Definition and Overview

Hip joint replacement is an orthopaedic surgical procedure used to replace the hip’s ball-and-socket joint with a prosthetic implant. It can be recommended as the last resort for the treatment of chronic and debilitating joint pain caused by arthritis, hip dislocation, and certain hip abnormalities. The procedure offers long-lasting pain relief, increased mobility, and improved quality of life in both the medium and long term.

Advances and new technologies in surgical techniques have greatly reduced the risks and complications associated with hip joint replacement surgery. However, dislocation of the hip prosthesis still occurs in about 2-10% of patients. This complication can be caused by many factors including impaired compliance, accompanying neurologic diseases, the patient’s advanced age, insufficient soft-tissue tension, infection, and the surgeon’s lack of enough experience, among others.

The dislocation of hip joint prosthesis may require revision surgery, which involves removing some or all of the parts of the implant used. When compared to the initial procedure, revision surgery is far more complicated because most cases involve damage to the supporting bone and surrounding soft tissue, which can increase the risk of another dislocation.

Cause of Condition

The hip joint prosthesis can be displaced due to:

  • Patient-related factors - A higher dislocation incidence of up to 8% was observed in patients with neuromuscular conditions, including but not limited to Parkinson’s disease, cerebral palsy, dementia, and muscular dystrophy. The risk is also higher in elderly patients who are more prone to falls and those who do not comply with postoperative rehabilitation.

  • Procedure-related factors - These factors include the surgical approach used and the surgeon’s qualifications and experience. An analysis of more than 13,000 primary total hip replacement surgeries has shown that using the posterior approach poses a greater dislocation risk than anterior, anterolateral, and lateral approaches. The surgeon’s experience is another factor that influences dislocation rates. According to a study, orthopaedic surgeons who had performed less than 30 hip joint replacements had a double rate of dislocations than more experienced surgeons.

  • Implant-related factors - The proper positioning and design of the artificial joint prosthesis can improve stability and lower the risk of dislocation as well as other complications.

Key Symptoms

The risk of hip joint prosthesis from becoming dislocated is higher within the first three months of surgery when the muscles and ligaments are still healing. When this happens, the following symptoms can be observed:

  • A snapping or popping sound at the moment of dislocation

  • The affected leg appears to be shorter or longer than the other leg

  • The affected leg is twisted outward

  • A feeling that the hip bone has slipped out of joint

  • Inability to bear weight on the affected hip or leg

  • Pain in the affected upper leg, buttock, and hip

  • Severe pain in the groin area

Who to See and Types of Treatments Available

Patients whose hip joint prosthesis has become dislocated must consult an orthopaedic surgeon for treatment.

To assess the condition and determine the best course of treatment, the following procedures are often performed:

  • Physical examination of the affected hip or leg

  • A thorough medical interview in which the patient is asked about the circumstances that led to the dislocation and whether it is the first time that it occurred

  • Laboratory tests - To confirm or rule out inflammation and/or infection as the cause of the condition

  • Imaging tests such as bone scan and computed tomography (CT) scan – To determine if the implant has loosened or if the patient has fractures

  • Joint aspiration

In some cases, the dislocated hip prosthesis can be manipulated back into its proper place through closed reduction, a non-operative procedure performed without a surgical incision or instruments. For the procedure, the patient is given local anaesthesia as well as sedatives and muscle relaxants. The doctor will then stabilise the patient’s pelvis, apply traction to the lower extremity, and gently rotate the thigh to move the femoral head back into its proper location within the acetabulum.

If closed reduction is not an option, hip revision surgery, which involves replacing the prosthesis used during the primary surgery, is recommended. It is performed the same way as the primary surgery but it is more complicated, unpredictable, and often takes longer because there is almost always bone loss around the primary prosthesis. Thus, it is common for surgeons to reinforce the bone using a bone graft, which can be taken from the patient’s body or a bone bank (allograft).

The surgery to replace a dislocated hip prosthesis carries certain risks and complications, including:

  • Adverse reaction to the anaesthetic used

  • Blood clot formation, which can lead to pulmonary embolism

  • Repeat dislocation - There is no guarantee that the revised artificial joint will not be dislocated again after revision surgery. In fact, the risk of dislocation, as well as infection, is higher in repeat procedures.

  • Loosening of the artificial hip joint

  • Myositis ossificans - A condition in which the bone forms around the hip joint, causing it to become stiff.

In some cases, revision hip surgery cannot be recommended, such as in cases of severe infection, significant bone loss, or if the patient has other medical conditions that make him or her unfit for the procedure. By not replacing the dislocated joint, the patient may not be able to walk again.

References:

  • Iorio R, Robb WJ, Healy WL, et al. Orthopaedic surgeon workforce and volume assessment for total hip and knee replacement in the United States: preparing for an epidemic. J Bone Joint Surg. 2008;90:1598–1605.

  • Parvizi J, Picinic E, Sharkey PF. Revision total hip arthroplasty for instability: surgical techniques and principles. J Bone Joint Surg. 2008;90:1134–1142.

  • Zwartelé RE, Brand R, Doets HC. Increased risk of dislocation after primary total hip arthroplasty in inflammatory arthritis: a prospective observational study of 410 hips. Acta Orthop Scand. 2004;75:684–690.

Share This Information: