Artificial Hips : Revision of unhappy hip prosthesis

When can you intervene on a hip prosthesis?

Operating on an already replaced hip is possible under two circumstances:

• Either at the end of the normal wear and tear of the implants, many years after their placement.
• Or in case of dysfunction of the prosthesis.

In all cases, the revision is preceded by a rigorous diagnostic approach specifying the state of the muscles and tendons, the quality of the bone stock and the prosthetic fixation, the positioning of the implants and their wear, the references of the implanted prosthesis, and the surgical approach used during the placement. The diagnosis of infection is rare but must be considered in case of atypical dysfunction.

Technically, various surgical solutions are possible in a gradual way:

• Intervention on muscles, tendons, soft tissues or calcifications without modifying the existing implants (e.g., tendon repair after Hardinge approach);
• Simple isolated change of one component, without touching the other prosthetic component (e.g., change of the acetabular cup for conflict with the psoas);
• Bipolar change of the acetabular implant and the femoral implant (e.g., bipolar loosening of the implants);
• Change with osteosynthesis or metallic reinforcement (e.g., pelvic osteolysis due to prosthesis wear);
• Change with bone reconstruction by graft (e.g., advanced periprosthetic bone destruction).

The duration of the surgery varies from one and a half to more than four hours depending on the situation. Hospitalization usually lasts six nights. Walking support can be immediate or delayed for six weeks in case of bone graft. In all cases, the goal is to restore a stable, mobile, and painless joint, allowing the resumption of activities without limitation.

Pain After Prosthesis

Hip Pain

Except in rare cases, persistent hip pain after a hip replacement is a sign of a dysfunction or injury and can be treated.

The diagnostic process begins by eliminating the causes of referred pain, such as sciatica, femoral neuralgia, hernia, or arterial insufficiency. Pain that is identical before and after hip replacement suggests an initial indication error.

The causes that are actually related to the hip are multiple:

• Conflict of the psoas tendon with a protrusion of the prosthesis;
• Rupture or inflammation of the gluteal tendons;
• Micromobility of the stem or cup, loosening;
• Periarticular ossification, muscle injury;
• Nerve injury (sciatic nerve, femoral nerve, lateral cutaneous nerve), algodystrophy;
• Surgical site infection;
• Tumorous lesion.

Regardless of the situation, it is important to persevere and find the cause of the pain through a complete clinical examination and exhaustive explorations. Reading the operative report is essential for diagnosing causes related to the surgical technique.

A second and even a third surgical opinion are also appropriate, as they can provide a fresh and experienced perspective. Pain of “psychiatric” origin should be considered as a diagnosis of exclusion, as the majority of the identified causes can be treated effectively with intervention.

Limping After Hip Prosthesis

A few weeks after implantation of a hip prosthesis, it is normally possible to walk without pain and limping. If this is not the case, different causes of dysfunction must be considered:

All causes of hip prosthesis pain can cause limping:

• Conflict with the psoas;
• Loosening of implants with or without infection;
• Tendonitis of the gluteals, trochanteric bursitis.

Other mechanical causes should be considered, especially a change in length or lateralization of the hip that alters the path of the muscles and sometimes renders them insufficient. A hip prosthesis followed by shortening or lengthening of the limb logically leads to limping.

Some limps are due to injury to the tendons/muscles during surgery: Hardinge transgluteal approach, trochanterotomy.

Finally, pains originating from other than the hip should be considered: neurological disorder, cruralgia.

Depending on the identified cause, treatment is usually possible, particularly for all mechanical causes. Repairing a tendon lesion, retensioning the muscles, or eliminating a painful phenomenon usually leads to the disappearance of the limp.

Psoas Tendinitis

The occurrence of psoas tendinitis after implantation of a hip prosthesis is a relatively frequent event, affecting more than 5% of cases.

It is an anterior, groin pain, usually not present before the surgery. The pain appears a few days or weeks after the surgery, then becomes disabling as it does not disappear despite rehabilitation. X-rays are usually interpreted as normal, the prosthesis seems to function well.

In reality, it is often due to a protrusion of the prosthetic cup in front, in contact with the irritated and inflamed psoas tendon due to this conflict. Hip flexion is painful, even impossible when the tendinitis is severe.

It is then appropriate to confirm the diagnosis with an ultrasound, which shows the protrusion of the cup, the contact with the tendon, and an inflammatory bursitis with tendon inflammation. If a cortisone ampoule is injected at the contact of the tendon, the pain disappears for a few weeks and then reappears. A hip CT scan can highlight this protrusion of the cup.

The treatment is based on one of these interventions:

• either a hip arthroscopy to cut the tendon (psoas tenotomy); 
• or a revision of the acetabular cup to implant a smaller cup away from the psoas tendon.

The result is usually excellent, with definitive disappearance of the tendinitis. Finally, it should be noted that some psoas tendinitis can also be due to a residual osteophyte, outside of any cup protrusion.

