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Gates D.H.,Center for the Intrepid | Scott S.J.,U.S. Army | Wilken J.M.,Center for the Intrepid | Dingwell J.B.,University of Texas at Austin
Gait and Posture | Year: 2013

Uneven walking surfaces pose challenges to balance, especially in individuals with lower extremity amputation. The purpose of this study was to determine if lateral stability of persons with unilateral transtibial amputation (TTA) is compromised when walking on a loose rock surface. Thirteen TTA and 15 healthy controls walked over level ground and over a loose rock surface at four controlled speeds. Dependent measures, including medial-lateral center of mass (COM) motion, step width variability, lateral arm swing velocity, and mean and variability of the minimum margins of stability (MOSmin), were compared between subject groups and across conditions. TTA had greater average MOSmin than Control subjects (p=0.018). TTA exhibited decreased MOSmin on their prosthetic limbs compared to their intact limbs (p=0.036), while Control subjects did not exhibit side to side differences. Both groups increased MOSmin with increasing walking speed (p≤0.001). There was no difference in the average MOSmin between walking surfaces (p=0.724). However, the variability of MOSmin was greater on the rocks compared to level ground. Both subject groups increased step width, step width variability, COM range of motion and peak COM velocity when walking on the rock surface. TTA exhibited greater variability of both step width and MOSmin, which suggests that they made larger step-to-step corrective responses, more often, to achieve the same average result. © 2013 Elsevier B.V. Source

Tucker C.J.,U.S. Army | Wilken J.M.,Center for the Intrepid | Stinner D.J.,U.S. Army | Kirk K.L.,U.S. Army
Journal of Bone and Joint Surgery - Series A | Year: 2012

Background: While there are proponents of both bone-bridging and non-bone-bridging transtibial amputation techniques, there is a lack of evidence describing functional differences between these two techniques. The goal of the present investigation was to objectively compare the techniques of bone-bridging and non-bone-bridging with respect to limb socket displacement during physiologic loading. Methods: Fifteen male subjects with an average age of twenty-seven years (range, twenty-two to thirty-two years) who had undergone a unilateral transtibial amputation secondary to a traumatic wartime injury were prospectively evaluated. Seven patients had undergone a bone-bridging amputation, and eight had undergone a non-bone-bridging amputation. Digital fluoroscopic video was used to measure the vertical displacement of the limb within a total-surface-bearing socket with weight-bearing from 0% to 100% of body weight. Results: There was no difference in limb-socket displacement between amputation techniques with initial loading (12.78 mm for the bone-bridging group, compared with 12.43 mm for the non-bone-bridging group; p = 0.88) or with total loading (p = 0.98). Similarly, there was no difference between suspension mechanisms in limb-socket displacement with initial loading (12.15 mm for patients with pin lock suspension, compared with 12.98 mm for those with suction sleeve suspension; p = 0.72) or with total loading (18.24mmfor patients with pin lock suspension, compared with 21.42mmfor those with suction sleeve suspension, p = 0.21). Conclusions: The current study demonstrated no difference between surgical techniques with respect to bone-socket displacement. These data provide no evidence to support statements that bone-bridging contributes to a more efficient platform in the total-surface-bearing socket. Level of Evidence: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence. Copyright © 2012 by The Journal of Bone and Joint Surgery, Incorporated. Source

McAndrew P.M.,University of Texas at Austin | Dingwell J.B.,University of Texas at Austin | Wilken J.M.,Center for the Intrepid
Journal of Biomechanics | Year: 2010

