Knee

With the advent of arthroscopy in the 80s, (minimally invasive surgical procedure that, through the use of fiber optic mini-cameras and dedicated instruments, allows for access to the joint without cutting it open), knee and shoulder surgeries were radically evolved.

After some decades of application and technological evolution, nearly all of the important joints can be treated arthroscopically. 

This has allowed for the treatment of many injuries with greatly reduced surgical trauma, thus favoring the healing and functional recovery process.

One of the most frequent injuries of the capsuloligamentous system of the knee is the sprain or breakage of the anterior cruciate ligament (ACL).

The most common causes are sports traumas (in high impact sports with elevated functional demands, such as football, basketball, etc).

There are different levels of severity for an ACL injury: from a simple sprain, to ligament elongation to a full tear.

Injuries to the anterior cruciate ligament (ACL) can require reconstructive intervention: this depends on various factors such as the severity of the injury (if it leads to instability), the age and activity level of the patient.

The ACL cannot be sutured; reconstruction is necessary using tendon grafts that act as a scaffold on which a new ligament will form.

The autologous grafts (taken from the patient himself) most frequently used are the patellar tendon and the tendons of the knee flexors (gracilis and semitendinous).  Homologus (cadaver) grafts can also be used.

Each source of grafts presents advantages and disadvantages; the choice of the type of transplant is made by the surgeon along with the patient on the basis of a careful evaluation.

The surgical technique consists of the preparation of 2 bone tunnels (tibial and femoral) into which the pre-prepared transplant is passed and then fixed with screws or pins (metal or re-absorbable material).

The post-surgical period calls for early movement of the joint and an intense, precise rehabilitation program.  The return to daily routine is relatively fast (about 10-15 days) while for intense sports or physical activity it can be up to 6 months.

Tears of the meniscus are some of the most common internal knee injuries. They can be degenerative or caused by trauma.  There are different types of tears: simple, bucket handle, flap, complex, etc.

If the injury is small, situated on the external border and symptoms are scarce with good knee stability, it could be treated conservatively without surgical intervention.  In the acute phase a period of rest, ice and anti-inflammatories are sufficient to alleviate symptoms. An exercise program to reinforce the thigh muscles is fundamental for functional recovery.

In cases where painful symptoms persist or in other specific cases, meniscal tears can be treated arthroscopically with excellent results. The more peripheral injuries (in the so-called “red-zone”) have the possibility to heal and for this reason can be sutured (in young patients).  The most common tears, however, happen in the more internal areas, which is less vascularized (“white zone”); as these areas do not have the possibility to scar, the broken part of the meniscus is simply removed.

In extremely selective cases and in young patients with important functional needs, meniscus transplants could be indicated.

There are three main reasons for cartilage injuries:

1. Arthrosis: this is the most common cause of suffering or injury to cartilage. It is a progressive degenerative disease in which the cartilage is consumed slowly with time. It normally affects middle-age or elderly patients.
2. Inflammatory arthritis: the most common is rheumatoid arthritis. These have a genetic predisposition and can occur at all ages.  They generally cause the destruction of most joints.
3. Post-traumatic: this can present itself after a knee injury. This type of chondropathy is similar to arthrosis and can develop years after a fracture, a ligament injury or a meniscus tear.

The injury to the cartilage causes pain, bruising and functional limitations that compromise normal daily life.

Conservative treatments (non-surgical), consisting in physical-rehabilitative therapies and infiltration therapies (ex. hyaluronic acid), can alleviate the symptoms, improve mobility and joint rigidity, but they cannot reconstruct the cartilage.

They are indicated in the early phases of the disorder, in cases in which patients cannot undergo major surgery or while the patient is waiting for surgery.

“Rescue” surgical interventions include:

• Osteotomies to correct axial deviations of the knee (varus or valgus) that cause uneven loads on the join surfaces, thus causing damage to the cartilage.

• shaving cartilage or chondroabrasion: this is an arthroscopic procedure that involves the cleaning of the ruined cartilage to make it smoother and to remove any movable bodies that could block the joints.

• microfractures: micro-perforations using arthroscopic instruments that, performed in the areas with cartilage defects, cause the underlying bone to bleed; during this process, stem cells are released that trigger a process of formation of a fiber-cartilage repairing tissue.

• Mosaicplasty: this is a technique that involves the removal of cartilage and bone cylinders from a non-load bearing area (blue arrows) of the patient suffering from focal chondral lesions and their “mosaic” implantation into the injured area (red arrow).

• Cartilage transplantation: in selected cases for small injuries and in young patients, this procedure can provide long-term benefits. In cases of autologous transplant, a small amount of cartilage is removed from the patient and sent to highly specialized labs, where it is cultured; the chondrocytes (joint cartilage cells) if suitably treated, can replicate to form a new cartilage that will then be implanted into the patient.

