Minimally Invasive Total Hip Arthroplasty

• Hip osteoarthritis, primary or secondary
• Rheumatoid arthritis of the hip joint
• Hip osteonecrosis
• Painful arthritis that fails to respond to standard conservative care
• Painful arthritis that significantly affects the patient's activities of daily living (ADLs)

• Obesity (BMI over 30)
• General medical conditions that increase overall anesthesia risk
• History of recent hip infection
• Systemic infection
• Neuropathic arthropathy
• Absent or significantly reduced abductor muscle strength
• Rapidly progressive neurologic disease

• Intraoperative x-ray unit (optional)
• Mini-incision total hip arthroplasty system
• Femoral and acetabular implants of various sizes
• Drill
• Oscillating saw with narrow blade
• Cement and cement mixer (optional)
• Electrocautery unit
• Skin retractors
• Long-arm self-retaining retractor
• Cobra retractors
• Pulsatile lavage irrigator

• The acetabulum: "socket"
  • Anteverted 15 degrees and oriented 45 degrees caudally
  • Thickest at its posterosuperior portion; inferior surface contains the acetabular notch bounded by the transverse acetabular ligament.
• Proximal femur
  • Large spheroidal head
  • Femoral neck is anteverted 14 degrees with a femoral neck-shaft angle of 127 degrees.
• Hip flexors: iliopsoas, rectus femoris, and sartorius muscles
• Hip extension: gluteus maximus and hamstring muscles
• Hip abductors: gluteus medius and gluteus minimus muscles; the adductors include the adductor brevis, adductor longus, adductor magnus, pectineus, and gracilis muscles.
• External rotation: obturator internus, obturator externus, superior and inferior gemellus, quadratus femoris, and the piriformis muscles
• Internal rotation: gluteus medius, gluteus minimus, tensor fascia lata, semimembranosus, semitendinosus, and pectineus muscles

• Use an abduction pillow postoperatively.
• When the patient is alert, bed exercises and limited mobilization may begin on the first postoperative day.
• Begin anticoagulation therapy for thromboembolism prophylaxis per institution protocol.
• Remove the drains after 24 to 48 hours.
• Allow the patient to sit on the side of the bed or in a chair on the first or second postoperative day.
• Begin gait training on the first postoperative day.
• Begin hip extension exercises and discourage the placement of pillows behind the knees. Prone exercises may begin after the first few days.
• Before discharge from the hospital, have the patient work with an occupational therapist on activities of daily living.
• Discharge the patient when he or she can get in and out of bed independently, can walk over level surfaces, and can walk up a few stairs.
• Progress to full weight bearing if 6-week postoperative radiographs show good alignment.
• Continue outpatient physical therapy to allow the patient to regain strength.
• Return to a sedentary job generally is well tolerated at 6 to 8 weeks. Jobs that require lifting and bending may be resumed at 3 months after surgery.
• Obtain routine radiographs at 3 months, 6 months, and 1 year after surgery. Repeat routine radiographs every 1 to 2 years after that.

• Most complications reported are the result of total hip arthroplasty in general and are not directly related to the minimally invasive approach. The primary complication related to the minimally invasive approach is implant malposition because of the limited exposure.
• Infection
• Hematoma formation
• Thromboembolism
• Nerve injuries
• Limb length discrepancy
• Dislocation and subluxation
• Implant malposition
• Implant fracture
• Late complications
  • Mechanical loosening of the implant
  • Heterotopic ossification
  • Particle disease (foreign body reaction to implant debris)

The advantages of minimally invasive hip surgery include shorter operating time (in the hands of an experienced surgeon), less blood loss, better early pain control, and less need for assistive devices. After the first 6 weeks, there appears to be little advantage to the minimally invasive approach except improved cosmesis.