A cost-effective surgical navigation solution for periacetabular osteotomy (PAO) surgery.

PURPOSE To evaluate a low-cost, inertial sensor-based surgical navigation solution for periacetabular osteotomy (PAO) surgery without the line-of-sight impediment. METHODS Two commercial inertial measurement units (IMU, Xsens Technologies, The Netherlands), are attached to a patient's pelvis and to the acetabular fragment, respectively. Registration of the patient with a pre-operatively acquired computer model is done by recording the orientation of the patient's anterior pelvic plane (APP) using one IMU. A custom-designed device is used to record the orientation of the APP in the reference coordinate system of the IMU. After registration, the two sensors are mounted to the patient's pelvis and acetabular fragment, respectively. Once the initial position is recorded, the orientation is measured and displayed on a computer screen. A patient-specific computer model generated from a pre-operatively acquired computed tomography scan is used to visualize the updated orientation of the acetabular fragment. RESULTS Experiments with plastic bones (eight hip joints) performed in an operating room comparing a previously developed optical navigation system with our inertial-based navigation system showed no statistically significant difference on the measurement of acetabular component reorientation. In all eight hip joints the mean absolute difference was below four degrees. CONCLUSION Using two commercially available inertial measurement units we show that it is possible to accurately measure the orientation (inclination and anteversion) of the acetabular fragment during PAO surgery and therefore to successfully eliminate the line-of-sight impediment that optical navigation systems have.

Effect of tympanic cavity evacuation and flushing on microbial isolates during total ear canal ablation with lateral bulla osteotomy in dogs.

OBJECTIVE To evaluate differences in bacterial numbers, identity, and susceptibility in samples obtained from the tympanic cavity on entry (preflush) and after evacuation and lavage (postflush) and assess perioperative and empiric antimicrobial selection in dogs that underwent total ear canal ablation (TECA) with lateral bulla osteotomy (LBO) or reoperation LBO. DESIGN Prospective clinical study. ANIMALS 34 dogs. PROCEDURE TECA with LBO or reoperation LBO was performed on 47 ears. Pre- and postflush aerobic and anaerobic samples were obtained from the tympanic cavity. Isolates and antimicrobial susceptibility patterns were compared. RESULTS Different isolates (31/44 [70%] ears) and susceptibility patterns of isolate pairs (6/44 [14%] ears) were detected in pre- and postflush samples from 84% of ears. Evacuation and lavage of the tympanic cavity decreased the number of bacterial isolates by 33%. In 26% of ears, bacteria were isolated from post-flush samples but not preflush samples. Only 26% of isolates tested were susceptible to cefazolin. At least 1 isolate from 53% of dogs that received empirically chosen antimicrobials postoperatively was resistant to the selected drugs. Anaerobic bacteria were recovered from 6 ears. CONCLUSIONS AND CLINICAL RELEVANCE Accurate microbiologic assessment of the tympanic cavity should be the basis for selection of antimicrobials in dogs undergoing TECA with LBO. Bacteria remain in the tympanic cavity after evacuation and lavage. Cefazolin was a poor choice for dogs that underwent TECA with LBO, as judged on the basis of culture and susceptibility testing results.

Surgical Technique: Reverse Periacetabular Osteotomy

Acetabular retroversion is the result of an externally rotated hemipelvis rather than a focal overgrowth of the anterior wall and/or hypoplasia of the posterior wall. Acetabular retroversion is a cause of pincer impingement which, if left untreated, can lead to hip pain and osteoarthritis. The causal surgical treatment in hips with acetabular retroversion is acetabular reorientation with a reverse periacetabular osteotomy (PAO). Indication is based on a positive correlation among symptoms (typically groin pain), physical findings on examination (positive anterior impingement test and decreased flexion and internal rotation), and radiographic signs for acetabular retroversion. These include a positive crossover, posterior wall, and ischial spine sign. A reverse PAO is performed with four osteotomies and a controlled fracture. Unlike reorientation of the acetabular fragment in dysplastic hips, correction for acetabular retroversion is achieved by a combined extension and internal rotation of the acetabular fragment. Typically, a small supra-acetabular wedge resection is required to allow sufficient extension of the fragment. The quality of acetabular reorientation is evaluated by intraoperative AP pelvic radiographs. In addition, intraoperative testing of range of motion following acetabular reorientation is mandatory. An arthrotomy and offset correction of the femoral head-neck area is indicated in hips with decreased internal rotation following acetabular reorientation. In a 10-year follow-up study of reverse PAO, a favorable outcome with preservation of all native joints was found. Correct acetabular orientation and, if necessary, a concomitant offset correction were the keys of successful outcome.

