Complications of fixed infrared emitters in computer-assisted total knee arthroplasties

<p>Abstract</p> <p>Background</p> <p>The first stage in the implant of a total knee arthroplasty with computer-assisted surgery is to fasten the emitters to the femur and the tibia. These trackers must be hard-fixed to the bone. The objectives of our study are to evaluate the technical problems and complications of these tracker-pins, the necessary time to fix them to the bone and the possible advantages of a new femoral-fixed tracker-pin.</p> <p>Methods</p> <p>Three hundred and sixty seven tracker-pins were used in one hundred and fifty one computer-assisted total knee replacements. A bicortical screw was used to fix the tracker to the tibia in all cases; in the femur, however, a bicortical tracker was used in 112 cases, while a new device (OrthoLock) with percutaneous fixation pins was employed in the remaining 39.</p> <p>Results</p> <p>Technical problems related to the fixing of the trackers appeared in nine cases (2.5%). The mean surgery time to fix the tracker pin to the tibia was 3 minutes (range 2–7), and 5 minutes in the case of the femoral pin (range: 4–11), although with the new tool it was only three minutes (range 2–4) (p < 0.001). No complications were observed with this new device.</p> <p>Conclusion</p> <p>The incidence of problems and complications with the fixing systems used in knee navigation is very small. The use of a new device with percutaneous pins facilitates the fixing of femoral trackers and decreases the time needed to place them.</p

Improving the quality of orthopaedic elective and trauma operative notes: A completed audit loop study

Introduction: Good medical practice dictates that comprehensive documentation of all surgical procedures is paramount in maintaining a high standard of patient care. This study audited the quality of operative note keeping for elective and trauma procedures against the standards set by the British Orthopaedic Association (BOA) and The Royal College of Surgeons of England (RCSE) guidelines. Patients and methods: A retrospective assessment of the operative notes of every patient undergoing a total knee and hip replacement (elective cases) was carried out over a period of 2 months. Data recorded were compared against BOA guidelines. Within this time a randomised selection of trauma operative notes were also assessed, and the recorded data were compared against RCSE guidelines. Change in practice was implemented and the audit cycle completed. A total of 173 operative notes were evaluated. Results: There was a significant improvement (p-value < 0.05) in the quality of total knee replacement notes, with an increase in the percentage of data points from 68.6% to 93%. Similarly the quality of total hip replacement notes showed significant improvement (p-value < 0.01) with an increase in the percentage of data points from 67.5% to 86%. However trauma operative notes showed minimal improvement. Discussion: This study showed that the quality of elective operative notes was improved through surgeon education and the circulation of a guideline based electronic operative note. We have further plans to implement procedure specific notes for the most common types of trauma cases to help improve the quality of trauma operative notes

Outcomes of Charnley total hip arthroplasty using improved cementing with so-called second- and third-generation techniques

AbstractBackgroundTechniques of cemented total hip arthroplasty have developed over time. We present the outcomes of Charnley total hip arthroplasty performed using improved second- and third-generation cementing techniques.MethodsWe reviewed the radiologic results of 91 Charnley total hip arthroplasties performed using second- and third-generation cementing techniques. Second-generation techniques involved making multiple anchor holes, a double-cementing method on the acetabular side and an intramedullary plug, and retrograde filling with a cement gun on the femoral side in 57 hips. Third-generation techniques involved additional vacuum mixing and cement pressurization in 34 hips.ResultsJoint survival rates at 20years when using second-generation techniques were 89% for the socket and 94% for the stem with aseptic loosening as the end point; the survival rates at 10years when using third-generation techniques were 97 and 100%, respectively. According to our radiographic evaluation system for the clear zone at 5years, there was less clear zone in the acetabular side with the third-generation techniques than with second-generation techniques. In the femoral side, there was very little development of the clear zone, but the difference between generations was not significant.ConclusionsSecond- and third-generation cementing techniques showed excellent survivorship. The clear zone scores at 5years indicated that third-generation techniques were effective, especially in the acetabular side, and may produce better long-term results than second-generation techniques

