Most adult TEFs have a history of trauma, especially high-energy trauma of a car accident, falls, and other injuries2, 8; the fractures are often accompanied by ligament and/or meniscus damage. The treatment plan in these patients is to provide elastic quality, tough stitching, and rigid hard metal fork-fixed avulsion bone and ligament reconstruction treatment. All treatment regimens attempt to rebuild the ACL tension and ligament proprioceptive function.
The tensile force of the native ACL 9, 10 during normal human activities is 500 N. The mean force of TEF is about 2500 N10, 11. According to the biomechanical properties of two mental buttons (Tightrope@ model), the mean vertical force in static load leading to failure measured 982 N and the mean anterior force in static load leading to the failure was 627 N12. The ultimate tensile force of this button system is strong enough to fix the fracture and restore ACL 13, 14. It also illustrates the biomechanical property, that is, the feasibility, of the button plates, which can be used to treat TEF.
The treatment plan includes conservative management for type 1 nondisplaced TEFs; surgical treatment is required for type 2 TEFs if the reduction is not anatomical7, 15, and for type 3 and type 4 fractures 16, 17. Successful arthroscopic reduction and fixation have been described in recent literature14.
With the use of arthroscopy in treatment, early activity and rapid recovery can be achieved, and the number of hospitalization days can be reduced. The treatment options reported so far include purse nails, cancellous bone screws, Kirschner wires, U-shaped nails, threaded rivets, sutures, and wire fixation. However, previous literature has reported that using suture fixation technology can help achieve good results.
Suture and rivet technology can achieve fixation of tibial intercondylar ridge fractures and reconstruction of anterior fork ligament tension7, 18, 19. It has been reported in the literature that suture and screw fixation techniques are very effective in fixing fractures and reconstructing anterior fork ligaments7, 18, 19. However, fixing the strength of these tools is not sufficient to favor the healing of fractures; most of them require a fixed full knee extension position and non-weight-bearing exercise for a long time, which leads to the knee joint adhesion and low activity. After treatment with these technologies, patients have a low quality of life and poor satisfaction.
We performed day-case, arthroscopic, double-button fixation technique treatment regimen; good function and relatively excellent knee joint scores were achieved, and this technique yielded the same or better results than other approaches5, 13, 20, 21. There have been reports of this treatment plan in the literature, but there are few evaluation indicators included9, 22. In this day-surgery study, the patients were treated with a double-button plate, which has both rigid and elastic characteristics. In this study, we adopted early function exercises and full weight-bearing after 2 days postoperatively. In contrast to the available literature, arthrofibrosis can be effectively avoided by continuously increasing the range of activities 20, and we suggest this aggressive regimen to secure the fixation (Fig. 9). At the last follow-up, the average knee mobility was about 130.45° (118–145°), which is comparable or better than previously reported13, 20, 21. We believe that early day-case arthroscopic surgery of TEFs achieves a better immediate surgical effect with more favorable cost-effectiveness.
At the same time, the SF-12 score (PCS, MCS) of the patients increased significantly. By this treatment, patients can perform knee joint functional rehabilitation exercises early, which can effectively reduce postoperative adhesion and stiffness caused by braking and increase the confidence of postoperative knee joint rehabilitation.
We believe that patients with TEF often have ACL injuries, such as traction, which may affect the stability of the knee joint after surgery2. In the previous literature, for TEF carina fractures, ACL injury was caused by traction during the fracture, resulting in more than 50% of the ACL injury, but this injury will not cause ligament rupture 2, 3, and no injury will lead to knee instability.
However, previous studies reported that 44% of patients with screw and wire fixation had physical instability and knee instability, and re-reconstruction of the ACL after this type of fracture was needed. It has been reported that the re-reconstruction rate of the ACL in adults is from 7% (5 years after surgery) to 12% (15 years after surgery)5, 6, 8. None of the patients needed ACL reconstruction in our study. The injury composition was different than that from the previous report, which may have influenced the result at the last follow-up. Before performing the fixation, the joint was thoroughly inspected to exclude ligament rupture by arthroscopy. The satisfaction rate was 81.8%, which was measured as suggested by Marsh6.
