Repair and remodeling of bone during healing and fusion require a combination of bone resorption and formation to successfully restore the bone to its previous strength. The healing process is highly responsive to the mechanical conditions of the construct, where excessive loading can cause high strains that delay healing, but moderate loading can be beneficial. Maintaining compression at the site of fracture can benefit healing by maintaining bone congruency and increasing the stability of the bone-implant construct to prevent excessive shifting. For these reasons, compressive mechanisms are employed in many orthopaedic devices, including both intramedullary (IM) nails and external fixators for ankle arthrodesis applications. Tibiotalocalcaneal (TTC) arthrodesis is a salvage procedure that fuses both the ankle and the subtalar joints. It has become the standard of care in ankle degeneration, which can be brought on by posttraumatic arthritis, failed total ankle arthroplasty, or diabetic conditions such as Charcot arthropathy. While current devices are effective in many cases, TTC arthrodesis procedures still incur failure rates as high as 22%, where failure of the bones to successfully fuse can result in amputation. Because bone healing relies upon bone resorption, the initial compression applied to the implanted constructs can be quickly lost, which may sacrifice the stability of the structure and delay or inhibit further healing. By employing a mechanism that can sustain compression during the bone healing process, it was possible to increase the stability of the construct even during bone resorption, minimizing the failures that still occur. The focus of this study was to determine the effects of compression on the mechanical stability of the implant-bone construct found in TTC arthrodesis. A comparison was made between the torsional stability of two currently marketed intramedullary devices, as well as a prototype IM device comprised of a nickel titanium core, designed to hold constant compression for up to 9mm of resorption. Additionally, the stability of each construct over time was evaluated by correlating bone resorption to a loss in compressive force.

Osseointegration, or the direct integration of an implant into bone tissue, is necessary for implant success. Titanium is commonly used clinically in dental and orthopaedic implants because of its passivating oxide layer, which facilitates osseointegration, and its mechanical properties such as a modulus of elasticity similar to bone. Diverse studies have shown that surface microtopography, chemistry, and surface energy affect osteoblast behavior. The problem with these studies is that they access the average behavior of a culture in response to a substrate and not the behavior of individual cells. The objective of this study was to develop a method for correlating the behavior of individual cells with the characteristics of the surface underneath them. More specifically, this work developed a method to correlate integrin beta-1 (β1) expression with the surface characteristics under individual cells. Integrins are cell surface receptors that bind to specific proteins in the extracellular matrix adsorbed on the implant surface. Previous work has shown that expression of certain integrins is increased when osteoblasts on titanium substrates develop a more differentiated phenotype, and that integrin β1 is necessary for osteoblast response to roughness on titanium substrates. This study used molecular beacons specific to integrin β1 to quantify integrin β1 expression of MG63 cells cultured on titanium disks. A template was designed to coordinate the location of cells using fluorescence microscopy and scanning electron microscopy (SEM) in reference to laser etchings on the disks. After live cell imaging, cells were fixed, dried, and critical point dried for focused ion beam (FIB) milling. Transmission electron microscopy (TEM) sections of cells identified with high and low integrin β1 molecular beacon intensity were milled, and cells with high and low integrin β1 molecular beacon intensity were also serial sectioned. While our TEM results were inconclusive, SEM images from serial sectioning showed contact points between the cell body and the substrate, consistent with previous results. Cells cultured on pretreatment (PT) or sandblasted acid etched (SLA) titanium surfaces were also serial sectioned, showing that cells on SLA surfaces have more regions of contact between the cells and the substrate than cells on PT surfaces. This work is significant as it is the first study to develop a method to correlate individual cell behavior with the substrate surface characteristics under the individual cells. Previous studies have reported the average cell behavior in response to their substrates, while this work allows for the study of substrate surface characteristics that positively affect integrin β1 expression in individual cells. Further optimization of the fluorescence imaging process and FIB milling process could be done, and the method developed in this study could be used in future studies to investigate surface characteristics after using other fluorescent analyses of cell behavior, such as immunocytochemistry.

