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MacDonald A, Houck J, Baumhauer J. The Road to Recovery for Bunion Surgery. FOOT & ANKLE ORTHOPAEDICS 2017. [DOI: 10.1177/2473011417s000275] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Category: Bunion, Midfoot/Forefoot Introduction/Purpose: Patient reported outcomes (PROs) can provide information on individual patient’s progress throughout a treatment course and additionally, with common surgeries, powerful numbers can be generated to provide data analytic curves to provide a recovery road map for patients and surgeons. Those who deviate negatively from the predicted path may have a complication and early intervention can be initiated. Those who deviate positively have the potential to need less physical therapy, early return to sports or work. Hallux valgus (HV) is a common condition of the foot with 4.4 million patients seeking care yearly and surgery is equally common. The purpose of this study was to determine if PROMIS PROs can be used to construct data analytic curves for HV surgery. Methods: PROMIS scores were prospectively obtained from patients evaluated in a specialty foot and ankle clinic between February 2015 and November 2016. Using ICD-9/10 and CPT codes, a total of 65 patients with hallux valgus who underwent a bunionectomy by a single surgeon were identified. Those with less than two-month follow-up, multiple procedures during the follow-up period, as well as incomplete PROMIS assessment scores at any time point were excluded, resulting in 34 patients. Using a previously described method, bunionectomy-specific pre-operative cut-off values to achieve and fail to achieve minimally clinically important differences (MCID) in PF with 95% specificity and 95% sensitivity were determined. We then stratified patients based on their pre-operative PF T-scores as above or below the MCID cut-off. PF was evaluated using two-way ANOVA at 4 follow-up time periods and pre-operative cut-offs (above or below MCID cut-off) as factors to establish data analytic curves based on pre- operative scores. Results: Bunionectomy-specific PF cut-off for 95% specificity of exceeding MCID was 39.6 and 50.2 for 95% sensitivity for failing to achieve MCID. Patients were stratified based on PF T-scores above (n = 13) or below (n = 21) the MCID cut-off of 50.2. Data analytic curves were generated for above the PF cut off and below PF cut off. (Figure 1) Pairwise comparison demonstrated that those starting with a T-score above the bunionectomy specific cut-off had significantly better PF pre-operatively (p < 0.01) and again at 6-12 week follow-up (p = 0.02). There were no differences at 1 week or 3-4 week follow-up time points. Conclusion: This data confirms pre-operative PROMIS PF scores are significant post-operative predictors. While patients with pre-operative scores below the bunionectomy-specific cut-off met MCID changes in PF, their T-scores were significantly lower at 6-12wk follow-up than patients with high pre-operative T-scores. Although longer term follow-up is desirable, this short term follow up suggests a significant clinical impact of using PROMIS scores for pre-surgical decisions as well as provides a road map for recovery for patients and surgeons.
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Anderson M, Houck J, Flemister A, Baumhauer J, Ketz J, DiGiovanni B, Ciufo D, Oh I. Clinical Utilization of Patient Reported Outcome (PROMIS) Scores for Surgical Reconstruction of Posterior Tibialis Tendon Dysfunction. FOOT & ANKLE ORTHOPAEDICS 2017. [DOI: 10.1177/2473011417s000020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Category: Hindfoot Introduction/Purpose: Previous studies have demonstrated that preoperative Patient Reported Outcome Instrumentation System (PROMIS) scores effectively predict improvement in foot and ankle surgery. Adult acquired flatfoot deformity (AAFD) and Posterior Tibialis Tendon Dysfunction (PTTD) are a common surgical problem, but it is unclear if the specific thresholds for the physical function (PF), pain interference (PI) and depression published previously for all foot and ankle surgeries apply to a specific diagnosis. Furthermore, the interplay of PROMIS scores and clinical variables has not been evaluated. The purpose of this study was: 1) to investigate the change in PROMIS scales and radiographic measurements from pre- to postoperative follow up in AAFD/PTTD patients, 2) to determine if preoperative PROMIS scales predict post-surgical improvement, 3) to determine if demographic, clinical variables combined with pre-operative PROMIS scales predict post-surgical improvement. Methods: Using ICD-9/10 and CPT codes, 60 patients who underwent surgical reconstruction for AAFD/PTTD at a tertiary care center between February 2015 and November 2016 were identified. PROMIS PF, PI and Depression were assessed at initial and follow-up. A total of 35 adult patients with PROMIS scores and radiographs at baseline and greater than 3 months follow-up (mean=10.8 months) were included. For hypothesis #1, two way repeated measures ANOVAs determined pre- to post-operative change in PROMIS scales and radiographic measurements. For hypothesis #2, receiver operator curve (ROC) analysis determined the accuracy and thresholds for pre-operative decision making. For hypothesis #3, the multiple linear regression of demographic (age, gender, BMI), clinical (stage) and radiographic variables with pre-operative PROMIS scales for predicting post-operative change in PROMIS scales were evaluated (Models included: pre-operative PROMIS PF + BMI + stage AND pre-operative PROMIS PF + BMI + delta Meary’s). Results: PROMIS scales (PF(4.1), PI(-6.2) and Depression(-6.1)) and radiographic angles (lateral Meary’s (-10.8) and A/P Talo/1st metatarsal angle (-10.9) were significantly improved (p<0.01). Pre-operative PROMIS PF (AUC = 0.80±0.8, p <0.01) and PI (AUC=0.81±0.07, p<0.01) showed significant AUC for predicting Minimal Clinically Important Difference (MCID improvement in PROMIS PI. Pre-operative PROMIS Depression showed a significant AUC (0.85±0.07) for predicting MCID improvement in PROMIS Depression. However, pre-operative PROMIS PF was not predictive of MCID improvement in PROMIS PF (AUC=0.64±0.09, p=0.17). Only pre- to post-operative change in lateral Meary’s angle predicted post-operative MCID improvement for PROMIS PF (AUC of 0.85±0.08, p<0.01). The threshold for a 95% specificity/sensitivity for achieving MCID improvement in PROMIS PF was >12.5 degrees/2.5 degrees, respectively. Models combining clinical, radiographic, and PROMIS variables achieved significance (AUC > 0.81). Conclusion: PROMIS scales and radiographic angles improve significantly following surgical reconstruction of PTTD. Unlike previous studies, PROMIS PF was not predictive of improvement in PROMIS PF. However, PROMIS PF and PI were predictive of improvement in PROMIS PI. Radiographic improvement on lateral Meary’s angle was the most strongly predictive of improvement in PROMIS PF. The strongest predictor of postoperative improvement in PROMIS PF was a combination of preoperative PROMIS PF, BMI, and stage an interplay of variables not previously evaluated. Pre-operative PROMIS thresholds are effective across diagnosis, however, diagnosis specific criteria may further enhance pre-operative decisions.
