Tibial plateau fractures are one of the most common intra-articular fractures in knee trauma, and are commonly classified by Sehatzker: (1) splitting of the lateral plateau without articular surface collapse; (2) splitting and compression fractures of the lateral plateau; (3) compression of the lateral plateau alone; (4) medial plateau fractures; (5) plateau fractures with varying degrees of articular surface collapse and displacement of the condyle; and (6) plateau fractures with epiphyseal separation. They are often associated with anterior and posterior cruciate ligament and collateral ligament injuries of the medial and lateral menisci, and improper management may cause deformity, force line or stability problems in the knee, resulting in joint dysfunction. In S c h a t z k e r III – V I fractures, the fracture is significantly displaced, the joint surface is severely damaged, and it is often combined with heavy soft tissue injuries, injuries to the meniscus, cruciate ligaments, and collateral ligaments are complex tibial plateau fractures.
At present, the treatment of tibial plateau fracture is mostly based on good fixation to maintain the anatomical repositioning, supplemented by good fixation to secure and complete the articular cartilage surface and joint appendages to meet the functional recovery needs, among which correct and effective internal fixation is the key to anatomical repositioning and functional recovery. For collapsed tibial plateau fractures, traction, external fixation, and simple arthroscopic surgery are difficult to achieve articular surface repositioning and damaged ligament repair, and are prone to serious complications such as traumatic arthritis and joint instability, so open surgical treatment is required, and different fixation methods are used according to different subtypes to achieve the most accurate articular surface repositioning through incision and repositioning. In the surgical treatment of collapsed tibial plateau fractures (at least 50% of Schatzker II and III types), the goal of treatment is the reconstruction of the joint surface and strong fixation, and in recent years, filler implant treatment has developed rapidly and is widely used. There are many filler materials required for bone grafting, which require early healing of the bone tissue at the implant site in addition to a certain degree of resistance to compression. Autologous iliac bone graft was used for filling bone graft, but its use is greatly limited by many disadvantages, such as limited amount of graft bone, painful symptoms [1], complications at the donor site [2], insufficient biomechanical strength, and bone atrophy at the graft site due to resorption of autologous graft bone. Artificial bone graft material has the characteristics of less deformable and bony supporting effect of bone filler thus has greater advantages than autologous bone graft.
1. Biomechanical characteristics of tibial plateau fracture
The tibial condyle is composed of spongy bone, which is easily fractured or collapsed by external compression or impact. The medial cortex of the tibia is harder than the lateral one, and most of the trauma is knee valgus position, so there are more fractures of the lateral condyle than the medial condyle. When the normal tibial plateau is loaded, the forces on the medial and lateral plateaus are basically the same, while the medial side is subjected to more forces than the lateral side when walking, which leads to an increase in pressure per unit area when the plateau surface collapses, and this pressure exceeds the regenerative capacity of articular cartilage, which produces traumatic arthritis [3]. Experiments have shown that the intra-articular pressure changes significantly when the joint surface collapses more than 1.5 mm, and increases significantly when it exceeds 3 mm or more. The prognosis is worse when the collapse leads to knee instability [4]. It has also been experimentally demonstrated that accurate repositioning and strong fixation of articular cartilage fractures help cartilage to heal in the form of hyaline cartilage. Therefore, according to the above biomechanical characteristics, accurate alignment of the articular surface, strong fixation of the fracture, and early movement can minimize the occurrence of traumatic osteoarthritis and enable the joint to achieve optimal function. The integrity of the joint surface, especially the weight-bearing joint surface, is of great importance to the outcome. Effective fixation is not only an effective consolidation of anatomical repositioning, but also the basis for postoperative functional recovery training, which is of great significance for the treatment of patients with tibial plateau fractures.
2.Surgical treatment of injectable calcium phosphate filled bone graft with supporting plate
Recent clinical studies have shown that the surgical treatment of collapsed tibial plateau fractures with injectable calcium phosphate filler implants plus support plates is an effective treatment method, and injectable calcium phosphate has good clinical application prospects as a bone graft replacement material [6]. It serves as a filler for the defect area and also has a repair function. Some studies have pointed out that fracture collapse greater than 5 mm and no pre-injury degenerative joint degeneration are considered as indications for this method. However, its long-term efficacy, whether its resorption is completely synchronized with bone formation and whether it forms bone defects after resorption need to be further studied.
3. High-intensity injectable calcium sulfate implant for tibial plateau fracture
The clinical effect of high-intensity injectable calcium sulfate (MIIGX3) in the treatment of tibial plateau fractures was investigated. All patients were evaluated by imaging prior to treatment for joint surface integrity, bone regeneration, and the process of resorption of MIIGX3. Rasmussen’s Core System was also used to assess recovery of joint function after treatment. Twenty-eight of the 31 patients in the study were successfully followed up for a mean of 14.6 months. Bone healing was achieved in all patients. Complications that occurred included wound oozing and joint collapse. According to Rasmussen’s Core System assessment, patients had good knee function after treatment. Imaging data six months after surgery showed equivalent bone density to the surrounding cancellous bone at the MIIGX3 site, and the use of MIIGX3 for tibial plateau fractures demonstrated better intraoperative stability and improved safety of early knee motion. The results suggest that the application of MIIGTMX3 or MIIGTMX3HVsc injectable artificial bone graft material for tibial plateau fractures can effectively avoid fracture redisplacement and loss of articular surface height, has no biocompatible adverse effects with the host, and has the characteristics of improving the safety of early joint function and exercise. [7].
