Fully constrained liners are used to treat recurrent dislocations or patients at high risk after total hip replacements. However, they can cause significant morbidities including recurrent dislocations, infections, aseptic loosening and fractures. We examine long term results of 111 patients with tripolar constrained components to assess their redislocation and failure rate. The purpose of this study was to assess survivorship, complications and functional outcomes at a minimum 10 years after the constrained tripolar liners used in our institute. We retrospectively identified 111 patients who had 113 revision tripolar constrained liners between 1998 and 2008. Eighty-nine were revised due to recurrent dislocations, 11 for pseudotumor with dysfunctional abductors, and 13 for periprosthetic infection with loss of soft tissue stabilizers. All patients had revision hip arthroplasty before the constrained liner was used: 13 after the first revision, 17 after the second, 38 after the third, and 45 had more than 3 revisions. We extracted demographics, implant data, rate of dislocations and incidence of other complications. Kaplan Meier curves were used to assess dislocation and failure for any reason. WOMAC was used to assess quality of life. At 10 years, the survival free of dislocation was 95.6% (95%CI 90- 98), and at 20 years to 90.6% (95% CI 81- 95.5). Eight patients (7.1%) had dislocations of their constrained liners: 1 patient had simultaneous periprosthetic infection identified at the time of open reduction, and 1 patient sustained stem fracture 3 months prior to the liner dislocation. At 10 years, the survival to any further surgery was 89.4% (95% CI 82–93.8), and at 20 years, this was 82.5 (95% CI 71.9–89.3). Five patients (4.4%) had deep infection: 4 of these had excision arthroplasty due to failure to control infection, while 1 patient was treated successfully with debridement, exchange of mobile components and intravenous antibiotics. Two patients (1.8%) had dissociated rings that required change of liner, ring and head. Two patients (1.8%) had periprosthetic femoral fractures that were treated by revision stems and exchange of constrained liners. The mean WOMAC functional and pain scores were 66.2 and 75.9 of 100, respectively. Constrained tripolar liners in our institute provided favourable results in the long term for recurrent dislocation hip arthroplasty with dysfunctional hip stabilizers. Infection in these patients can prove to be difficult to treat due to their poor soft tissue conditions from repeated surgeries. Comparing long terms results from other types of constrained liners is essential to evaluate these salvage liners.
A large proportion of wait times for primary total knee (TKA) and hip (THA) arthroplasty is the time from primary care referral to surgical consultation. To our knowledge, no study has investigated whether a referral Oxford Knee or Hip Score (OKHS) could be used to triage non-surgical referrals appropriately. The primary purpose of the current study was to determine if a referral OKHS has the predictive ability to discriminate when a knee or hip referral will be deemed conservative as compared to surgical by the surgeon during their first consultation, and to identify an OKHS cut-off point that accurately predicts when a primary TKA or THA referral will be deemed conservative. We retrospectively reviewed all consecutive primary TKA and THA consultations from a single surgeon's tertiary, high volume practice over a three-year period. Patients with a pre-consultation OKHS, BMI < 4 1, and no absolute contraindication to TJR were included. Consultation knees/hips were categorized into two groups based on surgeon's decision, those that were offered TJR during their first consolation (surgical) versus those that were not (conservative). Baseline demographic data and OKHS were abstracted. Variables of interest were compared between cohorts using the exact chi-square test and Wilcoxon rank-sum test. Spearman's rank correlation coefficients were used to measure association between pre-consult OKHS and the surgeon's decision. A receiver operator characteristic (ROC) curve analysis was used to calculate the area under the curve (AUC) and to identify a cut-off point for the pre-operative OKHS that identified whether or not a referral was deemed conservative. TKA and THA referrals were analyzed separately. The study included 1,436 knees (1,016 patients) with a median OKS of 25 (IQR 19–32) and 478 hips (388 patients) with a median OHS of 22 (IQR 16–29). Median pre-consultation OKHS demonstrated clinically and statistically significant differences between the surgical versus conservative cohorts (p 32 (sensitivity=0.997, NPV=0.992) and for hips is OHS >34 (sensitivity=0.997 NPV=0.978). ROC analysis identified severable potential lower OKHS thresholds, depending on weight of prioritization of sensitivity, specificity, and NPV. Referral OKS and OHS demonstrate good ability to discriminate when a primary TKA or THA referral will be deemed non-surgical versus surgical at their first consultation in a single surgeon's practice. Multiple potential effective OKHS thresholds can be applied as a tool to decrease wait times for primary joint arthroplasty. However, a cost analysis would aid in identifying the optimal cut-off score, and these findings need to be externally validated before they can be broadly applied.
