A Robotic grinding station based on an industrial manipulator and vision system.

Due to ever increasing precision and automation demands in robotic grinding, the automatic and robust robotic grinding workstation has become a research hot-spot. This work proposes a grinding workstation constituting of machine vision and an industrial manipulator to solve the difficulty of positioning rough metal cast objects and automatic grinding. Faced with the complex characteristics of industrial environment, such as weak contrast, light nonuniformity and scarcity, a coarse-to-fine two-step localization strategy was used for obtaining the object position. The deep neural network and template matching method were employed for determining the object position precisely in the presence of ambient light. Subsequently, edge extraction and contour fitting techniques were used to measure the position of the contour of the object and to locate the main burr on its surface after eliminating the influence of burr. The grid method was employed for detecting the main burrs, and the offline grinding trajectory of the industrial manipulator was planned with the guidance of the coordinate transformation method. The system greatly improves the automaticity through the entire process of loading, grinding and unloading. It can determine the object position and target the robotic grinding trajectory by the shape of the burr on the surface of an object. The measurements indicate that this system can work stably and efficiently, and the experimental results demonstrate the high accuracy and high efficiency of the proposed method. Meanwhile, it could well overcome the influence of the materials of grinding work pieces, scratch and rust.

A new internal fixation technique for acetabular fractures involving the quadrilateral plate.

BACKGROUND: The treatment of acetabular fracture involving the quadrilateral plate is a technical challenge, and the optimal management of the fracture remains controversial. We have designed a new implant (named acetabular fracture reduction internal fixator, AFRIF) for acetabular fractures involving the quadrilateral plate. This use of this new device was not investigated therefore we conducted a retrospective study aiming to determine whether the AFRIF can achieve satisfactory clinical and radiological outcomes for quadrilateral plate fracture. HYPOTHESIS: The AFRIF for quadrilateral plate fracture is an acceptable option to treat acetabular fracture involving the quadrilateral plate. MATERIALS AND METHODS: We performed a retrospective analysis of prospectively collected data on 24 patients (15 males and 9 females) with acute displaced quadrilateral plate fractures of the acetabulum who were treated by the AFRIF between August 2011 and May 2015. The mean age of the patients was 61.5±9.2 years (range, 31-82 years). All hips had protrusion of the femoral head, of these 5 hips with associated articular impaction of the medial roof. The type of fractures included anterior column in 4, anterior column+posterior hemitransverse in 3, associated both column in 11, T-shaped in 6 patients. The approaches included Limited Ilioinguinal (5 patients) and Limited Standard-Ilioinguinal combined with Kocher-Langenbeck (19 patients). Quality of reduction was evaluated and graded as anatomical (0mm to 1mm of displacement), imperfect (2mm to 3mm displacement) or poor (more than 3mm displacement) according to the residual displacement as defined by Matta. The final follow-up clinical outcome was classified as excellent (18 points), good (15-17 points), fair (13-14 points) or poor (<13 points) in terms to the modified Merle d'Aubigné-Postel score, and radiological outcomes evaluation were as excellent, good, fair, or poor based on Matta score. RESULTS: The mean duration of follow-up was 45.7±13.0 months (range, 24-60 months). Average operative time and bleeding amount was 110.3±30.8min (range, 105-210min) and 950.6±348.6ml (range, 300-1500ml), respectively. There was anatomical reduction in 17 patients (17/24, 70.8%), imperfect in 5 patients (5/24, 20.8%), and poor in 2 patients (2/24, 8.3%). All of the quadrilateral plate fractures achieved anatomical except one imperfect reduction. No re-protrusion of the femoral head was observed at the final follow-up. The mean modified Merle d'Aubigné-Postel score was 16.9±2.0 points (range, 10-18 points), and 83.3% (20 of 24) have good or excellent radiological outcomes. DISCUSSION: The findings suggest that the AFRIF for quadrilateral plate fractures may prevent protrusion of the femoral head and achieve good to excellent clinical and radiological outcomes. LEVEL OF EVIDENCE: IV, retrospective study.

Bi-functional titanium-polydopamine-zinc coatings for infection inhibition and enhanced osseointegration.

The ideal orthopedic implant coating is expected to both inhibit microbial infection and promote osseointegration. In this study, Zn ions were immobilized on a Ti substrate via a polydopamine (PDA) chemical surface modification to prepare Ti-PDA-Zn coatings. Scanning electron microscopy (SEM), atomic force microscopy (AFM), energy-dispersive X-ray spectroscope (EDS), X-ray photoelectron spectroscopy (XPS), contact analysis system, and inductively coupled plasma atomic emission spectrometry (ICP-AES) were used to analyze the morphology, composition, wettability, and zinc ions release of the coatings. The Ti-PDA-Zn coatings demonstrated excellent antibacterial activities in vitro against both Staphylococcus aureus and Escherichia coli. The coatings additionally displayed good biocompatibility, as confirmed by cytoskeletal observations and cell viability assays. Furthermore, the in vivo results confirmed the excellent antibacterial properties and improved osseointegration capability of the Ti-PDA-Zn coating in the presence of S. aureus. The present findings indicate that the Ti-PDA-Zn coatings prepared herein have potential application in orthopedic implantation.