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Houck J, Seidl L, Montgomery A, Keefer J, Walker M. Can Foot Exercises Alter Foot Posture, Strength, and Walking Foot Pressure Patterns in People with Severe Flat Foot? FOOT & ANKLE ORTHOPAEDICS 2017. [DOI: 10.1177/2473011417s000199] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Category: Midfoot/Forefoot, Sports Introduction/Purpose: Muscle training muscle control for barefoot running (i.e. doming seated[DS] and standing[DSt]) and post foot and ankle injury (i.e. seated plantar flexion and inversion[SPFI]) are common. Although studies demonstrated improvement in foot posture (validated foot posture index [FPI]) immediately following a 4-week exercise program this was not assessed in people with flatfoot. Also, more rigorous assessment of foot function is lacking (i.e. foot posture, strength, and plantar pressure during walking). There is clearly a need for more rigorous clinical data on the effect of foot exercises. The purpose of this pilot study was to assess the immediate effect of a 4-week exercise program on a comprehensive assessment of foot function to evaluate the potential for a more rigorous clinical trial. Methods: Eighteen individuals, 8 with a severe flatfoot (SFF), measured by FPI (> 6/12, average=8.4±0.7), age=27.8±6.9, 7 females and 1 male) and 9 age/gender matched controls (AMC) with a normal foot (FPI=0-5, average=2.2±2.0) participated. The SFF group completed 3 foot exercises (DS, DSt, SPFI) 5 days/week twice daily. The SFF group were assessed before and after 4 weeks of exercise (called weekly for exercise progression). The control participants were tested once. Testing sessions included plantar pressure during a controlled walking cadence (110 bpm) (average of 5 steps over 40 feet). Masks were applied (medial/lateral toes and forefoot, heal, midfoot) and specific variables calculated (peak pressure, percent mean pressure) during stance phase. Clinical tests included heel rise repetitions, navicular drop, and paper pull test (peak force). T-tests were used to assess the effects of pre to post in the SFF group and between the SFF group and AMC pre and post exercise. Results: Two clinical tests significantly improved from pre to post in the SFF group (heel rises increased on right = 6.1± 3.7, p<0,01, left = 7.9± 6.1, p<0.01, and navicular drop indicated less arch lowering on the right (p=0.4) and left (p=0.06)), however, the paper pull test was not significant. Lateral forefoot mask for percent total mean pressure was lower in the SSF group pre exercise versus AMC (right p=0.02, left p=0.07). However, pre to post exercise the lateral forefoot mask for peak plantar pressure increased (left p=0.014, right p=0.02) and percent of total mean pressure also increased (right p=0.04, left p = 0.07) in the SFF group. Post exercise the SFF group lateral percent total mean pressure was no longer significant compared to controls. Conclusion: This data suggests that 4 weeks of foot only exercises (no ankle exercises) improved walking (Figure 1) and increased ankle strength (heel raise ability). Previous studies have not included rigorous assessment of foot function after foot exercises. This pilot data extends previous studies by suggesting foot muscle control may directly influence foot function during walking (i.e. plantar pressure). A power analysis using this data supports the conclusions with a larger sample of approximately 20-30 people. This pilot data supports the pursuit of a more rigorous trial of the positive effect of foot exercises in patients with severe flatfoot.
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Tesche C, Houck J. P126 Spatiotemporal and task dependence of broadband aftereffects observed following parietal 10-Hz tACS: A MEG study. Clin Neurophysiol 2017. [DOI: 10.1016/j.clinph.2016.10.247] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Zoogman P, Liu X, Suleiman RM, Pennington WF, Flittner DE, Al-Saadi JA, Hilton BB, Nicks DK, Newchurch MJ, Carr JL, Janz SJ, Andraschko MR, Arola A, Baker BD, Canova BP, Chan Miller C, Cohen RC, Davis JE, Dussault ME, Edwards DP, Fishman J, Ghulam A, González Abad G, Grutter M, Herman JR, Houck J, Jacob DJ, Joiner J, Kerridge BJ, Kim J, Krotkov NA, Lamsal L, Li C, Lindfors A, Martin RV, McElroy CT, McLinden C, Natraj V, Neil DO, Nowlan CR, O'Sullivan EJ, Palmer PI, Pierce RB, Pippin MR, Saiz-Lopez A, Spurr RJD, Szykman JJ, Torres O, Veefkind JP, Veihelmann B, Wang H, Wang J, Chance K. Tropospheric Emissions: Monitoring of Pollution (TEMPO). JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER 2017; 186:17-39. [PMID: 32817995 PMCID: PMC7430511 DOI: 10.1016/j.jqsrt.2016.05.008] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
TEMPO was selected in 2012 by NASA as the first Earth Venture Instrument, for launch between 2018 and 2021. It will measure atmospheric pollution for greater North America from space using ultraviolet and visible spectroscopy. TEMPO observes from Mexico City, Cuba, and the Bahamas to the Canadian oil sands, and from the Atlantic to the Pacific, hourly and at high spatial resolution (~2.1 km N/S×4.4 km E/W at 36.5°N, 100°W). TEMPO provides a tropospheric measurement suite that includes the key elements of tropospheric air pollution chemistry, as well as contributing to carbon cycle knowledge. Measurements are made hourly from geostationary (GEO) orbit, to capture the high variability present in the diurnal cycle of emissions and chemistry that are unobservable from current low-Earth orbit (LEO) satellites that measure once per day. The small product spatial footprint resolves pollution sources at sub-urban scale. Together, this temporal and spatial resolution improves emission inventories, monitors population exposure, and enables effective emission-control strategies. TEMPO takes advantage of a commercial GEO host spacecraft to provide a modest cost mission that measures the spectra required to retrieve ozone (O3), nitrogen dioxide (NO2), sulfur dioxide (SO2), formaldehyde (H2CO), glyoxal (C2H2O2), bromine monoxide (BrO), IO (iodine monoxide),water vapor, aerosols, cloud parameters, ultraviolet radiation, and foliage properties. TEMPO thus measures the major elements, directly or by proxy, in the tropospheric O3 chemistry cycle. Multi-spectral observations provide sensitivity to O3 in the lowermost troposphere, substantially reducing uncertainty in air quality predictions. TEMPO quantifies and tracks the evolution of aerosol loading. It provides these near-real-time air quality products that will be made publicly available. TEMPO will launch at a prime time to be the North American component of the global geostationary constellation of pollution monitoring together with the European Sentinel-4 (S4) and Korean Geostationary Environment Monitoring Spectrometer (GEMS) instruments.
