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• Laminectomy is the conventional method for treating lumbar stenosis.
• Instability of the lumbar spine has been reported to occur as frequently 8-31% after laminectomy. Symptomatic instability may require additional surgery, including possibly fusion.
• Less extensive surgeries, like bilateral laminotomy can be done to treat stenosis. These less extensive surgeries may preserve the tissues that provide lumbar stability.
• We have tested motion patterns in human cadaveric lumbar spines after laminotomy and laminectomy.
• Our preliminary data suggest that bilateral laminotomy may lead to less instability.

• Cervical fractures and dislocations are common neck injuries.
• We have found that the majority of these injuries can be successfully managed without surgery.
• Halo vest immobilization is the most secure way to stabilize the cervical spine without surgery. In this method a graphite horseshoe-shaped ‘halo’ is placed around the head and connected to it by pins that engage the skull. This halo is then secured to a vest that fits on the patient’s chest.
• 74% of halos placed can remain in place for the planned duration and 85% successfully manage the cervical injury without the need for surgery.
• The major complications associated with halo management are pin tract infections and pin tract loosening.

• We examined the cumulative incidence of second lumbar spine operation (“reoperation”) following an initial lumbar operation for degenerative conditions using a hospital discharge registry.
• The 11-year cumulative incidence of reoperation following lumbar spine surgery was 19%.
• Patients with spondylolisthesis had a lower cumulative incidence of reoperation after fusion surgery than after decompression alone (17.1% vs. 28.0%; P= 0.002).
• For diagnoses other than spondylolisthesis, the cumulative incidence of reoperation was higher following fusion than following decompression alone (21.5% vs. 18.8%; p = 0.008).
• Among patients who underwent surgery for lumbar degenerative disease, more than twice as many had a fusion procedure in the 1997 to 2000 cohort (19.1%) compared with the 1990 to 1993 cohort (9.4%).
• The 4-year cumulative incidence of reoperation was higher in the 1997 to 2000 cohort compared with the 1990 to 1993 cohort (14.0% vs. 12.4%, p < 0.001).
• Among fusion patients, those in the 1997 to 2000 cohort were approximately 40% more likely to undergo a reoperation within the first year when compared with fusion patients the 1990 to 1993 cohort.
• A higher proportion of fusion procedures and the introduction of new spinal implants between 1993 and 1997 were not associated with reduced reoperation rates.

• The injured pelvis can regain the stability of its bony and ligamentous structures if they are held firmly in proper alignment during the healing process.
• Extensive, open surgical approaches have been associated with complications that interfere with healing.
• With minimally invasive yet stable methods for fracture fixation, the necessary restoration of anatomy can be achieved without the risks of open surgery.
• Accurate reduction and stable fixation of acetabular fractures avoids traction, allows early patient mobilization, and lowers the risk of post-traumatic hip arthritis.

• Bone loss during spaceflight has been a known health issue for more than 40 years.
• The mechanism appears to be enhanced resorption unbalanced by enhanced bone formation.
• Risk of fracture and renal stones have both been identified by NASA as potentially mission-limiting.
• Astronauts on long-duration missions typically lose 2% of hip bone mass per month.
• This loss is as much in a month as post-menopausal women lose in a year.
• International Space Station (ISS) crew members are returning with losses of up to 10% of proximal femoral in bone mineral density and 15% in predicted bone strength.
• The only countermeasure to bone loss that has been attempted to date is exercise.
• Our experiments on board the ISS have shown that exercise loads are less than those on Earth.
• 6-degree head-down bedrest is a ground-based analog of spaceflight.
• Our bedrest studies have shown that individualized exercise prescriptions can mitigate total hip bone loss in some people.
• A new resistance exercise device was recently delivered to the ISS.
• An experiment with oral bisphosphonates has been approved for flight.
• More information on bone loss in women astronauts is needed.
• Recovery from bone loss is lengthy and results in altered bone structure.

