The Influence Of Limb Alignment On The Progress Of Lateral Compartment Osteoarthritis After Oxford Unicompartmental Knee Arthroplasty

ObjectiveUnicompartmental knee arthroplasty(UKA)is one of the main methods for the treatment of knee osteoarthritis at present.The long-term follow-up studies of unicompartmental knee arthroplasty have shown that the progression of lateral compartment osteoarthritis is one of the main reasons for the revision after UKA,and the limb alignment is considered to be an important factor leading to the progression of lateral compartment osteoarthritis after UKA.The purpose of this study is to find out the location of limb alignment to prevent the progression of lateral compartment osteoarthritis after Oxford unicompartmental knee arthroplasty by comparing the medium-and short-term follow-up results of patients with and without progression of osteoarthritis in the lateral compartment of Oxford UKA,such as the clinical function,the progress of lateral compartment osteoarthritis during the follow-up and the difference of the limb alignment after the operation between the two groups of patients.MethodsFrom December 2014 to December 2017,a retrospective analysis was made on the data of patients who underwent Oxford unicompartmental knee arthroplasty in the Guangdong Provincial Hospital of Traditional Chinese Medicine and were followed up for at least two years.A total of 100 patients met the inclusion criteria and exclusion criteria.According to the Kellgren-Lawrence X-ray classification(KL classification),patients with progressive lateral compartment osteoarthritis and lateral knee pain during the follow-up were included in the progressive group,and patients with no change or improvement of the lateral compartment osteoarthritis were included in the non-progressive group during follow-up.Patients in both groups were treated with Oxford phase III mobile-bearing unicondylar knee prosthesis.There are 50 cases(50 knees)in the progressive group,including 14 males and 36 females,with an average age of 66.38 years(53-80 years),and 50 cases(50 knees)in the non-progressive group,14 males and 36 females,with an average age of 64.24 years(51-78 years).All patients were treated with minimally invasive UKA incision technique,and bone cement was used to fix the prosthesis during the operation.The general data such as name,age,sex,height,weight,body mass index(BMI),operation time,intraoperative blood loss,and hospitalization days of the two groups were recorded respectively.The anteroposterior X-ray and bilateral lower extremity negative-position X-ray of both legs were performed before the operation,after the operation and during the last follow-up.The hip-knee-ankle angle(HKA)before the operation and after the operation and the tibial plateau region through the mechanical axis of lower extremity after the operation were measured.The hospital for Special Surgery knee knee score(HSS score),VAS score,the straightening angle and flexion angle of knee were assessed and measurement before the operation and at the last follow-up.The clinical and imaging results were compared between the two groups before operation and the last follow-up.SPSS 25.0 software was used for data processing and statistical analysis(P<0.05 was considered statistically significant).ResultsThere was no significant difference in preoperative general data(sex,age,height,weight,BMI,operation time,intraoperative blood loss,and hospitalization days)between the two groups.All the incisions were primary healing after operation.All patients had no blood transfusion in the perioperative period.There were no complications such as aseptic prosthesis loosening,unexplained pain of knee,insert dislocation,periprosthetic fractures,pulmonary embolism,deep venous thrombosis,infection,poor wound healing and so on.Compared the result between preoperative and the last follow-up,there are significant differences in HSS score,VAS score,straightening angle and flexion angle of knee between the two groups(P<0.05).The differences of HSS score and VAS score at the last follow-up between the two groups is statistically significant(P<0.05).The difference of knee straightening angle and flexion angle between the two groups at the last follow-up is not statistically significant(P>0.05).In terms of imaging,there is no significant difference in preoperative KL classification and HKA between two group(P>0.05),but there is significant difference in KL classification at the last follow-up and HKA after the operation between the two groups(P<0.05).There is significant difference in the number of tibial plateau region through the mechanical axis of the lower extremities between two groups at the last follow-up(P<0.05).In the non-progressive group,the postoperative limb alignment was neutral,while in the progressive group,the postoperative limb alignment was valgus.ConclusionAt the last follow-up,the degree of pain and the function of knee in the non-progressive group are better than those in the progressive group,but there is no significant difference in the range of motion of the knee between the two groups.The postoperative limb alignment of neutral position may play a good role in preventing the progression of lateral compartment osteoarthritis after Oxford UKA,while the postoperative limb alignment of partial valgus may be related to the progression of lateral compartment osteoarthritis after Oxford UKA.Limb alignment is one of the predictors of the progression of lateral compartment osteoarthritis.