Biomedical subjects

G R Williams

Publications and source records attributed to G R Williams.

At least 37 records · Page 2Linked to original sources

PubMed2001

The floating shoulder: a biomechanical basis for classification and management.

BACKGROUND: The floating shoulder (ipsilateral fractures of the clavicular shaft and the scapular neck) is thought to be an unstable injury pattern requiring operative stabilization in most instances. This recommendation has been made with little biomechanical data to support it. The purpose of this study was to determine the osseous and ligamentous contributions to the stability of experimentally created scapular neck fractures in a cadaver model. METHODS: Standardized scapular neck fractures were made in twelve fresh-frozen human cadaveric shoulders. Each specimen was mounted in a specially designed testing apparatus and secured to a standard materials testing device. In group 1 (six shoulders), resistance to medial displacement was determined following sequential creation of an ipsilateral clavicular fracture, coracoacromial ligament disruption, and acromioclavicular capsular disruption. In group 2 (six shoulders), resistance to medial displacement was determined following sequential sectioning of the coracoacromial and coracoclavicular ligaments. RESULTS: The average measured force for all specimens (groups 1 and 2) after scapular neck fracture was 183 +/- 3.3 N (range, 166 to 203 N). The addition of a clavicular fracture (group 1) resulted in an average measured force of 128 +/- 10.5 N (range, 83 to 153 N), which corresponds to only a 30% loss of stability. Subsequent sectioning of the coracoacromial and acromioclavicular capsular ligaments yielded an average force of 126 +/- 9.1 N (range, 114 to 144 N), a 31% loss of stability, and 0 N, a complete loss of stability, respectively. Sectioning of the coracoacromial and coracoclavicular ligaments after scapular neck fracture (group 2) resulted in an average force of 103 +/- 8.4 N (range, 89 to 118 N), a 44% loss of stability, and 0 N, a complete loss of stability, respectively. CONCLUSIONS: Ipsilateral fractures of the scapular neck and the clavicular shaft do not produce a floating shoulder without additional disruption of the coracoacromial and acromioclavicular capsular ligaments. These and other unstable combined injury patterns are likely to be accompanied by substantial medial displacement of the glenoid fragment.

Aged↗

PubMed2001

Arthroscopic capsular release for the treatment of refractory postoperative or post-fracture shoulder stiffness.

BACKGROUND: Arthroscopic capsular release is used to treat idiopathic adhesive capsulitis (frozen shoulder) that is refractory to nonoperative treatment or manipulation under anesthesia. The role of arthroscopic capsular release in the treatment of frozen shoulder after shoulder surgery or fracture is less clearly understood. The purposes of this study were to define the outcome of arthroscopic capsular release in the management of frozen shoulder after surgery or fracture and to compare these results with those of arthroscopic capsular release in the treatment of idiopathic frozen shoulder. METHODS: We evaluated the results of arthroscopic capsular release in three different groups of patients with shoulder contracture refractory to nonoperative management and manipulation under anesthesia. The three groups consisted of patients who had an idiopathic frozen shoulder, shoulder stiffness after surgery, or shoulder stiffness after fracture. We evaluated pain, function, patient satisfaction, and range of motion in all three groups before and after the study treatment. RESULTS: At a mean of twenty months (range, twelve to forty-six months) after the operation, fifty patients were available for assessment of function and range of motion of the involved shoulder. At the time of follow-up, each group had a significant improvement in the scores for pain, patient satisfaction, and functional activity as well as in the overall outcome score (p < 0.01). Comparison of the scores among the different groups revealed that all had a similar degree of improvement in range of motion of the involved shoulder, but patients with postoperative frozen shoulder had significantly (p < 0.05) lower scores for pain (p < 0.03), patient satisfaction (p < 0.004), and functional activity (p < 0.002) than did those with idiopathic or post-fracture frozen shoulder. CONCLUSIONS: Arthroscopic capsular release was as effective for improving range of motion in patients with postoperative contracture of the shoulder as it was in patients with idiopathic and post-fracture contracture. However, there was less improvement in the subjective scores for pain, function, and patient satisfaction in the postoperative group.

