Nikolaos K. Paschos

Accuracy of pedicle screw placement: a systematic review of prospective in vivo studies comparing free hand, fluoroscopy guidance and navigation techniques.

IntroductionWith the advances and improvement of computer-assisted surgery devices, computer-guided pedicle screws insertion has been applied to the lumbar, thoracic and cervical spine. The purpose of the present study was to perform a systematic review of all available prospective evidence regarding pedicle screw insertion techniques in the thoracic and lumbar human spine. Materials and methodsWe considered all prospective in vivo clinical studies in the English literature that assessed the results of different pedicle screw placement techniques (free-hand technique, fluoroscopy guided, computed tomography (CT)-based navigation, fluoro-based navigation). MEDLINE, OVID, and Springer databases were used for the literature search covering the period from January 1950 until May 2010.Results26 prospective clinical studies were eventually included in the analysis. These studies included in total 1,105 patients in which 6,617 screws were inserted. In the studies using free-hand technique, the percentage of the screws fully contained in the pedicle ranged from 69 to 94%, with the aid of fluoroscopy from 28 to 85%, using CT navigation from 89 to 100% and using fluoroscopy-based navigation from 81 to 92%. The screws positioned with free-hand technique tended to perforate the cortex medially, whereas the screws placed with CT navigation guidance seemed to perforate more often laterally.ConclusionsIn conclusion, navigation does indeed exhibit higher accuracy and increased safety in pedicle screw placement than free-hand technique and use of fluoroscopy.

Normative data on hand grip strength in a Greek adult population.

The objectives of this study were to establish data concerning normal hand grip strength (GS) and to explore possible associations with anthropometric parameters. GS was measured in 232 individuals in a standard arm position using the Jamar dynamometer. We examined differences between right/left and dominant/nondominant hands. Possible correlations of GS with anthropometric values were evaluated. Right hand and dominant hand GS were found to be higher and statistically significant compared to left hand and nondominant hand GS, respectively. Men had higher values of GS compared to women. A negative association was observed between age and dominant hand GS. A positive association was documented between height and dominant hand GS, while the respective comparison for weight and dominant hand GS documented a statistically significant positive association only in the male group. A positive association between BMI and dominant hand GS was seen in female individuals. Additional factors associated with GS should be the goal of future investigations.RésuméEtablir des données concernant la force de serrage de la main (GS) et, explorer les possibles associations avec des paramètres anthropométriques. La force de la main: GS a été mesurée chez 232 individus en position standard du bras, utilisant le dynamomètre de Jamar. Nous avons examiné les différences entre les côtés droit et gauche et dominant/non-dominant. Les possibles corrélations de GS avec des valeurs anthropométriques ont été évaluées. Respectivement main droite et GS du côté dominant ont été retrouvées de manière significativement plus élevée que main gauche et GS non-dominant. Les hommes avaient des valeurs de GS plus élevées que les femmes. Une association négative a été retrouvée entre l’âge et la GS de la main dominante. Une association positive a été documentée entre la taille et la GS du côté dominant, tandis que la comparaison entre le poids et la GS du côté dominant montre une association positive de manière statistiquement significative, uniquement dans le groupe des hommes. Une association positive a été retrouvée entre le BMI et la GS du côté dominant dans le groupe des femmes. Des facteurs additionnels associés avec la GS devraient être le but d’une future investigation.

Advances in tissue engineering through stem cell-based co-culture

Stem cells are the future in tissue engineering and regeneration. In a co‐culture, stem cells not only provide a target cell source with multipotent differentiation capacity, but can also act as assisting cells that promote tissue homeostasis, metabolism, growth and repair. Their incorporation into co‐culture systems seems to be important in the creation of complex tissues or organs. In this review, critical aspects of stem cell use in co‐culture systems are discussed. Direct and indirect co‐culture methodologies used in tissue engineering are described, along with various characteristics of cellular interactions in these systems. Direct cell–cell contact, cell–extracellular matrix interaction and signalling via soluble factors are presented. The advantages of stem cell co‐culture strategies and their applications in tissue engineering and regenerative medicine are portrayed through specific examples for several tissues, including orthopaedic soft tissues, bone, heart, vasculature, lung, kidney, liver and nerve. A concise review of the progress and the lessons learned are provided, with a focus on recent developments and their implications. It is hoped that knowledge developed from one tissue can be translated to other tissues. Finally, we address challenges in tissue engineering and regenerative medicine that can potentially be overcome via employing strategies for stem cell co‐culture use. Copyright

Developing functional musculoskeletal tissues through hypoxia and lysyl oxidase-induced collagen cross-linking

