Abstract
Objective To investigate the surgical method and clinical efficacy of arthroscopic application of Rigidfix and Intrafix system to fix autologous 4-shaft N cord tendon (4SHG) to reconstruct anterior cruciate ligament (ACL) of knee.
Methods ① All medical records of ACL reconstruction performed under arthroscopy in Ningxia People’s Hospital between June 2009 and June 2014 were screened, and 25 cases meeting the requirements were selected. (ii) All patients underwent ACL reconstruction under arthroscopy, and the fixation method was selected to apply Rigidfix system on the femoral side and Intrafix system on the tibial side for fixation; the graft was selected from the autologous 4 femoral N cord tendon. Postoperative follow-up observation and outpatient follow-up examination period was 3-58 months. Patients were asked about their complaints, and physical examination was performed, including knee mobility, anterior drawer test and Lachman test, and the efficacy was evaluated with reference to the Lysholm knee score (see Table 1) and the International Knee Documentation Committee (IKDC) (see Table 2) knee joint score criteria. Huang Yonglu, Department of Orthopedics, People’s Hospital of Ningxia Hui Autonomous Region
After 3-58 months of postoperative follow-up and outpatient review, all patients had good postoperative results without serious postoperative complications. 25 patients had normal knee mobility, 2 patients had limited flexion and extension, 3 patients had pain in the knee, and 3 patients had a creaking sound in the anterior part of the knee during knee flexion and extension; the front drawer test was negative at follow-up, and the Lachman test was negative in 25 cases. The Lachman test was negative in 25 cases and weakly positive in 2 cases; the Lysholm score improved from (34.16±4.99) preoperatively to (90.66±4.38) postoperatively, and the IKDC score improved from (29.87±6.23) preoperatively to (81.16±3.25) postoperatively; the Lysholm score and the International Knee Documentation Committee (IKDC) score were used for the preoperative evaluation. (IKDC) scores were compared preoperatively and postoperatively at 3 months (a), 6 months (b), 12 months (c), and 24 months (d), and the t-values (Lysholm score) were 3.16 (P=0.025<0.05), 14.38 (P<0.01), 28.65 (P<0.01), and 29.28 (P< 0.01), with statistically significant differences; t-values (IKDC score) were 15.85 (P<0.01), 21.20 (P<0.01), 47.32 (P<0.01), and 52.26 (P<0.01), with statistically significant differences, respectively.
Conclusion The clinical results of arthroscopic application of Rigidfix with Intrafix fixation system for fixation of autologous 4 femoral N cord tendon for ACL reconstruction were satisfactory, with the advantages of high operability, minimal trauma, firm fixation and rapid postoperative recovery.
Keywords: arthroscopy; anterior cruciate ligament; autologous 4-strand N cord tendon; Rigidfix transverse nail; Intrafix absorbable extrusion nail
Preface
With the progress and development of modern medicine, especially the application of arthroscopic technology, orthopedic surgeons have a deeper understanding of the mechanism of anterior cruciate ligament (ACL) injury, and the diagnosis and treatment techniques continue to improve. If not reconstructed surgically, it will lead to an unstable knee joint, which will result in weakened knee function, secondary knee injury (including meniscal and articular cartilage injury) and premature degeneration of the knee joint, resulting in clinical manifestations such as knee pain, weak legs, weakness in walking, running and bouncing, which affects the performance of sports and the quality of daily life. The fundamental solution to this pain lies in the reconstruction of the ACL.
Arthroscopic reconstruction of the ACL has obvious advantages in terms of accurate positioning and minimal trauma.
It is considered the standard of care for ACL injuries because of its accurate positioning, minimal trauma, and the ability to simultaneously treat other concomitant injuries in the joint cavity, as well as the rapid recovery of knee function after surgery.
