Study Of Tibial Intramedullary Nail Through Suprapatellar Approach

Background:Since AO scholars proposed the concept of biological internal fixation(BO),BO has been widely disseminated in the field of traumatic orthopedics in the world,and has been accepted and promoted by domestic trauma orthopedic surgeons.The connotation of BO is that it is necessary to protect the soft tissue and peripheral blood supply of the fracture as much as possible,and when it is firmly fixed,it should avoid pressing the fracture.Because intramedullary nail fixation has the advantages of minimal trauma and can retain the blood supply of periosteum and surrounding soft tissues at the fracture end to the maximum extent;it belongs to central fixation and can significantly reduce stress shielding compared with other fixation methods.It fits the BO concept and is gradually replacing plate and screw fixation as the preferred treatment for long tubular bone fractures(such as femur,tibia,etc.).At present,tibial intramedullary nail is mainly inserted through patellar ligament approach.This surgical method has the advantages of small trauma and convenient operation and is widely used in clinical practice.However,the incision of the Infrapatellar approach can damage the infrapatellar branch of the saphenous nerve,patellar tendon and infrapatellar fat pad.The operation may also damage the anterior horn of the medial and lateral meniscus,anterior cruciate ligament,intermeniscal ligament,tibial plateau and other structures.Postoperative pain often occurs in anterior knee area,which affects postoperative functional exercise and patients' satisfaction with the surgical outcome.Secondly,the Infrapatellar approach places nails under the position of the knee flexion of 120°,so the tendon of quadriceps is tense and the traction effect is increased,which makes the proximal end of the tibial fracture is displaced forward,thus making fracture reduction and maintenance difficult.In order to obtain satisfactory intraoperative fluoroscopy outcome,Infrapatellar approach often needs to change position repeatedly,which will increase fluoroscopy times and operation time,and even lead to loss of reduction due to the change of position.Therefore,how to improve the deficiency of tibial intramedullary nail surgery method is a problem that orthopaedics must solve.After reviewing the relevant literature,this study found that some foreign scholars have studied and reported the operation of tibial intramedullary nail through Suprapatellar approach.Therefore,this study carried out applied anatomical study of the approach,explored the feasibility and surgical methods of suprapatellar approach in Chinese population,and provided theoretical support for the design of a new intramedullary nail fixation system.Objective:To evaluate the advantages and disadvantages of Suprapatellar approach compared with Infrapatellar approach,and to evaluate the feasibility of the operation,so as to provide basis for the design and clinical popularization of new intramedullary nail.We performed simulated surgery and applied anatomy on cadaveric specimens to compare the surgical procedures to compared the surgical operation and approach anatomy of tibial intramedullary nailing via Suprapatellar approach and Infrapatellar approach.Methods:20 adult formalin-fixed cadaver specimens of lower limbs were randomly selected,10 cases of left lower limbs and 10 cases of right lower limbs(provided by Anatomy Department of Southwest Medical University).X-ray examination was performed on each specimen to exclude abnormal conditions such as fracture,deformity,tumor and osteoporosis.The above specimens were divided into the Suprapatellar(SP)approach group and the Infrapatellar(IP)approach group.The surgical position and the position of the incision were observed,and the length of the incision and the distance between the start point and the important structure in the knee joint were measured.To evaluate the safety and feasibility of tibial intramedullary nail inserted via Suprapatellar approach.Results:(1)Surgical position: In SP group,the intramedullary nailing operation was performed in a semi-extensional position of 30 degrees flexion of the knee.In IP group,the intramedullary nailing operation was performed at knee flexion position above 120 degrees of knee flexion.(2)The incision length of SP group was 25.58-34.26 mm,with an average of 29.91±3.12 mm;in IP group,it was 37.40-51.80 mm,with an average of 44.60±4.83 mm.The length of the incision in the SP group was shorter than that in the IP group,and the difference was statistically significant.(3)In SP group,the anterior and lateral cutaneous branches of femoral nerve were not injured,and the infrapatellar branch of saphenous nerve and patellar ligament were not injured.In IP group,the infrapatellar branch of saphenous nerve,patellar ligament and infrapatellar fat pad were injured directly.(4)The distance from the nail hole to the front of intermeniscal ligament(IML)in SP group was 0-6.02 mm,with an average of 3.02±2.02 mm;in IP group,it was 0-7.42 mm,with an average of 3.26±2.52 mm.There was no significant difference between the two groups.(5)The distance from the nail hole to anterior horn of medial meniscus(AHMM)in SP group was 0-12.04 mm,with an average of 6.92±3.73 mm,in IP group,it was 0-8.02 mm,with an average of 4.13±2.44 mm.There was no significant difference between the two groups.(6)The distance from the nail hole to anterior horn of lateral meniscus(AHLM)in SP group was 3.58-12.96 mm,with an average of 8.83±3.41 mm;in IP group,it was 4.02-9.56 mm,with an average of 6.00±2.26 mm.The distance from the nail hole in SP group was longer than that in AHLM group,and the difference was statistically significant.(7)The distance from the nail hole to the root of anterior cruciate ligament(ACL)in SP group was 4.78-12.02 mm,with an average of 8.06±2.29 mm;in IP group,it was 3.44-9.42 mm,with an average of 5.66±1.67 mm.The distance from the nail hole in SP group was longer than that in IP group,and the difference was statistically significant.(8)The distance from the nail hole to the front of medial tibial plateau(MTP)in SP group was 4.06-9.10 mm,with an average of 6.21±1.74 mm;in IP group,it was 5.22-11.36 mm,with an average of 8.35±2.19 mm.The distance from the nail hole in SP group was shorter than that in IP group,and the difference was statistically significant.(9)The distance from the nail hole to the front of lateral tibial plateau(LTP)in SP group was 4.44-9.38 mm,with an average of 6.56±1.55 mm;in IP group,it was 0-6.22 mm,with an average of 4.32±1.81 mm.The distance from the nail hole in SP group was longer than that in IP group,and the difference was statistically significant.(10)The structural damage rate of the knee joint in the SP group was 30%,and that in the IP group was 40%,but the difference was not statistically significant.Conclusion:(1)The experimental results show that tibial intramedullary nail placement via Suprapatellar approach is feasible.(2)The Suprapatellar approach is performed in the semi-extension position of knee joint flexion at 20-30 degrees.The operation of tibial intramedullary nail is convenient and safe.It has important clinical significance for fracture reduction and maintenance reduction.(3)Suprapatellar approach has the following advantages over Infrapatellar approach in tibial intramedullary nail surgery: 1)Suprapatellar approach's incision avoids damage to the soft tissue below the knee joint and it is suitable for the treatment of proximal tibial fractures with poor soft tissue conditions;2)Suprapatellar approach avoids injury to the infrapatellar branch of saphenous nerve and patellar ligament,which reduces the risk of postoperative anterior knee pain;3)It avoids the problem that fluoroscopy needs to change position repeatedly during Infrapatellar approach,makes the operation process more convenient and fast;4)Although the operation of Suprapatellar approach may also damage the intra-articular structure of knee joint,the risk of injury of intra-articular structure is lower than that of Infrapatellar approach.(4)This study provides a theoretical basis for designing a tibial intramedullary nail system suitable for Chinese people through Suprapatellar approach in the future.