This aim of this study was to assess the feasibility of designing and introducing generic 3D-printed instrumentation for routine use in total knee arthroplasty. Instruments were designed to take advantage of 3D-printing technology, particularly ensuring that all parts were pre-assembled, to theoretically reduce the time and skill required during surgery. Concerning functionality, ranges of resection angle and distance were restricted within a safe zone, while accommodating either mechanical or anatomical alignment goals. To identify the most suitable biocompatible materials, typical instrument shapes and mating parts, such as dovetails and screws, were designed and produced.Aims
Materials and Methods
In major orthopaedic departments, typically several total knee systems are used. Each system requires several sets of instruments, each set with many trays of complicated and expensive parts. The logistics and costs of maintainance are considerable. Our overall goal is to investigate the feasibility of autoclavable single-use 3D printed instruments made from a polymeric material, used for any type of total knee design. The procedure will be standardized and adjustments easy to implement. Each set will be packaged individually, and used for a single case. There are many aspects to this study; in this part, the aims are to identify suitable materials for autoclavability and strength, and then to compare the accuracy of a novel design of 3D printed tibial cutting guide with a current metallic guide. Test samples were designed to simulate shapes in current instruments, such as mating pegs and holes, threaded screws, and slotted blocks. Each set was produced in biocompatible materials, ABS-M30i, VeroClear (MED610), Ultem1010, and Nylon 12. Each part was laser scanned, and then imaged virtually using a reverse engineering software (GeoMagic). Manual measurements of key dimensions were also made using calipers. The parts were autoclaved using a standardized protocol, 30 minutes at 250° F. All parts were re-scanned and measured to determine any changes in dimensions. To test for strength and abrasion resistance, the slotted blocks were pinned to sawbones model tibias, and an oscillating saw used to cut through the slot. A compact 3D printed tibial cutting guide was then designed which fitted to the proximal tibia and allowed varus-valgus, tibial slope and height adjustments. A small laser attached to the guide projected to a target at the ankle. Tests were made on 20 sawbones, and compared with 20 with a standard metal cutting guide. Digitization was used to measure the angles of the cuts.Introduction
Methods
The authors call attention to the fact that puncture wounds of the foot are often considered simple, but can have potentially serious complications and sequelae. In the majority of the cases, osteomyelitis in children is a haematogenous infection and the microorganism involved is a gram-positive coccus. The role of the puncture wound in osteomyelitis has been overlooked in the past. We present our experience with six cases of osteomyelitis following deep puncture wounds of the foot. We reviewed six cases (1990–1999) of pseudomonas osteomyelitis in children. At the time of the injuries, five cases were boys younger than the age of seven and one was 12 years old. The sites affected were: metatarsal (2), phalanx (2) and calcaneous (2). The cause of injury was tree splinter (2), fork (1), needle (2) and nail (1). At the time of injury, all of the wounds contained foreign matter that was not initially completely removed and osteomyelitis developed as a result. The time interval until definitive diagnosis ranged from 5 to 730 days. There is a similar history in all of the cases. For two or three days following the injury, the symptoms showed improvement and the injured site became swollen, tender, and painful afterwards. Treatment in all cases was hospitalisation, debridement and parenteral antibiotics for 18 to 22 days. After hospitalisation, an oral antibiotic (ciprofloxacin) was taken in two cases for three months and in four cases for four months. After treatment, mean follow-up was 60 months (range 8 to 98 months). We have had no sequelae, recurrences or early growth arrest, and we consider the results to be good in all of the cases. Puncture wounds of the foot should not be considered as “simple” injuries. Proper initial treatment is critical for the prevention of subsequent and potentially serious complications.
