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Biomedical subjects

K R Kaufman

Publications and source records attributed to K R Kaufman.

At least 19 recordsLinked to original sources
PubMed2006

Clinical evaluation of T2 values of patellar cartilage in patients with osteoarthritis.

OBJECTIVE: The transverse relaxation time constant, T2, of articular cartilage has been proposed as a biomarker for osteoarthritis (OA). Previous studies have not clearly defined the relationship between cartilage T2 values and clinical methods of grading OA or known factors associated with OA. This study compared T2 values of patellar cartilage grouped by radiographic stage of patello-femoral OA and by body mass index (BMI). METHODS: T2 values of patellar cartilage were calculated for 113 subjects using images acquired on a 1.5 T clinical scanner. Radiographs of the patello-femoral joint were graded for OA grading using the Kellgren-Lawrence scale. RESULTS: No differences of T2 values were found across the stages of OA (P = 0.25), but the factor of BMI did have a significant effect (P < 0.0001) on T2 value. CONCLUSIONS: The results indicate the T2 values are not sensitive to changes in radiographic stages of OA. In addition, differences of T2 values with BMI signify structural changes occurring within the patello-femoral joint and that BMI may be considered a factor for a potential increase of T2 values. Future studies comparing different OA grading methods with T2 mapping may highlight the sensitivity of T2 mapping in a clinical setting.

Aged↗
PubMed2006

Changes in gait associated with acute stage II posterior tibial tendon dysfunction.

The purpose of this study was to examine differences in gait mechanics between patients with acute stage II PTTD and healthy volunteers. Hindfoot and midfoot kinematics, plantar foot pressures and electromyographic (EMG) activity of the posterior tibialis, gastrocnemius, anterior tibialis and the peroneals were measured in five patients with acute stage II PTTD. Kinematics and kinetics were compared to a database of 20 healthy volunteers. EMG and plantar pressure data were obtained from five healthy volunteers. Hindfoot moments and powers were also calculated. The center of pressure excursion index (CPEI) was calculated from the plantar pressures. Significant differences were observed between the two groups, which confirmed clinical observations. Limited hindfoot eversion and increased midfoot external rotation occurred during the first and third rockers. The EMG data suggested that tendon dysfunction in the posterior tibialis is associated with compensatory activity, not only in its antagonists (the peroneals), but also in the anterior tibialis and the gastrocnemius. These data suggest that non-operative treatment of patients with PTTD should consider minimizing the activity of the posterior tibialis as well as the peroneals, the anterior tibialis and the gastrocnemius.

Adult↗
PubMed2005

Semi-automated digital image analysis of joint space width in knee radiographs.

OBJECTIVE: To design a semi-automated program to measure the minimum tibiofemoral joint space width (JSW) of knee radiographs. DESIGN: Bilateral knee radiographs were obtained twice within a 2 week period from 34 asymptomatic research participants. Radiographic images were analyzed to report both the variability of the image analysis program and the reproducibility of JSW measurements within a 2 week period. In addition, the results were compared with minimum JSW measurements read manually by an experienced musculoskeletal radiologist. RESULTS: The variability of the image analysis program was shown to be within one pixel. The results showed that reproducibility was better with the automated method. In addition, the manual method measured a greater minimum JSW than the automated method. There was no significant difference in between-day measurements. There was a significant difference reported between the automated and manual minimum JSW measurements. CONCLUSION: A novel semi-automated method for measurement of JSW has been developed.

Adult↗
PubMed2005

Modafinil in sports: ethical considerations.

Performance enhancing agents are prohibited in athletic competition so that only athletic skills can determine outcomes. Modafinil is a novel non-addicting psychostimulant approved for treatment of narcolepsy. Does its use, especially for medical indications, violate the Olympic Movement Anti-Doping Code? This is discussed with reference to a current high profile case.

Benzhydryl Compounds↗
PubMed2004

A kinematic method to calculate the workspace of the trapeziometacarpal joint.

The specific aim of this study was to develop a quantitative method and a kinematic method to evaluate the maximal workspace of the trapeziometacarpal (TM) joint. Six fresh-frozen human cadaver hands were disarticulated 4 cm proximal to the wrist joint and used in this experiment. The three-dimensional motion data of the TM joint was collected by an electromagnetic tracking device at 30 Hz. The workspace was reconstructed according to a complete set of motion data included circumduction, flexion-extension and abduction-adduction. A spherical fitting technique was used to obtain a sphere encompassing all the motion trajectories and estimating the centre of the sphere. The surface area of the maximal TM workspace, located on the one part of the sphere surface, was calculated by surface integration. The interclass correlation coefficient values for the reliability estimation of the repeated measurements of the radius and surface area of all specimens were 0.91 and 0.98 respectively. The mean coefficients of variance of the measured radius and the surface area were 2.04 per cent and 3.65 per cent respectively. The results also showed that using a spherical model to calculate the maximal workspace as an index for assessing TM joint impairment is practical.

