the different types of “made-to-measure” prostheses


It consists of the progressive degeneration of articular cartilage and most often affects women and people over the age of 50.

Whatever the causes, it leads to a loss of motor capacity and a feeling of daily pain of varying intensity for the patient.

While the treatment of knee osteoarthritis in the early stages involves the use of anti-inflammatories and physical therapy, when osteoarthritis progresses to a severe degree the only solution is knee replacement surgery.

When should you undergo knee replacement surgery?

Knee replacement surgery is recommended when one or both of these conditions occur and the patient

  • feels severe pain when moving the joint;
  • complains of stiffness that limits daily activities, including walking, climbing stairs, and standing or sitting in a chair.

The most common cause of this type of manifestation is osteoarthritis of the knee, the most common and widespread form of osteoarthritis, a chronic disease caused by the degeneration of articular cartilage.

It leads to injuries that gradually cause pain, difficulty in movement and, in the most severe cases, deformity of the joint itself (valgus, varus or bent knee).

How to choose a knee prosthesis?

In the collective imagination, the surgical treatment of knee pain consists of implanting a total knee prosthesis.

Today, however, this picture is no longer entirely correct, because in prosthetic surgery there are different types of knee implants.

  • monocompartmental prostheses
  • combined (mono + patellofemoral);
  • bi-monocompartmental prostheses;
  • total dentures.

Within the same category of total prostheses, there are different types depending on the design, the degree of invasiveness and constraint, and with a different biomechanical basis.

It is therefore up to the orthopedic surgeon to choose the individual implant type according to

  • a qualitative and quantitative assessment of the type of osteoarthritis;
  • functional expectations of each patient.

Good logic, in fact, should be to strike the right balance between:

  • degree and type of osteoarthritic degeneration of the individual patient;
  • type of implant available;
  • functional needs and expectations of patients.

Monocompartmental and bi-monocompartmental knee prosthesis

The monocompartmental prosthesis may be indicated if the osteoarthritis affects only part of the 3 compartments of the knee joint and its cruciate ligaments are present and valid.

This type of prosthesis has the particularity, unlike the total prosthesis, of replacing only the damaged part of the joint.

The principle of this minimally invasive choice is to ensure the preservation of the structural integrity of the knee, with less impact perceived by patients and therefore a higher level of satisfaction.

The monocompartmental prosthesis abroad has a 30-year history, but in Italy it is in the last 15 years that its application has become more frequent: the use of high quality materials, advances in engineering biomedical and surgical techniques have allowed surgeons to obtain increasingly satisfactory results, so much so that this type of “third generation” prosthesis is now widely used in minimally invasive prosthetic surgery.

The advantages of implanting this smaller prosthesis are considerable and are

  • less clinical impact on the patient
  • greater respect for the surrounding tissues and muscles;
  • better clinical outcome;
  • certainly better functioning in biomechanical terms.

Today, in fact, this type of prosthetic implant is considered a safe and reliable procedure that guarantees long-term success.

In special cases, it is also possible to simultaneously implant 2 monocompartmental prostheses in the knee, to replace 2 of the 3 knee compartments damaged by osteoarthritis. In this case, we speak of a bi-monocompartmental prosthesis.

Total knee prosthesis

If the surgeon has assessed that there is no indication for the use of the available range of compartmental prostheses due to excessive joint degeneration in the 3 compartments of the knee, he resorts to the implantation of a total knee prosthesis.

Thus, there are total knee prostheses that preserve the anterior and posterior cruciate ligament or only the posterior cruciate ligament, and those that involve the replacement of both.

What is a “made-to-measure” prosthesis?

It is essential that the surgeon, after having analyzed the degree of damage to the joint, builds the implant to be made, personalizing it on the patient and choosing the type of prosthesis best suited to his particular case.

In this sense, the prosthesis is personalized: not so much because it is molded to the anatomical characteristics of the patient, but because it is directly focused on solving the specific problem of the person affected by the pathology at the origin of joint degeneration.

What material is a knee prosthesis made of?

The prostheses are made of titanium, with a chrome-cobalt surface coating.

There are versions of prostheses with a ceramic metallic coating, specially designed to reduce the risk of potential allergic reactions to the nickel present in the cobalt chrome alloy.

In its middle part, the prosthesis insert is made of highly cross-linked polyethylene, sometimes enriched with vitamin E, which makes it more resistant to wear.

How long does a prosthesis last?

A knee prosthesis lasts on average about 15 years, but it is not uncommon to see implants still in excellent condition after 20 or even 25 years.

The wear of the prosthetic materials is not only related to the wear of the prosthetic components, but is influenced by other factors related to the quality of the bone and the lifestyle of the patient.

Surgical techniques and increasingly advanced materials make it possible to increase the durability of prostheses and therefore patient satisfaction.

However, in case of wear, the implant loosens, which requires a revision of the implant.

Robotic surgery: when it’s needed

Robotic surgery supports knee implant operations and is used by surgeons to be as accurate and precise as possible.

The robot is adjusted by the surgeon in the preparation phase and offers the advantage of eliminating the margin of error associated with the use of traditional instruments when performing planned bone cuts.

Also with robotic surgery, it is possible to perform combined mono or bi-compartmental and total prosthesis operations, depending on the damage of each patient, which allows the treatment to be adapted to the individual pathology.

Read also :

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What are knee cartilage injuries

Knee sprains and meniscal lesions: how to treat them?

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Knee ligament rupture: symptoms and causes

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Knee sprains and meniscal lesions: how to treat them?

Meniscus Injury: Symptoms, Treatment and Recovery Time



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