Cemented and Cementless Fixation: Which One Suits Whom

Cemented and cementless fixation differ in how the implant is attached to the bone. With cemented fixation the space between bone and implant is filled with bone cement, which hardens within a few minutes and gives solid attachment straight away. With cementless fixation the implant is fitted tightly into the bone, after which the bone gradually grows into its porous surface. Both principles are widely used and the choice rests on the quality of the patient’s bone.

What fixation of an implant means

Fixation is how an implant holds its position in the bone over many years. This is not a secondary technical detail: it is exactly the durability of the fixation that determines whether the implant stays stable.

An implant has two parts that touch bone: the cup set into the pelvis and the stem set into the femur. The type of fixation can be chosen separately for each of them.

The construction of an implant and the function of its parts are described on a page of their own: the hip implant and its parts.

Both methods have been in use for decades. The choice between them does not depend on fashion or novelty: it rests on the state of the particular patient’s bone.

The durability of fixation is judged at two stages. The first is early stability, meaning how solidly the implant sits immediately after the operation; the second is long-term stability, meaning how well that state is maintained over the years. The difference between the two types lies precisely in how each reaches those two stages.

This terminology has practical significance. When a patient asks “which is more solid”, the answer depends on which stage is meant: cemented fixation is more solid straight away, while cementless achieves biological attachment over time.

How cemented fixation works

With cemented fixation the space between bone and implant is filled with bone cement, which is prepared during the operation and hardens within a few minutes.

Bone cement is not glue in the ordinary sense. It fills irregularities, matches the internal shape of the bone and creates a solid, uniform support. The attachment is mechanical: the cement enters the fine cavities of the bone and hardens there.

The strengths of cemented fixation:

• Immediate stability. The attachment is solid straight after the operation and does not wait for bone ingrowth.
• Independence from bone quality. It gives reliable attachment even in weak, thinned bone.
• Flexibility of shape. Cement fills irregular shapes, which is useful where the anatomy is altered.

There are considerations too: preparing and setting the cement takes its own time during the operation, and in a possible repeat procedure removing the cement is an extra stage.

The moment when the cement sets gets separate attention. Changes take place in the body at that point which the anaesthetist watches for. That is exactly why with cemented fixation the surgeon and the anaesthetist agree on this stage in advance. For the patient this stage passes unnoticed; for the team it is planned.

A practical note: cemented fixation does not mean the implant is “weaker” or “older”. That is a common belief and it is inaccurate. The method is still used actively around the world, and in particular situations it is exactly the right choice.

How cementless fixation works

With cementless fixation the implant is fitted tightly into the bone, so that it sits mechanically solid from the start. Its surface is deliberately porous and over time the bone grows into those pores.

The process has two stages. In the first, a tight fit holds the implant in position. In the second, over weeks, the bone grows into the surface and the attachment becomes biological.

The strengths of cementless fixation:

• Biological attachment. Bone and implant become one system.
• Less foreign material. There is no layer of cement.
• An advantage in repeat procedures. In a possible revision no cement has to be removed.

The consideration is tied directly to bone quality: bone ingrowth requires bone that is dense and living enough. If the bone is weak, the attachment may not be reliable.

The second consideration concerns the early period. Until the bone grows in, only the tight fit holds the implant. So after cementless fixation the loading regime is set separately and follows the surgeon’s instructions. In most cases full loading is allowed early, though this is individual.

The internal shape of the femur deserves a separate mention. The stem has to fit tightly in the canal: if the canal is very wide or irregular in shape, achieving the necessary tightness is difficult. This is often exactly the factor that steers the choice towards cemented fixation.

How the two differ from each other

The two types of fixation differ in what holds the implant in the bone and when final attachment is reached: with cement, immediately after the operation; without, over weeks.

