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Conventional joint motion simulators for pre-clinical testing of total knee arthroplasty (TKA) designs typically manipulate the knee in directed displacement, force, or simulated muscle control, however, a platform capable of employing all three control modes has not been previously described. We have developed muscle tensioning capabilities for an existing force/displacement-controlled joint motion simulator. This study’s purpose is to compare the kinematics of this muscle actuator system (MAS) to those recorded using an Oxford Knee Rig (OKR), which represents the gold-standard for gravity-dependent quadriceps-controlled knee flexion activities. In this work, the MAS is mounted on a VIVO joint motion simulator. The MAS simulates quadriceps muscle forces to extend a mechanical phantom knee. The VIVO applies flexion angle-dependent forces/torques, producing a gravity force acting from the centres of hip-to-ankle, with virtual lengths assumed to match the physical extended attachments to which the phantom mounts within an OKR. An optical tracking system measures tibiofemoral (TF) and patellofemoral (PF) kinematics and a loadcell measures the applied quadriceps force during gravity-dependent, quadriceps-controlled extension. The quadriceps is controlled using flexion-driven closed-loop control. Using both rigs, tests were conducted with nominal and ± 5 mm (alta/baja) patella heights. Nominal PF kinematics and quadriceps forces of the two rigs were compared. Due to differences in quadriceps force measurement conventions between the two rigs, force values were normalized to their maximum and expressed as percentages.Compared to the OKR, there was a mean 1.8 mm lateral shift of the patella when using the MAS, and a larger medial-lateral range of motion. Changing patella height yielded similar effects on patellar medial-lateral translation using the OKR and MAS rigs, baja caused a medial shift (2.4 mm versus 1.8 mm, respectively) and alta caused a very slight med, Résumé de la communication présentée lors du congrès international tenu conjointement par Canadian Society for Mechanical Engineering (CSME) et Computational Fluid Dynamics Society of Canada (CFD Canada), à l’Université de Sherbrooke (Québec), du 28 au 31 mai 2023.

Olawale A Sogbein,1,2 Jacquelyn D Marsh,1 Lyndsay E Somerville,1 James L Howard,1 Brent A Lanting1 1Division of Orthopaedic Surgery, Department of Surgery, London Health Sciences Centre – University Hospital, London, Ontario, Canada; 2Schulich School of Medicine & Dentistry, Western University, London, Ontario, CanadaCorrespondence: Olawale A Sogbein, Tel +1 519-476-1151, Email olsogbein@nosm.caBackground: We recently performed a clinical trial comparing motor sparing blocks (MSB) to periarticular infiltration (PAI) following total knee arthroplasty (TKA). We found that MSBs provided longer analgesia (8.8 hours) than PAI with retention of quadriceps strength, and with similar function, satisfaction, and length hospital stay. However, its potential increased cost could serve as a barrier to its adoption. Therefore, our aim was to compare the costs of MSBs to PAI following TKA.Methods: We conducted a retrospective review of data from our previous RCT. There were 82 patients included in the RCT (n = 41 MSB group, n = 41 PAI group). We compared the mean total costs associated with each group until hospital discharge including intervention costs, health-care professional service fees, intraoperative medications, length of stay, and postoperative opioid use.Results: Seventy patients were included (n = 35 MSB group, n = 35 PAI group). The mean total costs for the MSB group were significantly higher ($1959.46 ± 755.4) compared to the PAI group ($1616.25 ± 488.33), with a mean difference of $343.21 (95% CI = $73.28 to $664.11, p = 0.03). The total perioperative intervention costs for performing the MSB was also significantly higher; however, postoperative inpatient costs including length of stay and total opioid use did not differ significantly.Conclusion: Motor sparing blocks had significantly higher mean total and perioperative costs compared to PAI with no significant difference in postoperative inpatient costs. However, its quadricep sparing nature and previously