Analysis of Variance↗

PubMed2001

Suprascapular neuropathy. Variability in the diagnosis, treatment, and outcome.

The functional outcome of operative and nonoperative treatment of suprascapular neuropathy was compared to determine the preferred method of treatment for each etiology of nerve injury. The predictive value of preoperative electromyography also was studied. Fifty-three patients were evaluated at least 1 year (average, 28 months) from the time of operative (n = 36) or nonoperative (n = 17) treatment. A modified American Shoulder and Elbow Surgeons self-assessment score was obtained at presentation and at final followup. Electromyography data were obtained at initial presentation. Minimal electromyographic changes associated with denervation were associated with a limited response to treatment, especially in patients with nerve compression secondary to spinoglenoid notch cysts. Pretreatment electromyographic findings, therefore, were predictive of treatment response. Overall, operative and nonoperative treatment of these suprascapular nerve injuries resulted in significant functional improvement, but the results varied depending on the etiology of the injury. Spinoglenoid notch cysts responded significantly better to operative treatment, with the results for open surgery being the same as the results for arthroscopic decompression. In addition, compressive lesions attributable to suprascapular notch entrapment had the best improvement with surgical decompression. Traumatic lesions, including traction and direct closed injuries, had an equal response to operative and nonoperative treatment. Overuse injuries did not improve with operative treatment. Viral neuritis improved with nonoperative treatment and never was treated with surgery. Overall, traumatic injuries resulted in significantly worse final outcomes than any other etiologic processes. In the nonoperative group, neuropathy secondary to spinoglenoid cysts resulted in significantly worse function. The outcome of treatment is dependent on the severity and etiology of the nerve injury, and the method of treatment.

Adolescent↗

PubMed2001

Factors affecting the outcome of total shoulder arthroplasty.

Total shoulder arthroplasty (TSA) has become the treatment of choice for most glenohumeral arthritides. Results are variable and depend on many factors, including normal and prosthetic anatomy and biomechanics, surgical technique, rotator-cuff integrity, bone deficiency, and postoperative rehabilitation. In this article, we discuss these factors and their influence on achieving successful TSAs.

Arthroplasty, Replacement↗

PubMed2001

Effect of moderate weight loss on health-related quality of life: an analysis of combined data from 4 randomized trials of sibutramine vs placebo.

OBJECTIVES: To determine whether (1) patients who experience greater weight loss also experience correspondingly greater improvements in health-related quality of life (HRQOL); (2) the improvement in HRQOL is noticeable for patients achieving moderate (5%-10%) weight reduction; and (3) the relationship between weight reduction and HRQOL is similar for patients receiving sibutramine hydrochloride vs placebo. STUDY DESIGN: We combined data from 4 double-blind, randomized, controlled trials of administration of sibutramine (20 mg/d) vs placebo. PATIENTS AND METHODS: Patients (n = 555) were mildly to moderately obese and had type 2 diabetes mellitus, dyslipidemia, or hypertension that was well controlled with an angiotensin-converting enzyme inhibitor or calcium channel blocker. The HRQOL was operationalized using the Impact of Weight on Quality of Life (IWQOL) and the Medical Outcomes Study 36-Question Short-Form (SF-36) instruments. The main statistical technique was a patient-level analysis of variance predicting change in HRQOL from study, treatment, and weight change. RESULTS: Moderate weight loss was associated with a statistically significant improvement in HRQOL for approximately half of the subscales evaluated (P < .05). The greatest sensitivity to change was shown by the SF-36 general health perception and change in health since last year subscales and the IWQOL overall health, mobility, and total subscales. Greater weight loss was associated with the most improvement in HRQOL. Weight losses of 5.01% to 10.00% were associated with 2-unit changes in the SF-36 general health perception subscale and 10-unit changes in the IWQOL total subscale. Results were similar across study and treatment. CONCLUSIONS: Moderate weight loss is associated with noticeably improved HRQOL. Improvements in HRQOL are achievable by patients receiving sibutramine.

