A Novel Design of a Metacarpal/MetatarsaI-Phalangeal Total Joint Replacement

Arthritis, most notably rheumatoid arthritis, can destroy the surfaces of the bones; the ideal solution for this is T JR （total joint replacement）, which would restore joint functionality, maintain correct aesthetics and eradicate pain for the patient. Current metacarpophalangeal TJR do not provide the normal biomechanical range of motion and functionality. The proposed design attempts to correct this through the use of design geometry and functional anatomy. Numerical analysis is used in conjunction with computational solid modeling to compare a one-piece silicone implant with the proposed T JR. Peak stresses during flexion for the proposed design did not exceed 1.2 MPa, where as soft implants approach 100 MPa to 1,000 MPa for peak stress values. The proposed design, due to high stress tolerances with low deformation, along with functionality and biomechanics, seems to be an appropriate replacement for one-piece silicone implant.

Early diagnosis and treatment of pulmonary embolism after total joint replacement: report of five cases

Objective To study the early diagnosis and treatment of pulmonary embolism (PE) after total joint replacement (TJR). Methods From April 1987 to December 2001, we performed 1 336 total knee replacements (TKR) in 926 patients and 1 745 total hip replacements (RHRs) in 1 566 patients. In this group there were 5 PE patients after operation. Two patients died (all after TKR), and 3 patients salvaged successfully (2 after TKR, 1 after THR). Results The total incidence of PE after TJR was 0. 2% (5/2 492), the incidence of PE after TKR was 0. 4% (4/926), and the incidence of PE after THR was 0.06% (1/1 556). In the patients who suffered PE, 2 died. The incidence of PE before 2000 was 0%. Conclusion Death after total joint replacement is due to pulmonary embolism ( PE), especially massive PE. The incidence of PE after TKR is higher than that after THR. Pulmonary angiography is the gold standard for the diagnosis of PE. With more understanding on PE and more popularity of joint replacement, the diagnosis of PE

Knowledge and attitudes of orthopedic surgeons regarding prosthesis joint infection

BACKGROUND Periprosthetic joint infection(PJI)is a critical complication after joint arthroplasty and is accompanied by increasing rates of morbidity and mortality.Several studies have aimed at preventing PJI.AIM To research the knowledge level and attitudes of orthopedic surgeons,who play a key role in both preventing and managing PJI.METHODS We conducted a web-based survey to evaluate orthopedic surgeons'knowledge level and attitudes regarding PJI.The Likert scale survey utilized consisted of 30 questions which were prepared based on the"Proceedings of the International Consensus on Periprosthetic Joint Infection".RESULTS A total of 264 surgeons participated in the survey.Their average age was 44.8,and 173 participants(65.5%)had more than 10 years of experience.No statistically significant relationship was found between the PJI knowledge of the surgeons and their years of experience.However,participants who worked in training and research hospitals demonstrated higher levels of knowledge than the ones in the state hospitals.It was also noticed that surgeons'knowledge concerning the duration of antibiotic therapy and urinary infections was not consistent with their attitudes.CONCLUSION Even though orthopedic surgeons have adequate knowledge about preventing and managing PJI,their attitudes might contradict their knowledge.Future studies are required to examine the causes and solutions of the contradictions between orthopedic surgeons'knowledge and attitudes.

ANALYSIS AND RESEARCH OF COMPUTER-AIDED MODEL OF HIP JOINT BASED ON REVERSE ENGINEERING

Former research work about the modeling of hip joint focus on the uppersegment of femoral, and assumes the acetabulum cup is sphere concave, and the acetabulum prosthesesis semisphere. A method of acquiring the point data on the surface of the hipbone using the reverseengineering technology is presented. After analyzing the acetabulum surface fitting error, arotation ellipsoid CAD model is applied to fit the acetabulum surface, and then optimizationtechnique is used to find the geometric parameters of the model. The fitting error between thesphere and rotation ellipsoid is compared and gets the result that the fitting error of rotationellipsoid is smaller than sphere, and the rotation ellipsoid can describe the shape of theacetabulum better.

Rural implementation of the perioperative surgical home:A case-control study

BACKGROUND Perioperative surgical home(PSH)is a novel patient-centric surgical system developed by American Society of Anesthesiologist to improve outcomes and patient satisfaction.PSH has proven success in large urban health centers by reducing surgery cancellation,operating room time,length of stay(LOS),and readmission rates.Yet,only limited studies have assessed the impact of PSH on surgical outcomes in rural areas.AIM To evaluate the newly implemented PSH system at a community hospital by comparing the surgical outcomes using a longitudinal case-control study.METHODS The research study was conducted at an 83-bed,licensed level-III trauma rural community hospital.A total of 3096 TJR procedures were collected retrospectively between January 2016 and December 2021 and were categorized as PSH and non-PSH cohorts(n=2305).To evaluate the importance of PSH in the rural surgical system,a case-control study was performed to compare TJR surgical outcomes(LOS,discharge disposition,and 90-d readmission)of the PSH cohort against two control cohorts[Control-1 PSH(C1-PSH)(n=1413)and Control-2 PSH(C2-PSH)(n=892)].Statistical tests including Chi-square test or Fischer’s exact test were performed for categorical variables and Mann-Whitney test or Student’s t-test were performed for continuous variables.The general linear models(Poisson regression and binomial logistic regression)were performed to fit adjusted models.RESULTS The LOS was significantly shorter in PSH cohort compared to two control cohorts(median PSH=34 h,C1-PSH=53 h,C2-PSH=35 h)(P value<0.05).Similarly,the PSH cohort had lower percentages of discharges to other facilities(PSH=3.5%,C1-PSH=15.5%,C2-PSH=6.7%)(P value<0.05).There was no statistical difference observed in 90-d readmission between control and PSH cohorts.However,the PSH implementation reduced the 90-d readmission percentage(PSH=4.7%,C1-PSH=6.1%,C2-PSH=3.6%)lower than the national average 30-d readmission percentage which is 5.5%.The PSH system was effectively established at the rural community hospital with the help of team-based coordinated multi-disciplinary clinicians or physician comanagement.The elements of PSH including preoperative assessment,patient education and optimization,and longitudinal digital engagement were vital for improving the TJR surgical outcomes at the community hospital.CONCLUSION Implementation of the PSH system in a rural community hospital reduced LOS,increased directto-home discharge,and reduced 90-d readmission percentages.

