The Relationship Between The Anatomic Of The Vastus Medialis And Surgery Approaches In Total Knee Arthroplasty

Background:Total knee arthroplasty(TKA) has been becoming the best treatment method to cure knee osteoarthritis. TKA has been highly successful procedure with the goals to relieve patient pain, improve the knee function,Correct knee articular valgus and varus deformity. There are large quantities of cases showing components survival rates of more than 90% in follow-up over 10 years【1 2 3】. Statistical data shows that there are more than 51% people having knee osteoarthritis over the age of 60 and are accepted to undertake TKA patients increasing year by year in China【4】.The TKA procedure is complexity, there are a lot of influence factors of outcome in it, included proper patient selection, surgical technique, the choice reasonable components, quality of the prosthesis, postoperative rehabilitation. The appropriate surgical approach is the most important for exposure in TKA procedure. There are several common knee replacement approaches, medial parapatellar, midvastus and subvastus approaches, all of them relevant anatomy are closely related with the vastus medialis.1. The vastus medialis morphology is important for choice TKA surgery exposure approaches and assessment of this may be help surgeon to choose which approach in the procedure. 2. How to assess the advantage and disadvantage of TKA approach is closely related with whether to damage of the vastus medialis.3. It is obvious relationship between postoperative complications and the injury of vastus medialis muscle, particularly to facilitate patellar complications, these complications include subluxation, dislocations, and avascular induced fracture of the patella.There have been only a few reports about the anatomy of the vastus medialis. which could not satisfy the applied anatomy of TKA. A little has been written about the association between the vascular and muscular anatomy of vastus medialis and surgery approaches of TKA in China. The objective of this study was to reduce the injuries during surgical procedures in TKA to provide the reference for Clinicians to choose the best approaches.PartⅠ:The relationship between anatomical basis of vastus medialis muscle and subvastus approachObjectiveThis study was to observe morphological and anatomical vastus medialis,and to determine how surgical approaches that provides the basis of local anatomic in TKA,especially to subvastus approachMethodsA total of 20 cadaveric knee and 80 vivo knee were observed and the lengths of VM insertion on patella were measured separately by the methods of anatomic dissection and surface projection.The distribution results of the VM patellar insertion in the three conditions were compared. Observed and descriptive statistics were performed on all fiber angle measurements and frequency of fascial plane presence in cadaveric dissection group.ResultsAccording to the different muscle fiber angle ,The vastus medialis (VM) muscle has been described as being composed of two separate divisions: the vastus medialis longus (VML) 19.5°±6.4°proximally and the vastus medialis oblique (VMO) 48.6°±7.2°distally.The ratio of the vastus medialis body length to the patellar length was 40% to 60% in 55.0% specimens (11 cases). The ratio was (47.8±15.1)%, (48.7±15.4)% and (46.7±14.8)% respectively in the Cadaver-surface-observation Group, the Autopsy Group and the in vivo surface Group, with no statistical difference (P>0.05). Conclusions1.The researchers found that 80% of VM insertion on the patella not more thanⅢof the patella in cadaveric dissection group2. Preoperative evaluation of the body-surface-projection of the VM patellar insertion has a referential value to the selection of the TKA approach.PartⅡThe relationship between neurovascular of vastus medialis muscle and midvastus approachObjectiveThe purpose of the current study was to observe neurovascular of vastus medialis muscle,and to reduce the damage in midvastus approach.MethodsThe neurovascular and adjacent of the vastus medialis in adult lower limb specimens were dissected and measured. Results: The most distal femoral artery branched to dominate the vastus medialis oblique(VOM), whose X-axis range (35.2mm, 72.3mm) , Y-axis range (41.4mm,78.9mm). The most distal femoral nerve branched extensively to innervate (33.4mm,77.8mm), Y-axis range (43.4mm,89.3mm). The average distance between the patella margin and the popliteal vessels was 86mm±13.8mm and corresponding range (55.2mm minimum to 118.6mm maximum).ConclusionThere is a 33mm*41mm"lack of the neurovascular zone"locating at the vastus medialis, it is possible to decrease potential neurovascular injury operating in the area.