Michael Tanzer - Academia.edu (original) (raw)

Papers by Michael Tanzer

The Journal of Arthroplasty, 2001

We prospectively assessed femoral bone remodeling using dual-energy x-ray absorptiometry for 2 ye... more We prospectively assessed femoral bone remodeling using dual-energy x-ray absorptiometry for 2 years after total hip arthroplasty. Thirty-nine hips were randomized to receive a titanium proximally porous-coated femoral component with or without hydroxyapatite-tricalcium phosphate coating. Although both stems resulted in alterations in the periprosthetic bone mineral density, the hydroxyapatite-tricalcium phosphate coated stems had significantly less femoral bone loss than the uncoated stems at 2-year follow-up. This reduced femoral bone loss may provide short-term and long-term advantages over noncoated stems.

Journal of Bone and Joint Surgery-british Volume, 2000

This second edition of the widely recognised reference text on the principles of spinal surgery h... more This second edition of the widely recognised reference text on the principles of spinal surgery has technical descriptions of each of the instrumentation systems available. In a rapidly evolving field such as this, many texts are soon outdated, but the clear and succinct approach of this book makes it a valuable edition to the library of the specialist spinal surgeon. The general section and that on regional considerations provide an excellent set of principles for instrumented spinal surgery. Although, inevitably, the descriptions of the surgical techniques and details of the instrumentation largely reflect the personal preferences of the author of the chapter, the basic principles are sound. These two sections alone make the book invaluable to practising spinal surgeons. The third section is a series of descriptions by either the inventors or the main proponents of specific implant systems for the spine. This text has an extended role over and above the instruction manuals provided by the manufacturers. For surgeons using these specific systems, each chapter is an excellent overview of the pattern of the principles of techniques; some provisional results are also provided. This is an excellent book for the spinal specialist, but would be of limited interest to the general orthopaedic surgeon.

McGill Journal of Medicine, 2020

It is estimated that osteoporosis is responsible for about 300 000 hip fractures per year in the ... more It is estimated that osteoporosis is responsible for about 300 000 hip fractures per year in the United States. Effective prevention of these fractures has been demonstrated using bisphosphonates. However, their mechanism of action has not been elucidated. Furthermore, the precise effect of bisphosphonates on the femoral neck and surrounding areas has never been studied. We are interested in establishing a protocol to analyze the bone quality of proximal femurs from patients treated with bisphosphonates. Following hip replacement surgery, the aim is to determine whether imaging and compression testing of cancellous bone from the discarded femoral necks can accurately assess the bone’s microarchitectural and biomechanical properties, respectively. To validate the technique, it was first tested on an untreated population. A bone biopsy trephine was used to extract cylindrical cores of trabecular bone from the centre of femoral necks. Densitometry, microcomputed tomography, and compres...

The Bone & Joint Journal, 2019

Aims The purpose of this study was to evaluate the biological fixation of a 3D printed porous imp... more Aims The purpose of this study was to evaluate the biological fixation of a 3D printed porous implant, with and without different hydroxyapatite (HA) coatings, in a canine model. Materials and Methods A canine transcortical model was used to evaluate the characteristics of bone ingrowth of Ti6Al4V cylindrical implants fabricated using laser rapid manufacturing (LRM). At four and 12 weeks post-implantation, we performed histological analysis and mechanical push-out testing on three groups of implants: a HA-free control (LRM), LRM with precipitated HA (LRM-PA), and LRM with plasma-sprayed HA (LRM-PSHA). Results Substantial bone ingrowth was observed in all LRM implants, with and without HA, at both time periods. Bone ingrowth increased from 42% to 52% at four weeks, to 60% to 65% at 12 weeks. Mechanical tests indicated a minimum shear fixation strength of 20 MPa to 24 MPa at four weeks, and 34 MPa to 40 MPa at 12 weeks. There was no significant difference in the amount of bone ingrowt...

