Thesis (D.PT.)--Sage Colleges, 2010. / "May 2010." "A Capstone project for PTY 768 presented to the faculty of The Department of Physical Therapy Sage Graduate School in partial fulfillment of the requirements for the degree of Doctor of Physical Therapy." Includes bibliographical references.

Lumbar spine fusion (LSF) is a common surgical procedure used in the treatment of lower back pain. Numerous studies have been conducted investigating the effects of LSF. Biomechanical studies have found that mechanical changes at adjacent joints create cumulative stress and pain, while clinical studies suggest that many patients develop symptomatic adjacent segmental disease (ASD) following LSF, which may necessitate additional surgery. Recently, ASD pain following LSF has been attributed to accelerated sacroiliac (SI) joint degeneration. Normal SI joints are mobile segments adjacent to the lumbosacral spine articulation and it has been hypothesized that altered biomechanics at the SI joints due to LSF could accelerate degeneration of the joints. The purpose of this study was to obtain a better understanding of the biomechanics at the SI joints and to determine whether LSF causes biomechanical changes at the SI joints. Six cadaver pelves were tested in flexion/extension, torsion, double leg compression and single leg compression, under four conditions: 1) intact, 2) after a 360 degree instrumented fusion at L4-5, 3) after a 360 degree instrumented lumbosacral fusion at L4-S1 and 4) after a unilateral SI joint fusion. Anterior and posterior SI joint movements were recorded during the study, along with load/displacement data. This study proved that motion does exist at the SI joints, although it is quite variable between specimens and between right and left SI joints within an individual specimen. It was also determined that changes in biomechanics do occur at the SI joints following fusion (L4-5, L4-S1 and unilateral SI joint fusion). Anteriorly, an overall increase in motion was detected at the SI joints during axial compression as fusions were performed. The posterior SI joints also demonstrated increased motion, however, this increase was detected in all of the parameters tested (flexion/extension, torsion and axial compression). However, due to the small number and variability of specimens tested, significance could not be established. The results of this study may help surgeons make more informed decisions, by being made aware of SI joint degeneration as a possible side effect of fusion surgeries, and taking that into consideration when determining a treatment plan.

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Diss. (sammanfattning) Stockholm : Karolinska institutet, 2007. / Härtill 5 uppsatser.

Degeneration of the cervical spine is part of the normal aging process, usually occurring without clinical symptoms. Symptomatic degeneration most often occurs in the lower cervical spine, presenting as axial neck pain, radiculopathy, myelopathy, or any combination of the three. When conservative treatment does not adequately manage these symptoms, surgical intervention may be required. The longstanding surgical treatment for cervical degeneration is arthrodesis achieved through anterior cervical discectomy and fusion (ACDF). A relatively newer treatment is arthroplasty with a cervical total disc replacement (CTDR), a motion-sparing procedure designed to maintain adjacent-level loading. While literature exists comparing the effects of cervical arthrodesis and cervical arthroplasty on neck kinematics and loading, the vast majority of these studies applied only quasi-static, non-injurious loading conditions. This dissertation research used a state-of-the-art, full body human finite element (FE) model to investigate the effects of these surgical procedures on neck response during simulated dynamic impacts. A method was developed to measure cross-sectional forces and moments at each level of the neck in the FE model. Neck loading was captured during three automobile impact simulations: a frontal impact of a belted driver with airbag deployment, a frontal impact of a belted passenger without airbag deployment, and an unbelted side impact. The measured neck forces and moments were compared to existing injury threshold values and used to calculate injury criteria values. Four additional simulations of the frontal impact with the belted driver were conducted with neck modifications representative of either a fusion or arthroplasty of C5-6. While cross-sectional loading above and below the implants did not vary appreciably, key differences were noted in both the interbody and facet response. However, no neck injury thresholds were exceeded in any of the simulations. With cervical radiculopathy diagnosed in 24,742 active-duty U.S. military personnel between 2000 and 2009, interest in cervical arthroplasty as treatment for symptomatic cervical degeneration in this population has increased. This motion-sparing procedure has the potential to expedite post-operative recovery time, allowing for these highly trained individuals to return to active-duty sooner than with a fusion. Due to the physically demanding nature of the military environment, it is important to ensure that this surgical procedure does not increase the likelihood of a neck injury. An FE simulation environment was developed to investigate aviator head and neck response during a survivable, rotary-wing aircraft impact with the ground using both an anthropomorphic test device (ATD) and a human body model. The head and neck response of the ATD FE simulation was successfully validated against the results of a previously conducted experimental sled test. A more biofidelic head and neck response was produced with the human body model, including realistic changes in neck curvature. Additional simulations were conducted with the human body model to investigate the neck response after cervical arthroplasty of C5-6. While the adjacent-level, cross-sectional loading for the C5-6 segment was not appreciably altered by the CTDRs, the interbody range-of-motion was increased; subsequently altering both the interbody and cervical facet loading. Again, no neck injury thresholds were exceeded in these simulations. Overall, cervical arthroplasty did not appear to have a deleterious effect on the dynamic neck response during a simulated rotary-wing aircraft impact. / Ph. D.

