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Biomedical subjects

David G Lewallen

Publications and source records attributed to David G Lewallen.

At least 19 recordsLinked to original sources
PubMed2006

Lack of detection of human retrovirus-5 proviral DNA in synovial tissue and blood specimens from individuals with rheumatoid arthritis or osteoarthritis.

OBJECTIVE: Prior studies have suggested an association of human retrovirus 5 with rheumatoid arthritis. The purpose of this study was to determine if human retrovirus-5 proviral DNA is present in synovial tissue and blood specimens from patients with rheumatoid arthritis or osteoarthritis, or those without joint disease. METHODS: Synovial tissue and whole blood from 75 patients with rheumatoid arthritis, 75 patients with osteoarthritis, and 50 patients without a primary arthritis diagnosis were assayed by real-time quantitative polymerase chain reaction (PCR) using primers that amplify a 186-bp fragment of human retrovirus-5 proviral DNA. RESULTS: A total of 200 tissue specimens, 200 mononuclear cells, and 196 of 200 granulocyte specimens tested negative for human retrovirus-5 proviral DNA. No association between human retrovirus 5 and rheumatoid arthritis or osteoarthritis (P = 0.516) was identified. Granulocyte specimens from 4 patients, 2 with rheumatoid arthritis and 2 with osteoarthritis, yielded a low positive human retrovirus-5 proviral DNA signal (83-1,365 copies of human retrovirus-5 proviral DNA/ml blood). CONCLUSION: Contrary to prior reports, we did not find an association between human retrovirus 5 and rheumatoid arthritis or osteoarthritis using a real-time PCR assay. Our findings are consistent with the recent finding that human retrovirus 5 is actually rabbit endogenous retrovirus H.

Adolescent↗
PubMed2006

Total hip arthroplasty in patients with renal failure: a comparison between transplant and dialysis patients.

This study analyzed the outcome of total hip arthroplasty (THA) from a single institution of patients with renal failure, including renal dialysis patients (9 patients, 9 hips) and renal transplant patients (28 patients, 36 hips). There were 12 revisions and a 61% complication rate in the transplant group. In the dialysis group, 1 patient was revised, and there was a 33% complication rate. Transplant patients were younger, more active, and lived longer, but had higher cumulative rates of revision and complications with longer follow-up. Dialysis patients, in contrast, had a short survival but a lower rate of complications and revisions. These data differ from previous reports of acceptable outcomes with low complication rates of THA in transplant patients. Efforts to minimize complications in these patients are justified.

Adolescent↗
PubMed2006

Transsciatic foramen pedicle VRAM coverage of gluteal defects.

Tumors of the gluteal region are rare. Defects from resection often can be closed primarily. Some patients require local flaps such as a gluteus maximus V-Y advancement flap. Such flaps typically result in some muscle dysfunction. In addition, the use of local irradiated tissue may lead to wound complications and prolonged hospitalization. Avoiding local radiated tissue, such as the gluteal muscles, can be beneficial. We report our experience using a novel route by passage through the transsciatic foramen to transpose a pedicle vertical rectus abdominis myocutaneous flap. This regional option avoids gluteal muscle dysfunction and potential wound complication from irradiated tissue.

Adult↗
PubMed2006

Local antibiotic delivery with OsteoSet, DBX, and Collagraft.

Biodegradable local antibiotic delivery systems have gained interest for prophylaxis and treatment of musculoskeletal infections. We studied the biodegradable materials Osteo- Set, DBX and Collagraft for local delivery of vancomycin and gentamicin in vitro. We determined the antimicrobial activity of vancomycin and gentamicin after mixing with each biodegradable material and determined the release of each antimicrobial from each material in an intermittent flow chamber. Antimicrobial activity was expressed as percent of antimicrobial loaded into each sample that was detected; antimicrobial release was expressed as concentration (microg/mL) after timed intervals of chamber flow, peak concentration, area under the curve and percent antimicrobial recovered. Activity of vancomycin after mixing with Osteo- Set, DBX and Collagraft was > 73%. Activity of gentamicin after mixing with DBX was 100%; after mixing with OsteoSet and Collagraft it was reduced to < 61%. AUC0-48hrs of vancomycin was 469, 426 and 432 microg x hr/mL, and the AUC0-48hrs of gentamicin was 368, 306 and 301 microg x hr/mL after release from OsteoSet, DBX, and Collagraft, respectively. Recovered percentages of vancomycin were 39%, 11% and 25%, and recovered percentages of gentamicin were 39%, 9% and 23% after release from OsteoSet, DBX, and Collagraft, respectively. OsteoSet, DBX and Collagraft may be suitable for local delivery of vancomycin and gentamicin.

