Intraoperative acetabular fracture and pelvic discontinuity in THR – Leave it or Treat it

• Periprosthetic acetabular fracture rare complication.

• Increasing incidence with uncemented cups

Periprosthetic Acetabular fracture

• Intraop. fracture with comp. Insertion

• Intraop. fracture with comp. Removal

• Traumatic Fracture

• Spontaneous Fracture

• Pelvic discontinuity

Intraop Periprosth. Acetabular fracture with Component insertion

• Exact prevalance unknown

• Depends on – a) Surgical tech. used for comp. stability b) Quality of host bone

Surgical technique used for component stability

• Line to line reaming - - size of comp. same as last reamer diameter - adjunctive screw used for fixation

Disdavantage of screw fixation Neurovascular inj fretting & corrosion wear & osteolysis

Surgical technique used for component stability

• Under Reaming of Acetabulum Reamer 1-2 size smaller than component Stability without adjunctive screws

Incidence of intraop. fracture

Intraop Periprosth. Acetabular fracture Cadaver studies

• Kim et al

• Increased incidence with comp oversized by 2-4 mm

• Smaller sized acetabulum – higher chance of intraop fracture

• Large size acetabulum – rim fracture• Small size acetabulum - coloumn fracture

Intraop Periprosth. Acetabular fracture Experimental studies

• Ries et al

Small sized acetabulum underream by 1 Large sized acetabulum undreream by 3

• Series of 13 periprosthetic acetabular fracture

• 11 occurred in women above 60 with Rh. Arth.

• Quality of host bone important factor

• 4 fracture diagnosed pot op – 2 reqd revision and I case component migrated substantially

Tips to avoid Intraop Periprosth. Acetabular fracture

• Careful reaming avoiding violation of ant., post. Or medial wall.

• Failure of component to advance with progressive blows – additional reaming.

• Avoid underreaming > 2mm• Osteopenic bone – minimal underreaming /line

to line contact• Avoid overreaming around dome of prosthesis –

leads to fracture

Pelvic Discontinuity

• Separation of sup. portion of acetabulum from inf. portion

• Usually seen in cases of revision THR

Pelvic Discontinuity

• Radiological indicator - Transverse fracture line - Medial translation of inf. portion of

hemipelvis - break in ilioischial line - Rotation of inf hemipelvis - asymmetric obturator rings

Classification system

Intraop Periprosth. Acetabular fracture

• Recognize fracture occurred

• Assess – displaced / undisplaced

• Stability of implant

• X_ ray – Obturator and Iliac views

Intraop. Management

• Type IA

• Fracture involves the wall in Type IA

• Fracture undisplaced and component stable - Leave the component in place - Use adjunctive screws

Intraop. Management• Type IB - Fracture involving Column - Implant Unstable

• Remove component & Reduce fracture – internal fixation with plate and screws

• Line to line reaming • Implant Multihole acetabular cup

• Post op IA & IB – Toe touch weight bearing 6 – 12 weeks

Intraop. Management

• Type IC• Fracture not recognised intraoperatively

• Component migration postoperatively• Failure

Intraop. Management

• Type IC

• Trial of extended toe touch weight bearing• Early acetabular revision after discussion with pt.

• Failure rate Component fixed without screws Involvement of column Fracture displaced

Intraop. Management

• Pelvic Discontinuity• < 50% bone loss - Hemispherical porous coated acetabular cup - Posterior plate and screws - Morcellized bone graft at site of discontinuity

• > 50% bone loss – Acetabular reconstruction cage

Periprosth. Acetabular fracture Treatment Algorithm

Periprosth. Acetabular fracture Treatment Algorithm

Summarize

• Intraop periprosthetic acetbular frature complex injuries

• Implant should be stable

• Rigid fixation of fracture & bone grafting

• Assess remaining host bone

• Loss > 50% bone – Acetabular cage from ilium to ischium