Annals of Medicine and Surgery, 2020

Introduction: Orthopaedic surgery is characterized by surgical tasks that are physical, repetitiv... more Introduction: Orthopaedic surgery is characterized by surgical tasks that are physical, repetitive and require some degree of stamina from the surgeon. Occupational injuries are alarmingly common in orthopaedic surgery with two-thirds of all surgeons reporting a work-related musculoskeletal (MSK) injury during their career. One of the leading causes of the high level of MSK injuries among orthopaedic surgeon is lack of ergonomics of the operating room. Implementing an ergonomic process has been shown to be effective in reducing the risk of developing MSK disorders in other high-risk industries. We reviewed well-established and effective ergonomic guidelines from the industrial workplace and determined the pertinent principles that could be transferred to the operating room to help reduce the number and severity of common orthopaedic work-related MSK injuries. Methods: We reviewed the ergonomic guidelines, primarily from the Occupational Safety and Health Administration (OSHA), that specifically address minimizing the risk of these work-related injuries and that are transferable to the operating room. In addition, the ergonomic guidelines from the Canadian Center for Occupational Health and Safety (CCOHS), the National Institute for Occupational Safety and Health (NIOSH) and the Centers for Disease Control and Prevention (CDC) were reviewed. Results: Many of the guidelines to avoid work-related injuries in industry are transferable to the operating room. The pertinent guidelines clearly indicated how to adjust the height of the operating table, the proper design of hand and power tools and the modifications to the operating room environment that can help prevent injury. These guidelines from industry include maintaining a neutral posture and joint alignment, working with the appropriate hand tools and minimizing the lower extremity fatigue by using the proper footwear and floor mats. Discussion: Optimizing the occupational environment and utilizing well-established ergonomic principle from industry is both feasible and practical in the operating room to decrease the incidence of musculoskeletal injuries among this high-risk profession. These guidelines are simple, effective and are easy to implement by orthopaedic surgeons in order to minimize their risk of sustaining a work-related injury.

Clinical Orthopaedics and Related Research®, 2016

Clinical orthopaedics and related research, 2018

The implementation of care pathways in hip arthroplasty programs has been shown to result in a de... more The implementation of care pathways in hip arthroplasty programs has been shown to result in a decreased length of stay (LOS), but often multiple elements of a care pathway are implemented at the same time. As a result, it is difficult to understand the impact each of the individual modifications has made to the patient's prepathway care. In particular, it is unknown what the role of patient expectations pertaining to anticipated LOS alone is on the LOS after primary THA. (1) Does changing the patient's expectations regarding his or her anticipated LOS, without intentionally changing the rest of the care pathway, result in a change in the patient's LOS after primary THA? (2) Is the resultant LOS associated with the patient's age, gender, or day of the week the surgery was performed? We retrospectively compared the LOS in 100 consecutive patients undergoing THA immediately after the implementation of a 4-day care pathway (4-day Group) with 100 consecutive patients, 3 ...

The Clinical journal of pain, 2017

Perceptions of injustice have been associated with problematic recovery outcomes in individuals s... more Perceptions of injustice have been associated with problematic recovery outcomes in individuals suffering from a wide range of debilitating pain conditions. It has been suggested that, in patients with chronic pain, perceptions of injustice might arise in response to experiences characterized by illness-related pain severity, depressive symptoms, and disability. If symptoms severity and disability are important contributors to perceived injustice, it follows that interventions that yield reductions in symptom severity and disability should also contribute to reductions in perceptions of injustice. The present study examined the relative contributions of post-surgical reductions in pain severity, depressive symptoms and disability to the prediction of reductions in perceptions of injustice. The study sample consisted of 110 individuals (69 women and 41 men) with osteoarthritis of the knee scheduled for total knee arthroplasty (TKA). Patients completed measures of perceived injustice,...