Absorbable Implants↗
PubMed2006

Intraoperative fractures of the acetabulum during primary total hip arthroplasty.

BACKGROUND: The intraoperative occurrence of an acetabular fracture is a rare complication of primary total hip arthroplasty. Previous reports have lacked a sufficiently large number of subjects to allow for an analysis of the causes and appropriate treatment of this problem. METHODS: Between 1990 and 2000, 7121 primary total hip arthroplasties were performed at our institution. We retrospectively reviewed the records in our Total Joint Registry and found that twenty-one patients (twenty-one hips) had sustained an intraoperative acetabular fracture. Nineteen of these patients (nineteen hips) had been followed until revision or for a minimum of two years (mean duration of follow-up, forty-four months). We evaluated the anatomic location, cause, treatment, and outcome of the fractures. Acetabular component designs were categorized as modular, nonmodular (monoblock), true hemispherical, or elliptical, and then each design was analyzed for fracture risk. RESULTS: No fractures occurred in association with cemented acetabular components. The fracture rate associated with uncemented components was 0.4%. In seventeen hips, the acetabular component was judged to be stable despite the detection of a fracture and the cup was retained. In four hips, the original cup was not stable and therefore was replaced with a design that allowed for supplemental screw fixation. All fractures united, and all cups demonstrated osseous ingrowth at the time of the most recent follow-up. Elliptical monoblock cups were associated with a significantly higher fracture rate than were elliptical modular cups (p < 0.0001) and hemispherical modular cups (p < 0.0001). There was no significant difference between elliptical modular and hemispherical modular components with regard to the fracture rate. CONCLUSIONS: Acetabular fracture during primary total hip arthroplasty is a rare complication of acetabular fixation without cement. In the present series, retention of a stable cup was associated with uneventful osseous ingrowth and excellent early-term outcomes. We found a high rate of fracture in association with the use of monoblock elliptical components. LEVEL OF EVIDENCE: Therapeutic Level III.

Acetabulum↗
PubMed2006

"Broken heart syndrome" after separation (from OxyContin).

We describe a 61-year-old woman with "broken heart syndrome" (Takotsubo-like cardiomyopathy) after abrupt postsurgical withdrawal of OxyContin. Her medical history was remarkable for long-term opiold dependence associated with the treatment of multi-Joint degenerative osteoarthritis. The patient presented to the emergency department 1 day after discharge from the hospital following total knee arthroplasty revision with acute-onset dyspnea and mild chest pain. She had precordial ST-segment elevation characteristic of acute myocardial infarction and elevated cardiac biomarkers. Emergency coronary angiography revealed no major coronary atherosclerosis. However, the left ventricular ejection fraction was severely decreased (26%), and new regional wall motion abnormalities typical of broken heart syndrome were noted. In addition to resuming her opioid therapy, she was treated supportively with bilevel positive airway pressure, diuretic therapy, morphine, aspirin, metoprolol, enalaprilat, intravenous heparin, nitroglycerin infusion, and dopamine infusion. Ventricular systolic function recovered completely by the fourth hospital day. To our knowledge, broken heart syndrome after opioid withdrawal has not been reported previously in an adult. Our case illustrates the importance of continuing adequate opiate therapy perioperatively in the increasing number of opioid-dependent patients to prevent potentially life-threatening complications such as broken heart syndrome.

Analgesics, Opioid↗
PubMed2005

Chondroconductive potential of tantalum trabecular metal.