In ACL reconstruction, the selection of grafts has undergone considerable development. At present, it seems that the four-strand N-cord tendon is favored for its convenience of extraction, good tendon bone healing, and no rejection, but the key aspect is the choice of fixation method to fix the graft, which is quite important for the success of surgery and postoperative reconstruction results. There are many debates and inconclusive opinions on the different fixation methods for grafts. Current methods of fixation for ACL reconstruction include: 1. indirect fixation away from the articular surface; 2. direct fixation in the bone tunnel near the articular surface; and 3. direct fixation, which involves the use of interface screws of different materials from within the joint. Each fixation method has its advantages, but also its relative shortcomings. There is still no international standard for the method of fixation of the transplanted tendon. The former tendon knot fixation method and the peg-pile fixation method have been gradually withdrawn from the stage because of poor fixation and easy loosening. SIEBOLD R et al [1] showed that the Endobutton fixation system is prone to produce SIEBOLD R et al [1] showed that the Endobutton fixation system is prone to “bungee” and “wiper” effects, which cause enlargement of the bone tunnel, leading to relaxation of the graft, leakage of joint fluid into the enlarged bone tunnel, and delayed tendon-bone healing due to synovial fluid soaking of the grafted tendon. In recent years, direct and direct-like fixation techniques have evolved considerably. The advantage is that the fixation is closer to the internal opening of the bone tunnel, thus reducing longitudinal and sagittal displacement of the graft, reducing creep of the muscle bond, and preventing tunnel enlargement. This fixation technique has been proven in practice and favored by scholars and orthopaedic surgeons. linsalata [2] et al. found in an animal model that the more distant the graft fixation point is from the anatomical origin of the ACL, the higher the rate of bone tunnel enlargement, and the closer the fixation to the anatomical origin of the ACL, the more stable it is. The invention of Rigidfix and Intrafix fixation systems has definitely solved the problem. The Rigidfix transverse nail fixation keeps the graft in full contact with the bone tunnel by suspending and squeezing the graft, providing reliable fixation strength and effectively reducing the longitudinal movement and lateral displacement between the graft and the bone tunnel, thus avoiding “The Intrafix system at the tibial end has high fixation strength and firm fixation; the protective sheath of the screws on the outside avoids the cutting of the tendon by the threads and increases the friction between it and the tendon, which makes it more firmly fixed. At the same time, the sheath of the protective nail on the outside of the screw avoids the cutting of the threads to the tendon and increases the friction force between it and the tendon, making it more firmly fixed, and at the same time, it can make uniform and close contact between the four tendons and the bone tunnel, which has a large contact area and greatly improves the tendon-bone healing rate. In recent years, the application of Rigidfix and Intrafix fixation systems in the arthroscopic application of four-strand N-cord tendon reconstruction ACL technique has provided clinicians with a new option.
In this study, we used arthroscopic direct vision to diagnose the presence or absence of ACL rupture as a criterion for screening the conditions eligible for this study, which is currently the gold standard for the diagnosis of this disease at home and abroad. In addition, the application of Lysholm knee and IKDC knee stability score as the evaluation of knee stability index is also the current international standard for evaluating knee function, which involves a wide range of fine evaluation indexes and can accurately reflect the function of the affected knee. It has become the “gold standard” for evaluating knee function in many papers at home and abroad.
In this study, among 96 patients who underwent ACL reconstruction in Ningxia People’s Hospital from June 2009 to April 2014, 25 eligible cases were selected and operated under direct arthroscopy, with Rigidfix and Intrafix system as the fixation method and autologous 4 femoral N cord tendon reconstruction ACL as the graft. The Lysholm score and IKDC score improved significantly, the knee function recovered well, and all patients returned to work. The effectiveness and reliability of the “ACL reconstruction with Rigidfix and Intrafix system” was again verified. Subjects and Methods
1 Data and methods
1.1 Equipment
Arthroscopic system (Stryker), C-arm X-ray machine (Shimadzu), ACL reconstruction device (Stryker), RIGIDfix positioning system (Johnson & Johnson), tendon trimming table (Stryker), etc.