Master of Science / Department of Clinical Sciences / James D. Lillich / Objective - To compare the biomechanical characteristics of the currently recommended (CR) technique and a less invasive (LI) surgical approach for arthrodesis of the proximal interphalangeal joint (PIPJ). Additionally, to describe a technique for cartilage removal and disruption of the subchondral bone. Study design - Randomized paired limb design for biomechanical comparison. Cartilage removal and subchondral bone disruption was accomplished using an orthopedic drill bit. Sample Population – 76 cadaver limbs. Methods - Cadaver PIPJs were drilled using a 3.5mm, 4.5mm or 5.5mm drill bit. Articular surfaces were digitally photographed and analyzed. Other paired PIPJs were arthrodesed using either the CR or the LI surgical technique. Implants consisted of a 3-hole DCP and two 5.5mm transarticular screws. Constructs were tested to failure in dorso-palmar/plantar and latero-medial in single cycle 3-point bending. The maximum load and yield load was measured and composite stiffness was calculated and statistically compared. Results - The LI technique had significantly greater mean yield load (11.3 ± 2.8 kN vs. 7.68 ± 1.1 kN, P=0.008) and mean maximum load (13.5 ± 3.1 kN vs. 10.1 ± 1.94 kN, P= 0.02) under latero-medial bending. Under dorso-palmar/plantar bending there was no statistical difference between the surgical approaches (P=0.5). The 4.5mm drill bit removed 42% ± 7.3 of the cartilage and disrupted subchondral bone. The LI technique had a decreased surgical time (19 ± 3 min.) when compared with the CR (31 ± 3 min.) technique. Conclusion – The LI technique results in a stronger composite as measured in 3-point bending, loaded to failure. Clinical Relevance – The LI surgical technique may be considered for clinical cases requiring arthrodesis of the PIPJ as there is no reduction in composite strength.

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.

Πρόκειται για μια προοπτικη, συγκριτική, τυχαιοποιημένη, κλινική και ακτινολογική μελέτη της εξέλιξης της πώρωσης οπισθοπλάγιας σπονδυλοδεσίας με τη χρήση είτε αυτόλογου μοσχευματός είτε κοραλλιογενους υδροξυαπατίτη είτε μιγματος των δύο. Μελετήθηκαν 3 ομάδες ασθενών Α, Β και Γ με 18, 19 και 20 ασθενείς αντιστοιχά. Στην πρώτη ομάδα χρησιμοποιήθηκε μόνο αυτόλογο μόσχευμα, στη δεύτερη κοραλλιογενής υδροξυαπατίτης και αυτόλογο μόσχευμα και στην τρίτη ομάδα μόνο κοραλλιογενής υδροξυαπατίτης. Η εκτίμηση ήταν κλινική και ακτινολογική. Διαπιστώθηκε ότι η ενσωμάτωση του κοραλλιογενούς υδροξυαππατίτη χρειάζεται επααρκή αποφλοιωμένη οστική επιφάνεια και η τοποθετηση του στα οπισθοπλάγια σπονδυλικά στοιχεία δεν οδηγεί σε σπονδυλοδεσία. Όμως η τοποθετησή του κοραλλιογενούς υδροξυαπατίτη στα οπίσθια σπονδυλικά στοιχεία οδηγεί σε σπονδυλοδεσία στον αναμενόμενο χρόνο. / This prospective longitudinal randomized clinical and radiological study compared the evolution of instrumented posterolateral lumbar and lumbosacral fusion using either coralline hydroxyapatite or iliac bone graft or both. Three comparable groups A, B, and C were evaluated. In group A only autograft was used. In group B autograft and coralline hydroxyapatite were used and in group C only coralline hydroxyapatite was used as graft extender. The goups were evaluated clinically and radiologicalý It was found that coralline hydroxyapatite applied in the poserolateral spinal elements does not leed to a spinal fusion because of lack of bleeding osseous surfaces. However if coralline hydroxyapatite is applied in the laminae of the posterior spine it leeds to spinal fusion within the expected time.

