Spinal needle force monitoring during lumbar puncture using fiber Bragg grating force device.

A technique for real-time dynamic monitoring of force experienced by a spinal needle during lumbar puncture using a fiber Bragg grating (FBG) sensor is presented. The proposed FBG force device (FBGFD) evaluates the compressive force on the spinal needle during lumbar puncture, particularly avoiding the bending effect on the needle. The working principle of the FBGFD is based on transduction of force experienced by the spinal needle into strain variations monitored by the FBG sensor. FBGFD facilitates external mounting of a spinal needle for its smooth insertion during lumbar puncture without any intervention. The developed FBGFD assists study and analysis of the force required for the spinal needle to penetrate various tissue layers from skin to the epidural space; this force is indicative of the varied resistance offered by different tissue layers for the spinal needle traversal. Calibration of FBGFD is performed on a micro-universal testing machine for 0 to 20 N range with an obtained resolution of 0.021 N. The experimental trials using spinal needles mounted on FBGFD are carried out on a human cadaver specimen with punctures made in the lumbar region from different directions. Distinct forces are recorded when the needle encounters skin, muscle tissue, and a bone in its traversing path. Real-time spinal needle force monitoring using FBGFD may reduce potentially serious complications during the lumbar puncture, such as overpuncturing of tissue regions, by impeding the spinal needle insertion at epidural space.

Surgical technique and outcome of uncemented THR using HA coated stems in fused and deformed hips due to ankylosing spondylitis.

BACKGROUND: Uncemented Total Hip Replacement (THR) is at present an accepted treatment in patients with severe deformity of the hip caused by advanced ankylosing spondylitis. MATERIALS AND METHODS: We studied 20 patients, 2 female and 18 male, who had 29 THRs, all through a posterior approach. The patient's age at index surgery ranged from 20 to 47 years (mean 35.1). No trochanteric osteotomy was performed in any patient. A double cut of the femoral neck was performed for hips which were ankylosed in external rotation and flexion. Follow-up ranged from 18 to 46 months (mean 22.2 months). RESULTS: The mean preoperative Harris Hip Score (HHS) was 34.6. At last follow-up all hips were considered excellent, with a mean HHS of 90. Radiographs revealed that the acetabular and femoral components were satisfactorily positioned with no radiographic evidence of loosening. No heterotrophic ossification was found. CONCLUSIONS: 1) Trochanteric Osteotomy was not found necessary to expose the hip through the posterior approach. 2) Uncemented THR using HA coated stem in the treatment of severe deformity of the hip caused by advanced ankylosing spondylitis allowed good lower limb function.