1.2 General data
Among the 25 patients, 17 were male and 8 were female, with a male to female ratio of 1.5:1. Age ranged from 17 to 53 years old, with an average of 37.8 years old; there were 11 cases of sports injuries, 9 cases of car accidents, and 7 cases of falls, all of which were unilateral injuries, including 17 cases of the left knee and 21 cases of the right knee. Twenty-two of them were acute injuries and three were old injuries; eight patients had combined posterior lateral structures (PMC) injuries. 21 patients had combined meniscal injuries of different degrees. The preoperative anterior drawer test (ADT) and Lachman test were positive in 25 cases. All cases were diagnosed with ACL rupture by preoperative physical examination and imaging and were diagnosed arthroscopically during surgery.
1.3 Inclusion criteria
(1) All cases were first-time ACL reconstructions, and the graft was selected from the autologous N cord tendon and woven into 4 strands; the fixation method was selected from the Rigidfix system on the femoral side and the Intrafix system on the tibial side, and the ACL reconstruction was performed arthroscopically; (2) the contralateral knee joint was normal; (3) preoperative X-ray and CT examination confirmed no intra-articular fracture, severe joint degeneration and osteoporosis; (4) arthroscopic confirmation of complete ACL fracture or laxity with more than 50% loss of function; (5) all procedures were performed by the same team of surgeons.
1.4 Perioperative management
The preparation of the perioperative period includes: (1) after the managerial examination and X-ray and MRI examination of the patient with old injury confirm the ACL injury and exclude related medical diseases, and confirm that there are no contraindications to surgery, the patient will be evaluated comprehensively, and if there are secondary symptoms such as quadriceps atrophy and limitation of knee flexion and extension activities, functional knee exercises can be performed first, and if necessary, the rehabilitation physician will assist in functional knee exercises and cooperate with (2) Patients with acute knee injury should have the affected limb fixed in a straight position to reduce the inflammatory reaction in the acute phase, usually for 1 to 2 weeks, and then surgery is feasible. During this period, the patient should perform isometric contraction of the quadriceps muscle of the affected limb, dorsiflexion of the foot and leg raising exercises.
1.5 Surgical method
The surgery was performed by the same senior surgeon. The surgery was performed in the following steps.
1.5.1 Preparation stage: prepare arthroscopic instruments (Figure 1), perform routine anterior drawer test and Lachman test examination after satisfactory anesthesia, and place a blood repellent band with the upper third of the affected limb in the thigh, which can avoid intraoperative bleeding in the joint cavity and affect the surgical field and prolong the operative time. (Note: The use of a tourniquet is contraindicated in patients with varicose veins and cardiac insufficiency). Inject 40-60 ml of saline into the joint cavity using an empty 20 ml injection needle to enlarge the joint cavity and increase the surgical operating space.
1.5.2 Knee cavity exploration and management of concurrent injuries (Figure 2, 3): the arthroscope and surgical instruments were placed at the anterior medial and lateral entrances of the knee, and the anterior and posterior cruciate ligaments, medial and lateral menisci, articular cartilage surfaces, patella, and knee capsule were explored together in the usual sequence. If there is meniscal damage, meniscoplasty or suturing is performed, and knee capsule damage is repaired together to avoid intraoperative fluid leakage causing infection and other complications. If there is detachment of articular surface cartilage injury, microfractures can be treated.
1.5.3 Preparation of the intercondylar fossa: The size of the intercondylar fossa can be clarified by cleaning the fat pad and fibrous tissue on the lateral surface of the intercondylar fossa under direct arthroscopic view with the use of a rangefinder, and intercondylar fossa shaping is feasible if the intercondylar fossa is narrow, but caution should be exercised. This increases the chance of graft impingement.
1.5.4 Graft collection and preparation: A longitudinal 75px long incision was made at 25px medial to the tibial tuberosity, at the junction of the goose foot tendon, and the tendons of the semitendinosus tendon and the thin femoral tendon could be seen by freeing the tissues with a periosteal knife, and the semitendinosus tendon and the thin femoral tendon were freed in turn, with attention to cutting the tendon membrane attached to the tendon to prevent the tendon from being cut by lateral tendon traction during the tendon retrieval. The tendon was taken from the autologous semitendinosus tendon and thin femoral tendon with a tendon extractor, and the length of the tendon was generally 22 mm to 24 mm, and the graft was trimmed using the Arthrex ACL reconstruction platform, and the repaired tendon was braided into four strands with 2# Aishibang non-absorbable thread (Figure 3), and the length and diameter were measured and prepared as a four-strand tendon whose diameter was not less than 7 mm; pretensioned 15 lbs × 15 min (Figure 4).
