Erin Boynton - Academia.edu (original) (raw)

Papers by Erin Boynton

Blood

The persistence of hematopoietic cells from human adult cancellous bone fragments implanted subcu... more The persistence of hematopoietic cells from human adult cancellous bone fragments implanted subcutaneously into CB-17 scid/scid mice was studied. Recipient mice received either no pretreatment (control group) or pretreatment with 3 Gy total-body irradiation and anti-asialo GM1 sera (ASGM1; pretreated group) before implantation. Pretreated severe combined immunodeficient (SCID) mice implanted with human bone were subsequently given ASGM1 every 7 days for the duration of the experiments. At 12 weeks postimplantation, flow cytometry of cells from pretreated and control animal tissues detected human CD45+ cells in the mouse spleen (mean, 7.8% and 3.4% positive cells, pretreated and control animals, respectively), bone marrow (BM; mean, 16.5% and 4.8% positive cells, respectively), and blood (mean, 5.5% and < 2% positive cells, respectively), and in the implanted human bone (73% and 8.9% positive cells, respectively). At 12 weeks, pretreated mice had human granulocyte-macrophage colon...

PURPOSE To determine accuracy of direct MR arthrography (MRA) of the shoulder in the assessment o... more PURPOSE To determine accuracy of direct MR arthrography (MRA) of the shoulder in the assessment of patients with recurrent signs or symptoms of instability following prior shoulder instability repair. METHOD AND MATERIALS 40 patients (32 males, 8 females, mean age 28) with signs and symptoms of recurrent instability post previous instability repair (24 patients 1 prior surgery, 16 patients ≥ 2 prior surgeries) who underwent direct MRA of the shoulder prior to repeat surgery were studied. The mean interval between most recent prior surgery and direct MRA was 4.3 years (range 6 months – 29 years). Direct MRA studies, imaged on a 1.5T system, were reviewed by two musculoskeletal radiologists using consensus agreement in a blinded fashion. MR assessment included evaluation of the labrum (overall, SLAP, Bankart), rotator cuff, biceps tendon, articular cartilage and presence or absence of a Hill-Sachs lesion. The mean interval between MR imaging and repeat surgery was 6 months (range 6 da...

PURPOSE Analyze temporal MRI changes of non surgically treated rotator cuff tears (RCTs) with cor... more PURPOSE Analyze temporal MRI changes of non surgically treated rotator cuff tears (RCTs) with correlation to clinical exam. METHOD AND MATERIALS 59 shoulders (33 F: 26 M; mean age 59) with RCTs on initial MRI, managed nonoperatively (physiotherapy & rehabilitation) were prospectively studied. All patients had followup MRI >6 months after the initial study (mean 20 mos) and were assessed for pain, ROM and strength by a single orthopedic surgeon at baseline and followup time-points. All MRIs were assessed in blinded fashion for; RCT location, dimensions, and type (full/partial thickness RCTs [FTT/PTT]); ACJ OA; acromial shape/spurs; and muscular atrophy. Interval RCT size progression/diminution (defined as change in any dimension >2mm) was correlated to age, gender, other MRI findings and clinical findings. RESULTS Baseline MRI showed 29 FTTs, 26 PTTs and 4 combined FTT/PTTs. 58/59 RCTs involved supraspinatus, 10/59 involved multiple tendons. Followup MRI showed RCT progression ...

Canadian journal of surgery. Journal canadien de chirurgie, 2000

Aseptic loosening after total joint replacement remains the most common reason for long-term impl... more Aseptic loosening after total joint replacement remains the most common reason for long-term implant failure. Macrophages activated by submicron wear particles of the polyethylene liner used in joint replacement have been shown to be the source of periprosthetic bone loss. Understanding the role of material chemistry in macrophage activation and the subsequent effects that macrophage-derived enzymes play in the degradation of implanted biomaterials is key to developing methods for prolonging the lifespan of implantable materials.