• Osteoporosis and resulting non-traumatic fractures are an inevitable consequence of aging and menopause.
• Anabolic options are required to build-up bone mass at adolescence such that nontraumatic fractures can be prevented later in life.
• Physical exercise offers promise as a therapy but requirements for high-impact, strenuous activity have prevented realization of this potential.
• We have therefore sought to design mild exercise based interventions by focusing upon observations that brief exercise (~ 2 – 3 mins) can elicit robust bone adaptation.
• Using this basis, we have developed a novel computational model that simulated activation of the Ca2+/NFAT pathway, a signaling mechanism critical in how bone cells and tissue perceive and respond to brief mechanical loading or physical exercise.
• Interestingly, optimization using this model suggested that loading bone once every 10 mins could result in substantially more bone formation than loading bone 1800 times over a 30 min ‘exercise’ bout.
• Remarkably, our preliminary experiments confirm predictions of this computational model, demonstrate the utility of our approach and suggest that mild activity can indeed be ‘engineered’ to be potently anabolic for the skeleton.
• Ultimately, a similar strategy could be used to design mild physical exercise to robustly build-up bone mass at adolescence as a bulwark against the inevitable ravages of age and menopause.

• In osteoporosis, the rate of bone regeneration fails to keep up with the rate of bone degeneration.
• Fragility factures in individuals with osteoporosis are debilitating, expensive and lethal.
• Having a fracture associated with osteoporosis significantly increases the risk of subsequent hip fracture.
• Fragility factures in individuals with osteoporosis are debilitating, expensive and lethal.
• 25% of patients who have a hip fracture will die within the first year following the hip fracture.
• 70% of proximal humerus fractures occur in women.
• Having a proximal humerus fracture increases the risk of having a hip fracture 6-fold within the first year following the humerus fracture.
• Interventions and medical treatments can substantially decrease the risk of subsequent hip fractures as soon as 3-6 months after initiation of treatment.

• Shoulder instability and shoulder dislocations are among the most commonly occurring and disabling of sports injuries.
• In the majority of cases, traumatic dislocations result not only in a disruption of the stabilizing glenohumeral ligaments, but also an impression/compression defect on the humeral head (termed a Hill-Sachs defect).
• When large enough, these volumetric bony defects will cause re-dislocation of the shoulder even after anatomic repair of the ligaments; these are termed engaging Hill-Sachs defects.
• Because the region of the defect is hard to access with traditional surgical approaches, previous treatment strategies have centered on open non-anatomical surgical procedures (Latarjet, Eben-Hybinette, etc) that alter the normal shoulder anatomy to try and prevent re-dislocation - these non-anatomic procedures can be complicated by shoulder stiffness and pain.
• Working in the University of Washington Arthroscopy, Research and Training Laboratory (ART-lab), the authors were able to develop a minimally invasive, arthroscopic technique that restores the circumferential surface area of the humeral head by grafting the volumetric bone loss with synthetic bio-conductive plugs.
• We present the short-term clinical results of this novel technique, which appears to restore exceptional range of motion and a return to athletic participation with a minimally invasive, anatomic procedure.

• Chondrolysis of the shoulder, (rapid dissolution of the articular cartilage), is being diagnosed with increased frequency since the advent of shoulder arthroscopy.
• No definitive etiology has been identified, although strong associations have been made with the use of thermal devices and with the administration of intra-articular anesthetics.
• When femur fractures were treated by bed rest and traction, they were complicated by pneumonia, bedsores, and bowel and bladder problems.
• Management of glenohumeral chondrolysis is problematic as many of the patients are very young for treatment with conventional total shoulder arthroplasty.
• We have analyzed the existing literature along with a series of new cases in search of factors that may contribute to the development of chondrolysis.
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• Shoulder arthritis is a disabling condition in which the normally smooth cartilage surfaces of the ball and socket of the shoulder are lost because of injury, degeneration, inflammation, or surgical misadventure.
• Modern shoulder replacement surgery was introduced by Dr. Charles S. Neer II in the 1950s and has been performed by the Shoulder and Elbow Team at the University of Washington since 1975.
• Shoulder joint replacement surgery is most commonly used in individuals over the age of 50 years to treat primary glenohumeral arthritis. The outcomes in this patient group are generally excellent.
• The reported outcomes of shoulder arthroplasty in individuals under 50 years of age have been reported to be worse than those in individuals over 50 years of age.
• We found that patients under 50 years of age presenting for shoulder arthroplasty are more likely to have complex pathologies and less likely to have primary shoulder arthritis than their older counterparts.