Adult↗

PubMed2001

Non-surgical therapy of primary hyperparathyroidism.

BACKGROUND: Primary hyperparathyroidism is a commonly encountered illness that can usually be treated successfully with surgery. However, non-surgical ablation by either infusion of contrast media via angiography or percutaneous injection of ethanol has been reported from a few medical centers. METHODS: All patients undergoing non-surgical treatment of primary hyperthyroidism at the University of Oklahoma Health Sciences Center were identified and their records reviewed. RESULTS: We have used non-surgical techniques to treat three patients with primary hyperparathyroidism. The patients were considered poor surgical candidates or had persistent hypercalcemia after neck exploration. Hypercalcemia was improved or cured in each of the patients without recurrence. CONCLUSIONS: Our application of these techniques indicates that centers without extensive experience can successfully employ angiographic or ethanol ablation of parathyroid adenomas.

Adenoma↗

PubMed2000

Pituitary-thyroid feedback hypersensitivity as a novel cause of hypothyroidism in children.

Recognition and treatment of childhood hypothyroidism is essential to prevent serious developmental abnormalities, and neonatal screening based on detection of raised thyrotropin concentrations is routine. We investigated an adolescent who had developmental retardation because of an undiagnosed and novel cause of childhood hypothyroidism associated with normal circulating thyrotropin concentrations. Dynamic testing showed a hypersensitive pituitary-thyroid feedback axis with no evidence of other pituitary or hypothalamic disease, and sequence analysis of four candidate causative genes was negative. A high index of suspicion is required to diagnose and treat this disorder to prevent the consequences of long-term hypothyroidism on development.

Adolescent↗

PubMed2000

A modified nasopharyngeal tube to relieve high upper airway obstruction.

Infants with high upper airway obstruction (UAO) are managed with a variety of techniques to relieve their UAO. Among these techniques, the least invasive and safest is the nasopharyngeal tube (NPT). However, the traditional NPT is not always satisfactory, and tracheostomies need to be done. We recently described a modified NPT technique that, in contrast to the traditional tube, does not add airway dead space and resistance, is easy to use, is well-tolerated, has proven highly successful, and allows the simultaneous use of oxygen nasal prongs. This modified NPT has many advantages over the traditional NPT as a temporary management of high UAO that resolves with growth of the infant. This report highlights the respiratory care of 10 infants with high UAO (Pierre Robin syndrome, Down syndrome, Goldenhar syndrome, isolated microngathia, and idiopathic hypotonia) who were managed with a modified NPT. The modified NPT described potentially reduces the need for surgical intervention to relieve high UAO in infants.

Airway Obstruction↗

PubMed2000

Two-part and three-part fractures: open reduction and internal fixation versus closed reduction and percutaneous pinning.

Surgical management of two-part and three-part proximal humerus fractures is difficult and requires familiarity with more than one method of fixation. Poor bone quality, comminution, and the deforming forces of the rotator cuff on the tuberosities influence the choice of operative approach and fixation techniques. Closed reductions and percutaneous pinning offer the potential advantage of minimal soft-tissue dissection; however, good bone quality and minimal comminution are prerequisites. Selected two-part surgical neck fractures and valgus-impacted fractures lend themselves well to this technique. Open reduction and internal fixation is indicated in two-part surgical neck fractures with poor bone quality or extensive comminution, two-part greater tuberosity or lesser tuberosity fractures, and most three-part fractures. The choice of surgical approach is dictated by the fracture pattern and includes an extended deltopectoral approach and a superior deltoid-splitting approach. Fixation techniques are myriad and are dependent on the fracture pattern. Potential fixation methods include intramedullary rods, interfragmentary sutures or wires, and extramedullary plates and screws or blade plates. Successful results are predicated on obtaining adequate enough fixation to allow early passive motion. Results also are influenced by the quality of the reduction and patient compliance.

Bone Nails↗

PubMed2000

Conservative management of sternoclavicular injuries.