The Journal of rheumatology, 1998

To investigate the role of T lymphocytes in ultra-high molecular weight polyethylene (UHMWPE) ind... more To investigate the role of T lymphocytes in ultra-high molecular weight polyethylene (UHMWPE) induced inflammation in joint arthroplasty. We address the role of T cells in wear induced inflammation by injecting the knee joints of both immune competent rats and mice and severe combined immunodeficient (SCID) mice with UHMWPE. Histological and immunohistochemical analysis of the synovial tissues was compared. Interaction between human T cells and UHMWPE particles was examined in vitro using T cell activation assays. Histological and immunohistochemical analysis of the knees of the immune competent animals showed significant UHMWPE induced inflammation. In contrast, the tissue in the SCID mice knee joints showed very little inflammatory response to UHMWPE despite phagocytosis of the particulate. Since the SCID mice have no functional T or B lymphocytes, it is highly likely that the lack of inflammation in knee joints may be due to the absence of mouse T cells, as the infiltration of T ...

Canadian journal of surgery. Journal canadien de chirurgie, 1995

To identify the cell types and patterns of cell distribution associated with particulate wear deb... more To identify the cell types and patterns of cell distribution associated with particulate wear debris in the membranes of patients who undergo revision of hip arthroplasty. Case series. Three university-affiliated hospitals. Twenty-nine patients who underwent revision of a hip arthroplasty for reasons other than infection. Eight patients were excluded because loosening of the prosthesis was found to be associated with infection, leaving 21 patients, 18 with aseptic loosening and 3 with recurrent dislocation. Retrieval of inflammatory membranes from loosened total hip prostheses. Results of aerobic and anaerobic tissue cultures, number of macrophages, T cells and B cells, and presence and histologic pattern of particulate debris in the membranes. None of the tissue cultures grew any organisms. All membranes contained T cells and macrophages, but B cells were present in only three patients at a low level. Particulate debris, surrounded by macrophages and foreign-body giant cells, was p...

The Journal of bone and joint surgery. American volume, 1988

Twenty-four patients who had degenerative arthritis of the lateral compartment of the knee that w... more Twenty-four patients who had degenerative arthritis of the lateral compartment of the knee that was associated with a valgus deformity and a superolateral tilt of the joint line were treated by distal femoral varus osteotomy. A surgical technique that was designed to produce a horizontal joint line and a tibiofemoral angle of zero degrees is described. At an average length of follow-up of four years, twenty-two of twenty-four patients had a successful result as judged by our protocol for evaluation. One osteotomy had to be revised for failure of fixation, and one patient had a pulmonary embolism that had a satisfactory outcome after the administration of anticoagulants. One patient required manipulation of the knee at six months. The simple surgical technique that we used was effective in realigning the femoral with the tibial axis in patients who had a valgus deformity of the knee, a superolateral tilt of the joint line, and osteoarthritis of the lateral compartment.

Canadian journal of surgery. Journal canadien de chirurgie, 1991

Radiologic and routine histologic examinations, transmission electron microscopy and scanning ele... more Radiologic and routine histologic examinations, transmission electron microscopy and scanning electron microscopy were carried out on membranes retrieved from the following hip implant prostheses: loose cemented metal-on-polyethylene, resorptive cysts around fixed cemented metal-on-polyethylene, cemented without polyethylene (Thompson), noncemented without polyethylene (Moore), loose ceramic-on-ceramic and loose noncemented metal-on-polyethylene. From histologic analysis the most common factor in the membranes reviewed, in terms of production of multinucleated giant cells, is the presence of polyethylene wear debris. Neither loosening of the implant nor the presence or absence of bone cement produces such cells within the membrane.

Skeletal Radiology, 2007

Posterior or lateral dislocation of the long head of biceps is a rare complication of shoulder di... more Posterior or lateral dislocation of the long head of biceps is a rare complication of shoulder dislocation that can result in inability to relocate the humerus. The diagnosis should be suspected when certain radiographic features are present at the initial presentation. Other imaging modalities can aid diagnosis when clinical management is unsuccessful or protracted. We present a case of surgically proven posterior dislocation of the biceps tendon with conventional radiographic, computed tomography and magnetic resonance imaging assessment. The literature on this subject is reviewed, and imaging features associated with the diagnosis are described.

