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Biomedical subjects

David H Kim

Publications and source records attributed to David H Kim.

11 recordsLinked to original sources
PubMed2003

Prevention of postlaminectomy epidural fibrosis using bioelastic materials.

STUDY DESIGN: The use of elastic protein-based polymers for the prevention of epidural fibrosis following lumbar spine laminectomy was investigated in a rabbit model. OBJECTIVES: To determine the safety and efficacy of two bioelastic polymers in matrix and gel forms as interpositional materials in preventing postlaminectomy epidural fibrosis. SUMMARY OF BACKGROUND DATA: Postlaminectomy epidural fibrosis complicates revision spine surgery and is implicated in cases of "failed back syndrome." Materials employed as mechanical barriers to limit tethering of neural elements by the fibrosis tissue have met with little success. A recent family of protein-based polymers, previously reported to prevent postoperative scarring and adhesions, may hold promise in treating this condition. METHODS: Sixteen female New Zealand White rabbits underwent laminectomy at L4 and L6. Two polymer compositions, each in membrane and gel forms, were implanted at a randomly assigned level in four rabbits each, with the remaining level serving as an internal control. The animals were killed at 8 weeks, and qualitative and quantitative histology and gross pathologic examination were performed for both the control and the experimental sites to assess the polymers' efficacy in preventing dorsal epidural fibrosis. RESULTS: The use of the polymers caused no adverse effects. Compared to the control sites, both polymers in either gel or membrane form significantly reduced the formation of epidural fibrosis and its area of contact with the dura postlaminectomy. However, no significant difference in efficacy was detected between either the polymers or their respective forms in preventing epidural fibrosis. CONCLUSIONS: The selected compositions of biosynthetic, bioelastic polymers were safe and effective in the limiting the direct contact and consequent tethering of the underlying neural elements by the postlaminectomy epidural fibrosis in rabbits.

Animals↗
PubMed2003

Acute sports-related spinal cord injury: contemporary management principles.

Improvements in helmet and equipment design have led to significant decreases in overall injury incidence, but no available helmet can prevent catastrophic injury to the neck and cervical spine. The most effective strategy for preventing this type of injury appears to be careful instruction, training, and regulations designed to eliminate head-first contact. The incidence of football-related quadriplegia has decreased from a peak of 13 cases per one million players between 1976 and 1980 to 3 per million from 1991 to 1993, mostly as a result of systematic research and an organized effort to eliminate high-risk behavior. An episode of transient quadriparesis does not appear to be a risk factor for catastrophic spinal cord injury. Torg reported that 0 of 117 quadriplegics in the National Football Head and Neck Injuries Registry recalled a prior episode of transient quadriparesis, and 0 of the 45 patients originally studied in his transient quadriparesis cohort have subsequently suffered quadriplegia. The significance of developmental spinal stenosis is unclear. Plain radiographic identification of a narrow spinal canal in a player sustaining cervical cord neurapraxia warrants further evaluation by MRI to rule out functional stenosis. The presence of actual cord deformation or compression on MRI should preclude participation in high-risk contact or collision sports.

Acute Disease↗
PubMed2003

Avulsion fractures of the medial tubercle of the posterior process of the talus.

Avulsion fracture of the medial tubercle of the posterior process of the talus occurs after forceful dorsiflexion-pronation of the ankle. We evaluated five patients who had sustained this fracture while participating in sporting activities. Two patients were correctly diagnosed acutely and treated with immobilization and limited weightbearing. Avulsion fractures in the remaining three patients went undiagnosed acutely. This group was treated with delayed operative excision for persistent posteromedial ankle pain. The patients were evaluated at a mean follow-up of 35 months using the AOFAS Ankle-Hindfoot Scale. The two patients diagnosed and treated acutely achieved excellent results. The three patients with missed fractures did poorly, yet achieved comparable results after late excision. Our results suggest that prompt diagnosis and appropriate management yields reliably good outcomes. Untreated avulsion fractures predictably do poorly. For these patients, late excision can provide significant functional and symptomatic improvement.

Adult↗
PubMed2003

Osteoporotic vertebral compression fractures.

Osteoporotic vertebral compression fractures are a commonly encountered clinical problem. Although the majority of patients with this injury experience a benign and self-limited course of gradually resolving pain, a significant number continue to experience chronic pain and disability. In evaluating a patient with a vertebral compression fracture, the differential diagnosis must consider not only osteoporosis, but also various causes of osteomalacia, endocrinopathy, and malignancy. Accumulation of multiple compression fractures and increased thoracolumbar kyphosis are associated with a poor prognosis. Multiple medical treatments--including hormone replacement therapy, calcitonin, and bisphosphonates--are effective in maintaining or increasing bone mass and reducing the risk of compression fracture. Conventional treatment in the form of pain medication, activity limitation, and occasionally bracing is effective in returning most patients to their previous level of functioning. When therapies fail, patients may be considered for minimally invasive treatments such as vertebroplasty or kyphoplasty. Surgery, although enormously challenging because of poor underlying health status and structurally weak bone, may be the last resort for a small percentage of patients experiencing progressive deformity or neurologic deficit.

Aged↗
PubMed2002

Foot fractures frequently misdiagnosed as ankle sprains.