• Biomimetic scaffolds: the latest discovery of biotechnology, these are structures of hydroxyapatite and collagen that, when positioned at the site of the cartilage defect, act as a scaffold and allow autologous stem cells coming from the bone bleeding under the injury, to rebuild the cartilage.

A prosthetic replacement is necessary in all cases of severe injury in which symptoms are no longer controlled by palliative treatment.

It is one of the most accomplished orthopedic interventions and can give great and long-lasting results over time. This is to replace the knee sliding surfaces with a prosthesis made up of metallic and plastic materials. The prosthetic components are generally fixed to the bone by means of acrylic cement (polymethylmethacrylate).

There are various types of prostheses whose indication varies depending on the subjective pathological conditions of the patient.

Partial knee replacement

The knee is divided into three main compartments: the medial compartment (the inside of the knee), the lateral compartment (the outer part) and the patella-femoral compartment (the front of the knee between the femur and the kneecap). In selected cases, patients with a localized knee joint (usually internal or medial) can be candidates for a partial knee prosthesis where only the damaged knee portion is replaced by prosthetic components.

The advantages of this type of prosthesis are the less invasiveness, the preservation of ligaments and hence a more physiological biomechanical knee which results in faster recovery and better recovery of the function.

So called two-part prostheses (Duece) have also recently been introduced; they allow the replacement of both the patello-femoral and the medial compartment.

Total knee replacement (tkr)

This is the most common prothesis used.  It is defined as “coating” when the prothesis “covers” the joint heads from which the damaged cartilage and part of the underlying bone have been removed. Special cutting templates are applied to the tibia and femur and guide the bone resections so that the femur, the tibia and possibly the kneecap are prepared to accommodate the prosthesis.

Accurate preoperative planning through the study of anatomic and load axes is essential for preparing the femoral and tibial cuts and to reconstruct a normal and physiologically functional anatomy of the lower limb.

Through innovative software it is possible to measure not only the angles of the limb and the dimensions of the prosthesis, but it is also possible to forecast problems that could arise during the intervention and resolve them in advance.

The most modern technology allows us to improve the results and render them reproduceable through the use of navigators, robots or simply through the preparation of personalized cutting guides for each patient (PSI – Patient Specific Instrumentation) and produced by a 3D printer after a three-dimensional study done by CAT scan. These cutting templates, created specifically for that knee, allow for bone cuts exactly as planned on the PC in order to reproduce during surgery that which was previously and accurately planned.

Hinge prosthesis (stemmed)

These are used in revisions, in severe axial deviations or with marked instability of the knee. They allow for better anchorage and stability of the system. They are very invasive and for this reason are used only in very specific cases.

The decision to undergo prosthetic knee replacement should be made by the patient himself, along with his orthopedic surgeon, his general practitioner and his family on the basis of multiple factors; above all the symptoms that lead to this decision must be severe.

There are no absolute restrictions with regards to age or weight, but certainly the general conditions of the patient must be carefully evaluated.

An important factor in the final decision of whether or not to undergo this intervention is understanding that which you can and cannot do with a knee prosthesis. More than 90% of patients that undergo knee replacement report a drastic reduction in knee pain and a significant improvement in the ability to manage normal activities of daily life. But this intervention will not allow patients to do more than they used to be able to do before developing arthrosis.

Through normal use and activity, each prosthetic implant starts a normal course of wear of the polyethylene (plastic insert between the two metal components) that an increase in weight or excessive activity can accelerate and lead to an inevitable mobilization of the implant and thus the need for its revision (replacement). For this reason, most surgeons do not recommend activities such as running, jumping, or in general, all high-impact sports, for the rest of the patient’s life after surgery.

It is thus fundamental that the patient has realistic expectations before undergoing knee replacement surgery.

Currently, over 90% of the modern total knee prostheses are well-functioning 15 years after the surgical intervention.  By modifying lifestyle and activities (some of the activities permitted are unlimited walking, swimming, golf, light hiking, biking, ballroom dancing and other low-impact sports), you can contribute to the final success of your surgical intervention.

In order to help the prosthesis last as long as possible, it is important to constantly follow a program of muscular reinforcement and joint mobilization of the knee, take precautions to avoid trauma that could fracture the bone around the prosthesis (peri-prosthetic fractures), ensure that any infections or surgical procedures (especially in the case of dental procedures or surgeries) are adequately treated with proper antibiotics.

Periodic x-ray and clinical controls with your trusted orthopedic surgeon will ensure a proper monitoring of the implant’s progress over time.