Comparison Of Alignment Correction And Clinical Outcomes Between Fixed-bearing And Mobile-bearing UKA

ObjectiveUnicompartmental knee arthroplasty(UKA)has become one of the effective ways to treat osteoarthritis of the knee joint compartment.There are two kinds of unicompartmental prosthesis,which are mobile-bearing and fixed-bearing prosthesis.In theory,mobile-bearing prosthesis is more suitable for human biomechanics and better curative effect than fixed-bearing prosthesis,but the conclusion of clinical report is not consistent.In this study,we compare the differences between the fixed-bearing and mobile-bearing prosthesis in the treatment of knee medial compartment osteoarthritis in relieving knee pain,reconstructing knee function and correcting the line of knee lower limb,and provide basis for better clinical selection of prosthesis.MethodsThe data of patients who underwent unicompartmental knee arthroplasty in the Department of Arthiology of Guangdong Provincial Hospital of Traditional Chinese Medicine between January 2013 and December 2017 were retrospectively analyzed.There were 95 patients who met the inclusion and exclusion criteria.According to the differences of the prosthesis.They were setted into MB group and FB group.The mobile-bearing unicompartmental knee prosthesis was Oxford phase ?.The fixed-bearing unicondylar knee prosthesis was LINK? Endo-Model? Sled.There were 48 patients(52 knees)in MB group,while 34 patients were male and 14 female,with a average age of 66.52 years(range,50~83 years).There were 47 patients(54 knees)in FB group,36 males and 11 female.and the average age was 69.38 years(range,48~88 years).All the cases were completed by the same chief surgeon.Minimally invasive UKA incision technique was used.All the patients were fixed with bone cement.The patient's gender,age,weight,body mass index(BMI),operation time,intraoperative blood loss and other general information were recorded.The anteroposterior X-ray and bilateral lower extremity negative-position X-ray were performed before and after operation.The preoperative and postoperative femoratibial angles(FTA),hip-knee-ankle angle(HKA),tibial angle of inclination(PSA),angle of articular surface of knee joint ?,Rom of knee joint and the change in the height of the joint line were measured,And recorded the zone of the tibial plateau region passed by the mechanical axis of the lower extremities.And evaluate preoperative and last follow-up American Knee Society score(American knee society knee score,referred KSS score),Hospital for Special Surgery knee knee score(hospital for special surgery knee score,referred to as HSS score)score and VAS score.Clinical and radiographic follow-up was done inpreoper-ative and postoperative.We use SPSS 20.0 software for data processing and statistical analysis(P<0.05 was considered statistically significant).Resultsthe characteristics of patients were not statistically significantly different between the two groups.All patients underwent a grade-a wound healing.All patients had no blood transfusion,and no infection,pulmonary embolism,deep venous thrombosis of lower limbs,fracture around prosthesis,aseptic prosthesis loosening,unexplained pain,polyethylene gasket dislocattion and other complications appeared.The mean of KSS score,HSS score,VAS score,Rom of knee joint between MB group and FB group were similar(P>0.05),but they were different between inpreoperative and postoperative(P<0.05).There was no significant difference between the two groups in the HKA,FTA and the change of the height of the articular line(P > 0.05).Differences in preoperative and postoperative HKA and FTA between the MB and FB groups were statistically significant(P<0.05).There were significant differences in the included angle of knee articular surface between MB group and FB group(P<0.05).At the same time,there was no significant correlation between medial compartmental joint line elevation and FTA correction in all patients in the MB group and FB group,while the correlation between medial compartmental joint line elevation and the postoperative HSS score was no significant as well.There was no significant difference in the number of tibial plateau region through the mechanical axis of the lower extremities between MB group and FB group(P>0.05).ConclusionUnder the premise of strictly mastering the indications,regardless of the choice of fixed-bearing and mobile-bearing prosthesis,UKA can effectively relieve the pain and improve the knee function in the treatment of osteoarthritis of the knee joint.In early and mid-term follow-up,there was no significant difference between KSS,HSS score,pain level and ROM of knee between fixed-bearing and mobile-bearing UKA prosthesis.However,the angle of the lower limbs line of the mobile-bearing prosthesis is often larger than that of the fixed-bearing.The mobile bearing is easier to achieve with obtain the neutral or slightly valgus lower limb force line,and the anatomical axis is easier to recover.Therefore,the mobile bearing unicompartmental prosthesis is more advantageous for recovering the lower limb force line.