A Basic And Clinical Study On Minimally Invasive Total Knee Arthroplasty Through A Mini-incision

PartⅠA clinical anatomical study of the medial extensor mechanism and descending genicular artery of Chinese knee jointObjective Through anatomical measurements of the distal most insertion point of the vastus medialis obliquus(VMO)tendon on the patella,the length of the VMO tendon and the course of the descending genicular artery of Chinese knee joint to provide anatomical bases for chosing the surgical approach and protecting the extensor mechanism and descending genicular artery during total knee arthroplasty(TKA).Methods The sample consisited of 16 adult cadaver knee specimens fixed by Formalin and infused by red latex through the femoral artery(9 male side,7 female side).When the knee was dissected,following values were measured:1.the distal most insertion point of the VMO tendon on the patella expressed as a percentage compared to the whole length of the patella;2.the length of vastus medialis tendon;3.the angle between the course of the descending genicular artery and the horizontal line of the knee joint;4,the distance in the vertical direction from the most prominent point of the patella to the descending genicular artery.Results The distal most insertion points of the VMO tendon on the patella were mostly near the midpole of the patella,an average of 58%(45%～72%).The average length of the VMO tendon was 1.3 cm(0.5～2.2cm).The average angle between the course of the descending genicular artery and the horizontal line was 59 ^{51°～71°}. The average distance in the vertical direction from the most prominent point of the patella to the descending genicular artery was 4.2cm(3.3～5.2 cm).Conclusions The distal most insertion points of the VMO tendon on the patella were mostly near the midpole of the patella.Anatomically based,minimally invasive total knee arthroplasty through a medial parapatellar approach,a midvastus approach or a Q～S approach will violate a small portion of the medial extensor mechanism and just the subvastus approach can be called Q～S approach.The turning point of the subvastus approach should be near the midpoint of the patella.As the shortest length of the VMO tendon was only 0.5cm,a capsular incision done excessively medially may vertically injury the VMO.On account of the average angle between the course of the descending genicular artery and the horizontal line was 59°(minimum:51°),as well the average distance in the vertical direction from the most prominent point of the patella to the descending genicular artery was 4.2cm(minimum:3.3cm),the descending genicular artery can be protected when the capsular incision of the midvastus approach extends more medially and inferiorly than it during TKA.PartⅡA comparative study about total knee arthroplasty through a mini-incision medial parapatellar approach and a traditional medial parapatellar approachObjective To compare and study the clinical early results of the mini-incision medial parapatellar approach and the traditional medial parapatellar approach for total knee arthroplasty.Methods 29 primary total knee arthroplasty have been performed through a mini-incision medial parapatellar approach and 39 primary total knee arthroplasty through a traditional medial parapatellar approach during January 2005 to October 2007.All the operations were performed by one experienced surgeon and the two groups were compared according to the length of the skin incision,operation time,postoperative drainage,the declined value of hemoglobin at postoperative day I,VAS score within postoperative 24 hours,amount of blood transfusion,rate of blood transfusion,amount of additional analgesic using,active straight-leg raising time,starting time of ambulation, radiographic limb alignment and prosthesis positioning,postoperative range of motion HSS score at postoperative 3 months and complications.All the data were statistically analysized by SPSS10.0 software,the quantitative data using t-test and the qualitative data using Chi-square test.Results There were no serious complications in the two groups.The positioning of all the components were normal except one abnormal positioning of tibial prosthesis in one case in the MIS group.In the MIS group:The average length of skin incision was 10.5 cm,the average amount of postoperative drainage was 89.8ml,the average declined value of hemoglobin at postoperative day 1 was 18.4g/l,the average VAS score within postoperative 24 hours was 2.6 points,the average amount of blood transfusion was 231ml,the rate of blood transfusion was 14/29,the average active straight-leg raising time and starting time of ambulation was respectively postoperative day 5 and 6,and the average HSS score at postoperative 3 months was 85 points.While in the traditional group:The average length of skin incision was 18.5cm,the average amount