Hip Bursitis After Prosthesis

Bursitis is a small inflammatory and painful pouch filled with fluid, indicating the suffering of certain periarticular structures like tendons. Its occurrence after hip prosthesis is often associated with the presence of metallic sutures (prosthesis placement by trochanterotomy).

Another situation is the presence of a rupture of the gluteal tendons after Hardinge approach (transgluteal approach). Finally, there are certain cases of bursitis around osteophytes.

The diagnosis is made with a hip ultrasound. The treatment is primarily based on anti-inflammatories or on the puncture infiltration of the bursitis (cortisone).

In case of persistence, surgical intervention is necessary, and the cause of the inflammation must be removed: removal of irritating sutures, repair of damaged tendons, etc.

Wear of Hip Prosthesis

Any hip prosthesis implanted in the body is subject to wear and tear, as complete absence of friction and perfect lubrication do not exist. This wear, however, is very gradual and painless.

In some cases, however, the wear of a hip prosthesis is problematic and must be taken into account:

• Significant wear of the polyethylene prosthetic plastic (acetabular cup) can occur after several years, generating multiple debris whose evacuation is accompanied by bone destruction (osteolysis) around the prosthesis.
• Wear of the metal parts of the hip prosthesis is an abnormal phenomenon that can generate metallosis or even painful benign synovial tumor. This is the case with certain resurfacings, or prostheses with metal/metal pairs.

When the wear is isolated and minor, it should be monitored without intervention. When wear is accompanied by bone destruction or pain, it is necessary to promptly change the worn implants with new ones to preserve the bone capital.

In all cases, a hip prosthesis must be monitored by regular x-rays throughout life, as wear, even severe, is often completely painless.

Loosening of Hip Prosthesis

Hip prosthesis loosening refers to the development of movement between the artificial joint and the surrounding bone. This movement, which can be either painful or painless, is typically diagnosed through X-rays.

Several factors can lead to loosening:

• Normal wear and tear: Over time, even the most durable implants can wear, gradually leading to loosening.
• Early mechanical failure: In some cases, insufficient initial fixation can cause the implant to loosen prematurely.
• Infection: Bacterial contamination around the joint can also loosen the prosthesis.

Prompt action is crucial in all cases. Loosening progressively damages the bone surrounding the implant (osteolysis), making revision surgery necessary. This surgery involves replacing the loosened implant with a new one and taking tissue samples to rule out infection.

Dislocation of Hip Prosthesis

Hip prosthesis dislocation is often associated with the use of a posterior approach during prosthesis placement (Moore technique). Sectioning of the external rotator muscles increases the risk of dislocation, compared to the anterior hip approach which does not section any muscles. Dislocation, especially when repeated, is a traumatic event that requires emergency transport to the surgical department for reduction under anesthesia.

The diagnostic approach assesses the neuromuscular and general condition. It is necessary to take note of the operative report: approach, diameter of the prosthetic head, implant references. Malpositioning of the implants is sought on radiographs and on a CT scan. Wear is also assessed on x- rays. 

Treatment is based on surgical revision: repair of the external rotator muscles, change in the positioning of the implants, placement of a dual mobility cup.

Preventive treatment is based on a surgeon education program. The anterior approach without muscle section is a technique with a near-zero risk of dislocation and allows all movements without restriction.

Infection of Hip Prosthesis

Infection of a hip prosthesis is a serious event, with a frequency of less than 1% of implanted prostheses.

The diagnosis is based on a combination of factors: abnormal healing, discharge, general deterioration, fever, hip pain day and night, appearance of radiological signs of bone destruction around the prosthesis, an increase in biological markers of inflammation (white blood cells, sedimentation rate, CRP). Sometimes, the infection can be difficult to diagnose because the signs are mild or atypical.

Performing a biopsy puncture cultured under radiography is a good way to confirm the existence of a deep hip infection.

When the diagnosis is confirmed, it is imperative to consider surgical revision to clean and usually remove the infected implants. Antibiotic therapy is prolonged and should be initiated after the surgical procedure, based on the susceptibility of the responsible microorganism.

Preventing surgical site infections after hip surgery involves a set of actions: patient education and pre-operative screening for infections (dental or otherwise), antibiotic prophylaxis during surgery, surgical asepsis precautions, and the quality of post-operative care.

Hip Revision Surgery

Revision hip surgery is a complex and challenging procedure that is performed to address problems with a previously placed hip prosthesis.

There are two main types of revision hip surgery:

• Evident diagnosis: This type of surgery is performed to address a clear problem with the prosthesis, such as loosening or infection.
• Unclear diagnosis: This type of surgery is performed when the cause of the problem is not clear, even after extensive testing.

It is important to remember that a hip prosthesis should be stable, mobile, and pain-free. If your hip prosthesis is not meeting these criteria, it is likely that there is a problem that can be addressed with revision surgery.

Our team of surgeons is committed to providing solutions to complex and challenging hip problems.