4. Surgical treatment of lateral tibial plateau depressed fractures assisted by using porous peptide particles
In this experimental study, BRYNJO et al. supported the elevated cartilage surface with porous peptide particles [8,9], which had been used as a hip prosthesis, on the basis of screw or plate supported internal fixation, and all four cases of tibial plateau depressed fractures in the clinical trial achieved better clinical outcomes and imaging results.
The study noted the following advantages of porous peptide particles over autologous bone grafts and other bone substitutes for tibial plateau depression fracture attachment: first, the peptide particles are not resorbed, which means that intraoperative joint plane fitting can continue throughout the repair phase. Another advantage is that the peptide pellets are easier to obtain than bone banks, the risk of infection is much lower, and the peptide pellets do not break down (e.g., they do not cause thermal damage to the bone), so there is no time pressure during intraoperative management. It also reduces the operative time and patient pain because bone is not obtained from the iliac bone; the stability of the fracture site is particularly good with peptide pellets, and studies have shown that peptide pellets as a bone substitute can also promote bone growth [10].
Discussion]
1. pay attention to combined ligament injury.
The knee joint is a uniaxial joint, and its stability depends on the composite of the osteoarticular surface, meniscus and articular ligament, especially the cruciate ligament is closely connected with the meniscus, forming an “8” structure in the knee joint, which is the core structure of the knee joint stability system [11]. Therefore, the treatment of tibial plateau fractures with ligament injury should not only achieve anatomical repositioning and reliable internal fixation, but also early and comprehensive ligament repair in order to obtain satisfactory results. The combined meniscus injury should be repaired and preserved as much as possible.
2. Timing of surgery and indications for surgery
It is generally accepted that complex tibial plateau fractures for which surgery is indicated should be performed in an emergency after completion of relevant examinations such as frontal, lateral and oblique x-ray of the knee, otherwise it should be delayed until 7-10 days after the injury when the tissue reaction has subsided. Patients should undergo temporary external fixation or distal tibial traction, but complex tibial plateau fractures are often associated with severe soft tissue abrasions and contusions, so surgery should be postponed for those with significant swelling and poor skin conditions, and supplemented with decongestion and bruising. In summary, complex tibial plateau fractures are high-energy injuries with varying degrees of bicondylar or medial condyle displacement or collapse fractures, so active surgical treatment is generally advocated, but it is believed that surgery should be contraindicated in older patients with significant degenerative degeneration of the knee joint and in those with severe bilateral plateau comminution that cannot be repaired [12].
3. Intraoperative considerations
The intraoperative examination should be comprehensive, and for those with combined cruciate ligament and collateral ligament injuries, effective internal fixation should be performed along with appropriate treatment, as the articular cartilage surface is the basis for good repositioning. The surgical incision needs to meet the adequate exposure of fracture collapse. However, attention should be paid to the protection of soft tissues to avoid excessive stripping and reduce the incidence of flap necrosis. The fixation should ensure effective bone grafting for compressed and collapsed fractures after prying up, but should not be overfilled to avoid joint separation and displacement. The meniscus should be repaired as much as possible unless it is severely damaged.
4.Postoperative recovery and functional exercise
It is not advisable to put on weight too early after surgery, otherwise the joint surface is prone to tilt or collapse. Therefore, early postoperative functional exercise with delayed weight-bearing is of great significance to the functional recovery of the knee joint. Salter believes that CPM (passive lower limb joint mobilizer) can increase the nutritional and metabolic capacity of the joint, stimulate the differentiation of multipotent mesenchymal cells into articular cartilage, and accelerate the healing of articular cartilage and its surrounding tissues [13]. The current consensus is that the application of C P M allows passive movement of the knee joint after surgery and provides a good foundation for preventing knee adhesions. It is recommended that a combination of quadriceps isometric contraction exercises and CPM functional exercises be performed in the early postoperative period to reduce limb swelling and improve articular cartilage nutrition.Honkonen et al. concluded that knee stiffness increases significantly in tibial plateau fractures with braking for more than 4 weeks, so it is recommended that for Schatzker type I, type II, and type III fractures, partial weight-bearing is generally allowed after 3-6 weeks of clear injury healing. Full weight-bearing exercises should be strictly limited to more than 3 months postoperatively, which has a significant effect on the recovery of the knee joint.
Conclusion
The surgical treatment of collapsed tibial plateau fractures is difficult and requires a detailed history and a thorough physical examination and imaging to properly assess the joint injury, as well as the selection of the appropriate timing of surgery, appropriate bone graft material and good technique and scientific postoperative functional recovery. However, the long-term efficacy of each implant bone filling treatment plan, the effect of the filler on bone regeneration and whether its resorption is completely synchronized with bone formation, and whether it forms a bone defect after resorption need to be further investigated. In the meantime, we still expect the development of new materials in the future to provide promising results for the treatment of collapsed tibial plateau fractures with bone grafting and filling.