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Biomedical subjects

G Bentley

Publications and source records attributed to G Bentley.

At least 37 records · Page 2Linked to original sources
PubMed2001

The treatment of scoliosis in muscular dystrophy using modified Luque and Harrington-Luque instrumentation.

We have treated 101 patients with scoliosis secondary to muscular dystrophy over a 13-year period; 64 had Duchenne's muscular dystrophy, 33 spinal muscular atrophy and four congenital muscular dystrophy. The patients underwent a modified Luque (87) or Harrington-Luque instrumentation (14) combined with a limited Moe fusion in all except 27 cases. A mean of 13 levels was instrumented. The mean preoperative sitting Cobb angle was 84 degrees (10 to 150) and the mean postoperative angle 40 degrees (52% correction). Most patients (96%) were able to discard their braces and there was a high level of patient satisfaction (89.6%). Less correction was seen for severe curves, and there was a greater recurrence of postoperative pelvic tilt in those patients not instrumented to the sacrum. Although the incidence of minor or temporary complications was high, these occurred chiefly in the early high-risk patients with very severe curves and considerable pre-existing immobility.

Adolescent↗
PubMed2001

Ewing sarcoma vs lymphoblastic lymphoma. A comparative immunohistochemical study.

To develop a practical immunohistochemistry panel for distinguishing lymphoblastic lymphoma from Ewing sarcoma (ES), we evaluated 17 ES and 27 lymphoblastic lymphoma and leukemia cases with antibodies to CD99, terminal deoxynucleotidyl transferase (TdT), leukocyte common antigen (LCA), CD43, CD79a, CD20, CD3, vimentin, and neuron-specific enolase (NSE). Three cases were bone lymphomas, 2 initially misdiagnosed as ES. All cases were CD99+. All lymphomas and leukemias were TdT+ compared to none of the ESs. None of the ESs expressed other lymphocytic markers, which were inconsistently expressed in the lymphomas and leukemias: CD43, 33%; LCA, 30%; CD79a, 19%; CD3, 19%; and CD20, 7%. Of the ESs, 88% were vimentin positive compared with 23% of lymphomas and leukemias. Vimentin was stronger and more diffuse in ES. NSE did not reliably stain any cases. When faced with the differential diagnosis of ES vs lymphoblastic lymphoma, an immunohistochemical panel that includes antibodies to CD99 and TdT is useful. Both epitopes are well preserved in fixed and decalcified tissue. A panel composed of antibodies to CD99 and TdT, in conjunction with other lymphocytic markers and vimentin, is highly sensitive and specific.

12E7 Antigen↗
PubMed2000

Staple vs. subcuticular vicryl skin closure in knee replacement surgery: a spectrophotographic assessment of wound characteristics.

Staple closure is a popular method of skin closure for patients undergoing knee replacement surgery. There are no guidelines regarding spacing of staples and some concern exists with regard to wound oxygenation in knees subject to early movement. We compared cutaneous wound characteristics in terms of blood oxygenation and blood content, using two types of skin closure. Staples or 4/0 subcuticular vicryl were used. We found favourable blood perfusion characteristics when using stapled closure. Our results also suggest that optimum wound oxygenation requires staple spacing of 6 mm or more.

Journal Article↗
PubMed2000

Total knee arthroplasty after high tibial osteotomy: a medium-term review.

A total of 50 consecutive knee arthroplasties in 42 patients who had undergone previous high tibial osteotomies have been reviewed with a minimum follow-up of 5 years and compared with 50 age-matched and sex-matched primary total knee arthroplasties. There were no significant preoperative differences between the 2 groups. Surgery in the osteotomy group took on average 23 minutes longer (P < .02), and there was a decrease of 80 flexion postoperatively but without an associated difference in knee scores. Patellar subluxation was also seen more frequently (P < .05). There was no difference in the revision rate at an average follow-up of > 6.2 years. Although there are significant technical difficulties and subtle clinical differences, the overall outcome remains good to excellent in most cases.

Aged↗
PubMed2000

Stability and bone preservation in custom designed revision hip stems.

Three types of uncemented femoral stems were designed for patients having revision hip surgery, with the goals of promoting axial stability and preserving proximal bone stock. These stems were made individually using computer design and manufacturing technology. Various design features were examined using nonlinear finite element analysis. All stems had lateral, medial, and anterior flares in the proximal region, proximal hydroxyapatite coating, and a collar. Based on a published classification system, the three designs were found suitable for variously encountered cavitary defects. For cases involving small amounts of bone destruction, a primary type of stem was used. With severe cases, an extended polished stem was used. For the worst cases, an extended stem with longitudinal cutting flutes and complete hydroxyapatite coating was necessary. The axial migration was measured radiographically for a 2-year period. The migration rates were comparable with those seen in cemented primary and in custom primary hydroxyapatite coated stems. Dual energy x-ray absorptiometry data were obtained during a 4-year postoperative period. Average bone density in all regions was maintained within 12% of the immediate postoperative values. It was concluded that the proposed system for treating patients needing revision hip surgery showed desirable properties that were comparable to primary hip replacements.