Radiology, 2007

To retrospectively determine the accuracy of direct magnetic resonance (MR) arthrography of the s... more To retrospectively determine the accuracy of direct magnetic resonance (MR) arthrography of the shoulder in patients with recurrent or residual signs and/or symptoms of instability after prior instability repair, with surgical findings as the reference standard. After institutional ethics review board approval was obtained and informed consent was waived, 40 patients (31 men, eight women; mean age, 28 years) with recurrent instability after previous instability repair who underwent direct shoulder MR arthrography before repeat surgery were studied. Two musculoskeletal radiologists reviewed direct MR arthrographic studies by using consensus agreement in a blinded fashion. MR assessment included evaluation of the labrum (overall, superior, anterior and anteroinferior, posterior and posteroinferior), rotator cuff, biceps tendon, articular cartilage, and presence or absence of a Hill-Sachs lesion. Mean interval between MR arthrography and repeat surgery was 6.2 months (range, 6 days to 36 months). Surgical reports were compared with MR arthrographic results, and accuracy, sensitivity, and specificity of direct MR arthrography were determined. Accuracy, sensitivity, and specificity, respectively, of direct MR arthrography in diagnosis of overall labral tears (n = 26) were 91.9%, 96.2%, and 81.8%; those of superior labral tears (n = 16) were 89.2%, 93.8%, and 85.7%; and those of anteroinferior tears (n = 17) were 91.9%, 100%, and 85%. Overall accuracy for detecting rotator cuff injury (n = 17) was 87.2% (sensitivity, 94.1%; specificity, 81.8%); accuracy for biceps injury (n = 7) was 95.7% (sensitivity, 85.7%; specificity, 100%); accuracy for glenoid and/or humeral articular cartilage abnormality (n = 15) was 76.2% (sensitivity, 73.3%; specificity, 83.3%); and accuracy for Hill-Sachs lesion (n = 14) was 93.3%. Direct MR arthrography is accurate (91.9%) for assessing labral pathologic conditions and other internal derangements of the shoulder in patients with recurrent or residual signs and/or symptoms after prior shoulder instability repair.

Radiology, 2005

To investigate the temporal prevalence of a rim of increased signal intensity in the subcortical ... more To investigate the temporal prevalence of a rim of increased signal intensity in the subcortical part of the patella at T2-weighted magnetic resonance (MR) imaging after arthroscopic knee surgery or knee injury. The prospective and retrospective components of the study were performed after receiving approval from the institutional research ethics board. Written informed consent was obtained for the prospective component of the study. The need for informed consent was waived for the retrospective component of the study. The authors performed a prospective evaluation of serial MR images of the knee of four patients (three men and one woman; age range, 28-53 years; mean age, 36.8 years) after arthroscopic anterior cruciate ligament (ACL) reconstruction. They also performed a retrospective review of MR images of the knee from 90 consecutive patients (59 male and 31 female patients; age range, 13-66 years; mean age, 34.6 years) referred for the evaluation of an ACL injury. All imaging studies were evaluated in consensus by two musculoskeletal radiologists for the presence of a rim of increased signal intensity in the subcortical part of the patella at T2-weighted imaging. The presence of this signal intensity pattern was correlated with the time to imaging from surgery or joint injury. Logistic regression modeling was performed with increased subcortical signal intensity as the outcome and a second-degree polynomial for elapsed time as the predictor. All four patients who underwent imaging prospectively after ACL surgery showed increased T2-weighted signal intensity in the subcortical part of the patella 12 weeks after surgery. None of the patients showed these signal intensity changes at 6 or 24 weeks. A subcortical rim of increased T2-weighted signal intensity was seen in the patella in 24 (27%) of the 90 consecutive patients who underwent imaging for the assessment of possible ACL injury. Significant independent differences were seen in the prevalence of increased T2-weighted signal intensity in the subcortical part of the patella when related to time between injury and MR imaging (P = .002), with an increase in prevalence as time since injury increased and a decrease in prevalence in patients who underwent MR imaging more than 20 weeks after injury (P = .013). Increased T2-weighted signal intensity in the subcortical part of the patella appears to be a subacute transient MR finding seen after knee surgery or injury.

Microscopy Research and Technique, 2002

The interaction of macrophages and ultra-high molecular weight polyethylene (PE) wear plays an im... more The interaction of macrophages and ultra-high molecular weight polyethylene (PE) wear plays an important role in perpetuating chronic inflammation at the bone implant interface, leading to peri-implant osteolysis and mechanical failure of the implant. A model to study the interaction of human mature macrophages with orthopaedic biomaterial wear has been previously developed. With the use of the model, in this study, the mature human monocyte-derived macrophages (MDMs) were observed with light, fluorescent, and scanning electron microscopy (SEM), as well as transmission electron microscopy (TEM). The cell viability was investigated using calcein and ethidium staining. Following exposure to PE particulate, the morphology of the human MDMs was heterogeneous: rounded, flattened, and elongated. There was no morphological evidence of cytotoxicity or apoptosis. The MDM viability was not influenced by phagocytosis of PE particulate in a negative fashion. In fact, more prolonged cell viability was observed in the human MDMs exposed to PE particulate when compared to controls.