Olawale A Sogbein,1,2 Bryn O Zomar,1,3 Dianne M Bryant,3 James L Howard,1 Jacquelyn D Marsh,1 Brent A Lanting1 1London Health Sciences Centre – University Hospital, Division of Orthopaedic Surgery, Department of Surgery, London, Ontario, Canada; 2Schulich School of Medicine & Dentistry, Western University, London, Ontario, Canada; 3Faculty of Health and Rehabilitation Sciences, Western University, London, Ontario, CanadaCorrespondence: Olawale A Sogbein, Tel +1 519-476-1151, Email olsogbein@nosm.caIntroduction: Total knee arthroplasty (TKA) is one of the most successful procedures for the treatment of severe knee osteoarthritis. Various surgical approaches have been investigated in the hopes of improving postoperative outcomes. Two include the medial parapatellar (standard) and midvastus. As the midvastus approach does not disrupt the extensor mechanism, it may be advantageous for functional recovery, however length of stay and long-term function are similar between approaches. Tourniquet use during TKA has conflicting results in the literature. We hypothesized that a future trial comparing outpatient versus standard TKA could appropriately use either surgical approach with or without a tourniquet. Therefore, the objective of this pilot randomized trial was to compare postoperative pain, function, quality of life, and satisfaction between patients who underwent a medial parapatellar or midvastus approach for TKA ± tourniquet use.Methods: We conducted a randomized trial with a two-by-two factorial design to compare the medial parapatellar to the midvastus surgical approach for TKA ± tourniquet use. The Short Form-12 (SF-12), Western Ontario McMaster Osteoarthritis Index (WOMAC), and Knee Society Score (KSS) were collected at baseline, postoperatively at two, six, 12 weeks, and one year.Results: Eighty-three patients were included. Postoperative WOMAC scores were statistically but not clinically higher at six weeks and three months in favour of no tourniquet u

Background: Research has demonstrated an increased risk of falls after total hip arthroplasty (THA). Yet, people’s knowledge on falls risk factors and how falls prevention strategies are being used after THA have not been examined. If a person’s knowledge of falls and self-efficacy about falls prevention strategies is low this would indicate a pressing need for interventions to lessen risk. The study objectives were: 1) to determine the falls knowledge and what fall prevention strategies people used after (THA) and 2) to determine the outcomes of a falls risk assessment at 12-months after unilateral THA. Methods: Overall, 108 people completed the Falls Risk for Older People – Community Setting (FROP-Com) scale, a falls questionnaire (covered occurrence of falls, knowledge on falls risk factors, falls prevention strategies implemented after THA surgery), 6-m Walk Test (6mWT), 30-Second Chair Stand Test (30CST), Timed-up and Go (TUG) Test, and Activities-specific Balance Confidence Scale (ABC). Results: Twenty-five (23.2%) people fell at least once in the 12 months after THA. Scores on the FROP-Com ranged from 2–20 with an average of 8.2 ± 3.6 indicating a mild falls risk. The importance of falling compared to other health concerns was rated as moderate to high (6.8 ± 2.9) and the majority of participants (n = 98, 90.7%) believed falls can be prevented after THA. Total scores on the ABC scale ranged from 30.6% to 100.0% with an average score of 84.4 ± 15.5%, indicating high function. Only 47 people (43.5%) reported receiving falls prevention education. A total of 101 falls prevention strategies were completed by 67 people (62%), the most common strategy was environmental modifications (e.g., installation of grab bars) at 37.4%, while exercise was mentioned by only 2%. The majority of people had functional deficits in 30CST (62%) and TUG (76.9%) at 12-months after unilateral THA. Conclusions: Almost a quarter of the sample had experienced a fall in the 12-months after

