Total Hip Arthroplasty
Mech 410/550 H Surgical Procedure Presentation
Clinical Application
Approximately 144 000 total hip arthroplasties were performed in 1997 Main cause is osteoarthritis (70%) Patient indications are pain and reduced range of motion
Additional Causes
Rheumatoid arthritis Trauma and post-traumatic arthritis Congenital deformities Benign and malignant tumors/lesions Avascular necrosis
Anatomy
Ref: http://www.tcd.ie/bioengineering/prosthetic_implants%20.htm
Procedure
Ref: ©MMG 1999 http://orthopedics.about.com/gi/dynamic/offsite.htm?site=http%3A%2F%2Fwww.medicalmultimediagroup.com%2F pated%2Fjoints%2Fhip%2Fhip_replacement.html
Cemented or Cementless
See Reference Section
Step 1: Incision
Minimal is preferred Removal of osteophytes Avoid transverse acetabular ligament
Ref: Desert Orthopaedic Center http://www.desertorthopedic.com/mini.asp
Ref: http://www.bonecement.com/application/totalhip.html
Step 2: Removal of Femoral Head
Femoral head dislocated Femoral head removed at neck
See Reference Section
Step 3: Prepare Acetabulum
Drill and reamer used to remove cartilage and create cup shape Anchorage holes made (cemented case) Remove debris with brush
See Reference Section
Step 4: Insertion of Acetabular Component
Held in place by friction, screws or cement Pressurization carried out in cemented case
See Reference Section
Step 5: Preparation of Femoral Canal
Straight reamer creates hole Remove debris Insert distal plug
See Reference Section
Step 6: Insertion of Femoral Stem
Friction fit or cement If cement used pressurize cement to create an even cement mantle
See Reference Section
Step 7: Attachment of Femoral Head
Attach femoral head to stem (by Morse taper)
See Reference Section
Step 8: Insertion of Head into Acetabular Component
Femoral head is located into acetabular liner Range of motion is verified
See Reference Section
Intraoperative Problems
Nerve injury Vascular injury Thrombophlebitis Cement reaction/fat embolus Fracture/canal perforation
Postoperative Problems
Loosening (72.3% of hip revisions are due to loosening of the femoral component) Dislocation Infection Wear – systemic effects Alignment Subsidence Fracture 12-15 year average implant life
Difficult Steps
Introduction and alignment of acetabular cup Protection of UHMWPE acetabular cup Sufficient reaming of femoral canal Creating even cement mantle
Possible Image-Guided or Robotic Applications
Sizing the acetabular space Acetabular component positioning Femoral reaming (size and position of canal) Maintaining acetabular and femoral components during polymerization of PMMA (if cement is used) All positions can be verified using imageguidance (usually fluoroscopy)
Existing Image-Guided and Robotic Approaches
Anterior approach minimally invasive technique using fluoroscopy Robodoc – robotic reaming method
References
All ©MMG 1999 were found at: http://orthopedics.about.com/gi/dynamic/off site.htm?site=http%3A%2F%2Fwww.med icalmultimediagroup.com%2Fpated%2Fjoi nts%2Fhip%2Fhip_replacement.html
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