Journal of Surgical Research, 1999

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The Journal of Hand Surgery, 1998

Degenerative arthritis of the trapeziometacarpal joint is commonly associated with ligament laxit... more Degenerative arthritis of the trapeziometacarpal joint is commonly associated with ligament laxity and joint subluxation. Specifically, key pinch in an affected joint often results in dorsoradial joint subluxation. This study examined the role the 4 ligaments of the trapeziometacarpal joint play in preventing dorsoradial subluxation. Six fresh-frozen cadaver hands were dissected of all soft tissue to expose the joint capsule and ligaments of the trapeziometacarpal joint. Serial random sectioning of the intermetacarpal ligament, anterior oblique ligament, palmar oblique ligament, and dorsoradial collateral ligament (RCL) was performed. Dorsoradial displacement of the metacarpal shaft in relation to the trapezium was measured using a linear variable dimension transformer. In all 6 specimens, sectioning of the RCL resulted in the greatest dorsoradial subluxation of the metacarpal. The mean displacement due to sectioning of the RCL was 1.4 mm, compared with 0.08 mm for the intermetacarpal ligament, 0.06 mm for the anterior oblique ligament, and 0.2 mm for the palmar oblique ligament. The importance of the RCL in preventing dorsoradial subluxation may have clinical significance. This study suggests that repairing or reconstructing the RCL during ligament reconstruction of the trapeziometacarpal joint should be considered.

The Journal of Bone and Joint Surgery (American), 2009

Rotator cuff tears are very common, but little is known about the outcome of nonoperative treatme... more Rotator cuff tears are very common, but little is known about the outcome of nonoperative treatment of symptomatic tears in terms of progression and the need for surgical intervention. Fifty-nine shoulders in fifty-four patients (thirty-three women and a mean age of 58.8 years) with rotator cuff tears on initial magnetic resonance imaging who had been managed nonoperatively were studied retrospectively. All had magnetic resonance imaging scans acquired six months or more after the initial study. The progression of the rotator cuff tears was associated with age, anatomical and associated parameters, follow-up time, and structural and other magnetic resonance imaging findings. Baseline magnetic resonance imaging scans demonstrated thirty-three full-thickness tears, twenty-six partial-thickness tears, and four combined full-thickness and partial-thickness tears. Fifty-eight of the fifty-nine tears involved the supraspinatus tendon, and ten involved multiple tendons. Progression in tear size occurred more often among the patients who were followed more than eighteen months (thirteen [48%] of twenty-seven shoulders) compared with those who were followed for less than eighteen months (six [19%] of thirty-two shoulders). Five tears (one partial-thickness tear) decreased in size. More than half (52%; seventeen) of the thirty-three full-thickness tears increased in size compared with 8% (two) of the twenty-six partial-thickness tears (p = 0.0005). Only 17% (six) of the thirty-five tears in patients who were sixty years old or less deteriorated compared with 54% (thirteen) of the twenty-four tears in patients who were more than sixty years old (p = 0.007). No shoulder in a patient with a partial-thickness tear demonstrated supraspinatus atrophy, whereas 24% of those with a full-thickness tear demonstrated atrophy (p = 0.007). The proportion with an increase in tear size was significantly larger for shoulders with fatty infiltration than for those without it (p = 0.0089). Factors that are associated with progression of a rotator cuff tear are an age of more than sixty years, a full-thickness tear, and fatty infiltration of the rotator cuff muscle(s). In the long-term follow-up of nonoperatively treated rotator cuff tears, magnetic resonance imaging can be used to monitor rotator cuff changes and guide patient management.