Michael Decker,1 Amber Price,1 Aria Khalili,2 Robert Klassen,2 Mary Jane Walzak,3 Matthew Teeter,4– 7 Richard McCalden,8 Brent Lanting8 1Department of Orthopaedic Surgery, The University of New Mexico Health Sciences Center, University of New Mexico, Albuquerque, NM, USA; 2Department of Mechanical and Materials Engineering, Western University, London, Ontario, Canada; 3Surface Science Western, University of Western Ontario, London, Ontario, Canada; 4Department of Medical Biophysics, Schulich School of Medicine and Dentistry; 5Imaging Research Laboratories, Robarts Research Institute, Schulich School of Medicine and Dentistry; 6Surgical Innovation Program, Lawson Health Research Institute; 7Division of Orthopaedic Surgery, Schulich School of Medicine and Dentistry, Western University and London Health Sciences Centre, London, Ontario, Canada; 8Division of Orthopaedic Surgery, London Health Sciences Centre, University Hospital, London, Ontario, CanadaCorrespondence: Amber PriceDepartment of Orthopaedics, The University of New Mexico, Albuquerque, NM, 87131-0001, USATel +1 (505) 272-6472Fax +1 505 272-809Email ambprice@salud.unm.eduIntroduction: Numerous thermal free radical stabilization techniques are used in the production of highly cross-linked polyethylene (HXLPE) to improve oxidative stability. Little knowledge exists on the effects of in vivo time on the mechanical properties of HXLPE. The purpose of this study was to determine if free radical stabilization of HXLPE impacts mechanical properties as well as oxidative stability of acetabular liner rims after extended in vivo time.Methods: Retrieved and control remelted, single annealed and sequentially annealed HXLPE liner rims were tested for mechanical properties. Oxidation was measured with FTIR spectroscopy and crystalline phase composition measured with Raman spectroscopy.Results: No correlation was found between in vivo, ex vivo time and hardness for annealed groups. A statistically significant difference

Sahil Prabhnoor Sidhu, Brent Lanting, Paul Kelly, Edward Vasarhelyi, Ryan Willing Western University, Department of Orthopaedic Surgery, London, Ontario, N6A 5A5, CanadaCorrespondence: Sahil Prabhnoor Sidhu Email Prabhnoor.sidhu@ucalgary.caIntroduction: Trialling is a key step in total knee arthroplasty (TKA) and helps the surgeon assess for adequate balancing, range of motion, and stability. Despite this, there are no studies investigating knee kinematics when using trial versus final polyethylene tibial inserts.Materials and Methods: Fourteen fresh frozen cadaveric specimens were cycled in a VIVO joint motion simulator. Using both simple compression and simulated muscle loads, joints were tested after TKA with a trial insert or a final tibial poly insert. Anterior/posterior (AP), internal/external (IE), and varus/valgus (VV) kinematics and laxities were analyzed.Results: Knees with trial poly inserts had significantly greater AP hysteresis (difference between flexion and extension motion) than those with final poly inserts (p=0.001). There was no significant difference in IE (p=0.563) or VV (p=0.580) hysteresis. There was no difference in AP, IE, or VV motion or laxities when considering the flexion path alone. Prosthetic joints followed different paths in flexion versus extension.Conclusion: While trial tibial inserts impart valuable information, they may not accurately reproduce the same joint kinematics as final inserts. Balancing of the knee at specific degrees of flexion may depend on the path taken to get there.Keywords: knee, kinematics, arthroplasty, poly, trial

Paul Kooner, Taran Schubert, James L Howard, Brent A Lanting, Matthew G Teeter, Edward M Vasarhelyi Division of Orthopaedic Surgery, London Health Sciences Centre, University Hospital, Western University, London, ON, CanadaCorrespondence: Paul KoonerDivision of Orthopaedic Surgery, London Health Sciences Centre, University Hospital, Western University, 339 Windermere Road, London ON N6A 5A5, CanadaTel +1 519 685 – 8500Email kooner.paul@gmail.comBackground: Wearable step-counter devices have become inexpensive tools that enable patients, researchers, and clinicians to objectively monitor physical activity. It is unknown how the use of gait aids, such as canes, crutches, and walkers, affects the accuracy of these devices. Such gait aids are commonly used by patients with chronic physical impairment and after joint-replacement surgery. The aim of this study was to determine the effect of gait aids on the accuracy of wearable step counters.Methods: Nine healthy participants wore a Fitbit step counter on their wrist and hip and performed eight walking tests with canes, crutches, and walkers. Bland–Altman analyses were performed for all eight walking tests in order to compare agreement between measurement techniques.Results: Mean overall agreement for subjects walking without gait aids in the hip group was excellent, showing a bias of – 2.9, with limits of agreement (LOAs) between – 8.72 and 2.95. For use of canes or crutches, the Bland–Altman plots had a range of bias values between the hip and wrist counters from – 7.22 to 33.56, with LOAs from – 98.55 to 124.2. The wrist counter during the four-wheeled walking test showed very little agreement with the actual step count, with a bias value of 91.33 and LOAs of 64.1– 118.6, illustrating exceptionally unreliable step counts.Conclusion: This study suggests that these widely commercially available step counters have poor reliability with gait ai

