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To evaluate the clinical outcomes for arthroscopic treatment of acute posterior cruciate ligament (PCL) avulsion fractures with adjustable-loop cortical button fixation device.
Methods
Patients with PCL tibial avulsion fractures treated with an adjustable-loop cortical button fixation device between October 2019 and October 2020 were retrospectively identified. Patients with type 1 were treated using plaster fixation as a conservative treatment, whereas patients with type 2 and 3 with displacement were treated using an arthroscopic adjustable-loop cortical button. Operating time, incision recovery, complications, and postoperative fracture healing time were monitored. All patient follow-up was done at 12 months’ postoperatively. Lysholm Knee Score and the International Knee Documentation Committee score were used to assess knee function.
Results
A total of 30 patients were included in the study (20 male/10 female; mean age 45.5 years, range 35-68 years). The mean operative time was 67.5 minutes (range: 50-90 minutes). The postoperative incision healed at stage A without complications, such as medically induced vascular nerve injury, intra-articular hematoma, or infection. All 30 patients were tracked postoperatively for 12 to 14 months, with a mean follow-up period of 12.6 months. The Lysholm knee function score was 45.93 ± 6.15 before surgery and 87.10 ± 3.71 at 12 months after surgery, and the International Knee Documentation Committee score was 19.27 ± 4.40 before surgery and 95.47 ± 1.87 at 12 months after surgery, with a statistically significant difference.
Conclusions
The treatment of PCL avulsion fractures with arthroscopic adjustable-loop cortical button fixation is easy to perform and shows good clinical results in our study.
Level of Evidence
IV, therapeutic case series.
Posterior cruciate ligament (PCL) avulsion fractures are becoming increasingly common in Asian countries as the result of the growing number of 2-wheeled vehicle accidents.
The PCL originates from the lateral side of the medial femoral condyle and terminates 3 mm proximal to the articular cartilage margin of the tibial condyle.
The PCL has been established to be an important knee stabilizer, primarily preventing excessive posterior displacement of the tibia relative to the femur. PCL injuries without fracture displacement can be treated conservatively without operation. In patients with complete fractures with displacement, prompt surgical repositioning and internal fixation are necessary. Because of the pulling of the PCL, the bone avulsion fragments tend to separate at an early stage and the soft tissue tends to become embedded in the gap between the bone fragments and the tibial fracture bed, making repositioning and fracture healing difficult. This injury can result in knee instability and possible long-term degeneration.
The principles of surgical treatment for PCL avulsion fractures are to achieve anatomical repositioning and to restore ligamentous tension. There are currently 2 main types of surgery: (1) open reduction with internal device through a posterior approach; and (2) arthroscopic treatment.
Displaced posterior cruciate ligament avulsion fractures: A retrospective comparative study between open posterior approach and arthroscopic single-tunnel suture fixation.
Although traditional open surgical fixation for PCL avulsion fractures has achieved satisfactory clinical results, it is associated with high risks and complications in open surgery resulting from the proximity of complex popliteal neurovascular structures, which require long skin incisions and can lead to muscle and joint capsule damage or joint contractures. In recent years, the advantages of minimally invasive procedures have led to the widespread use of arthroscopic surgery. The advantages of arthroscopic treatment over conventional treatment include the diagnosis and treatment of concomitant meniscal injuries and cartilage injuries among others, which often are associated with PCL avulsion fractures. A variety of arthroscopic fixation implants have been reported, such as hollow screws,
Arthroscopic fixation for tibial eminence fractures: A clinical retrospective study of cannulated screws versus transosseous anchor knot fixation techniques with suture anchors.
All-suture anchors versus metal suture anchors in the arthroscopic treatment of traumatic anterior shoulder instability: A comparison of mid-term outcomes.
Clinical outcomes of acute displaced posterior cruciate ligament tibial avulsion fracture: A retrospective comparative study between the arthroscopic suture and EndoButton fixation techniques.
in 2010 and has gradually been applied worldwide as a treatment for the fixation of PCL avulsion fractures. The purpose of this study was to evaluate the clinical outcomes for arthroscopic treatment of acute PCL avulsion fractures with an adjustable loop cortical button fixation device. We hypothesized that this method would provide satisfactory results with fewer complications and would have the same fixation effect as the traditional open surgery.