1.5.5 Positioning and fabrication of the bone tunnel: The knee was routinely flexed at 90°, and the tibial side was placed in the anterior internal approach with an ACL locator (50° to 55°), and the inner tibial tunnel port was selected to be located behind the center point of the ACL stop (the junction of the posterior 1/3 of the ACL tibial oval stop) (Figure 5), and the lateral femoral positioning point was first punched from the tibial positioning point with a kerf needle, and fluoroscopy was routinely performed under the C-arm machine (Figure 6) After the position was satisfactory, a suitable hollow bit was selected according to the graft diameter to establish the tibial tunnel. The distance from the outer opening of the tibial tunnel to the inner opening of the femoral tunnel is measured, and the depth of the tunnel is determined by the length of the ligament to determine the depth of the femoral lateral drilling tunnel. A guide pin is driven through the tibial tunnel using a femoral locator, and the femoral locating point is 6-7 mm before the posterior edge of the outer wall of the intercondylar fossa over the apex (11 o’clock in the right knee and 1 o’clock in the left knee).
1.5.6 Implantation and fixation of the graft: In this group, single tunnel on the femoral side and single tunnel on the tibial side were used to complete the arthroscopic ACL reconstruction, and the Rigidfix system (Figure 7) on the femoral side and the Intrafix (Figure 8) system on the tibial side were used for fixation. After establishing the “tibio-femoral” tunnel, the intramedullary part of the sighting device was inserted 30 mm to 40 mm into the femoral tunnel through the tibial tunnel, and the extramedullary part of the sighting device was placed on the lateral side of the knee joint, and the direction of the sighting device was rotated and adjusted so that the direction of the crossed nail fixation passed through the axis of the medial and lateral femoral condyles. The crossed nail bone tunnel is established through the sight using a drill bit into the 2 sockets. Remove the sight, insert the arthroscope from the tibial tunnel into the femoral tunnel, insert the 2 sockets separately with a kerfing needle, and observe whether the crossed nail bone tunnel crosses the femoral tunnel centrally (Figure 9), if it does not cross centrally, the crossed tunnel needs to be established again. The graft is introduced into the “tibiofemoral” tunnel using a perforated guide pin (Figure 10), and under arthroscopic surveillance, the sutured portion of the femoral end of the graft is completely inserted into the femoral tunnel, and the graft is left on the outside of the tibial tunnel, and the two Rigidfix cross-over nails are driven through the lateral sockets (Figure 11). The crossbar fixation of the femoral end graft was completed, and the graft was pulled to confirm that the femoral end graft was securely fixed. The tibial end was fixed with Intrafix squeeze screws, and the tibial end graft suture was tractioned. The knee was repeatedly flexed and extended 20 times to organize the four bundles of tendons at the external tibial tunnel opening to prevent crossover in the tunnel, and after straightening the four bundles of tendons, two pairs of traction lines were separated and tied at the appropriate distance from the external tibial tunnel opening, and the Intrafix tensioner (25 N) was installed, and the drawer was positioned after 20°-30° of knee flexion, The cross reamer was driven into the reaming hole in the direction of the tibial tunnel to a depth of 30 mm, and the Intrafix system expandable non-absorbable inner sleeve was inserted under the same tension and the Intrafix squeeze screw was screwed in to a depth of 30 mm (Figure 12).
1.5.7 Postoperative management: The reconstructed ACL was observed arthroscopically, and the tension of the reconstructed ACL was probed with a hooked needle, while the knee joint was moved to observe the presence of impingement. The knee cavity was thoroughly flushed, a negative pressure drainage tube was routinely placed, the wound was sutured, the affected limb was compressively bandaged, and the affected limb was externally fixed in a straight position with a cast. Intermittent ice packs were applied for 12 hours. The quadriceps isometric contraction, dorsiflexion, toe flexion and leg raising exercises could be performed after the drainage tube was removed 24 hours after surgery.