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DiLiberto FE, Tome J, Baumhauer JF, Houck J, Nawoczenski DA. Individual metatarsal and forefoot kinematics during walking in people with diabetes mellitus and peripheral neuropathy. Gait Posture 2015; 42:435-41. [PMID: 26253996 DOI: 10.1016/j.gaitpost.2015.07.012] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/23/2015] [Revised: 07/07/2015] [Accepted: 07/14/2015] [Indexed: 02/02/2023]
Abstract
The purpose of this study was to compare in-vivo kinematic angular excursions of individual metatarsal segments and a unified forefoot segment in people with Diabetes Mellitus and peripheral neuropathy (DMPN) without deformity or ulceration to a healthy matched control group. Thirty subjects were recruited. A five- segment foot model (1st, 3rd, and 5th metatarsals, calcaneus, tibia) was used to examine relative 3D angular excursions during the terminal stance phase of walking. Student t-tests were used to assess group differences in kinematics. Pearson correlations and cross-correlations were used to assess relationships between the motion of the individual metatarsals and the unified forefoot. Significant reductions of DMPN group sagittal plane angular excursions were detected in all individual metatarsals and the unified forefoot (p < 0.01). Frontal plane 3rd metatarsal excursion was reduced (p = 0.04) in the DMPN group. The 3rd and 5th metatarsal and the unified forefoot excursions were reduced (p ≤ 0.02) in the DMPN group in the transverse plane. In both groups, coupling of individual metatarsal and unified forefoot motion was strongest in the sagittal plane. This study illustrates that multiple individual metatarsals have reduced motion in people with DMPN. Differences in the magnitude and coupling between individual metatarsal motion and unified forefoot motion supports the use of a two segment forefoot modeling approach in future kinematic analyses. Further study is recommended to determine if the observed kinematic profile is related to the development and location of deformity and tissue breakdown in people with DMPN.
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DiLiberto FE, Tome J, Baumhauer JF, Quinn JR, Houck J, Nawoczenski DA. Multi-joint foot kinetics during walking in people with Diabetes Mellitus and peripheral neuropathy. J Biomech 2015; 48:3679-84. [DOI: 10.1016/j.jbiomech.2015.08.020] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2015] [Revised: 08/13/2015] [Accepted: 08/14/2015] [Indexed: 11/24/2022]
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Houck J, Neville C, Tome J, Flemister A. Randomized Controlled Trial Comparing Orthosis Augmented by Either Stretching or Stretching and Strengthening for Stage II Tibialis Posterior Tendon Dysfunction. Foot Ankle Int 2015; 36:1006-16. [PMID: 25857939 DOI: 10.1177/1071100715579906] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
BACKGROUND The value of strengthening and stretching exercises combined with orthosis treatment in a home-based program has not been evaluated. The purpose of this study was to compare the effects of augmenting orthosis treatment with either stretching or a combination of stretching and strengthening in participants with stage II tibialis posterior tendon dysfunction (TPTD). METHODS Participants included 39 patients with stage II TPTD who were recruited from a medical center and then randomly assigned to a strengthening or stretching treatment group. Excluding 3 dropouts, there were 19 participants in the strengthening group and 17 in the stretching group. The stretching treatment consisted of a prefabricated orthosis used in conjunction with stretching exercises. The strengthening treatment consisted of a prefabricated orthosis used in conjunction with the stretching and strengthening exercises. The main outcome measures were self-report (ie, Foot Function Index and Short Musculoskeletal Function Assessment) and isometric deep posterior compartment strength. Two-way analysis of variance was used to test for differences between groups at 6 and 12 weeks after starting the exercise programs. RESULTS Both groups significantly improved in pain and function over the 12-week trial period. The self-report measures showed minimal differences between the treatment groups. There were no differences in isometric deep posterior compartment strength. CONCLUSIONS A moderate-intensity, home-based exercise program was minimally effective in augmenting orthosis wear alone in participants with stage II TPTD. LEVEL OF EVIDENCE Level I, prospective randomized study.
