المدينة الطبية · مختبر الأجهزة · الجهاز 29 من 69
الغرسات العظمية
Orthopedic Implants
الغرسات العظمية في مختبر الأجهزة في المدينة الطبية من BMEssentia. افتحه بتقنية ثلاثية الأبعاد تفاعلية، وفكّكه قطعةً قطعة، وتعرّف إلى طريقة عمله، ثم تعلّمه على منصة BMEssentia واسأل إسنشيا عنه.
محتوى مختبر الأجهزة في هذه الصفحة باللغة الإنجليزية، كما هو داخل المدينة الطبية.
- عدد الأجزاء: 10
- عدد التكوينات في مختبر الأجهزة: 6
- يُعرف أيضًا باسم: Hip Implant, Knee Implant, Orthopaedic Implant, Joint Replacement
مختبر الأجهزة
Orthopedic Implants
5 mm thick with nine combination holes, screwed to the outside of a bone. The screws thread into the plate as well as into the bone, so the angle between them is fixed and the construct does not rely on friction between plate and periosteum. It is the highest-volume implant in orthopaedics and the one whose mechanics are most often misread.
التكوينات
نسخ الجهاز في مختبر الأجهزة.
Locking plate and screws, diaphyseal bridging construct
5 mm thick with nine combination holes, screwed to the outside of a bone. The screws thread into the plate as well as into the bone, so the angle between them is fixed and the construct does not rely on friction between plate and periosteum. It is the highest-volume implant in orthopaedics and the one whose mechanics are most often misread.
Intramedullary nail, statically locked
7 mm holes. It sits where the bone's own neutral axis is, which is the single fact that makes it a different machine from the plate.
Total hip: cemented femoral stem, press-fit acetabular shell
0 mm polyethylene liner. Two interfaces on one construct, deliberately: one that transfers load continuously from the moment it is mixed, and one that transfers nothing but friction until bone grows into it.
Total knee: femoral component, tibial tray and polyethylene insert
0 mm. The highest-volume joint replacement there is, and the only implant in this tray that does not fail by breaking.
كيف يعمل
استكشفه في مختبر الأجهزة.
Two springs, one moment, and which axis
Set the bench to each configuration in turn and read one number: the share. 96 on the hip stem and 100 on the pedicle construct, and it is undefined on the knee because nothing lies alongside it.
A cube, a fourth power and a first power
Three sensitivities on one bench and they are not interchangeable.
Ten million cycles, and an exponent of minus twenty-seven
Start the frame and watch the counter. A million cycles a year means ten years is ten million, which is precisely where an endurance limit is quoted, so the service life of an implant is the x-axis of the standard curve and not a coincidence worth ignoring.
A cone, an unrecorded force and a coefficient nobody measured
Select the hip configuration and work the taper controls, because the pair of numbers they produce is the least intuitive thing on this device.
A joint that does not break
Select the knee and look for a share. There is not one, and that absence is the lesson: the tray sits on a cut surface in compression, nothing lies alongside it in bending, and no moment is divided.
الأجزاء
قطعةً قطعة.
Size range rack and the increment between sizes
A stepped rack holding the same implant seven times over, ascending from the smallest to the largest, each one sealed in its own barrier with the size printed where a gloved hand can read it at arm’s length. It is the least interesting-looking object on the bench and it decides more about the mechanics than anything else on it.
Trial components and templating overlays
A blue tray of anodised parts that look like the implant and are not it, five of them in ascending size, with a transparent graduated acetate lying over the top. The anodised colour exists so that a trial can never be mistaken for the thing that stays in.
Double sterile barrier packaging and lot record
Two barriers, not one: an inner blister tray with a peelable lid and an outer pouch round it, with a label carrying the size, the lot and a sterilisation indicator that has changed colour. It is packaging in the sense that a pressure vessel is a container.
Instrument case and implant tray
A grey case with its lid hinged back, a silicone bracket mat inside with ribbed slots, and a label on the base. Everything for one construct lives in it and is accounted for out of it, and the ribs are the reason nothing inside it rattles.
Insertion driver and torque-limiting handle
A steel shaft with a hexalobular tip at one end, a rubber handle at the other, and a graduated clutch between them that slips at a set torque. It is the only instrument in the room that puts a number on a force, and the number it puts on decides how hard a screw is allowed to grip.
Passivated oxide surface and its finish specification
Three coupons of the same alloy on a small stand, identical in composition and different in finish, from a mirror through a satin to a matte. On top of all three is an oxide film a few nanometres thick that cannot be seen at all, and under all three is the reason one of them would last and another would not.
Cut-section board and load-path schematic
A dark board on an easel with the cross-sections drawn on it and, on a plinth in front, the same sections built as objects at six times life size, with the bone they sit beside drawn at the same enlargement and the neutral axis marked as a thin orange line through the middle of it.
Alloy and polymer coupon board
Six coupons on a small dark board, each labelled with its modulus: titanium alloy, cobalt-chromium, stainless steel, polyethylene, bone cement and a polymer stiff enough to be structural. Beside them, implied rather than mounted, is bone at seventeen gigapascals, and that is the number all six are being compared against.
Cyclic test frame and cycle counter
A two-column frame with an actuator, a load cell and a coupon held between four rollers in a bending fixture, and a counter beside it reading a number with seven digits in it. It is the only object in the room where a few million cycles is a physical thing happening rather than a figure in a table.
Retrieval inspection station and wear-scar record
A steel bench with a stereo microscope over a stage, a ring light round the objective, a bagged component that has come back out lying under it, a calliper and a roughness stylus beside it, and a screen carrying the record. This is where an implant is finally judged, and almost everything that matters here is a surface rather than a shape.
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