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Biomedical subjects

J R Andrews

Publications and source records attributed to J R Andrews.

At least 37 records · Page 2Linked to original sources
PubMed1998

Biomechanics of windmill softball pitching with implications about injury mechanisms at the shoulder and elbow.

Underhand pitching has received minimal attention in the sports medicine literature. This may be due to the perception that, compared with overhead pitching, the underhand motion creates less stress on the arm, which results in fewer injuries. The purpose of this study was to calculate kinematic and kinetic parameters for the pitching motion used in fast pitch softball. Eight female fast pitch softball pitchers were recorded with a four-camera system (200 Hz). The results indicated that high forces and torques were experienced at the shoulder and elbow during the delivery phase. Peak compressive forces at the elbow and shoulder equal to 70-98% of body weight were produced. Shoulder extension and abduction torques equal to 9-10% of body weight x height were calculated. Elbow flexion torque was exerted to control elbow extension and initiate elbow flexion. The demand on the biceps labrum complex to simultaneously resist glenohumeral distraction and produce elbow flexion makes this structure susceptible to overuse injury.

Adult↗
PubMed1997

Current concepts: the stabilizing structures of the glenohumeral joint.

Significant contemporary advances have permitted a more comprehensive understanding and development of some interesting concepts about the glenohumeral joint. The purpose of this review paper was to discuss current concepts related to the anatomic stabilizing structures of the shoulder joint complex and their clinical relevance to shoulder instability. The clinical syndrome of shoulder instability represents a wide spectrum of symptoms and signs which may produce various levels of dysfunction, from subtle subluxations to gross joint instability. The glenohumeral joint attains functional stability through a delicate and intricate interaction between the passive and active stabilizing structures. The passive constraints include the bony geometry, glenoid labrum, and the glenohumeral joint capsuloligamentous structures. Conversely, the active constraints, also referred to as the active mechanisms, include the shoulder complex musculature, the proprioceptive system, and the musculoligamentous relationship. The interaction of the active and passive mechanisms which provide passive and active glenohumeral joint stability will be thoroughly discussed in this paper.

Biomechanical Phenomena↗
PubMed1997

The physical examination of the glenohumeral joint: emphasis on the stabilizing structures.

Thorough descriptions of specific physical examination tests used to determine glenohumeral instability are lacking in the scientific literature. The purpose of this paper was to discuss the importance of the subjective history and illustrate the physical examination of the glenohumeral joint. Additionally, the authors will illustrate specific stability assessment for the glenohumeral joint based on current basic science and clinical research. The physical examination of a patient whose history suggests subtle glenohumeral joint instability may be extremely difficult for the clinician due to the normal amount of capsular laxity commonly present in most individuals. An essential component of the physical examination is a through and meticulous subjective history which includes the mechanisms of injury and/or dysfunction, chief complaint, level of disability, and aggravating movements. The physical examination must include an assessment of motion, static stability testing, muscle testing, and a neurologic assessment. A comprehensive understanding of various stability testing maneuvers is important for the clinician to appreciate. The evaluation techniques discussed in this paper should assist the clinician in determining the passive stability of the glenohumeral joint.

Humans↗
PubMed1996

Theory and practice in speech-language pathology: a review of systemic principles.

Linear, cause-effect reasoning has dominated the training and clinical practice of speech-language pathology for many years. Recently, however, the roles of many speech-language clinicians and the contexts in which they provide their clinical services have been changing, and traditional ways of viewing clinical work no longer seem to apply. This article applies principles of systems theory to such changes and advocates an integration of these principles with those of traditional, linear views to achieve a better understanding of this evolution in the clinical practice of speech-language pathology.

Child, Preschool↗
PubMed1996

Biomechanics of overhand throwing with implications for injuries.

Proper throwing mechanics may enable an athlete to achieve maximum performance with minimum chance of injury. While quantifiable differences do exist in proper mechanics for various sports, certain similarities are found in all overhand throws. One essential property is the utilisation of a kinetic chain to generate and transfer energy from the larger body parts to the smaller, more injury-prone upper extremity. This kinetic chain in throwing includes the following sequence of motions: stride, pelvis rotation, upper torso rotation, elbow extension, shoulder internal rotation and wrist flexion. As each joint rotates forward, the subsequent joint completes its rotation back into a cocked position, allowing the connecting segments and musculature to be stretched and eccentrically loaded. Most notable is the external rotation of the shoulder, which reaches a maximum value of approximately 180 degrees. This biomechanical measurement is a combination of true glenohumeral rotation, trunk hyperextension and scapulothoracic motion. Near the time of maximum shoulder external rotation (ERmax), shoulder and elbow musculature eccentrically contract to produce shoulder internal rotation torque and elbow varus torque. Both the shoulder and the elbow are susceptible to injury at this position. At ball release, significant energy and momentum have been transferred to the ball and throwing arm. After ball release, a kinetic chain is used to decelerate the rapidly moving arm with the entire body. Shoulder and elbow muscles produce large compressive forces to resist joint distraction. Both joints are susceptible to injury during arm deceleration.

