Hollywood Specialist Medical Centre, 8/95 Monash Avenue, Nedlands, Western Australia 6009, Australia. email@example.com
The advent of computer-assisted knee replacement surgery has focused interest on the alignment of the components. However, there is confusion at times between the alignment of the limb as a whole and that of the components. The interaction between them is discussed in this article. Alignment is expressed relative to some reference axis or plane and measurements will vary depending on what is selected as the reference. The validity of different reference axes is discussed. Varying prosthetic alignment has direct implications for surrounding soft-tissue tension. In this context the interaction between alignment and soft-tissue balance is explored and the current knowledge of the relationship between alignment and outcome is summarised.
Acta Orthop. 2012 Feb ;83 (1):53-8 22112153
Department of Orthopedic Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
BACKGROUND AND PURPOSE Identification of the center of the femoral head in the coronal plane is essential during total knee arthroplasty. We evaluated a new method for localization of the center of the hip, thereby detecting the neutral mechanical axis using inter-femoral head center distances (X) measured from a radiograph. Our proposed method was compared with 3 commonly used methods using landmarks that are estimated to be 2 finger-breaths medial to the anterosuperior iliac spine (method A), 2.5 cm perpendicular to the mid-inguinal point (method I), and 1.5 cm lateral to the femoral artery (method F). METHODS 114 patients undergoing total knee arthroplasty were prospectively enrolled in the study. Four landmarks were marked and conventional anterior-posterior pelvic radiographs were taken. On the radiograph, the distance between the estimated FHC and the neutral mechanical axis was measured. RESULTS The median value (mm) of the measured distance was 9 in A, 7 in I, 8.5 in F, and 5 in X. When an error of more than 3° from neutral alignment was defined as an outlier, 15% of measurements in A, 6% of measurements in I, 14% in F, and 2% in X would fall in the outlier zone. INTERPRETATION The method detecting the neutral mechanical axis using inter-femoral head center distances (X) showed the least variability and the lowest percentage of outliers.
Improved accuracy of alignment with patient-specific positioning guides compared with manual instrumentation in TKA.
Department of Orthopaedics, The Ohio State University Medical Center, Columbus, OH, USA.
BACKGROUND Coronal malalignment occurs frequently in TKA and may affect implant durability and knee function. Designed to improve alignment accuracy and precision, the patient-specific positioning guide is predicated on restoration of the overall mechanical axis and is a multifaceted new tool in achieving traditional goals of TKA. QUESTIONS/PURPOSES We compared the effectiveness of patient-specific positioning guides to manual instrumentation with intramedullary femoral and extramedullary tibial guides in restoring the mechanical axis of the extremity and achieving neutral coronal alignment of the femoral and tibial components. METHODS We retrospectively reviewed 569 TKAs performed with patient-specific positioning guides and 155 with manual instrumentation by two surgeons using postoperative long-leg radiographs. For all patients, we assessed the zone in which the overall mechanical axis passed through the knee, and for one surgeon's cases (105 patient-specific positioning guide, 55 manual instrumentation), we also measured the hip-knee-ankle angle and the individual component angles with respect to their mechanical axes. RESULTS The overall mechanical axis passed through the central third of the knee more often with patient-specific positioning guides (88%) than with manual instrumentation (78%). The overall mean hip-knee-ankle angle for patient-specific positioning guides (180.6°) was similar to manual instrumentation (181.1°), but there were fewer ± 3° hip-knee-ankle angle outliers with patient-specific positioning guides (9%) than with manual instrumentation (22%). The overall mean tibial (89.9° versus 90.4°) and femoral (90.7° versus 91.3°) component angles were closer to neutral with patient-specific positioning guides than with manual instrumentation, but the rate of ± 2° outliers was similar for both the tibia (10% versus 7%) and femur (22% versus 18%). CONCLUSIONS Patient-specific positioning guides can assist in achieving a neutral mechanical axis with reduction in outliers.