Adolescent↗
PubMed2001

Gait characteristics of patients with knee osteoarthritis.

The knee kinematics and kinetics of 139 patients (47 males and 92 females) with Grade II knee osteoarthritis (OA) were measured during level walking, stair ascent and stair descent. There was no significant difference in knee motion between the patients and normal subjects. The patients with knee OA had a significantly reduced internal knee extensor moment compared to normal subjects. This difference reflects the patient's compensation to reduce the knee joint loading. Further, subjects with OA and a higher body mass index have a lower knee extensor moment. The female subjects had significantly greater knee flexion and a greater knee extensor moment. This gender difference may partially explain the increased prevalence of OA in females. Most tests of OA treatments are assessed by criteria that do not reflect functional activities. This study demonstrates that objective gait analysis can be used to document gait adaptations used by patients with knee OA.

Adaptation, Physiological↗
PubMed2001

Motion of the whole body's center of mass when stepping over obstacles of different heights.

Tripping over obstacles and imbalance during gait were reported as two of the most common causes of falls in the elderly. Imbalance of the whole body during obstacle crossing may cause inappropriate movement of the lower extremities and result in foot-obstacle contact. Thus, this study was performed to investigate the effect of obstacle height on the motion of the whole body's center of mass (COM) and its interaction with the center of pressure (COP) of the stance foot while negotiating obstacles. Six healthy young adults were instructed to perform unobstructed level walking and to step over obstacles of heights corresponding to 2.5, 5, 10, and 15% of the subject's height, all at a comfortable self-selected speed while walking barefoot. A 13-link biomechanical model of the human body was used to compute the kinematics of the whole body's COM. Stepping over the higher obstacles resulted in significantly greater ranges of motion of the COM in the anterior-posterior and vertical directions, a greater velocity of the COM in the vertical direction, and a greater anterior-posterior distance between the COM and COP. In contrast, the motion of the COM in the medial-lateral direction was less likely to be affected when negotiating obstacles of different heights.

Accidental Falls↗
PubMed2001

Visual fields and tiagabine: a quandary.

This case report describes the development of asymptomatic visual field defects (VFDs) in a psychiatric patient with bipolar disorder receiving adjunctive tiagabine treatment. These defects were apparently reversible upon the discontinuation of tiagabine. Controlled clinical trials are indicated to determine if this finding is indicative of a class effect for all GABAergic antiepileptic drugs (AEDs), as already noted with vigabatrin, or if this case represents an incidental finding with tiagabine (41 references).

Adult↗
PubMed2001

Patellar tracking in total knee arthroplasty: inset versus onset design.

Patellar components come in onset and inset designs. Kinematic differences between these designs were studied in a cadaver model of closed kinetic chain knee extension. Seven frozen knees were implanted with a standard posterior cruciate-retaining design. Each knee first was tested with the inset design, followed by the onset design in the Oxford Knee Rig. Three-dimensional tracking of the femur, tibia, and patella was performed using an electromagnetic system during active knee extension under load. No statistically significant differences were seen in knee kinematics between the 2 designs. The inset patella tended to shift laterally and tilt laterally more than the onset patella. This difference may be clinically significant.

Analysis of Variance↗
PubMed2000

Military training-related injuries: surveillance, research, and prevention.

BACKGROUND: Musculoskeletal physical training-related injuries are a major problem in military populations. Injuries are important in terms of loss of time from work and training and decreased military readiness. The implications of these injuries in terms of patient morbidity, attrition rates, and training costs for military personnel are staggering. This article reviews: (1) pertinent epidemiologic literature on musculoskeletal injury rates; (2) injury type and location; and (3) risk factors for military populations. Suggestions for injury surveillance and prevention are also offered. METHODS: Existing military and civilian epidemiologic studies were used to estimate and compare the size of the injury problem, identify risk factors, and test preventive measures. Most of the military research data obtained was from Marine and Army recruits, Army Infantry soldiers, and Naval Special Warfare candidates. Additional studies conducted in operational forces provided documentation of the injury problem in these populations as well. RESULTS: Injury rates during military training are high, ranging from 6 to 12 per 100 male recruits per month during basic training to as high as 30 per 100 per month for Naval Special Warfare training. Data collected show a wide variation in injury rates that are dependent largely on the following risk factors: low levels of current physical fitness, low levels of previous occupational and leisure time physical activity, previous injury history, high running mileage, high amount of weekly exercise, smoking, age, and biomechanical factors. (Data are contradictory with respect to age.) CONCLUSION: Considering the magnitude of training injuries in military populations, there is a substantial amount of work that remains to be performed, especially in the areas of surveillance, prevention, and treatment. Modifiable risk factors have been identified suggesting that overuse and other training injuries could be decreased with proper interventions. Outpatient surveillance systems are available to capture musculoskeletal injury data but need to be refined. Given the size of the problem, a systematic process of prevention should be initiated starting with routine surveillance to identify high-risk populations for the purpose of prioritizing research and prevention. Properly planned interventions should then be implemented with the expectation of dramatically reduced lost work/training time, attrition, and medical costs, while increasing military readiness.

