science

Hip resurfacing

Hip resurfacing is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Hip resurfacing rather than just read about it. In short: Hip resurfacing is a surgical alternative to total hip replacement (THR). The procedure consists of placing a cap (usually made of cobalt-chrome metal), which is hollow and shaped similarly to the cap of a mushroom, over the head of the femur while a matching metal cup (similar to what is used with a THR) is placed in the acetabulum (pelvis socket), replacing the articulating surfaces of the person's hip joint and r…

Key takeaways

Hip resurfacing belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Hip resurfacing to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Hip resurfacing from memory before moving on to harder problems.

Reference excerpt

Hip resurfacing is a surgical alternative to total hip replacement (THR). The procedure consists of placing a cap (usually made of cobalt-chrome metal), which is hollow and shaped similarly to the cap of a mushroom, over the head of the femur while a matching metal cup (similar to what is used with a THR) is placed in the acetabulum (pelvis socket), replacing the articulating surfaces of the person's hip joint and removing very little bone compared to a THR. When the person moves the hip, the movement of the joint induces synovial fluid to flow between the hard metal bearing surfaces lubricating them when the components are placed in the correct position. The surgeon's level of experience with hip resurfacing is most important; therefore, the selection of the right surgeon is crucial for a successful outcome. Health-related quality of life measures are markedly improved and the person's satisfaction is favorable after hip resurfacing arthroplasty.

Uses A person's suitability for hip resurfacing is decided by the person's anatomy and the surgeon. Hip resurfacing is generally more suitable for younger people who are not morbidly obese, are clinically qualified for a hip replacement (determined by the doctor), have been diagnosed with noninflammatory degenerative joint disease, do not have an infection, and are not allergic to the metals used in the implant. The potential advantages of hip resurfacing compared to THR include less bone removal (bone preservation), a reduced chance of hip dislocation due to a relatively larger femoral head size (given that the person has an anatomically correct femoral head size), and easier revision surgery for any subsequent revision to a THR device because a surgeon will have more original bone stock available. Hip resurfacing has the potential of being a solution for life, allows a normal ROM (range of movement) and minimizes the amount of "stress shielding", compared with THR. Since the femoral neck is retained and the femoral cavity with its marrow not opened up two other advantages exist, namely no risk of blood clots by fatty marrow that can enter the blood stream with the THR procedure and no risk of introducing bacteria in the opened femoral canal resulting in a deep infection as can happen with the THR procedure. The potential disadvantages of hip resurfacing are femoral neck fractures (rate of 0–4%), aseptic loosening, and metal wear. Due to the retention of the person's complete femoral neck other advantages exist: Surgeon induced discrepancies in leg length (as could happen with THR) are now minimized. Also, the toe-in or toe-out faults that could occur interoperatively with THR are now over because the femoral neck that determines foot direction is left undisturbed with hip resurfacing. On February 10, 2011, the U.S. FDA issued a patient advisory on metal-metal hip implants, stating it was continuing to gather and review all available information about metal-on-metal hip systems. On June 27–28, 2012, an advisory panel met to decide whether to impose new standards. No new standards, such as routine checking of blood metal ion levels, were set, but guidance was updated. According to the Australian Orthopaedic Associate National Joint Replacement Registry (AOANJRR) 2018 Annual Report, hip (total) resurfacing is overwhelmingly used for males (98% of total resurfacing hip replacement were males), and has declined in popularity since the mid-2000s (the number of total resurfacing procedures in 2017 was 78.7% less than 2005). In 2006, the United States FDA approved hip resurfacing using the Birmingham Hip Resurfacing (BHR) system, designed by British Orthopaedic surgeon Derek McMinn. All other FDA approved devices have been removed from the US Market. The BHR is no longer suggested for use in women. There are several other manufacturers of hip resurfacing systems, mainly in Europe.

Contra-indications Hip resurfacing should not be used on people who have severe bone loss in their femoral head, those with large femoral neck cysts present (typically found at surgery) or cysts that are close to the head neck junction, or people who have poor bone stock or osteoporosis. Caution should be used for people who have rheumatoid arthritis, are tall, thin, or small boned, those with osteonecrosis (poor blood supply) to the femoral head, or those with femoral head cysts > 1 cm on an x-ray taken before surgery. Metal-on-metal resurfacing systems are generally unsuitable for women of child-bearing age due to unknown effects of metal ion release on the fetus. There are hip resurfacing components that have a ceramic coating on metal femoral head component and cross linked polyethylene plastic as a liner for the socket or cup area making it not metal on metal. The plastic sleeve can be replaced if needed without removing the main components.

… excerpt ends here. Continue reading the full article.

Illustrations

Worked examples

Example 1 — a first encounter with Hip resurfacing

Start with the simplest possible case. Write down what Hip resurfacing claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Hip resurfacing before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Hip resurfacing ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Hip resurfacing

In research: Hip resurfacing appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Hip resurfacing in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Hip resurfacing is common in secondary-school and first-year university syllabi. It links to neighbouring topics Orthopedic implants, Orthopedic surgical procedures, Pelvis, so understanding it makes those chapters shorter.
In everyday life: Look for Hip resurfacing outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Hip resurfacing in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Hip resurfacing means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Hip resurfacing out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Hip resurfacing in simple terms?

Why does Hip resurfacing matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Hip resurfacing?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Hip resurfacing.