Slocum Center for Orthopedics and Sports Medicine

Eugene, OR, United States

Slocum Center for Orthopedics and Sports Medicine

Eugene, OR, United States

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Howell D.R.,University of Oregon | Osternig L.R.,University of Oregon | Koester M.C.,Slocum Center for Orthopedics and Sports Medicine | Chou L.-S.,University of Oregon
Experimental Brain Research | Year: 2014

Concussion has been reported to result in disturbances to motor and cognitive functions. One way to examine these disturbances is through a dual-task assessment. Many secondary cognitive tasks have been proposed as appropriate tools during concussion assessment; however, task complexity has not been compared within a dual-task investigation. The purpose of this study was to prospectively examine how gait balance control was affected by three secondary cognitive tasks of varying complexity following concussion. Forty-six adolescents completed a dual-task walking protocol which included walking without any cognitive task (WALK), walking while completing a single auditory Stroop (SAS), multiple auditory Stroop (MAS), and a question and answer task (Q&A). Those who sustained a concussion (n = 23, mean age 15.4 ± 1.3 years) reported to the laboratory within 72 h of injury and in the following time increments: 1 week, 2 weeks, 1 month, and 2 months post-injury. Twenty-three healthy control subjects (mean age 15.4 ± 1.3 years), individually matched to each concussion subject, completed the same protocol in similar time increments. The concussion group demonstrated greater total center of mass (COM) medial/lateral displacement in the MAS and Q&A conditions compared with the control group. The concussion group also displayed the greatest peak COM anterior velocity in the least complex condition (WALK), and a significant decrease was observed as task complexity increased (SAS > MAS > Q&A). These findings indicate that gait balance control may be affected by task complexity following concussion and represent a way to identify motor recovery following concussion. © 2014 Springer-Verlag.


Bailey A.N.,University of Oregon | Hocker A.D.,University of Oregon | Vermillion B.R.,University of Oregon | Smolkowski K.,Oregon Research Institute | And 3 more authors.
American Journal of Physiology - Regulatory Integrative and Comparative Physiology | Year: 2012

Total knee arthroplasty (TKA) is the most common and a cost-effective surgical remediation for older adults with long-standing osteoarthritis. In parallel with the expanding population of older adults, the number of TKAs performed annually is projected to be 3.48 million by 2030. During this surgery, a tourniquet is used to stop blood flow to the operative leg. However, the molecular pathways that are affected by tourniquet use during TKA continue to be elucidated. We hypothesized that components of the catabolic FoxO3a (i.e., MuRF1, MAFbx, and Bnip3) pathway, as well as the cellular stress pathways [i.e., stress-activated protein kinase (SAPK)/JNK and MAPKs], are upregulated during TKA. The purpose of this study was to measure changes in transcripts and proteins involved in muscle cell catabolic and stress-activated pathways. We obtained muscle biopsies from subjects, 70 ± 1.3 yr, during TKA, from the vastus lateralis at baseline (before tourniquet inflation), during maximal ischemia (just before tourniquet release), and during reperfusion. Total tourniquet time was 43 ± 2 min and reperfusion time was 16 ± 1. Significant increases in FoxO3a downstream targets, MAFbx and MuRF1, were present for mRNA levels during ischemia (MAFbx, P = 0.04; MuRF1, P = 0.04), and protein expression during ischemia (MAFbx, P = 0.002; MuRF1, P = 0.001) and reperfusion (MuRF1, P = 0.002). Additionally, stress-activated JNK gene expression (P = 0.01) and protein were elevated during ischemia (P = 0.001). The results of this study support our hypothesis that protein degradation pathways are stimulated during TKA. Muscle protein catabolism is likely to play a role in the rapid loss of muscle volume measured within 2 wk of this surgery. © 2012 the American Physiological Society.