Adult↗
PubMed2000

Academic and private practice medicine and health service delivery systems: a psychiatric commentary.

The author presents a commentary on the interactions and economic consequences of managed care, health service delivery systems, academic medicine, and psychiatry. The author recommends the creation of divisions of private practice psychiatry within academic psychiatry departments as a means to address the increasing financial pressures as well as to foster medical education, quality medical care, and clinical research.

Delivery of Health Care↗
PubMed2000

Modafinil augmentation of antidepressant treatment in depression.

BACKGROUND: Despite a relative lack of controlled data, stimulants are often used to augment antidepressant treatment in patients who have had only a partial response to first-line therapy. Modafinil is a novel psychostimulant that has shown efficacy in, and was recently marketed for, treating excessive daytime sleepiness associated with narcolepsy. The mechanism of action of modafinil is unknown, but, unlike other stimulants, the drug is highly selective for the central nervous system, has little effect on dopaminergic activity in the striatum, and appears to have a lower abuse potential. METHOD: In this retrospective case series, we describe 7 patients with DSM-IV depression (4 with major depression and 3 with bipolar depression) for whom we used modafinil to augment a partial or nonresponse to an antidepressant. The Hamilton Rating Scale for Depression was administered as part of routine clinical practice prior to treatment and at each subsequent visit. RESULTS: At doses of 100 to 200 mg/day, all 7 patients achieved full or partial remission, generally within 1 to 2 weeks. All patients had some residual tiredness or fatigue prior to starting modafinil, and this symptom was particularly responsive to augmentation. Side effects were minimal and did not lead to discontinuation of the drug in any of the patients. CONCLUSION: Modafinil appears to be a drug with promise as an augmenter of antidepressants, especially in patients with residual tiredness or fatigue. It is a particularly attractive alternative to other stimulants because of its low abuse potential and Schedule IV status.

Adult↗
PubMed1999

In-vivo function of the thumb muscles.

OBJECTIVE: The purpose of this study is to quantify the electrical activity of the thumb muscles responsible for the production of force in different directions of thumb movement. DESIGN: The isometric forces and electromyographic activity generated by seven thumb muscles were measured on five normal healthy test subjects. BACKGROUND: The thumb is very important for proper hand function. Presently available electromyographic studies of the thumb muscles provide only limited information. Most thumb muscles have more than one function. Additional studies are required to carefully examine and confirm the in-vivo relationship between the thumb muscle electromyogram and mechanical output. METHODS: The direction and magnitude of the force vector generated at the interphalangeal joint and the relative electrical activity were obtained for eight directions of thumb action. The regions of function were defined for the abductor pollicis brevis, opponens pollicis, flexor pollicis brevis, adductor pollicis, flexor pollicis longus, extensor pollicis longus, and the abductor pollicis longus. Data was collected during voluntary isometric contraction, both before and after blocking the median nerve at the wrist. RESULTS: The highest force production was obtained during flexion. The region of maximal muscle electrical activity varied for each muscle studied. The areas of maximal in-vivo muscle activity agreed with the moment arm data reported in the literature. The median nerve block eliminated the ability to produce force in abduction. CONCLUSIONS: This study has demonstrated that by combining electromyographic measurement and biomechanical analysis it is possible to confirm the relationship between in-vivo thumb muscle function and muscle mechanics in a novel manner. The findings of this study indicate the importance of the local anatomy in controlling the direction of force production.

Adult↗
PubMed1999

Double-blind study of botulinum A toxin injections into the gastrocnemius muscle in patients with cerebral palsy.

The purpose of this study was to quantify the gait of subjects receiving two injections of either botulinum A toxin or saline vehicle into the gastrocnemius muscle(s). The study group consisted of cerebral palsy patients who walked with an equinus gait pattern. This study was a randomized, double-blinded, parallel clinical trial of 20 subjects. All were studied by gait analysis before and after the injections. There were no adverse effects. Peak ankle dorsiflexion in stance and swing significantly improved in subjects who received the drug and not in controls. Results of this double blind study give support to the short term efficacy of botulinum toxin A to improve gait in selected patients with cerebral palsy.

Ankle Joint↗
PubMed1999

Carbamazepine, hepatotoxicity, organic solvents, and paints.

Hepatotoxicity secondary to carbamazepine is a serious condition which can be fatal. However, other concomitant medications or environmental factors may be the offending agents. In this case report, hepatotoxicity secondary to organic solvents and paints is described.

Alcohol Drinking↗