| BackgroundKnee osteoarthritis(KOA)is a common and frequently-occurring degenerative joint disease among middle-aged and elderly people.In recent years,With the rapid aging of the population,the incidence of KOA in the elderly is increasing year by year.As a chronic disease,it will gradually destroy the knee cartilage and subchondral bone,and lead to bone hyperplasia and rough articular surface eventually,which will affect joint function.The symptoms of patients are pain,swelling and limited activity and the serious cases will appear joint deformity and lower limb force line changes,affecting the quality of life of patients seriously.Now,KOA has became one of the main causes of disability in the elderly.How to effectively treat KOA,relieve the symptoms of patients and improve the quality of life of patients is a difficult problem that sports medicine is committed to conquer.The main treatment method for end-stage KOA is knee arthroplasty.The traditional knee arthroplasty is total knee arthroplasty(TKA),which is to replace all compartments of the knee joint.However,later studies found that most KOA are isolated medial compartment osteoarthritis.This discovery leads to the emergence of unicompartmental knee arthroplasty(UKA),which only replace the affected side of the knee compartment.UKA can not only relieve patients’ symptoms like TKA,but also has the characteristics of minimally invasive surgery,less intraoperative bleeding,less postoperative complications,faster recovery and better motor function compared with TKA.However,due to the small surgical field of UKA and the high surgical technical requirements of the surgeon,there are often deviations in the placement of UKA components.Although there are many researches on the effect of this deviation on the prognosis of patients,much controversy still exists.Since the femoral component in the Oxford mobile-bearing UKA is spherical and has a large tolerance range,our researches mainly focus on the tibial component.ObjectiveTo observe the surgical effect of medial Oxford mobile-bearing UKA on patients,and to explore the effect of tibial component placement on patients’ prognosis during medium length follow-up.MethodsWe collected data of patients who underwent medial Oxford phase III mobile-bearing UKA due to KOA and met the criteria of inclusion and exclusion.Those patients were admitted to Joint Department of Tangdu Hospital,Air Force Military Medical University from 2012 to 2020.A total of 103 patients(105 knees)were included,of which 11 patients were lost to follow-up(13 knees)and 92 patients were included(92 knees).The mean age of operation of patients was 63±5.3 years(47-75 years).There were 51 females(55.4%)and41 males(44.6%),with a mean BMI of 26.3±2.3(21.7-35.9)and 43 patients(46.7%)in the left knee and 49 patients(53.3%)in the right knee.The mean follow-up time of patients was56.5±15.7 months(27-93 months).The evaluation criteria used were Oxford Knee Score(OKS),The American Knee Society(AKS),Visual Analogue Scale(VAS)and Range of patients Motion(ROM)and Hip-knee-ankle angle(HKA).To observe the surgical effect of UKA,we conducted a self-control before and after surgery,and divided the data of each patient into three groups: preoperative,postoperative and last follow-up.Component survival was calculated at the last follow-up.Then appropriate statistical methods were used to compare the evaluation criteria of knee joint among the groups.In order to explore the influence of tibial component position on the prognosis of patients after UKA surgery,our researches will be divided into four aspects: the influence of polyethylene bearing thickness on the prognosis of patients,the influence of tibial resection depth on the prognosis of patients,the influence of tibial alignments of varus and valgus on the prognosis of patients,and the influence of posterior slope of tibial on the prognosis of patients.For each aspect of the study,patients were divided into three groups.First,the baseline data and preoperative knee evaluation criteria data were compared among the groups to ensure the reliability of the grouping.Then,the improvement of the knee evaluation criteria at the last follow-up of the patients was compared and the differences between the groups were determined.Finally,determined whether the correlation was relevant and the degree of correlation.ResultsThe component survival rate of patients at the last follow-up was 97.8%.The OKS increased from 25(19,25)to 41(37,47),with statistical significance(P<0.05),and was 40(38,45)at the last follow-up,with statistical significance compared with that before