This study compares the biomechanics of early cyclic valgus loading of the ulnar collateral ligament (UCL) of the elbow repaired by either the Jobe technique or the docking technique. Better understanding of the biomechanical properties of each reconstruction may help surgeons choose the optimal surgical technique, particularly in planning earlier rehabilitation programs. Sixteen fresh frozen cadaver limbs (eight pairs) were randomized to either the Jobe cohort or the docking cohort. First intact UCLs were tested, followed by the repaired constructions. A Bionix MTS apparatus applied a constant valgus load to the elbows at 70o flexion, and valgus displacement was measured and then used to calculate valgus angle displacement. The docking group had significantly less valgus angle displacement than the Jobe group at cycles 100 and 1,000 (p = 0.0189 and 0.0076, respectively). Four of the eight specimens in the Jobe group failed at the tendon-suture interface before reaching 1,000 cycles, at cycles 7, 24, 250, and 362. None of the docking specimens failed before reaching 1,000 cycles. In this cadaveric study, the docking technique resulted in less angulation of the elbow in response to cyclic valgus loading as compared to the Jobe technique. The better response to valgus loading of the docking reconstruction may translate into a better response to early rehabilitation. Further study is needed to determine if this difference translates into improved clinical outcomes.

Thesis (M.S. in M.S.E.)--School of Materials Science and Engineering, Georgia Institute of Technology, 2004. Directed by Rober Narayan. / Includes bibliographical references (leaves 85-92).

Thesis (M. Phil.)--University of Hong Kong, 2010. / Includes bibliographical references (leaves 97-108). Also available in print.

Polyetheretherketone (PEEK), a polymer with mechanical strength comparable to human bone, is gaining popularity in the orthopedic field because it can potentially relieve the clinical complications, such as stress shielding effect and inevitable implantation failure, which are caused by the mismatch of the mechanical strength between the current metallic implants and the implantation sites. However, it is bio-inert and requires supplementary modification. Plasma immersion ion implantation (PIII) has been well documented that it is a good way to improve the bioactivity of a biomaterial. It is a method that introduces new elements to the biomaterial, generating bio-functional groups on the material surface without altering its mechanical properties. Hence, the aim of this study is to improve the bioactivity of PEEK by modifying its surface chemistry with the use of water (H2O) and ammonia (NH3) plasma immersion ion implantation (PIII) without altering its mechanical properties. After PIII treatment, a series of surface characterization tests that provide information about the surface properties, such as surface energy, roughness, surface chemical composition and crystallinity of PIII-treated PEEK were carried out. Results show that both H2O PIII and NH3 PIII-treated PEEK had significantly higher surface energy and roughness than untreated PEEK. There was also no significant change in the crystallinity of the PIII-treated PEEK, indicating that PIII treatment will not alter the mechanical properties of PEEK. Improvement in wetting properties of PEEK samples suggest the formation of polar functional groups on the PIII-treated PEEK materials, while the increased in surface roughness may be due to the energetic bombardments of plasma ions on the material surface. The in vitro bioactivity of plasma-treated PEEK was investigated and confirmed with hMSC-TERT. Initial cell attachment, cell spreading area, cell proliferation and differentiation were studied. Cell adhesion and cell spreading were enhanced on PIII-treated PEEK, and higher cell viability was observed on PIII-treated PEEK. Moreover, cell proliferation was promoted on early time point and cell differentiation was also enhanced particularly on day 7 by measuring the alkaline phosphatase activity. Therefore, H2O-PIII and NH3-PIII treatments were able to promote the bioactivity of PEEK samples. / published_or_final_version / Orthopaedics and Traumatology / Master / Master of Philosophy

M. Tech. Electrical engineering. / Discusses the process of standing from a chair is the first movement to be affected by physical impairment or ageing. That justified the increase of researches around sit-to-stand movements nowadays.This thesis presents the design of a four links wearable device that can assist disable people to stand from a sitting position. The four links are joined at the ankle, the knee and the HAT (Head, Arm and Trunk) where actuators are mounted. The system is built around three controllers. The Goal Controller drives the links along their reference trajectories, the Stability Controller makes sure that the system does not collapse as it is rising, and the last controller combines the signal from the 2 first ones.The reference trajectories are obtained from data recorded from healthy people performing the movement. The main idea behind the present design is that from seat off, the floor projection of the body centre of pressure is evaluated and compared to the most stable position. The stability controller generates the torque necessary to compensate the deviation, while the third controller adjusts the level of participation of that torque to satisfy both the trajectory and the stability objectives. Similar idea was previously found in Prinz (2010).