Methods
Patients with unilateral knee PCL avulsion fractures treated with an adjustable-loop cortical button device in our hospital from October 2019 to October 2020 were identified. Approval from the ethics committee and the institutional review board were obtained for this study. The inclusion criteria were avulsion fractures of PCL with obvious tibial displacement confirmed by radiography, computed tomography, and other imaging examinations; fracture within 2 weeks; and arthroscopy performed with adjustable-loop cortical button fixation (TightRope; Arthrex, Naples, FL) device. The exclusion criteria were type I avulsion fractures according to White et al.
that could be treated conservatively; inability to carry out rehabilitation training due to severe complications; and lost or incomplete data of postoperative follow-up. The surgical plan was made preoperatively, with an assessment of the Lysholm Score and International Knee Documentation Committee (IKDC) score. The procedures were all performed by the same senior surgeon (Fig 1).
Fig 1A 50-year-old male patient with avulsion fracture of left posterior cruciate ligament on computed tomography and 3-dimensional reconstruction.
The patient was administered subarachnoid anesthesia in the supine position. A tourniquet was placed on the proximal thigh, and the traditional high anteromedial and anterolateral approach was used for arthroscopic exploration. If there is meniscus injury, meniscus plasty should be performed first. The arthroscope was placed in the posterior chamber from the anterolateral approach between the PCL and the medial condyle of the femur, and the low posteromedial approach and high posteromedial approach were established under arthroscopic monitoring. The arthroscope was entered through the high posteromedial approach and the planer entered through the posterior chamber through the low posteromedial approach to remove hematoma and other soft tissues near the PCL stop and identify the end of the fracture. The angle of the PCL locator (Karl Storz, Tuttlingen, Germany) was set to 50°. The posterior chamber was entered through the anterior medial approach, and the tip was located in the center of the avulsed bone mass. The fracture block was reduced by posterior and anterior stress, and a 2-cm incision was made at the medial 2 cm of the tibial tubercle. The Kirschner wire was inserted into the incision through the PCL locator, and the distal end of the Kirschner needle was pierced from the center of the PCL fracture block under arthroscopic supervision. The PCL locator was removed and replaced with a 4.5-mm hollow guide needle to establish a bone tunnel. Once the bone fragment cortex was penetrated, the guide line was sent through the small incision in the medial side of the tibial tubercle through the distal end of the bone tunnel, and the guide line was pulled out through the low posterior medial approach with another grip clamp. The guide needle and hollow drill were removed, and the lead was pulled forcefully. Under the arthroscopic monitoring of the high posterior portal, the strip button was pulled out from the proximal end of the bone tunnel, and the button is flipped by a slight pull on the other traction wire. Then, the distal end of the device was pulled, and the strip button was tightened and pressed on the PCL fracture block to complete the reduction. Then, the knee was flexed 90°, the tibial tail line was tightened, and the knot was fixed when the distal circular button was seen close to the surface of tibia. The front- and back-drawer test and Lachman test were performed (Fig 2, Fig 3, Fig 4, Fig 5).
Fig 2(A) The arthroscope is entered into the posterior chamber from the anterolateral approach between PCL and the medial condyle of the femur, and the low posteromedial approach and high posteromedial approach were established under arthroscopic monitoring. (B) The PCL locator is set. (C) The guide line is sent through the incision and pulled out through the low approach. (D) The button. (PCL, posterior cruciate ligament.)
Fig 3(A) Set approaches under the arthroscope. (B-C) The PCL locator was set. (D) Under the arthroscopic monitoring of the high posterior internal approach, the strip button was pulled out from the proximal end of the bone tunnel, and the button was flipped by a slight pull on the other traction wire. (PCL, posterior cruciate ligament.)
The knee joint was fixed with hinge brace after operation, and the isometric contraction of quadriceps femoris and straight leg raising exercises were encouraged as soon as possible. On the first day after operation, the hinge brace could be turned to the ground at 0° position. One week later, the knee joint began to move passively under the protection of the brace. The passive flexion could not exceed 30° within 4 weeks, and the passive flexion increased gradually after 4 weeks. Maximum flexion was reached at 12 weeks. Part of the affected limb was loaded within 8 weeks, then the weight was carried completely, and the knee joint brace was used for protection for 3 months. After 12 weeks, the knee joint moved freely and strength exercises were performed at the same time. Postoperatively, patients were followed up regularly to understand the motion stability and flexion and extension of the knee joint. The overall functional recovery of the affected limb was evaluated according to the Lysholm knee joint score and IKDC score standard 12 months after operation (Fig 6). We also use low molecular weight heparin sodium from the first postoperative day until the patient is discharged from the hospital to prevent deep venous thrombosis.
