Introduction

Tibial intercondylar spine fracture is considered anterior cruciate ligament inferior insertion avulsion fracture1. In recent years, with the increase of various sports injuries and traffic accidents, intercondylar ridge fracture has gradually become a common intra-articular fracture of the knee, and the incidence rate is getting higher and higher2. In tram accidents, knee valgus or rotational stress and hyperextension of the knee are likely to cause intercondylar ridge avulsion fractures, which account for 2–5% of all knee injuries. The injury mechanism is mostly caused by motor vehicle accidents, sports injuries, hyperextension, rotation of the knee during falls, or direct violence. During the injury process, the traction of the anterior cruciate ligament will cause avulsion and displacement of the fracture. Intercondylar ridge fracture were first described by Poncet as early as 1875. and the classic X-ray classification system was proposed by Meyers and McKeever3 which was updated and improved by Zaricznyj in 1977 and is still used today4.

Treatment of different types of intercondylar ridge fractures: For type I fractures, conservative treatment with plaster immobilization and regular follow-up is generally recommended because the fracture is relatively stable and the tension of the anterior cruciate ligament is acceptable. Type II and III fractures are prone to secondary meniscus and cartilage damage and accelerated joint wear and degeneration due to fracture displacement, loss of tension of the anterior cruciate ligament, and instability of the knee joint. Surgical treatment is generally required. The surgical methods mainly include traditional open reduction and internal fixation or arthroscopic reduction and internal fixation. Open reduction and internal fixation is a relatively old surgical method. With the continuous development of arthroscopic technology and the concept of small incisions, early and rapid recovery and return to sports, arthroscopic minimally invasive surgery has gradually become the mainstream. Arthroscopic surgical methods include wire fixation, screw fixation5 and suture fixation6. Among them, Orthcord sutures have better flexibility than wires and screws, and there is no need to remove the implants again after surgery. The non-metallic material does not affect security checks and imaging examinations such as MRI in normal life.

Data and methods

General data

This study selected 80 patients with intercondylar eminence fractures admitted to our hospital from October 2020 to March 2023, and compared and analyzed different fixation methods to explore the effectiveness and economic value of Orthcord suture fixation.All patients underwent knee joint X-ray, CT and MRI examinations. This study grouped the included patients according to the surgical method they underwent. At the beginning of the analysis, all patients had undergone surgical treatment without additional intervention. Inclusion criteria: ① Patients aged>18 years and epiphysis closed; ② Clear diagnosis of Meyers-Mckeever II and III type fractures of the tibial intercondylar eminence; ③ Lachman test and anterior drawer test were positive; ④ The patient agreed to surgical treatment or actively cooperated and signed an informed consent form. Exclusion criteria: ① Old fractures with a time interval from injury to surgery greater than 14 days.②Patients with fractures around the knee joint (femur, patella, etc.) and vascular and nerve injuries ③ Patients who were lost to follow-up for less than 3 months ④ Patients with posterior cruciate ligament rupture or medial collateral ligament rupture;

All surgeries for this study were performed by the same team, and the study was approved by the ethics committee of this institution. All methods were carried out in accordance with relevant guidelines and regulations.

Pre-treatment evaluation

Among all patients, 57 were injured in traffic accidents, 10 were injured in slips or falls, 8 were injured in sports such as basketball, football, and badminton, and 5 were injured in falls. The 80 patients were divided into three groups according to the treatment they received: high-strength suture Orthcord group (n = 30): 17 males, 13 females, 11 Meyers-Mckeever type II, 19 type III, wire group (n = 26): 14 males, 12 females, 12 Meyers-Mckeever type II, 15 type III; screw group (n = 24): 13 males, 11 females, 8 Meyers-Mckeever type II, 16 type III. The general data of the three groups of patients are shown in Table 1.The tibial intercondylar eminence is the attachment point of the anterior cruciate ligament to the tibia. There is more blood accumulation in the knee joint after fracture, and the knee joint is swollen7. Acute injuries usually cannot use scoring scales to assess activity levels. The knee joint is usually in a slightly flexed position, Therefore this study used X-rays (anteroposterior and lateral X-rays of the knee joint, Fig.1a and b) to determine the displacement of the fracture and 3D CT to provide a more accurate fracture type (Fig. 2a–c), Magnetic resonance imaging is used to assess the tension of the patient’s cruciate ligament. At the same time, imaging examinations are used to exclude patients with other injuries (such as the medial collateral ligament, posterior cruciate ligament, etc.).