Mesenchymal stem cells or chondrocytes have been implanted into joints in biodegradable matrices in order to improve the quality of healing cartilage defects; however, insufficient biomechanical strength of the construct at implantation is a limiting factor for clinical application. Logically, a construct with better biomechanical characteristics would provide better results. Tantalum trabecular metal (TTM) is osteoconductive and mechanically similar to subchondral bone. The objective of this pilot study was to determine if TTM is also chondroconductive. Small sections of TTM were cultured with emu and canine chondrocytes in static and dynamic culture environments. The sections cultured in dynamic bioreactors were diffusely covered with a cartilaginous matrix. Sections cultured in static conditions had no growth. Histologic evaluation from emu and canine dynamic cultures showed tissue that was heavily populated with mesenchymal cells that resembled chondrocytes, and glycosaminoglycan staining that was distributed throughout the matrix. Type II collagen content in the canine dynamic culture was 84% by SDS-PAGE. Tantalum trabecular metal is chondroconductive in vitro in a dynamic environment when cultured with adult canine or emu chondrocytes. This technology could be expanded to determine if cartilaginous-metallic constructs may be used for joint resurfacing of osteoarthritic joints.

Animals↗
PubMed2005

Radiographic evaluation of a monoblock acetabular component: a multicenter study with 2- to 5-year results.

Serial radiographs of a porous tantalum monoblock acetabular cup design were evaluated for cup stability and signs of successful osteointegration. Of 574 primary consecutive total hip replacements in 542 patients performed by 9 surgeons at 7 hospitals, 414 cases were available for minimum 2-year follow-up. Follow-up averaged 33 months and ranged from 24 to 58 months. Postoperative radiographs revealed acetabular gaps in 100 zones in 80 (19%) hips: 29 in zone I, 67 in zone II, and 4 in zone III. At last follow-up, 84 (84%) of the zones with gaps completely filled in, and all 4- and 5-mm gaps filled in. There was no progression of any postoperative gap, no evidence of continuous periacetabular interface radiolucencies, no evidence of lysis, and no revisions for loosening. Although these short-term results are encouraging, further follow-up will be required to assess whether the monoblock design and the low modulus of elasticity of porous tantalum will reduce the incidence of periacetabular stress shielding and occurrence of osteolysis.

Acetabulum↗
PubMed2005

Perioperative morbidity and 30-day mortality after intertrochanteric hip fractures treated by internal fixation or arthroplasty.

The conventional treatment for intertrochanteric hip fracture is open reduction and internal fixation. However, hip arthroplasty is occasionally performed. The objective of this study was to determine the 30-day mortality for patients with intertrochanteric hip fracture treated with open reduction, internal fixation, or hip arthroplasty. The mortality rate for patients treated with arthroplasty at 4.8% (23/478) was slightly, but not significantly, higher than that for patients treated with open reduction and internal fixation at 4.5% (62/1395). However, more of the patients in the arthroplasty group exhibited serious intraoperative cardiorespiratory disturbances (62% vs 22%) and died in the hospital (77% vs 35%) when compared with the patients in the open reduction and internal fixation group. Although the incidence of 30-day mortality in these groups was not significantly different, the patients in the arthroplasty group were more likely to have a complicated intraoperative course and die in the hospital.

Adult↗
PubMed2005

Canine carpal joint fusion: a model for four-corner arthrodesis using a porous tantalum implant.

PURPOSE: Interest has focused on porous materials that promote bony ingrowth. In this study a porous tantalum implant was used as an adjunct to intercarpal stabilization in a canine model of wrist arthrodesis. METHODS: A defect was created at the junction of the radiocarpal, ulnocarpal, and fourth carpal bones, analogous to a four-corner fusion site in humans. A tantalum cylinder was press-fit and stabilized with K-wires. Controls were represented by creating the defect without implant placement. Animals were killed at 4, 8, and 12 weeks. RESULTS: Histology showed bony ingrowth as early as 4 weeks and mechanical testing showed a statistically significant increase in strength of the construct over time. Controls failed to achieve union at any time point. CONCLUSIONS: The implant served as an adjunct to stabilization of the carpus in this model of four-corner fusion, suggesting a novel application of this material in conditions in which bone graft has been required previously. This study represents a preliminary investigation of the use of a tantalum device for intercarpal stabilization; it does not compare this technique with conventional methods.