Tibial Nerve Stimulation for Treating Neurogenic Lower Urinary Tract Dysfunction: A Systematic Review

CONTEXT Tibial nerve stimulation (TNS) is a promising therapy for non-neurogenic lower urinary tract dysfunction and might also be a valuable option for patients with an underlying neurological disorder. OBJECTIVE We systematically reviewed all available evidence on the efficacy and safety of TNS for treating neurogenic lower urinary tract dysfunction (NLUTD). EVIDENCE ACQUISITION The review was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Statement. EVIDENCE SYNTHESIS After screening 1943 articles, 16 studies (4 randomized controlled trials [RCTs], 9 prospective cohort studies, 2 retrospective case series, and 1 case report) enrolling 469 patients (283 women and 186 men) were included. Five studies reported on acute TNS and 11 on chronic TNS. In acute and chronic TNS, the mean increase of maximum cystometric capacity ranged from 56 to 132mL and from 49 to 150mL, and the mean increase of bladder volume at first detrusor overactivity ranged from 44 to 92mL and from 93 to 121mL, respectively. In acute and chronic TNS, the mean decrease of maximum detrusor pressure during the storage phase ranged from 5 to 15cm H2O and from 4 to 21cm H2O, respectively. In chronic TNS, the mean decrease in number of voids per 24h, in number of leakages per 24h, and in postvoid residual ranged from 3 to 7, from 1 to 4, and from 15 to 55mL, respectively. No TNS-related adverse events have been reported. Risk of bias and confounding was high in most studies. CONCLUSIONS Although preliminary data of RCTs and non-RCTs suggest TNS might be effective and safe for treating NLUTD, the evidence base is poor, derived from small, mostly noncomparative studies with a high risk of bias and confounding. More reliable data from well-designed RCTs are needed to reach definitive conclusions. PATIENT SUMMARY Early data suggest tibial nerve stimulation might be effective and safe for treating neurogenic lower urinary tract dysfunction, but more reliable evidence is required.

Craniofacial Adaptations After Total Maxillary Osteotomy in Macaca Irus: A Cephalometric and Histologic Study

Submitted in partial fulfillment of the requirements for a Certificate in Orthodontics, Dept. of Orthodontics, University of Connecticut Health Center, 1977

Ultrasound Guided lateral Infra-trochanteric Sciatic Nerve Blockade for Proximal Tibial Surgery: A Novel Technique

Sciatic nerve blockade (SNB) can be performed at several point along its anatomic course. Proximal SNB techniques described include the classic Labat, sacral (Mansur), infragluteal (Raj), and anterior approches Distal SNB techniques include the mid-femoral, posterior and lateral popliteal and mid-tibial approaches. The anatomic region of the lower extramity to be anesthetixzed will determine the appropriate SNB technique to use for the operative procedure.

Effect of cyclic pneumatic soft tissue compression on simulated distal radius fractures

We investigated the effect of pneumatic pressure applied to the proximal musculature of the sheep foreleg on load at the site of a transverse osteotomy of the distal radius. The distal radii of 10 fresh sheep foreleg specimens were osteotomized and a pressure sensor was inserted between the two bone fragments. An inflatable cuff, connected to a second pressure sensor, was positioned around the proximal forelimb musculature and the leg then was immobilized in a plaster cast. The inflatable cuff was inflated and deflated repeatedly to various pressures. Measurements of the cuff pressure and corresponding change in pressure at the osteotomy site were recorded. The results indicated that application of pneumatic pressure to the proximal foreleg musculature produced a corresponding increase in load at the osteotomy site. For the cuff pressures tested (109.8-238.4 mm Hg), there was a linear correlation with the load at the osteotomy site with a gradient of 12 mm Hg/N. It is conceivable, based on the results of this study, that a technique could be developed to provide dynamic loading to accelerate fracture healing in the upper limb of humans.