Table 1 Comparison of general data of patients in the three groups f = female M = male.
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Fig. 1
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A female patient was hospitalized for tram injury. Her knee joint was obviously swollen. X-ray examination of the knee joint showed a fracture of the lower insertion point of the anterior cruciate ligament and a raised fracture fragment (the red arrows in the figure show the intercondylar ridge fracture a and b).

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Fig. 2
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In addition to X-rays, intra-articular fractures usually require CT three-dimensional reconstruction to further clarify the fracture situation. Three-dimensional reconstruction can show displacement of the lower insertion point of the fracture.

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Surgical method

Orthcord suture group

A conventional approach to the knee joint (anterolateral and anteromedial) was Established, and the blood that blocked the vision in the Suprapatellar bursa, synovium and infrapatellar fat pad was cleaned using the arthroscopic power system. After the vision was clear, the blood scab and underlying soft tissue at the intercondylar ridge fracture were cleaned to expose the fracture fragments and bone bed. The fracture fragments were reduced with curved forceps and probe hooks, and 1 to 2 1.0 Kirschner wires were percutaneously inserted to reduce and fix the fracture fragments. A small incision was made below the tibial tuberosity, and two 2.0 Kirschner wires were inserted using the ACL reconstruction locator to Establish bone tunnels on the anteromedial and anterolateral sides of the bone bed (Fig.3a and b). The outer openings of the bone tunnels were all located on the medial side of the tibial tuberosity, and the distance between the bone tunnels was greater than 1 cm. Arthroscopic approach, using right-angle clamps through the frontal approach of the arthroscope, fold one end of an orthcord high-strength suture in half and place it in the joint cavity, use right-angle clamps to fix it in an “8” shape around the anterior cruciate ligament (Fig. 3a and b), place both ends of the high-strength suture (Fig.3c and d), insert a strand of steel wire Lasso through the bone tunnel made by the previous 2.0 Kirschner wire, and pull out the tail end of the orthcord high-strength suture through the steel wire Lasso, then stretch the knee to help reduce the fracture, and after the fracture ends are adjusted in place, tighten and knot the suture at the external opening to fix it (Fig.4a-g). After firm fixation, observe whether there is any impact under the arthroscopy, move the knee joint in the entire range of motion, and use the Lachman test to evaluate the stability of the knee joint.(video 1).

Fig. 3
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As shown in Figure a, an arthroscopic approach is established to clear the blood in the joint to expose the fracture fragment and thoroughly clean the bone bed. b, an anteromedial and anterolateral bone tunnels are established under the guidance of the locator. Figures c and d show the introduction of the suture through the right-angle clamp and the fixation of the fracture fragment in the shape of"8"after bypassing the anterior cruciate ligament.

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Fig. 4
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Cleaning the blood clots around the fracture, the ligament-connected fracture fragment was seen to be lifted up (a and b), which was consistent with the preoperative MRI examination results. (The red arrow in c shows that the anterior cruciate ligament is loose, the fracture fragment is lifted up, and the ligament loses tension) During the operation, Kirschner wires were used to temporarily fix the fracture fragments (d) to maintain a stable position, and an anterior cruciate ligament locator was used to create a tibial bone tunnel (e). After the bone tunnel was made, Orthcord sutures were introduced and cross-fixed. The tension of the anterior cruciate ligament was restored (f). The wound was minimally invasive and beautiful. The first dressing change after the operation was minimally invasive and did not require suture removal. It was beautiful and did not require suture removal (g).

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Steel wire fixation group

Fracture reduction and temporary fixation are the same as above. Double-strand steel wires are introduced through the tibial bone tunnel and then pulled out from the arthroscopic approach. The outer wire is used as a guide to pull out the inner double-strand steel wire. After the fracture fragment position is properly adjusted to a satisfactory level and the wire tension is adjusted, it can be tightened. The wire tension should be moderate to prevent the wire from breaking due to excessive pressure and excessive cutting of the fracture fragment.

Hollow screw group

Fracture reduction is the same as above. Two small incisions are made on the inner and outer sides of the patella, and the Hollow screw guide pin is inserted and fixed through the parapatellar incision. The guide pin positions are more than 4 mm apart, and there is enough space to insert the Hollow screw. After confirming that the fracture fragment is in a good position, screw in the Hollow pressure screw and use a gasket if necessary.

