Gait analysis parameters of healthy human subjects with asymmetric loads.

This article focuses on the analysis of gait parameters, ground reaction forces (GRF), and motion signals, for the various asymmetric loads carried by healthy human subjects during walking. Eight asymptomatic human volunteers were enrolled in this study. They were asked to walk, at self-selected pace, with various weights ranging from 0 to 11.33 kg (25 lbs) in 2.26 kg (5 lbs) increments, in one hand on a wooden area equipped with a force platform. Moreover, motion data were recorded from lumbar L1 vertebrae at a frequency of 120 Hz. Three trials of data have been recorded for each subject. In order to quantify the effect of increasing loads on the GRF we define the compression area, restitution area, and coefficient of restitution (COR) for GRF curves. We observe an increase in the compression area with respect to the load and almost constant values for the COR. For motion signals analysis we employ wavelet theory. The signals obtained from the lumbar L1 sensor of the spine vertebrae show a decrease in the wavelet detail energy, for the levels 3, 4, and 5, with respect to increasing loads.

Quantification of cavitation and gapping of lumbar zygapophyseal joints during spinal manipulative therapy.

OBJECTIVES: The purpose of this study was to use previously validated methods to quantify and relate 2 phenomena associated with chiropractic spinal manipulative therapy (SMT): (1) cavitation and (2) the simultaneous gapping (separation) of the lumbar zygapophyseal (Z) joint spaces. METHODS: This was a randomized, controlled, mechanistic clinical trial with blinding. Forty healthy participants (18-30 years old) without a history of low-back pain participated. Seven accelerometers were affixed to the skin overlying the spinous processes of L1 to L5 and the S1 and S2 sacral tubercles. Two additional accelerometers were positioned 3 cm left and right lateral to the L4/L5 interspinous space. Participants were randomized into group 1, side-posture SMT (n = 30), or group 2, side-posture positioning (SPP, n = 10). Cavitations were determined by accelerometer recordings during SMT and SPP (left side = upside for both groups); gapping (gapping difference) was determined by the difference between pre- and postintervention magnetic resonance imaging scan joint space measurements. Results of mean gapping differences were compared. RESULTS: Upside SMT and SPP joints gapped more than downside joints (0.69 vs -0.17 mm, P < .0001). Spinal manipulative therapy upside joints gapped more than SPP upside joints (0.75 vs 0.52 mm, P = .03). Spinal manipulative therapy upside joints gapped more in men than in women (1.01 vs 0.49 mm, P < .002). Overall, joints that cavitated gapped more than those that did not (0.56 vs 0.22 mm, P = .01). No relationship was found between the occurrence of cavitation and gapping with upside joints alone (P = .43). CONCLUSIONS: Zygapophyseal joints receiving chiropractic SMT gapped more than those receiving SPP alone; Z joints of men gapped more than those of women, and cavitation indicated that a joint had gapped but not how much a joint had gapped.

Wear patterns of tibiofemoral articulation in osteoarthritic knees: analysis and review of literature.

INTRODUCTION: Osteoarthritis is a degenerative joint disease characterized by progressive erosion of the articular cartilage. The sites of erosion of articular cartilage have been reported, but no explanation for this particular pattern has previously been suggested. AIMS: To analyze the gross features of lesions, together with their frequency of occurrence and situation, and wear relationship with individual body profile. MATERIALS AND METHODS: Data collected from the dissection of 102 cadavers at a tertiary hospital. RESULTS: Wear patterns on the tibial surface show that the areas involved in the majority of cases include middle medial and middle lateral regions of the tibial plateau. There also seemed to be a strong correlation between age, body mass index and the wear pattern. The incidence of posteromedial erosions on the tibial plateau was mainly seen in the ACL-deficient knee. Also, incidence of lateral meniscus tears was found to be higher in the ACL-deficient knees. CONCLUSION: In osteoarthritis of the knee joint, the middle third of both the femoral and tibial articular surfaces is most commonly involved in wears, followed by anteromedial and posterolateral compartments both for tibial and femoral surfaces. The wear patterns in the ACL-deficient knee changes due to altered loading characteristics.

Distribution of cavitations as identified with accelerometry during lumbar spinal manipulation.