Mina W Morcos,1 James L Howard,2 Brent Lanting,2 Steven MacDonald,2 Douglas Naudie,2 Richard McCalden,2 Edward M Vasarhelyi2 1Division of Orthopaedic Surgery, Department of Surgery, University of Toronto, Toronto, ON, Canada; 2Division of Orthopaedic Surgery, Department of Surgery, Western University London Health Sciences Center University Hospital, London, ON, CanadaCorrespondence: Edward M VasarhelyiDivision of Orthopaedic Surgery, Department of Surgery, Western University London Health Sciences Center University Hospital, 339 Windermere Road, PO Box 5339, London, Ontario N6A 5A5, CanadaTel +1 519 663-3413Fax +1 519 663-3417Email edward.vasarhelyi@lhsc.on.caPurpose: The necessity of stemmed components when performing a varus-valgus constrained (VVC) primary total knee arthroplasty (TKA) is unclear. The purpose of this study is to compare the outcomes of primary VVC TKA with and without stems at a minimum of two years.Methods: Patients in our prospectively collected database with primary VVC TKAs were identified. Patient demographics, prosthesis data, time in vivo, characteristics of revision, and radiographs and PROMs were compared between the stemmed and un-stemmed cohorts.Results: Sixty-five patients with 69 primary VVC TKAs were identified; 17 were implanted with stems and 52 without stems. Five of the stemmed TKAs (5/17) required revision at 15.1 years, while only one of the un-stemmed TKA (1/52) required a revision at 21.6 years (p=0.003) for aseptic loosening. Of the 5 stemmed TKAs requiring revision, 3 were for aseptic loosening and 2 were for PPJI. The un-stemmed cohort had a significantly higher final total KSS (p=0.048).Conclusion: There was no increase in aseptic loosening or revision surgery in patients with non-stemmed primary VVC TKA compared to those with stemmed VVC TKA at mid-term follow-up. Utilizing non-stemmed TKA with VVC in appropriate cases is safe and may reduce cost, shorten operative time, and preserve bone-stock.Keywords: total knee art

Douglas DR Naudie,1,2 Silvio Ndoja,1 Thomas J Wood,3 Lyndsay E Somerville,1 James L Howard,1,2 Richard W McCalden,1,2 Steven J MacDonald,1,2 Brent A Lanting1,2 1Division of Orthopaedic Surgery, Department of Surgery, London Health Sciences, London, Ontario, Canada; 2Bone and Joint Institute, Western University, London, Ontario, Canada; 3Division of Orthopaedic Surgery, Department of Surgery, Hamilton Health Sciences, McMaster University, Hamilton, Ontario, CanadaCorrespondence: Douglas DR NaudieDivision of Orthopaedic Surgery, Department of Surgery, Western University, Schulich School of Medicine, London Health Sciences Centre, University Campus, A9-028,339 Windermere Road, London, Ontario N6A 5A5, CanadaEmail Douglas.Naudie@lhsc.on.caIntroduction: Corrosion at the head–neck interface of modular components in total hip arthroplasty (THA) has been reported as a cause of failure of modern total hip replacement implants. While this method of failure has been well described, it remains poorly understood. The purpose of this study is to review the three most commonly used uncemented femoral stems at our institution over the last fifteen years and to correlate any established risk factors with rates of revision, particularly corrosion.Methods: We reviewed 2095 patients from March 2000 to September 2015 who underwent total hip arthroplasty with one of three uncemented femoral stem designs. All stems were made of a Ti6Al4V alloy with a 12/14 taper design. We included only those stems coupled with a CoCr head and a highly crosslinked polyethylene liner. We evaluated age, gender, body mass index (BMI), femoral head size, head length, neck angle and offset and correlated these to the incidence of all cause revision, as well as revision excluding infection.Results: There were no recognized corrosion-related revisions identified. There was no association between age, BMI, gender, head length, neck angle and offset to all cause revision or revision with infection exclud