Animals↗
PubMed2005

Two-incision THA had modest outcomes and some substantial complications.

UNLABELLED: Proponents of two-incision total hip arthroplasty suggest the technique is minimally invasive and promotes rapid rehabilitation with a low prevalence of complications. We applied the two-incision total hip arthroplasty technique to a consecutive group of unselected patients with primary degenerative arthritis to determine the technical difficulty of the operation as measured by the operative time compared with a standard posterior approach, the safety of the operation as measured by the prevalence of complications compared with a standard posterior approach, and the early functional outcome measured by the time to return to activities of daily living as compared with a previous study of the two-incision technique in selected younger patients. The 80 patients included 45 women and 35 men with a mean age of 70.5 years. The patients treated with a two-incision method had longer operative times and substantially more complications than did the patients treated with a standard posterior approach. The early functional outcomes in this group of unselected patients were modest when compared with the previous results in selected younger patients. Patient and surgeon enthusiasm for the potential benefits of the two-incision total hip arthroplasty should be tempered by the modest early outcomes and the substantial prevalence of complications found in this group of typical patients having total hip arthroplasty. LEVEL OF EVIDENCE: Prognostic study, Level III (retrospective study). See the Guidelines for Authors for a complete description of levels of evidence.

Adult↗
PubMed2005

Quadriceps tendon rupture after total knee arthroplasty. Prevalence, complications, and outcomes.

BACKGROUND: There is relatively little information about quadriceps tendon tears after total knee arthroplasty. The purpose of this study was to determine the prevalence of this condition and the outcomes of patients who had a tear of the quadriceps tendon after a total knee arthroplasty. METHODS: From a cohort of 23,800 primary total knee arthroplasties, we identified twenty-four patients who had a rupture of the quadriceps tendon postoperatively. Ten additional patients had the total knee arthroplasty done elsewhere and were referred for care after sustaining a tear of the quadriceps tendon. Thus, the study group consisted of thirty-four patients, and all had at least two years of follow-up. Eleven patients had a complete tear, and twenty-three had a partial tear. RESULTS: The prevalence of a quadriceps tendon tear after total knee arthroplasty was 0.1% (twenty-four of 23,800). Seven patients with a partial tear were treated nonoperatively, and all had a satisfactory outcome. One patient with a complete tear was treated nonoperatively and had an unsatisfactory result. Of the ten patients treated operatively after a complete tear, four subsequently had rerupture of the repaired tendon and four had a satisfactory outcome. Of the sixteen patients with a partial tear treated operatively, only one had rerupture and twelve had a satisfactory outcome. Complications occurred in eleven of the twenty-six patients managed operatively. CONCLUSIONS: The prevalence of complications was high, and the outcomes were poor for seven of the eleven patients who had a complete quadriceps tendon tear after total knee arthroplasty. Patients who sustained a partial tear and were treated nonoperatively had no complications and had uniformly good outcomes.

Adult↗
PubMed2005

Early postoperative transverse pelvic fracture: a new complication related to revision arthroplasty with an uncemented cup.

BACKGROUND: Uncemented hemispherical cups are commonly used to revise failed acetabular total hip components, even in the presence of marked acetabular bone loss. The purpose of the present study was to report a new complication of acetabular component revision with an uncemented hemispherical cup. METHODS: We retrospectively reviewed the records of seven patients (seven hips) in whom an early postoperative transverse acetabular fracture had developed following the implantation of an uncemented trabecular metal cup for the revision of a failed acetabular component. All patients were female. The average age was 63.6 years. The reason for acetabular revision was aseptic loosening of the original cup in five patients and reimplantation after a previous resection arthroplasty in the remaining two. The average cup size used for revision was 58 mm. In two hips, additional modular acetabular metal augments were used to restore the acetabular rim. RESULTS: The average postoperative time to diagnosis of a transverse acetabular fracture was eight months. Five of the seven patients presented with a marked acute increase in pain and a new displaced transverse acetabular fracture (pelvic discontinuity) that was visible on plain radiographs. Two patients were asymptomatic but had a nondisplaced transverse acetabular fracture. In all seven patients, the trabecular metal socket appeared radiographically to be well fixed to part of the pelvis. The five patients with a displaced fracture were managed with additional surgery to stabilize the fracture. CONCLUSIONS: To our knowledge, early postoperative transverse pelvic fractures following revision of the acetabular component have not been reported previously. The most likely causes of this complication are further weakening of the remaining pelvic bone stock as a result of the reaming required to obtain a secure fit of a large-diameter hemispherical socket and the cyclic stresses on the weakened bone with resumption of walking. It is unlikely that the fractures occurred intraoperatively because in each case the socket remained well fixed to one of the pelvic fragments.