Syfte: Syftet med denna studie var att jämföra graden av smärta och illamående hos två patientgrupper inom ortopedi som smärtlindrades med tablett Dolcontin/Depolan/Morfin eller tablett Oxycontin/Oxynorm postoperativt dag 0, 1 och 2. Syftet var även att undersöka vilka riskfaktorer enligt Apfel Risk Score som kan påverka grad av illamående samt att undersöka om en korrelation fanns mellan preoperativ information och incidensen av postoperativt illamående och kräkning (PONV). Metod: En komparativ studie med kvantitativ ansats. Data samlades in genom två olika enkäter, varav en enkät fylldes i av patienterna och en enkät av sjuksköterskorna. 48 patienter inkluderades i studien, 24 per substans. Både kvinnor och män som genomgått elektiva knä- eller höftarteroplastikoperationer deltog i studien och de var mellan 31-77 år. Mätinstrumentet som sjuksköterskorna använde sig av för att skatta smärta och illamående var visuell analog skala (VAS). Data analyserades i Statistic Package for the Social Science (SPSS) 10.1 med x2-test, oberoende t-test samt Mann-Whitney U-test. Resultat: Resultatet i studien visade att inte fanns någon signifikant skillnad gällande smärta och de två substanserna. Det fanns en signifikant skillnad gällande illamående och de två substanserna. Inget signifikant samband påvisades mellan illamående och riskfaktorerna i Apfel Risk Score. Det fanns heller inget signifikant samband mellan incidensen av PONV och patientens upplevelse av att ha fått noggrann information preoperativt. Slutsats: Då dokumentationen av smärta och illamående enligt VAS på sjuksköterskeenkäterna var bristfällig, kan inga säkra slutsatser dras. Mer forsknings krävs således inom detta område. / Aim: The aim of this study was to compare the rating of pain and nausea in two groups of patients in orthopedics that was pain relieved with tablet Dolcontin/Depolan/Morphine or tablet Oxycontin/Oxynorm postoperative day 0, 1 and 2. The aim was also to investigate the risk factors according to Apfel Risk Score that may affect the degree of nausea and to investigate whether a correlation existed between preoperative information and the incidence of postoperative nausea and vomiting (PONV). Method: A comparative study with quantitative approach. Data were collected through two different questionnaires, one that was filled out by the patients and the other questionnaire by the nurses. The study included 48 patients, 24 per substance. Both men and women, between 31-77 years old, who would undergo elective knee or hip replacement surgery, participated in the study. The measuring instrument that the nurses used to estimate the pain and nausea were visual analogue scale (VAS). Data were analyzed in the Statistic Package for the Social Science (SPSS) 10.1 with the x2-test, independent t-test and Mann-Whitney U-test. Results: The results of the study showed that there was no significant difference regarding pain and the two compounds. There was a significant difference regarding nausea and the two compounds. No significant correlation was found between nausea and the risk factors in the Apfel Risk Score. There was no significant correlation between the incidence of PONV and patient experience of receiving accurate information preoperatively. Conclusion: As the documentation of pain and nausea according to VAS on the nursing surveys were poor, no firm conclusions can be drawn. Further studies are necessary to confirm the results of this study.