• Knee injuries in women collegiate athletes have been consistently reported to be at least twice greater than those of men in comparable sports.
• Many of these injuries occur in situations where there is no contact with an opposing player.
• Among the most frequent injury is damage to the anterior cruciate ligament (ACL).
• A broad range of modifiable and non-modifiable factors have been implicated in the disparity in ACL injuries.
• Anatomical factors such as notch width, tibial plateau slope and size, as well as functional factors such as excessive or mistimed internal rotation and adduction have been proposed as among the potential causative factors although much uncertainty remains.
• Computer modeling can be used to simulate the effects of different structures and movements on the length of the ACL.
• Direct measurement of ligament length is possible during mechanical testing in anatomical specimens.
• Traditional mechanical testing loads a ligament along a single axis sometimes including torsion.
• Linear robots, such as those used on automobile production lines, and the more unusual parallel robots, allow accurate positioning and carefully controlled loads to be generated.
• In an orthopaedic context, robotic methods allow the accurate simulations of multiaxis functional joint movements thereby loading a ligament such as the ACL in a more realistic manner.
• New approaches to surgical reconstruction of the ACL can also be simulated using robots.
• A Musculoskeletal Robotics Laboratory is under construction at the University of Washington Medical Center.
• The UW Orthopaedics Knee Biomechanics group is a multi-disciplinary team of faculty members that is using robotics and simulation to provide insight into knee injuries and their surgical reconstruction in women.

• Osteoarthritis - the loss of the normal cartilage of a joint - is a painful, disabling disease affecting up to 40 million people in the US alone.
• When cartilage is lost, the current best treatment requires replacing the joint with artificial surfaces made of metal and plastic.
• We are investigating an approach to the regeneration of cartilage that would provide a biological treatment for osteoarthritis.
• We are exploring the concept that cartilage can be regenerated by embedding cartilagegenerating cells in engineered structures that imitate the extracellular matrix of mature cartilage.
• We created a bilayer scaffold with two pore sizes: a bone side with pore sizes of about 35 micrometers and a cartilage side with pore sizes of about 80-100 micrometers.
• We tested this construct in a rabbit model of osteoarthritis.
• Preliminary results show excellent incorporation of the new construct.
• Bioengineered joint regeneration would represent a revolution in treatment of arthritis.

• Healthy cartilage is critical for normal joint function.
• When injured or arthritic, cartilage does not heal or regenerate normal cartilage.
• Cartilage injuries are a common cause of severe disability.
• Understanding the molecular signals that regulate normal cartilage development may be a key to regenerating healthy cartilage after injury.
• We have identified a protein that appears to be critical for normal cartilage development in mice.

• In arthritis, a progressive breakdown of the collagen fibrillar network that frames cartilage leads to a loss of normal joint function since cartilage has a limited capacity to heal or regenerate.
• The current challenge in cartilage tissue-engineering is to direct chondrocytes and stem cells undergoing chondrogenesis to synthesize and deposit sufficient collagen in the extracellular matrix.
• Basic research on how the collagen fibril is assembled has led to an understanding that the type II/IX/XI collagen template is crucial for the growth and quality of the collagen fibril and consequently for an adequate amount of collagen in cartilage.
• Developing markers to monitor this assembly in normal cartilage and to assess correct assembly in tissue-engineered cartilage is a valuable and important goal.
• We seek to understand the changing quality of the cartilage collagen heteropolymer in disease or when produced as a healing or regenerative response.