Department of Orthopedics and Traumatology, CTO/M. Adelaide Hospital, Turin, Italy. firstname.lastname@example.org
BACKGROUND Total knee arthroplasty (TKA) is the appropriate treatment for degenerative pathology of the knee. Implant surveillance is mandatory to improve clinical results. We present the long-term results of a series of consecutive TKA Press Fit Condylar (J&J), cemented fixed bearing with selective patellar resurfacing in nonselected patients. MATERIALS AND METHODS In this prospective case series, 223 TKA were clinically and radiographically evaluated using the Hospital for Special Surgery (HSS) knee score and the Knee Society Roentgenographic Evaluation and Scoring System. RESULTS There were 197 patients, with an average age of 68.4 years [95% confidence interval (CI) 52.7-84.1 years]; 49 arthroplasties were implanted in men (21.1%) and 184 (78.9%) in women. The average follow-up was approximately 13.5 years (162.1 months; 95% CI 132.3-191.9), and it was possible to evaluate 179 implants (76.8% of the implanted prosthesis) in 176 patients. The average HSS score increased from 61.5 (95% CI 60.4-62.7) to 89.4 (95% CI 87.7-.93.5) points. The cumulative average survival rate at 15 years (the endpoint being failure with revision) was 90.6% ± 2% standard deviation. Resurfacing the patella did not make a difference in terms of implant survival. Progressive radiolucent lines were observed around 20 implants (14.3%); all were revised. CONCLUSIONS The PFC system is an excellent prosthetic solution. Early clinical complications, mechanical axis and patellar resurfacing do not correlate with implant failure, whereas progressive radiolucent lines do.
The Chitranjan Ranawat award: is neutral mechanical alignment normal for all patients? The concept of constitutional varus.
Department of Orthopaedic Surgery, University Hospital Pellenberg, Weligerveld 1, 3012 Pellenberg, Belgium. email@example.com
BACKGROUND Most knee surgeons have believed during TKA neutral mechanical alignment should be restored. A number of patients may exist, however, for whom neutral mechanical alignment is abnormal. Patients with so-called "constitutional varus" knees have had varus alignment since they reached skeletal maturity. Restoring neutral alignment in these cases may in fact be abnormal and undesirable and would likely require some degree of medial soft tissue release to achieve neutral alignment. QUESTIONS/PURPOSES We investigated what percentage of the normal population has constitutional varus knees and what are the contributing factors. SUBJECTS AND METHODS We recruited a cohort of 250 asymptomatic adult volunteers between 20 and 27 years old for this cross-sectional study. All volunteers had full-leg standing digital radiographs on which 19 alignment parameters were analyzed. The incidence of constitutional varus alignment was determined and contributing factors were analyzed using multivariate prediction models. RESULTS Thirty-two percent of men and 17% of women had constitutional varus knees with a natural mechanical alignment of 3° varus or more. Constitutional varus was associated with increased sports activity during growth, increased femoral varus bowing, an increased varus femoral neck-shaft angle, and an increased femoral anatomic mechanical angle. CONCLUSIONS An important fraction of the normal population has a natural alignment at the end of growth of 3° varus or more. This might be a consequence of Hueter-Volkmann's law. Restoration of mechanical alignment to neutral in these cases may not be desirable and would be unnatural for them.
Acta Orthop. 2010 Jun ;81 (3):337-43 20450422
Huub J Meijerink, Corné J M van Loon, Maarten C de Waal Malefijt, Albert van Kampen, Nico Verdonschot
Department of Orthopaedics, Radboud University Nijmegen Medical Centre, Nijmegen. firstname.lastname@example.org
Ligament releases do not lead to increased postoperative varus-valgus laxity in flexion and extension: a prospective clinical study in 49 TKR patients.
Department of Research, Development and Education, Sint Maartenskliniek, Postbox 9011, 6500 GM, Nijmegen, The Netherlands. email@example.com
This prospective study investigated whether ligament releases necessary during total knee replacement (TKR) led to a higher varus-valgus laxity during intraoperative examination after implantation of the prosthesis and after 6 months. The laxity values of TKR patients were also compared to healthy controls. Varus-valgus laxity was assessed intra- and postoperatively in extension and 70 degrees flexion in 49 patients undergoing TKR, implanted using a balanced gap technique. Knees were catalogued according to ligament releases performed during surgery. Postoperative varus-valgus laxity and laxity after 6 months had not increased following release of the posteromedial capsule, iliotibial tract, and the superficial medial collateral ligament. The obtained postoperative laxity compares well with a healthy equally aged control group. It can be concluded that the balanced gap technique results in stable knees and that releases can safely be performed to achieve neutral leg alignment without causing postoperative laxity.
