Efficacy Evaluation And Failure Mechanisms Of The Unicompartmental Knee Arthroplasty

Background:With the increasing of obesity people and the aging of the population,the incidence of osteoarthritis of the knee is improving year by year.The unicompartmental knee arthroplasty(UKA)has drawn many joint surgeons'attention because of its effective treatment for the unicompartmental osteoarthritis.Methods:A total of 118 patients(126 knees)were underwent UKA in our hospital from March 2010 to December 2014.We followed up these patients to obtain the OKS,HSS,SF-36 score and X-ray pre-and post-operation.We measured FTA angle to evaluate the alignment and compared the scores to evaluate the efficacy of UKA surgery.All cases were grouped according to gender,age,BMI and some other factors,in order to explore the factors affecting the effect of surgery.The failure mechanism was analyzed by recording all the complications and failure of the revision.Purpose:Our hospital has also carried out UKA surgery in recent years,but we don't know its'efficacy.So this project aims to research the efficacy of UKA in our hospital,and explore factors influencing the surgery outcome.In addition to this,we also want to analyze the failure cases to realize the failure mechanisms of UKA.Results:72 patients(77 knees)were analyzed,including 14 men(15 knees)and 58women(62 knees).They are between 44 to 82 years old,average 63.5±8.2.The BMI is between 19.5 to 34.2,average 25.7±3.4 kg/m~2.The median scoring of OKS is 24pre-operation and 39 post-operation.The median scoring of HSS is 69 pre-operation and 89 post-operation.The SF-36 scoring post-operation are better in all the 8 aspects than pre-operation.The FTA angle pre-and post-operation are 181°and 178°.Dividing these cases into different groups by age,gender,BMI and doctors,the OKS scorings between groups indicate no significant difference.We have 6 cases requiring revision,revision rate is 7.8%,the five-year survival is 81.3%.Given the patients losing follow up have low probability to revise,the five-year survival may improve to91.0%.The mechanisms for revision are dislocation of the bearing,unexplained pain and aseptic loosening.Conclusion:UKA surgery can obtain a good knee function,significantly relieve pain,and improve quality of life.The factors influencing the surgery efficacy mainly include three aspects,patient factors,surgeon factors and technique factors.There is no consensus about how do patients'age and BMI influence the surgery efficacy.Most scholars agree that the lateral compartment osteoarthritis and patellofemoral arthritis does not affect the surgical outcome.UKA has a higher revision rate than TKA,but the interpretation about this fact is not consistent.The mainly mechanisms for revision include aseptic loosening,progression of the lateral compartmental arthritis.