Muscle damage during MIS total hip arthroplasty: Smith-Petersen versus posterior approach.

Decreased muscle damage is a reported benefit of minimally invasive surgical (MIS) approaches in total hip arthroplasty (THA). We compared the extent and location of muscle damage during THA using the MIS anterior Smith-Petersen and MIS posterior surgical approaches. THA was performed in six human cadavers (12 hips). One hip was assigned to the Smith-Petersen approach and the contralateral hip to the posterior approach. Muscle damage was graded with a technique of visual inspection to calculate a proportion of surface area damage. Less damage occurred in the gluteus minimus muscles and minimus tendon with the Smith-Petersen approach. A mean of 8% of the minimus muscle was damaged via the Smith-Petersen approach, compared to 18% via the posterior approach. The tensor fascia latae muscle was damaged (mean of 31%), as well as direct head of the rectus femoris (mean 12%) during the Smith-Petersen approach. The piriformis or conjoined tendon was transected in 50% of the anterior approaches to mobilize the femur. The posterior approach involved intentional detachment of the piriformis and conjoined tendon and measurable damage to the abductor muscles and gluteus minimus tendon in each specimen. Clinical outcome studies and gait analysis are necessary to ascertain the functional implications of these findings.