Research on the dynamic behavior of flexible drilling tools in ultrashort-radius radial horizontal wells.

A flexible drilling tool is a special drilling tool for ultrashort-radius radial horizontal wells. This tool is composed of many parts and has the characteristics of a multibody system. In this paper, a numerical method for the dynamic analysis of flexible drilling tools is proposed. The flexible drill tool is discretized into spatial beam elements, while the multilayer contact of the flexible drilling tool is represented by the multilayer dynamic gap element, and the dynamic model of the multibody system for the flexible drilling tool's multilayer contact is established, considering the interaction force between the drill bit and the rock. The nonlinear dynamic equation is solved using the Newmark method and Newton-Raphson method. An analysis of the dynamic behavior of a flexible drilling tool is conducted. The results indicate that the flexible drilling tool experiences vortex formation due to the interaction between the flexible drilling pipe and the guide pipe, leading to increased friction and wear. This situation hinders safe drilling operations with flexible drilling tools. The collision force of the flexible drilling tool near the bottom of the hole is more severe than that of the other tool types, which may lead to failure of the connection.

On the development of a new flexible drill for orthopedic surgery and the forces experienced on drilling bovine bone.

This article presents the construction of a flexible drill which is designed to cut a curved canal in the bone or remove bone materials, to improve the outcome of orthopedic surgery and to facilitate minimally invasive. This article reports the design of the flexible drill and uses it in an experimental rig to evaluate the drilling force generated when cutting bovine bone. The experiments facilitate the measurement of action forces between the mill bits when moving the tip toward or across a bone sample in various configurations caused by bending the flexible drill sheath to enable cutting of a curved path of variable radius in the bone. The reaction force represents the force trying to deflect the mill bit tip away from the bone sample surface and must be resisted in order to continue cutting without deflection or buckling of the tip during the drilling of curved pathways. The experiment shows the flexible drill can cut bones in both configurations and experienced a maximal force of 3.4N in the vertical configuration and 0.54N in lateral configuration. The experimental results show that the flexible drill designed is able to produce sufficient force at variable bending angles to perform the required tasks for bone cutting.

A novel flexible drill device enabling arthroscopic transosseous repair of Bankart lesions.

We have developed a flexible drill device that makes arthroscopic transosseous repair possible, and report preliminary results. Twelve patients with post-traumatic anterior inferior glenohumeral instability were selected. SURGICAL TECHNIQUE: the flexible drill device is inserted into the shoulder joint through the posterior portal and the guide pipe unit is placed 5mm posterior to the margin of the anterior glenoid rim. The flexible drill is driven through the glenoid with the power drill, creating a hole in the glenoid. A non-absorbable suture is passed through the hole and a sliding knot tying is performed over the capsule and labrum after completing stitches with the suture hook loaded. The same procedures are repeated in the 2, 3 and 4 o'clock positions of the glenoid. There was no recurrence of dislocation at the mean follow-up period of 52.3 months. The mean Rowe score was 89.5.

Arthroscopic Transosseous Suture Repair for Bankart Lesion with a Flexible Drill Device: An Experimental and Preliminary Clinical Report

PURPOSE: Too develop a flexible drill device that can be inserted into the shoulder joint so that arthroscopic transosseous suture repair for Bankart lesion is possible. MATERIALS AND METHODS: We created a device composed of a flexible drill unit and a guide pipe unit. The flexible drill unit was made of flexible multifilament wires (1.2 mm in diameter) that was twisted into one cord so that it can flex in any direction and a drill bit (1.2 mm in diameter) that is attached onto one end of the flexible wire. The guide pipe unit was a 150 mm long metal pipe (2.0 mm in inner diameter and 3.0 mm in outer diameter), with one end bent to 30 degrees. The flexible drill set was inserted into the shoulder joint through the posterior portal of the joint. The guide pipe component was placed onto the medial wall of the glenoid so that the pipe was placed 5 mm posterior to the margin of the anterior glenoid rim. The flexible drill was driven through the glenoid by the power drill so that holes were made in the glenoid. A non-absorbable suture was passed through the hole. Tying of a sliding knot tying was accomplished over the capsule and labrum after making a stitch through the capsule and labrum with a suture hook loaded with suture passer. The same procedures were done at the 2 and 4 O'Clock positions of the glenoid. RESULTS: Five cases with Bankart lesion received arthroscopic transosseous repair with our flexible drill device. There were no intraoperative problems. Neither redislocation nor subluxation was reported at final follow-up. CONCLUSION: Arthroscopic transosseous suture repair without suture anchors and easy tying of a sliding knot are possible with a flexible drill set.