Emergency Care For Acute Arthroplasty Dislocation: Strategies and Considerations

Introduction:

When a hip dislocation occurs, doctors first focus on life-threatening injuries. Once these are ruled out or treated, they examine the hip. Pain relief and sedation are provided, and X-rays are taken. The hip is then gently put back into place using sedation. If unsuccessful, a computed tomography (CT) scan is done to determine the reason. Surgery may be necessary for some patients. After the hip is back in place, the legs are immobilized. Patients admitted to the hospital may need pain medication and are usually non-ambulatory. The duration of leg immobilization varies, but early weight-bearing can have complications. Some patients may be transferred to another facility for further care, depending on their condition.

What Are the Types of Acute Athroplastic Dislocation?

When the hip gets dislocated, the thigh bone gets pushed backward or forward out of its socket.

• Posterior Dislocation (Backward): In about 90 percent of cases, the thigh bone moves backward from its socket. When this occurs, the lower leg stays fixed, and the knee and foot turn inward.

• Anterior Dislocation (Forward): The thigh bone can sometimes slide forward out of its socket. In this case, the hip is slightly bent, and the knee and foot turn outward.

When the hip dislocates, it affects the bones and damages the ligaments, muscles, and other soft tissues that hold everything in place. It can also harm the nearby nerves.

What Are the Predisposing Factors of Acute Athroplastic Dislocation?

Age: Age does not play a role in the risk of hip dislocation after surgery. People who experience hip dislocation tend to be of similar ages to those who undergo hip replacement surgery.

Sex: Women are more likely to experience hip dislocation after surgery compared to men. In some studies, the ratio of women to men with hip dislocation was two to one, and in later dislocations (occurring five or more years after surgery), this ratio was even higher at three to one.

Height and Weight: Whether being taller or heavier increases the risk of hip dislocation needs to be clarified. More data is needed to support this idea, and the importance of these factors remains uncertain.

Medical History: Patients with a history of neuromuscular conditions or mental confusion appear to have a higher risk of postoperative hip dislocation. Conditions like alcoholism, uremic psychosis, senile dementia, cerebral palsy, and muscular dystrophy were more common in patients with hip dislocation.

Underlying Hip Condition: There is conflicting evidence about whether the original hip condition affects the risk of hip dislocation after surgery. While some studies found no association, others showed a higher dislocation rate in patients with fractures, congenital dislocation, and avascular necrosis.

Previous Hip Surgery: Having had prior hip surgery significantly increases the risk of postoperative hip dislocation. Patients with previous surgery had a higher incidence of dislocation than those without prior surgery. Extensive soft tissue work or bone removal during surgery also raised the risk of dislocation. So, previous hip surgery is a major risk factor for hip dislocation after the operation.

What Are the Indications for Open Reduction?

• If the hip dislocation cannot be put back into place (rare).

• If the joint remains unstable even after it is put back.

• If there is a fracture in the hip bone.

• If there are nerve or blood vessel problems after the dislocation is fixed.

How Is Acute Arthroplasty Dislocation Managed in the Emergency Department?

1. Pain Relief:

• Pain relief is crucial for a patient’s comfort and recovery.

• The chosen pain relief medication should work quickly, predictably, and adjust easily.

Types of Pain Medications:

• Morphine sulfate is a commonly used pain medication because it works reliably, has a good safety record, and can be reversed if needed.

• Fentanyl citrate is a stronger pain medication than morphine and is suitable for sedation during procedures. It has a shorter duration and can be easily adjusted.

• Meperidine is another pain medication similar to morphine but may have fewer side effects like constipation and muscle spasms.

2. Sedation for Procedures:

• Sometimes, doctors need to sedate patients for procedures like putting the hip back in place.

• Policies should be in place to specify who can give sedation medications, who must monitor the patient, which medications and doses to use, and what emergency resources should be available.

Goals of Sedation:

• When sedating a patient, the goals include relieving pain, relaxing muscles, and helping the patient forget the procedure.

3. General Anesthesia May Be Necessary:

• For some patients, especially if the hip dislocation is complicated, general anesthesia in the operating room may be needed.

• This is usually required when the hip can't be put back in place without surgery or when significant fractures or nerve injuries are associated with the dislocation.

4. Reducing the Dislocated Hip:

• To fix the dislocated hip, the patients will receive medication to make them comfortable, and a specialist will carefully move the hip bones back into their proper position. This is called a "reduction."

Types of Reduction:

• Sometimes, the reduction is done in an operating room with anesthesia. In rare cases, surgery is needed when torn tissues or small bone pieces block the hip from returning to place. Surgery removes these obstacles and aligns the bones correctly.

Checking the Results:

• After the reduction, the doctor will take more X-rays and may do a CT scan to ensure the bones are in the right position.

5. Treatment Without Surgery:

• The patient might not need surgery if the hip joint is put back in place without any associated fractures. However, the patient will not be able to put weight on the leg for six to ten weeks, and will need to be cautious about certain leg positions as it heals.

6. Surgical Treatment:

• Surgery might be necessary if there are fractures along with the dislocation or if the hip remains unstable even after the reduction. Surgery aims to stabilize the hip joint and restore the cartilage surfaces to their normal positions. This type of surgery usually requires a large incision and can result in significant blood loss. Some patients may need a blood transfusion during or after the surgery.

What Are the Possible Complications of Hip Dislocation?

• Avascular necrosis (AVN) of the hip, which can occur in 8 to 13 percent of patients. Early treatment reduces the risk of AVN. The impact of early weight-bearing on AVN is debated, but it may lead to more severe cases without increasing the overall risk. AVN risk is higher with delayed reduction, multiple reduction attempts, or surgery.

• Sciatic nerve injury (in posterior dislocation) affects 10 to 14 percent of patients. Doctors check for sciatic nerve problems before and after fixing the dislocation. If there's an issue, surgery may be needed.

• In anterior dislocation, a femoral artery or nerve injury is likely. Children can experience dislocation with minor injuries, so gentle reduction is essential to prevent further damage, especially to the femoral epiphysis.

Other Complications:

• Osteoarthritis, meaning damage to the hip joint, can lead to arthritis over time.

• Heterotopic calcification (abnormal bone growth in soft tissues).

• Repeated dislocations.

• Knee ligament injuries or other fractures.

• Problems from immobility, like blood clots (DVT), lung blockages (pulmonary embolism), bedsores (decubiti), and pneumonia.

• In anterior dislocation, there's a risk of damaging the femoral artery.

What Are the Differential Diagnosis of Hip Dislocation?

• Abdominal trauma.

• Femoral shaft fractures in emergency medicine.

• Hip fracture.

• Legg-Calve-Perthes disease.

• Pediatric limp.

• Pelvic fracture management.

Conclusions:

After a total hip replacement, it is crucial to prevent dislocation. This involves assessing risks before surgery and ensuring the right operation with proper alignment, tissue balance, and component ratios. If instability occurs post-surgery, there is a set plan for treatment. Dislocation can be distressing for patients, affecting their trust in the artificial joint and the goal of having a joint that feels natural and trouble-free.