Journal of Children's Orthopaedics, 2016

Introduction Forceful and repetitive maneuvers constitute the majority of pediatric orthopedic su... more Introduction Forceful and repetitive maneuvers constitute the majority of pediatric orthopedic surgical tasks, thus subjecting surgeons to the risk of musculoskeletal (MSK) injuries during their years in practice. The aim of this study was to assess the prevalence, characteristics and impact of MSK disorders among pediatric orthopedic surgeons. Methods A modified version of the physical discomfort survey was sent to surgeons who were members of the Pediatric Orthopedic Society of North America (POSNA) via e-mail. The collected data were analyzed using descriptive statistics, one-way analysis of variance, and Fisher's exact test. p values of <0.05 were considered statistically significant. Results Of the 402 respondents, 67 % reported that they had sustained a work-related MSK injury, of which the most common diagnoses were low back pain (28.6 %) and lateral elbow epicondylitis (15.4 %). Among those which reported an injury, 26 % required surgical treatment and 31 % needed tim...

The Journal of Arthroplasty, 2016

BMC musculoskeletal disorders, Jan 24, 2015

Intra-articular osteoid osteoma (OO) causes irreversible joint damage. Its treatment of choice is... more Intra-articular osteoid osteoma (OO) causes irreversible joint damage. Its treatment of choice is radiofrequency ablation (RFA); however, some areas of the acetabulum are hard to access. Therefore, hip arthroscopy was used to treat this tumor. We aim to systematically review the literature with regards to arthroscopic management of acetabular OO, and to report a further case in which hip arthroscopy was used for treatment. PubMed and EMBASE were searched for articles relevant to the arthroscopic management of acetabular OO on December 2, 2014. All articles published on and before that date were reviewed, and studies which met our pre-determined inclusion criteria were included. Articles screening and data abstraction were done by two reviewers independently. We also presented a 31-year-old man with acetabular OO who underwent hip arthroscopy for the management of his tumor after failing to respond to medications and computed tomography scan (CT)-guided RFA. The initial search reveal...

Canadian journal of surgery. Journal canadien de chirurgie, 2007

We documented the following components of waiting time for total hip replacement (THR): first sur... more We documented the following components of waiting time for total hip replacement (THR): first surgical consultation, date of decision to operate and date of surgery. We then explored whether these intervals differed by age, sex, occupation or quality-of-life score. We used a cross-sectional design and collected the primary data from patients 2 to 4 weeks before they underwent THR. Trained interviewers administered the Medical Outcomes Study Short Form-36 and the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), which included data on event dates, conservative treatment, demographic information and quality of life. We illustrated waiting times, quality of life and past use of conservative treatment (i.e., cane, exercise, physiotherapy) with descriptive statistics (mean [standard deviation] or median [intraquartile range]) for continuous variables and with percentages for categorical variables. We plotted KaplanMeier graphs for each waiting time component and emp...

Journal of musculoskeletal & neuronal interactions, 2000

To determine the influence of femoral hip prosthesis design and composition on regional periprost... more To determine the influence of femoral hip prosthesis design and composition on regional periprosthetic bone remodelling as a function of time in asymptomatic patients. Bone mineral density (BMD) changes surrounding two differently designed porous-coated femoral prostheses (S-ROM, n=111; and Multilocki, n=62) were determined serially over a 24 month interval. There was a subset of patients with Multilock implants that were coated with a 50 micron film of hydroxy-apatite (n=23) over the porous surface. Seven Gruen zones defined the periprosthetic bone regions (LUNAR ORTHO software). Inclusion criteria were primary implants, Harris hip scores >or=95 and no radiographic evidence of loosening. For the S-ROM femoral component, at 6 months all zones showed a significant decrease in BMD relative to the immediate postoperative baseline measurements; mean loss varied from 4.3% to 17.4%. At 24 months mineral change varied from -10.8% to +1% for Gruen zones 1 to 6. Gruen zone 7, the calcar, ...

