Total Hip Replacement Dislocation

Original Editor - Lucinda hampton

Top Contributors - Lucinda hampton and Kim Jackson  

Introduction

Dislocated hip replacement

Total hip replacement (THR) dislocation is a complication of THR usually occurring due to patient noncomplicance with post-operative precautions, implant malposition, or soft-tissue deficiency. This type of dislocation normally caused by minimal trauma, usually falls or turning, moving into the contra-indicated positions, and putting stress on the capsule that was incised for the replacement surgery.

Epidemiology

Incidence: 1-3% with 70% occur within first month and 75-90% being posterior dislocations.

Risk Factors

Dislocated hip prosthesis

Following a THR the normal hip anatomy and support structures is altered. This violation may cause a decrease in the amount of inherent/anatomic force that assists in maintaining the femoral head within the acetabulum. Consequently the amount of energy necessary for a dislocation to occur is reduced.  Significant risk factors mechanically predisposing individuals with THRs to dislocation include:

• Surgical approach used, for example, anterior or posterior
• Kind of prosthesis (hemi or total arthroplasty)
• Previous hip surgery
• Female
• Malposition of the prosthesis during surgery
• Drug/alcohol abuse
• Neuromuscular disease for example Parkinson, Demetia. 
• Polyethylene wear, a common cause of late instability occurring >5 years after surgery.

Presentation

Typically the dislocation include falls, bending down to tie one's shoes, sitting on a low/short chair then trying to stand, or sitting, standing, or lying down with crossed legs. eg After a fall patient presents with a painful affected hip and shortened and internally rotated affected leg.

Diagnosis

Diagnosis is with plain x-rays of the hip. CT of the pelvis assists with assessing for implant malpositioning.

Treatment

Treatment is closed reduction of the hip. Surgical management with possible revision THA is advisable for irreducible dislocations, recurrent instability, and implant malposition.

Treatment of recurrent hip dislocation starts looking for the cause.

• Component position needs careful evaluated, as does hip offset and leg length.
• When planning a reconstruction, it is generally not a good idea to compensate for malposition of one component by overcorrecting the other.
• Patients needs to be informed that stability may require lengthening of the leg.

Roughly 66% of cases are successfully treated; one third of cases will require surgical treatment (including revision arthroplasty with use of constrained liners, elevated rim liners or dual mobility implants or trochanteric advancement)

Surgical options include exchange of modular components to increase soft-tissue tension, or a switch to a larger head diameter, including bipolar or tripolar arthroplasty, and use of an acetabular lip. Malposition and impingement must be corrected. Soft-tissue or trochanteric advancement, and the use of constrained liners should be a last resort.

Physiotherapy

This follows the same protocol as Total Hip Surgery (see link). Be aware however that the surgeon may have specific advice to follow, especially as this is a more complex procedure. The total rehabilitation phase in hospital and home may also be longer due to more extensive damage and repair.