ObjectiveTo compare the parameters of screw implantation in capitolunate arthrodesis between the 2nd and 3rd metacarpal bones and via the distal dorsal capitate bone approach based on CT images of the normal wrist, and provide reference for the selection of surgical approaches and planning of screw insertion trajectory. MethodsCT data of 50 patients who met the criteria between February 2022 and April 2022 were selected as the study objects. There were 30 males and 20 females, and the age ranged from 18 to 69 years (mean, 37 years). The normal wrist alignment was conformed in all CT images. All CT data from the unilateral wrist of the patients was imported into Mimics Medical 20.0 software to construct a three-dimensional plane model, in which a virtual 3.5 mm screw was implanted between the 2nd and 3rd metacarpal bones and via the distal dorsal capitate bone approach. The angle between screw and coronal, sagittal, and transverse planes, the total length of the screw, the length of the screw in the lunate bone and the capitate bone were measured. The ratios of the length of the screw in capitate bone to the length of the long axis of the capitate bone, the length of the screw in lunate bone to the length of the long axis of the lunate bone, and the length of screw in lunate bone to the length of the screw in capitate bone were calculated. Assuming that the result of screw implantation between the 2nd and 3rd metacarpal bones was better than that via the distal dorsal capitate bone approach, the difference in length of the screw in the lunate bone between the two approaches was calculated, and the superiority test was performed. ResultsCompared with the distal dorsal capitate bone approach, the total length of the screw increased, the length of the screw in the capitate bone decreased, and the length of the screw in the lunate bone increased, the angle between the screw and coronal plane decreased, the angles between screw and sagittal, transverse planes increased after the screw was implanted between the 2nd and 3rd metacarpal bones. And the ratio of the length of the screw in capitate bone to the length of the long axis of capitate bone decreased, the ratio of the length of the screw in lunate bone to the length of the long axis of lunate bone increased, and the ratio of the length of the screw in lunate bone to the length of the screw in capitate bone also increased. All the differences were significant (P<0.05). The difference in the length of the screw in the lunate bone between the two approaches was 1.86 mm [95%CI (1.54, 2.18) mm], which was greater than the superiority margin (1.35 mm). The superiority hypothesis was supported. ConclusionCompared with the distal dorsal capitate bone approach, the screws implanted between the the 2nd and 3rd metacarpal bones in the capitolunate arthrodesis are longer in lunate bone and more vertical to the articular surface of the capitolunate joint. Theoretically, the capitolunate joint are more firmly fixed.
ObjectiveTo observe the possibility of hyper selective neurectomy (HSN) of triceps branches combined with partial neurotomy of S2 nerve root for relieving spastic equinus foot. Methods Anatomical studies were performed on 12 adult cadaveric specimens. The S2 nerve root and its branches were exposed through the posterior approach. Located the site where S2 joined the sciatic nerve and measured the distance to the median line and the vertical distance to the posterior superior iliac spine plane, and the S2 nerve root here was confirmed to have given off branches of the pelvic splanchnic nerve, the pudendal nerve, and the posterior femoral cutaneous nerve. Between February 2023 and November 2023, 4 patients with spastic equinus foot were treated with HSN of muscle branches of soleus, gastrocnemius medial head and lateral head, and cut the branch where S2 joined the sciatic nerve. There were 3 males and 1 female, the age ranged from 5 to 46 years, with a median of 26 years. The causes included traumatic brain injury in 2 cases, cerebral hemorrhage in 1 case, and cerebral palsy in 1 case. The disease duration ranged from 15 to 84 months, with a median of 40 months. The triceps muscle tone measured by modified Ashworth scale (MAC) before operation was grade 3 in 2 cases and grade 4 in 2 cases. The muscle strength measured by Daniels-Worthingham manual muscle test (MMT) was grade 2 in 1 case, grade 3 in 1 case, and 2 cases could not be accurately measured due to grade 4 muscle tone. The Holden walking function grading was used to evaluate lower limb function and all 4 patients were grade 2. After operation, triceps muscle tone, muscle strength, and lower limb function were evaluated by the above grading. Results The distance between the location where S2 joined the sciatic nerve and median line was (5.71±0.53) cm and the vertical distance between the location and posterior superior iliac spine plane was (6.66±0.86) cm. Before joining the sciatic nerve, the S2 nerve root had given off branches of the pelvic splanchnic nerve, the pudendal nerve, and the posterior femoral cutaneous nerve. All the 4 patients successfully completed the operation, and the follow-up time was 4-13 months, with a median of 7.5 months. At last follow-up, the muscle tone of the patients decreased by 2-3 grades when compared with that before operation, and the muscle strength did not decrease when compared with that before operation. Holden walking function grading improved by 1-2 grades, and there was no postoperative hypoesthesia in the lower limbs. Conclusion HSN of triceps branches combined with partial neurotomy of S2 nerve root can relieve spastic equinus foot without damaging other sacral plexus nerves.