Mohammad M Alzahrani,1 Thomas J Wood,2 Lyndsay E Somerville,3 Steven J MacDonald,3 James L Howard,3 Edward M Vasarhelyi,3 Brent A Lanting3 1Department of Orthopaedic Surgery, College of Medicine, Imam Abdulrahman Bin Faisal University, Dammam, Saudi Arabia; 2Division of Orthopaedic Surgery, Department of Surgery, Hamilton Health Sciences, McMaster University, Hamilton, ON, Canada; 3Division of Orthopaedic Surgery, Department of Surgery, London Health Sciences Centre University Campus, University of Western Ontario, London, Ontario N6A 5A5, CanadaCorrespondence: Mohammad M AlzahraniDepartment of Orthopaedic Surgery, College of Medicine, Imam Abdulrahman Bin Faisal University, 2835 King Faisal Road, Dammam 34212, Saudi ArabiaEmail mmalzahrani@iau.edu.saIntroduction: Outcomes and longevity of total knee arthroplasty (TKA) depend mainly on restoring knee function, through precise bony resection and appropriate soft tissue balancing. The current literature lacks evidence regarding the degree of radiographic change after intra-operative knee balancing. The purpose of our study was to assess the degree of change in coronal lower extremity alignment by comparing pre-operative to post-operative full-length radiographs (FLR) after quantifying the degree of intra-operative knee balancing and correlate patient-reported outcomes to the extent of balancing required.Patients and Methods: One hundred and fifty-four patients undergoing primary TKA for varus knee osteoarthritis were included in the study. The performed soft tissue releases and bony adjustments to obtain a balanced TKA intra-operatively were prospectively documented and were grouped into minimal, moderate and extensive release groups. Hip-knee-ankle angle (HKA), anatomical femoral-tibial angle (FTA), condylar hip angle (CH), medial proximal tibial angle (MPTA) and condylar plateau angle (CPA) were measured on full-length radiographs both pre-operatively and post-operatively. Frequencies of the soft tissue releases and

Bryn O Zomar, 1–3 Shannon L Sibbald, 1 Doug Bickford, 4 James L Howard, 2, 5 Dianne M Bryant, 1, 3 Jacquelyn D Marsh, 1, 3 Brent A Lanting 2, 3, 5  1Faculty of Health Sciences, University of Western Ontario, London, ON, Canada; 2London Health Sciences Centre, London, ON, Canada; 3Bone and Joint Institute, University of Western Ontario, London, ON, Canada; 4Southwestern Ontario Stroke Network, London, ON, Canada; 5Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON, CanadaCorrespondence: Brent A Lanting 339 Windermere Road, Rm B9-003, London, ON N6A 5A5, CanadaTel +1 519-663-3335Email brent.lanting@lhsc.on.caAbstract: Total joint arthroplasties (TJA) are successful procedures for the treatment of end-stage hip and knee arthritis. Length of stay in hospitals after these procedures has been steadily decreasing over time, with outpatient procedures (discharge on the same day as surgery) introduced in the US within the last 20 years. Reducing length of stay after TJA can provide cost savings. Centres in Canada have started to utilize outpatient TJA procedures, but we have identified some barriers that may have limited their implementation. We have summarized the current literature for outpatient TJA and discussed potential solutions for the current barriers.Keywords: total knee arthroplasty, total hip arthroplasty, outpatient, implementation, barriers