Objective To introduce two minimally invasive surgical methods for the treatment of tibial intercondylar crest avulsion fractures. Methods From March 2003 to August 2007, 19 procedures were performed. The tibial guide of the ACL was used to accurately determine the location of the borehole in the bone bed or bone block, and a No. 5 AHP suture was inserted across the base of the ACL and led through the borehole and bone tunnel in the bone bed or bone block for extra-articular knotting and fixation in 11 cases; a 1.5-mm Clinique needle was inserted from the patella still against the 1/3 to fix the fracture block, and the skin and joint capsule were incised for 5 mm, and a 4-cm hollow nail was screwed along the Clinique needle to fix the fracture block in 8 cases. The fracture block was fixed by screwing in a 4-cm hollow nail in 8 cases. Results All cases were followed up for 4-18 months with an average of 11.6 months; 18 cases had normal knee mobility and one case had 00-0-1050 extension and flexion mobility; radiographs showed that all fractures healed and all but one were anatomically repositioned. Conclusion Arthroscopic surveillance surgery for tibial intercondylar crest avulsion fractures can minimize surgical trauma, and the surgical method is simple and easy, especially hollow screw fixation, which is an effective treatment for these fractures. In recent years, the incidence of anterior crucial ligament (ACL) avulsion fractures (i.e. tibial intercondylar crest avulsion fractures) has increased significantly with the increase in traffic accidents and sports participation. Since the traditional treatment method is incision and repositioning, wire, wire or screw internal fixation, which is very traumatic, we use the minimally invasive method of arthroscopic surgery to treat these injuries and have achieved good results. From March 2003 to August 2007, a total of 19 patients with tibial intercondylar crest avulsion fractures underwent arthroscopic surgery. There were 15 male cases and 4 female cases; age 15-38 years, mean 24.3 years. According to the Meyers-MCKeever [1] tibial intercondylar crest fracture typing method, there were 2 cases of type II and 17 cases of type III; 18 cases with acute trauma, 3-17 days after injury to surgery, mean 7.6 days, and 1 case with old injury, 7 months after injury. There were 3 cases of combined meniscal injury, 2 of which were bony avulsion of the anterior horn of the lateral meniscus and 1 case of oblique tear of the posterior horn of the medial meniscus; 1 case of combined II degree injury of the medial collateral ligament; there was no limitation of movement of the affected knee before the injury, and no obvious arthritic manifestation was seen on the preoperative X-ray. 1.2. The knee arthroscope was used to insert the planer and arthroscope through the anterior inferior internal (AM) and anterior external (AL) entrances to fully remove the blood and clots accumulated in the joint. First, a routine examination of the knee joint was performed, paying special attention to the presence of avulsion of the anterior horn of the meniscus on both sides, and the free bone fragments were removed. The bone bed and the avulsed bone are carefully cleaned, and the bone is adequately cleaned for old injuries, and the fibrous scar, i.e., the bone scab, is scraped away to create a fresh bone wound. The goal of the repositioning is to restore the ACL alignment and normal tension, and to flatten the bone as much as possible by sledging it back into place. The medial anterior meniscus angle and the anterior transverse knee ligament embedded between the fracture ends should also be removed with a probe through the AM portal. Following this method of revision, microscopy showed that anatomic or subanatomic reduction was obtained in all 18 patients. The fixation with the Achebon wire was performed as follows: a small 1.5-cm longitudinal incision was made medially to the tibial tuberosity, and the anterior cruciate ligament tibial guide was used to precisely position the fracture at an angle of 45 degrees, and two bone tunnels were prepared with a 2-mm diameter Clinique needle. If the avulsed bone is large, the intra-articular exit of the bone tunnel can be positioned in the anterior middle third of the bone, or in the anterior edge of the bone bed if the bone is small or comminuted; the fine wire tabs are introduced into the two bone tunnels and exposed intra-articularly under the guidance of the trocar needle, and the fine wire tabs are lapped with the No. 5 Apex wire that passes through the anterior cruciate ligament proximal to the avulsed fracture, and the fine wire is pulled so that the No. 5 Apex wire is led out of the two bone tunnels to A small longitudinal incision is made medially next to the tibial tuberosity. After confirming that the repositioning is satisfactory, the Apex wire is tied tightly outside the joint in the bent knee 300 position. After satisfactory repositioning of the larger avulsion fracture, a 5-mm long incision is made with a sharp knife at the medial edge of the middle 1/3 of the patella to reach the articular cavity and point to the tibial stop of the ACL. A long guide pin of 1.5 mm in diameter is drilled into the center of the avulsed fracture at an angle of 45-50° to the tibial plateau, approximately 40-45 mm posteriorly and inferiorly. 38-42 mm AO self-tapping cancellous bone hollow screws are selected and screwed in with a hollow screwdriver along the guide pin. Postoperatively, a cast or brace was applied for 4-6 weeks. In two cases with bony tears of the anterior meniscus, suture fixation was performed arthroscopically at the same time as the anterior tibial intercondylar spine fracture. In the other case, an arthroscopic meniscoplasty was performed in combination with an oblique tear of the posterior horn of the meniscus. 1.3, Results All 19 patients were followed up for 4-18 months, with a mean of 11.6 months; 18 cases had normal knee mobility and 1 case had limited mobility, with a mobility of 00-0-1050. radiographs showed that all fractures healed and no obvious signs of traumatic arthritis were seen. Except for one old fracture, all fractures were anatomically repositioned. Postoperatively, all stability tests of the knee joint were normal. 