Becker J.,University of Oregon | Pisciotta E.,University of Oregon | James S.,Slocum Center for Orthopedics and Sports Medicine | Osternig L.R.,University of Oregon | Chou L.-S.,University of Oregon
Gait and Posture | Year: 2014

This study examined differences in center of pressure (COP) trajectories between shod and barefoot running. Ten habitually shod runners ran continuous laps under both shod and barefoot conditions. The COP trajectory was calculated in the global coordinate system but then transformed to the anatomic coordinate system of the foot. The anterior-posterior and medio-lateral positions and excursions of the COP, as well as the most medial location and percent stand at which it occurred were examined. Additionally, external eversion moments and ground reaction forces were assessed. Compared to the shod condition, in the barefoot condition the COP was located more anteriorly early in stance and the COP was located significantly more medially at most time points across stance. There were no differences in external eversion moments during early stance or peak ground reaction forces between conditions. Future studies on mechanical or epidemiological differences between shod and barefoot running may find the COP trajectory an informative parameter to examine. © 2014 Elsevier B.V.


Bee C.R.,Oregon Health And Science University | Sheerin D.V.,Slocum Center for Orthopedics and Sports Medicine | Wuest T.K.,Slocum Center for Orthopedics and Sports Medicine | Fitzpatrick D.C.,Slocum Center for Orthopedics and Sports Medicine
Journal of Orthopaedic Trauma | Year: 2013

OBJECTIVE: To determine the incidence of vitamin D deficiency in orthopaedic trauma patients undergoing fracture surgery living in the Northwest United States. DESIGN: Retrospective observational cohort study. SETTING: Level 2 trauma center. PATIENTS: Two cohorts of patients undergoing fracture repair surgery during a 3-month period in winter and summer had serum vitamin D levels drawn at the time of surgery. One hundred three patients were reviewed in the winter cohort and 98 in the summer cohort. MAIN OUTCOME MEASURE: Serum 25(OH) vitamin D levels of patients undergoing fracture repair surgery. RESULTS: Normal levels of vitamin D were considered to be between 32 and 80 ng/mL. Most patients in both cohorts were vitamin D insufficient. The average level for the winter cohort was 26.4 ng/mL, which was significantly lower than the average level for the summer cohort, 29.8 ng/mL (P = 0.03). CONCLUSIONS: A high incidence of vitamin D insufficiency and deficiency likely exists across all age groups in orthopaedic trauma patients living in the Northwest United States and regions with similarly northern latitude. Further study is required to confirm improved fracture healing with normalization of serum vitamin D levels. LEVEL OF EVIDENCE: Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence. Copyright © 2013 by Lippincott Williams & Wilkins.


Paterson W.H.,University of Memphis | Throckmorton T.W.,University of Memphis | Koester M.,Slocum Center for Orthopedics and Sports Medicine | Azar F.M.,University of Memphis | Kuhn J.E.,Vanderbilt University
Journal of Bone and Joint Surgery - Series A | Year: 2010

Background: Immobilization after closed reduction has long been the standard treatment for primary anterior dislocation of the shoulder. To determine the optimum duration and position of immobilization to prevent recurrent dislocation, a systematic review of the relevant literature was conducted. Methods: Of 2083 published studies that were identified by means of a literature review, nine Level-I and Level-II studies were systematically reviewed. The outcome of interest was recurrent dislocation. Additional calculations were performed by pooling data to identify the ideal length and position (external or internal rotation) of immobilization. Results: Six studies (including five Level-I studies and one Level-II study) evaluated the use of immobilization in internal rotation for varying lengths of time. Pooled data analysis of patients younger than thirty years old demonstrated that the rate of recurrent instability was 41% (forty of ninety-seven) in patients who had been immobilized for one week or less and 37% (thirty-four of ninety-three) in patients who had been immobilized for three weeks or longer (p = 0.52). An age of less than thirty years at the time of the index dislocation was significantly predictive of recurrence in most studies. Three studies (including one Level-I and two Level-II studies) compared recurrence rates with immobilization in external and internal rotation. Analysis of the pooled data demonstrated that the rate of recurrence was 40% (twenty-five of sixty-three) for patients managed with conventional sling immobilization in internal rotation and 25% (twenty-two of eighty-eight) for those managed with bracing in external rotation (p = 0.07). Conclusions: Analysis of the best available evidence indicates there is no benefit of conventional sling immobilization for longer than one week for the treatment of primary anterior shoulder dislocation in younger patients. An age of less than thirty years at the time of injury is significantly predictive of recurrence. Bracing in external rotation may provide a clinically important benefit over traditional sling immobilization, but the difference in recurrence rates did not achieve significance with the numbers available. Level of Evidence: Therapeutic Level II. See Instructions to Authors for a complete description of levels of evidence. Copyright © 2010 by The Journal of Bone and Joint Surgery, Incorporated.


