We retrospectively studied 108 Schatzker II tibial plateau fractures and found that lateral meniscus injury can be predicted by preoperative X-ray measurement, when TPW > 6.5mm, LPD > 9.1mm, or CALF > 20.3°, highly indicating the possibility of lateral meniscus tear.
Tibial plateau fractures often present with swelling and pain in the knee joint, accompanied by limited joint mobility [6, 7]. This poses a certain obstacle for doctors during clinical examinations, as it is generally difficult to determine the presence of meniscus injury through physical examination. The utilization of MRI in the diagnosis of soft tissue injuries presents certain advantages. In cases of tibial plateau fractures, MRI imaging is frequently employed to assess potential soft tissue damages including menisci and ligaments [11]. However, MRI examination also has certain limitations. Some patients have metal implants in their body, such as pacemakers, artificial joints or orthodontic equipment, which can interfere with MRI images or even cause harm to patients [12]. Therefore, MRI is generally not recommended in patients with these devices in the body. MRI examination often requires a relatively long period of time, and some patients may not be able to remain still and comfortable in a cramped MRI machine. MRI may not be appropriate, especially in patients with extreme anxiety or severe claustrophobia. MRI is often relatively expensive, which can be a burden on health insurance and out-of-pocket patient payments. X-ray examination is the most commonly used clinical examination method, and almost all fracture patients need X-ray examination before operation [13]. Therefore, by analyzing the preoperative X-ray morphological characteristics of Schatzker Ⅱ tibial plateau fractures, we found that when TPW > 6.5mm, the sensitivity was 42.4% and the specificity was 91.8% for lateral meniscus tear. When LPD > 9.1mm, the sensitivity was 69.5% and the specificity was 65.35% for lateral meniscus tear. When CALF > 20.3°, the sensitivity and specificity of lateral meniscus tear were 50.85% and 81.6%, respectively.
The mechanism of Schatzker Ⅱ tibial plateau fracture is that the knee joint is subjected to the dual effects of axial force and valgus stress at the same time. The lateral femoral condyle impinges on the lateral tibial plateau under the effect of violence, resulting in split and compression depression of the lateral tibial plateau [14–16]. Because the body of the lateral meniscus is closely connected to the lateral plateau through the joint capsule, the anterior horn is connected to the medial meniscus through the transverse ligament of the meniscus, and the posterior horn is connected to the posterior condyle of the femur through the meniscofemoral ligament, it is easy to combine meniscus injury when the lateral tibial plateau fracture occurs[17].In our cohort, the incidence of Schatzker type II tibial plateau fracture with lateral meniscus tear was 54.6% (59/108) during arthroscopic exploration. Gardner et al. [4] used MRI to evaluate tibial plateau fractures with lateral meniscus injury and found that the injury rate was as high as 91%. However, MRI examination may be interfered by intra-articular hematoma, resulting in a certain false positive rate. Parkkinen et al. [9] found that there was a large difference between the preoperative evaluation of soft tissue injury by MRI and the confirmation of meniscus tear during arthroscopy, which suggested that there was a problem of excessive diagnosis by MRI. Therefore, in our study, we used arthroscopic exploration to confirm the presence of meniscal tears. In this study, meniscocapsular separation accounted for 66% (39/59) of all types of tears, which was similar to the results of previous studies. Stahl D et al. [18] reported that 83% of Schatzter Ⅱ tibial plateau fractures combined with lateral meniscocapsular separation.
Previous studies have shown that meniscus injury is the most common type of soft tissue injury associated with tibial plateau fractures [19]. Wang et al. [20] conducted a study on 54 cases of tibial plateau fractures, and the results showed that the incidence of Schatzker IV combined with soft tissue injury was 85.7%, and the incidence of Schatzker II combined with soft tissue injury was 74.1%. Among all types of soft tissue injury, the incidence of meniscus injury was the highest (55.6%). The study also suggested that when TPW > 7.4 mm, LPD > 5.6mm, the risk of meniscus injury increased significantly. Chang et al. [21] used CT and arthroscopy to find that among 102 patients with tibial plateau fractures (Schatzker II-IV), Schatzker II accounted for 32% (33/102). When LPD > 6.3mm, the risk of lateral meniscus injury is greatly increased. Durakbasa et al. [22] performed open reduction and internal fixation on 20 patients with Schatzker Ⅱ tibial plateau fractures, they found that when preoperative TPW > 10mm and LPD > 14mm, the risk of lateral meniscus tears would be significantly increased. Kolb et al. [23] studied 55 patients with Schatzker I-III plateau fractures (50 patients with Schatzker II fractures) and proposed that for every 1 mm increase in TPW, the probability of lateral meniscus injury would increase by 40%. Our study on 108 Schatzker II tibial plateau fractures found that when TPW > 6.5mm, LPD > 9.1mm or CALF > 20.3°, the risk of lateral meniscus tear was significantly increased. Most of the previous studies focused on the effect of TPW and LPD on meniscus injury, but few studies reported the effect of CALF on meniscus injury. In fact, CALF indirectly reflects the amount of energy absorbed during knee injury. Theoretically, the larger the CALF, the greater the violence on the knee joint, and the greater the risk of lateral meniscus tear.
The meniscus is a cartilage structure located between the femur and the tibial plateau, which plays a role in buffering pressure, transferring load, and stabilizing the knee joint. Meniscal injuries were classified into three levels, and the first level meniscus injury is usually mild and may be some irritation or inflammation, but there is no true tear or rupture, this level of injury can often be treated with rest and physical therapy. The second level meniscus injury usually involves a partial tear of the meniscus that remains in its normal position, this may require further conservative treatment, such as physiotherapy or anti-inflammatory drugs, to aid recovery. The third level meniscus injury indicates that the meniscus has been completely torn, and a third level meniscus injury usually requires surgical repair, usually performed using knee arthroscopic techniques [24]. In this study, we used arthroscopy for intraoperative exploration. If there was a meniscus tear, suture or plasty was performed immediately under arthroscopy. In an early clinical study, Vangsness et al. [25] performed arthroscopy on 36 patients with tibial plateau fractures and found that 47% of the patients had meniscal tears. Open meniscal suture was performed during internal fixation, and partial meniscectomy was performed in 12 patients with refractory meniscal. No traumatic arthritis occurred. Ruiz-Iban et al. [26] conducted a long-term follow-up study on 51 patients with tibial plateau fracture, of which 15 patients with meniscus injury underwent meniscus suture repair combined with fracture reduction and internal fixation, and were followed up for at least 4 years. There was no significant difference in the clinical outcome between the meniscus injury group and the tibial plateau fracture group without meniscus injury. Therefore, it is very important to repair the meniscus in the first stage of tibial plateau fracture combined with meniscus injury.
In addition, this study has some limitations. All parameters were measured manually using PACS system, which inevitably led to some measurement errors. As a single-center retrospective study, the sample size is limited; future studies should expand the sample size and conduct multi-center studies to make the data more representative. Only the relationship between the X-ray characteristics of Schatzker II tibial plateau fracture and the lateral meniscus injury was explored. Further studies should be conducted to investigate the relationship between the characteristics of other types of tibial plateau fracture and the medial and lateral meniscus injuries.