High complication rates and poor outcomes have been widely reported in patients undergoing revision of large head metal-on-metal arthroplasty. A previous study from our centre showed high rates of dislocation, nerve injury, early cup loosening and pseudotumor recurrence. After noting these issues, we implemented the following changes in surgical protocol in all large head MOM revisions: One: Use of highly porous shells in all cases. Two: Use of largest femoral head possible. Three: Low threshold for use of dual mobility and constrained liners when abductors affected or absent posterior capsule. Four: Use of ceramic head with titanium sleeve in all cases. Five: Partial resection of pseudotumor adjacent to sciatic and femoral nerves. The purpose of the present study is to compare the new surgical protocol above to our previously reported early complications in this group of patients We specifically looked at (1) complications including reoperations, (2) radiologic outcomes, and (3) functional outcomes. Complication rates after (Group 1), and before (Group 2) modified surgical protocol were compared using Chi-square test, assuming statistical significance p < 0 .05. Major complications occurred in 4 (8.3%) of 48 patients who had modified surgical technique, compared to 12 (38%) of 32 revisions prior to modification (p < 0 .05). Two hips of 48 (4.17%) endured dislocations in Group 1, compared to 9 of 32 (28%) in Group 2 (p < 0 .05). Four patients of 48 had repeat revision in Group 1: 2 for recurrence of pseudotumor, 1 for dislocation, and 1 for infection, compared to 6 patients who had 7 repeat revisions of 32 patients in Group 2: 3 for acetabular loosening, 3 for dislocation, and 1 for recurrence of pseudotumor (p=0.1). None of 48 revisions in Group 1 had acetabular loosening, compared to 4 of 32 in Group 2 (p=0.02). Two patients had nerve injury in Group 2, compared to none in Group 1 (p=0.16). The mean WOMAC pain score was 87.1 of 100 and the function score was 88.4 of 100 in Group 1, compared to a mean WOMAC pain score of 78 of 100 (p=0.6) and a function score of 83 of 100 in Group 2 (p=0.8). Modification of the surgical techniques described in the introduction has resulted in a significant decrease in complications in revision of large head MOM total hips. We continue to use this protocol and recommend it for these difficult cases.
Dislocation after revision total hip is a common complication. The purpose of this study was to assess whether a large femoral head (36/40mm) would result in a decreased dislocation rate compared to a standard head (32mm). A randomized clinical trial was undertaken to assess the effect of large femoral heads on dislocation after revision total hip. Patients undergoing revision hip arthroplasty at seven centers were randomized to 32mm head or 36/40mm head. Patients were stratified according to surgeon. Primary endpoint was dislocation. Rates were compared with Fishers exact test. Secondary outcome measures were quality of life: WOMAC, SF-36 and satisfaction. One hundred eighty four patients were randomized: 92 in the 32mm head group and 92 in the large head group. Baseline demographics were similar in the two groups. Patients were followed from two to five years postoperativelyPurpose
Method
There is a postulated association between increased serum metal ions and pseudotumour formation in patients with metal-on-metal hip replacements. The primary aim of this study was to assess the prevalence of pseudotumour in 31 asymptomatic patients with a large femoral head (LFH) metal-on-metal hip implant. This was compared to the prevalence of pseudotumour in 20 matched asymptomatic patients with a hip resurfacing (HRA) and 24 matched asymptomatic patients with a standard metal-on-polyethylene (MOP) total hip. A secondary objective was to assess possible correlation between increased serum metal ions and pseudotumour formation Ultrasound examination of the three groups was performed at a minimum follow up of two years. Serum metal ions were measured in the metal-on-metal LFH and HRA groups at a minimum of two years.Purpose
Method
