Medical Oncologist
CION Cancer Clinics
Growing prostheses for children after a bone tumour | CION Cancer Clinics
A growing prosthesis is a metal implant that replaces the bone removed with a tumour and can be lengthened in small steps as your child grows, so the operated leg keeps pace with the other. It is used for tumours near the knee in children with years of growth ahead. This page explains the two kinds, what lengthening involves, and what the pathway asks of a family. CION Cancer Clinics’ surgical oncologists in Hyderabad can talk this through with you.
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Medically reviewed by Dr. Muralidhar MuddusettyConsultant Surgical Oncologist · MBBS (AIIMS), MS (Surgery, AIIMS), DNB (Surgical Oncology), MRCS (Edinburgh) · last reviewed September 2026, next review due September 2027
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On this page
- What is a growing prosthesis, and when is it used for a child?
- The two kinds of growing implant
- What a non-invasive lengthening session involves
- Words you will hear, in plain language
- A growing implant and rotationplasty, compared
- Four things parents tell us, and what is actually true
- What this page cannot tell you
- Common questions about growing prostheses for children
The short answer
What is a growing prosthesis, and when is it used for a child?
A growing prosthesis is a metal implant that replaces the bone removed with a tumour and can be lengthened in small steps as your child grows, so the operated leg keeps pace with the other. It is used when a bone tumour sits near the knee in a child who still has years of growth ahead, and when the leg can be saved with a clear margin, a rim of healthy tissue around the tumour.
Why an ordinary implant is not enough in a child
Bones grow from plates near their ends, and the plates around the knee do most of the growing in the leg. Removing a tumour there removes the growth plate with it. A fixed-length implant would leave the leg shorter each year.
What it asks of the family
Regular lengthening sessions through childhood, close follow-up, physiotherapy after each step, and almost certainly further surgery at the end of growth to exchange the implant for an adult one. It is a long commitment.
Who it does not suit
Very young children with a great deal of growth left, because the implant would need too many steps and operations. Children whose tumour has grown into the main nerve or vessels. And families who cannot reach the centre regularly, because an implant not lengthened on time fails in its purpose.
For some children, rotationplasty or amputation with a modern prosthesis gives a more dependable result. Ask your team to compare them honestly.How it is lengthened
The two kinds of growing implant
The difference is whether lengthening needs a small operation or can be done from outside the body.
Minimally invasive
Lengthening is done through a small cut under a short anaesthetic, turning a screw inside the implant. Each session means a day in hospital and a wound to heal.
What that means
- An anaesthetic at each step
- A small infection risk each time
Non-invasive
The implant carries a small motor driven by a magnetic field. The leg is placed inside a coil in the clinic and the implant lengthens by a few millimetres with no cut and no anaesthetic.
What that means
- An outpatient visit, not an admission
- The implant costs more
What both share
Stems fixed into the remaining bone, a hinged knee, the same infection and loosening risks as any tumour implant, and a further operation at the end of growth to fit an adult implant.
Not every centre uses growing implants. Ask which kind yours uses, and how many children it has treated.Not sure whether this applies to you?
Ask an oncologistIn the clinic
What a non-invasive lengthening session involves
Measuring the difference
The lengths of both legs are checked, on the couch and on X-ray. The aim is to keep the operated leg within a small margin of the other, not to overtake it.
The coil
Your child lies with the leg inside a ring-shaped coil. The implant lengthens by a few millimetres over a few minutes. Most children feel a stretching sensation rather than pain.
Walking out
There is no wound and no anaesthetic, so your child walks out the same day. The leg may ache for a day or two as the muscles adjust to the new length.
Stretching afterwards
Physiotherapy in the days after each step keeps the knee bending fully. Muscles that are not stretched after lengthening tighten, and a stiff knee is the commonest avoidable problem.
Booking the next one
Sessions are spaced through the year according to how fast your child is growing. Missing them lets the legs drift apart, so the dates matter.
In the consultation
Words you will hear, in plain language
- Growth plate
- The soft band near the end of a child's bone where new bone is made. Tumours near the knee usually take the growth plate with them.
- Leg length discrepancy
- The difference in length between the two legs. Lengthening is timed to keep this small, because a large difference strains the hip and spine.
- Extendible or expandable
- Other names for a growing implant. They all mean the same thing.
- Skeletal maturity
- The point at which the bones stop growing, in the mid to late teens. Lengthening stops here, and the adult conversion is usually planned.
- Adult conversion
- The operation at the end of growth that exchanges the growing implant for a standard adult one, which is stronger and simpler.
- Revision
- Any further operation on the implant, for infection, loosening or wear. Over a lifetime, a child with an implant should expect more than one.