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Singer S, Klejman S, Pinsker E, Houck J, Daniels T. Ankle arthroplasty and ankle arthrodesis: gait analysis compared with normal controls. J Bone Joint Surg Am 2013; 95:e191(1-10). [PMID: 24352777 DOI: 10.2106/jbjs.l.00465] [Citation(s) in RCA: 101] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
BACKGROUND This study compared patients with isolated end-stage ankle osteoarthritis, after undergoing either total ankle arthroplasty or arthrodesis, using gait analysis and patient-reported outcome measures to elucidate differences between the two treatment options, as compared with a healthy control group. METHODS Gait analyses were performed on patients with isolated ankle arthritis more than one year after undergoing either total ankle arthroplasty or arthrodesis during a ten-year period. Validated outcome questionnaire data were obtained. Seventeen patients undergoing total ankle arthroplasty, seventeen patients undergoing arthrodesis, and ten matched control subjects were included for comparison. RESULTS Patients who had undergone arthroplasty, when compared with patients who had undergone arthrodesis, demonstrated greater postoperative total sagittal plane motion (18.1° versus 13.7°; p < 0.05), dorsiflexion (11.9° versus 6.8°; p < 0.05), and range of tibial tilt (23.1° versus 19.1°; p < 0.05). Plantar flexion motion was not equivalent to normal in either group. Ankle moments and power in both treatment groups remained significantly lower compared with the control group (p < 0.05 between each treatment group and the control group for both variables). Gait patterns in both treatment groups were not completely normalized. Improvements in patient-reported Ankle Osteoarthritis Scale and Short Form-36 scores were similar for both treatment groups. CONCLUSIONS The gait patterns of patients following three-component, mobile-bearing total ankle arthroplasty more closely resembled normal gait when compared with the gait patterns of patients following arthrodesis. Dorsal motion in the sagittal plane was primarily responsible for the differences. Improvement in self-reported clinical outcome scores was similar for both groups. Further investigation is needed to determine why patients who have undergone total ankle arthroplasty do not use the plantar flexion motion in the terminal-stance phase and to explain the limited increase in power generation at toe-off after arthroplasty. Results obtained from this study may be used for future modifications of ankle prostheses and may add to clinicians' ability to inform patients of predicted functional outcomes prior to the treatment of end-stage ankle osteoarthritis.
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Wang QD, Nowak MA, Markoff SB, Baganoff FK, Nayakshin S, Yuan F, Cuadra J, Davis J, Dexter J, Fabian AC, Grosso N, Haggard D, Houck J, Ji L, Li Z, Neilsen J, Porquet D, Ripple F, Shcherbakov RV. Dissecting x-ray-emitting gas around the center of our galaxy. Science 2013; 341:981-3. [PMID: 23990554 DOI: 10.1126/science.1240755] [Citation(s) in RCA: 204] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Most supermassive black holes (SMBHs) are accreting at very low levels and are difficult to distinguish from the galaxy centers where they reside. Our own Galaxy's SMBH provides an instructive exception, and we present a close-up view of its quiescent x-ray emission based on 3 megaseconds of Chandra observations. Although the x-ray emission is elongated and aligns well with a surrounding disk of massive stars, we can rule out a concentration of low-mass coronally active stars as the origin of the emission on the basis of the lack of predicted iron (Fe) Kα emission. The extremely weak hydrogen (H)-like Fe Kα line further suggests the presence of an outflow from the accretion flow onto the SMBH. These results provide important constraints for models of the prevalent radiatively inefficient accretion state.
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Barske H, Chimenti R, Tome J, Martin E, Flemister AS, Houck J. Clinical outcomes and static and dynamic assessment of foot posture after lateral column lengthening procedure. Foot Ankle Int 2013; 34:673-83. [PMID: 23637235 DOI: 10.1177/1071100712471662] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
BACKGROUND Lateral column lengthening (LCL) has been shown to radiographically restore the medial longitudinal arch. However, the impact of LCL on foot function during gait has not been reported using validated clinical outcomes and gait analysis. METHODS Thirteen patients with a stage II flatfoot who had undergone unilateral LCL surgery and 13 matched control subjects completed self-reported pain and functional scales as well as a clinical examination. A custom force transducer was used to establish the maximum passive range of motion of first metatarsal dorsiflexion at 40 N of force. Foot kinematic data were collected during gait using 3-dimensional motion analysis techniques. RESULTS Radiographic correction of the flatfoot was achieved in all cases. Despite this, most patients continued to report pain and dysfunction postoperatively. Participants post LCL demonstrated similar passive and active movement of the medial column when we compared the operated and the nonoperated sides. However, participants post LCL demonstrated significantly greater first metatarsal passive range of motion and first metatarsal dorsiflexion during gait than did controls (P < .01 for all pairwise comparisons). CONCLUSION Patients undergoing LCL for correction of stage II adult-acquired flatfoot deformity experience mixed outcomes and similar foot kinematics as the uninvolved limb despite radiographic correction of deformity. These patients maintain a low arch posture similar to their uninvolved limb. The consequence is that first metatarsal movement operates at the end range of dorsiflexion and patients do not obtain full hindfoot inversion at push-off. Longitudinal data are necessary to make a more valid comparison of the effects of surgical correction measured using radiographs and dynamic foot posture during gait. LEVEL OF EVIDENCE Level III, comparative series.
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Neville C, Flemister AS, Houck J. Total and distributed plantar loading in subjects with stage II tibialis posterior tendon dysfunction during terminal stance. Foot Ankle Int 2013; 34:131-9. [PMID: 23386773 DOI: 10.1177/1071100712460181] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
BACKGROUND In subjects with stage II tibialis posterior tendon dysfunction (TPTD), the function of the tibialis posterior muscle is altered and may be associated with a change in total and distributed loading. METHODS Thirty subjects with a diagnosis of stage II TPTD and 15 matched control subjects volunteered to participate in a study to examine the total and distributed plantar loading under the foot during the terminal stance phase of gait. Plantar loading, measured as the subject walked barefoot, was assessed using instrumented flexible insoles. A secondary analysis was done to explore the contribution of flatfoot kinematics to plantar loading patterns. RESULTS Overall, there was reduced total plantar loading in subjects with stage II TPTD compared with controls. Accounting for differences in total loading, the presence of clinically measured weakness in subjects with TPTD was associated with reduced lateral forefoot loading. Medial longitudinal arch height was significantly correlated with loading patterns but explained only 21% of the variance in observed loading patterns. CONCLUSION Subjects with TPTD who are strong exhibited loading patterns similar to controls. Changes in total and distributed loading during terminal stance suggest there are altered ankle mechanics at push-off during the functional task of gait. CLINICAL RELEVANCE Strength, in the presence of TPTD, may be important to stabilize the midfoot during gait and might be important in rehabilitation protocols.
