Study On The Changes Of Bone Mineral Density Around The Prosthesis Within One Year After Unicompartmental Knee Arthroplasty

ObjectiveTo observe and analyze the change trend and change rate of bone mineral density(BMD)around the prosthesis within one year after unicompartmental knee arthroplasty(UKA)in patients with knee osteoarthritis,and to summarize the changes.Based on these results,it is speculated whether the need for bone protection and its optimal timing after UKA in China will provide guidance for patients with reasonable and effective anti-osteoporosis after UKA in China.MethodsThrough longitudinal study,randomly selected 31 patients from the inpatient department of the Orthopedics of Guangdong Provincial Hospital of Traditional Chinese Medicine from February 2018 to April 2018 to treat medial compartment knee osteoarthritis.Before the operation,the patients at the 3rd,6th,and 12th postoperative month were treated with dual-energy x-ray absorptiometry(DEXA)to measure the bone mineral density around the prosthesis after UKA.The American knee society knee score(KSS)score was obtained before and 12 months after surgery,and general data(gender,age,height,weight,body mass index,etc.)were collected.After the collection of these clinical data,the changes of bone mineral density in the regions of interest of the prosthesis after UKA were analyzed and discussed.ResultsAt the 12th month after surgery,25 patients who were followed up had no adverse events such as infection or loosening of the prosthesis.The KSS clinical score and KSS functional score were(87.82±3.33)and(84.41±3.30),respectively.The difference between(57.46±6.31)and(55.79±4.70)was significant(P<0.01).At 12 months postoperatively,the bone mineral density in the regions of interest around the orthotopic femoral prosthesis decreased by 4.80-9.23%,with an average reduction of 6.43%.The bone mineral density in the regions of interest around the lateral femoral prosthesis decreased by 4.76-10.96%,with an average reduction of 7.65%;bone density decreased by 3.86-21.56%in all regions of interest around the orthotopic tibial prosthesis,with an average reduction of 13.16%;The bone mineral density in the upper part of the humerus was decreased by 13.77%;Among them,the most significant decrease in bone mineral density in the regions of interest around the orthopedic femoral prosthesis was 9.23%of the lateral femoral condyle;the most significant reduction in the area of interest around the lateral femoral prosthesis was the posterior part of the femoral condyle(10.96%);The most significant reduction in bone density in the regions of interest around the tibial prosthesis was the upper tibia(21.56%).Compared with preoperative,the fastest time to decrease the bone density of the various regions of interest around the prosthesis is the first 3 months after surgery,and the bone mineral density is still decreasing in the third to sixth months after surgery.Bone mineral density in the region of interest was reduced to a minimum in the sixth month after surgery,while bone mineral density increased in the second half of the year.At the 12th month after surgery,some areas of interest were the medial femoral condyle(-9.23%,p=0.075),the upper tibia(-3.86%,p=0.789),and the femoral condyle(-5.26%,p=0.179);lateral femoral shaft(-4.76%,p=0.932),femoral condyle(-7.33%,p=0.052)and tibia(-11.50%,p=0.148),no significant difference compared with preoperative.ConclusionIn the first 3 months after UKA,the loss of bone around the prosthesis was the fastest,and the loss rate reached the highest in the 6th month after surgery.The bone mass in the area of interest around the prosthesis recovered from the 6th to 12th postoperative period,a small amount can be returned to no significant difference before surgery,and most of them are still significantly lower than before surgery.At the 12th month after surgery,the bone mineral density at the upper end of the femur,tibia and tibia away from the prosthesis decreased with preoperative,but there was no significant difference from the preoperative.The medial temporal femoral condyle,the medial temporal region of the humerus,and the lateral anterior and lateral humeral anterior region of the humerus,the posterior femoral condyle and the superior humerus,the bone mineral density of the region of interest closely associated with the prosthesis decline significantly.The medial bone mineral density of the femur and tibia was greater than that of the lateral side before and after surgery.