2. Discussion The tibial intercondylar crest avulsion fracture is a type of anterior cruciate ligament injury, which can restore the stable function of the anterior cruciate ligament if it receives timely and appropriate treatment early. On the contrary, it may cause knee instability or deformed healing, resulting in intercondylar fossa impingement and causing limited knee extension, which can only be remedied by surgical methods such as ACL reconstruction or intercondylar fossa plication and bone block removal in the late stage, so type II-III fractures are absolute indications for surgery [1-3]. In the early stage of fracture, the fracture block is easily repositioned after removal of traumatic scabs; whereas in old fractures, the anatomical repositioning of the fracture block is difficult due to contracture of the anterior cruciate ligament and scarring of the tibial fracture wound base, so the timing of surgery is best within two weeks after the injury. In one case of unsatisfactory repositioning in our group, the fracture block was still mildly supinated because it was an old fracture and the shortened anterior cruciate ligament could not be fully released during surgery. The traditional surgical approach is to use a long curved incision through the parapatellar area for repositioning and fixation, which requires the patella to be dislocated laterally to expose the fracture site, with involvement of the suprapatellar capsule and parapatellar support band. Because of the high surgical trauma, long hospital stay, heavy postoperative reaction, difficult recovery of knee function, and postoperative knee stiffness are common [4].Mclenn[5] was the first to use arthroscopic techniques to treat intercondylar crest fractures of the tibia with fixation using a kyphotic pin. Arthroscopic surgery can significantly reduce the interference with joint function and can achieve the same effect of incisional repositioning and internal fixation, which is a minimally invasive surgical technique that has developed rapidly in recent years. After arthroscopic surgery, the patient’s reaction is significantly reduced, and most patients do not need pain medication and only need to be discharged from the hospital 3-4 days after the surgery with 2-3 days of sedation of common antibiotics. The postoperative functional recovery and fracture healing were satisfactory. The method of fixation of the fracture block with No. 5 Achebon wire is technically demanding and requires the surgeon to be skilled in surgery. First the anterior cruciate ligament tibial locator is used so that the intra-articular exit of the bone tunnel can be precisely located. If the bone block is large, it is positioned in the anterior middle third of the bone block, with the bone hole preferably passing through the fracture block; in the case of a small bone block or comminuted fracture, it is positioned at the anterior edge of the bone bed. Posterior placement of the outlet should be avoided to prevent upturning of the bone block and improper repositioning. Next, the use of an epidural needle to pass the AICL suture across the base of the ACL and to lead the suture out of the bone tunnel is the key to the surgical step. We use a 2 mm diameter hollow thin tube with a built-in wire loop of good elasticity, the wire loop can automatically open after pushing out the hollow tube, insert the hollow thin tube into the joint via the bone tunnel, push the wire loop into the joint, introduce the suture into the wire loop, and draw the wire to lead the suture out of the joint, which cleverly solves this technical problem, is simple, fast and easy to perform. As the strength of No.5 Aishibang wire can be compared with 0.4mm wire, the fixation strength is good, and the stimulation of the knee joint by wire fixation and the second stage of wire removal surgery are avoided. Meanwhile, for avulsion fractures with fragmented fracture blocks, a guiding wire can be used to weave a stitch of AICL suture in the injured part of the anterior cruciate ligament and lead out the joint for fixation afterwards, which can achieve a better fixation effect. Fixation of tibial intercondylar crest avulsion fractures with AO titanium hollow screws is a relatively simple and quick surgical method, which was first started in clinical use by Lubowitz et al [6], with minimal trauma and reliable fixation. However, the fracture block is required to be intact and the diameter is required to be greater than 5 mm, because the minimum diameter of AO hollow nail is 3 mm. If the fracture block is large, we prefer to use a hollow nail of 4 mm diameter, and when the fracture block is small, it is better to add a spacer. The key to the success of the operation is the angle of the guide pin implantation and the position of the guide pin in the center of the fracture block after the fracture has been repositioned, the guide pin is at an angle of 45-50° to the tibial plateau, and is drilled about 40-45 mm in the posterior and inferior direction, and after checking the position of the fracture block, the hollow screw of about 40 mm in length is screwed in with the guide pin, and the fracture block is fixed firmly. The operation takes about 30 minutes. The initial strength of the tibial intercondylar crest avulsion fracture fixed with AICB sutures and hollow nails does not meet the requirements for early functional exercise of the knee joint, and postoperative braking is still required, and in a few cases, postoperative limitation of knee joint movement may occur. To prevent knee adhesions, we used a brace to brake the affected knee and instructed the patient to maximize passive movement of the patella (up, down, left, and right directions) to prevent adhesions of the knee extension device, and to practice quadriceps function to prevent significant muscle atrophy. In this way, 4-6 weeks after removal of the brace, the mobility of the patella can be close to normal and the mobility of the knee can be easily restored, which is an easy and effective rehabilitation method.