1.6 Management of concomitant injuries
Among the 38 patients in this group, all patients with combined injuries were treated by simultaneous surgery: 27 patients with different degrees of meniscus injury, 11 patients with secondary injury to the edge of the meniscus underwent edge revision; 5 patients with more severe tears and injuries extending to the edge of the meniscus underwent subtotal resection; 8 patients with loose meniscus and large free meniscus underwent partial resection; 3 patients with 10% to 20% longitudinal tears of the lateral meniscus and partially intact medial meniscus underwent repair suture. The meniscus was repaired in 2 patients with disc meniscus found under arthroscopy, and meniscus repair was performed in 7 patients with meniscus overturned and stuck in the joint cavity, and meniscus repositioning was performed intraoperatively; 11 patients had a combination of lateral collateral ligament injury, medial structure, and posterior lateral structure injury, 8 patients with minor injury were not treated, and 3 patients with more than 3 degrees of lateral collateral ligament (MCL) injury had reinforced suture 3 patients with MCL injury of degree 3 or more were treated with reinforced suture repair.
1.7 Postoperative treatment and rehabilitation
All patients were put in a straight position with external cast after surgery, which could not only reduce the postoperative traumatic reaction, but also avoid the postoperative joint extension in some patients, and the medicine could be changed on the second day after surgery, the drainage device was removed, and the affected limb was allowed to start isometric contraction muscle training of the quadriceps, dorsiflexion and toe flexion exercises of the affected foot and leg raising exercises. One week after surgery, the external cast was removed, and the affected limb was adjusted to 30° of flexion and 0° of extension by wearing a chuck-adjustable brace, and active knee flexion and extension activities were performed without pain. After 3 weeks (Figure 15), the patient could gradually increase weight-bearing walking with the crutches and gradually increase knee flexion and extension activities and muscle strength exercises. At 6 weeks postoperatively (Figure 16), the knee flexion and extension can reach 130° of flexion and 0° of extension, and the patient can gradually walk with full weight bearing by abandoning the crutches, while strengthening the muscle stress and coordination training. The brace could be removed at rest and worn during walking exercise and night sleep. 3 months later, the brace was removed and the patient could resume office work; 6 months after surgery, cycling and jogging exercises could be performed according to the actual recovery of the patient, and normal sports could be resumed 9-12 months after surgery.
1.8 Follow up and evaluation
In this study, the general follow-up and outpatient follow-up records (including camera data) of the selected cases before surgery, 3 months, 6 months, 12 months and 24 months after surgery were recorded, including the presence of postoperative complications (including wound healing, presence of infection, joint swelling, joint cavity effusion and deep vein embolism (DVT), etc.), knee mobility and muscle strength of the affected limb. The joint stability examination included the anterior drawer test and the Lachman test. Lysholm score, International Knee Documentation Committee (IKDC) score were used to compare preoperative and postoperative scores at 3 months (a), 6 months (b), 12 months (c) and 24 months (d) two by two. Patients’ satisfaction with postoperative recovery and return to work were also recorded. The above recorded data were analyzed comprehensively to assess the surgical results.