Fig 6Three-dimensional reconstruction images after operation.
The SPSS 26.0 statistical software package (IBM Corp., Armonk, NY) was used for analysis. Measurement data are expressed by mean ± standard deviation (x ± s). Paired t-test was used for comparison between groups, and the difference was statistically significant (P < .05).
Results
A total of 30 patients met our inclusion criteria (Table 1). Of these patients, 4 had meniscus tear and they all underwent partial meniscectomy. Operation time was 50 to 90 minutes, with an average of 67.5 minutes. All the incisions healed in stage A after operation, and there were no complications such as vascular and nerve injury, intra-articular hematoma, or infection. All patients with surgery were followed up for 12 to 14 months (mean 12.6 months). Radiographic examination showed that all the fractures healed in stage A without further displacement. Knee flexion was limited in 2 cases, ie, knee flexion limitation of 10° with a bending angle of 0-125°, knee extension was limited in 1 case, and mild limitation of knee extension with a knee extension angle of 10 to 125° and posterior discomfort of knee joint was found in 1 case. The Lysholm knee joint function score was 45.60 ± 6.86 before the operation and 87.65 ± 2.61 at 12 months after the operation. The IKDC score was 19.27 ± 4.40 before surgery and 95.47 ± 1.87 at 12 months after surgery The difference was statistically significant (Table 2). The minimum clinical importance difference and patient acceptable symptom state of patients with knee pain were 16.7 (12 months) and 75.9 (IKDC score), respectively. For the Lysholm score, the minimum detectable change is set to 8.9, but patient acceptable symptom state is unknown in the literature.
Our IKDC score difference was 76.2, and the Lysholm score difference was 41.17, which is greater than that of minimum clinical importance difference and minimum detectable change, so they were statistically significant.
In this study, the use of an adjustable-loop cortical button device to fix and suspend the PCL avulsion fracture under arthroscopy was safe and provided good clinical results. So far, there are few reports about avulsion fractures of PCL. Because of the increasing use of 2-wheeled motor vehicles in Asian countries, more traffic accidents causing PCL avulsion fractures are reported compared with that of Western countries.
The treatment of displaced PCL avulsion fractures usually includes open reduction and arthroscopic treatment. Early surgical intervention can prevent chronic instability of joint and secondary arthritis. The earliest surgical method is open reduction and internal fixation. Burks and Schaffer
proposed a simplified posterior medial approach in 1990. The prone position, knee flexion to 30°, and the inverted L-shaped skin incision have made it a standard operation method that is more effective than the previous one.
Although suitable for all types of bone blocks, open reduction has many disadvantages, such as the need for prone position, difficulty in anatomy, high risk of bone fragmentation caused by screw extrusion, and easy damage of popliteal nerves and blood vessels, Postoperative gastrocnemius muscle weakness is caused by traction of the medial head of gastrocnemius muscle during operation, which affects the range of joint motion and surgical wound healing and so on. Patients are always more willing to undergo minimally invasive surgery when possible, thus greatly promoting the development of arthroscopy.
The advantages of arthroscopy are that it can diagnose and fix the injury of anterior bifurcate ligament, meniscus, and soft tissue at the same time, and the rate of neurovascular injury is low. It was also confirmed in previous experiments that fixation of PCL avulsion fractures using button suspension shows biomechanical properties comparable with traditional anterograde screw fixation.
This technique is minimally invasive, with less scar formation, faster healing, and better recovering of range of motion. However, this technique creates a high demand on the orthopaedic surgeons’ professional skills and requires a long learning period. Because a 4.5-mm hollow drill can easily break small and thin bone blocks, it is not suitable for smaller fracture blocks, which makes preoperational evaluation of the size of the bone blocks particularly important. Once during an operation, the small fracture piece broke, and we changed it to use suture winding to complete the operation (Fig 7). Other studies have shown that the joint fibrosis rate of arthroscopic treatment is greater than that of open reduction.
