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Biomedical subjects

P L Lewis

Publications and source records attributed to P L Lewis.

At least 19 recordsLinked to original sources
PubMed2005

Arthrofibrosis following total knee replacement; does therapeutic warfarin make a difference?

Arthrofibrosis following total knee replacement (TKR) is a relatively common complication which results in a reduction in knee range of movement and patient dissatisfaction. A retrospective study examined the relationship between anticoagulation with therapeutic warfarin and rates of arthrofibrosis following TKR. Arthrofibrosis was defined as less than 80 degrees of knee flexion 6-8 weeks post-TKR. Patients were warfarinised if they had a history of thrombophilic tendencies or medical conditions necessitating anti-coagulation, rather than as routine thromboprophylaxis. All other patients received thromboprophylaxis using low molecular weight heparin. A total of 728 patients underwent 874 primary TKR between 1993 and 2002 in one centre, performed by four surgeons. Mean age was 68 years (range 48-89 years) and there were 483 female and 391 male knees. Eighty cases were warfarinised post-operatively (53 female, 27 male). Overall, 83 of 874 TKRs (9%) had arthrofibrosis (57 female, 26 male) requiring manipulation under anaesthetic (MUA). In the warfarinised group, 21 knees (26%) had an MUA (15 female, 6 male). This compared to 62 cases (8%) requiring MUA in the non-warfarinised group (42 female, 20 male). There was a statistically significant difference on Fisher's exact testing (P<0.0001) between groups. Following MUA, knee flexion improved in 95% cases to a minimum 95 degrees but 8 cases had a fixed flexion deformity of 5-10 degrees . In conclusion, therapeutic warfarinisation post-TKR leads to a statistically greater chance of the patient developing arthrofibrosis compared to prophylactic low molecular weight heparin and that patients should be counseled appropriately.

Aged↗
PubMed2004

Chondral degeneration and therapeutic hip arthroscopy.

Therapeutic hip arthroscopy for the treatment of chondral degeneration remains controversial. A retrospective cohort study examined 70 patients of mean age 47 (range 22-87) years who had undergone hip arthroscopy and assessed them for evidence of chondral degeneration using radiological and arthroscopic means. Clinical outcome was assessed using a modified Farjo and Glick classification. Thirty-nine patients had evidence of chondral degeneration on arthroscopy with or without radiological diagnosis, and 31 had alternative pathology. If patients were found to have chondral degeneration at arthroscopy, they were significantly more likely to have a poor clinical result than if an alternative diagnosis such as a loose body or labral tear was made (p<0.0001). Patients with evidence of degenerative changes on plain hip radiographs were significantly more likely to have a poor clinical result following hip arthroscopy than patients with unremarkable hip radiographs (p<0.0001). Therapeutic hip arthroscopy for osteoarthritis should be used with caution, as a poor clinical result is significantly more likely compared to other pathologies such as a labral tear or loose body.

Adult↗
PubMed2004

Patient-perceived outcome measures following unicompartmental knee arthroplasty with mini-incision.

We reviewed 150 patients (183 knees) who underwent mini-incision unicompartmental knee arthroplasty (Oxford). Mean age was 71.5 (36-92) years. Review was conducted at least 12 months following surgery. To assess results, we used the Oxford knee questionnaire, modified Grimby score, return to sport and work, knee "normality" and patient general health. The mean Oxford knee score was 22.17 (range 12-54). Kneeling scored worse than other activities. No significant age or gender difference was found. Mean modified Grimby score was 3.89, equating to moderate exercise less than 2 h a week. Patients with "artificial-feeling" knees had significantly worse scores than patients with normal/near-normal-feeling knees. Patients who returned to/increased sporting activity had better Oxford scores than those who did not. Ninety-four percent of patients working pre-operatively returned to work. Sixty-seven percent continued at the same level of or increased sporting activity. Oxford knee scores and return to sport compared well to published data. Results regarding modified Grimby score, return to work and pain relief were encouraging. The best results were achieved in active patients who felt their health was good and their knee felt normal or near normal following surgery.

Adult↗
PubMed2001

Is the quality of surgical residency applicants deteriorating?

