Osseointegration after Amputation, Cambridge

With traditional socket prostheses, some patients have a poor fit between their residual limb and the prostheses, despite multiple adjustments. This is because there can be significant changes in the size and shape of their stump in the first 24 months after amputation.

The most commonly reported problems with standard socket type prosthesis are:

• Heat or sweating in the prosthetic socket – Can cause discomfort and affect prosthesis fit.
• Sores or skin irritation from the socket – Friction and pressure can lead to painful skin issues.
• Inability to walk in woods and open fields – Uneven terrain can be difficult to navigate with a socket prosthesis.
• Inability to walk quickly – Socket prostheses can limit mobility and speed.
• Pain in the residual limb – Pressure and movement within the socket can cause persistent pain.

As a direct consequence of the above problems, certain amputees cannot use their prostheses more than a few hours per day and quite often not even on a daily basis.

Apart from physical problems with the socket type prostheses, which are related in a majority of the cases to socket-skin interface, people will also notice:

• Slower walking pace and
• Increased tiredness.

Both consequences are as a direct consequence of increased energy consumption (oxygen consumption) which is very likely directly related to the level of amputation in the lower limb.

Patient having problems with conventional socket prostheses like:

• Discomfort, pain, or poor suspension – Difficulty using conventional socket prostheses.
• Recurrent skin infections and ulceration – Issues such as a short stump, soft-tissue scarring, volume fluctuation, extensive skin grafting, or excessive perspiration causing socket retention problems.
• Expected challenges with conventional prosthesis – Patients who are likely to struggle with socket-based solutions.

In addition to the above, patients must:

• Full skeletal maturity – Osseointegration is not suitable for children.
• Normal skeletal anatomy – The bone structure must be typical for successful implantation.
• Aged between 18 and 70 years old – The procedure is generally limited to this age range.
• Medically suitable for surgery – Patients must be in good health, with no significant underlying medical conditions.
• Commitment to treatment and follow-up – Compliance with the rehabilitation program and follow-up care is essential.

Osseointegration  surgery is very safe for all types of amputation, however like all surgery it is important to be aware of the possible complications. The main complications related to osseointegration procedure are:

• Infection (deep and superficial)
• Periprosthetic fracture
• Aseptic loosening

Superficial infection:

Many patients who undergo osseointegration surgery will experience superficial infections which can present with pain, redness, swelling and discharge from around the stoma. These are referred to as ‘superficial’ as they only involve the skin and subcutaneous tissues and the bacterial has not penetrated deeper inside the limb. Depending on the severity of the infection and type of bacteria involved, this infection will be treated with oral or intravenous antibiotics.

It is well accepted that superficial infection rate is 100%, meaning that it is extremely likely that every osseointegrated implant patient will experience this complication at least once, therefore every single patient we treat at our Cambridge clinic has to be aware of it but also be able to recognise early signs and react upon them as soon as possible. Even a few hours delay can result in prolonged treatment and increased pain.

Deep infections:

Deep infections are not as common with osseointegration. Deep infections are ones which have penetrated deeper into the limb and can involve the bone and prosthesis. Around 20% of patients will experience deep infection/osteomyelitis (infection of the bone) in the first 10 years post osseointegration. Almost half of them (9% of all patients) will need their implant removed and be treated for osteomyelitis. If the osteomyelitis is successfully treated, the stem can be reinserted.

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Periprosthetic fractures:

Periprosthetic fractures, or fractures in the bone around the osseointegrated implant prosthetic, can happen during the insertion of the implant into the bone during surgery or can happen at a later stage, mainly because of a fall or other traumatic incident. The incidence of periprosthetic fractures is between 10-25%. The fractures are treated using standard implants for bone fracture fixation, only in specific cases, custom made implants must be used for the osseointegration process.

Aseptic loosening:

Aseptic loosening is when there is the failure of the bond between an osseointegrated implant and amputated bone in the absence of infection. Aseptic loosening is a complication in many forms of orthopaedic surgery, including for example hip replacement surgery.

It is not clear if aseptic loosening is not actually a low-grade infection. Treatment involves the removal of the implant and microbiological evaluation of the samples from the medullary canal taken during the surgery. If all samples are negative, the stem can be re-inserted earlier otherwise we will follow the same pathway as in confirmed deep infection cases.