Fig 7Once the small fracture piece was broken, we changed it to use suture winding to complete the operation.
first performed assisted arthroscopic reduction and fixation of avulsion fracture of PCL of tibia. Since then, there have been a variety of arthroscopic fixation materials. Most cases were still fixed with sutures and ENDOBUTTON/suture plate or knot through the anterior part of the tibia through the bone tunnel. These studies confirmed the feasibility of using a total internal suspension device to treat avulsion fractures at the PCL stop, providing a uniform pressure distribution for avulsed bones. However, the following defects are also obvious. Although the financial burden of patients is reduced by the high-strength sutures, which require no additional fixed materials or removal, arthroscopic sutures and tunnels make the process more difficult. Moreover, it is necessary to tie a knot on the solid part of the PCL near the fracture piece, and there is a “killer turn”
between the suture and the tibia, which may lead to fragmentation and affect the reduction of the fracture. A knot needs to be tied during suturing in front of the tibia through the tibial tunnel, which is prone to similar “wiper effect” and “bungee effect.”
Comparison of arthroscopic suture bridge technique and conventional double tunnel suture technique in the treatment of avulsion fracture of posterior cruciate ligament.
Zhongguo Xiu Fu Chong Jian Wai Ke Za Zhi.2021; 35 ([in Chinese]): 829-835
At the same time, the tension of the sutures may lead to excessive stress concentration, which can easily lead to poor fracture healing. Although ENDOBUTTON fixation does not produce a killer angle, there are also the “wiper effect” and “bungee effect” because of the problem of the top gap. ENDOBUTTON needs to reserve length during the operation, which represents a lack of controllability. If the length calculation is wrong, the steel plate cannot be flipped or the reserved length is too large, resulting in a gap between the top of the bone tunnel and the graft.
The adjustable-loop cortical button fixation device used in this study is a locking band loop steel plate, with a long button at the proximal end and a circular one at the distal end, which can adjust the contraction. It is suitable for prefabricated bone tunnel of any length, reduces the error of bone tunnel length calculation according to the loop length during the operation, overcomes the deficiency of the top gap, and the button can be close to the bottom of the bone tunnel, which will not only reduce the loss of bone mass when drilling the tunnel but also avoid the 2 aforementioned effects. It is small in size, easy to operate, simple in technology, and does not require multiple sutures and bone tunnels. The study of Ezechieli et al.
also confirmed that, compared with the suture group, the initial displacement of the fixation group was significantly lower with a greater maximum failure load and better effect than that of the suture group.
Limitations
Our research has several limitations. First, because PCL tibial avulsion is still relatively rare in English-speaking countries, many published articles are not available in English, and our number of cases is not large enough; therefore, more cases are needed to draw more reliable conclusions. Second, the comparative population in the existing research is quite different, partly because of the complexity of the injury associated with ligament, meniscus, or bone injury, and partly because the exact surgical treatment and postoperative plans are different. Third, although this technique is suitable for most fracture pieces, a 4.5-mm drill may break thin bone fragments, so it is important to evaluate the size and thickness of bone fragments before operation. If the fracture is broken during operation, suture winding can be used. Fourth, the patients in our group belong to a younger age category, and it is uncertain whether the same effect would be expected for older patients.
Conclusions
This study found that arthroscopic adjustable-loop cortical button fixation treatment for PCL avulsion fractures is simple to perform, easy to reproduce, and provides satisfactory results with less complications.
Displaced posterior cruciate ligament avulsion fractures: A retrospective comparative study between open posterior approach and arthroscopic single-tunnel suture fixation.
Arthroscopic fixation for tibial eminence fractures: A clinical retrospective study of cannulated screws versus transosseous anchor knot fixation techniques with suture anchors.
All-suture anchors versus metal suture anchors in the arthroscopic treatment of traumatic anterior shoulder instability: A comparison of mid-term outcomes.
Clinical outcomes of acute displaced posterior cruciate ligament tibial avulsion fracture: A retrospective comparative study between the arthroscopic suture and EndoButton fixation techniques.
Comparison of arthroscopic suture bridge technique and conventional double tunnel suture technique in the treatment of avulsion fracture of posterior cruciate ligament.
Zhongguo Xiu Fu Chong Jian Wai Ke Za Zhi.2021; 35 ([in Chinese]): 829-835
The authors report that they have no conflicts of interest in the authorship and publication of this article. Full ICMJE author disclosure forms are available for this article online, as supplementary material.
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