Adult↗
PubMed2004

Comparison of wear and osteolysis in hip replacement using two different coatings of the femoral stem.

We compared the clinical and radiographic results of two matched series of total hip arthroplasties, one with hydroxyapatite-coated femoral stems, the other with a similar but porous-coated femoral stem. The prevalence of radiographic osteolysis was 16% in hips with hydroxyapatite-coated stems and 43% in hips with porous-coated femoral stems. In hips with hydroxyapatite-coated stems, osteolysis was always limited to Gruen zones 1 and 7. In contrast, distal osteolysis was present around 26% of the porous-coated stems. At 7 years, the survival-free rate of distal osteolysis was 100% in hips with hydroxyapatite-coated stems but 90% in hips with porous-coated stems (p=0.04). Circumferential hydroxyapatite coating of the femoral component reduced the occurrence of osteolysis and eliminated distal osteolysis at 5-10 years of follow-up. In addition, hydroxyapatite coating did not alter the wear rate.

Adult↗
PubMed2004

The modular segmental kinematic rotating hinge for nonneoplastic limb salvage.

From January 1980 to July 1998, 25 patients (26 knees) were treated with an arthroplasty using a Modular Segmental Kinematic Rotating Hinge total knee prosthesis for nonneoplastic limb salvage. The indications included: nonunion of a periprosthetic femur fracture (11 knees), severe bone loss and ligamentous instability (eight knees), nonunion of a supracondylar femur fracture (four knees), acute periprosthetic fracture (one knee), fracture of a previous hinge (one knee), and prior resection arthroplasty (one knee). The average age of the patients was 72.3 years. Twenty-two arthroplasties were revisions. The average followup was 58.5 months. At the latest followup, knee extension averaged 2.4 degrees and flexion averaged 93.6 degrees. The Knee Society knee score improved from an average of 45.4 preoperatively to 75.5. Preoperatively, functional scores averaged 8.6 and improved to 25. Complications occurred in eight patients. The most common was deep infection (five patients). The use of the Modular Kinematic Rotating Hinge for nonneoplastic limb salvage represents a small proportion (0.14%) of all primary and revision knee arthroplasties done at our institution. The indications for the surgery are for a highly complex and small subset of patients. The patients in the current study gained significant improvement in overall range of motion, Knee Society knee scores, and functional scores when this prosthesis was used.

Aged↗
PubMed2004

Gentamicin and vancomycin do not impair experimental fracture healing.

The purpose of this study was to determine whether gentamicin or vancomycin impair experimental fracture healing in rats. Forty-one male Wistar rats were divided into three groups, receiving either 1.5 mg/kg of gentamicin intramuscularly twice daily for 3 weeks (n = 15), 25 mg/kg of vancomycin intraperitoneally twice daily for 3 weeks (n = 14), or no treatment (n = 12), starting 7 days after production of closed, nondisplaced, bilateral femoral fractures. The mean 30 minute serum concentrations of gentamicin and vancomycin were 4.5 microg/mL and 35.1 microg/mL, respectively. Biomechanical and radiographic studies were used to evaluate fracture healing. Torsional strength testing of fracture callus exposed to gentamicin and vancomycin was similar (437 and 424 N-mm, respectively) to controls (334 N-mm). Radiographs showed similar healing in control animals (Goldberg score, 2.3) compared with rats treated with gentamicin and vancomycin (Goldberg score, 2.6 in both groups). Results of this study do not show impaired healing of experimental fractures after exposure to gentamicin or vancomycin (such as has been reported after exposure to quinolones).

Animals↗