The knee flexion and extension activities of all patients were severely restricted before the operation. The imaging examination of all patients after 3 months showed that the anatomical reduction of the bone block and fracture healing were achieved. At the last follow-up, ADT was positive in three patients (3 knees, 13.63%), and Lachman test was positive in one patient (1 knee, 4.54%); the overall result was better than the previous examination of screw or suture fixation4. We considered that the reason for the positive ADT and Lachman test was the possibility of postoperative anterior fork ligament relaxation, and in 10 of 22 patients, there was also meniscus ligament compression and cartilage injury. The meniscus injury rate in our study is consistent with that reported in the literature, and the patients in this study were less involved in the vigorous knee joint sports, such as football or basketball and long-distance running. During the follow-up, none of the patients had obvious discomfort, and none of them underwent secondary knee arthroscopy.
It is well known that no matter whether incision or arthroscopic surgery is performed for tibial intercondylar ridge fractures, there are complications such as adhesion, fracture nonunion, dysfunction, loss, and relaxation 3, 13, 15, 20. Early rehabilitation exercises after fracture surgery can effectively restore knee function, but may also increase the risk of re-fracture, non-union fracture displacement, increased bleeding, increased inflammatory response, and repeated knee swelling13, 20. The recovery process of postoperative patients is different from previous similar reports9, 22. In this study, we included more evaluation indicators, and we asked patients to be fully weight-bearing on the second day after the operation. The functional exercise was within the adjustment range of the brace. We believe that early functional exercise is conducive to knee rehabilitation and improves knee mobility (ROM). Button steel plate fixation has the characteristics of elastic fixation and promotes fracture healing10, 11. Postoperative complications after treatment with this treatment protocol are significantly less common than previously reported in similar literature7, 12–16. In this study, there were two patients with knee joint extension loss at the last follow-up, which is similar to the previous literature; there was no joint release or joint ROM release under anesthesia. After being discharged from the hospital, the patient was urged to do strengthening functional exercise of the knee joint at home in a timely manner, and the restricted movement of the knee joint could be significantly improved. The proportion of patients with car accident trauma in this study is high, and there were often soft tissue injuries around the knee joint. These injuries led to easy adhesion, causing knee joint dysfunction. Patients undergoing day-case arthroscopic surgery do not need to wait long before operation, and these patients can exercise earlier.
The direction of the tunnel and the placement of intra-articular buttons may affect fracture healing and knee functional rehabilitation. The button plate requires anatomical reduction and fixation of the bone block and the combined force direction of the ACL for the nail path during treatment, which can achieve the maximum mechanical fixation direction. For the location, we suggest that the intra-articular plate be placed in the first 1/2 to the first 1/3 of the free bone to prevent “seesawing”; If the intra-articular plate is placed too far forward, such as 1/3 of the free bone, there will be “excessive reduction” in the front of the block and tilt in the back, resulting in poor reduction. Moreover, the internal and external diameters of the free bone fragments will be larger when the intra-articular plate is placed backward, which is more advantageous to prevent the bone fragments from breaking when drilling. In addition, the rotation of the intra-articular plate can be prevented by placing it in the anterior cruciate ligament. The design of the nail path of our patients’ bone block followed the force direction (Fig. 10). Femoral intercondylar presence is different in men and women, and the differences in the femoral intercondylar width were previously reported in the literature with the femoral intercondylar terminus average width of 14.5 mm–24 mm17, 20. However, the width of the intercondylar fossa in patients with osteoarthritis is narrower. The length of the long axis of the intra-articular loop plate is about 10 mm. We recommend that the long axis of the intra-articular loop plate should be parallel to the sagittal plane of the knee joint. This can effectively avoid the impact of the button plate on the narrower intercondylar fossa and reduce damage. We routinely sutured and reinforced the intra-articular button into the anterior ligament. However, during the postoperative follow-up, we found that the intra-articular button had rotated. This resulted in the risk of collision between the button plate and the intercondylar fossa. However, 16 patient follow-ups were found in the continuous presence of loop rotation button, intra-articular rectangular loop into a fixed position B type. One patient developed C-type and had no knee discomfort during follow-up. During the follow-up process, one patient had postoperative bouncing weakness and abnormal noise when the knee joint moved, but the knee flexion and extension function was good.
Button plates are used to treat TEF. We do not recommend secondary surgery to remove the internal fixation device because it is covered by soft tissue and ligament fibers after fracture healing. It is difficult to find and remove it under arthroscopy. Secondary surgery increases the costs and pain; however, if the intra-articular button body becomes loose in the knee, it must be removed.