The relationship of anteroposterior, transepicondylar and posterior condylar axis of the femur: a Thai cadaveric study using digital measurement.
Department of Orthopedics, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand. firstname.lastname@example.org
OBJECTIVE To study the normal relationship of the anteroposterior (AP), transepicondylar (TE) and posterior condylar (PC) axis of cadaveric femoral bones using digital technology and special computer program. MATERIAL AND METHOD Digital image of distal femur of 100 cadaveric bones of both sides and both sexes were taken using a special stand and clamp to ensure the same view and same distance from bone to camera. All still images were transferred into a specially developed computer program, then reference points were located by two observers, and were done twice at one week interval. The program reported the angle between AP-TE, AP-PC and TE-PC axes automatically. The data was then analyzed. RESULTS The age of donor cadaveric bones ranged from 22 to 58 years (average 45.61 +/- 7.73). The AP-TE, AP-PC and TE-PC angles were 92.43 +/- 2.07, 86.65 +/- 1.85 and 5.79 +/- 1.26, respectively. The correlation coefficients of intra-observer reliability in observer 1 were 0.89, 0.87 and 0.91; in observer 2 were 0.92, 0.90 and 0.87. The correlation coefficients of inter-observer reliability were 0.81, 0.82 and 0.80. Limit agreement tests of AP-TE, AP-PC and TE-PC were 90.59%, 92. 57% and 96.03%, in that order. CONCLUSION Using digital technology, the normal relationship of AP, TE and PC axes of femur from cadaveric bone could be more accurately studied comparing with the previous studies performing measurement on plain film, CT scan or MRI using goniometer.
Department of Mechanical Engineering, University of California at Davis, Davis, CA, USA. email@example.com
In general practice, short films of the knee are used to assess component position and define the entry point for intramedullary femoral alignment in TKAs; however, whether it is justified to use the short film commonly used in research settings and everyday practice as a substitute for the whole leg view is controversial and needs clarification. In 138 long leg CT scanograms we measured the angle formed by the anatomic axis of the proximal fourth of the tibia and the mechanical axis of the tibia, the angle formed by the anatomic axis of the distal fourth of the femur and the mechanical axis of the femur, the "bow" of the tibia (as reflected by the offset of the anatomic axis from the center of the talus), and the "bow" of the femur (as reflected by the offset of the anatomic axis from the center of the femoral head). Because the angle formed by these axes and the bow of the tibia and femur have wide variability in females and males, a short film of the knee should not be used in place of the whole leg view when accurate assessment of component position and limb alignment is essential. A previous study of normal limbs found that only 2% of subjects have a neutral hip-knee-ankle axis, which can be explained by the wide variability of the bow in the tibia and femur and the lack of correlation between the bow of the tibia and femur in a given limb as shown in the current study.
Navigation-assisted minimal invasive total knee arthroplasty in patients with extra-articular femoral deformity.
Department of Orthopaedic Surgery, Center for Joint Diseases, Kyung Hee University East-West Neo Medical Center, Seoul, Korea.
In the presence of extra-articular femoral deformity, total knee arthroplasty (TKA) is difficult to perform because of altered anatomical axis and distorted landmarks. Although minimal invasive surgery (MIS) has known advantage of earlier rehabilitation, MIS with this deformity may have higher incidence of component malposition due to inadequate exposure. Navigation has been shown to increase the accuracy of alignment and may compensate possible complication of MIS. We report 4 cases with extra-articular femoral deformity that underwent MIS-TKA using an image-free navigation system in which preoperatively planned mechanical alignment was surgically achieved with proper positioning of the implants as well as soft tissue balance. Navigation-assisted MIS-TKA may become a valuable mean especially for a patient with a deformed femur in which conventional instruments are difficult to use correctly.