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Houck J, Kneiss J, Bukata SV, Puzas JE. Analysis of vertical ground reaction force variables during a Sit to Stand task in participants recovering from a hip fracture. Clin Biomech (Bristol, Avon) 2011; 26:470-6. [PMID: 21196069 PMCID: PMC3086955 DOI: 10.1016/j.clinbiomech.2010.12.004] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/31/2010] [Revised: 11/29/2010] [Accepted: 12/03/2010] [Indexed: 02/07/2023]
Abstract
BACKGROUND A Sit to Stand task following a hip fracture may be achieved through compensations (e.g. bilateral arms and uninvolved lower extremity), not restoration of movement strategies of the involved lower extremity. The primary purpose was to compare upper and lower extremity movement strategies using the vertical ground reaction force during a Sit to Stand task in participants recovering from a hip fracture to control participants. The secondary purpose was to evaluate the correlation between vertical ground reaction force variables and validated functional measures. METHODS Twenty eight community dwelling older adults, 14 who had a hip fracture and 14 control participants completed the Sit to Stand task on an instrumented chair designed to measure vertical ground reaction force, performance based tests (Timed up and go, Berg Balance Scale and Gait Speed) and a self report Lower Extremity Measure. A MANOVA was used to compare functional scales and vertical ground reaction force variables between groups. Bivariate correlations were assessed using Pearson Product Moment correlations. FINDINGS The vertical ground reaction force variables showed significantly higher bilateral arm force, higher uninvolved side peak force and asymmetry between the involved and uninvolved sides for the participants recovering from a hip fracture (Wilks' Lambda=3.16, P=0.019). Significant correlations existed between the vertical ground reaction force variables and validated functional measures. INTERPRETATION Participants recovering from a hip fracture compensated using their arms and the uninvolved side to perform a Sit to Stand. Lower extremity movement strategies captured during a Sit to Stand task were correlated to scales used to assess function, balance and falls risk.
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Flemister AS, Neville CG, Houck J. The relationship between ankle, hindfoot, and forefoot position and posterior tibial muscle excursion. Foot Ankle Int 2007; 28:448-55. [PMID: 17475139 DOI: 10.3113/fai.2007.0448] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
BACKGROUND The purpose of this study was to examine the relationship of forefoot position in the transverse plane (abduction/adduction), hindfoot position in the frontal plane (eversion/inversion), and ankle position in the sagittal plane (plantarflexion/dorsiflexion) with posterior tibialis (PT) muscle excursion using an in vitro cadaver model. METHODS Seven fresh-frozen cadaver specimens were potted and mounted on a frame. The PT tendon was dissected 15 cm proximal to the medial malleolus, and a 5-kg weight was sutured to the tendon. A six-camera motion analysis system (Optotrak, Northern Digital, Inc.) was used to track three-dimensional (3-D) motion of the tibia, calcaneus (hindfoot) and first metatarsal (forefoot) using bone pins. The ankle, hindfoot, and forefoot were manually placed in 24 different ankle and foot positions. A stepwise regression analysis was used to examine the relationship among ankle, hindfoot, and forefoot kinematics and PT muscle excursion. RESULTS Hindfoot eversion/inversion and forefoot abduction/adduction accounted for 77% of the variance in PT muscle excursion, with small contributions from ankle plantarflexion/dorsiflexion (5.7%) and forefoot plantarflexion/dorsiflexion (1.9%). A combined regression equation applied to individual specimens resulted in average errors of less than 2.5 mm. CONCLUSIONS This study supports the hypothesis that PT muscle excursion can be estimated using specific foot and ankle kinematic variables. Further, these data suggest that hindfoot eversion and forefoot abduction account for most of the variance in PT muscle excursion and are theorized to be important to control clinically altering the length of the posterior tibial muscle.
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Abstract
Acceleration of the fracture healing process would have far-reaching benefits for both civilians and military personnel. Decreasing the time to return to complete function would reduce medical costs, enhance quality of life by decreasing pain and increasing mobility, accelerate the return of professional athletes to their sport, and decrease the time for military recruits to enter active duty after injuries incurred in basic training. Moreover, augmenting the healing process may prevent the long-term disability caused by fracture nonunion. Currently available pharmaceutical agents may allow us to realize this goal. However, these agents need to be tested in prospective randomized clinical trials.
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Tome J, Nawoczenski DA, Flemister A, Houck J. Comparison of foot kinematics between subjects with posterior tibialis tendon dysfunction and healthy controls. J Orthop Sports Phys Ther 2006; 36:635-44. [PMID: 17017268 DOI: 10.2519/jospt.2006.2293] [Citation(s) in RCA: 132] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
STUDY DESIGN A 2 x 4 mixed-design ANOVA with a fixed factor of group (posterior tibialis tendon dysfunction [PTTD] and asymptomatic controls), and a repeated factor of phase of stance (loading response, midstance, terminal stance, and preswing). OBJECTIVE To compare 3-dimensional stance period kinematics (rearfoot eversion/inversion, medial longitudinal arch [MLA] angle, and forefoot abduction) of subjects with stage II PTTD to asymptomatic controls. BACKGROUND Abnormal foot postures in subjects with stage II PTTD are clinical indicators of disease progression, yet dynamic investigations of forefoot, midfoot, and rearfoot kinematic deviations in this population are lacking. METHODS Fourteen subjects with stage II PTTD were compared to 10 control subjects with normal arch index values. Subjects were matched for age, gender, and body mass index. A 5-segment, kinematic model of the leg and foot was tracked using an Optotrak Motion Analysis System. The dependent kinematic variables were rearfoot inversion/eversion, forefoot abduction/adduction, and the MLA angle. An ANOVA model was used to compare kinematic variables between groups across 4 phases of stance. RESULTS Subjects with PTTD demonstrated significantly greater rearfoot eversion (P = .042), MLA angle (P = .008) and forefoot abduction angles (P < .005) during specific phases of stance. Subjects with PTTD demonstrated significantly greater rearfoot eversion (P<.004) and MLA angles (P < .009) by 6.2 degrees and 8.0 degrees, respectively, during loading response when compared to controls. During preswing, the subjects with PTTD demonstrated a significantly greater MLA angle (P < .002) and a forefoot abduction angle (P<.001) which exceeded that of the controls by 10.0 degrees. CONCLUSIONS The abnormal kinematics observed at the rearfoot, midfoot, and forefoot across all phases of stance implicate a failure of compensatory muscle and secondary ligamentous support to control foot kinematics in subjects with stage II PTTD.
