All the useful information regarding common symptoms, treatment, surgical intervention and different types of hip prostheses. In the initial stages the condition is characterized by discomfort, intermittent pain and stiffness. During this phase the treatment is physiotherapy-focused, aiming to maintain mobility and strengthen muscles. Additionally, weight loss is recommended, along with the use of ice therapy combined with pharmacological treatments such as anti-inflammatories, cartilage supplements and joint injections.
As the disease progresses, it becomes impossible to engage in sports and daily activities such as walking or climbing stairs are limited. Pain may be present even at rest or during the night and it can become impossible to put on shoes or socks without assistance.
In advanced stages, unfortunately, conservative treatments are not effective and prosthetic surgery is necessary to alleviate symptoms, significantly reduce or remove pain and restore movement to the joint.
Surgery is advisable in the presence of any of the following symptoms:
- pain resistant to pain-relieving therapies
- limited joint mobility compromising daily activities
- significant difficulty rising from a seated position
- difficulty sleeping at night due to pain
- pain when walking
- no benefit or limited benefit from physiotherapy and conservative treatments.
HIP PROSTHESIS
Hip replacement is a complete joint replacement procedure in which the worn femoral head is removed and the acetabulum is milled to remove damaged cartilage and bone. It consists of two components: the femoral one and the acetabular one. The femoral component consists of a stem placed in the femoral canal, the neck and the head; the acetabular component consists of a cup.
THE STEPS OF THE SURGERY
- Administer anesthesia and, in agreement with the patient, provide sedation to ensure comfort during the procedure;
- Perform the surgical incision;
- Remove damaged cartilage and bone and prepare the joint ends for the implantation of prosthetic components;
- Secure the prosthetic components to the bone in the correct position;
- Test the new joint;
- Close the incision.
POSTERIOR SURGICAL APPROACH
There are two main surgical approaches to the hip: posterior and anterior. Both surgical techniques have the same goal, that is to restore functionality to the joint. The prosthesis used is the same, what changes is the surgical approach to reach the joint and the position of the scar: anterior, in front of the hip, or postero-lateral, just behind the hip.
Personally, I prefer using the posterior approach because, in my experience, it has some advantages:
- it can be used on all patients;
- the incision is small, posterior, and minimally noticeable;
- post-operative pain is low;
- it has been a successful surgical approach for many years;
- it provides excellent visualization of bone structures.
CEMENTED HIP PROSTHESIS
Cemented hip prostheses are indicated for patients with osteoporosis, elderly patients, or in cases of particular anatomical configurations.
In cemented prosthesis the femoral canal is filled with cement, and the stem is firmly fixed in place by the cement, which completely surrounds it; to prevent the cement from invading the entire femoral canal a plug made of absorbable material is placed. More rarely the acetabular component can also be cemented.
Fixation with cement is extremely stable. Once the plug is positioned, the cement is inserted under pressure into the femoral canal. Subsequently the stem is inserted into the desired position and held in place until the cement completes polymerization, hardening and locking the prosthesis firmly in place.
The fixation is extremely strong from the outset, allowing immediate mobilization of the patient.
NON-CEMENTED HIP PROSTHESIS
It is indicated for young patients or those with good bone quality and regular anatomical conformation.
The non-cemented hip prosthesis is coated or composed of materials that facilitate integration with the surrounding bone tissue. Initially the prosthesis is firmly anchored in the bone and in a subsequent phase it will integrate with the surrounding bone tissue: depending on the surface of the prosthesis bone may grow onto or around the prosthesis, or it may grow within the material of which the prosthesis is composed or coated. This allows for a secure anchoring of the prosthesis in the planned position and theoretically results in a biological and more physiological fixation.
There are various types of stems available, both in design and fixation characteristics. The study of preoperative X-rays is essential for choosing the correct stem.
MINIMALLY INVASIVE HIP PROSTHESIS
Traditional hip surgery requires an incision of 20-30 centimeters and a healing period of 3 to 4 months. However, in the last decade, minimally invasive techniques have been developed that allow for successful implantation of the same clinically proven hip prostheses through smaller incisions. By cutting a smaller portion of skin compared to traditional surgery and involving muscles to a lesser extent, the minimally invasive technique alleviates pain, restores mobility and allows for a rapid return to normal life.
THE DIFFERENT MATERIALS OF HIP PROSTHESIS
The femoral stem ends with the neck, on which the new femoral head is applied, which can be made of metal alloy or ceramic. The acetabular cup similarly includes an insert made of polyethylene, ceramic or metal.
- Ceramic on Polyethylene: modern polyethylenes, termed “cross-linked,” ensure excellent long-term durability, especially when paired with a ceramic head. This is the most successful and widely used coupling, largely replacing the metal head with polyethylene acetabular insert combination;
- Metal on Metal: this pairing has raised concerns over time, making it a combination reserved for extremely selected cases;
- Ceramic on Ceramic: the latest-generation ceramic used in prosthetic surgery is called Delta. It is extremely smooth, wear-resistant and allows for the use of larger heads, which can reduce the risk of dislocation. One concern regarding ceramic on ceramic coupling is the possibility of fracture, which is extremely rare with modern materials. Another concern is the noise produced during joint movement by the contact between the two ceramic surfaces; this is a rare issue, sometimes associated with implant misplacement.
THE HEAD SIZE
Increasing the size of the head theoretically reduces the risk of hip dislocation by decreasing the chance of the femoral component coming into contact with the acetabular rim (impingement). However, a larger head size may cause a modest increase in wear of the prosthetic surface, especially when the acetabular insert is made of polyethylene.
The decision regarding the type of material to use should be based on the patient’s age and lifestyle.
For the success of the surgery, regardless of the materials used, the correct positioning of the prosthetic components is crucial. This ensures the stability of the implant and the correct balancing of soft tissues. Incorrect positioning can compromise the long-term durability of the implant, as can cause abnormal or excessive activity by the patient.