2 Statistical methods
The collected data, i.e., Lysholm score and IKDC score results were statistically analyzed by SPSS12.0 statistical software, and the measurement data were expressed as mean ± standard deviation (), one-way ANOVA was used for multiple group comparisons, t-test was used for intergroup comparisons, X2 test was used for counting data, Pearson correlation coefficient test and multiple linear regression analysis were used for correlation analysis, and P was taken as two-sided, and statistical significance was considered at P<0.05. < span="">
Results
In all cases, the symptoms of knee instability disappeared after surgery, and the wound healed in one stage without serious complications such as infection and deep vein embolism. 5 patients with postoperative joint swelling and fluid in the joint cavity were given joint cavity aspiration, and the fluid was completely absorbed in 3 cases, while 2 cases had fluid again and joint pain. In one case, 3 months after surgery, the joint was still stiff, with 90° of flexion and 10° of extension, and regular functional knee exercises had no significant effect. In one case, the knee joint was stiff after surgery, with 70° of flexion and 30° of extension. After 3 months of discharge, the knee joint was still stiff. The third time, the knee was given under anesthesia, and then fixed in a plaster cast for 2 weeks, and the cast was removed after 2 weeks. Two cases had knee pain associated with cold stimulation and good knee function without special treatment. All patients returned to work, and all of them had a negative anterior drawer test at follow-up; 36 cases had a negative Lachman test and 2 cases had a weak positive test (see Table 1). The Lysholm score and IKDC score improved at 3 months postoperatively compared with the preoperative scores, and significantly improved at the 6-month postoperative review. The difference was significant (P<0.05) by t-test for the scoring data (see Table 2). < span="">
Table 1 Examination evaluation index
Joint stability
Front drawer test Larchman test
Positive (number of cases) Negative (number of cases) Positive (number of cases) Negative (number of cases)
Preoperative 38 0 38 0
3 months postoperatively 0 38 0 (2 cases of weak positivity) 36
6 months postoperatively 0 38 0 38
12 months postoperatively 0 38 0 38
24 months postoperatively 0 38 0 38
Note: Satisfactory results were obtained in preoperative and postoperative knee stability checks
Table 2 Two-way comparison of Lysholm score and IKDC score of the affected knee before surgery and at the follow-up (n=38)
Method Preoperative
Postoperative
a b c d
Lysholm 34.16±4.99 43.29±3.20 65.19±4.59~ 84.82±4.29~ 91.06±4.38~
t -3.16 -14.38 -28.65 -29.28
P 0.025 0.000 0.000 0.000
IKDC 29.87±6.23 59.28±5.26 69.36±4.33~ 79.11±4.39~ 81.16±3.25~
t -15.85 -21.20 -47.32 -52.36
P 0.000 0.000 0.000 0.000 0.000
Note: ~P<0.05, compared with corresponding preoperative scores < span="">
DISCUSSION
Based on the development of arthroscopic techniques, firm and reliable fixation of the grafted tendon in ACL reconstructive surgery is the weak point of the procedure and has a decisive influence on the outcome [7]. In this group of patient records, the Rigidfix and Intrafix systems were applied arthroscopically to fix the autologous four-strand N cord tendon for ACL reconstruction, and careful preparations were made before, during, and after surgery, with appropriate graft selection and excellent fixation, and the surgical results were satisfactory.
4.1 Perioperative preparation.
In this group of cases, interventions were performed in the perioperative period, which is quite important for the smooth operation, postoperative rehabilitation and the speed of recovery. 2 patients had postoperative knee stiffness and poor functional recovery, which were associated with the patients’ knee injury mechanism and the lack of adequate knee functional exercises before surgery. The reason for this was that both patients were injured in a car accident and had compound injuries to the affected knee. Preoperative functional knee exercises were not performed regularly due to pain, and postoperative exercises were more difficult, which may have contributed to the patients’ poor postoperative recovery.
In this group of patients with acute knee injuries, the affected limb was fixed in a straight position with external cast braking, usually for 1 to 2 weeks, and surgery was feasible, and after surgery, the affected limb was also fixed in a straight position with external cast braking, so as to reduce the inflammatory reaction of the knee in the acute phase and reduce the chance of postoperative infection. In addition, observations have shown that patients who do not do extension fixation of the affected knee often have difficulty in fully straightening the knee after surgery and have 5° to 3° of flexion, and the results are not obvious when the knee is given compression extension exercises. Patients with old knee injuries, most of whom have quadriceps atrophy, are given adequate preoperative functional exercises for the affected knee to allow the muscles around the knee to increase in strength, which lays the foundation for a more stable postoperative knee.