Postoperative rehabilitation

All three groups of patients were fixed in the straight position with braces immediately after surgery. Five days after surgery, after the cotton leg pressure bandage was removed, a knee flexion functional exercise was performed. Knee flexion functional exercise was performed again in the second week after surgery (twice the knee flexion reached about 90°). Starting from 3 weeks after surgery, knee flexion exercises were performed every 2 days, and each training increased the knee flexion angle by about 5° compared with the previous training, and the knee flexion angle increased by 10 degrees per week. Within 6 weeks after surgery, crutches were not used to bear weight on the affected limb. Six weeks after surgery, the patient gradually walked with weight under the protection of the brace, and the brace was completely removed after 3 months.

Postoperative follow-up observation and clinical evaluation

The patients were reexamined at 1, 2, 3, and 6 months after surgery, and X-ray or CT three-dimensional reconstruction was performed to evaluate the fracture healing, MRI examination was performed to evaluate the tension of the anterior cruciate ligament(Figures 5a - d), and the changes in the angle of the patient’s knee joint were recorded in time. Six months after surgery, the Lysholm score was used to objectively evaluate the patient’s recovery, and the Lachman test was performed to determine the stability of the anterior cruciate ligament.

Fig. 5
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Postoperative knee joint MRI (a and b) was performed. MRI showed that the tension of the anterior cruciate ligament was significantly restored compared with that before the operation (indicated by the red arrow: a shows that the anterior cruciate ligament lost tension, and b shows that the ligament tension was restored after fixation) Postoperative review of the knee joint CT three-dimensional reconstruction showed that the fracture was well reduced c was the preoperative CT, and postoperative d showed that the fracture was well reduced.

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Statistical methods

The data collected in the study were analyzed using spss 26.0 software, and the graphs were drawn using GraphPad Prism 8 software. The measurement data such as age, weight, time and score, as well as the patient’s hospitalization time, operation time, intraoperative blood loss, postoperative knee function score (Lysholm score of the knee joint 3 months and 1 year after surgery) were expressed as ‾x ± s and analyzed by variance. The measurement data such as gender and recurrence rate were tested by chi-square test. and P<0.05 was considered statistically significant.

Results

There was no statistical difference in the general data of all patients. All patients were followed -up for 1 year after surgery. and bone union was achieved without infection, displacement, or bone malunion. The Lachman test and drawer test were negative after surgery. The hospitalization time of the wire group was (11 ± 1.02) days, the screw group was (11.58 ± 1.61) days, and the Orthcord suture was shortened to (10.03 ± 1.07) days. The difference between the three groups was statistically significant (P < 0.05). At the same time, the cost of the Orthcord suture surgery (1310.7 ± 0.29) $ was significantly lower than that of the other two groups (P < 0.05). In terms of operation time, the suture group (68.13 ± 1.11 min) was significantly shorter than the wire group (76.76 ± 11.57 min) and the screw group (90.62 ± 1.99 min) (P < 0.05). In the follow-up, the score of Orthcord suture at 3 months after surgery (94.07 ± 2.72 points) was better than that of the wire group (90.23 ± 5.23 points) and the screw group (90.37 ± 5.41 points); the difference was statistically significant (P < 0.05). However, there was no statistically significant difference in the Lysholm score among the three groups of patients at 12 months after surgery (96.26 ± 1.89, 96.33 ± 2.44, 97.3 ± 1.70) (P > 0.05). Three months after surgery, the range of motion of the knee joint in the Orthcord suture group (124.8°±7.2°) was significantly better than that in the screw group (105.7°±9.3°) and the wire group (112.4°±8.6°) (P<0.05). However, there was no statistically significant difference in the Lysholm score of the three groups of patients 1 year after operation (96.26 ± 1.89, 96.33 ± 2.44, 97.3 ± 1.70) (P>0.05).Similarly, there was no significant difference in the range of knee motion among the three groups of patients 1 year after surgery (135.1°±4.2°), (134.6°±4.8°), and (136.3°±3.5°) (P>0.05).See Table 2.Late fixation fracture and chronic pain complications occurred in both the wire and screw groups, but not in the suture group. (P<0.05).See Table 3.