Measurements of patellar kinematics are essential to investigate the link between anterior knee pain following knee arthroplasty and patellar maltracking. A major challenge in studying the patellofemoral (PF) joint postoperatively is that the patellar component is only partially visible in the sagittal and close-to-sagittal radiographs. The narrow angular distance between these radiographs makes the application of conventional bi-planar fluoroscopy impossible. In this study a methodology has been introduced and validated for accurate estimation of the 3D kinematics of the PF joint post-arthroplasty using a novel multi-planar fluoroscopy approach. An optoelectronic camera (Optotrak Certus) was used to track the motion of an ISO-C fluoroscopy C-arm (Siemens Siremobil) using two sets of markers attached to the X-ray source and detector housings. The C-arm was used in the Digital Radiography (DR) mode, which resembles an ordinary X-ray fluoroscopy image. A previously-developed technique (Cho et al., 2005; Daly et al., 2008) was adapted to find the geometric parameters of the imaging system. Thirty-eight DRs of the calibration phantom were obtained for the 190 of rotation of the C-arm at 5 rotational increments while data from motion markers were recorded continuously at a frequency of 100 Hz. A total knee replacement prosthesis was implanted on an artificial bone model of the knee, and the implant components and bones were rigidly fixed in place using a urethane rigid foam. For the purpose of validation, positions of the implant components were determined using a coordinate measuring machine (CMM). Sagittal and obliquely sagittal radiographs of the model were taken where the patellar component was most visible. For each DR the geometric parameters of the system were interpolated based on the location of the motion markers. The exact location of the projection was then determined in 3D space. JointTrack Bi-plane software (Dr. Scott Banks, University of Florida, Gainesville) was used to conduct 2D-3D registration between the radiographs and the reverse-engineered models of the implant components. Results of the registration were directly compared to the ground-truth obtained from the CMM to calculate the accuracies.Purpose
Method
The outcome following isolated liner exchange for revision knee arthroplasty, while an attractive option for its simplicity, has a mixed outcome reported in the literature. We report our experience in patients who had a minimum of two years follow-up. From our database we identified 44 cases in 41 patients who had an isolated liner exchange for a failed primary knee replacement. Twenty were female and the mean body mass index was 33 (range 20 to 49). The mean time to revision from their index procedure was 76 months (range 8 to 152). The mean age at revision was 69 years (range 45 to 90). Patients were assessed by use of validated quality of life questionnaires: Oxford-12, UCLA Activity Level, WOMAC and SF-12. Patients current scores were compared to pre-operative scores in 19 cases. Radiographs were assessed for polyethylene wear, osteolysis and alignment with respect to the mechanical axis. Intra-operative findings were compared to radiographic findings.Purpose
Method
The purpose of this study was to compare and evaluate the cost-effectiveness of the MIS Anterolateral Approach to that of the MIS Posterolateral and MIS Direct Lateral Approach. A prospective randomized control trial was designed and conducted to compare the MIS Anterolateral Approach to that of the MIS Posterolateral and MIS Direct Lateral Approach. Contemporary methods for economic evaluation were used to ascertain direct and indirect costs (in Canadian dollars) along with clinical effectiveness outcomes (SF6D and Pat5D utility measures). University and hospital ethics was obtained and patients were recruited and consented to participate in the RCT resulting in the assignment of 130 patients MIS hip arthroplasty procedures. Baseline patient demographics, comorbidity, quality of life, and utility were obtained for all patients. In-hospital costing data was obtained including operating room and patient room costs as well as medication, rehab and complications. Post-discharge costs were calculated from direct and indirect costs of medication, rehab, medical costs and complications until one year post-operatively. Clinical effectiveness measures were administered at intervals until one year post-operatively.Purpose
Method