OBJECTIVE: This project determined the location and distribution of cavitations (producing vibrations and audible sounds) in the lumbar zygapophyseal (Z) joints that were targeted by spinal manipulative therapy (SMT). METHODS: This randomized, controlled, clinical study assessed 40 healthy subjects (20 men, 20 women) 18 to 30 years of age who were block randomized into SMT (group 1, n = 30) or side-posture positioning only (group 2; control, n = 10) groups. Nine accelerometers were placed on each patient (7 on spinous processes/sacral tubercles of L1-S2 and 2 placed 3 cm left and right lateral to the L4/L5 interspinous space). Accelerometer recordings were made during side-posture positioning (groups 1 and 2) and SMT (group 1 only). The SMT was delivered by a chiropractic physician with 19 years of practice experience and included 2 high-velocity, low-amplitude thrusts delivered in rapid succession. Comparisons using χ(2) or McNemar test were made between number of joints cavitating from group 1 vs group 2, upside (contact side for SMT) vs downside, and Z joints within the target area (L3/L4, L4L5, L5/S1) vs outside the target area (L1/L2, L2/L3, sacroiliac). RESULTS: Fifty-six cavitations were recorded from 46 joints of 40 subjects. Eight joints cavitated more than once. Group 1 joints cavitated more than group 2 joints (P < .0001), upside joints cavitated more than downside joints (P < .0001), and joints inside the target area cavitated more than those outside the target area (P < .01). CONCLUSIONS: Most cavitations (93.5%) occurred on the upside of SMT subjects in segments within the target area (71.7%). As expected, SMT subjects cavitated more frequently than did subjects with side-posture positioning only (96.7% vs 30%). Multiple cavitations from the same Z joints had not been previously reported.

Fixation techniques for non-union of the scaphoid.

PURPOSE: To compare outcomes of 3 fixation modalities for scaphoid non-union. METHODS: 27 men and 6 women aged 20 to 48 (mean, 28) years with non-union of the scaphoid involving the proximal pole (n=13), waist (n=12), and distal pole (n=8) were randomised to undergo the Herbert screw fixation (n=11), the Matti Russe bone grafting (n=9), or the Kohlman modification of vascularised muscle pedicle graft procedure (n=13). The mean duration of non-union was 10 (range, 6-30) months. RESULTS: The mean follow-up duration was 28 months. 30 of 33 achieved correction of both scapholunate and radiolunate angles. The mean range of motion increased from 112 to 155 degrees. The mean grip strength increased by 30%. Functional outcomes of the 3 groups were comparable; they were excellent in 13 patients, good in 10, fair in 6, and poor in 4. There was no hardware failure or any iatrogenic fracture during pedicle dissection. One patient had a superficial infection, which was resolved after antibiotic treatment. At the 6-month follow-up, in the respective 3 groups, 8, 6 and 11 patients achieved scaphoid union after mean intervals of 17, 16, and 15 weeks. CONCLUSION: The time to union was earliest in the Kohlman modification of vascularised muscle pedicle graft procedure, which is recommended for patients with old non-union (>1 year) or proximal pole fractures.

Evaluating the relationship among cavitation, zygapophyseal joint gapping, and spinal manipulation: an exploratory case series.

OBJECTIVE: This project determined the feasibility of conducting larger studies assessing the relationship between cavitation and zygapophyseal (Z) joint gapping following spinal manipulative therapy (SMT). METHODS: Five healthy volunteers (average age, 25.4 years) were screened and examined against inclusion and exclusion criteria. High-signal magnetic resonance imaging (MRI) markers were fixed to T12, L3, and S1 spinous processes. Scout images were taken to verify the location of the markers. Axial images of the L4/L5 and L5/S1 levels were obtained in the neutral supine position. Following the first MRI, accelerometers were placed over the same spinous processes; and recordings were made from them during side-posture positioning and SMT. The accelerometers were removed, and each subject was scanned in side-posture. The greatest central anterior to posterior Z joint spaces (gap) were measured from the first and second MRI scans. Values obtained from the first scan were subtracted from those of the second, with a positive result indicating an increase in gapping following SMT (positive gapping difference). Gapping difference was compared between the up-side (SMT) joints vs the down-side (non-SMT) joints and between up-side cavitation vs up-side noncavitation joints. RESULTS: Greater gapping was found in Z joints that received SMT (0.5 ± 0.6 mm) vs non-SMT joints (-0.2 ± 0.6 mm), and vertebral segments that cavitated gapped more than those that did not cavitate (0.8 ± 0.7 vs 0.4 ± 0.5 mm). CONCLUSIONS: A future clinical study is quite feasible. Forty subjects (30 in an SMT group and 10 in a control group) would be needed for appropriate power (0.90).

Re-radiation of acoustic waves from the A0 wave on a submerged elastic shell.

We consider evacuated thin semi-infinite shells immersed in a fluid, which may be either of cylindrical shape with a hemispherical shell endcap, or formed two-dimensionally by semi-infinite parallel plates joined together by a semi-cylinder. The connected shell portions are joined in a manner to satisfy continuity but with a discontinuous radius of curvature. Acoustic waves are considered incident along the axis of symmetry (say the z axis) onto the curved portion of the shell, where they, at the critical angle of coincidence, generate Lamb and Stoneley-type waves in the shell. Computations were carried out using a code developed by Cao et al. [Chinese J. Acoust. 14, 317 (1995)] and was used in order to computationally visualize the waves in the fluid that have been re-radiated by the shell waves a the critical angle. The frequency range was below that of the lowest Lamb wave, and only the A0 wave (and partly the S0 wave) was observed to re-radiate into the fluid under our assumptions. The results will be compared to experimental results in which the re-radiated waves are optically visualized by the Schardin-Cranz schlieren method.

