Total knee arthroplasty (TKA) has proven clinical success with reported longterm survivorship of 92% in the elderly population. Concerns regarding increased loosening rates and potential need for multiple revision surgeries in patients younger than 60 years have traditionally discouraged TKA in younger patients. The purpose of this study was to review the longterm clinical and radiographic results of patients under the age of 45 yrs who underwent a total knee replacement. A retrospective review of our institutional database was performed between January 1996 and December 2004 The criteria for inclusion in the study were as follows: age 45 years or younger at index arthroplasty, cemented condylar prosthesis, and a minimum follow-up of 9 years. A total of 39 consecutive primary cemented condylar knee arthroplasties in patients with end stage arthritis were performed in 36 patients who were 45 years or younger. The median length of followup was 13.6 years. There were 18 men and 21 women. The mean age was 40.6 years (range, 28–44). There were 23 right, 16 left, and 3 bilateral procedures. The mean body mass index was 31.2 kg/m2 Clinical and radiological evaluations were performed before surgery and at 6 weeks, 3 months, 1 year and every 2 years subsequently. Knee scores were calculated using the Knee Society Clinical Rating Scores (KSCRS), SF-12 and WOMAC scores to assess pre, and post-operative function. Postoperative anteroposterior and lateral views were assessed for femoral and tibial component position, alignment, and presence or progression of radiolucent lines at the bone-cement and prosthesis-cement interfaces Statistical analysis was performed using the 2-sample test or Wilcoxon rank sum test for comparison of continuous variables. Kaplan-Meier analysis of implant survival was performed with failure defined as femoral component revision due to any cause.Introduction
Materials and Methods
The effect of polyethylene wear and lift-off between the tibial and femoral components on the mechanical axis was assessed in primary TKA (Total Knee Arthroplasty) based on retrieval data and full leg radiographs. Controversy exist regarding performing a TKA with component placement in physiologic versus neutral alignment. Some literature indicates good survivorship and superior clinical outcome in undercorrected TKA's for varus osteoarthritic knees. However, other literature indicates decreased survivorship and coronal plane alignment is still one of the contributing factors to wear in total knee arthroplasty (TKA). The two determinants of the intra-articular deformity in TKA arepolyethylene wear and lift-off between the tibial and femoral compartment. The goal of this study was to evaluate the impact of wear and lift-off on the mechanical axis in neutral and varus aligned TKA's.Summary
Introduction
Increased modularity of total hip arthroplasty components has occurred, with theoretical advantages and disadvantages. Recent literature indicates the potential for elevated revision rates of modular neck systems and the potential for metallosis and ALVAL (Aseptic Lymphocyte dominated Vasculitis Associated Lesion) formation at the modular neck/stem site. Retrieval analysis of one modular neck implant design including SEM (Scanning Electron Microscopy) assessment was done and correlated to FEA (Finite Element Analysis) as well as clinical features of patient demographics, implant and laboratory analysis. Correlation of the consistent corrosion locations to FEA indicates that the material and design features of this system may result in a biomechanical reason for failure. The stem aspect of the modular neck/stem junction may be at particular risk.