Department of Orthopaedic Surgery, UC Davis Medical Center, Sacramento, CA 95817, USA. firstname.lastname@example.org
Analysis of deformity and subsequent correction are the basis for many orthopaedic surgical procedures. In advanced cases of joint degeneration, arthroplasty may be the only available treatment option. Until recently, these analyses and preoperative surgical plans have been performed using standard radiographs, tracing paper, and/or plastic overlays. Numerous customized, commercially available, computer-based preoperative planning software programs have been introduced. The purposes of this study were to describe (1) the techniques used in deformity analysis and preoperative surgical planning using standard radiographs for joint arthroplasty and corrective osteotomies of the extremities,(2) the use of computed tomography (CT) scans to analyze rotational deformities in the presence and absence of joint prostheses and in planning corrective rotational osteotomies or revision joint replacement, and (3) the techniques for analyzing angular deformities of the spine. All these applications were performed with a widely available image analysis software.
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Hollywood Specialist Centre, Suite 8/95 Monash Avenue, Nedlands, Western Australia 6009, Australia. email@example.com
The University of Queensland Department of Surgery, Greenslopes Repatriation Hospital, Greenslopes, QLD 4120, Australia.
It has been proposed that nontraumatic ischemic necrosis of bone (INB) is a result of lipid associated intraosseous thrombosis. A histological study of 15 patients with INB confirmed the presence of intravascular lipid and thrombosis in the vessels of the femoral head. A similar analysis of 11 patients with primary osteoarthritis (OA) showed similar changes at lower levels. These changes were not observed in seven control femoral heads. The possibility that both INB and OA result from intraosseous thrombosis is discussed.
Computer-assisted total knee replacement. A controlled cadaver study using a multi-parameter quantitative CT assessment of alignment (the Perth CT Protocol).
Perth Radiological Clinic and Hollywood Private Hospital, Perth, Western Australia.
A controlled study, comparing computer- and conventional jig-assisted total knee replacement in six cadavers is presented. In order to provide a quantitative assessment of the alignment of the replacements, a CT-based technique which measures seven parameters of alignment has been devised and used. In this a multi-slice CT machine scanned in 2.5 mm slices from the acetabular roof to the dome of the talus with the subject's legs held in a standard position. The mechanical and anatomical axes were identified, from three-dimensional landmarks, in both anteroposterior and lateral planes. The coronal and sagittal alignment of the prosthesis was then measured against the axes. The rotation of the femoral component was measured relative to the transepicondylar axis. The rotation of the tibial component was measured with reference to the posterior tibial condyles and the tibial tuberosity. Coupled femorotibial rotational alignment was assessed by superimposition of the femoral and tibial axial images. The radiation dose was 2.7 mSV. The computer-assisted total knee replacements showed better alignment in rotation and flexion of the femoral component, the posterior slope of the tibial component and in the matching of the femoral and tibial components in rotation. Differences were statistically significant and of a magnitude that support extension of computer assistance to the clinical situation.
Hollywood Private Hospital, Perth, Western Australia.
A technique for performing allograft-augmented revision total knee replacement (TKR) using computer assistance is described, on the basis of the results in 14 patients. Bone deficits were made up with impaction grafting. Femoral grafting was made possible by the construction of a retaining wall or dam which allowed pressurisation and retention of the graft. Tibial grafting used a mixture of corticocancellous and morsellised allograft. The position of the implants was monitored by the computer system and adjusted while the cement was setting. The outcome was determined using a six-parameter, quantitative technique (the Perth CT protocol) which measured the alignment of the prosthesis and provided an objective score. The final outcomes were not perfect with errors being made in femoral rotation and in producing a mismatch between the femoral and tibial components. In spite of the shortcomings the alignments were comparable in accuracy with those after primary TKR. Computer assistance shows considerable promise in producing accurate alignment in revision TKR with bone deficits.
Hollywood Private Hospital, Nedlands, Western Australia.
ANZ J Surg. 2001 Jan ;71 (1):2-3 11167588
Problem Oriented Summary, Audit, Discharge (POSAD) is presented as a system which permits auditing of in-patient admissions. It is prospective, comprehensive, simple to operate and generates an immediate discharge summary. it has replaced the conventional hospital discharge summary and therefore does not increase secretarial or medical workload. It can be run either as a paper-based system or computerized. The work profile and quality control information that has resulted from the 1982 auditing of the Hollywood Orthopaedic Service is presented. This service involves eight consultant orthopaedic staff who dealt with 2,322 hospital patient admissions in that year. Auditing/peer review has shown up wide variations in surgical behaviour and the workload undertaken by individuals. The information that has been produced has enabled the surgeons of this service to put into effect three significant innovations. These are:(a) Regular analysis of complications.(b) Rank ordering (comparison) of individual surgeons.(c) Ready access to current statistics.