Arm↗
PubMed1996

Genetic analysis of the lozenge gene complex in Drosophila melanogaster: adult visual system phenotypes.

Mutations at the lozenge (lz) locus are pleiotropic, primarily affecting the sense organs for sight, smell and taste. To better understand the role that lz plays in the visual system, we investigated its complex genetics and the effect mutations have on the structure of the compound eye. Complementation analysis within the lz locus reveals two functional units necessary for a normal eye, cistrons A and B. Previous recombination studies identified four subloci spanning 0.14 m.u. Cistron A mutations map to the distal-most spectacle sub-locus, which has been identified as an insertion point for P-elements. Southern blotting and chromosomal in situ hybridization show that P-allele lzmu2 contains a single P-element; a cosmid clone derived from lzmu2 confirms that the P-element is defective. Mutants of both cistrons perturb lens structure and eye pigmentation. However, the extent of the defects differs between the most severe mutations of the two cistrons. Within the eye, failure to form the fenestrated membrane permits photoreceptor neurons to "fall" into the brain disrupting neural structure. Our analysis shows that lz exerts control over the identity of cone cells, pigment cells and photoreceptor neurons.

Alleles↗
PubMed1995

Ulnar collateral ligament injury in the throwing athlete: evaluation with saline-enhanced MR arthrography.

PURPOSE: To determine whether magnetic resonance (MR) arthrography of the elbow can demonstrate precisely an ulnar collateral ligament (UCL) abnormality in the throwing athlete. MATERIALS AND METHODS: Forty college-level and professional throwing athletes (age range, 18-40 years) underwent saline-enhanced MR arthrography of their injured elbows. MR findings were compared with the surgical findings. RESULTS: Saline-enhanced MR arthrography was positive in 24 of 26 individuals with UCL tear confirmed at the time of surgery. Eighteen (95%) of 19 complete UCL tears and six (86%) of seven partial UCL tears were diagnosed with MR arthrography. Two false-negative findings and no false-positive findings were obtained. CONCLUSION: Saline-enhanced MR arthrography of the elbow is a new application of a previously described technique used in the shoulder. It is useful for demonstration of subtle and gross UCL abnormalities in the throwing athlete.

Adolescent↗
PubMed1995

Identification of Trichinella pseudospiralis from a human case using random amplified polymorphic DNA.

A human case of infection by Trichinella pseudospiralis has recently been described. Some morphologic anomalies of the muscle larvae, however, raise the possibility of an incorrect taxonomic attribution. A molecular taxonomic approach has therefore been applied for the identification of the parasite. Random amplified polymorphic DNAs were obtained from a single larva extracted from a muscle biopsy of the suspected case of T. pseudospiralis infection, and compared with those derived from 27 reference strains of Trichinella spp. Nearly identical amplification patterns were obtained from the suspected larva and from reference strains of T. pseudospiralis, thus supporting the original morphology-based identification. An enzyme-linked immunosorbent assay and Western blots carried out on pretreatment and post-treatment sera provided further confirmation.

Adult↗
PubMed1995

Arthroscopic anatomy of the elbow.

Elbow arthroscopy is becoming a mainstream orthopedic procedure. Through multiple portals, a thorough evaluation of the entire elbow joint is possible. However, an understanding of normal arthroscopic anatomy is essential for orientation and alienation of pathologic processes.

Arthroscopy↗
PubMed1994

Stress radiography of the medial elbow ligaments.

PURPOSE: To study the usefulness of stress radiography for evaluation of injury to the medial collateral ligament (MCL). MATERIALS AND METHODS: Forty-two injured athletes and four healthy athletes without symptoms underwent examination performed with a stress device. The increase in joint space width between the medial epicondyle and coronoid process, measured on anteroposterior radiographs obtained after 0 and 15 daN force was applied to the lateral elbow joint, was used to assess the extent of ligament tear. The validity of this technique was tested with study of selectively severed cadaveric MCLs. RESULTS: All complete and large partial tears were correctly diagnosed with stress radiography when the increase in joint space width was larger by 0.5 mm in the affected elbow compared with the opposite normal elbow. In subjects with values less than 0.5 mm, the MCLs were normal or showed a small tear that could be managed conservatively. CONCLUSION: Stress radiography of the MCL enables accurate diagnosis of large and complete tears and distinction between such tears and small partial tears and normal ligaments.

Arthrography↗
PubMed1994

The relationship between subjective knee scores, isokinetic testing, and functional testing in the ACL-reconstructed knee.