Bone Density↗
PubMed2000

Modulation of the formation of adhesions during the healing of injured tendons.

The formation of restrictive adhesions around the musculotendinous unit after injury is one of the most vexing processes faced by the surgeon. In flexor tendons it has been shown that the synovial tissue is the source of aggressive fibroblasts which contribute to this process. Using a rabbit model, we have examined the effects of treating the synovial sheath with the antimetabolite 5-fluorouracil (5-FU) for five minutes. Inflammatory, proliferative and molecular markers were compared in the response of the treated and control tendons to injury. Compared with a control group we found that the proliferative and inflammatory responses were significantly reduced (p < 0.001) in the treated tendons. Not only was there a reduction in the cellular and cytokine response, but there also was a significant (p < 0.001) reduction in the level of activity of the known pro-scarring agent, transforming growth factor beta 1 (TGF-beta1). These pilot studies indicate that the formation of restrictive adhesions may be modulated using a simple single-touch technique in the hope of producing a better return of function.

Animals↗
PubMed2000

Significance of the Gleason scoring system after neoadjuvant hormonal therapy.

Neoadjuvant hormonal therapy (NHT) induces morphologic changes in prostate adenocarcinoma that result in the assignment of higher Gleason scores on average than in pretreatment biopsy specimens. This outcome has led to the recommendation that the Gleason scoring system not be applied to prostate adenocarcinoma specimens after NHT. We reviewed the radical prostatectomy specimens of 116 patients who had received NHT. Gleason scores were assigned on the post-treatment specimens by applying the usual criteria; in addition, an estimated pretreatment Gleason score was assigned on the basis of knowledge of the morphologic alterations associated with NHT. Finally, an estimate of the degree of therapy effect was assigned: little or no evidence of hormonal effect (grade 1) to marked therapy-related changes (grade 3). Both the post-treatment and the estimated pretreatment Gleason score correlated significantly with biochemical progression (P = 0.03 and P = 0.03, respectively; log-rank test). The degree of therapy effect did not correlate with progression (P = 0.46; log-rank test). This limited analysis suggests that despite the morphologic alterations induced by NHT, post-treatment Gleason score remains a significant prognostic measure. Further studies in more uniformly treated populations are required to confirm this observation.

Adenocarcinoma↗
PubMed1999

Design and application of combined hip-knee intramedullary joint replacements.

Cases in which there is a total hip arthroplasty and a stemmed total knee arthroplasty in the same femur, with loosening of 1 or both components, with serious endosteal bone loss or even a fracture between the stems present a difficult reconstruction problem. We describe a reconstruction using a combined hip and stemmed knee, designed so that they could be rigidly connected during the surgical procedure. The advantages of this implant design are that the entire femur with its muscle attachments is preserved, and the inherent stability allows for immediate weight bearing. To determine the viability of the connection between the hip and the knee, a stress analysis was carried out using finite element analysis. Guidelines were thus provided for the required metal and cement thicknesses. Three case examples are presented with an average follow-up of 3 years. It was shown that the combined hip-knee implant could provide successful results for these difficult reconstructive problems in appropriately selected cases.

Adult↗
PubMed1999

Blood loss in Duchenne muscular dystrophy: vascular smooth muscle dysfunction?

Patients with Duchenne muscular dystrophy (DMD) tend to bleed more during surgery than do patients with other conditions. A retrospective analysis of blood loss after spinal surgery for scoliosis was therefore undertaken in 102 patients undergoing surgery in the senior author's unit. These included 48 patients with DMD, 26 patients with spinal muscular atrophy, and a miscellaneous group of 28 other patients most of whom had idiopathic scoliosis. For each patient the age at surgery, estimated blood volume, duration of operation, Cobb angle, and number of vertebrae fused were recorded and compared. Expression of dystrophin in skeletal muscle and the underlying gene mutation were also determined. The estimated blood loss in patients with DMD was significantly higher than that in patients with spinal muscular atrophy undergoing the same or similar procedure (P < 0.005) and was also significantly greater than that of the third group, which consisted mostly of patients with idiopathic scoliosis (P < 0.0005). Blood loss in the patient group with DMD showed a significant relationship with duration of surgery (P < 0.05). As most patients expressed no dystrophin, this did not correlate with the estimated blood loss. There was also no correlation between the estimated blood loss and the type of gene mutation found causing DMD. The authors' previous observations confirm the increased blood loss in patients with DMD who undergo scoliosis surgery. Because children with DMD lack dystrophin in all muscle types, including smooth muscle, the excessive blood loss may be because of a poor vascular smooth muscle vaso-constrictive response due to a lack of dystrophin.

Adolescent↗
PubMed1999

Mechanisms of internalization of Staphylococcus aureus by cultured human osteoblasts.

Staphylococcus aureus is an important bone pathogen, and evidence shows that this organism is internalized by chick osteoblasts. Here we report that S. aureus is internalized by human osteoblasts. Internalization was inhibited by monodansylcadaverine and cytochalasin D and to a lesser extent by ouabain, monensin, colchicine, and nocodazole. We propose that internalization occurs via a receptor-mediated pathway, requiring the participation of cytoskeletal elements, principally actin.