Department of Surgery (Orthopaedics), University of Western Australia, Perth, Australia.
BACKGROUND Patients with chronic low back pain present physicians with diagnostic and therapeutic problems. Physical treatments tend to have low success rates and it is postulated that this may be because low back pain can be a manifestation of abnormal illness behaviour. METHODS A structured prospective study determined the prevalence of somatization in a sample of 131 adult patients with chronic low back pain using the Illness Behaviour Questionnaire (IBQ) and the Modified Somatic Perception Questionnaire (MSPQ). The scores on these psychological questionnaires were compared with the blind interpretation of pain distribution drawings and with the results of a mechanical classification of the patient's symptoms and signs. RESULTS Fifty-four per cent of patients had four or more (out of five) abnormal illness indicators. The MSPQ values for the group were significantly above the control values in the literature. Thirty-two per cent of pain diagrams were thought to be incompatible with an organic cause when assessed by an orthopaedic surgeon and sixty-two per cent when assessed by a psychiatrist. CONCLUSIONS Psychosocial factors are dominant in the presentation of chronic low back pain in adults and the disorder is not primarily a musculoskeletal one.
Sir Charles Gairdner Hospital, Nedlands, WA.
OBJECTIVE To describe the Domiciliary Rehabilitation and Support Program (whose principles are early surgery, rapid mobilisation, avoidance of sedation, and early discharge with physiotherapy and nursing support provided in the home) for elderly patients with proximal femoral fractures (PFF), and to compare its costs with those of a conventional approach to the problem. DESIGN AND SETTING Prospective data accumulation on all patients admitted to a major metropolitan teaching hospital (Sir Charles Gairdner Hospital). PATIENTS Six hundred and fifteen patients, 60 years or more, 76% female (mean age 82.6 +/- 8.1 years), 24% male (mean age 79.9 +/- 7.6 years). RESULTS The mean length of hospital stay of patients on the program was 18.9 (+/- 27.3) days compared with 28 days for elderly PFF patients in the preceding year. The morbidity and mortality figures were comparable with or better than other published series. There was a 15% financial saving following introduction of the scheme. CONCLUSION The Domiciliary Rehabilitation and Support Program is a safe and cost effective method of dealing with elderly patients suffering from a proximal femoral fracture.
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University of South Florida College of Medicine, Florida Orthopaedic Institute, 13020 N. Telecom Parkway, Temple Terrace, Florida 33637, USA.
Smart trials are total knee tibial trial liners with load bearing and alignment sensors that will graphically show quantitative compartment load-bearing forces and component track patterns. These values will demonstrate asymmetrical ligament balancing and misalignments with the medial retinaculum temporarily closed. Currently surgeons use feel and visual estimation of imbalance to assess soft-tissue balancing and tracking with the medial retinaculum open, which results in lower medial compartment loads and a wider anteroposterior tibial tracking pattern. The sensor trial will aid the total knee replacement surgeon in performing soft-tissue balancing by providing quantitative visual feedback of changes in forces while performing the releases incrementally. Initial experience using a smart tibial trial is presented.
What is new in female pelvic medicine and reconstructive surgery?: best articles from the past year.
Departments of Obstetrics and Gynecology and Surgery, University of New Mexico Health Sciences Center, Albuquerque, New Mexico.
This month, we focus on current research in female pelvic medicine and reconstructive surgery. Dr. Rogers discusses four recent publications, and each is concluded with a "bottom line" that is the take-home message. The complete reference for each can be found in on this page, along with direct links to the abstracts.
Symptoms of postsurgical distress following total knee replacement and their relationship to recovery outcomes.