Table 2 Comparison of intraoperative and postoperative conditions among the three groups. F=(ANOVA).
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Table 3 Comparative analysis of postoperative complications.
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Discussion

Tibial intercondylar eminence fracture, also known as anterior cruciate ligament (ACL) avulsion fracture, accounts for 2–5% of all knee injuries in children and 3% of all ACL injuries in adults. However, with the popularization of electric vehicles and frequent traffic accidents in recent years, the number of adult intercondylar eminence fractures has been increasing year by year8.Our study observed the postoperative recovery of patients who were fixed with screws, wires, and Orthcord sutures. The results of a 1-year follow-up showed that after the fracture was completely healed, the three did not show significant statistical differences in knee function scores. However, the Orthcord suture group showed obvious advantages in terms of operation time, surgical costs, surgical trauma, and short-term recovery.In previous studies, a biomechanical study by Noyes FR9 found that the tibial intercondylar eminence is a bony protrusion between the articular surfaces of the medial and lateral condyles of the tibia, and the anterior and posterior positions of the protrusion are the attachment sites of the meniscus and anterior cruciate ligament, respectively.

Traditional surgery for intercondylar ridge fractures is performed through open reduction and internal fixation. Arthroscopically assisted treatment can be traced back to the 1980 s, and has become the mainstream treatment method as arthroscopic technology continues to develop and mature10,11. Current treatment methods include Kirschner wires, metal screws, wire anchors, gussets, and various bioabsorbable implants (absorbable screws, sutures, etc.); there are many types of fixation techniques, each with its own advantages and disadvantages, and there is currently no gold standard for surgical treatment of these injuries. Although there are many controversies about the preferred method for treating type II and type III fractures, the main reason is the difference in the choice of fixation12.

Traditional surgery for intercondylar ridge fractures is open fracture reduction and internal fixation. Arthroscopically assisted treatment dates back to the 1980s.With the continuous development and maturity of arthroscopic technology, it has become the mainstream method for treating intercondylar ridge fractures11. Current surgical methods for treating intercondylar ridge fractures include Kirschner wires, metal screws, wire anchors, and various biomaterials, such as Orthcord sutures and Ethicon sutures12.H Najdi13, et al. showed that screws provide good stability in the treatment of intercondylar ridge type II and III bones. Previous studies14 have shown that steel wires are also very stable in fixing intercondylar ridge fractures. We found that when using screws to fix fracture fragments, it is sometimes difficult to achieve a satisfactory angle of screw insertion during surgery. Any deviation in the angle may lead to a decrease in fixation strength. Therefore, a lot of time is required to locate the angle during surgery. This is improved when using steel wire fixation, because the steel wire can be bent to better fix the fracture fragment. However, this operation also inevitably increases the operation time. Therefore, in our study, the operation time of the screw group and the steel wire group was significantly longer than that of the Orthcord suture group15. Of course, some studies have used simpler Kirschner wire fixation16,17,18 but studies have shown that Kirschner wires cannot firmly fix comminuted and small fracture fragments. In the long term, they cannot be used as the preferred method due to the risk of infection, loosening, and dislocation of the tail end of the Kirschner wire.

In the current study, all patients showed significant improvement in follow-up results compared with preoperative radiological or clinical examination. This supports the effectiveness of the Orthcord suture technique in repairing adult tibial intercondylar eminence fractures. Although different methods have produced good clinical and radiological results, suture fixation can reduce the degree of iatrogenic trauma19,20,21,22 because there is no secondary surgery to remove the internal fixation, and studies have shown that at the same time, in our study, there were 2 cases of internal fixation breakage in the wire group, which is an unavoidable situation when using wire fixation, and the cutting force generated by the wire on various parts of the knee joint can directly affect or limit the patient’s early postoperative activities, and even cause traumatic arthritis8. The knee joint is a multi-activity weight-bearing joint, and the fracture will inevitably produce stress on the wire during growth, causing metal fatigue to a certain extent, and eventually leading to the breakage of the internal fixation. There is no such complication for patients using the Orthcord suture. In addition, in terms of treatment costs, both wires and screws need to be removed secondary, especially the removal of screws requires the help of arthroscopy, which ultimately leads to costs far higher than the Orthcord suture group. Orthcord sutures are sterile synthetic sutures made of polyethylene and PDS, which have good biocompatibility. They are not only high-strength and wear-resistant, but also have low cutting force on soft tissues, thus ensuring the stability of the bone fragment during postoperative knee flexion and extension exercises2.As a hybrid braided non-absorbable suture, Orthcord suture has unique biomechanical properties that make it perform well in the fixation of anterior cruciate ligament inferior insertion fractures. The elastic modulus of Orthcord suture is closer to that of natural ligament tissue, which enables it to better simulate the mechanical behavior of the ligament during fixation23. In biomechanical testing, the elastic modulus of Orthcord suture is between the high elastic modulus FiberWire and the low elastic modulus PDS. This moderate elastic modulus allows it to provide sufficient initial stability when fixing anterior cruciate ligament inferior insertion fractures without causing bone resorption or stress shielding due to excessive stiffness24.

