Closed reduction of constrained total hip arthroplasty

Area of Science:

• Orthopedic Surgery
• Biomedical Engineering
• Materials Science

Background:

• Constrained polyethylene liners are used in total hip arthroplasty to prevent dislocation.
• Dislocation remains a risk (4-29%) even with constrained components, often necessitating open reduction.
• The impact of closed reduction on the integrity of constrained liners is not well understood.

Purpose of the Study:

• To evaluate the effect of closed reduction on the polyethylene constraint mechanism in total hip arthroplasty.
• To assess whether closed reduction predisposes patients to further dislocations.
• To report a technique and clinical outcomes for closed reduction of constrained total hip arthroplasty.

Main Methods:

• In vitro simulation of hip dislocation and closed reduction of acetabular components with constrained polyethylene liners.
• Testing of the polyethylene constraint mechanism's strength after simulated dislocation and reduction.
• Clinical case series of patients undergoing closed reduction for dislocated constrained total hip arthroplasty.

Main Results:

• After simulated dislocation and closed reduction, 76% of the capture mechanism strength was retained.
• No additional damage to the polyethylene liner was observed after the simulated procedures.
• Six patients underwent successful closed reduction and remained stable without further dislocations for 7-72 months.

Conclusions:

• Closed reduction of Poly-Dial constrained polyethylene liners can be a viable and safe option.
• This technique appears to maintain the integrity of the constraint mechanism.
• Closed reduction may successfully manage dislocations without increasing the risk of subsequent instability.