Walking on uneven surfaces or while undergoing perturbations has been associated with increased gait variability in both modeling and human studies. Previous gait research involving continuous perturbations has focused on sinusoidal oscillations, which can result in individuals predicting the perturbation and/or entraining to it. Therefore, we examined the effects of continuous, pseudo-random support surface and visual field oscillations on 12 healthy, young participants. Participants walked in a virtual reality environment under no perturbation (NOP), anterior-posterior (AP) walking surface and visual oscillation and mediolateral (ML) walking surface and visual oscillation conditions. Participants exhibited shorter (p0.005), wider (p<0.001) and faster (p<0.001) steps relative to NOP during ML perturbations and shorter (p0.005) and wider (p<0.001) steps during AP perturbations. Step length variability and step width variability both increased relative to NOP during all perturbation conditions (p<0.001) but exhibited greater increases for the ML perturbations (p<0.001). Participants exhibited greater trunk position variability and trunk velocity variability in the ML direction than in the AP direction during ML perturbations relative to NOP (p<0.001). Significantly greater variability in the ML direction indicates that to maintain stability, participants needed to exert greater control in the ML direction. This observation is consistent with prior modeling predictions. The large and consistent responses observed during ML visual and walking surface perturbations suggest potential for application during gait training and patient assessment. © 2010. Source

Gates D.H.,Center for the Intrepid | Wilken J.M.,Center for the Intrepid | Scott S.J.,U.S. Army | Sinitski E.H.,Center for the Intrepid | Dingwell J.B.,University of Texas at Austin
Gait and Posture | Year: 2012

It is important to understand how people adapt their gait when walking in real-world conditions with variable surface characteristics. This study quantified lower-extremity joint kinematics, estimated whole body center of mass height (COM VT), and minimum toe clearance (MTC) while 15 healthy, young subjects walked on level ground (LG) and a destabilizing loose rock surface (RS) at four controlled speeds. There were no significant differences in average step parameters (length, time, or width) between the walking surfaces. However, the variability of these parameters increased twofold on the RS compared to LG. When walking on the RS, subjects contacted the surface with a flatter foot and increased knee and hip flexion, which enabled them to lower COM VT. Subjects exhibited increased hip and knee flexion and ankle dorsiflexion during swing on the RS. These changes contributed to a 3.8 times greater MTC on the RS compared to LG. Peak hip and knee flexion during early stance and swing increased with walking speed, contributing to decreased COM VT and increased MTC. Overall, subjects systematically adapted their movement kinematics to overcome the challenge imposed by the destabilizing loose rock surface. © 2011 Elsevier B.V. Source

Owens J.G.,Center for the Intrepid | Blair J.A.,San Antonio Military Medical Center | Patzkowski J.C.,San Antonio Military Medical Center | Blanck R.V.,Center for the Intrepid | Hsu J.R.,U.S. Army
Journal of Trauma - Injury, Infection and Critical Care | Year: 2011

Background: The ability to return to running and sports participation after lower extremity limb salvage has not been well documented previously. Although the ability to ambulate without pain or assistive devices is generally a criteria for a good limb salvage outcome, many patients at our institution have expressed a desire to return to a more athletic lifestyle to include running and sports participation. The purpose of this study was to investigate the types of athletic endeavors our high-energy lower extremity trauma patients were able to pursue after limb salvage. Methods: We retrospectively analyzed lower extremity limb salvage patients who were at least 12 weeks status after external fixation removal and participated in our limb salvage return-to-running clinical pathway. Patients were rehabilitated to their highest functional level through a sports medicine-based approach. A custom energy-storing ankle-foot orthosis was implemented to help augment plantarflexion strength in conjunction with running gait retraining. Results: The first 10 patients to complete the clinical pathway were identified. All patients were treated at the same institution by the same orthopedic surgeon and physical therapist. Eight patients have returned to running, and 10 patients have returned to weight-lifting. Seven patients have returned to cycling, three have returned to golf, three to basketball, and two to softball. Two patients have completed a mini-triathlon. Conclusion: Aggressive rehabilitation, an energy-storing ankle-foot orthosis, and running gait retraining can restore an active recreational lifestyle to patients who have undergone lower extremity limb salvage. Copyright © 2011 by Lippincott Williams & Wilkins. Source

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