Current concept in first metatarsophalangeal joint replacement

First metatarsophalangeal joint （MTPJ） degenerative diseases are not rare pathological changes in adult forefoot.1,2 It mainly includes hallux rigidus,hallux limitus and hallux valgus.3 Its progressive nature makes it hardly respond well to conservative treatment.4 Traditional surgical techniques,such as cheilectomy,Keller resection and arthrodesis are effective procedures but remain controversial due to none of them can achieve excellent results in all patients especially the end-stage conditions.5-7 Thus,great amount of efforts have been dedicated in MTPJ replacement despite many negative reports.This technique has aroused many controversies over the past decades due to its prematurity.Nevertheless,it has been improved in many aspects such as prosthesis material,design as well as surgical indications.This review would not only update the advancements and recognitions in recent years,but also presented the major disputed areas.

Tribological Performance of Bioimplants: A Comprehensive Review

Total joint replacements(TJR) have been a huge success for orthopaedic surgery in the past century and are gaining increasing importance today due to the aging population. However, the short longevity of artificial joints is one of the major problems in bioimplant industry and needs to be rectified since an increasing number of young people, with more active lifestyles, must receive TJR. Wear mechanisms are discussed in this paper to describe the root causes of the failures and to give some general ideas to increase the lifespan of artificial joints. The suitable material combination is of great importance for the wear resistance of bioimplants, and bioceramics will exert a crucial effect in their future progress. Other materials, such as metal alloys and polymers, are also discussed in this paper. Surface finish is another factor affecting the tribological performance of bioimplants. In recent years, surface texture technology has fascinated many researchers, and a good design of texture pattern requires a comprehensive understanding of wear mechanisms, material properties, and dynamic fluid theory. This review also covers a summary of in vitro wear tests, including simulators, lubricant, and testing parameters.

DEXA overestimates bone mineral density in adults with knee replacements

We examined bone mineral density(BMD)measurements made by dual-energy-xray-absorptiometry(DEXA)taken from 100 patients(♂46/♀54,66±6yr)who previously underwent single total-knee arthroplasty(TKA)to determine if automated software-based artifact detection(ASAD)adequately removes implant artifact from the DXA image before analysis and if potential inaccuracies could be overcome through manual artifact correction(MAC).We also sought to determine if software-based inaccuracies would result in fracture risk misclassification(Low-BMD/Osteopenia=Young-Adult T-Score<−1).Select Results:When using ASAD,limbs with implants had higher BMD(+12.0±1.7%,p<0.001)compared to control limbs resulting in a 2.5±0.2%overestimation of total-body BMD(single implant).Consequently,the prevalence of osteopenia in 95%of patients who would have been observed to have low leg BMD(18/19 patients)and 80%of those found to have low total-body BMD(4/5 patients)would have gone un-diagnosed.This overestimation was eliminated when using MAC.These results reveal a potential issue with ASAD for total-body DEXA scans in TKA patients and highlight the importance of careful review and MAC in those with joint replacements before making diagnostic decisions.

Macrophage polarization in response to wear particles in vitro

Total joint replacement is a highly successful surgical procedure for treatment of patients with disabling arthritis and joint dysfunction. However, over time, with high levels of activity and usage of the joint, implant wear particles are generated from the articulating surfaces. These wear particles can lead to activation of an inflammatory reaction, and subsequent bone resorption around the implant （periprosthetic osteolysis）. Cells of the monocyte/macrophage lineage orchestrate this chronic inflammatory response, which is dominated by a pro-inflammatory （M 1） macrophage phenotype rather than an anti-inflammatory pro-tissue healing （M2） macrophage phenotype. While it has been shown that interleukin-4 （IL-4） selectively polarizes macrophages towards an M2 anti-inflammatory phenotype which promotes bone healing, rather than inflammation, little is known about the time course in which this occurs or conditions in which repolarization through I L-4 is most effective. The goal of this work was to study the time course of murine macrophage polarization and cytokine release in response to challenge with combinations of polymethyl methacrylate （PMMA） particles, lipopolysaccharide （LPS） and IL-4 in vitro. Treatment of particle-challenged monocyte/macrophages with IL-4 led to an initial suppression of pro-inflammatory cytokines and inducible nitric oxide synthase （iNOS） production and subsequent polarization into an M2 anti-inflammatory phenotype. This result was optimized when IL-4 was delivered before PMMA particle challenge, to an M 1 phenotype rather than to uncommitted （MO） macrophages. The effects of this polarization were sustained over a 5-day time course. Polarization of M1 macrophages into an M2 phenotype may be a strategy to mitigate wear particle associated periprosthetic osteolysis.