BACKGROUND: Among directors of general surgery residencies, there is a concern that the quality of medical students applying to surgical residencies is declining. METHODS: Quality of surgical applicants was assessed by several methods including subjective opinions determined by survey and by objective data including student United States Medical Licensing Examination (USMLE) scores of matched candidates. The number of applicants interviewed, total interviews granted, proportion of Alpha Omega Alpha (AOA) students, and the rank order of the candidates matched was obtained by survey. The survey included data on postgraduate year 1 (PGY-1) residents from July 1996 to July 1999. Three mailings were made to 226 US surgical residency programs. RESULTS: Data were obtained from 90 programs. Surgery program directors disagreed with a survey statement that overall quality of applicants had declined (P <0.01), but agreed with a statement that activities of medical schools to enroll graduating students into primary care had hurt recruitment (P <0.001). Objective data revealed no change in mean USMLE part I scores of PGY-1 residents over the 4 years (P = 0.265, power = 0.81). There was no change in proportion of matched residents who were AOA over time. The mean score of all new PGY-1 residents, the rank of the first matched resident, the rank of the last ranked resident, and proportion of AOA students was higher in programs with five or more categorical spots when compared with programs of at most four (P <0.001). Across all programs, there was a trend to go lower on the rank list to fill categorical positions over time (P <0.001). CONCLUSIONS: There is a perception that medical school policies act to discourage recruitment of quality medical students into general surgery programs, and surgery programs are going deeper into their rank lists to fill categorical positions. However, the average USMLE part I score of applicants to surgical residencies and proportion of AOA applicants has not decreased.

Data Collection↗
PubMed2001

A long-term review of a modified Evans procedure.

Of 111 primary ankle ligament arthroplasties (modified Evans procedure) performed between 1983 and 1994, we were able to identify 89 patients (94 ankles) for follow-up. All were under 50 years of age. Two had died and one refused to co-operate; 86 patients (91 ankles) were therefore reviewed, 25 by telephone and the remainder by clinical examination with all but three also undergoing radiological review. Of the 91 ankles, 70 had no or very mild pain and 72 had no or rare episodes of instability and when considered together only 59 (65%) had no or mild pain and minimal instability. The results were supported by the Karlsson grading system. Clinical examination showed that 17 of the 66 ankles examined had increased inversion, while 21 had some limitation of inversion. Early degenerative changes were seen in 11 ankles, although only four had subtalar changes. These results show that this procedure does not give universally good clinical results. Patient satisfaction, however, was high with 97.7% being willing to undergo the same procedure if their other ankle became similarly affected.

Adult↗
PubMed2000

Maximizing tolerance of enteral nutrition in severely injured trauma patients: a comparison of enteral feedings by means of percutaneous endoscopic gastrostomy versus percutaneous endoscopic gastrojejunostomy.

BACKGROUND: Intolerance of enteral nutrition interrupts caloric balance and increases hospital costs. This study proposes that enteral feeding by percutaneous endoscopic gastrojejunostomy (PEGJ) provides continuous uninterrupted nutrition with greater consistency than percutaneous endoscopic gastrostomy (PEG). METHODS: This prospective nonrandomly assigned study was conducted at a Level I trauma center from December of 1997 through October of 1998. All feeding tubes were placed by trauma/critical care surgeons for nutritional support. Feeding course was monitored for 14 days from time of tube placement. Demographic data and outcome variables compared were age, sex, Injury Severity Score, Abbreviated Injury Score, hospital length of stay, number of days to reach nutritional goal feedings, caloric goal, protein goal, cc/hr at goal, total parenteral nutrition usage, complications, and hospital charges. Statistical analyses used the independent samples t test, Cox regression, and Pearson chi2 with significance level set at 0.05. RESULTS: Patients receiving enteral nutrition by PEGJ reached nutritional goal sooner than patients who received enteral nutrition by PEG (p = 0.02). Thirty-seven of 46 PEGJ patients (80%) were at goal rate at day 3, whereas 28 of 43 PEG patients (65%) were at goal on day 3. Nine of 43 PEG patients (21%) and 3 of 46 PEGJ patients (7%) failed to reach goal within 14 days. CONCLUSION: This study suggests that enteral nutrition delivered by means of PEGJ is better tolerated than enteral nutrition delivered by means of PEG in trauma patients with no abdominal conditions that preclude percutaneous feeding tube placement.

Adolescent↗
PubMed2000

The evaluation of subatmospheric pressure and hyperbaric oxygen in ischemic full-thickness wound healing.