Feature	Cemented	Cementless
Principle of attachment	Cement fills the space	Bone grows into the surface
Stability right after surgery	Immediate	Relies on a tight fit
Final attachment	Immediately after surgery	Over weeks
Demand on bone quality	Low	High
Typical patient	Older, weaker bone	Younger, denser bone
Repeat procedure	Cement has to be removed	Usually simpler
Length of the operation	The cement needs time to set	Without that stage

The table is a guide. Both types of fixation have well-studied long-term results and neither is unconditionally better than the other. The choice is decided by the state of the bone and not by the merits of a method.

The “typical patient” in the table is not a rule and applying it directly to yourself is wrong. Age is only an indirect indicator of bone quality: there are seventy-year-old patients with dense bone and fifty-year-old patients with thinned bone. That is exactly why it is the bone that is assessed, not just the date of birth.

What decides the choice

The choice is decided by bone quality, age, anatomy and any accompanying conditions. The decision is made during preoperative planning, on the basis of an X-ray.

The main factors:

1. Bone density. Dense, living bone creates better conditions for cementless fixation. Thinned bone points to cemented fixation.
2. Age. Bone density usually falls with age, though there is no strict age threshold. The decision is dictated by the actual quality of the bone and not by the year of birth: two people of the same age can have entirely different bone.
3. The internal shape of the femur. The image shows how narrow the canal is and how well a stem will fit it.
4. Accompanying conditions. Conditions affecting bone metabolism have to be taken into account separately.
5. Previous surgery or injury. Altered anatomy often steers the choice towards cemented fixation.

An important principle: wrongly chosen fixation is a greater risk than the choice of type itself. That is exactly why there is no answer of the form “this type is always better”.

Assessing bone quality does not end with the image. The final assessment also happens during the operation: the surgeon sees and feels what the bone is really like and changes the plan if necessary. This is a common situation and I explain it to patients in advance.

Osteoporosis, meaning reduced bone density, needs separate consideration. If such a diagnosis has already been made or is suspected, it affects the choice directly and often calls for separate investigation and appropriate treatment led by another specialist.

What the hybrid version is

The hybrid version means the two parts of the implant are attached by different principles: for example the cup is placed without cement while the stem is cemented.

The logic is simple. The state of the acetabulum and of the femur can differ in the same patient. If the pelvic bone is dense while the femur is thinned, the optimal decision is taken for each part separately.

The hybrid version is not a compromise. It is a deliberate choice in its own right and it is widely used.

In practice the femoral stem is most often the part that needs cemented fixation, while the acetabular cup is placed without cement. The reason is anatomical: the pelvic bone is usually denser and creates better conditions for bone ingrowth than the inner canal of the femur does in older age.

The opposite combination also exists, though it is rarer. What matters is the principle and not the combination: for each part the fixation chosen is the one that matches that particular bone.

Does fixation change the life of the implant

The type of fixation is one of the factors affecting the service life of an implant, but not the only one and not the most important.

The service life is affected by correct implant position, the material of the bearing couple, the patient’s activity level, body weight and the state of the bone over the years. Fixation is one item on that list. The subject is set out on a page of its own: how long a hip implant lasts.

The practical conclusion is this: a correctly chosen and correctly placed implant, with either type of fixation, usually works for a long time. The main question is not “with cement or without” but “what matches my bone”.

One thing applies equally to both types: the durability of fixation over time depends on the state of the bone. If bone density falls over the years, that shows in the attachment of either type. That is exactly why review visits and looking after bone health remain relevant after the operation too.

The choice of approach is unrelated to this question: the same fixation is possible through all three approaches. The comparison of approaches covers this: anterior, lateral and posterior approach.

What to remember

• Fixation is how the implant is attached to the bone.
• Cemented fixation gives solid attachment immediately after the operation.
• With cementless fixation the bone grows into the implant over weeks.
• The choice is decided by bone quality, age and anatomy.
• The hybrid version is common and does not mean a compromise.

The type of fixation is dictated by your bone and not by the age on your passport. At a consultation we will look at the X-ray together and I will tell you which option is planned: book a consultation.