Made available in DSpace on 2015-03-26T13:46:45Z (GMT). No. of bitstreams: 1 texto completo.pdf: 1599869 bytes, checksum: 2dfc6e687f4f13a1d1f2937967404955 (MD5) Previous issue date: 2005-02-18 / The aim of this study was to evaluate, in a experimental form, the surgical technique to get the arthrodesis on the tibiotarsal joint using 304L self-tapping stainless steel screws. Ten healthy adult female canines, with of a non-defined breed , whose weight ranged from 15 to 20 Kg were used. After exposition and condrectomy, the tibiotarsal joint was manually kept at an angle of around 135°, and a hole was drilled following the postero/anterior direction through the calcaneus tuber up to the dorsal cortex of the tibia area, where the screw was introduced. After that a second hole was drilled, this time following the latero-distal direction of the calcaneus crossing the talus up to the cortex of the medial malleolus, allowing the insertion of a second screw. The incised tissues were sewed the usual way. The animals went through a daily clinical evaluation within the first 15 days and then on 30th, 45 th, 60th, 90th and 120th days. X-ray exams were done over the operated member, immediately after the surgery and then on the 15th, 30th, 45 th, 60th, 90th and 120th days. Among the ten evaluated dogs, four went through another surgical intervention 120 days after the inicial intervention in order to have the implants removed and then they went on to be evaluated for another 30 days. The animals presented a satisfactory clinical healing with variable lameness degrees and normal deambulation around 50 and 60 days after the surgery. An X-ray exam showed the joint fusion about 45 days later. Osteolisis was seen around the screws that neither damaged the immobilization nor caused their migration. The results obtained with such a technique a conclusion that there was an adequate stability of the tibiotarsal joint, favoring a rigid bone fusion of the joint extremities, which was confirmed after the implant was removed. / O objetivo deste trabalho foi avaliar de forma experimental a técnica cirúrgica proposta na artrodese da articulação tibiotársica, com o uso de parafusos de aço inoxidável 304L auto-atarraxantes. Foram utilizadas 10 cadelas adultas, hígidas, sem raça definida, com peso compreendido entre 15 e 20 kg. Após a exposição e condrectomia articular, a articulação tibiotársica foi mantida manualmente num ângulo de aproximadamente 135°, e um orifício foi realizado no sentido plantarodorsal através do tubérculo do calcâneo até a região cortical dorsal da tíbia, onde foi introduzido um parafuso. Ato contínuo, um segundo orifício foi produzido na direção da superfície laterodistal do calcâneo passando através do talus até a cortical do maléolo medial, permitindo a inserção do segundo parafuso. Os tecidos incisados foram suturados de maneira rotineira. Os animais passaram por avaliação clínica diária nos primeiros 15 dias e aos 30, 45, 60, 90, e 120 dias. Foram conduzidos exames radiográficos, no membro operado, imediatamente após o procedimento cirúrgico, e aos 15, 30, 45, 60, 90, e 120 dias. Quatro cães foram submetidos a um novo procedimento cirúrgico, 120 dias após a intervenção inicial para remoção dos implantes, e avaliados por mais 30 dias. Os animais apresentaram evolução clínica satisfatória, com graus variados de claudicação, apresentando deambulação normal entre 50 e 60 dias de pós-operatório. Radiograficamente, a fusão articular ocorreu em média aos 45 dias. Ao redor dos parafusos, foram observadas áreas de osteólise, que não comprometeram a imobilização e nem provocaram a migração dos mesmos. Os resultados obtidos permitem concluir que houve adequada estabilidade da articulação tibiotársica favorecendo uma rígida fusão óssea das extremidades articulares, confirmada após a retirada dos implantes.

The in vitro comparison of monotonic and cyclic mechanical properties of equine proximal interphalangeal joint arthrodeses stabilized using an open or closed technique and application of 2 abaxial transarticular lag screws combined with either an axial 4.5mm narrow 3-hole LC-DCP with 5.5mm cortical screws a 4.5mm narrow 3-hole LCP with 5.0mm locking screws. Limbs were tested for cyclic fatigue at 20,0000cycles and then in single-cycle to failure under 3-point, dorsopalmar bending. There were no significant differences in stiffness and single-cycle to failure values between the LCP and LC-DCP constructs, with or without PIPJ collateral ligament transaction. There was no interaction between the open and closed techniques, nor between plate types on force or stiffness at failure.