Injuries to the sternoclavicular joint are rare because of its strong ligamentous support. Because of the strong forces involved and the proximity of the joint to the great vessels and other mediastinal structures, however, sternoclavicular injuries can be very serious and potentially life threatening. Sternoclavicular injuries include traumatic sprains and dislocations, atraumatic spontaneous dislocations, and epiphyseal fractures in patients under 25 years of age. Diagnosis is made by history, physical examination, and radiographic studies such as the CT scan. Conservative management consists of benign neglect and closed or percutaneous reduction and immobilization. If the injury is treated acutely, conservative management often produces good long-term results.

Humans↗

PubMed2000

Severe obstructive sleep apnoea secondary to pressure garments used in the treatment of hypertrophic burn scars.

Obstructive sleep apnoea (OSA) secondary to pressure garments used to treat hypertrophic scarring of burns has never been reported. The present study describes two children who presented with OSA following introduction of such garments for management of hypertrophic scars following severe facial and upper body burns. Complex sleep polysomnography confirmed severe OSA with desaturations sufficient to result in physiological dysfunction that significantly improved on removal of the garments. As there is little evidence to suggest that the use of such garments alters the end result, the potentially serious side effect of obstructive sleep apnoea should be considered before their use is advised.

Adolescent↗

PubMed2000

Cloning and characterization of two novel thyroid hormone receptor beta isoforms.

Thyroid hormone (T(3)) activates nuclear receptor transcription factors, encoded by the TRalpha (NR1A1) and TRbeta (NR1A2) genes, to regulate target gene expression. Several TR isoforms exist, and studies of null mice have identified some unique functions for individual TR variants, although considerable redundancy occurs, raising questions about the specificity of T(3) action. Thus, it is not known how diverse T(3) actions are regulated in target tissues that express multiple receptor variants. I have identified two novel TRbeta isoforms that are expressed widely and result from alternative mRNA splicing. TRbeta3 is a 44.6-kDa protein that contains an unique 23-amino-acid N terminus and acts as a functional receptor. TRDeltabeta3 is a 32.8-kDa protein that lacks a DNA binding domain but retains ligand binding activity and is a potent dominant-negative antagonist. The relative concentrations of beta3 and Deltabeta3 mRNAs vary between tissues and with changes in thyroid status, indicating that alternative splicing is tissue specific and T(3) regulated. These data provide novel insights into the mechanisms of T(3) action and define a new level of specificity that may regulate thyroid status in tissue.

5' Untranslated Regions↗

PubMed2000

Development of an ischemic stroke survival score.

BACKGROUND AND PURPOSE: There has been substantial interest in identifying predictors of survival for stroke patients. Current instruments used for measuring stroke severity are confined to either neurological, functional, or disability measures. The purpose of this study was to develop a stroke survival score that combines instruments from different domains to better predict long-term survival. METHODS: We took advantage of a particularly broad array of clinical and physiological variables collected during the Stroke Treatment with Ancrod Trial. Four hundred fifty-three patients completed a battery of instruments at day 7 after stroke and then were followed for 1 year. RESULTS: Of the 453 patients, 53% were male, 77% were aged 65 years or older, and 89% were white. One hundred nine patients (24%) died during the study period. Age was a highly significant predictor of mortality (P<0.001), but there were no statistically significant differences in 12-month survival with respect to sex, race, or educational level. The best model for predicting survival was the Ischemic Stroke Survival Score. This model included the Scandinavian Stroke Scale, Rapid Disability Rating Scale, age, and prior stroke. This model had substantially greater predictive power (R(2)=0.30, c statistic=0.86) than the Scandinavian Stroke Scale alone (R(2)=0.20, c statistic=0.78). CONCLUSIONS: This study demonstrates that combining day 7 poststroke information from multiple domains substantially improves the ability to predict 12-month survival of ischemic stroke patients compared with data from a single domain. The high mortality rate emphasizes the importance of preventive measures for a disease that has identifiable and modifiable risk factors.

Age Distribution↗

PubMed2000

Thyroid hormone acts directly on growth plate chondrocytes to promote hypertrophic differentiation and inhibit clonal expansion and cell proliferation.