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Gushue DL, Houck J, Lerner AL. Effects of childhood obesity on three-dimensional knee joint biomechanics during walking. J Pediatr Orthop 2006; 25:763-8. [PMID: 16294133 DOI: 10.1097/01.bpo.0000176163.17098.f4] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Despite the increasing percentages of children who are overweight, few studies have investigated their gait patterns. The purpose of this study was to quantify the three-dimensional knee joint kinematics and kinetics during walking in children of varying body mass and to identify effects associated with obesity. Three-dimensional kinematics and kinetics were collected from children of normal weight and overweight during normal gait using surface-mounted infrared emitting diodes and a force plate. The overweight group walked with a significantly lower peak knee flexion angle during early stance, and no significant differences in peak internal knee extension moments were found between groups. However, the overweight group showed a significantly higher peak internal knee abduction moment during early stance. These data suggest that although overweight children may develop a gait adaptation to maintain a similar knee extensor load, they may not be able to compensate for alterations in the frontal plane, which may lead to increased medial compartment joint loads. Therefore, assuming that the development of varus angular deformities of the knee joint and, in the longer term, medial compartment osteoarthritis are influenced by cumulative stress, this study supports the understanding that childhood obesity may impart a greater risk for the development of these diseases.
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Gushue DL, Houck J, Lerner AL. Rabbit knee joint biomechanics: motion analysis and modeling of forces during hopping. J Orthop Res 2005; 23:735-42. [PMID: 16022984 DOI: 10.1016/j.orthres.2005.01.005] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Revised: 12/22/2004] [Accepted: 12/22/2004] [Indexed: 02/04/2023]
Abstract
Although the rabbit hindlimb has been commonly used as an experimental animal model for studies of osteoarthritis, bone growth and fracture healing, the in vivo biomechanics of the rabbit knee joint have not been quantified. The purpose of this study was to investigate the kinematic and kinetic patterns during hopping of the adult rabbit, and to develop a model to estimate the joint contact force distribution between the tibial plateaus. Force platform data and three-dimensional motion analysis using infrared markers mounted on intracortical bone pins were combined to calculate the knee and ankle joint intersegmental forces and moments. A statically determinate model was developed to predict muscle, ligament and tibiofemoral joint contact forces during the stance phase of hopping. Variations in hindlimb kinematics permitted the identification of two landing patterns, that could be distinguished by variations in the magnitude of the external knee abduction moment. During hopping, the prevalence of an external abduction moment led to the prediction of higher joint contact forces passing through the lateral compartment as compared to the medial compartment of the knee joint. These results represent critical data on the in vivo biomechanics of the rabbit knee joint, which allow for comparisons to both other experimental animal models and the human knee, and may provide further insight into the relationships between mechanical loading, osteoarthritis, bone growth, and fracture healing.
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Houck J, Yack HJ, Cuddeford T. Validity and comparisons of tibiofemoral orientations and displacement using a femoral tracking device during early to mid stance of walking. Gait Posture 2004; 19:76-84. [PMID: 14741306 DOI: 10.1016/s0966-6362(03)00033-x] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
First, this study compares tibiofemoral motion during walking using a new femoral tracking device (FTD) and bone mounted markers in a single subject (n=1). The results suggest errors of <3 degrees in tibiofemoral angles using the FTD method over the first 85% of stance. Second, this study compares tibiofemoral angles and displacement during walking using the FTD method and a modified Helen Hayes method to track the femur in 13 subjects (n=13). The results suggest similar tibiofemoral angles in the sagittal and frontal planes using the two methods (average root mean square (RMS) differences <3.6+/-1.5 degrees ), and a large decrease in the transverse plane angles (average RMS differences=6.5+/-1.9 degrees ) and estimates of tibiofemoral displacement (P<0.05) using the FTD method. The FTD method presents a practical alternative to recording tibiofemoral transverse plane angles and displacement over the first 85% of stance.
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Houck J. Muscle activation patterns of selected lower extremity muscles during stepping and cutting tasks. J Electromyogr Kinesiol 2003; 13:545-54. [PMID: 14573369 DOI: 10.1016/s1050-6411(03)00056-7] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Lower extremity muscle activations during crossover and side step cut tasks are hypothesized to play an important role in controlling knee motion, and therefore, impact the design of knee injury prevention and rehabilitation programs. However, the contribution of lower extremity muscles to frontal and transverse plane moments during cutting tasks is unclear. The purpose of this study was to compare the muscle activation patterns of selected lower extremity muscles (vastus lateralis, medial/lateral hamstrings and medial/lateral gastrocnemius) of subjects performing a stepping down and side step cut, a stepping down and crossover cut and an equivalent straight ahead task. Ground reaction force was used to determine the cut angle, stance time and compare the lower limb loading during each task. Electromyography data during all tasks were normalized to the average activation during the straight ahead tasks to determine relative changes in muscle activation between the straight ahead and different cut styles (crossover and side step). There were no differences in the pattern of muscle activation of the vastus lateralis, or lateral hamstring muscles when comparing the cutting tasks to the equivalent straight ahead task. However, the crossover cut task resulted in significantly higher muscle activation of the medial hamstrings and lateral gastrocnemius muscles relative to both the side step cut and straight ahead tasks. These results suggest the medial/lateral hamstrings and medial/lateral gastrocnemius play a role in transverse and frontal plane control during cut tasks.