• Deformities of the child’s foot are common:
• Collagen type V/XI is a quantitatively minor but indispensable polymeric template for collagen fibril formation in vertebrate tissues.
• To understand better how different collagen V/XI isoforms may modulate fibril architecture, we compared biochemically the collagen components of developing and adult bovine articular cartilage and intervertebral disc.
• With maturation of articular cartilage, the α1(V) chain progressively replaced the α2(XI) chain. A prominence of α1(V) chains is therefore characteristic and a potential biomarker of mature mammalian articular cartilage.
• A unique molecular form of type V/XI collagen is revealed in the nucleus pulposus of the intervertebral disc.
• We propose an evolving role for collagen V/XI isoforms as an adaptable template of fibril macro-architecture and hence skeletal tissue diversity.

• When a patient and a surgeon are faced with an infected total hip implant, choices must be made among different treatment options.
• We explored the perspectives of the patient and the surgeon that may contribute to the decision-making process.
• Important differences were found between patients’ and surgeons’ perceptions of risk and reward concerning health states that may arise during the treatment of an infected total hip replacement (THR).
• In general, surgeons valued quality of life, and were willing to trade quantity (length) of life in order to decrease pain and improve function.
• In general, patients valued quantity (length) of life, and were willing to trade quality of life - even if the result was living in a state of poorer function or increased pain - in order to avoid risk of death associated with an intervention.
• It is important for surgeons to be mindful of this potential difference in perspective when counseling patients about surgical and non-operative alternatives.

• Carpal tunnel syndrome is a very common disease causing numbness and tingling in the fingers.
• Ankle arthritis differs from that of the hip and knee in that it is most commonly caused by traumatic injury (rather than degeneration or inflammation) and predominantly ffects younger males.
• Ankle fusion is a well-established treatment that can improve pain but does so at a loss of motion of the ankle. It doesn’t work well when there is also arthritis in the nearby joints, because it puts extra load on these joints.
• Altered gait after ankle fusion can lead to arthritis in the surrounding small joints over time.
• The role of ankle replacement, while common in Europe, is limited in the US because of uncertainty of its effectiveness relative to ankle fusion.
• UW Medicine faculty surgeons have been treating patients with ankle replacement surgery since 1995. Initially, total ankle joint replacement was used primarily in patients who were not good candidates for fusion.
• To enable a comparison of outcomes from ankle replacement and ankle fusion we initiated a study in 2006 that compares activity and patient satisfaction after these two procedures.

• Injury to the feet of people with diabetes and neuropathy results from unperceived elevated mechanical stress.
• Once foot injuries, such as ulcers, are healed, appropriate therapeutic footwear is critical to prevent ulcer recurrence.
• Footwear design is still largely a trial-and-error process.
• In order to determine general footwear design principles, modeling offers tremendous potential since it allows exploration of a large range of conditions.
• The Finite Element Method (FEM) is a technique to model objects that can have complex shape and/or deformation characteristics by filling in the geometry with small, numerically manageable, simply shaped elements.
• Linear models are often adequate for bone but non-linear models are required to adequately describe the large deformation of soft tissues and most synthetic polymers used in footwear.
• Nonlinear analysis also allows the simulation of complex interactions between two surfaces, which can be modeled using “contact” interfaces to represent friction, and mechanical interaction between foot and footwear.
• Relatively simple 2-dimensional models can provide useful insight. For example, the advantage of molded insoles in pressure reduction at the heel can be demonstrated.
• More complex 3-dimensional models are being developed to account for the varying geometries of individual feet and for footwear options aimed at pressure relief by redistributing the plantar loads.
• The measurement of pressure between the foot and the shoe can be helpful in individual cases to see if design objectives have been achieved.
• To facilitate building patient-specific models, rapid methods of mesh generation need to be developed, and for patient-specific simulations, advanced computational techniques need to be employed.

• The poor are in danger from disasters, conflicts, and road traffic accidents, 89% of which occur in developing countries. 50 million people are injured in traffic accidents each year.
• Accident victims without surgical care spend months in crowded wards while their families who depend on them anxiously wait.
• SIGN designs, manufactures, and ships fracture implants and trains surgeons in developing countries to use them effectively and to track their results.
• Extending the regenerative power of modern fracture care enables patients in these countries to get out of bed, walk, heal, and work.