In terms of stability, the biomechanical stability of the suture group was close to that of the screw group, but the functional recovery was better, which seems to be different from the conclusion of the meta-analysis by Stokes et al. (2024)25. In the operation, we used a double-strand suture to bypass the ligament “8” suture fixation, and at the same time, the method of secondary pressure fixation in the front made up for the defect of insufficient shear resistance of the suture. However, most of the literature included in the Stokes study used a single-line ligation technique, which is prone to secondary displacement of the bone due to stress concentration. In addition, screw fixation is prone to bone fragmentation, while sutures can avoid such complications by bypassing the periphery of the bone block through “soft fixation”. The proportion of type III fractures in the Stokes study was low (about 45%), which may have magnified the advantages of screws.

In addition, in terms of surgical technique, the key requirement for the reduction of intercondylar spine fractures is not to destroy the posterior fibers of the fracture fragment. When fixing, it is only necessary to press down the front end of the tilted part to achieve the requirements of anatomical reduction. During the reduction process, it is often found that the anterior horn of the meniscus or the transverse ligament of the knee is stuck in the gap between the broken ends of the intercondylar spine fracture. At this time, the transverse ligament of the knee or the meniscus should be properly handled. In most cases, the transverse ligament of the knee needs to be surgically removed so that the bone bed can be fully exposed to fully expose the surgical field for easy reduction. Intercondylar spine fractures are rarely combined with anterior cruciate ligament rupture or tibial plateau fracture. Anterior cruciate ligament injuries are mostly partial ruptures. For those with anterior cruciate ligament ruptures, primary or secondary ligament reconstruction should be performed according to the ligament rupture. For those with tibial plateau fractures, the tibial plateau fracture should be reduced at the same time, and then the intercondylar spine fracture should be reduced and fixed internally. Compared with other surgeries, sutures do not need to be pre-bent, which greatly shortens the operation time and can better restore the tension of the anterior cruciate ligament26,27. Currently, many surgical methods have been developed for the treatment of tibial intercondylar eminence fractures28,29 all of which can restore the anatomical structure of the intercondylar ridge fracture and restore the tension of the anterior cruciate ligament. However, there are still many problems to be solved, such as knee extension dysfunction and postoperative anterior cruciate ligament laxity30.

This surgery has many advantages, including: arthroscopic surgery has lower morbidity and faster recovery compared to open surgery. Compared with screw and wire fixation, this technique uses suture fixation, eliminating the possibility of secondary surgery to remove traditional internal fixators. This technique fixes the lower end of the anterior cruciate with better stability and minimizes ligament creep. It also eliminates physical damage, implant irritation, and impact caused by poor fixation position caused by internal fixators.

However, this study also has some limitations. First, as a retrospective analysis, the current study only provides limited clinical diagnosis and treatment evidence and lacks mechanical analysis. Second, the sample size is relatively small, and the study will continue and extend the follow-up time. Third, this study did not include type IV comminuted fractures and small avulsed bone fragments, which still need further supplementary research.In subsequent studies, we will continue to follow up for a long time and observe the patients’ knee joint function, fracture healing, and possible delayed complications. Regular knee joint function scores, imaging examinations, and quality of life assessments will be performed on patients. At the same time, combined with biomechanical experiments, in-depth research will be conducted on the fixation strength, stability, and stress distribution of surrounding tissues of different fixation materials (such as wires, screws, and sutures) at the lower end of the ACL. The results of biomechanical research provide a theoretical basis for clinical selection of the most appropriate fixation method. Finite element analysis technology will be further used to simulate the mechanical behavior of different fixation methods in ACL lower end fractures and evaluate their stability and reliability under different load conditions.

Conclusion

Using Orthcord sutures to treat intercondylar ridge fractures under arthroscopy can shorten the hospital stay and operation time, and greatly reduce the cost of hospitalization. It can achieve better short-term (3 months) recovery effect on the basis of avoiding secondary surgery, and the failure rate of the Orthcord suture group was lower than that of the traditional screw and wire group at the final full weight-bearing recovery.