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Houck J, Yack HJ. Associations of knee angles, moments and function among subjects that are healthy and anterior cruciate ligament deficient (ACLD) during straight ahead and crossover cutting activities. Gait Posture 2003; 18:126-38. [PMID: 12855308 DOI: 10.1016/s0966-6362(02)00188-1] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The objective of this study was to compare knee angles and moments of healthy subjects (n=20) and subjects that were anterior cruciate ligament deficient (ACLD) (n=16) during stepping and crossover cutting activities. Subjects that were ACLD were separated into high (n=7) and low (n=9) functioning groups based on knee functional ratings. Knee angles and moments were estimated using three dimensional motion tracking and force plate data. The results suggest that knee angle and moment data were associated with level of functioning of ACLD subjects. Primarily knee frontal and transverse plane moments distinguished the stepping and crossover cut activities. Only some of the findings for the ACLD group were attributed to increasing knee stability.
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Houck J, Lerner A, Gushue D, Yack HJ. Self-reported giving-way episode during a stepping-down task: case report of a subject with an ACL-deficient knee. J Orthop Sports Phys Ther 2003; 33:273-82; discussion 283-6. [PMID: 12775001 DOI: 10.2519/jospt.2003.33.5.273] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
STUDY DESIGN Case report. OBJECTIVE To describe the knee kinematics and moments of a giving-way trial of a subject with an anterior-cruciate-ligament- (ACL) deficient knee relative to his non-giving-way trials and to healthy subjects during a step-down task. BACKGROUND Episodes of giving way are believed to damage joint structures, therefore treatments aim to prevent giving-way episodes, yet few studies document giving-way events. METHODS The giving-way trial experienced by a 32-year-old male subject with ACL deficiency during a step-down task was compared to his non-giving-way trials (n = 5) and data from healthy subjects (n = 20). Position data collected at 60 Hz were combined with anthropometric data and ground reaction force data collected at 300 Hz to estimate knee displacement and 3-dimensional angles and net joint moments. RESULTS The knee joint displacement was higher during the giving-way trial: from 4% to 32% of stance, reaching 9.0 mm at 18% of stance as compared to 1.6 +/- 0.7 mm for the non-giving-way trials. After 4% of stance, the knee flexion angle of the giving-way trial was 6.6 degrees higher than the non-giving-way trials and was associated with a higher knee extension moment. The knee frontal plane moment was near neutral during early stance of the giving-way trial in contrast to the non-giving way and healthy subjects which demonstrated a knee abduction moment. CONCLUSIONS The response of this subject to the giving-way event suggests that higher knee flexion angles may enhance knee stability and, in reaction to the giving-way event, that knee extension moment may increase.
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Bilodeau M, Houck J, Cuddeford T, Sharma S, Riley N. Variations in the relationship between the frequency content of EMG signals and the rate of torque development in voluntary and elicited contractions. J Electromyogr Kinesiol 2002; 12:137-45. [PMID: 11955986 DOI: 10.1016/s1050-6411(02)00012-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
Abstract
Our purpose was to characterize the relationship between EMG mean power frequency (MPF) or median frequency (MF) and rate of torque development in voluntary ballistic and electrically elicited isometric contractions. Twenty-three healthy adults participated in two sets of experiments performed on elbow flexor muscles. For Experiment 1, subjects were asked to generate voluntary ballistic contractions by reaching four different target torque levels (20, 40, 60 and 100% of the maximal voluntary contraction (MVC)) as fast as they could. For Experiment 2, electrical (M-waves) and mechanical (twitches) responses to electrical stimulation of the nerves supplying the biceps brachii and brachioradialis muscles were recorded with the subjects at rest and with a background isometric contraction of 15% MVC. MPF, MF and rate of torque development (% MVC/s) were calculated for both voluntary and elicited contractions. Significant positive correlations were observed between MPF and rate of torque development for the voluntary contractions, whereas significant negative correlations were observed between the two variables for elicited contractions. This suggests that factors other than muscle fiber composition influence the frequency content of EMG signals and/or the rate of torque development, and that the effect of these factors will vary between voluntary and elicited contractions.
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Houck J, Yack HJ. Giving way event during a combined stepping and crossover cutting task in an individual with anterior cruciate ligament deficiency. J Orthop Sports Phys Ther 2001; 31:481-9; discusssion 490-5. [PMID: 11570732 DOI: 10.2519/jospt.2001.31.9.481] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
STUDY DESIGN Case study. OBJECTIVE To compare knee kinematics and moments of nongiving way trials to a giving way trial during a combined stepping and crossover cutting activity. BACKGROUND The knee kinematics and moments associated with giving way episodes suggest motor control strategies that lead to instability and recovery of stability during movement. METHODS AND MEASURES A 27-year-old woman with anterior cruciate ligament deficiency reported giving way while performing a combined stepping and crossover cutting activity. A motion analysis system recorded motion of the pelvis, femur, tibia, and foot using 3 infrared emitting diodes placed on each segment at 60 Hz. Force plate recordings at 300 Hz were combined with limb inertial properties and position data to estimate net knee joint moments. The stance time, foot progression angle, and cutting angle were also included to evaluate performance between trials. RESULTS Knee internal rotation during the giving way trial increased 3.2 degrees at 54% of stance relative to the nongiving way trials. Knee flexion during the giving way trial increased to 33.1 degrees at 66% of stance, and the knee moment switched from a nominal flexor moment to a knee extensor moment at 64% of stance. The knee abductor moment and external rotation moment during the giving way trial deviated in early stance. CONCLUSIONS The observed response to the giving way event suggests that increasing knee flexion may enhance knee stability for this subject. The transverse and frontal plane moments appear important in contributing to the giving way event. Further research that assists clinicians in understanding how interventions can impact control of movements in these planes is necessary.
