Jay D. Mabrey

Isolation and Characterization of Polyethylene Wear Debris Associated with Osteolysis Following Total Shoulder Arthroplasty

We evaluated the interface membranes surrounding three total shoulder prostheses that had been removed because of progressive aseptic loosening associated with osteolysis. The mean time between the uncomplicated initial arthroplasty and the revision procedure was twelve years (10.5, 10.5, and 16.0 years). Membranes from around both the humeral and the glenoid component were obtained from all three shoulders and were studied histologically to determine the biological response involved in the development of aseptic loosening. For the purpose of comparison, periprosthetic tissue was also obtained from the sites of four failed total hip prostheses that were associated with osteolysis. Polyethylene particles were retrieved with an enzymatic digestion technique that involved the use of papain. Raman vibrational spectroscopy verified that the particles were ultra-high molecular weight polyethylene. The particles were isolated from the tissue, and a computerized image-analysis system characterized 582 of them in terms of size and morphology. Each particle was defined with the use of six shape descriptors: equivalent circle diameter, roundness, form factor, aspect ratio, elongation, and outline fractal dimension. The particles from the hips had a mean equivalent circle diameter (and standard error of the mean) of 0.62 +/- 0.03 micrometer, were predominantly globular in shape, and had low mean values for aspect ratio (1.46 +/- 0.02) and elongation (1.85 +/- 0.03) and relatively high values for roundness (0.74 +/- 0.01) and form factor (0.87 +/- 0.01). In contrast, the particles from the shoulders had a mean equivalent circle diameter of 1.04 +/- 0.03 micrometers. In addition, they had relatively high values for aspect ratio (2.36 +/- 0.07) and elongation (4.96 +/- 0.23) and correspondingly low values for roundness (0.54 +/- 0.01) and form factor (0.67 +/- 0.01), indicating that they were more fibrillar in shape. The particles from the shoulders and those from the hips were significantly different (p < 0.0001) with respect to all of the descriptors except outline fractal dimension. The particles from the shoulders, in general, were larger and more fibrillar than the particles from the hips.

Clinical pathway management of total knee arthroplasty

Using a retrospective cohort study design, the authors examined complications, readmissions, morbidity and mortality, and function scores in two groups of patients attended by the same surgeon for the year before and the year after the implementation of an outcomes management program with clinical pathways for patients undergoing total knee arthroplasty at an academic health center. The effectiveness of the pathway constantly was adjusted using variance analysis and continuous quality improvement techniques. This program reduced the length of stay by 57% from a premanagement value of 10.9 +/- 5.4 days in 1994 (Group 1) to 4.7 +/- 1.4 days in 1996 (Group 2). Hospital costs (based on an inflation adjusted cost to charge ratio) for all total knees were reduced 11% from

The effect of ultra-high molecular weight polyethylene wear debris on MG63 osteosarcoma cells in vitro.

13,328 +/-

Use of a supracondylar nail for treatment of a supracondylar fracture of the femur following total knee arthroplasty

3905 in 1994 to

Outcomes assessment of total hip and total knee arthroplasty: critical pathways, variance analysis, and continuous quality improvement.

11,862 +/-

Comparison of UHMWPE particles in synovial fluid and tissues from failed THA

4763 in 1996. Preoperative and postoperative knee scores were 41.1 +/- 16.3 and 84.2 +/- 16.0 for Group 1 and 42.5 +/- 13.0 and 87.0 +/- 10.4 for Group 2, respectively. There was no statistically significant difference between the preoperative or the postoperative knee scores of Groups 1 and 2. The application of clinical pathways, variance analysis, and continuous quality improvement toward the treatment of patients who had total knee arthroplasty at an academic health center resulted in significant savings in length of stay without adversely affecting overall outcome.

Survey of patient-oriented total hip replacement information on the World Wide Web.