$Research paper thumbnail of Classification of subcapital hip fractures$

Canadian journal of surgery. Journal canadien de chirurgie, 2002

Canadian journal of surgery. Journal canadien de chirurgie, 2001

To determine the effect of 5 different femoral components used in total knee arthroplasty (TKA) o... more To determine the effect of 5 different femoral components used in total knee arthroplasty (TKA) on the contact area and tracking characteristics of the nonresurfaced patella and to identify any design features that might adversely affect these characteristics. An in-vitro study. The biomechanics laboratory, Department of Mechanical Engineering, McGill University, Montreal. Six fresh-frozen cadaveric knee-joint specimens. An unconstrained quadriceps simulator was used to apply the conditions of static lifting to the specimens first in their normal state and then sequentially implanted with femoral and tibial components of various designs (Miller/Galante II, Anatomic Modular Knee [AMK] System, Whiteside Ortholoc Modular, press-fit condylar and Insall-Burstein II). Patellar 3-dimensional tracking characteristics, determined by using a 6 degrees-of-freedom electromechanical goniometer attached directly to the patella, and patellar contact pressure measurements, obtained using low-range ...

The Journal of Bone and Joint Surgery. British volume, 2005

The effect of zoledronic acid on bone ingrowth was examined in an animal model in which porous ta... more The effect of zoledronic acid on bone ingrowth was examined in an animal model in which porous tantalum implants were placed bilaterally within the ulnae of seven dogs. Zoledronic acid in saline was administered via a single post-operative intravenous injection at a dose of 0.1 mg/kg. The ulnae were harvested six weeks after surgery. Undecalcified transverse histological sections of the implant-bone interfaces were imaged with backscattered scanning electron microscopy and the percentage of available pore space that was filled with new bone was calculated. The mean extent of bone ingrowth was 6.6% for the control implants and 12.2% for the zoledronic acid-treated implants, an absolute difference of 5.6% (95% confidence interval, 1.2 to 10.1) and a relative difference of 85% which was statistically significant. Individual islands of new bone formation within the implant pores were similar in number in both groups but were 69% larger in the zoledronic acid-treated group. The bisphosph...

The Journal of Bone and Joint Surgery, 1999

W e studied retrospectively a consecutive series of 547 shoulders in 529 patients undergoing oper... more W e studied retrospectively a consecutive series of 547 shoulders in 529 patients undergoing operation for instability. In 41, the cause of instability was considered to be lateral avulsion of the capsule, including the inferior glenohumeral ligament, from the neck of the humerus, the HAGL lesion. In 35, the lesion was found at first exploration, whereas in six it was noted at revision of a previous failed procedure. In both groups, the patients were older on average than those with instability from other causes. Of the primary cases, in 33 (94.3%) the cause of the first dislocation was a violent injury; six (17.4%) had evidence of damage to the rotator cuff and/or the subscapularis. Only four (11.4%) had a Bankart lesion. In patients undergoing a primary operation in whom the cause of the first dislocation was a violent injury, who did not have a Bankart lesion and had no suggestion of multidirectional laxity, the incidence of HAGL was 39%.

Clinical Orthopaedics and Related Research, 1994

Modularity is being diversified in total hip prostheses to increase surgical latitude in optimizi... more Modularity is being diversified in total hip prostheses to increase surgical latitude in optimizing implant fixation and adjusting hip biomechanics. However, several problems have been clearly identified with implant modularity. First generation metal-backed acetabular components have shown deficiencies in the locking mechanism, the congruency and extent of polyethylene liner support, and polyethylene thickness, all of which have been implicated in accelerated polyethylene wear and failure. Evidence of screw motion against the metal backing, release of particulate material, and focal osteolysis have also been observed. At the head/neck junction evidence of corrosion and fretting has been documented with both similar-metal and mixed-metal taper combinations. Femoral prostheses with other sites of modularity present additional concerns with regard to mechanical integrity and generation of particulate debris by fretting. The modular junctions of three hip prostheses, the S-ROM, Infinity, and RMHS, were subjected to wet environment high cycle mechanical testing in a worst-case loading scenario. Preliminary results at relatively low loads up to three times body weight indicated gross stability of the modular junctions with evidence of minor fretting damage. Analysis of water solutions surrounding the modular junctions after ten to 20 million loading cycles yielded counts of one to three micron sized particles totalling several hundred thousand