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Venter JC, Adams MD, Myers EW, Li PW, Mural RJ, Sutton GG, Smith HO, Yandell M, Evans CA, Holt RA, Gocayne JD, Amanatides P, Ballew RM, Huson DH, Wortman JR, Zhang Q, Kodira CD, Zheng XH, Chen L, Skupski M, Subramanian G, Thomas PD, Zhang J, Gabor Miklos GL, Nelson C, Broder S, Clark AG, Nadeau J, McKusick VA, Zinder N, Levine AJ, Roberts RJ, Simon M, Slayman C, Hunkapiller M, Bolanos R, Delcher A, Dew I, Fasulo D, Flanigan M, Florea L, Halpern A, Hannenhalli S, Kravitz S, Levy S, Mobarry C, Reinert K, Remington K, Abu-Threideh J, Beasley E, Biddick K, Bonazzi V, Brandon R, Cargill M, Chandramouliswaran I, Charlab R, Chaturvedi K, Deng Z, Di Francesco V, Dunn P, Eilbeck K, Evangelista C, Gabrielian AE, Gan W, Ge W, Gong F, Gu Z, Guan P, Heiman TJ, Higgins ME, Ji RR, Ke Z, Ketchum KA, Lai Z, Lei Y, Li Z, Li J, Liang Y, Lin X, Lu F, Merkulov GV, Milshina N, Moore HM, Naik AK, Narayan VA, Neelam B, Nusskern D, Rusch DB, Salzberg S, Shao W, Shue B, Sun J, Wang Z, Wang A, Wang X, Wang J, Wei M, Wides R, Xiao C, Yan C, Yao A, Ye J, Zhan M, Zhang W, Zhang H, Zhao Q, Zheng L, Zhong F, Zhong W, Zhu S, Zhao S, Gilbert D, Baumhueter S, Spier G, Carter C, Cravchik A, Woodage T, Ali F, An H, Awe A, Baldwin D, Baden H, Barnstead M, Barrow I, Beeson K, Busam D, Carver A, Center A, Cheng ML, Curry L, Danaher S, Davenport L, Desilets R, Dietz S, Dodson K, Doup L, Ferriera S, Garg N, Gluecksmann A, Hart B, Haynes J, Haynes C, Heiner C, Hladun S, Hostin D, Houck J, Howland T, Ibegwam C, Johnson J, Kalush F, Kline L, Koduru S, Love A, Mann F, May D, McCawley S, McIntosh T, McMullen I, Moy M, Moy L, Murphy B, Nelson K, Pfannkoch C, Pratts E, Puri V, Qureshi H, Reardon M, Rodriguez R, Rogers YH, Romblad D, Ruhfel B, Scott R, Sitter C, Smallwood M, Stewart E, Strong R, Suh E, Thomas R, Tint NN, Tse S, Vech C, Wang G, Wetter J, Williams S, Williams M, Windsor S, Winn-Deen E, Wolfe K, Zaveri J, Zaveri K, Abril JF, Guigó R, Campbell MJ, Sjolander KV, Karlak B, Kejariwal A, Mi H, Lazareva B, Hatton T, Narechania A, Diemer K, Muruganujan A, Guo N, Sato S, Bafna V, Istrail S, Lippert R, Schwartz R, Walenz B, Yooseph S, Allen D, Basu A, Baxendale J, Blick L, Caminha M, Carnes-Stine J, Caulk P, Chiang YH, Coyne M, Dahlke C, Deslattes Mays A, Dombroski M, Donnelly M, Ely D, Esparham S, Fosler C, Gire H, Glanowski S, Glasser K, Glodek A, Gorokhov M, Graham K, Gropman B, Harris M, Heil J, Henderson S, Hoover J, Jennings D, Jordan C, Jordan J, Kasha J, Kagan L, Kraft C, Levitsky A, Lewis M, Liu X, Lopez J, Ma D, Majoros W, McDaniel J, Murphy S, Newman M, Nguyen T, Nguyen N, Nodell M, Pan S, Peck J, Peterson M, Rowe W, Sanders R, Scott J, Simpson M, Smith T, Sprague A, Stockwell T, Turner R, Venter E, Wang M, Wen M, Wu D, Wu M, Xia A, Zandieh A, Zhu X. The sequence of the human genome. Science 2001; 291:1304-51. [PMID: 11181995 DOI: 10.1126/science.1058040] [Citation(s) in RCA: 7685] [Impact Index Per Article: 334.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
A 2.91-billion base pair (bp) consensus sequence of the euchromatic portion of the human genome was generated by the whole-genome shotgun sequencing method. The 14.8-billion bp DNA sequence was generated over 9 months from 27,271,853 high-quality sequence reads (5.11-fold coverage of the genome) from both ends of plasmid clones made from the DNA of five individuals. Two assembly strategies-a whole-genome assembly and a regional chromosome assembly-were used, each combining sequence data from Celera and the publicly funded genome effort. The public data were shredded into 550-bp segments to create a 2.9-fold coverage of those genome regions that had been sequenced, without including biases inherent in the cloning and assembly procedure used by the publicly funded group. This brought the effective coverage in the assemblies to eightfold, reducing the number and size of gaps in the final assembly over what would be obtained with 5.11-fold coverage. The two assembly strategies yielded very similar results that largely agree with independent mapping data. The assemblies effectively cover the euchromatic regions of the human chromosomes. More than 90% of the genome is in scaffold assemblies of 100,000 bp or more, and 25% of the genome is in scaffolds of 10 million bp or larger. Analysis of the genome sequence revealed 26,588 protein-encoding transcripts for which there was strong corroborating evidence and an additional approximately 12,000 computationally derived genes with mouse matches or other weak supporting evidence. Although gene-dense clusters are obvious, almost half the genes are dispersed in low G+C sequence separated by large tracts of apparently noncoding sequence. Only 1.1% of the genome is spanned by exons, whereas 24% is in introns, with 75% of the genome being intergenic DNA. Duplications of segmental blocks, ranging in size up to chromosomal lengths, are abundant throughout the genome and reveal a complex evolutionary history. Comparative genomic analysis indicates vertebrate expansions of genes associated with neuronal function, with tissue-specific developmental regulation, and with the hemostasis and immune systems. DNA sequence comparisons between the consensus sequence and publicly funded genome data provided locations of 2.1 million single-nucleotide polymorphisms (SNPs). A random pair of human haploid genomes differed at a rate of 1 bp per 1250 on average, but there was marked heterogeneity in the level of polymorphism across the genome. Less than 1% of all SNPs resulted in variation in proteins, but the task of determining which SNPs have functional consequences remains an open challenge.
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