One of the most common complications following a total hip replacement is dislocation, regardless of the surgical approach. Reasons for a dislocation can include implant position, bone and soft tissue impingement, soft tissue laxity and improper implant selection.
Dislocation after total hip replacement is the most common early complication following primary implantation. For example, the Swedish Hip Arthroplasty Register, considers dislocation to be the no.1 short-term complication requiring a re-operation within the first two years, while the Australian National Joint Replacement Registry (ANJRR) reports dislocation as a major reason for revision hip replacement surgery.
The incidence of dislocation after primary total hip replacement is reported from 0.2% – 1.7% according to the Swedish Hip Arthroplasty Register.
Examining the surgical techniques for a hip replacement, the posterior approach seems to be at a slightly higher risk for dislocation and possible early re-operation.
What is a hip
The articulation of the prosthetic head and the acetabular liner allow for a range of motion close to that of the intact anatomic hip. Dislocation occurs if the head moves out of the acetabular component for any reason.
Features of hip
Often, patients report a sudden onset of pain with a type of snapping feeling, followed by being unable to walk or load the affected leg. Occasionally the patient might describe a clunk followed by no pain indicating the hip had reduced itself.
Typical clinical signs of dislocation include leg shortening with either external or internal rotation, in combination with a pathologic and painful telescoping of the limb. X-rays are required for an accurate diagnosis.
The best option to ‘treat’ dislocation following a hip replacement is to prevent the occurrence in the first instance. Systems are available to the surgeon to improve cup and stem placement at operation.
At sportsmed, technology such as the Optimized Positioning System (OPS) developed by the Corin Group – a leading manufacturer and supplier of orthopaedic prosthesis – is used to aid the surgeon to improve outcomes for patients. The dynamic system measures pelvic position and combined implant position.
Appropriate implant head size and neck length are to be chosen. In case of instability, a retainment ring can provide more stability and be a suitable option. In addition, most implant companies now offer lipped liners as options. At pre-operative planning, the centre of rotation should be determined and during the surgery restored to fulfil the biomechanical environment of the hip.
Dislocation of a hip is a painful condition – patients are usually unable to walk. Closed reduction is carried out as soon as possible after diagnosis to avoid neurologic injury (1). Optimally, general anaesthesia and fluoroscopy are required, and commonly, two surgeons are on hand to safely perform the reduction manoeuvre (2). Before the procedure, the mechanism and reason for dislocation should be analysed.
If closed reduction fails or re-dislocation occurs within several days after the reduction, open reduction is to be considered (3). Before surgery, all possible reasons for the dislocation should be identified and the proper treatment option should be chosen.
In instances where dislocation with massive hematoma formation and/or palsy of the femoral or sciatic nerve occur, open reduction is mandatory within several hours. At open surgery, the fluid or hematoma is removed to decrease the joint tension. The membrane in and around the joint is debrided to encourage the soft tissues to form a new pseudocapsule which provides more stability.
A posterior soft tissue repair is considered and carried out if possible to prevent the joint from re-dislocating.
For all appointments and enquiries with Dr Spriggins, contact his direct line on 08 8130 1224.
1. Gaines RJ, Hardenbrook M. Closed reduction of a dislocated total hip arthroplasty with a constrained acetabular component. Am J Orthop. 2009;38:523–5, www.ncbi.nlm.nih.gov/pubmed/20011742
2. Schafer SJ, Anglen JO. The East Baltimore Lift: a simple and effective method for reduction of posterior hip dislocations. J Orthop Trauma. 1999;13:56–7. doi: 10.1097/00005131-199901000-00013, www.ncbi.nlm.nih.gov/pubmed/9892128
3. Bourne RB, Mehin R. The dislocating hip: what to do, what to do. J Arthroplasty. 2004;19(4 Suppl 1):111–4. doi: 10.1016/j.arth.2004.02.016, www.ncbi.nlm.nih.gov/pubmed/15190564