Anatomic Study And Its Application Of A Modified Carlson’s Posterolateral Approach For The Treatment Of Posterolateral Coronal Fractures Of The Tibial Plateau

Tibial condylar fractures, often affecting the articular surface of the tibial plateau, is also known as tibial plateau fractures in clinic. The fracture can also be combined with injuries of meniscus, or even cruciate ligament and lateral collateral ligament during the injury, which can easily cause adverse outcomes, such as arthrodynia, stiffness, instability or deformity. Because of the presence of the physiological knee valgus angle, the lateral plateau fractures were the most common. The posterolateral column fractures of the tibial plateau is a special type of fracture in the lateral plateau, and is a simple fracture of the posterolateral condyle on the coronal plane of the tibial plateau fracture. The fracture is usually characterized by pure posterolateral articular surface depression, pure splitting, splitting combined articular surface depression. At present, open reduction and internal fixation(ORIF) has become main therapy for the treatment of tibial plateau fractures. This operation can repair and flat the joint surface. Because ordinary X-ray diagnosis of the posterolateral fracture have limitations, we can not diagnose immediately. CT or MRI is necessary and essential for the diagnosis including the type and scope of injury. Now there is no uniform standard for the operative treatment of fractures. But any surgical approach and the method should meet the purpose of small trauma, enough exposure and strong internal fixation. However, by standard lateral approach or anterolateral and posterior approach are difficult to achieve above desired effects. From a biomechanical perspective, using support plate to pressurize the fracture is most reliable. In 1998, Carlson reported involved inside and outside platform back tibial condyle fracture by knee joint surface inside and outside after bilateral incision for exposure, and plate fixation treatment. Carlson approach not specifically for treatment of fracture of the lateral column,and its incision deviates laterally, which usually intercrosses with the main posterolateral nerves, cause nerve injury during operation. The postoperative incision scar is also easy to causing compression of nerves and paralysis. Also involved in the fracture of the lateral column after the place of the cross check point inadequate exposure, fixed cause fracture of the cross check point after treatment. As anatomical structure is relatively complex for knee posterolateral approach, Because of knee posterolateral approach anatomical structure, it led to difficulty for operative procedure. involved in the operation difficulty, It is important to know the knee posterolateral approach related structures, ligaments, tendons, blood supply and innervation for reducing surgical trauma to this site, retaining its blood supply and enhancing its efficacy. Further studies of this anatomical observation and its clinical applications are needed.Objective: To determine the reliability of this approach by anatomical observation, measurement and analysis of major vessels or nerves involved in this modified Carlson’s posterolateral approach. At the same time to determine whether there is sufficient space for internal fixation, providing key guidance for clinical applications. To explore the surgical skills and clinical efficacy of the modified Carlson’s posterolateral approach for the treatment of posterolateral coronal fractures of the tibial plateau.Methods:(1) Anatomic observation and measurement: 20 cases of adult cadaver lower limb specimen, 10 cases of male, 10 cases of female. Firstly do stratified gross anatomy of the knee region, taking a posterior midline incision of this region from the middle distal third of thigh to the middle of leg, by reflecting the skin, subcutaneous tissue layer in order. Then observe common peroneal nerve, lateral sural cutaneous nerve, so as to ensure the safety area for the operation incision. After cutting deep fascia and speration step by step, to observe the posterolateral major ligaments of the knee joint and muscular tissue of adhesion characteristics, then to certify the surgical approach space.After completely stripping gastrocnemius and soleus muscle, exposing the popliteal neurovascular bundle, to observe and anatomically measure the possible affecting incision regions including popliteal neurovascular bundle, the anterior tibial artery and lateral knee arteries, then to analysize the feasibility of this approach in clinic. All the related data were statistically processed.(2) Clinical practice: The patients(from January 2010 to December 2013) were divided into control group and observation group based on different treatment strategy. Using anterolateral approach(control group) and modified Carlson posterolateral approach(study group) exposed tibial plateau posterolateral, respectively, on a random sample of 48 cases of surgical treatment.They were 56 males and 40 females,with a mean age of 41 years(range,from 19 to 65 years).The patients were treated with buttress plate fixation via a modified Carlson’s posterolateral approach.The knee joint functions were estimated with the Hospital for Special Surgery(HSS) score system and Rasmussen score system at 3, 6 and 12 months postoperatively.Through the observation of injuried knee whith or without the index incuding pain, joint activities, infection, deep vein thrombosis, TPA, and PA angle and related complications, to make curative effect evaluation of the modified operation.Observe whether the operated limb Imaging data based on the measurement of angle of knee TPA, PA and joint flexion mobility to evaluate the curative effect were compared immediately, 3, 6 and 12 months after operation respectively.Results:(1) The horizontal distance from the lateral sural cutaneous nerve to medial margin of the fibular head was 1.696±0.396 cm. The vertical distance of lateral sural cutaneous nerve issue from the common peroneal nerve to the upper margin of fibula head was 5.755±1.607 cm. The vertical dstance from lateral inferior genicular artery to the upper edge of fibular head was 1.839±0.364 cm, and the horizontal distance from this artery to the medial margin of fibular head was 1.707±0.272 cm. The distance from the origin of anterior tibial artery to the hiatus of crural interosseous membrane was 2.397±0.304 cm. The vertical distance from the hiatus of crural interosseous membrane to the upper margin of fibular head was 4.794±0.354 cm, and the horizontal distance from this hiatus to the medial margin of fibular head was 0.947±0.217 cm. Because of the need to expose the posterolateral tibia plateau, the soleus and the popliteus of partial muscle attachment points on tibial need to be dissected appropriately. For the lateral inferior genicular artery relatively restrict the surgical exposure, it can be ligated during operation. For restriction of the anterior tibial artery, we could not further expose the tibial surface below the level of crural interosseous membrane hole. Thus expanding crural interosseous membrane hole is a good methed for appropriately increasing vascular stretch range.(2) Clinical practice: All the patients received postoperative 12 to 18 months(mean 15.7 months) follow-up, X-ray film within these patients after operation 3 to 4 months have shown all bony fractures healed. Study group of HSS knee joint function scores were 90 to 100 points, an average of 94.3 points. The fracture healing time, postoperative full weight-bearing time and postoperative drainage of study group patients was significantly less than those of the control group. Rasmussen radiation score was 16 to 18 points, an average of 17.7 points. No complications associated with the approach were observed and there was neither infection nor fixation failure.The excellent rate of study group and control group was 95.83% and 83.34%, respectively(P < 0.05).Conclusion:(1) On the premise of familiar with the anatomy structure, using modified Carlson’s knee posterolateral approach to treat the posterolateral coronal fracture of the tibial plateau is a good choice, for it has advantages such as less trauma, enough exposure, good reduction and rigid fixation. Because of anterior tibial vessel bundle is relatively fixed in the bone fissure hole, the cases with fracture line below the level of crural interosseous membrane hole should be cautious to use this method in case of its injury.(2) Because the modified Carlson’s posterolateral approach can provide direct enough exposure to protect ligamentous structures and the soft tissue around the posterolateral fragments, utmost to provide the biomechanical strength of the posterolateral internal fixation. The modified Carlson’s posterolateral approach is less bleeding, postoperative bone healing fast, early weight bearing, so it has more advantages compared with the traditional approach for internal fixation of the fractures, and can be effectively used to treat posterolateral coronal fractures of the tibial plateau, this method is worthy of clinical application. However, it is more dangerous to remove the plates by this approach. If there are compound factures including medial fractures and posteromedial fractures of tibial plateau, this approach and fixation methods should be combined with other means.