T3 is an important regulator of endochondral bone formation in epiphyseal growth plates. Growth arrest in juvenile hypothyroidism results from disorganization of growth plate chondrocytes and their failure to undergo hypertrophic differentiation, but it is unclear how T3 acts directly on chondrocytes or whether its actions involve other pathways. To address this issue, we investigated whether thyroid hormone receptors (TR) were localized to discrete regions of the unfused epiphysis by immunohistochemistry performed in tibial growth plates from 21-day-old rats and examined the effects of T3 on growth plate chondrocytes in agarose suspension cultures in vitro. TRalpha1, -alpha2, and -beta1 were expressed in reserve and proliferating zone chondrocytes, but not in hypertrophic cells, suggesting that progenitor cells and immature chondrocytes are the major T3 target cells in the growth plate. Chondrocytes in suspension culture expressed TRalpha1, -alpha2, and -beta1 messenger RNAs and matured by an ordered process of clonal expansion, colony formation, and terminal hypertrophic differentiation. Clonal expansion and proliferation of chondrocytes were inhibited by T3, which also induced alkaline phosphatase activity, expression of collagen X messenger RNA, and secretion of an alcian blue-positive matrix as early as 7 days after hormone stimulation. Thus, T3 inhibited chondrocyte clonal expansion and cell proliferation while simultaneously promoting hypertrophic chondrocyte differentiation. These data indicate that thyroid hormones concurrently and reciprocally regulate chondrocyte cell growth and differentiation in the endochondral growth plate.

Animals↗

PubMed2000

Thyroid hormones regulate hypertrophic chondrocyte differentiation and expression of parathyroid hormone-related peptide and its receptor during endochondral bone formation.

Hypothyroidism in children causes developmental abnormalities in bone and growth arrest, while thyrotoxicosis accelerates growth rate and advances bone age. To determine the effects of thyroid hormones on endochondral bone formation, we examined epiphyseal growth plates in control, hypothyroid, thyrotoxic, and hypothyroid-thyroxine (hypo-T4)-treated rats. Hypothyroid growth plates were grossly disorganized, contained an abnormal matrix rich in heparan sulfate, and hypertrophic chondrocyte differentiation failed to progress. These effects correlated with the absence of collagen X expression and increased parathyroid hormone-related protein (PTHrP) messenger RNA (mRNA) expression. In thyrotoxic growth plates, histology essentially was normal but PTHrP receptor (PTHrP-R) mRNA was undetectable. PTHrP is a potent inhibitor of hypertrophic chondrocyte differentiation that acts in a negative feedback loop with the secreted factor Indian hedgehog (Ihh) to regulate endochondral bone formation. Thyroid hormone receptor alpha1(TRalpha1), TRalpha2, and TRbeta1 proteins were localized to reserve zone progenitor cells and proliferating chondrocytes in euthyroid rat cartilage; regions in which PTHrP and PTHrP-R expression were affected by thyroid status. Thus, dysregulated Ihh/PTHrP feedback loop activity may be a key mechanism that underlies growth disorders in childhood thyroid disease.

Animals↗

PubMed2000

Rotation of the clavicular portion of the pectoralis major for soft-tissue coverage of the clavicle. An anatomical study and case report.