Proportional-odds models for repeated composite and long ordinal outcome scales

In many medical studies, researchers widely use composite or long ordinal scores, that is, scores that have a large number of categories and a natural ordering often resulting from the sum of a number of short ordinal scores, to assess function or quality of life. Typically, we analyse these using unjustified assumptions of normality for the outcome measure, which are unlikely to be even approximately true. Scores of this type are better analysed using methods reserved for more conventional (short) ordinal scores, such as the proportional-odds model. We can avoid the need for a large number of cut-point parameters that define the divisions between the score categories for long ordinal scores in the proportional-odds model by the inclusion of orthogonal polynomial contrasts. We introduce the repeated measures proportional-odds logistic regression model and describe for long ordinal outcomes modifications to the generalized estimating equation methodology used for parameter estimation. We introduce data from a trial assessing two surgical interventions, briefly describe and re-analyse these using the new model and compare inferences from the new analysis with previously published results for the primary outcome measure (hip function at 12 months postoperatively). We use a simulation study to illustrate how this model also has more general application for conventional short ordinal scores, to select amongst competing models of varying complexity for the cut-point parameters

Computer Assisted Navigation in Knee Arthroplasty

Computer assisted surgery (CAS) was used to improve the positioning of implants during total knee arthroplasty (TKA). Most studies have reported that computer assisted navigation reduced the outliers of alignment and component malpositioning. However, additional sophisticated studies are necessary to determine if the improvement of alignment will improve long-term clinical results and increase the survival rate of the implant. Knowledge of CAS-TKA technology and understanding the advantages and limitations of navigation are crucial to the successful application of the CAS technique in TKA. In this article, we review the components of navigation, classification of the system, surgical method, potential error, clinical results, advantages, and disadvantages

Two-stage revision for prosthetic joint infection: predictors of outcome and the role of reimplantation microbiology

We describe rates of success for two-stage revision of prosthetic joint infection (PJI), including data on reimplantation microbiology. Methods: We retrospectively collected data from all the cases of PJI that were managed with two-stage revision over a 4 year period. Patients were managed with an antibiotic-free period before reimplantation, in order to confirm, clinically and microbiologically, that infection was successfully treated. Results: One hundred and fifty-two cases were identified. The overall success rate (i.e. retention of the prosthesis over 5.75 years of follow-up) was 83%, but was 89 % for first revisions and 73 % for re-revisions [hazard ratio2.9, 95 % confidence interval (CI) 1.2–7.4, P0.023]. Reimplantation microbiology was frequently positive (14%), but did not predict outcome (hazard ratio1.3, 95 % CI 0.4–3.7, P0.6). Furthermore, most unplanned debridements following the first stage were carried out before antibiotics were stopped (25 versus 2 debridements). Conclusions: We did not identify evidence supporting the use of an antibiotic-free period before reimplantation and routine reimplantation microbiology. Re-revision was associated with a significantly worse outcome

The Elite-Plus stem migrates more than the flanged Charnley stem: A clinical, radiographic, and radiostereometric analysis of 114 patients with an average of 7 years follow-up

Background and purpose The Charnley Elite-Plus stem was introduced in 1993 as a presumed improvement of the flanged Charnley stem. We started this study in 1996 to investigate the migratory pattern of the Elite-Plus stem. Patients and methods We followed 114 patients with osteoarthritis and a primary total hip replacement with the Elite-Plus stem. Mean age at the time of operation was 64 (50-76) years. The mean follow-up time was 6.5 (2-7) years. Radiographs were evaluated with respect to cementing technique, migration, and wear measured by radiostereometry (RSA). Results The stem survival was 98% (CI: 96-100) at 7 years and 92% (CI: 86-97) at 10 years. Mean migration of the femoral head was 0.35 mm (SD 0.3) medially, 0.51 mm (SD 0.6) distally, and 1.1 mm (SD 1.8) in the dorsal direction. Mean total point motion was 1.7 mm (SD 1.7). The migration of the stems stabilized after 5 years in the medial and dorsal directions, but continued to subside slightly. Migration along any of the axes was higher if the cementing technique was inferior. Interpretation Patients with a Charnley Elite-Plus stem and defects in the cement mantle or other signs of inferior implantation technique should be carefully monitored