Significance The inadequate mechanical properties of engineered tissues have prevented related therapies from clinical translation. Collagen cross-links correlate with the mechanical integrity of tissues; however, addressing the weakness of neotissues through enhancing collagen cross-links has not received the attention it deserves. The present study demonstrates, both in vitro and in vivo, that improvements in the mechanical properties of native and engineered tissues can be attained using endogenous (hypoxia-mediated) lysyl oxidase and exogenous application of lysyl oxidase-like 2, which are enzymes responsible for collagen cross-linking. By promoting an ∼16-fold increase in collagen cross-linking and, concomitantly, an approximately fivefold enhancement in the neotissue’s mechanical properties, this work creates new prospects for regenerative medicine. The methods developed here work across a spectrum of collagen-rich tissues and are clinically applicable. The inability to recapitulate native tissue biomechanics, especially tensile properties, hinders progress in regenerative medicine. To address this problem, strategies have focused on enhancing collagen production. However, manipulating collagen cross-links, ubiquitous throughout all tissues and conferring mechanical integrity, has been underinvestigated. A series of studies examined the effects of lysyl oxidases (LOXs), enzymes responsible for the formation of collagen cross-links. Hypoxia-induced endogenous LOX was applied in multiple musculoskeletal tissues (i.e., cartilage, meniscus, tendons, ligaments). Results of these studies showed that both native and engineered tissues are enhanced by invoking a mechanism of hypoxia-induced pyridinoline (PYR) cross-links via intermediaries like LOX. Hypoxia was shown to enhance PYR cross-linking 1.4- to 6.4-fold and, concomitantly, to increase the tensile properties of collagen-rich tissues 1.3- to 2.2-fold. Direct administration of exogenous lysyl oxidase-like 2 (LOXL2) was applied in native cartilage and neocartilage generated using a scaffold-free, self-assembling process of primary chondrocytes. Exogenous LOXL2 was found to enhance native tissue tensile properties 1.9-fold. LOXL2 concentration- and time-dependent increases in PYR content (∼16-fold compared with controls) and tensile properties (approximately fivefold compared with controls) of neocartilage were also detected, resulting in properties on par with native tissue. Finally, in vivo subcutaneous implantation of LOXL2-treated neocartilage in nude mice promoted further maturation of the neotissue, enhancing tensile and PYR content approximately threefold and 14-fold, respectively, compared with in vitro controls. Collectively, these results provide the first report, to our knowledge, of endogenous (hypoxia-induced) LOX and exogenous LOXL2 applications for promoting collagen cross-linking and improving the tensile properties of a spectrum of native and engineered tissues both in vitro and in vivo.

Comparative study of surgical treatment of ulnar nerve compression at the elbow.

HYPOTHESIS The optimal surgical treatment for cubital tunnel syndrome remains unclear. We aim to evaluate the long-term outcome of surgical treatment by comparing the results of the different methods proposed. MATERIALS AND METHODS We retrospectively reviewed 113 patients in whom 3 different surgical methods were used for cubital tunnel syndrome treatment. In situ decompression, partial epicondylectomy, and anterior subcutaneous transposition were performed from 1997 to 2007. RESULTS Results were graded as excellent in 51 patients (45%), good in 34 (30%), fair in 8 (7%), and poor in 20 (18%). When we compared the results among the different surgical procedures, good and excellent results were achieved in 26 of 31 patients (84%) treated with in situ decompression, 36 of 45 (80%) treated with release and partial medial epicondylectomy, and 23 of 37 (62%) treated with release and anterior subcutaneous transposition of the nerve. CONCLUSIONS Our results indicate that in situ decompression and partial epicondylectomy both represent efficient and safe methods for cubital tunnel syndrome management. In patients in whom anterior subcutaneous transposition was performed, although they had a significant improvement of their clinical signs and symptoms, they had an inferior outcome when compared with patients treated with the other 2 methods.

Combined use of chondroitinase-ABC, TGF-β1, and collagen crosslinking agent lysyl oxidase to engineer functional neotissues for fibrocartilage repair.

Patients suffering from damaged or diseased fibrocartilages currently have no effective long-term treatment options. Despite their potential, engineered tissues suffer from inferior biomechanical integrity and an inability to integrate in vivo. The present study identifies a treatment regimen (including the biophysical agent chondroitinase-ABC, the biochemical agent TGF-β1, and the collagen crosslinking agent lysyl oxidase) to prime highly cellularized, scaffold-free neofibrocartilage implants, effecting continued improvement in vivo. We show these agents drive in vitro neofibrocartilage matrix maturation toward synergistically enhanced Youngs modulus and ultimate tensile strength values, which were increased 245% and 186%, respectively, over controls. Furthermore, an in vitro fibrocartilage defect model found this treatment regimen to significantly increase the integration tensile properties between treated neofibrocartilage and native tissue. Through translating this technology to an in vivo fibrocartilage defect model, our results indicate, for the first time, that a pre-treatment can prime neofibrocartilage for significantly enhanced integration potential in vivo, with interfacial tensile stiffness and strength increasing by 730% and 745%, respectively, compared to integration values achieved in vitro. Our results suggest that specifically targeting collagen assembly and organization is a powerful means to augment overall neotissue mechanics and integration potential toward improved clinical feasibility.