We evaluated the efficacy of subatmospheric pressure and hyperbaric oxygen (HBO) as adjuncts in the treatment of hypoxic full-thickness wounds in a rabbit model. We hypothesized that subatmospheric pressure and HBO independently are effective in improving wound healing in the ischemic wound model and that when they are used in combination there is an increased positive effect on wound healing. Using a standard ischemic wound model four full-thickness wounds were created on each ear of 41 male New Zealand white rabbits (N = 82 ears). On each rabbit one ear was dressed with the vacuum-assisted closure (VAC) device and connected to suction; the other was dressed identically without the suction and suction tubing. Twenty rabbits were treated with HBO daily for 10 days at 2.0 atmospheres absolute for 90 minutes plus descent and ascent times. Necropsy on all rabbits was performed on postoperative day 10. Four ischemic wound treatment groups were evaluated: Group 1 (N = 21) VAC dressing alone; Group 2 (N = 20) VAC dressing plus HBO; Group 3 (N = 21) VAC dressing to suction alone; and Group 4 (N = 20) VAC dressing to suction and HBO. Using light microscopy a veterinary pathologist blinded to treatment groups quantified peak granulation tissue, granulation tissue gap, and epithelialization tissue gap. Data were analyzed by analysis of variance with significance indicated by P < 0.05. Statistical significance was found in a comparison of VAC dressing to suction and VAC dressing alone for peak granulation tissue and granulation tissue gap both with and without use of HBO. VAC device use appears to increase the rate of healing in a rabbit ischemic wound model. HBO therapy did not significantly affect the rate of healing in this model.

Analysis of Variance↗
PubMed1998

The pathogenesis of bone loss following total knee arthroplasty.

Bone loss following total knee arthroplasty (TKA) may be focal or diffuse. It may be caused mechanically, either by unloading of the bone leading to disuse osteoporosis, or by overloading of the bone leading to trabecular fractures and bone destruction. Osteolysis, instigated by an inflammatory reaction to particulate wear debris, is an important and common cause of bone loss after TKA. Less common, though sometimes dramatic, causes of bone loss are infection and osteonecrosis.

Arthroplasty, Replacement, Knee↗
PubMed1995

Screw osteolysis after cementless total knee replacement.

A comparative radiographic review of 217 cementless total knee replacements was done 4 years after surgery to look for radiographic change at the screw-bone interface. There were 102 Miller Galante I knee prostheses, 59 Miller Galante II prostheses, and 56 Anatomic Modular Knee prostheses studied. If the appearance of the screw-bone interface had changed, this was classified according to the width of the lucency. Two hundred sixty-five of the 851 screws that were studied showed some evidence of change, with 185 (21.7%) of the screws showing a cavitary appearance change. The AMK prosthesis showed the higher incidence of cystic and cavitary changes. Polyethylene debris is thought to be responsible for generation of osteolysis and the radiographic appearance change. Design of the components and particularly the polyethylene attachment mechanisms may be responsible for the differences in the frequencies of osteolysis.

Bone Screws↗
PubMed1994

A comparison of cold knife, CO2 laser, and electrosurgical loop conization in the treatment of cervical intraepithelial neoplasia.

Thirty patients with histologically confirmed high-grade squamous intraepithelial lesions (SIL) were treated by either cold knife, laser, or electrosurgical loop conization, all of which were performed under general anesthesia. The three methods were compared with respect to the immediate surgical complications, ease of performance, delayed complications, and quality of histologic specimens. The electrosurgical loop conization had decreased blood loss and reduced operative time and proved to be tissue sparing. There were no significant differences in the three groups in the persistence rates of cervical intraepithelial neoplasia (CN) after treatment. Histologic analysis revealed comparable coagulation artifact in the laser and electrosurgical loop groups that the cold knife group did not have. The endocervical component of the electrocautery showed extensive denudation and coagulation artifact that made recognition of CIN extremely difficult. We conclude that the electrocautery should be used only as an excisional method of the transformation zone for lesions well defined on the ectocervix, since it is unreliable if the lesion extends into the endocervix.

Adult↗
PubMed1993

The Miller-Galante knee prosthesis for the treatment of osteoarthrosis. A comparison of the results of partial fixation with cement and fixation without any cement.