Hak D.J.,University of Colorado at Denver | Fitzpatrick D.,Slocum Center for Orthopedics and Sports Medicine | Bishop J.A.,Stanford University | Marsh J.L.,University of Iowa | And 4 more authors.
Injury | Year: 2014

Fracture healing is a critically important clinical event for fracture patients and for clinicians who take care of them. The clinical evaluation of fracture healing is based on both radiographic findings and clinical findings. Risk factors for delayed union and nonunion include patient dependent factors such as advanced age, medical comorbidities, smoking, non-steroidal anti-inflammatory use, various genetic disorders, metabolic disease and nutritional deficiency. Patient independent factors include fracture pattern, location, and displacement, severity of soft tissue injury, degree of bone loss, quality of surgical treatment and presence of infection. Established nonunions can be characterised in terms of biologic capacity, deformity, presence or absence of infection, and host status. Hypertrophic, oligotrophic and atrophic radiographic appearances allow the clinician to make inferences about the degree of fracture stability and the biologic viability of the fracture fragments while developing a treatment plan. Non-unions are difficult to treat and have a high financial impact. Indirect costs, such as productivity losses, are the key driver for the overall costs in fracture and non-union patients. Therefore, all strategies that help to reduce healing time with faster resumption of work and activities not only improve medical outcome for the patient, they also help reduce the financial burden in fracture and non-union patients. © 2014 Elsevier Ltd.


Tsai S.,Legacy Research and Technology Center | Fitzpatrick D.C.,Slocum Center for Orthopedics and Sports Medicine | Madey S.M.,Legacy Research and Technology Center | Bottlang M.,Legacy Research and Technology Center
Journal of Orthopaedic Research | Year: 2015

Axial dynamization of an osteosynthesis construct can promote fracture healing. This biomechanical study evaluated a novel dynamic locking plate that derives symmetric axial dynamization by elastic suspension of locking holes within the plate. Standard locked and dynamic plating constructs were tested in a diaphyseal bridge-plating model of the femoral diaphysis to determine the amount and symmetry of interfragmentary motion under axial loading, and to assess construct stiffness under axial loading, torsion, and bending. Subsequently, constructs were loaded until failure to determine construct strength and failure modes. Finally, strength tests were repeated in osteoporotic bone surrogates. One body-weight axial loading of standard locked constructs produced asymmetric interfragmentary motion that was over three times smaller at the near cortex (0.1±0.01) than at the far cortex (0.32±0.02). Compared to standard locked constructs, dynamic plating constructs enhanced motion by 0.32 at the near cortex and by 0.33 at the far cortex and yielded a 77% lower axial stiffness (p<0.001). Dynamic plating constructs were at least as strong as standard locked constructs under all test conditions. In conclusion, dynamic locking plates symmetrically enhance interfragmentary motion, deliver controlled axial dynamization, and are at least comparable in strength to standard locked constructs. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 33:1218-1225, 2015.


Doornink J.,Legacy Research and Technology Center | Fitzpatrick D.C.,Slocum Center for Orthopedics and Sports Medicine | Madey S.M.,Legacy Research and Technology Center | Bottlang M.,Legacy Research and Technology Center
Journal of Orthopaedic Trauma | Year: 2011

