However, in the previous surgical treatment, due to the irregular shape of the navicular bone itself and the inadequate intraoperative exposure, the requirement for its anatomical repositioning was not very high, and more consideration was given to the promotion of its healing. With the in-depth study of the mechanism of navicular fracture and long-term follow-up analysis of postoperative patients, it was found that some patients with navicular fracture (especially delayed healing and non-healing of navicular fracture) have the so-called “proximal carpal dorsal instability” (dorsal intercalated segment instability) due to the obvious displacement of the fracture end, the presence of bone defect or the combination of navicular ligament injury. If DISI is not corrected in a timely manner, the non-physiological redistribution of stresses in the wrist joint may lead to late formation of “carpal collapse secondary to scapholunate advanced collapse” (DISI). scapholunate advanced collapse (SLAC) or scaphoid non-union advanced collapse (SNAC), resulting in pain and severe impairment of wrist function. This leads to wrist pain and severely impairs the function of the affected wrist. In fact, after recognizing the nature of DISI, it can be corrected during surgery for navicular fractures and the deformity correction can be maintained by using appropriate wedge-shaped bone grafting, which is not only simple but also can achieve good results. MATERIALS AND METHODS 1. GENERAL DATA: A total of 26 patients with navicular fractures with DISI treated at the Department of Hand Surgery, Nagoya University Hospital from 1996 to 2000 were selected with complete medical history, examination, treatment and follow-up data. The patients were 24 males and 2 females, aged 16 ~ 51 years (29.0 ± 10.9 years), with the affected wrist being right-sided in 16 cases and left-sided in 10 cases. The shortest period from injury to surgical treatment was 2 weeks and the longest period was 10 years (mean 14.1 ± 26.0 months), with a postoperative follow-up period of 4 ~ 30 months (10.2 ± 6.4 months). Cause of injury: 8 of the 26 patients were injured by fall, 5 by sports injury, 4 by fall, 4 by traffic accident, 1 by work accident, and 4 by traumatic injury. The diagnosis of DISI was confirmed by the measurement of the radial lunar (bone) angle in the contrast lateral radiograph of the affected wrist and the healthy wrist, and the former was considered DISI if it was greater than 10° of the latter. In addition, these patients also underwent preoperative wrist arthroscopy to confirm the presence of concomitant navicular ligament injury under microscopy. 4. Preoperative treatment: All patients had been fixed in a tubular cast for 2 weeks to 3 months. Four patients requested surgery more than 2 years after the injury because they felt that the disease was seriously affecting their life and work. 5.Surgical method: brachial plexus anesthesia, conventional inflatable tourniquet. The wrist arthroscopy was performed first, then a “Z” incision was made with the navicular tuberosity as the center, the radial carpal flexor was separated to the carpal capsule on the ulnar side, the capsule and the radial carpal ligament were cut longitudinally to fully expose the navicular fracture and its distal and proximal ends, the embedded soft tissue at the fracture end was excised, and the fracture was thoroughly debrided to normal bone with a scraper. Under intraoperative fluoroscopy, the lunate bone is inserted from the dorsal side with a 2.0 mm Kirschner pin and pried distally to correct DISI. At this time, the two broken ends of the navicular fracture are propped as far as possible, the size of the bone defect is measured, and accordingly the bone is taken from the distal end of the ilium or radius, trimmed into a wedge shape, and its tip is inserted from the anterolateral to the posterior medial side, first fixed with a 1.5 mm diameter Kirschner pin along the long axis of the navicular bone as an aid, and the fracture is confirmed under fluoroscopy After the fracture is satisfactorily repositioned, the navicular bone is fixed with the Herbert nail. The fluoroscopy again confirmed that the Herbert’s nail was well positioned and that the head and tail of the nail were not exposed to the bone surface, and that the fracture was securely fixed during the passive ulnar and radial deviations of the affected wrist. Remove the Creutzfeldt pin that pries the lunate bone and, if appropriate, the Creutzfeldt pin that aids in fixation of the navicular bone (this pin may be retained until 4-6 weeks postoperatively if it is felt that the Herbert nail is not very stable in fixing the implanted cuneiform bone mass). The radial carpal ligament and joint capsule are repaired and the incision is closed. External fixation in a tubular cast under the elbow is performed. In patients with combined navicular ligament injury, the navicular and lunar bones should be fixed with a Kirschner pin for 4 ~ 6 weeks after intraoperative prying and repositioning of the lunar bone, and navicular ligament repair can be performed if possible. For patients with proximal navicular fracture, if the navicular is fixed with Herbert’s nail, both palmar and dorsal incisions should be made, with the palmar incision used for debridement and bone grafting and the dorsal incision for implantation of Herbert’s nail (due to the smaller fracture fragment at the proximal end in proximal fracture, it is more stable to implant Herbert’s nail from the proximal end). 