In a prospective, non-randomized study of 344 patients who had 392 primary total knee replacements with a Miller-Galante I prosthesis for the treatment of osteoarthrosis, the results of partial fixation with cement (insertion of the tibial and patellar components with cement and of the femoral component without cement) were compared with those of fixation without any cement. Of the 392 knees, 183 (163 patients) had fixation without cement (Group I) and 209 (181 patients), with and without cement (Group II). The average duration of follow-up was three years (range, two to five years). Nine patients died during the follow-up period, but no others were lost to follow-up. Analysis of the knee scores, range of motion of the knee, radiographs, and rates of complications revealed no differences between the outcomes in the two groups during the follow-up period. The rate of complications due to problems related to the extensor mechanism was high in both groups: a reoperation was performed in fifteen (8 per cent) of the knees that had had fixation without cement and in nineteen (9 per cent) of those that had had both types of fixation. Thirteen patients had additional operative treatment for recurrent patellar dislocations; twelve patients, for abnormal wear of the polyethylene of the patellar component: two patients, for avulsion of the patellar ligament from the tibia; and two patients, for unexplained pain in the knee. In addition, there were eight patellar fractures (two of which led to a reoperation) and three deep infections (all of which led to a reoperation).

Adult↗
PubMed1990

Herbert screw fixation of osteochondral fractures about the knee.

Osteochondral fracture of the patella or femoral condyle may occur with patella dislocation. Accepted treatments of these fractures are excision or replacement. In this paper eight cases are described in which the Herbert Bone Screw system was used for fixation. Normal knee function was regained within 6 months and there were no reported recurrent dislocations. The advantages of this technique are that it is simple, there is little cartilage damage done during insertion, the screw is entirely buried and therefore does not interfere with the soft tissues, fixation is rigid enough to allow for the application of continuous passive motion to aid in cartilage repair, and re-operation for removal is not necessary.

Adolescent↗
PubMed1986

Metyrapone delays surfactant and antioxidant enzyme maturation in developing rat lung.

The surfactant system and the antioxidant enzyme system of the fetal lung have chronologically similar developmental patterns and both can be accelerated by the administration of exogenous glucocorticoids. To test whether the antioxidant enzyme system, like the surfactant system, is regulated, at least in part, by endogenous glucocorticoids, we injected pregnant rats for 3 days prior to delivery with metyrapone, an adrenal 11-beta hydroxylase inhibitor which crosses the placenta and blocks endogenous glucocorticoid synthesis, or saline. Metyrapone offspring had significantly decreased lung tissue disaturated phosphatidylcholine/total phospholipids (p less than 0.05) compared to controls at days 21 and 22 of gestation. Activities of the antioxidant enzymes superoxide dismutase, catalase, and glutathione peroxidase were similarly significantly reduced (p less than 0.01) in the lungs of metyrapone offspring at both gestational days studied. One day premature metyrapone pups demonstrated poorer survival than control pups from 25 min after delivery (44% survival versus 83%, p less than 0.05) to 90 min (6% survival versus 78%, p less than 0.01). These findings of delayed maturation of the surfactant and antioxidant enzyme systems following adrenal glucocorticoid blockade suggest that both systems are regulated, at least in part, by an endogenous glucocorticoid mechanism.

Animals↗
PubMed1985

Intrauterine growth-retarded rat pups show increased susceptibility to pulmonary O2 toxicity.

We used a nutritional deprivation model to produce intrauterine growth-retarded (IGR) rat pups (birth weight = approximately 75% of normal). The IGR newborns evidenced a marked reduction in tolerance to greater than 95% O2 exposure: 10-day survival = 10/47 (21%) versus 18/36 (50%) for control pups, and LT50 = 7.2 days versus 10 days for controls (p less than 0.01). Various lung parameters at birth and during O2 exposure were examined to try to define why prenatal undernutrition should compromise the survival of IGR rats in hyperoxia. We found decreased lung glutathione peroxidase and glucose-6-phosphate dehydrogenase activity (with normal superoxide dismutase and catalase levels) in the IGRs at birth; decreased lung disaturated phosphatidylcholine content (even more markedly decreased in 1-day premature pups); and decreased lung surface area/body weight. These factors and other features of newborn IGRs reported in the literature may help to explain how prenatal undernutrition compromises postnatal tolerance to prolonged high-O2 exposure.

Animals↗