Endoscopic Versus Open Carpal Tunnel Release

PURPOSE This study compared endoscopic carpal tunnel release with the conventional open technique with respect to short- and long-term improvements in functional and clinical outcomes. METHODS We assessed 72 outpatients diagnosed with carpal tunnel syndrome. Of these patients, 37 underwent the endoscopic method according to Chow and 35 were assigned to the open method. Improvement in symptoms, severity, and functionality were evaluated at 2 days, 1 week, 2 weeks, and 1 year postoperatively. Changes in clinical outcomes were evaluated at 1 year postoperatively. Complications were also assessed. RESULTS Both groups showed similar improvement in all but 1 outcome 1 year after the release; increase in grip strength was significantly higher in the endoscopic group. However, the endoscopic method showed a greater improvement in symptoms and functional status compared with the open method at 2 days, 1 week, and 2 weeks postoperatively. Separate analysis of the questions referring to pain showed that the delay in improvement in the open group was because of the persistence of pain for a longer period. Paresthesias and numbness decrease immediately after the operation with comparable rates for both groups. CONCLUSIONS Endoscopic carpal tunnel release provides a faster recovery to operated patients for the first 2 weeks, with faster relief of pain and faster improvement in functional abilities. Paresthesia and numbness subside in an identical manner with the 2 techniques. At 1 year postoperatively, both open and endoscopic techniques seem to be equivalently efficient.

Recent updates of surgical techniques and applications of free vascularized fibular graft in extremity and trunk reconstruction.

Successful free vascularized bone transfers have revolutionized the limb salvage and musculoskeletal reconstruction. The free vascularized fibula remains the mainstay in bone reconstruction combines the benefits of blood supply, biological potential, and callus formation with its unique biomechanical characteristics offering a supreme candidate for various dissolvable issues. Especially in conditions where there was lack of other applicable method and the free vascularized fibular graft was introduced as the only alternative. Extensive traumatic bone loss, tumor resection, femoral head osteonecrosis and congenital defects have been managed with exceptional results beyond expectations. The present manuscript updates several issues in application of free vascularized fibular graft in extremity and trunk reconstruction. It also highlights tips and pearls of surgical technique in some crucial steps of harvesting the vascularized fibular graft in order to offer a vascularized bone with safety and low donor site morbidity.

Primary closure versus non-closure of dog bite wounds. A randomised controlled trial

INTRODUCTION Dog bite wounds represent a major health problem. Despite their importance, their management and especially the role of primary closure remain controversial. In this randomised controlled trial, the outcome between primary suturing and non-closure was compared. METHODS 168 consecutive patients with dog bite injuries were included in this study. The wounds were allocated randomly in two treatment approaches: Group 1, consisting of eighty-two patients, had their wound sutured, whilst Group 2, consisting of eighty-six patients, did not have their wounds sutured. All wounds were cleansed using high-pressure irrigation and povidone iodine. All patients received the same type of antibiotic treatment. Our measured outcomes included presence of infection and cosmetic appearance. Cosmetic outcome was evaluated using the Vancouver Scar Scale (VSS). Wound and patient characteristics, such as time of management, wound location and size, and patient age, were recorded and analysed for their potential role in the resulting outcome. RESULTS The overall infection rate was 8.3%. No difference in the infection rate between primary suturing and non-suturing group was detected in the present study. The cosmetic appearance of the sutured wounds was significantly better (mean score 1.74) compared to the wounds that were left open (mean score 3.05) (p=0.0001). The infection rate was comparable among all age groups. Wounds treated within 8h of injury demonstrated an infection rate of 4.5%, which is lower compared to the 22.2% rate observed in wounds treated later than 8h. The wounds located at the head and neck exhibited better results in both infection rate and cosmetic outcome. Additionally, wounds >3 cm negatively affected the cosmetic appearance of the outcome. CONCLUSIONS Primary suturing of wounds caused by dog bites resulted in similar infection rate compared to non-suturing. However, primary suturing exhibited improved cosmetic appearance. Time of management appeared to be critical, as early treatment resulted in lower infection rate and improved cosmetic appearance regardless suturing or not. Furthermore, wounds located at the head and face demonstrated better results.

Review article: Patellar instability after total knee arthroplasty

Patellar instability after total knee arthroplasty (TKA) is a serious complication that impairs functional outcome and may lead to revision surgery. Its aetiology can be related to the surgical technique and component positioning, extensor mechanism imbalance, and other causes. After TKA, the presence of anterior knee pain, especially during stressful activities, is indicative of patellar instability. Diagnosis can be made by radiological evaluation of the patella position, alignment, and component fixation. Main treatment options include revision of the TKA components (in case of malposition) and lateral retinacular release with or without a proximal or distal realignment (in case of soft-tissue imbalance).