Fast track arthroplasty regimens require preservation of motor power to perform early rehabilitation and ensure early discharge (1). Commonly performed nerve blocks like femoral and Sciatic nerve blocks results in motor weakness thereby interfering with early rehabilitation and may also predispose to patient falls (2, 3). Hence, targeting the terminal branches of the femoral and sciatic nerves around the knee joint under ultrasound is an attractive strategy. The nerve supply of interest for knee analgesia are the terminal branches of the femoral nerve, the genicular branches of the lateral cutaneous nerve of thigh, obturator and sciatic nerves (4). We modified the performance of the adductor canal block and combined it with US guided posterior pericapsular injection and lateral femoral cutaneous nerve block to provide analgesia around the knee joint. The femoral artery is first traced under the sartorius muscle until the origin of descending geniculate artery and the block is performed proximal to its origin. A needle is inserted in-plane between the Sartorius and rectus femoris above the fascia lata and 5 ml of 0.5% ropivacaine (LA) is injected to block the intermediate cutaneous nerve of thigh. The needle is then redirected to enter the fascia of Sartorius to deliver an additional 5ml of LA to cover the medial cutaneous nerve of thigh following which it is further advanced till the needle tip is seen to lie adjacent to the femoral artery under the Sartorius to perform the adductor canal block with an additional 15–20 ml of LA to cover nerve to vastus medialis, saphenous nerve and posterior division of the obturator nerve (Fig 1). The lateral cutaneous nerve of thigh is optionally blocked with 10 ml of LA near the anterior superior iliac spine between the origin of Sartorius and tensor fascia lata (Fig 2). The terminal branches of sciatic nerve to the knee joint is blocked by depositing 25 ml of local anesthetic solution between the popliteal artery and femur bone at the level of femoral epicondyles (Fig 3).Introduction
Methods
Coronal plane alignment is one of the contributing factors to polyethylene wear in total knee arthroplasty (TKA). The goal of this study was to evaluate the wear and damage patterns of retrieved tibial polyethylene inserts in relationship to the overall mechanical alignment and to the position of the tibial component. Based on full-length radiographs, ninety-five polyethylene inserts retrieved from primary TKA's with a minimum time in-vivo of five years were analysed for wear and damage. Four alignment groups were compared: valgus, neutral, mild varus and moderate varus. Varus and valgus positioning of the tibial component was analysed for damage score for the neutral and varus aligned groups.Introduction
Materials and methods
Beadmill processing combined with automated blood culture bottle methods (BACTEC™) has a greater sensitivity and specificity, and a shorter time to positivity compared with primary plates (PP) for prosthetic joint infection (PJI) diagnosis but the clinical impact of Bactec on antimicrobial therapy has not yet been evaluated. We compared time-to-positivity of Columbia agar with horse blood plates (BA) and chocolatized horse blood plates (CHOC) versus anaerobic (ANA) and aerobic blood culture bottles (02) in patients with PJI. We compared the contributions of the two methods to the commencement of effective and targeted antimicrobial therapy. Retrospective observational study from June 2013 to March 2014. Inclusion criteria were confirmed PJI (IDSA criteria) with at least 2 perioperative samples. After beadmill processing BA and CHOC plates were incubated for 2 days and discarded if negative, BactecTM bottles were incubated for 14 days and sub-cultured if positive. MALDI-TOF (Microflex, Brucker) was used for identification and all isolates had sensitivities performed (Phoenix, BD). Standard empirical antibiotic treatment was teicoplanin, piperacillin/tazobactam and amikacin. We defined time to switch as difference between date of sample collection and date of commencing targeted or effective therapy; prior antibiotic therapy was defined as the use of antibiotics within 14 days before samples collection. Fifty cases were identified during the study period. 330 microbiological isolates were included: 24 (7.3%) were considered contaminants; 153 isolates (50.0%) were detected both from BactecTM and PP; 152 (49.7%) from BactecTM only; 1 isolate (0.3%) from PP only. 17 (34%) diagnoses of PJI was made exclusively by BactecTM. The majority of isolates on BA and CHOC plates grew in the first 24 hours (81.2% and 77.5% respectively). 293/305 isolates from BactecTM (96.1%) grew in the first 2 days. Antibiograms were available after 2.5 days from PP versus 4 days from BACTEC (p<0.0001). When we compared time to switch from empiric to targeted therapy, no difference was seen between patients with positive BACTEC cultures only (median 4 days, range 2–15) versus patients with positive PP cultures, (median 5 days, range 2–9) (p=0.984). Where organisms were resistant to empirical therapy, PP results did not contribute to switching to effective therapy. Prior antibiotic therapy had no impact on time-to-positivity for both methods (R=−0.005, p=0.936). Compared to BACTEC cultures for the diagnosis of PJIs, primary plate cultures did not provide additional diagnostic information and did not significantly reduce the time to effective or targeted antimicrobial therapy.