of postoperative drainage was 202.6ml,the average declined value of hemoglobin at postoperative day 1 was 27.8g/1,the average VAS score within postoperative 24 hours was 3.8 points,the average amount of blood transfusion was 528ml,the rate of blood transfusion was 32/39,the average active straight-leg raising time and starting time of ambulation was respectively postoperative day 8 and 9,and the average HSS score at postoperative 3 months was 80 points.There were significant differences between the two groups(P <0.01).In the MIS group,the average range of motion of knee joint when discharged from hospital,postoperative 6 weeks and 12 weeks was respectively 92°,105°,115°,while the traditional group was respectively 87°,99°,108°.The differences about above between the two groups were significant(P<0.01).The amount of additional analgesic using of the MIS group was significantly less than the traditional group(P <0.01).When comparing the operation time of the M1S group with the traditional group,there was no significant difference(P>0.05).Conclusions The clinical early results of total knee arthroplasty through a mini-incision medial parapatellar approach were superior than a traditional medial parapatellar approach.It can be performed safely and will not increase operation time and complications.PartⅢA comparative study about total knee arthroplasty through a mini-incision medial parapatellar approach and a mini-incision midvastus approachObjective To compare and study the exposure satisfaction and clinical early results of the mini-incision medial parapatellar approach(MPP)and the mini-incision midvastus approach(MMV)for total knee arthroplasty.Methods 29 primary total knee arthroplasty have been performed through a mini-incision medial parapatellar approach and 23 primary total knee arthroplasty through a mini-incision midvastus approach during January 2005 to October 2007.All the operations were performed by one experienced surgeon and the two groups were compared according to the length of the skin incision,operation time,rate of lateral retinacular release,postoperative drainage,the declined value of hemoglobin at postoperative day 1,VAS score within postoperative 24 hours,amount of blood transfusion,amount of additional analgesic using,active straight-leg raising time,starting time of ambulation,radiographic limb alignment and prosthesis positioning, postoperative range of motion,HSS score at postoperative 3 months and complications. All the data were statistically analysized by SPSS10.0 software,the quantitative data using t-test and the qualitative data using Chi-square test.Results Except partial avulsion of the patellar tendon from the tibial insertion in one patient in the MMV group due to inappropriate traction of assistant during operation, there were no serious complications in the two groups.The positioning of all the components were normal except one abnormal positioning of tibial prosthesis in one case in each group.In the MPP group:The average length of skin incision was 10.5 cm,the average amount of postoperative drainage was 89.8ml,the average declined value of hemoglobin at postoperative day 1 was 18.4g/l,the average VAS score within postoperative 24 hours was 2.6 points,the average amount of blood transfusion was 231ml,the average active straight-leg raising time and starting time of ambulation was respectively postoperative day 5 and 6,the average range of motion of the knee joint when discharged from hospital,postoperative 6 weeks and 12 weeks was respectively 92°,105°,115°,and the average HSS score at postoperative 3 months was 85 points. While in the MMV group:The average length of skin incision was 11 cm,the average amount of postoperative drainage was 85.6ml,the average declined value of hemoglobin at postoperative day 1 was 19.7g/1,the average VAS score within postoperative 24 hours was 2.5 points,the average amount of blood transfusion was 221ml,the average active straight-leg raising time and starting time of ambulation was respectively postoperative day 4.5 and 5.3,the average range of motion of the knee joint when discharged from hospital,postoperative 6 weeks and 12 weeks was respectively 93°,108°,117°,and the average HSS score at postoperative 3 months was 86 points.The differences about above between the two groups were not significant(P>0.05).The differences about the rate of lateral retinacular release and the amount of additional analgesic using between the two groups were also not significant(P> 0.05).The average operation time of the MMV group(88 minutes)was longer than the MPP group(75 minutes)(P<0.01).Conclusions Total knee arthroplasty can be safely performed through the two mini-incision approaches and their early outcomes were satisfactory,so the choice of surgical approach may mainly depend on the surgeon's habit and familiarity with such approach.