[CLINICAL OBSERVATION OF ROTATING-PLATFORM PROSTHESIS FOR VALGUS KNEE DEFORMITY].

OBJECTIVE: To investigate the effectiveness of rotating-platform prosthesis for valgus knee deformity in total knee arthroplasty (TKA). METHODS: A retrospective analysis was made on the clinical date of 25 cases (28 knees) of valgus deformity undergoing primary TKA by using Gemini MK II rotating-platform prosthesis. There were 6 males (7 knees) and 19 females (21 knees), aged from 47 to 82 years, with an average age of 64.8 years. The unilateral knee was involved in 22 cases and the bilateral knees in 3 cases. The causes included osteoarthritis in 20 cases (22 knees), rheumatoid arthritis in 4 cases (5 knees), and traumatic arthritis in 1 case (1 knee). The disease duration was 2-22 years (mean, 10.4 years). The main clinical symptoms were arthralgia combined with limited movement. According to the Keblish grade, there were 13 knees of mild deformity, 11 knees of moderate deformity, and 4 knees of severe deformity. RESULTS: All incisions healed by first intension. No complications of infection, cutaneous necrosis, deep venous thrombosis, and pulmonary embolism occurred. The postoperative follow-up duration was 12-60 months (mean, 25.4 months). Medial instability and palsies of nervus peroneus communis occurred in 1 and 2 cases respectively, and all were cured after symptomatic treatment. No patellar and polysthylene insert dislocation, prosthetic loosening or infection was observed. The Hospital for Special Surgery (HSS) score, femoral tibial angle, maximun flexion and extension angles, knee range of motion, and patellar score were significantly improved at last follow-up when compared with preoperative ones (P<0.01). CONCLUSIONS: The rotating-platform prosthesis for valgus deformity can obtain satisfactory effectiveness, but it requires precise soft tissue balancing technology, and the long-term effectiveness remains further observation.

[MID- AND LONG-TERM EFFECTIVENESS OF THIRD-GENERATION CERAMIC-ON-CERAMIC TOTAL HIP ARTHROPLASTY IN YOUNGER PATIENTS].

OBJECTIVE: To analyze the mid- and long-term effectiveness of the 3rd-generation ceramic-on-ceramic (CoC) total hip arthroplasty (THA) in the younger patients. METHODS: A retrospective analysis was made on the clinical data of 68 younger patients (73 hips) who accepted the 3rd-generation CoC THA between March 2001 and May 2009. Of 68 cases, 39 was male and 29 was female with the average age of 38.6 years (range, 18-50 years); there were 15 cases (15 hips) of osteonecrosis of the femoral head, 9 cases (9 hips) congenital dysplasia of the hip, 5 cases (8 hips) of ankylosing spondylitis, 10 cases (10 hips) of osteoarthritis of the hip joint, 12 cases (12 hips) of traumatic hip arthritis, 12 cases (12 hips) of femoral neck fracture, 4 cases (6 hips) of rheumatoid hip arthritis, and 1 case (1 hip) of tumor of the femoral neck. The Harris score and University of California Los Angeles (UCLA) score were used to evaluate the hip joint function and activity level respectively. The visual analogue scale (VAS) was used to assess postoperative thigh pain. Radiological signs of osteolysis, loosening, and alumina ceramic related complications were evaluated continuously. And the Kaplan-Meier survival analysis was used to assess the prosthesis survival. RESULTS: The average duration of follow-up was 9.7 years (range, 6-14 years). Sandwich ceramic liners fracture was observed in 3 cases (3 hips), and revision was performed; 1 case had "squeaking" hip because of physical activity. At last follow-up, Harris score and UCLA score were significantly improved when compared with preoperative scores (P<0.05). Bony healing was obtained in all patients, without osteolysis, loosening, and thigh pain. The VAS score was 0. The 5-year and 10-year cumulative survival rates for ceramic fracture revision were 98.6% and 95.9%, and the 5-year and 10-year cumulative survival rates for osteolysis and loosening revision both were 100%. CONCLUSION: The 3rd-generation CoC prosthesis offer an excellent option for younger patients in THA and the mid- and long-term effectiveness are satisfactory.