Clinical Orthopaedics and Related Research®, 2011

Background The recent interest in hip resurfacing arthroplasty is motivated by its potential adva... more Background The recent interest in hip resurfacing arthroplasty is motivated by its potential advantages over THA. One advantage of hip resurfacing arthroplasty is that it conserves bone on the femoral side; however, it is unclear whether it does so on the acetabular side. Questions/purposes We determined whether the amount of acetabular reaming and acetabular bone removal required for hip resurfacing arthroplasty is equal to, less than, or greater than that for THA. Patients and Methods We prospectively evaluated the femoral neck size of 180 hips at the time of primary THA in an identical manner to when carrying out a hip resurfacing arthroplasty. Based on the femoral neck measurement, we determined the minimum cup size that would be used and reamer size required if the hip was undergoing a resurfacing. We compared this to the reamer size actually required to prepare the acetabulum for the THA cup. We calculated the difference between the predicted reaming size for resurfacing and the actual reaming size to determine the effect of resurfacing on acetabular bone stock. Results Overall, 71%, 57%, and 41% of THAs would have had extra acetabular bone removed to implant a hip resurfacing arthroplasty cup with a line-to-line (0-mm), 1-mm, or 2-mm press fit, respectively. Conclusions When compared to THA, hip resurfacing arthroplasty commonly results in additional acetabular bone resection.

Clinical Orthopaedics & Related Research, 2012

Background There has been considerable interest in minimally invasive surgical (MIS) THA in recen... more Background There has been considerable interest in minimally invasive surgical (MIS) THA in recent years. The MIS anterolateral approach, or the MIS Watson-Jones approach, is a novel intermuscular abductor-sparing technique. Early reports from case series suggest the potential for superior function and reduced complications; however, the available information from clinical reports is inadequate to suggest surgeons should change from their accepted standard approach. Questions/purposes We examined the potential superiority of this anterolateral approach, as judged by quality-oflife (QoL) measures, radiographic parameters, and complications, compared to limited-incision MIS direct lateral and MIS posterolateral approaches. Methods We performed a prospective randomized controlled trial involving five surgeons at three centers, recruiting 156 patients undergoing primary THA to receive either the MIS anterolateral or the surgeon's preferred approach (direct lateral or posterolateral). For the 135 patients we report, we collected patient-reported WOMAC, SF-36, Paper Adaptive Test in 5 Domains of Quality of Life in Arthritis Questionnaire [PAT5D], and patient satisfaction scores. We recorded complications and evaluated radiographs for prosthetic component position, subsidence, and fracture. Minimum followup was 24 months (mean, 30 months; range, 24-42 months). Results QoL and patient-reported satisfaction were similar between groups. Radiographic evaluation demonstrated no differences in acetabular component positioning; however, mean stem subsidence was 4.6 mm for the MIS anterolateral group and 4.1 mm for the alternate group, with differences observed among the three centers for stem subsidence and fracture. One center had increased rate of The institutions of the authors (NVG, SC, DSG, BAM, MT, AEG, CPD) have received funding from Zimmer, Inc (Warsaw, IN, USA). One or more of the authors (DSG, BAM, CPD) certify that each has received or may receive payments or benefits, during the study period, an amount in excess of $10,000, from Zimmer, Inc. The remaining authors certify that they have no commercial associations (eg, consultancies, stock ownership, equity interest, patent/licensing arrangements, etc) that might pose a conflict of interest in connection with the submitted article. All ICMJE Conflict of Interest Forms for authors and Clinical Orthopaedics and Related Research editors and board members are on file with the publication and can be viewed on request. Clinical Orthopaedics and Related Research neither advocates nor endorses the use of any treatment, drug, or device. Readers are encouraged to always seek additional information, including FDA approval status, of any drug or device before clinical use. Each author certifies that his or her institution approved the human protocol for this investigation, that all investigations were conducted in conformity with ethical principles of research, and that informed consent for participation in the study was obtained.