Rotatorenmanschettenrupturen (RM-Rupturen) haben eine hohe Prävalenz in der Bevölkerung und kommen mit zunehmendem Alter gehäuft vor (Ozaki et al. 1988, Milgrom et al.1995). Die operative Rekonstruktion der RM gilt als Goldstandard der Behandlung. Unbehandelt neigen RM-Rupturen zu Progression und zu fettiger Infiltration des Muskelbauchs und zu Abnahme der Sehnenqualität (Goutallier et al. 1994). Im weiteren Verlauf droht eine Defektarthropathie mit schmerzhafter Bewegungsseinschränkung und hochgradigem Funktionsverlust der Extremität. Eine zeitgerechte Rekonstruktion der RM kann diesen Verlauf günstig beeinflussen und die Funktion des Schultergelenkes signifikant verbessern (Deutsch et al. 1997, Gladstone et al. 2007). Mit zunehmendem Funktionsanspruch, auch noch im fortgeschrittenen Alter, gewinnt die Rekonstruktion der RM zunehmend an Bedeutung (Worland et al. 1999). Die Rerupturrate der operativen Rekonstruktion ist hoch und wird je nach Autor mit bis zu 94% angegeben (Boileau et al. 2005, Galatz et al. 2004). Uneinigkeit herrscht in der Literatur über die Art der Primärrefixation der Sehne im Knochen (Bishop et al. 2006, Boileau et al. 2005, Galatz et al. 2004). Mehrere Autoren berichten, dass die Nahtankerreparatur der transossären Refixation gleichwertig bzw. überlegen ist (Reed et al., 1996, Klinger et al. 2007). Des Weiteren wird die Anzahl und das Platzierungsmuster der Nahtanker, im Hinblick auf die Primärstabilität, kontrovers diskutiert (Apreleva et al. 2002, Craft et al. 1996, Rossouw et al. 1997). 52 Ziel des Schulterchirurgen sollte es sein, eine möglichst hohe Primärfestigkeit der Rekonstruktion zu erreichen, des Weiteren sollte die Refixationsmethode die spannungsfreie Einheilung der Sehne ermöglichen, den Patienten möglichst schnell einer aktiven Rehabilitation zuführen und die Rerupturrate möglichst gering halten (Kim et al. 2005). Ziel der Arbeit war es zu zeigen, ob eine weitere Reihe Nahtanker eine höhere Primärstabilität in Abhängigkeit des verwendeten Nahtmaterials bietet. Hierzu wurden 32 frische Schafsschultern in 4 Gruppen zu je 8 Präparaten aufgeteilt. Eine vollständige RM-Ruptur wurde simuliert und anschließend wurden die Rupturen entweder mit einer Einreihen-Nahtankerversorgung (single-row-Technik) oder mit einer Zweireihen-Nahtankerversorgung (double-row-Technik) refixiert. Dabei kamen 2 verschiedene Nahtmaterialien zum Einsatz (nicht resorbierbares Polyesterfadenmaterial (Ethibond®) und nicht resorbierbares Polyethylenfadenmaterial (HiFi®) der Stärke 2.0). Die Präparate wurden in einer Zugmaschine auf ihre Zugfestigkeit getestet. Die double-row-Technik in Kombination mit nicht-resorbierbarem Polyethylenfadenmaterial (HiFi®, Gruppe IV) erzielte hierbei eine signifikant höhere Ausreißfestigkeit als die anderen Versorgungen. Mehrere Fixationspunkte der Verbindung Knochen-Faden/Naht-Sehne bei der double- row-Technik erreichen so durch eine gleichmäßige Lastverteilung eine höhere Zugfestigkeit Inwieweit diese erhöhte Primärfestigkeit eine Verbesserung des klinischen Ergebnisses und eine Reduktion der Rerupturrate erbringen kann, muss durch zukünftige klinisch-prospektive Studien validiert werden. Der Einsatz dieser kostenintensiven und operativ anspruchsvollen Methode ist unseres Erachtens nur dann gerechtfertigt, wenn die Anzahl an Revisionseingriffen hierdurch signifikant gesenkt werden kann.

The following work presents the design of a haptic training simulator for pedicle screw insertions in pediatric scoliosis surgery. In particular, the haptic simulator simulates the haptic sensations associated with probe channeling through the pedicle using the free-hand technique. The design includes 1 DOF custom haptic device, haptic model, and controller. The design is tested and evaluated for feasibility through a small pilot studying involving 5 expert surgeons. Significant agreement across expert surgeons was obtained regarding the feasibility and potential for the simulator to be a useful training tool.