It is important to examine the functional relationships between commonly performed clinical tests and to resolve inconsistencies in previous investigative results. The purpose of this study was to determine if a correlation exists between three commonly performed clinical tests: isokinetic isolated knee concentric muscular testing, the single-leg hop test, and the subjective knee score in anterior cruciate ligament reconstructed knees. To determine if a relationship exists would be beneficial to clinicians in determining patient progression, treatment modification, and return-to-sport objective parameters. Several investigators have analyzed two of these parameters, but no one has investigated three parameters to date. Additionally, this study explored the concept of limb acceleration and deceleration during high-speed isokinetics and its relationship to function. Fifty patients were randomly selected (29 males) with a mean age of 23.7 years (range 15-52). The subjects completed a subjective knee score questionnaire that rated symptoms (pain, swelling, giving way) and specific sport function and completed an overall knee score assessment. The patients were then evaluated performing three one-legged functional tests: 1) hop for distance, 2) timed hop, and 3) cross-over triple hop. Isokinetic testing was performed on a Biodex dynamometer at 180, 300, and 450 degrees/sec for knee extension/flexion. The patients' mean value of the self-assessed knee rating was 86 points. Sixty-four percent of the patients exhibited normal limb symmetry (within 85%) on all three single-leg hop tests. Sixteen percent exhibited quadriceps strength at least 90% of the contralateral limb isokinetically. A positive correlation was noted between isokinetic knee extension peak torque (180, 300 degrees/sec) and subjective knee scores, and the three hop tests (p < 0.001). A statistical trend was noted between knee extension acceleration and deceleration range at 180 and 300 degrees/sec for the timed hop test and triple cross-over hop (r = 0.48, r = 0.49, r = 0.51, r = 0.49). No positive correlations were found for isokinetic test results for the knee flexors.

Adolescent↗
PubMed1994

Isolated posterior cruciate ligament injuries. History, mechanism of injury, physical findings, and ancillary tests.

An accurate diagnosis of an isolated PCL injury may be difficult, especially in the acute setting. A detailed history emphasizing the mechanism of injury is crucial as is a careful, complete examination of the knee. Plain and stress radiographs may be helpful in establishing the diagnosis; however, MR imaging is currently the most sensitive ancillary study available to evaluate the integrity of the posterior cruciate ligament. Failure to recognize and treat appropriately an isolated PCL disruption may result in the development of symptomatic irreversible articular surface injury.

Athletic Injuries↗
PubMed1993

Role of the seton in the management of anorectal fistulas.

PURPOSE: To identify the incidence of major fecal incontinence and recurrence after staged fistulotomy using a seton. METHODS: A five-year retrospective chart review of 116 patients (70 males and 46 females) ranging in age from 18 to 81 years (mean, 42 years), in whom setons were placed as part of a surgical procedure for anorectal fistulas, was carried out. Follow-up ranged from 2 to 61 months (mean, 23 months). RESULTS: Setons were employed to identify and promote fibrosis around a complex anorectal fistula as part of a staged fistulotomy in 65 patients (56 percent). Other indications for seton placement included 24 women with anteriorly situated high transsphincteric fistulas (21 percent) and three patients with massive anorectal sepsis (floating, freestanding anus) (2.5 percent). In addition, setons were used to preclude premature skin closure and promote controlled long-term fistula drainage in 21 patients with severe anorectal Crohn's disease (18 percent) and in three patients with AIDS (2.5 percent). Major fecal incontinence (requiring the use of a perineal pad) occurred in five patients (5 percent), and recurrent fistulas were noted in three (3 percent). CONCLUSIONS: Staged fistulotomy using a seton is a safe and effective method of treating high or complicated anorectal fistulas.

Adolescent↗
PubMed1993

The effects of pad placement and angular velocity on tibial displacement during isokinetic exercise.

The purpose of this study was to compare the effects of proximal single resistance pad placement (PSPP) and distal single pad placement (DSPP) on tibial displacement during isokinetic exercise on anterior cruciate ligament (ACL)-deficient knees. This study is important to the clinician because it documents tibial displacement during open chain isokinetic knee extension exercise at various isokinetic speeds. In addition, this study documents the range of motion where the greatest amount of anterior tibial displacement occurs. The anterior displacement of the tibia was recorded by a computerized knee laxity testing device during isokinetic exercise. Data were collected from 12 ACL-deficient knees. Each subject was tested on an OSI Knee Signature System for quantifiable tibial displacement during a Lachman's test, anterior drawer test, and active vs. passive knee extension. Following this, each subject was tested on a Biodex isokinetic dynamometer at isokinetic velocities of 60, 180, and 300 degrees/sec with the computerized knee laxity testing device in place. Pad placement consisted of distal single pad placement, which is 1 inch proximal to the medial malleolus, and proximal single pad placement, which is 3 inches proximal to the DSPP location. The testing procedure was standardized, and peak torque was monitored to ensure consistent maximal effort throughout the study. The results indicated that PSPP resulted in less anterior tibial displacement at all three test speeds. The peak anterior tibial displacement occurred in a range from 30 to 15 degrees of knee flexion at both pad placements and all three test speeds.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