Actins↗
PubMed1999

The results at ten years of the Insall-Burstein II total knee replacement. Clinical, radiological and survivorship studies.

We reviewed the outcome of 146 Insall-Burstein II total knee replacements carried out in 121 patients over a period of nearly four years in a general orthopaedic unit. At a mean follow-up of ten years, 94 knees in 78 patients were available for review. Six patients (7 knees) were lost to follow-up and 37 (45 knees) had died. The clinical outcome using the scoring system of the Hospital for Special Surgery (HSS) was excellent or good in 79% of patients, fair in 14% and poor in 7%. The mean preoperative HSS score was 31, improving to 79 at the latest review. Using the newer rating system of the Knee Society, the mean score at ten years was 87 and the mean functional score 56. The arc of flexion improved from a mean preoperative value of 88 degrees to 100 degrees. The 18 patients who had had a previous high tibial osteotomy were analysed separately and were found to have benefited equally from the operation. Nine prostheses were revised, giving a cumulative survival rate of 92.3% at ten years. Radiological evaluation of 104 radiographs showed radiolucent lines around ten tibial components, none of which required revision. Anterior knee pain was a significant problem.

Aged↗
PubMed1998

Response of chondrocyte subpopulations cultured within unloaded and loaded agarose.

Although it is well known that the metabolism of chondrocytes can be altered by the application of mechanical strain, it is unclear whether chondrocytes from the superficial and deep zones of cartilage respond in a similar manner. In this study, chondrocytes from the uppermost 15-20% (superficial cells) and the remaining tissue (deep cells) from bovine articular cartilage were isolated separately and cultured in agarose constructs. Cell deformation on application of a 15% static compressive strain was identical for both subpopulations after 24 and 72 hours in culture. The constructs were incubated under static and dynamic (0.3, 1, and 3 Hz) strains of 15% amplitude. Glycosaminoglycan synthesis by deep cells was unaffected by static strain or 3 Hz dynamic strain, whereas 0.3 Hz produced a significant reduction and 1 Hz induced a highly significant 50% stimulation of glycosaminoglycan synthesis (p < 0.001). Superficial cells exhibited a general inhibition of glycosaminoglycan synthesis. By contrast, proliferation of superficial cells was stimulated by dynamic strain whereas deep cells were not influenced. It has been suggested previously that mechanotransduction-induced controls of glycosaminoglycan synthesis and proliferation in chondrocytes embedded in agarose are uncoupled. Data presented in this study demonstrate that the two processes do, in fact, occur in different subpopulations of chondrocytes within the full-depth cell isolate.

Animals↗
PubMed1998

Treatment of painful articular cartilage defects of the patella by carbon-fibre implants.

Between 1989 and 1993 we implanted a matrix support prosthesis made of carbon fibre for the treatment of chronic painful articular defects of the patella in 27 patients. The mean period of follow-up was 33 months (11 to 54) with clinical and arthroscopic evaluation of the implant. Overall, there were four excellent, three good, seven fair and 13 poor results. Nine patients subsequently had a patellectomy for persistent pain at a mean of 27 months after surgery (14 to 47). The mean visual analogue pain scores in those who retained their patella were 7.6 before operation and 5.5 at the time of the latest follow-up. Patient satisfaction for the entire group was 41%. There appeared to be good incorporation of the prosthesis and a satisfactory ingrowth of fibrocartilage, but the poor results in 48% and low patient satisfaction discourage us from recommending the procedure for lesions of the articular cartilage of the patella. The consistent seeding of the joint with carbon-fibre debris and a histiocytic giant-cell reaction in the synovium are also a cause for concern.

Adolescent↗
PubMed1998

Distal femoral osteotomy for lateral compartment osteoarthritis of the knee.

Twenty-one patients with lateral compartment osteoarthritis and valgus deformity of the knee underwent distal femoral supracondylar osteotomy (medial closing wedge) between 1983 and 1993 with follow-up ranging from 1 to 8 years. Ten knees had plaster cast immobilization, 5 had fixation with 2 staples supplemented with a plaster cast, and 6 knees had rigid internal fixation with an AO blade plate. Thirty-three percent of patients had a satisfactory result using the HSS score, and 57% had a satisfactory result using the Knee Society Clinical Rating. Fifty-seven percent had a significant complication, including severe knee stiffness requiring manipulation under anesthesia (48%), nonunion/delayed union (19%), infection (10%), and fixation failure (5%). Five (19%) knees required total knee replacement within 5 years of surgery. Satisfactory results were obtained only in those patients who had less severe degrees of osteoarthritis confined to the lateral compartment (grades I to III), adequate correction of valgus deformity (the anatomical axis within 2 degrees from zero), and rigid internal fixation to permit postoperative early mobilization. These results indicate that distal femoral osteotomy is a satisfactory procedure in the young, active patient with osteoarthritis of the lateral compartment of the knee, but requires precise surgical technique and rigid internal fixation.

Adult↗