BACKGROUND Focal osteolysis due to ultra-high molecular weight polyethylene wear debris involves effects on both bone resorption and bone formation. METHODS The response of MG63 osteoblast-like osteosarcoma cells to ultra-high molecular weight polyethylene wear debris isolated by enzymatic digestion of granulomatous tissue obtained from the sites of failed total hip arthroplasties was examined. Scanning electron microscopy, particle-size analysis, and Fourier transform infrared spectroscopy were used to characterize the number, morphology, size distribution, and chemical composition of the particles. Cell response was assessed by adding particles at varying dilutions to confluent cultures and measuring changes in cell proliferation (number of cells and [3H]-thymidine incorporation), osteoblast function (alkaline-phosphatase-specific activity and osteocalcin production), matrix production (collagen production and proteoglycan sulfation), and local cytokine production (prostaglandin-E2 production). RESULTS The mean size of the particles was 0.60 micrometer, and 95 percent of the particles had a size of less than 1.5 micrometers. The number of particles per gram of tissue ranged from 1.39 to 3.38x10(9). Three of the four batches of particles were endotoxin-free. Exposure of the cells to particles of wear debris significantly increased the number of cells (p<0.05) and the [3H]-thymidine incorporation (p<0.05) in a dose-dependent manner. In contrast, the addition of particles decreased alkaline-phosphatase-specific activity and osteocalcin production. Collagen production and proteoglycan sulfation were also decreased, while prostaglandin-E2 synthesis was increased by the addition of particles. CONCLUSIONS Ultra-high molecular weight polyethylene particles isolated from human tissue stimulated osteoblast proliferation and prostaglandin-E2 production and inhibited cell differentiation and matrix production. These results indicate that particles of wear debris inhibit cell functions associated with bone formation and that osteoblasts may produce factors in response to wear debris that influence neighboring cells, such as osteoclasts and macrophages. CLINICAL RELEVANCE Particles of wear debris, especially ultra-high molecular weight polyethylene, have been implicated in the loosening of implants and the development of osteolysis. The present study shows that particles of ultra-high molecular weight polyethylene isolated from human tissue inhibit osteoblast functions associated with bone formation. In addition, particles of wear debris induced osteoblasts to secrete factors capable of influencing neighboring cells, such as osteoclasts and macrophages. These results suggest that osteoblasts may play a role in the cascade of events leading to granuloma formation, osteolysis, and failure of orthopaedic implants.

SYMPOSIUM: The Emerging Impact of the Information Age on Orthopaedic Surgery*: Development of a Virtual Reality Arthroscopic Knee Simulator

Treatment of displaced or comminuted supracondylar fractures of the femur following total knee arthroplasty is challenging and problematic. Closed treatment has been associated with malunion, nonunion, and loss of motion, whereas early operative treatment has been associated with infection as well as nonunion. Intramedullary fixation of these fractures has the theoretical advantage of preserving periosteal blood supply while allowing early motion. The use of a nail specifically designed for supracondylar femur fractures to treat a a periprosthetic fracture about a well-fixed total knee arthroplasty is reported. This device provides a valuable treatment option to the surgeon treating this difficult problem.

Morphology of in vitro generated ultrahigh molecular weight polyethylene wear particles as a function of contact conditions and material parameters.

Using critical pathways, with variance analysis and continuous quality improvement techniques to refine the pathways, the efficiency of total hip and total knee surgeries in one academic health center was maximized. Using a retrospective cohort study design, complications, readmissions, morbidity/mortality, and function scores were examined in two groups of patients attended by the same surgeon for the year before and the year after the implementation of an outcomes management program. The length of stay was reduced by 57% for knee patients and by 46% for hip patients. Hospital costs were reduced 11% for all knees and 38% for hips. Complications were also significantly reduced. There was no statistically significant difference between pre- or postoperative knee or hip outcome scores. The program resulted in significant savings without adversely affecting overall outcome.

Setscrew Distal Locking for Intramedullary Nails: A Biomechanical Study

The size and morphology of ultra high molecular weight polyethylene (UHMWPE) wear particles isolated from synovial fluid and periprosthetic tissues from three failed total hip arthroplasties were evaluated. Hip capsule, femoral canal tissue, and synovial fluid were collected at the time of revision surgery. The polyethylene wear particles were isolated and then imaged using a scanning electron microscope. The size and morphology of the particles were quantified using an image analysis protocol. Five shape descriptors were defined for each particle: equivalent circle diameter (ECD, a measure of size having units of length), aspect ratio (AR), elongation (E), roundness (R), and form factor (FF). The size and shape of the polyethylene particles differed depending on the source. Femoral tissue particles had the lowest equivalent circle diameter (0.697 +/- 0.009 mm), aspect ratio (1.577 +/- 0.016), and elongation (1.912 +/- 0.030), but the highest values for roundness (0.715 +/- 0.005) and form factor (0.874 +/- 0.003). Hip capsule particles had the highest equivalent circle diameter (0.914 +/- 0.019 mm), aspect ratio (1.764 +/- 0.025), and elongation (2.488 +/- 0.053), but the lowest values for roundness (0.642 +/- 0.006) and form factor (0.803 +/- 0.005). The size and shape descriptors for synovial fluid particles (equivalent circle diameter: 0.763 +/- 0.012 mm; aspect ratio: 1.700 +/- 0.029; elongation: 2.212 +/- 0.054; roundness: 0.681 +/- 0.006; and form factor: 0.841 +/- 0.004) were intermediate among the femoral tissue and hip capsule particles. These data suggest that larger particles may become lodged in the hip capsule, while smaller particles may migrate to more distant tissues and subsequently cause aseptic loosening and osteolysis.