Most ankle injuries are straightforward ligamentous injuries. However, the clinical presentation of subtle fractures can be similar to that of ankle sprains, and these fractures are frequently missed on initial examination. Fractures of the talar dome may be medial or lateral, and they are usually the result of inversion injuries, although medial injuries may be atraumatic. Lateral talar process fractures are characterized by point tenderness over the lateral process. Posterior talar process fractures are often associated with tenderness to deep palpation anterior to the Achilles tendon over the posterolateral talus, and plantar flexion may exacerbate the pain. These fractures can often be managed nonsurgically with nonweight-bearing status and a short leg cast worn for approximately four weeks. Delays in treatment can result in long-term disability and surgery. Computed tomographic scans or magnetic resonance imaging may be required because these fractures are difficult to detect on plain films.

Ankle Injuries↗
PubMed2002

Update on use of instrumentation in lumbar spine disorders.

The past 20 years have witnessed significant changes in the indications for and use of instrumentation in lumbar spine surgery. Absolute indications for surgical instrumentation include cases of clearly defined instability that commonly occur in the setting of trauma, tumour and infection. Relative indications for instrumentation must consider the clinical context and individual patient characteristics but may include cases of spondylolisthesis, junctional stenosis and pseudarthrosis. The use of instrumentation in the surgical treatment of degenerative disc disease is prevalent but remains highly controversial. Pedicle screws and interbody cages represent alternative forms of instrumentation with substantial clinical evidence supporting their safety and efficacy when applied in the correct clinical settings. Minimally invasive and computer-assisted surgical techniques have shown promising early results but must be subject to longer-term scrutiny. The development of prosthetic disc replacements is an exciting area of research, but clinical results have not approached the success currently enjoyed by hip and knee prostheses, and these devices should be considered experimental. One of the goals of instrumentation is to enhance the rate of spinal fusion. However, achievement of solid radiographic fusion does not guarantee a clinically successful outcome and, conversely, excellent results can be obtained in the setting of radiographic pseudarthrosis. The most important determinant of favourable surgical outcome is appropriate patient selection through a sound understanding of surgical indications.

Humans↗
PubMed2002

Involvement of CYP3A in the metabolism of eplerenone in humans and dogs: differential metabolism by CYP3A4 and CYP3A5.

In vitro studies were conducted to identify the major metabolites of eplerenone (EP) and the cytochrome p450 (p450) isozymes involved in its primary oxidative metabolism in humans and dogs. The major in vitro metabolites were identified as 6 beta-hydroxy EP and 21-hydroxy EP in both humans and dogs. EP was metabolized by cDNA-expressed human CYP3A4 and dog CYP3A12 but only minimally by human CYP3A5. In human microsomes, inhibition of total metabolism by the CYP3A-selective inhibitors ketoconazole, troleandomycin, and 6',7'-dihydroxybergamottin, each at 10 micro M concentration, was 83 to 95%, whereas inhibition with inhibitors selective for other p450 isozymes was minimal. In dog liver microsomes, the percentages of inhibition were 53 to 76% with the CYP3A-selective inhibitors. A monoclonal anti-CYP3A4 antibody inhibited EP metabolism by 84%, whereas other monoclonal antibodies had minimal effects. The formation of 6 beta-hydroxy and 21-hydroxy metabolites in human liver microsomes was best correlated with CYP3A-selective dextromethorphan N-demethylation and testosterone 6 beta-hydroxylation activities. EP moderately inhibited only CYP3A (testosterone 6 beta-hydroxylase) activity in human liver microsomes by 23, 34 and 45% at concentrations of 30, 100, and 300 micro M, respectively. With human microsomes, the V(max) and K(m) for 6 beta-hydroxylation and 21-hydroxylation were 0.973 nmol/min/mg and 217 micro M, and 0.143 nmol/min/mg and 211 micro M, respectively. The human hepatic clearance calculated from total in vitro EP metabolism was 2.30 ml/min/kg, which agrees with in vivo data. In conclusion, 6 beta- and 21-hydroxylation of EP is primarily catalyzed by CYP3A4 in humans and CYP3A12 in dogs. Also, it is unlikely that EP would substantially inhibit the metabolism of other drugs that are metabolized by CYP3A4 or other p450 isoforms.

Animals↗
PubMed2002

Coxa saltans externa treated with Z-plasty of the iliotibial tract in a military population.

Coxa saltans, or snapping hip, can be attributable to a number of causes. Coxa saltans externa typically occurs when the thickened portion of the iliotibial band snaps over the greater trochanter as the hip is flexed. This condition generally resolves with a course of nonoperative treatment. We have treated three patients with Z-plasty of the iliotibial band, which has the highest published success rate in the English language literature. Only one of three patients was able to return to full activities postoperatively. In our small series, this method of surgical treatment in an active duty military population yielded less than optimal results.

Adult↗
PubMed2002

Os acromiale.

Explore the source record for details and available documents.

Acromion↗
PubMedDate not supplied

Patient positioning for shoulder arthroscopy based on variability in lateral acromion morphology.

The purpose of this article is to highlight the variability among shoulders in the relationship between the lateral acromion and the humeral head and to describe how this variability may influence a surgeon's choice of patient positioning for shoulder arthroscopy. In cases of increased lateral coverage of the humeral head by the acromion, arthroscopic access to the superior aspect of the glenoid through lateral portals becomes increasingly difficult because of a narrowed corridor of approach. Placing the ipsilateral arm in traction will lower the station of the humeral head and widen the arthroscopic corridor of approach to the superior labrum. Based on preoperative assessment of lateral acromion morphology, if the surgeon determines that inferior displacement of the humeral head of 25% or more of the humeral head diameter will be necessary to achieve adequate arthroscopic accessibility of the superior glenoid through lateral portals, we recommend the lateral decubitus position with continuous traction on the ipsilateral arm over the beach-chair position.

Acromion↗