4.2 Intraoperative points of attention.
Three patients in this study case underwent posterior lateral structure strengthening repair sutures. The purpose of selecting the repair is that posterior lateral structure injury will cause axial instability of the knee joint and the patient’s lower leg will rotate outward. If the ACL reconstruction alone is performed without posterior lateral structure repair, the lower leg will rotate outward during movement, causing the reconstructed ligament to be repeatedly stretched outward, which will eventually cause the reconstructed ligament to fail.
When establishing the main femoral tunnel and the 2 lateral cross-nailed bone tunnels, it is necessary to repeatedly determine whether the 2 cross-nailed tunnels are centered and crossed with the femoral tunnel. In 3 cases in this group, after removing the cross-nails and entering the femoral medulla with the arthroscope, one cross-nailed tunnel was deviated from the femoral tunnel when entering the cross-nailed tunnel with the kerfing needle for observation, so the scope was adjusted again to ensure the correct position and then the cross-nailed tunnel was established again. The crossed tunnel was re-adjusted to ensure the correct position and the two tunnels were confirmed to be centered and crossed vertically. Analysis of the reasons for the intraoperative non-centered passage of the two tunnels showed that the patients in question were young patients with hard bone, and that the nail head slipped when the crossed nail was struck, deviating from its original position. Without careful confirmation, the Intrafix cross-over nail may not pass through the center of the graft when struck into the tunnel or may not pass through the graft at all, resulting in fixation failure or postoperative knee motion with a broken nail and the graft coming out of the bone tunnel, causing irreparable damage.
4.3 Graft selection.
The selection of the graft is quite important in ACL reconstruction; it must have sufficient tensile strength to overcome displacement of the graft under cyclic loading and facilitate healing of the muscle bond and bone tract. In North America and elsewhere, the use of bone-patellar tendon (middle 1/3)-bone (BPTB) graft is quite popular, as it has sufficient strength, easy fixation, short tendon-bone healing time, and secure fixation as a reconstructive graft, and used to be the international gold standard for ACL reconstruction[8] . Although a large number of studies have reported that there is not much difference in clinical outcomes between BPTB and N cord tendon after ACL reconstruction[9-11] , it was found that patients with ACL reconstruction using BPTB suffer from numerous postoperative complications, such as susceptibility to patellofemoral arthritis, patellar fracture, subpatellar fat pad fibrosis, patellar tendon contracture, kneeling prepatellar pain, and affecting patellofemoral development in adolescents[12- 13]. Therefore, the use of BPTB in ACL reconstruction has been somewhat limited. Since Billottid first completed the arthroscopic application of a single semitendinosus tendon to reconstruct the ACL in 1989, the technique of using the N cord tendon as graft material in ACL reconstruction has come a long way [14]. At present, the arthroscopic application of autologous N cord tendon for ACL reconstruction has become the consensus of the majority of scholars. In our study, the case selection of four strands of autologous N cord tendon has more advantages: (1) convenient to take, easy to accept by patients; (2) its tensile strength is 2.5-3 times that of normal ACL, fully meeting the mechanical requirements of ACl replacement; (3) few postoperative complications, significantly reducing patellofemoral joint popping, almost no kneeling knee pain, quite low occurrence of traumatic arthritis, and almost no effect on patellar development (4) no rejection of the autograft and fast tendon bone healing after implantation of bone tract fixation. Therefore, the subjective IKDC score at the postoperative follow-up was relatively high. In addition, we chose braided muscle-bond grafts with a diameter greater than 7 mm in order to ensure tight extrusion fixation of the Intrafix transverse nail; the spacing of braided muscle-bond sutures was kept at 25 px and not too dense, because braided threads are non-absorbable and too dense braiding is not conducive to tendon bone contact and healing.
