The Role of the Learning Curve in Surgery for the Implant’s Survival
Prosthetic surgery, regardless of the anatomical area, benefits from large volumes of procedures.
It is universally accepted and supported by scientific evidence that reference centers, and specifically high-volume surgical teams within these centers, play a central role in prosthetic surgery. They are key not only in managing the initial prosthetic implant and its revision but also in training specialized surgeons.
Numerous scientific studies have been dedicated to the concept of the "learning curve"—the process by which a surgeon becomes fully proficient and reliable in performing a specific surgical procedure, particularly in the context of prosthetic implants.
In the field of ankle prosthesis and learning curves, my team, one of the pioneers in this area, has conducted and published several key studies: “Identifying the Learning Curve for Total Ankle Replacement Using a Mobile Bearing Prosthesis” (published in the European Journal of Chirurgia della Caviglia e del Piede: Foot and Ankle Surgery) and “Pearls and Pitfalls for a Surgeon New to Ankle Replacements” (published in Foot and Ankle Clinics).
Through these studies, we were able to identify, for the first time, a specific cut-off point at which a surgeon specializing in ankle prosthetic surgery can be considered to have completed their learning curve.
According to our published data, a surgeon can be considered an expert in the field after performing 30 cases.
However, the total number of cases is not the only factor; the number of cases performed per year is also crucial, as it defines the surgeon’s ongoing practice in prosthetic surgery.
In recent years, reference centers both in Italy and globally have been focusing on the establishment of Prosthetic Registries. These registries track key data, including:
- The number of surgeries performed
- The types of prostheses implanted
- The revision rates
However, the data can often prove to be sterile and difficult to interpret. This is a topic we recently addressed in one of our studies, published in the European Ankle and Foot Surgery journal.
To meet these modern needs, the Institute where I worked for 10 years, IRCCS Galeazzi, pioneered the creation of a prosthetic surgery registry. In this registry, alongside traditional data, we also collect objective data and assessment scales administered by the surgeon, as well as patient-reported outcomes (PROMS) related to satisfaction and the perception of the surgery.
The novelty and significance of this initiative lie in its ultimate benefit to both science and patients. It is driven by the goal of studying and understanding ankle arthritis and the role of ankle prostheses.
From the outset, it has been a source of pride for me to serve on the Board of this prosthetic registry. I believe it is an ethically necessary commitment to our patients—both past, present, and future.
Causes of Failure
X-rays of a new prosthesis (from right to left; lateral, frontal, and posterior views)
The failure of an ankle replacement surgery can happen for several reasons, typically falling into three main categories:
- Prosthetic Implant Failure
- Implant Mobilization and Peri-prosthetic Fractures
- Infection
Infection, in particular, has its own distinct history and requires different protocols compared to the other two failure causes. This is a topic we have thoroughly explored in our studies, aiming to provide patients with reliable alternatives and better management strategies.
È, quindi, un argomento su cui abbiamo pubblicato, proponendo la nostra strategia terapeutica in un nostro articolo sulla rivista europea di chirurgia della caviglia e del piede: “Infections in primary total ankle replacement: Anterior approach versus lateral transfibular approach”.
The treatment primarily focuses on addressing and healing the infection.
In the case of an acute infection (occurring within the first 6 months after surgery), the initial surgical procedure is typically followed by a specific combined antibiotic therapy, which usually lasts from 2 to 3 months.
If the infection is chronic (lasting over 6 months), or if the previous treatment has not been effective, the standard procedure involves the removal of the prosthesis, which is then replaced with a spacer implant made of antibiotic cement.
It is usually possible for the patient to bear weight on the spacer within a month after surgery. If the patient is satisfied, the spacer can remain in place for the rest of their life. However, if the patient is considered to have recovered from the infection but continues to experience pain, a revision procedure may be recommended.
Once clinical recovery is achieved and if there is sufficient bone-stock (residual bone), a new prosthesis can be implanted.
In cases where the failure is due to either prosthetic implant failure or implant mobilization/peri-prosthetic fractures, two distinct revision strategies can be identified, depending on the amount of residual bone available in the talus.
If the amount of healthy bone at the talus level is sufficient, it is advisable to replace the failed prosthesis with another "first implant" prosthesis, rather than using a revision implant.
The advantage of this approach is that it helps conserve bone, reduces the invasiveness of the procedure, and preserves the option for a second revision if necessary in the future.
In these cases, the lateral approach is particularly beneficial because it provides the surgeon with a broader and more direct view of the joint, avoiding previous scars and deep adhesions. This approach allows for the removal of the initial implant and a revision that prioritizes biological economy, meaning that as much bone as possible is preserved.
If the residual bone-stock is insufficient, modern revision systems offer excellent possibilities. These include replacing the talus entirely with talus prostheses or custom-made prostheses, offering viable solutions even when there is limited bone remaining.
These are advancements driven by technology across various fields. Three-dimensional printers and vision systems now enable the creation of instruments specifically tailored to address the pathology or skeletal defect of each individual patient. This level of customization helps optimize treatment outcomes, offering more precise and personalized solutions for complex medical conditions.
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