.ResultsA total of 417 studies were considered for the review and 44 studies were shortlisted after going through the selection criteria. The data of 1722 patients and 4057 fusion levels were analysed for this review. The mean age of the patients was 65.18 years with L4/5 being the most common level fused in this review. We found significant improvement in the radiological parameters (lordosis, scoliosis, and disk height) in the pooled data. Transient neurological symptoms and cage subsidence were the two most common complications reported.ConclusionLLIF is a safe and effective approach in managing adult spinal deformity with low morbidity and acceptable complication rates. It can be used alone for lower grades of deformity and as an adjuvant procedure to decrease the magnitude of open surgeries in high-grade deformities.     

Investigating the effects of anterior tibial translation on anterior knee force in the porcine model: Is the porcine knee ACL dependent?

This study sought to determine anterior force in the porcine knee during simulated 6‐degree‐of‐freedom (DOF) motion to establish the role of the anterior cruciate ligament (ACL). Using a 6‐DOF robot, a simulated ovine motion was applied to porcine hind limbs while recording the corresponding forces. Since the porcine knee is more lax than the ovine knee, anterior tibial translations were superimposed on the simulated motion in 2 mm increments from 0 mm to 10 mm to find a condition that would load the ACL. Increments through 8 mm increased anterior knee force, while the 10 mm increment decreased the force. Beyond 4 mm, anterior force increases were non‐linear and less than the increases at 2 and 4 mm, which may indicate early structural damage. At 4 mm, the average anterior force was 76.9 ± 10.6 N (mean ± SEM; p < 0.025). The ACL was the primary restraint, accounting for 80–125% of anterior force throughout the range of motion. These results demonstrate the ACL dependence of the porcine knee for the simulated motion, suggesting this model as a candidate for studying ACL function. With reproducible testing conditions that challenge the ACL, this model could be used in developing and screening possible reconstruction strategies. © 2010 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 29:641–646, 2011     

Role of positioning of femoral component in the anterior–posterior direction on postoperative anterior pain in TKA

European Journal of Orthopaedic Surgery & Traumatology - The patellofemoral joint has proved to be the most problematic element of modern TKA for postoperative anterior knee pain; the...     

Does estrogen alter the mechanical properties of the anterior cruciate ligament? An experimental study in rabbits

BACKGROUND: It is well known that anterior cruciate ligament (ACL) injuries are commoner in female athletes. Accordingly, we hypothesized that serum estrogen may play some role in this sex difference. We evaluated the relationship between serum estrogen levels and the mechanical properties of the ACL in rabbits. ANIMALS AND METHODS: In 40 ovariectomized rabbits, the serum estrogen levels (SEL) were controlled by intramuscular injection of 17beta-estradiol. The mean SEL in each rabbit was defined as the average of 5 determinations done at 1, 2, 3, 4 and 5 weeks after ovariectomy. The animals were divided into 4 groups according to the dose of estradiol administered (low, medium, high and control: L, M, H and C, respectively) and into 2 groups according to the mean SEL (high-SEL group and low-SEL group). The medial portions of ACL attached to both femur and tibia harvested at 5 weeks after ovariectomy were examined mechanically. RESULTS: The mean serum estrogen levels in groups C, L, M and H were 37, 50, 60 and 231 pg/mL. Statistically significant differences in the mean serum estrogen levels were seen among the 4 groups, except between groups L and M. Statistically significant differences were found between groups M and H in both the ultimate tensile stress and linear stiffness. In the comparison between 2 groups using the mean SEL value, both ultimate tensile stress and linear stiffness were lower in the high-SEL group. In all animals, a positive correlation was found between ultimate tensile stress and linear stiffness. INTERPRETATION: Our findings suggest that high SEL might be one of the factors in the multifactorial pathogenesis of ACL rupture.     

Bowel/bladder dysfunction and numbness in the sole of the both feet in lumbar spinal stenosis – A multicenter cross-sectional study

Background

Numbness in the soles of both feet at rest or bowel/bladder dysfunction can occur in patients with lumbar spinal stenosis (LSS), especially in patients with cauda equina lesions. The purpose of this study was to clarify the relationship between cauda equina symptoms at rest and quality of life (QOL) in LSS patients using standardized questionnaires developed for the Japanese population.