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Side by side
A growing implant and rotationplasty, compared
Growing implant
Rotationplasty
The leg looks like the child's own, with a long scar
The foot faces backwards and works as a knee inside a prosthesis
Many lengthening steps and usually further operations
Usually one operation; the limb grows on its own
Running, jumping and contact sport are limited
Running, cycling and sport are usually possible
Infection or loosening can mean losing the implant
Fewer mechanical problems over a lifetime
Appearance is easier for many families to accept
Appearance takes getting used to, for the child and for others
Commonly believed
Four things parents tell us, and what is actually true
"Once the growing implant is in, she will never need another operation."
Almost every child with a growing implant has further surgery: the adult conversion at the end of growth, and often a revision for infection, loosening or wear along the way. It is a pathway of operations, not a single one.
"The implant grows by itself, like bone."
It does not. Every step of lengthening is done by the team, in clinic or in theatre, on a schedule set by how fast your child is growing. If the sessions are missed, the legs drift apart and the difference is hard to make up.
"It is better to wait until he has finished growing before any surgery."
The tumour does not wait. Surgery is timed by the cancer treatment, usually after the first cycles of chemotherapy, and delaying it risks the margin and the limb. The growing implant exists so that surgery need not wait for growth.
"Children with an implant cannot go to school or play with others."
Most children return to school within weeks of the operation and join in most of what their friends do. Contact sport and jumping are the usual limits. The physiotherapist and the school can plan around them together.
Being straight with you
What this page cannot tell you
It cannot tell you whether a growing implant is the right operation for your child. That depends on the MRI, the tumour type, how it answered chemotherapy, how much growth is left and how far you live from the centre. Rotationplasty or amputation may serve some children better, and a good team will say so.
It cannot tell you how the leg will function
That depends on which muscles could be kept, on how well the knee is stretched after each lengthening, and on how the implant holds up over the years. Ask about the likely limits before you decide.
What to ask the team
- Which kind of growing implant, and how many children have you treated with it?
- How many lengthening sessions, and how often will we need to travel?
- What operations should we expect before adulthood?
- How would rotationplasty or amputation compare for our child?
- What does the scheme or insurance cover, including the implant?
Questions we are asked
Common questions about growing prostheses for children
At what age can a child have a growing implant?
There is no fixed age. It depends on how much growth is left, how large the bone is, and whether the implant can be anchored safely. For the youngest children, the bone is often too small and the remaining growth too large, and the team will discuss rotationplasty or amputation instead.
Does lengthening hurt my child?
With a non-invasive implant most children describe a stretching or pulling feeling for a few minutes, and an ache for a day or two afterwards. With the minimally invasive type there is a small wound each time. Stretching exercises after each step make the next one easier.
How many operations will my child have in total?
The first operation to fit the implant, the adult conversion at the end of growth, and very possibly a revision or two for infection, loosening or wear along the way. Ask your surgeon for their own experience with the implant they are proposing.
Can my child play sport with a growing implant?
Swimming, cycling and walking are usually encouraged. Running, jumping and contact sport put shock through the hinge and are generally advised against. This is one of the honest differences from rotationplasty, and it is worth weighing if your child is sporty.
Will the operated leg end up the same length as the other?
That is the aim, and with regular lengthening it is usually close. A small difference is common and is managed with a shoe raise. A large difference usually means sessions were missed or the implant reached its limit, which is why the schedule matters.
What happens when she stops growing?
The growing implant is usually exchanged for a standard adult implant, which is stronger and simpler. That operation is planned, not an emergency, and recovery is quicker than the first surgery because the muscles are already rebuilt. Follow-up then continues as for any adult implant.
Can the implant be lengthened at a hospital nearer home?
Usually not. Lengthening needs the coil that matches the implant, the X-rays to check it and a team that knows the device. Physiotherapy in between can often be done locally, so ask your centre about that.
Does Aarogyasri or insurance cover a growing implant?
Cancer surgery is covered within scheme limits under Aarogyasri, CGHS, ECHS and EHS, and most cashless insurers are empanelled. Growing implants are costly and are often handled separately from the operation, so ask early. Call the helpline with your card and reports and we will check before you travel.
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MBBS (AIIMS), MS (Surgery) (AIIMS), DNB (Surgical Oncology), MRCS (Edinburgh)
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Dr. Vinay Mamidala
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Sources
- National Cancer Institute — Osteosarcoma and Undifferentiated Pleomorphic Sarcoma of Bone Treatment (PDQ)
- Cancer Research UK — Children's cancers
- American Cancer Society — Surgery for osteosarcoma
- NHS — Bone cancer: treatment
This page is general information, not a prescription. Do not change or stop any treatment based on what you read here. If anything is worrying you, contact your own treating team — or call our helpline and we will help you reach the right specialist.
Keep reading
Related pages
Rotationplasty ExplainedThe main alternative for a growing child, compared honestlyEndoprosthetic Replacement After Bone Tumour RemovalThe adult implant your child will eventually convert toHow Long Does an Endoprosthesis Last?Why implants in the young carry more operations over a lifetimeAmputation in Children and School LifeWhat the other path looks like for a child and a familyCaretaker and Family Guide to SurgeryWhat a family needs to arrange around a long pathway
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