Application of 3D-printed prosthesis in revision surgery with large inflammatory pseudotumour and extensive bone defect: A case report.

BACKGROUND: Hip revision surgery is the final treatment option for the failure of artificial hip joints, but it is more difficult than the initial operation. For patients with hip joint loosening around the prosthesis combined with large inflammatory pseudotumours and large segment bone defects, hip revision is even more difficult, and clinical reports are rare. CASE SUMMARY: Male, 59 years old. The patient underwent left hip replacement 35 years ago and was now admitted to hospital due to massive masses in the left thigh, shortening of the left lower extremity, and pain and lameness of the left hip joint. X-ray, computed tomography and magnetic resonance imaging revealed prosthesis loosening, left acetabular bone defect (Parprosky IIIB type), and a bone defect of the left proximal femur (Parprosky IIIA type). Inflammatory pseudotumours were seen in the left hip and left thigh. Hip revision surgery was performed using a 3D-printed custom acetabular prosthesis was used for hip revision surgery, which was produced by Arcam Electron Beam Melting system with Electron Beam Melting technology. The operation was successful, and the patient was followed up regularly after the operation. The custom-made acetabular prosthesis was well matched, the inflammatory pseudotumour was completely removed, the postoperative hip prosthesis was stable, and the old greater trochanter fracture was well reduced and fixed. The patient was partially weight-bearing with crutches 3 mo after the operation and walked with full weight-bearing after 6 mo. The hip prosthesis was stable, and there was no recurrence of inflammatory pseudotumours at the last follow-up. The Visual Analogue Scale was 3, and the Harris hip score was 90. CONCLUSION: The use of 3D-printed personalized custom prostheses for complex hip revision surgery has satisfactory surgical results and has great clinical application value.

Regulatory effects of root pruning on leaf nutrients, photosynthesis, and growth of trees in a closed-canopy poplar plantation.

A plantation of 5-year-old poplar Populus × euramericana cv. 'Neva' was used to study the regulatory effects of root pruning on nutrients, photosynthetic characteristics, and water-use efficiency (WUE) of leaves and growth rates of diameter at breast height (DBH; 1.3 m), tree height, and volume. Six root-pruning treatments were conducted with different combinations of intensity (at a distance of six, eight or ten times DBH from the trunk) and orientation (on two or four sides of the trees). Results showed that the N, P, K, photosynthetic rate, transpiration rate, and stomatal conductance of leaves were all significantly decreased by root pruning over the initial period following root pruning (30 days), but increased in the subsequent investigations. The values of the above indexes peaked in 8-2 treatment (i.e., eight times DBH distance on two sides). The leaf WUE in 8-2 treatment, and average growth rates of DBH, tree height and volume, were the highest among all treatments within 3 years of root pruning. The results indicated that the root pruning based on the appropriate selection of intensity and orientation had significant positive effects on leaf nutrients, photosynthesis, and growth of trees in a closed-canopy poplar plantation.

Effects of root pruning on the physicochemical properties and microbial activities of poplar rhizosphere soil.

This study aimed to determine the effects of root pruning on the physicochemical characteristics and microbial activities of poplar rhizosphere soil. The root systems of 5-year-old poplar (Populus×euramericana cv. 'Neva') trees were manually pruned at 6, 8, or 10 times diameter at breast height (DBH) from the trunk (severe, moderate, and light, respectively) along both inter-row sides. Moderate root pruning significantly increased the concentrations of amino acids, organic acids, and total sugars in the root exudates and decreased the pH of rhizosphere soil. This treatment also increased the contents of available nitrogen, phosphorus, potassium, and total organic carbon as well as high-, medium-, and low-activity organic carbon in rhizosphere soil. Moreover, moderate pruning increased the contents of microbial biomass carbon and nitrogen, and enhanced basal respiration, in addition to decreasing the metabolic quotients in rhizosphere soil by 8.9%, 5.0%, and 11.4% compared with control, light, and severe root pruning treatments, respectively. Moderate pruning increased the growth rates of DBH, tree height, and volume to the highest levels. Furthermore, these indices were not significantly different between the light root pruning and control groups, but varied significantly between severe and moderate root-pruning treatments. Thus, root pruning, depending on the distance from the trunk, significantly influences the physicochemical properties and microbial activities in poplar rhizosphere soil.