Pelvic incidence–lumbar lordosis mismatch results in increased segmental joint loads in the unfused and fused lumbar spine

Purpose

Symptomatic adjacent segment disease (ASD) has been reported to occur in up to 27 % of lumbar fusion patients. A previous study identified patients at risk according to the difference of pelvic incidence and lordosis. Patients with a difference between pelvic incidence and lumbar lordosis >15° have been found to have a 20 times higher risk for ASD. Therefore, it was the aim of the present study to investigate forces acting on the adjacent segment in relation to pelvic incidence–lumbar lordosis (PILL) mismatch as a measure of spino-pelvic alignment using rigid body modeling to decipher the underlying forces as potential contributors to degeneration of the adjacent segment.

Methods

Sagittal configurations of 81 subjects were reconstructed in a musculoskeletal simulation environment. Lumbar spine height was normalized, and body and segmental mass properties were kept constant throughout the population to isolate the effect of sagittal alignment. A uniform forward/backward flexion movement (0°–30°–0°) was simulated for all subjects. Intervertebral joint loads at lumbar level L3–L4 and L4–L5 were determined before and after simulated fusion.

Results

In the unfused state, an approximately linear relationship between sagittal alignment and intervertebral loads could be established (shear: 0° flexion r = 0.36, p < 0.001, 30° flexion r = 0.48, p < 0.001; compression: 0° flexion r = 0.29, p < 0.01, 30° flexion r = 0.40, p < 0.001). Additionally, shear changes during the transition from upright to 30° flexed posture were on average 32 % higher at level L3–L4 and 14 % higher at level L4–L5 in alignments that were clinically observed to be prone to ASD. Simulated fusion affected shear forces at the level L3–L4 by 15 % (L4–L5 fusion) and 23 % (L4–S1 fusion) more for alignments at risk for ASD.

Conclusion

Higher adjacent segment shear forces in alignments at risk for ASD already prior to fusion provide a mechanistic explanation for the clinically observed correlation between PILL mismatch and rate of adjacent segment degeneration.     

Influence of maturity on nucleus–endplate integration in the ovine lumbar spine

Purpose

Recent investigations using an ovine spine model have established that the disc nucleus contains a highly convoluted fibre network with endplate-to-endplate connectivity, this connectivity being achieved via distinctive nodal attachment points. The purpose of this study was to investigate how this nodal anchoring system might be influenced by maturation.

Methods

Lumbar motion segments were dissected from newborn, 3, 12 months and fully mature ovine animals, subjected to a novel annular ring-severing procedure to remove the strain-limiting influence of the annulus, then either mechanically tested to destruction or examined microstructurally and ultrastructurally. The morphology of the nodes and their linear density within the relatively thin section planes were analysed to provide a basis for comparison between the four age groups.

Results

Mechanical testing following ring severing revealed that the remaining nuclear material in all samples, irrespective of maturity, had the ability to transmit a substantial load from endplate to endplate. Imaging of the ring-severed samples from all age groups in their stretched, but unruptured state revealed the presence of axially aligned fibrosity in the nucleus region consistent with endplate-to-endplate connectivity. Endplate insertion nodes were observed in all age groups. Ultrastructural examination revealed that the fibrillar architecture of these nodes in the newborn discs was similar to that observed in the nodes of mature discs. However, there was a rapid increase in their linear density between birth and 3 months, after which this remained constant.

Conclusions

The nodal attachment points identified previously in mature ovine discs are also present in newborn, and 3- and 12-month-old animals with an initial rapid increase in their linear density between birth and 3 months, after which it remained constant. The size and morphology of the attachment points were similar for all ages. Our study suggests that the increase in nodal density in the ovine disc endplate is part of an adaptive response to the loading environment that the disc is exposed to from birth to maturity.     

Do concentrations of neurotransmitters measured in lumbar cerebrospinal fluid reflect the concentrations at brain level?

Summary CSF concentrations of vasoactive intestinal polypeptide (VIP), cholecystokinin (CCK), noradrenaline (NA) and dopamine (DA) were measured in the lateral ventricles and at the lumbar level in patients with normal pressure hydrocephalus (NPH). The concentrations of VIP (n=15), NA (n=10) and DA (n=10) were significantly higher at the lumbar level than at the ventricular level, whereas the concentrations of CCK (n=9) were similar at the two sites. A signifikant positive correlation between the concentrations measured at the two levels was found for VIP (r_s=0.65; p0.01) and DA (r_s=0.94; p0.001). The results indicate that the concentrations of transmitter substances measured in CSF at the lumbar level not necessarily are indicative for concentrations measured more centrally. The negative correlations between Evans ratio and L-CSF VIP (r_s=-0.76; p 0.001), and between resistance to outflow and V-CSF as well as L-CSF CCK (r_s=-0.75); p 0.05) might be explained by a reduction in number of cortical neurons or by disturbances in CSF dynamics in patients with NPH.