Minimally Invasive Total Knee Arthroplasty

• Osteoarthritis of the knee
• Rheumatoid arthritis of the knee
• Pain that interferes with activities of daily living
• Failure of conservative treatment

• Obesity
• Knee flexion of less than 90 degrees
• Very large bone structure
• Recent or current knee infection
• Systemic infection
• Skin disease overlying the area of the incision
• Extensor mechanism disruption
• Significant quadriceps muscle weakness
• Medical comorbidities that significantly increase the anesthesia risk
• Significant vascular compromise in the surgical leg
• Neuropathic arthropathy

• Leg positioner or two sandbags
• Intraoperative x-ray machine (optional)
• Tourniquet
• Electrocautery
• Rake retractors
• Curved retractors
• Oscillating saw
• Narrow saw blades
• Cement mixer and cement
• Curets
• Minimally invasive total knee arthroplasty set
• Knee arthroplasty components of various sizes
• Small drill
• Pulsatile lavage irrigator
• Drain

• Distal femur
  • Medial condyle: curved to allow rotation during terminal extension
  • Lateral condyle: straighter and has a greater height; can be identified by its terminal sulcus and popliteal groove
• Proximal tibia: medial condyle is more cup-shaped whereas lateral condyle is more flat.
• Patellofemoral articulation: medial and lateral patella facets and trochlear notch of femur
• Static restraints: anterior cruciate ligament, posterior cruciate ligament, medial collateral ligament, lateral collateral ligament ; menisci are secondary restraints.
• Normal tibiofemoral alignment is 5 to 7 degrees.
• The knee is primarily a hinge joint with rolling and gliding occurring during terminal extension.

• Use a compressive dressing.
• Begin DVT prophylaxis immediately after surgery, including both mechanical devices and medication, such as low molecular weight heparin and/or Coumadin.
• Begin range-of-motion exercises with or without use of a CPM machine.
• Begin physical therapy while still in the hospital and continue as an outpatient after discharge.

• Hematoma formation
• Thromboembolism
• Infection
• Patellofemoral complications
  • Instability
  • Extensor mechanism avulsion
  • Quadriceps or patellar tendon rupture
  • Patellar fracture
  • Patellar component loosening
  • Patella clunk syndrome
• Neurovascular complications
• Periprosthetic fracture

Minimally invasive approaches to knee arthroplasty spare the quadriceps muscle and therefore have been associated with increased range of motion, faster mobilization, and decreased pain during the first 4 to 6 weeks after surgery.