Department of Psychology, Kent State University at Stark, N Canton, OH 44720, USA. firstname.lastname@example.org
OBJECTIVE Prior research has suggested that posttraumatic stress symptoms may occur in the context of medical events. Further, these symptoms are often comorbid with conditions associated with pain. Therefore, the current study examined the occurrence of distress following arthroplastic surgery and the relationship of these symptoms to postoperative recovery. METHODS Patients (N =110) undergoing unilateral, total knee replacement (TKR) surgery were assessed at three time points proximal to their surgery: approximately 2 weeks prior to surgery (T1), 1 month following surgery (T2) and 3 months following surgery (T3). Patients completed survey assessments of recovery outcomes (Western Ontario and McMaster Universities Osteoarthritis Index) and distress (The Impact of Event Scale [IES]) following surgery (T2 and T3). RESULTS A significant percentage (20%) of patients undergoing TKR reported noteworthy levels of postsurgical stress 1 and 3 months following surgery. Further, this distress was associated with a more difficult recovery following TKR, characterized by more severe pain and greater functional limitations. After controlling for potential confounding variables, regression analyses suggested that postsurgical stress was cross-sectionally related to pain perception and longitudinally predicted subsequent functional limitations and global assessments of recovery. DISCUSSION To our knowledge, this is the first study to examine postoperative distress (using the IES) following TKR. The present study adds to the growing body of literature documenting the impact of psychological processes on postoperative recovery.
Critical review of the current practice for computer-assisted navigation in total knee replacement surgery: cost-effectiveness and clinical outcome.
Centre for Hip and Knee Surgery, Wrightington Hospital,Wigan, UK. email@example.com
In this article, we present a review of the current practice regarding computer-assisted navigation in total knee replacement together with the bearing on cost-effectiveness and clinical outcome.
Total knee replacement in patients with significant femoral bowing in the coronal plane: a comparison of conventional and computer-assisted surgery in an Asian population.
Chang Gung Memorial Hospital, Chia Yi, Chang Gung University, No. 6, West Section, Chia Pu Road, Puzih, Chia Yi Hsien 613, Taiwan.
We conducted a retrospective study to investigate the effect of femoral bowing on the placement of components in total knee replacement (TKR), with regard to its effect on reestablishing the correct mechanical axis, as we hypothesised that computer-assisted total knee replacement (CAS-TKR) would produce more accurate alignment than conventional TKR. Between January 2006 and December 2009, 212 patients (306 knees) underwent TKR. The conventional TKR was compared with CAS-TKR for accuracy of placement of the components and post-operative alignment, as determined by five radiological measurements. There were significant differences in the reconstructed mechanical axes between the bowed and the non-bowed group after conventional TKR (176.2° (SD 3.4) vs 179.3° (SD 2.1), p < 0.001). For patients with significant femoral bowing, the reconstructed mechanical axes were significantly closer to normal in the CAS group than in the conventional group (179.2° (SD 1.9) vs 176.2° (SD 3.4), p < 0.001). Femoral bowing resulted in inaccuracy when a conventional technique was used. CAS-TKR provides an effective method of restoring the mechanical axis in the presence of significant femoral bowing.
Nurs Stand. ;25 (18):42-5 21309321
Policy Unit, Royal College of Nursing, London. firstname.lastname@example.org
The Patient Reported Outcome Measures (PROMs) Programme, which was implemented by the NHS in 2009, gives prominence to patients' views about their health. Self-reported measures of health are now being sought from all patients before and after four elective procedures--hip and knee replacement surgery, hernia repair and varicose veins surgery. This information will be used to assess changes in health and provides routine information on NHS patients' health outcomes for the first time. The information will be used to identify and reward good performance by providers; help patients to make choices and clinicians to monitor and improve quality; and inform commissioners' decisions about which services to prioritise. The aim of this article is to inform nurses about PROMs and encourage them to engage with it.
Atypical pyoderma gangrenosum following total knee replacement surgery: first report in dermatologic literature.
International Society of Dermatology.
An atypical pyoderma gangrenosum mimicking a post surgical cutaneous and subcutaneous infection is being reported for the first time in international literature after knee replacement surgery with the operation site being the starting point of pyoderma gangrenosum. Orthopedic surgeons and general surgeons should be aware of the existence of this disease and its association with surgical trauma.