The pros and cons of general anesthesia versus spinal anesthesia in total hip arthroplasty has been a long debated topic. The purpose of this study was to compare the surgical times, blood loss and transfusion requirements between anesthetic types in patients undergoing primary total hip arthroplasty. A consecutive series of 1600 THA procedures with complete preoperative and postoperative data were evaluated. Twenty eight percent of procedures were performed with a general anesthetic (GA), 67% with a spinal anesthetic (SP) and 5% with a combination of the two. Outcomes were compared and tested for significance using the Independent Samples Kruskal Wallis or Pearson Chi-Square analysis.Purpose
Method
The patella provides a mechanical advantage to the knee extensor mechanism. Patellectomy, performed for trauma or patellofemoral arthrosis, does not preclude the development of tibiofemoral arthrosis. Total knee arthroplasty is the mainstay of treatment for tibiofemoral arthrosis. The purpose of this study was to evaluate the outcomes of total knee arthoplasty in patients who previously underwent patellectomy. A retrospective analysis was completed on a prospectively collected database to identify all patients who underwent total knee arthroplasty following a previous patellectomy. Sixty-one total knee arthroplasties in 57 patients were identified. Patient demographics as well as functional outcome scores, including WOMAC and Knee Society Scores, were evaluated.Purpose
Method
Spinopelvic parameters describe the orientation, shape, and morphology of the spine and pelvis. These parameters change during the first 10 years of life in children without spinal deformity; however, spinopelvic parameters have yet to be defined in children with significant early-onset scoliosis (EOS). Sagittal plane alignment could affect the natural history and outcome of interventions for EOS. As a result, spinopelvic parameters are being defined for this population. On the basis of the landmarks used for measurement of these parameters, there may be inherent error in performing these measurements on the immature pelvis. The purpose of this study is to define the variability associatedwith the measurement of spinopelvic parameters in children with EOS. Standing, lateral radiographs of 11 patients with untreated EOS were evaluated. Sagittal spinopelvic parameters (pelvic incidence [PI], pelvic tilt [PT], sacral slope [SS], and modified pelvic radius angle [PR]) were measured. To assess intraobserver reliability, these measurements were repeated 15 days apart. To define interobserver reliability, radiographs were measured by 2 independent observers.Introduction
Methods
The purpose of this study was to determine the prevalence of non-accidental injury in toddlers (birth to two years old) presenting with a femur fracture to a single institution within a Western Canadian population. There are currently no Canadian studies that investigate this association in the medical literature. A retrospective case-control study was performed for children less than or equal to two years of age with a diagnosis of femur fracture who presented to a single institution from 1994 to 2005. Patients with associated pathological or metabolic bone disorders were excluded. The primary outcome measure was the prevalence of non-accidental injury associated with femur fracture. Secondary outcome measures included: patient demographics, injury characteristics, radiologic and other work-up, and suspicion of abuse. Statistical analysis was performed using tests of analysis of variance and multivariate analysis to identify independent and significant risk factors associated with non-accidental injury. One hundred twenty-seven children that met the inclusion criteria were identified. The overall prevalence of non-accidental injury was 11% (14/127 patients) and 17% (10/60 patients) in children under twelve months. Mean age was twelve months in the abused group and sixteen months in the accidental group. Forty-three percent of the abused group had delayed presentation compared to 8% of the accidental group. In the abused group, 43% had unknown, unwitnessed, inconsistent histories versus 4% in the accidental group. No specific fracture pattern or location suggestive for non-accidental injury was identified. Forty-three percent (6/14 patients) of the abused group and 12% (13/113 patients) of the accidental group had other injuries. Multivariate analysis determined that delayed presentation (p=0.001), mechanism of injury (p=0.02) and other associated injuries (p=0.003) were the only independently significant risk factors for abuse. Toddlers who present with femoral fracture are at risk for associated non-accidental injury though perhaps this risk is not as high as previously thought. Regardless, a high index of suspicion is mandatory when these children are encountered and careful screening with a thorough history, physical examination, and other investigations where indicated, are warranted to rule out associated child abuse.