BACKGROUND: The purposes of this study were to describe the anatomical features of a rotational flap consisting of the clavicular portion of the pectoralis major and to report the surgical technique and the outcome of use of this flap in a patient with poor soft-tissue coverage following multiple operations for a clavicular fracture complicated by nonunion and infection. METHODS: Ten shoulders from five cadavera were dissected to isolate the clavicular portion of the pectoralis major. The vascular pedicle, thoracoacromial artery, and axillary artery were identified, and the length of the vascular pedicle from the axillary artery to the muscle was measured. The angle of rotation of the flap about its intact clavicular origin was measured before and after division of the acromial branch of the thoracoacromial artery. The clavicular origin was then incised, and the overall length, width, and thickness of the muscle as well as the distance from each end of the muscle to the vascular pedicle were measured. RESULTS: The average length of the vascular pedicle from the axillary artery to the pectoralis muscle belly was 5.3 centimeters (range, 3.7 to 6.5 centimeters). The average maximum angle of rotation with the clavicular origin intact was 60 degrees (range, 55 to 67 degrees) before division of the acromial branch and 73 degrees (range, 65 to 82 degrees) after division. The average total length of the clavicular head was 20.2 centimeters (range, 18.0 to 23.0 centimeters). The average width of the clavicular head was 2.9 centimeters (range, 2.0 to 4.0 centimeters), and the average thickness was 0.5 centimeter (range, 0.2 to 0.7 centimeter). The vascular pedicle entered the muscle an average of 8.7 centimeters (range, 5.2 to 10.7 centimeters) lateral to the most medial extent of the muscle and an average of 11.5 centimeters (range, 9.5 to 14.0 centimeters) medial to the most lateral extent of the muscle. The rotational flap was successfully used clinically to provide soft-tissue coverage after bone-grafting and internal fixation of a clavicular nonunion that had been complicated by infection. CONCLUSIONS: The clavicular head of the pectoralis major may be used as a local rotational flap to cover soft-tissue deficiencies over the clavicle. It can be harvested with relative ease without damaging the sternocostal head.

Aged↗

PubMed2000

Management of rotator cuff and impingement injuries in the athlete.

OBJECTIVE: To review current concepts of the pathophysiology, diagnosis, and treatment of rotator cuff and impingement injuries in the athlete. DATA SOURCES: The information we present was compiled from a review of classic and recently published material regarding rotator cuff and impingement injuries. These materials were identified through a search of a personal literature database compiled by the authors, as well as by selective searching of the MEDLINE. In addition, much of the information presented represents observations and opinions of the authors developed over 8 to 10 years of treating shoulder injuries in athletes. DATA SYNTHESIS: Biomechanics of the normal shoulder and pathophysiology of rotator cuff injuries in the athletic population are discussed, followed by a summary of the important diagnostic features of rotator cuff and impingement injuries. The principles of rehabilitation are extensively presented, along with indications and important technical aspects of selected surgical procedures. General principles and specific protocols of postoperative rehabilitation are also summarized. CONCLUSIONS/RECOMMENDATIONS: Rotator cuff and impingement injuries in the athletic population are multifactorial in etiology, exhibiting significant overlap with glenohumeral instability. Nonoperative treatment is successful in most athletic patients with rotator cuff and impingement injuries. When nonoperative treatment fails, arthroscopic surgical techniques such as rotator cuff repair and subacromial decompression may be successful in returning the athlete to competition.

Journal Article↗

PubMed1999

Investigation of liquid-solid hydrodynamic boundary layers and oxygen requirements in hairy root cultures.

Rates of oxygen uptake, growth and alkaloid production by hairy roots in submerged culture were investigated using a recirculation reactor allowing operation at high liquid velocities for removal of hydrodynamic boundary layers. Measurements were performed at dissolved oxygen tensions of 31-450% air saturation. Critical oxygen concentrations for Atropa belladonna hairy roots were above air saturation, viz. 100-125% air saturation for oxygen uptake and 150% air saturation for growth, demonstrating that these roots cultivated in reactors with air sparging are oxygen-limited. The critical oxygen tension for oxygen uptake by Solanum aviculare hairy roots was 75% air saturation. Both the specific oxygen uptake rate and specific growth rate of A. belladonna hairy roots were dependent on the mass (g dry weight) of roots present; even in the absence of boundary layers, growth did not remain exponential over the entire culture period. Cryo-scanning electron microscopy showed that hairy roots grown submerged in liquid medium were covered with thick layers of hydrated mucilage and root hairs, representing a significant additional barrier to oxygen transfer. Roots protruding out of the liquid medium showed no evidence of mucilage accumulation. The specific oxygen demand of A. belladonna root tips was 3.3-11.5 times higher than for the remainder of the roots, the ratio increasing as the dissolved oxygen tension was reduced. Specific growth rates, biomass yields from sugar, and atropine levels were maximum at around 150% air saturation, but decreased significantly with oxygen concentrations above ca. 200%.

Atropa belladonna↗