Journal of Biomedical Materials Research, 2002

Macrophages are the major cell type observed in the inflammatory membrane retrieved at implant re... more Macrophages are the major cell type observed in the inflammatory membrane retrieved at implant revision surgery. In this study, mature human monocyte-derived macrophages (MDM) were adapted to a previously established in vitro model to examine the influence of high-density polyethylene (HDPE) particulate (4-10 microm) on MDM viability. HDPE particles were suspended in soluble type I collagen, which subsequently was solidified on glass coverslips. Mature human macrophages, derived from differentiating peripheral blood monocytes on polystyrene for 10 days, were incubated in culture media on collagen controls and collagen-particle substrata for 31 days. Histologic analysis demonstrated that MDMs were in contact with the particles at 2 h. The majority of the particles were associated with the cells within 24 h. Based on electron microscopy, those cells associated with the particles appeared to be morphologically activated rather than necrotic or apoptotic. Assessment of cell viability revealed no differences among the groups at 24 h, but at 31 days significantly more viable cells and higher DNA values were found associated with the particle groups versus the collagen controls. The histologic results validate human mature MDMs as a clinically relevant cell type for study of the role of polyethylene particulate in aseptic loosening. The cell viability results indicate that phagocytosis of HDPE is not toxic to MDMs but in fact prolongs MDM survival. The long-lived MDMs may play a role in perpetuating chronic inflammation surrounding implants.

Journal of Biomedical Materials Research, 1998

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Journal of Biomedical Materials Research, 2000

Osteolysis remains the most important problem in orthopedic implant failure. Wear debris from the... more Osteolysis remains the most important problem in orthopedic implant failure. Wear debris from the implant contains polyethylene (PE) particulate which has been shown to activate monocyte-derived macrophages (MDM). Although the response of MDM has been shown to be influenced by the size, shape, and chemical type of PE, the effect of chemically altered PE on MDM has not been studied. In this study, human MDM were seeded onto glass coverslips coated with virgin high density (HD)PE and chemically modified HDPE (impregnated with ppm levels of CoCl 2 and oxidized by heat) mixed with type I collagen and cultured for 96 h. Light microscopic evaluation demonstrated consistent phagocytosis of the HDPE particulate that was confirmed by scanning electron and transmission electron microscopy with little evidence of cytotoxicity. Evaluation of pro-inflammatory mediator secretion by MDMs in response to the virgin and chemically modified HDPE revealed significant differences in interleukin (IL)-1, tumor ne-crosis factor (TNF)-␣, and IL-6 secretion. A significant elevation of IL-1 secretion was observed after initial exposure to virgin HDPE particles compared with controls (p = 0.001). IL-1 secretion was also elevated in the low oxidized particle groups (p = 0.001), whereas the highly oxidized particles were not different than controls. Secretion of both IL-6 (p = 0.03) and TNF-␣ (p = 0.007) were significantly elevated by the low oxidized HDPE particles whereas the virgin and highly oxidized groups showed no difference. The different effects on MDM activation when HDPE surface chemistry was altered, highlight the importance of defining the particle properties when studying the role of MDM activation in in vitro systems and extrapolating these observations to the in vivo situation.

Journal of Biomedical Materials Research Part A, 2005

Controversy remains regarding the ability of silicone materials to induce a specific immune react... more Controversy remains regarding the ability of silicone materials to induce a specific immune reaction versus a nonspecific inflammatory response. Histopathological analysis of the tissue around failed breast implants reveals chronic inflammation with silicone gel droplets either surrounded by giant cells or engulfed by macrophages, areas of fibrosis, and necrosis. Macrophages are the key cells engulfing or forming foreign body giant cells. To address the mechanisms of silicone-induced inflammation a model of human monocyte-derived macrophages (MDMs) was developed. After sonication of silicone gel, the silicone droplets were embedded in Type I collagen and used to coat glass coverslips; human MDMs were subsequently seeded on the coverslips and maintained in culture for up to 7 days. The advantage of the model was that human macrophages could be studied histologically, and cytochemically as they interacted with well-characterized silicone materials. Initial analysis of the human macrophages shows phagocytosis of the silicone gel within hours of exposure to the material. Analysis for pro-inflammatory cytokines reveals significant transient secretion of IL-1 (p Ͻ 0.01) over controls by human macrophages upon exposure to silicone gel at 24 h.

Critical Reviews in Biotechnology, 1996

Page 1. Critical Reviews in Biotechnology, 16( 1):95-118 (1996) The Use of SCID Mice in Biotechno... more Page 1. Critical Reviews in Biotechnology, 16( 1):95-118 (1996) The Use of SCID Mice in Biotechnology and as a Model for Human Disease JS Sandhu, t2* E. Boynton, I R. Gorczynski, I and N. Hozumiz &#x27;Department of Surgery ...