The purpose of this study was to first determine if neuromuscular scoliosis results in greater peri-operative transfusion requirements compared to idiopathic scoliosis, and secondly to compare the effects of tranexamic acid (TXA) dosing on reducing transfusion requirements in scoliosis surgery. Previous studies have suggested that patients with neuromuscular scoliosis tend to have more blood loss during scoliosis corrective surgery as compared to patients with idiopathic scoliosis. Tranexamic acid has not been studied extensively in these populations and consensus regarding appropriate dosing has not yet been elucidated. A retrospective chart review of all patients who underwent posterior instrumentation and fusion for scoliosis for the years 1999 to 2006 was performed. Peri-operative transfusion requirements for idiopathic and neuromuscular scoliosis patients were compared and grouped according to TXA use. Transfusion requirements for those patients receiving either a low (10mg/kg loading, 1mg/kg/h infusion) or high (20mg/kg loading, 10mg/kg/h infusion) dose TXA were also compared. Idiopathic patients had significantly decreased transfusion requirements overall (no TXA: idiopathic 1028.3 ± 558.7ml vs. neuromuscular 1400.7 ± 911.3ml, p = 0.02; with TXA: idiopathic 1082.9 ± 1005.5ml vs. neuromuscular 2043.8 ± 1397.5ml, p = 0.03). In the idiopathic group, high dose TXA resulted in a significant reduction in peri-operative transfusion requirements compared to low dose TXA (687.9 ± 778.1ml vs. 1355.0 ± 965.8ml, p = 0.04). Neuromuscular scoliosis patients have significantly higher transfusion requirements as compared to idiopathic patients. For patients with idiopathic scoliosis, the use of the high dose TXA is suggested over low dose TXA given the relative reduction in transfusion requirements for the high dose group.
The purpose of this study was to determine contact patterns in cementless acetabular cups using a novel computed tomography (CT) scan analysis technique. Eighteen embalmed cadaveric hemipelvis specimens were randomly assigned to receive one of three cup designs. A custom CT platform was designed to optimize imaging of the acetabular cups. After cup implantation, specimens were mounted on the platform and imaged in a spiral CT scanner. Contact analysis was preformed using custom-developed imaging software. The hemisphere, dual geometry and spiked cup designs analyzed using this CT analysis technique demonstrate differences in the amount and distribution of bone pros-thesis contact. The purpose of this study was to determine contact patterns in cementless acetabular cups using computed tomography (CT) scan analysis. Eighteen embalmed cadaveric hemipelvis specimens were randomly assigned to receive a hemispherical cup, a dual geometry cup, or a spiked cup. After radiographic templating, an experienced orthopaedic team prepared the specimens and implanted the acetabular cups. A custom CT platform was designed to optimize imaging of the acetabular cups. After cup implantation, specimens were mounted on the platform and imaged in a spiral CT scanner. Contact analysis was preformed using custom-developed imaging software. Contact was defined as a bone-prosthesis distance of 0.5 mm or less. The mean amount of cup contact was 40.4% (SD=8.2%) in the hemisphere group, 24.7% (SD=2.3%) in the dual geometry group, and 29.7% (SD=9.5%) in the spiked group. Colour mapping of the bone-prosthesis gap was used to identify contact/non-contact regions along the acetabular contour for all cup designs. Preliminary work with this CT analysis technique demonstrates differences in the amount and distribution of contact in the acetabular cup designs. Future work will involve development of an imaging phantom to clarify error, use of the technique with different cup designs and reaming techniques, and comparison of this technique with conventional CT scan techniques. This study outlines a novel CT analysis technique for quantitatively determining bone-prosthesis contact for cementless acetabular cups. The hemisphere, dual geometry and spiked cup designs analyzed using this CT analysis technique demonstrate differences in the amount and distribution of bone prosthesis contact.
