Anatomy And Biomechanics Study On The Relationship Between The Soft Tissue Around The Knee And The Stability Of Patellofemoral Joint

1.Objective:1.1 To observe the soft tissue around the knee,especially the morphological anatomy characteristics of the medial patellar retinaculum(MPR),lateral patellar retinaculum(LPR) and the quadriceps femoris.Preliminary study the contribution of the 4 muscles of the quadriceps femoris and the medial retinaculum in the stability of the patellofemoral joint.With a view to understand the pathological mechanism of lateral petellar instability(LPI),and to provide a theoretical basis for correct diagnosis, a reasonable treatment as well as a surgery designing for the lateral patellar retinaculum releasing and the medial patellofemoral ligamen repairing.1.2 Through biomechanical tests,to simulate 4 operating conditions of the 4 muscles of the quadriceps femoris of physiology or pathologic,to measure the force which subluxated the patella,to study the contribution of the 4 muscles of the quadriceps femoris in the stability of the patellofemoral joint,and to provide a theoretical basis for clinical treatment and rehabilitation choosing,which with the quadriceps the relevant and for the patellofemoral joint instability.1.3 Fracturing the MPR to simulate pathologic conditions,doing the biomechanical test of patellar subluxation on these knees.And then fracturing the LPR furthermore to simulate the clinical surgical treatment,then do the test again. Measuring the forcement which subluxated the patella,to study the effect of MPR and LPR in the stability of the patella,and to study the function and effect of releasing the lateral retinaculum in clinical.With a view to provide a biomechanical basis for the clinical treatment for LPI,and to find available treatment,which can correct the abnormal patellar track.2.Methods:2.1 Anatomy observation:6 adult anticorrosive cadavers were choosed.We observe the morphological anatomy characteristics of the soft tissue around the knee, especially the MPR,LPR and the quadriceps femoris.The angles of Muscle fiber were measured.2.2 Biomechanical Measurement Test2.2.1 Test-1:6 fresh human cadaver knees with quadriceps tendon,ligaments around the knees as well as complete MPR,LPR were flexed at 7 different angles, loading the 4 muscles of quadriceps femoris to simulate the muscle strength under 4 operating conditions of physiology or pathologic,then load the patella making it subluxation(we definited it as the patella deviate 1.0 cm from normal position to lateral in this study),and note the loads(force).The data were statistical analysised with SPSS 13.00.2.2.2 Test-2:on the 6 fresh human cadaver knees which were used in Test-1,the quadriceps femoris were loaded to simulate normal muscle strength conditions.First we measure and record the loads(force),which making patella subluxation(we definited it as the patella deviate 1.0 cm from normal position to lateral in this study),and we have got the data in Test-1.Intervention 1:release the MPR to simulate pathologic conditions,then repeat the manipulate and measure above,recording the loads(force).Intervention 2:Release the LPR furthermore to simulate clinical surgical treatment,then repeat the manipulate and measure above,recording the loads(force). The data were statistical analysised with SPSS13.00.3.Results:3.1 Anatomy observation:vastus lateralis Muscle(VLM),vastus medialis muscle (VMM) and unit rectus(UR),respectively,into 33.50°±6.19°angle,54.5°±8.20°angle. The fiber of VMM was divided into vertical beams and oblique beams.The oblique beams, which is also called the vastus medialis obliquus muscle(VMO),and unit rectus(UR) into75.50°±8.20°angle.The fiber at the lowest almost horizontal line going.The Expansion part of the tendon of the quadriceps femoris expand into being MPR,LPR. In the medial of knee joint,there was a part of retinaculum connecting femoral condyle and the above 2/3 medial margin of the patella,which was called medial patellofemoral ligamen(MPFL).Its length is(47.60±5.59)mm,and its width is variation from 8 mm to 26 mm.In the deep medial of knee joint,the retinaculum by the three major component parts:lateral transverse ligament(LTL),lateral patellotibial ligament (LPL),epicondylopatellar ligament(EL).The lateral transverse ligament from the lateral border of patella central stop iliotibial band(ITB).3.2 Biomechanical Measurement Test3.2.1 Test 1:In physiologic condition,at 20°in the process of the knee flexing, the loads which subluxate the patella is smallest(61±13N),as about one-third of 90°; slackened the vastus medialis,the loads decrease obviously when flexing 10°-30°,and the difference had significant difference(P＜0.05);slackened vastus lateralis in addition,the loads decrease obviously in the whole flexing process,and it had significance(P＜0.05).3.2.1 Test 1:when no obvious abnormalities in the muscle,Intervention 1: Release the MPR,mainly MPFL,the loads which subluxate the patella decrease obviously,and the difference had significant difference(P＜0.05);Intervention 2: Release the LPR furthermore,mainly lateral transverse ligament,the loads decrease to go a step further,but had no significant difference(P＞0.05).4.Conclusions:4.1 From the morphological point of view,the strength of each muscle of quadriceps femoris,especially the muscle strength of VMM and the attachment point of VMM on the patella,playing an important role in maintaining the normal relation between patella and femur.We should not neglect the recovery of the quadriceps in clinical treatment for the patella lateral subluxation and/or patella lateral tilt.In the MPR and LPR,the MPFL and the lateral transverse ligament(LTL) play a greater role in restricting lateral displacement of the patella.Preliminary view is that the VMM losing efficacy or(and) the MPR injury may be one of the reasons for patellar dislocation.4.2 The strength of each muscle of quadriceps femoris has significance function in maintaining the normal relation of the patellofemoral joint,and the imbalance of quadriceps strength has a greater impact on the contact stress and distribution status of patellofemoral joint as well as location of the patella.Normal muscle strength is an important condition ensuring the stability of joint exercise.The strength lost or weakened of VMM will significantly cause reducing of power patellar lateral dislocation or subluxation required,and easily lead to patellar dislocation or subluxation.So in the course of treatment and rehabilitation,attention should be paid to strengthening the training of the quadriceps,especially to the recovery of VMM. VLM have limited impact on the maintenance of the patella stability and avoidance of lateral subluxation.The entire quadriceps played an important role in the process of prevention,treatment and rehabilitation for patellar lateral subluxation,so the VLM should not be damaged when operating,and the strength recovery of VMM should be emphasised when rehabilitating.For the elderly,muscle strength increasing and balance between muscles improving can weaken the impact of load and increase the stability of the knee,thus can be the treatment of osteoarthritis of the knee.After total knee arthroplasty,quadriceps strength training is a very important content that run through the whole process of rehabilitation.4.3 MPR plays an important role in maintaining the stability of the patella and in maintaining the normal trajectory of the patellofemoral joint,and injuryd MPR is the mainreason for the instability of trajectory of the patellofemoral joint.MPR fracture will significantly cause reducing of power patellar lateral dislocation or subluxation required,and lead to patellar dislocation or subluxation.So in the clinical treatment for patella recurrent lateral dislocation/subluxation,attention should be paid to the repairing or reconstruction of the medial patellofemoral ligamen.Releasing LPR well further destroy the stability of the patellofemoral joint.When releasing MPR,at the same time releasing LPR,the effect of dislocation further amplified.With a view to prevent and treat the lateral patella dislocation,we can not release the lateral stability structure in case of the MPR fracture or relaxation.It will further increases the clinical symptoms and leads to serious dysfunction of the knee joint.In the clinical treatment of patellar dislocation,releasing the lateral patellar retinaculum is not a best choice,and we should pay great attention to the tight of medial patellar retinaculum and the repairing or reconstruction of the medial patellofemoral ligamen.