The Relationship Between The Shape Of The Femoral Condyle And The Gap Of Flexion And Extension In Knee Arthroplasty

Objective:To study the relationship between the shape of femoral condyle and the gap of flexion and extension after total knee arthroplasty(TKA)by standard osteotomy.Methods:A total of 76 patientswho underwent knee arthroplasty in our department from September 2015 to September 2016 were enrolled in this study.The anteroposterior diameter to medial-lateral diameter of the femoral condyle were measured according to the preoperative knee X-ray radiographs,25 cases patients which the ratio of the anteroposterior diameter to medial-lateral diameter of the femoral condyle was more than 0.9 were in the group A,42 cases patients which the ratio was in 0.7-0.9 were in the group B,and 9 cases patients with the ratio less than 0.7 were group C,and the flexion gap and extension gap were measured in the total knee arthroplasty(TKA)after standard osteotomy.The knee society score(KSS)and the knee joint range of motion(ROM)were measured among the three groups in the preoperative and postoperative.The flexion gap and extension gap were compared among the three groups in the total knee arthroplasty(TKA).The knee society score(KSS)and the knee joint range of motion(ROM)were compared among the three groups in the preoperative and postoperative.Results:All patients were followed up with an average follow-up of 8 months.There were no complications such as important vascular nerve injury,joint infection,prosthesis loosening,joint instability,periprosthetic fracture and other complications after operation.There were significant difference in the ratio of anteroposterior diameter to medial-lateral diameter of the femoral condyle between the A group and the C group in the preoperative and postoperative(P < 0.05),and there were significant difference in the flexion gap and extension gap between the A group and the C group after standard osteotomy(P < 0.05).There was no significant difference in the ratio of anteroposterior diameter to medial-lateral diameter of the femoral condyle between the B group in the preoperative and postoperative(P>0.05),and there were no significant difference in the flexion gap and extension gap between the B group after standard osteotomy(P > 0.05),and there were no significant differences of the three groups in the ratio of anteroposterior diameter to medial-lateral diameter of the femoral condyle after the operation(P>0.05).The results show that the size of the ratio of anteroposterior diameter to medial-lateral diameter of the femoral condyle is related to the gap of flexion and extension after the operation of the standard osteotomy,and when the ratio of anteroposterior diameter to medial-lateral diameter of the femoral condyle is larger,the flexion gap will be more than extension gap,and when the ratio is smaller,the extension gap will be more than flexion gap.There were no statistically significant difference in the KSS scores and the knee joint range of motion(ROM)of the Preoperative and 6 months after the operation among the three groups(P>0.05).Postoperative improvements of the KSS scores and knee ROM degree were achieved in all groups.Conclusions:1.Patients whose the ratio of anteroposterior diameter to medial-lateral diameter of the femoral condyle is larger,the flexion gap will be more than extension gap after the standard osteotomy in the total knee arthroplasty(TKA),and then will lead to the instability of the knee joint,but we can increase the size of femoral prosthesis or increase the osteotomy of the distal femur during the operation.2.Patients whose the ratio of anteroposterior diameter to medial-lateral diameter of the femoral condyle is smaller,the extension gap will be more than flexion gap after the standard osteotomy in the total knee arthroplasty(TKA),and then we can reduce the size of femoral prosthesis,release the joint capsule and posterior cruciate ligament,and appropriately reduce the distal femur osteotomy.3.The condyle of the femur is abnormal.So when the flexion and extension space is unequal after the standard osteotomy,but the knee function bacomes better after intraoperative adjustment.