Department of Pharmacology, University of Minnesota, Minneapolis, MN 55455-0217, USA. email@example.com
Agonist-selective signaling or ligand-biased signaling of G protein-coupled receptor (GPCR) has become the focus of an increasing number of laboratories. The principle of this concept is that agonist possesses different abilities to activate different signaling pathways. Current review summarizes the observations of agonist-selective signaling of various GPCRs, indicating the significance of agonist-selective signaling in biological processes. In addition, current review also provides an overview on how agonist-selective signaling is initiated. Especially, the relationship between GPCR-G protein interaction and GPCR-beta-arrestin interaction is discussed in depth.
The economic implications of a multimodal analgesic regimen for patients undergoing major orthopedic surgery: a comparative study of direct costs.
Department of Anesthesiology, Mayo Clinic College of Medicine, Rochester, MN, USA.
BACKGROUND AND OBJECTIVES Total knee and total hip arthoplasty (THA) are 2 of the most common surgical procedures performed in the United States and represent the greatest single Medicare procedural expenditure. This study was designed to evaluate the economic impact of implementing a multimodal analgesic regimen (Total Joint Regional Anesthesia [TJRA] Clinical Pathway) on the estimated direct medical costs of patients undergoing lower extremity joint replacement surgery. METHODS An economic cost comparison was performed on Mayo Clinic patients (n = 100) undergoing traditional total knee or total hip arthroplasty using the TJRA Clinical Pathway. Study patients were matched 1:1 with historical controls undergoing similar procedures using traditional anesthetic (non-TJRA) techniques. Matching criteria included age, sex, surgeon, type of procedure, and American Society of Anesthesiologists (ASA) physical status (PS) classification. Hospital-based direct costs were collected for each patient and analyzed in standardized inflation-adjusted constant dollars using cost-to-charge ratios, wage indexes, and physician services valued using Medicare reimbursement rates. The estimated mean direct hospital costs were compared between groups, and a subgroup analysis was performed based on ASA PS classification. RESULTS The estimated mean direct hospital costs were significantly reduced among TJRA patients when compared with controls (cost difference, 1999 dollars; 95% confidence interval, 584-3231 dollars; P = 0.0004). A significant reduction in hospital-based (Medicare Part A) costs accounted for the majority of the total cost savings. CONCLUSIONS Use of a comprehensive, multimodal analgesic regimen (TJRA Clinical Pathway) in patients undergoing lower extremity joint replacement surgery provides a significant reduction in the estimated total direct medical costs. The reduction in mean cost is primarily associated with lower hospital-based (Medicare Part A) costs, with the greatest overall cost difference appearing among patients with significant comorbidities (ASA PS III-IV patients).
Int Orthop. 2010 Jun ;34 (5):655-62 19513711
1st Orthopedic Department, CTO Hospital, Via Bignami 1, 20100, Milan, Italy. firstname.lastname@example.org
Computer-assisted total knee replacement (TKR) has been shown to improve radiographic alignment. Continuous feedback from the navigation system allows accurate adjustment of the bone cuts, thus reducing errors. The aim of this study was to determine the impact of experience both with computer navigation and knee replacement surgery on the frequency of errors in intraoperative bone cuts and implant alignment. Three homogeneous patient groups undergoing computer assisted TKR were included in the study. Each group was treated by one of three surgeons with varying experience in computer-aided and knee replacement surgery. Surgeon A had extensive experience in knee replacement and computer-assisted surgery. Surgeon B was an experienced knee replacement surgeon. A general orthopaedic surgeon with limited knee replacement surgery experience performed all surgeries in group C. The cutting errors and the number of re-cuts were determined intraoperatively. The complications and mean surgical time were collected for each group. The postoperative frontal femoral component angle, frontal tibial component angle, hip-knee-ankle angle and component slopes were evaluated. The results showed that the number of cutting errors were lowest for TKR performed by the surgeon with experience in navigation. This difference was statistically significant when compared to the general orthopaedic surgeon. A statistically significant superior result was achieved in final mechanical axis alignment for the surgeon experienced in computer-guided surgery compared to the other two groups (179.3 degrees compared to 178.9 degrees and 178.1 degrees ). However, the total number of outliers was similar, with no statistically significant differences among the three surgeons. Experience with navigation significantly reduced the surgical time.