6. Postoperative treatment: The patient was fixed in a cast for 4 weeks after surgery, and the stitches were removed together with the cast removal. After removal of the cast, active functional exercises were performed under the guidance of the attending physician, but weight-bearing on the affected wrist was avoided until the fracture healed clinically, and regular follow-up was performed. All patients had stage I wound healing. The shortest healing time was 3 months and the longest was 1.5 years, with a mean healing time of 6.1±3.4 months. Pain: The results of the last follow-up visit of each patient showed that only three patients had mild or moderate pain under heavy weight-bearing of the wrist joint, while the rest did not report any pain in the affected wrist. Joint mobility: In four patients, the active range of motion (ROM) of the affected wrist was completely normalized at the final follow-up. The overall postoperative wrist range of motion was 105.4°±32.0° (104.7°±24.6° preoperatively, p=0.36 by paired t-test (same statistical method), not significant) and the ulnar radial range of motion was 59.6°±23.4° (50.1°±16.1° preoperatively, p=0.98, not significant) in all patients. ). Grip strength: Because of the large variation in grip strength values with each measurement, the grip strength statistics were expressed as a percentage of the measured value on the affected side to the healthy side. Imaging examinations: frontal, lateral and navicular position plain films showed good healing of the navicular fracture, and no loosening, displacement or fracture of the Herbert nail was observed. The difference between the preoperative healthy and affected navicular lunar angles was found to be 22.2°±9.1°, and the postoperative difference between the two was 2°±8.38° by paired t-test, with p<0.001, a highly significant difference. The mean corrected angle through surgery was 20.2°±11.1°. However, residual DISI (14 - 20°) remained in three patients after surgery, and further analysis showed that the presence of residual DISI was not associated with postoperative outcomes (pain, grip strength, and joint range of motion). The concept of DISI was first proposed by Linscheid and Dobyns in 1972, and there is a clear anatomical and dynamic basis for the development of the deformity of the wrist joint. On the other hand, in the normal neutral position, the longitudinal stress lines through the cephalic and radial bones are not in a straight line, the stress line of the cephalic bone is on the dorsal side and the stress line of the radial bone is on the palmar side, both of them act on the lunar bone to form a dorsal extension force couple; in addition, the normal angle of the distal radial joint to the palmar side is 10~15°, the combined effect of the three makes the lunar bone physiologically inclined to dorsal extension, but due to the strong navicular ligament connecting the lunar bone and the navicular bone with palmar flexion tendency, the navicular and lunar bones are always in A dynamic balance state. Once the navicular ligament is injured or the navicular bone is fractured and displaced, a palmar flexion deformity of the navicular bone (or distal fracture of the navicular bone) combined with a dorsiflexion deformity of the lunar bone, known as DISI, may occur, resulting not only in instability of the entire wrist joint and abnormal stress distribution, but also in a change in the correspondence between the radial and mid-wrist articular surfaces, leading to bony disorders such as SLAC or SNAC. arthropathy such as SLAC or SNAC. It is because of such serious consequences that we should pay great attention to it and correct it in time. For DISI measurement, American scholars mostly use the navicular (bone) lunar (bone) angle, while Japanese scholars tend to use the radial lunar angle [5], and there is little difference between these two measurement methods in assessing DISI due to navicular ligament insufficiency injury, but in the case of navicular fracture with distal metacarpal angulation, the former measurement actually contains part of the distal navicular angulation, and there is a tendency to make the DISI angle larger Therefore, the radial lunar angle measurement method was used in this study. It is usually considered that in patients with navicular ligament injury, surgical correction is necessary only when the DISI exceeds 20° or is greater than 10° and there are obvious clinical symptoms, but in such patients with unstable navicular fractures, there is a tendency to relax the limit of correction during surgery, and some are set at 15° or 10°. Considering that it is not only a simple method to correct the navicular fracture while treating it surgically, but also to obtain better results, our group chose 10° as the surgical standard. The wedge-shaped bone graft was used to treat the navicular fracture with DISI because it was considered that DISI in this case is mostly caused by the distal end of the navicular fracture being palmarly flexed while the proximal end is dorsally extended with the lunar bone, thus forming compression and bone defects on the radial and palmar sides of the fracture line. Theoretically, injury to the navicular ligament is an important cause of DISI, but only one of the cases in this group was clearly seen to have a tear of the navicular ligament under the arthroscope, and it was easy to find that this case had only 2 weeks from injury to surgery, so the ligament injury was clearly visible. In other cases, the duration of the disease was several months or years, and even if there was an injury to the navicular ligament, it was easily concealed by local reactive synovial hyperplasia or fibrous scar formation and was difficult to detect. Therefore, for those DISI that cannot be corrected intraoperatively despite adequate wedge bone grafting, the possibility of navicular ligament injury should be considered, and the navicular and lunar bones should be fixed intraoperatively while resetting the lunar bones with kerf pins. Although the residual DISI did not affect the recent clinical outcome (which is consistent with recent foreign reports), its long-term consequences need to be further observed. Overall, due to the presence of the navicular fracture, the mutual mobility of the carpal bones was relatively large, so the preoperative limitation of the range of motion of the wrist joint was not very severe in many patients (especially in chronic cases), regardless of wrist pain, which made the difference in the range of motion of the joint before and after surgery not statistically significant. However, the more important significance of this surgery is that it restores the anatomical relationship and dynamic balance of the bones of the wrist joint, relieves the pain of the wrist joint, enhances the grip strength of the wrist joint, and ensures the usability of the affected wrist in life and work and long-term, stable results.