The high stiffness of periarticular locked plating constructs can suppress callus formation and fracture healing. Replacing standard locking screws with far cortical locking (FCL) screws can decrease construct stiffness and can improve fracture healing in diaphyseal plating constructs. However, FCL function has not been tested in conjunction with periarticular plating constructs in which FCL screws are confined to the diaphyseal segment. This biomechanical study evaluated if diaphyseal fixation of a periarticular locking plate with FCL screws reduces construct stiffness and induces parallel interfragmentary motion without decreasing construct strength. Periarticular locking plates were applied to stabilize distal femur fractures in 22 paired femurs using either a standard locked plating approach (LP group) or FCL for diaphyseal fixation (FCL group) using MotionLoc screws (Zimmer, Warsaw, IN). Each specimen was evaluated under quasiphysiological loading to assess construct stiffness, construct durability under dynamic loading, and residual strength after dynamic loading. FCL constructs had an 81% lower initial stiffness than LP constructs. They induced nearly five times more interfragmentary motion than LP constructs under one body weight loading (P < 0.001). FCL constructs generated parallel interfragmentary motion, whereas LP constructs exhibited 48% less motion at the near cortex than at the far cortex (P = 0.002). Seven LP constructs and eight FCL constructs survived 100,000 loading cycles. The residual strength of surviving constructs was 4.9 ± 1.6 kN (LP group) and 5.3 ± 1.1 kN (FCL group, P = 0.73). In summary, FCL screws reduce stiffness, generate parallel interfragmentary motion, and retain the strength of a periarticular locked plating construct. Therefore, FCL fixation may be advisable for stiffness reduction of periarticular plating constructs to promote fracture healing by callus formation. Copyright © 2011 by Lippincott Williams & Wilkins.


Lujan T.J.,Legacy Research and Technology Center | Madey S.M.,Legacy Research and Technology Center | Fitzpatrick D.C.,Slocum Center for Orthopedics and Sports Medicine | Byrd G.D.,Legacy Research and Technology Center | And 2 more authors.
Journal of Biomechanics | Year: 2010

Callus formation occurs in the presence of secondary bone healing and has relevance to the fracture's mechanical environment. An objective image processing algorithm was developed to standardize the quantitative measurement of periosteal callus area in plain radiographs of long bone fractures. Algorithm accuracy and sensitivity were evaluated using surrogate models. For algorithm validation, callus formation on clinical radiographs was measured manually by orthopaedic surgeons and compared to non-clinicians using the algorithm. The algorithm measured the projected area of surrogate calluses with less than 5% error. However, error will increase when analyzing very small areas of callus and when using radiographs with low image resolution (i.e. 100 pixels per inch). The callus size extracted by the algorithm correlated well to the callus size outlined by the surgeons (R 2=0.94, p<0.001). Furthermore, compared to clinician results, the algorithm yielded results with five times less inter-observer variance. This computational technique provides a reliable and efficient method to quantify secondary bone healing response. © 2009 Elsevier Ltd.


To evaluate the clinical performance of the Dynamic Helical Hip System (DHHS) spiral blade relative to the Dynamic Hip Screw (DHS) lag screw. Randomized prospective study. One level-2 trauma center and one level-3 trauma center. Fifty-one consecutive patients were recruited into the trial. Inclusion criteria included patients over 50 years of age with AO/OTA 31A1 or 31A2 fracture. Surgeries were performed by one of 15 participating community orthopaedic surgeons. The patients were randomized to either a DHHS or DHS implant. Follow-up occurred at two weeks and six weeks and then at six-week intervals until healing occurred. Primary outcome variables included sliding of die implant on the final AP radiographs, failure by cut-out and implant failure. There were 24 patients in the DHS group and 27 in the DHHS group. There was no difference in age, gender, ASA score, fracture classification or in the quality of reduction measured on the immediate postoperative radiographs (p=0.28) between the two groups. The tip apex distance was 18.7 mm in the DHHS group and 18.5 mm in the DHS group (p=0.40). The DHHS group had average blade sliding of 7.4 mm while the DHS group had an average lag-screw sliding of 7.7 (p=0.45). The DHHS group had two failures by central protrusion of the blade through the femoral head without significant varus collapse or superior migration. One was revised to a DHS and healed, the other was revised to a proximal femoral locking plate, which also failed and eventually required revision to a total hip arthroplasty. Investigation of the implants post failure showed evidence of binding of the blade shaft in the barrel as a mechanism of failure in both cases. No DHS implants cut out in this series, although one patient was revised to a total hip arthroplasty for symptomatic segmental osteonecrosis. Both implants performed well in a majority of cases. The higher incidence of failure in the DHHS group is concerning, despite the low numbers. The mechanism of failure of the DHHS implant left adequate bone stock for attempts at revision fixation.

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