surgery(P<0.05).AKS-K(The American Knee Society Knee Score)and AKS-F(The American Knee Society Function Score)varied from preoperative scores of 50(40,57)and 73(63,78)increased to 84.5(78,91.25)and 79.5(74,86.25)after operation,which has statistically significant difference(P<0.05).In the meantime,the AKS-K and AKS-F scores were 81(74,89)and 76(73,83)at the last follow-up respectively,which were statistically different from those before surgery(P<0.05).The results of the study on the influence of polyethylene bearing thickness on the prognosis of patients showed that the HKA improvement last follow-up was 3.5(2,5)in the3 mm group,4(3,5.8)in the 4mm group,and 6(5,8)in the ≥5mm group.There were significant differences among the three groups(P<0.05),and the significant differences were between the ≥5mm group and the 3mm group.There were no significant differences among other postoperative knee evaluation criteria last follow-up(P>0.05).In terms of correlation,HKA improvement last follow-up was also significantly correlated with the thickness of polyethylene bearing(P<0.05),and it was moderately correlated(R=0.427).The results of the effect of tibial resection depth on the prognosis of patients showed that: At the last follow-up,HKA improvement was 6(4.3,6)in the ≤6.2mm group,4(2,5)in the 6.2mm to 7.2mm group,and 3(2,5)in the ≥7.2mm group.There were significant differences among groups(P<0.05,and the significant differences were that both 6.2-7.2mm group and ≥7.2mm group were significantly increased compared with ≤6.2mm group.There were no significant differences among other knee evaluation criteria(P>0.05).In terms of correlation,HKA improvement was also significantly correlated with tibial osteotomy volume(P<0.05),indicating a slight correlation(R=0.295).The results of the study on the influence of tibial component alignments of varus and valgus on the prognosis of patients showed that there were no significant differences between groups in the evaluation criteria of postoperative knee joint in groups ≤-3.9°,-3.8°--0.7°,and ≥-0.6° at the last follow-up(P>0.05).The results of studying the effect of posterior slope of tibial component on the prognosis of patients showed that: while the difference in ROM improvement among the ≤5.1°,5.1-3.8° and ≥8.5° groups at the last follow-up wasn’t significant,there was a significant difference in maximum ROM flexion improvement among the three groups(P<0.05),which was a significant difference between the ≥8.5° and ≤5.1° groups.There were no significant differences among other postoperative knee evaluation criteria(P>0.05).In terms of correlation,the improvement of maximum ROM flexion was also significantly correlated with the posterior slope of tibial component(P<0.05),which was a slight correlation(R=0.211).Conclusion1.Comparison of knee scores before,after,and at last follow-up showed that UKA,as a surgical treatment for end-stage KOA,not only significantly improved symptoms and function after surgery in the long term,but also had excellent survival rate of component at medium length follow-up.2.In the study of the influence of polyethylene bearing thickness on the prognosis of patients,the results showed that thicker bearing could significantly increase the HKA reconstruction of patients by comparing the improvement of various knee evaluation criteria in UKA patients at last follow-up,and this improvement was moderately correlated with the thickness of polyethylene bearing.3.By comparing the improvement of knee joint evaluation criteria in patients with different amounts of patients at the last follow-up,we found that the volume of tibial resection was slightly correlated with the improvement of postoperative HKA in,and reducing the volume of tibial resection could significantly improve the angle of postoperative HKA reconstruction.4.In the study of tibial component alignments of varus and valgus in the coronal position,we found that if component alignments of tibial was within a certain range(),there had no significant effect on patients’ symptoms and functional improvement during a medium length follow-up.5.By comparing the differences among the knee evaluation criteria of patients with different posterior slope of tibial component at the last follow-up,we found that although the tibial component posterior slope had no significant effect on the overall ROM improvement at postoperative,increasing the tibial component posterior slope could significantly improve the maximum knee flexion angle of patients,and the both of them presented a slightly correlated trend. |
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