Circumferential-wave phase velocities for empty, fluid-immersed spherical metal shells.

In earlier studies of acoustic scattering resonances and of the dispersive phase velocities of surface waves that generate them [see, e.g., Talmant et al., J. Acoust. Soc. Am. 86, 278-289 (1989) for spherical aluminum shells] we have demonstrated the effectiveness and accuracy of obtaining phase velocity dispersion curves from the known acoustic resonance frequencies. This possibility is offered through the condition of phase matching after each complete circumnavigation of these waves [Uberall et al., J. Acoust. Soc. Am. 61, 711-715 (1977)], which leads to a very close agreement of resonance results with those calculated from three-dimensional elasticity theory whenever the latter are available. The present investigation is based on the mentioned resonance frequency/elasticity theory connection, and we obtain comparative circumferential-wave dispersion-curve results for water-loaded, evacuated spherical metal shells of aluminum, stainless steel, and tungsten carbide. In particular, the characteristic upturn of the dispersion curves of low-order shell-borne circumferential waves (A or A0 waves) which takes place on spherical shells when the frequency tends towards very low values, is demonstrated here for all cases of the metals under consideration.

Acute reversible left ventricular dysfunction following general anesthesia.

Acute reversible left ventricular dysfunction due to myocardial stunning is a known phenomenon during acute myocardial infarction, coronary angiography, coronary angioplasty or after coronary artery bypass surgery. We report a rare case of acute reversible dysfunction of the myocardium as a complication of general anesthesia in a patient with normal coronary arteries. This is a potentially fatal complication unless recognized early and treated aggressively.

Circumferential waves on an immersed, fluid-filled elastic cylindrical shell.

The existence of various types of circumferential waves, both predominantly shell or fluid borne, and the repulsion of their dispersion curves is discussed here for an infinite, thin elastic, circular-cylindrical shell immersed in a fluid and filled with another fluid. The study is based on an analytic calculation of the partial-wave resonances in the acoustic scattering amplitude of a normally incident plane wave. A large number of cases of repulsion are found in the phase-velocity dispersion curves of the various types of circumferential waves due to the shell-fluid coupling.

Transesophageal echocardiography for the detection of left atrial thrombus.

We performed transesophageal two-dimensional echocardiography (TEE) and compared its results with those of transthoracic echocardiography (TTE) in a series of 120 patients with rheumatic mitral stenosis (MS). The patients were selected from a pool of 2000 patients of rheumatic heart disease assessed earlier by clinical examination and TTE. The selection criteria for TEE included one or more of the following: 1. Atrial fibrillation, 2. Embolic episode, 3. Before closed mitral valvotomy or balloon mitral valvuloplasty, 4. Large left atrium (LA) and 5. Evidence of clot or spontaneous echo-contrast in LA. The aim was to study the usefulness of TEE as compared to TTE in the detection of thrombus in LA. LA thrombus was imaged in 34/120 TEE studies as compared to 21/120 TTE studies. In 12/13 patients in whom TTE failed, the clot was present in the left atrial appendage (LAA). In the remaining one patient, poor echo window for TTE was responsible. In 2/6 patients with embolic episode, neither TTE nor TEE could document the presence of clot in LA. The procedure of TEE was well tolerated and there were no complications. We conclude that TEE is a safe and valuable adjunct to TTE with better diagnostic ability for the detection of LA thrombus and should be performed in all patients with MS in whom a clot in LA is suspected or needs to be excluded.

High speed rotational atherectomy in coronary artery disease.

Despite major advances in its diagnosis and management, coronary artery disease remains the major cause of death accounting for 45.3 percent of all deaths in the United States. One of the major milestones in the treatment of coronary artery disease has been the introduction of non-surgical revascularization in the form of percutaneous transluminal coronary angioplasty by Andreas Gmentzig in 1977. In the early years, PTCA could only be performed in proximal, discrete, non-calcified lesions. Over the last decade, major advances in the catheter, balloon and guide wire technology as well as increased operator experience extended the benefits of PTCA to patients with more complex lesions and multivessel coronary artery disease. Although the initial impetus for the development of newer devices has been to address the problem of restenosis, they are proving to be useful in treating lesions that are inadequately treated or subject to increased incidence of complications. The high speed rotational atherectomy is a valuable addition with its ability to treat long, calcified lesions. This report will describe the technical aspects of the Rotablator®, the procedure of high speed rotational atherectomy and its clinical applications.