Strain and excursion of the sciatic, tibial, and plantar nerves during a modified straight leg raising test

A modified straight leg raising (SLR) in which ankle dorsiflexion is performed before hip flexion has been suggested to diagnose distal neuropathies such as tarsal tunnel syndrome. This study evaluates the clinical hypothesis that strain in the nerves around the ankle and foot caused by ankle dorsiflexion can be further increased with hip flexion. Linear displacement transducers were inserted into the sciatic, tibial, and plantar nerves and plantar fascia of eight embalmed cadavers to measure strain during the modified SLR. Nerve excursion was measured with a digital calliper. Ankle dorsiflexion resulted in a significant strain and distal. excursion of the tibial nerve. With the ankle in dorsiflexion, the proximal excursion and tension increase in the sciatic nerve associated with hip flexion were transmitted distally along the nerve from the hip to beyond the ankle. As hip flexion had an impact on the nerves around the ankle and foot but not on the plantar fascia, the modified SLR may be a useful test to differentially diagnose plantar heel pain. Although the modified SLR caused the greatest increase in nerve strain nearest the moving joint, mechanical forces acting on peripheral nerves are transmitted well beyond the moving joint. (c) 2006 Orthopaedic Research Society.

Anisotropic properties of human tibial cortical bone as measured by nanoindentation

The purpose of this study was to investigate the effects of elastic anisotropy on nanoindentation measurements in human tibial cortical bone. Nanoindentation was conducted in 12 different directions in three principal planes for both osteonic and interstitial lamellae. The experimental indentation modulus was found to vary with indentation direction and showed obvious anisotropy (oneway analysis of variance test, P < 0.0001). Because experimental indentation modulus in a specific direction is determined by all of the elastic constants of cortical bone, a complex theoretical model is required to analyze the experimental results. A recently developed analysis of indentation for the properties of anisotropic materials was used to quantitatively predict indentation modulus by using the stiffness matrix of human tibial cortical bone, which was obtained from previous ultrasound studies. After allowing for the effects of specimen preparation (dehydrated specimens in nanoindentation tests vs. moist specimens in ultrasound tests) and the structural properties of bone (different microcomponents with different mechanical properties), there were no statistically significant differences between the corrected experimental indentation modulus (Mexp) values and corresponding predicted indentation modulus (Mpre) values (two-tailed unpaired t-test, P < 0.5). The variation of Mpre values was found to exhibit the same trends as the corrected Mexp data. These results show that the effects of anisotropy on nanoindentation measurements can be quantitatively evaluated. © 2002 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved.

Effect of anisotropy on elastic moduli measured by nanoindentation in human tibial cortical bone

Many biological materials are known to be anisotropic. In particular, microstructural components of biological materials may grow in a preferred direction, giving rise to anisotropy in the microstructure. Nanoindentation has been shown to be an effective technique for determining the mechanical properties of microstructures as small as a few microns. However, the effects of anisotropy on the properties measured by nanoindentation have not been fully addressed. This study presents a method to account for the effects of anisotropy on elastic properties measured by nanoindentation. This method is used to correlate elastic properties determined from earlier nanoindentation experiments and from earlier ultrasonic velocity measurements in human tibial cortical bone. Also presented is a procedure to determine anisotropic elastic moduli from indentation measurements in multiple directions. © 2001 John Wiley & Sons, Inc. J Biomed Mater Res.

Recurrent Tibial Tunnel Cyst Formation Following Anterior Cruciate Ligament Reconstruction and Interference Screw Removal

A unique case of a collegiate athlete who suffered an anterior cruciate ligament injury leading to the formation of a synovial cyst is described. The cyst, localized over the tibial tunnel, resulted from irritation caused by the removal of interference screws.

L'effet d'une variation du niveau d'activité physique sur les propriétés électrophysiologiques des motoneurones du nerf tibial chez le rat

Thèse numérisée par la Direction des bibliothèques de l'Université de Montréal.