4.4 Retention of the residual end or not.
There is still more controversy as to whether to preserve the residual ACl. It has been found that intraoperative preservation of the remaining portion of the ACL facilitates early blood flow to the reconstructed graft and the establishment and ingrowth of nerve tissue, and the ligament stump preserves the nerve tissue and mechanoreceptors in it, facilitating postoperative proprioceptive recovery [15-17]. The preservation of the remaining bundle of the cruciate ligament in ACL reconstruction is now accepted by most orthopaedic surgeons. In all cases of this study, the ACL stump was preserved intraoperatively as much as possible, and the stump was placed over the reconstructed graft at the end of the reconstruction, which was one of the important reasons for the significant improvement in both IKDC and Lysholm scores of knee function and satisfactory recovery of joint function in this group.
4.5 Choice of graft fixation.
The selection of the graft fixation method in ACL reconstruction has been a rather difficult problem. scholars and orthopaedic surgeons at home and abroad, through a large number of animal models and clinical application studies, have found that the Rigidfix and Intrafix systems have excellent fixation and satisfactory clinical results compared to other fixation methods. kousa et al [18] applied a special device to fix the animal model and used six types of internal Blagojević Z [19] et al. used the Rigidfix system to reconstruct the anterior cruciate ligament in a clinical setting, and after long-term postoperative follow-up, all patients had good postoperative results. This technique was considered worthy of promotion. Wang Xianquan et al [20] applied the Rigidfix and Intrafix systems to fix the N cord tendon to reconstruct the ACL under arthroscopy, and compared the patient’s knee mobility, clinical symptoms, physical examination, MRI examination and Lysholm score preoperatively and postoperatively, suggesting significant clinical efficacy and significant improvement in symptoms. Zhang Shaozhan [21] et al. concluded that the Rigidfix system and Intrafix system have the advantages of reducing the “wiper effect”, achieving a 360-degree bond between the graft and the bone with strong and reliable fixation, promoting tendon-bone healing, and avoiding cutting the tendon. The advantages of Rigidfix
In this study, the Rigidfix and Intrafix systems were used to fix the autologous four-strand N-cord tendon, and intraoperative measurements and postoperative MRI revealed that the Rigidfix and Intrafix fixation methods were closer to the joint surface and closer to the anatomical stop of the normal ACL. At follow-up, the function of the affected knee was evaluated in terms of the patient’s subjective sensation, return to motion, and physician’s physical evaluation, respectively, using knee stability tests including anterior drawer test and Lachman test, and knee stability scores including Lysholm score and IKDC knee function score for evaluation. The results of the study found that the mobility of the affected knee increased at 3 months after surgery, clinical symptoms improved, and Lysholm and IKDC knee function scores improved compared with the preoperative period, and the indexes improved significantly at 6 months or more after surgery ( P < 0.05). The reliability of Rigidfix and Intrafix fixation modalities was fully demonstrated, and it is a technique worth promoting.
4.6 Postoperative rehabilitation
Exercise therapy with appropriate physical and psychological therapy is commonly used after arthroscopic surgery [22]. The aim is to restore the patient’s knee function better and faster, to resume work and participation in sports as early as possible, and to improve the quality of life. All patients in this group had a postoperative rehabilitation treatment plan and used a combination of postoperative continuation treatment measures guided by the surgeon and rehabilitation physiotherapy by the rehabilitation physician. We believe that the external fixation of the affected limb in extension for 1 week after ACL reconstruction is beneficial to reduce the traumatic reaction and avoid the situation that some patients cannot fully straighten the knee joint and have difficulty in straightening it after surgery. After one week, the flexion-adjusting brace was changed and individualized progressive muscle strength and joint loading training was performed, which significantly promoted the recovery of joint function and enhanced the efficacy of surgery.
Conclusion
The combined use of the Rigidfix and Intrafix systems for fixation of the graft tendon during ACL reconstruction surgery is a new tendon fixation technique that has only been introduced in recent years. In this study, 38 patients were fixed with autologous N cord tendon grafts using Rigidfix and Intrafix systems in ACL reconstruction, and satisfactory clinical results were achieved with follow-up observations, and all of them returned to work and greatly improved their quality of life. This result is the result of many factors, but the Rigidfix and Intrafix systems are the key to the success of the surgery, which has the advantages of simple operation, less trauma, reliable graft fixation, and fast postoperative recovery.