Abstract
Purpose
Change of the pelvic tilt is an important factor affecting walking after total hip arthroplasty (THA). There are many reports of static evaluation of pelvic tilt by X-ray, however, there are few reports of dynamic evaluation during walking. In this study, we investigated change of pelvic tilt of THA subjects before and after operation during walking using an optical position sensor.
Subjects and Methods
5 normal volunteers (mean age 26.6 years old, Control group) and 10 patients who underwent primary THA due to unilateral osteoarthritis of the hip (mean age 61 years old, THA group) were enrolled. We have measured angle of the hip and inclination of the pelvis in the mid-stance phase of the affected limb during walking using a motion analyzer (MAC3D system) and acquired physical assessment of the hip preoperatively, 3 weeks postoperatively and 3 months postoperatively. The acquired data of inclination of the pelvis was classified as Duchenne or Trendelenburg type compared with that of normal volunteers.
Result
Trendelenburg type in 6 patients and Duchenne type in 4 patients were found preoperatively with THA group. Trendelenburg type showed abductor muscle weakness and limited range of motion (ROM) in hip abduction, and Duchenne type showed a limited ROM in hip adduction with physical examination. At 3 weeks after surgery, 9 of 10 THA patients resulted in the Duchenne type. At 3 months after surgery, the inclination angle of the pelvis showed the same as that of healthy subjects in 5 of the 9 patients, in which hip abduction ROM increased and abductor muscle strength recovered among Trendelenburg type and hip adduction ROM increased among Duchenne type (Figure 1). The pelvic inclination returned to preoperative state in 4 patients, in which limitation of hip abduction ROM and abductor muscle weakness remained in Trendelenburg type preoperatively and limitation of hip adduction ROM remained in Duchenne type preoperatively (Figure 2).
Discussion
As a risk factor for limping after THA, preoperative limitation of ROM in hip abduction or adduction can be related, leading to necessity of systematical estimation for ROM of the hip with physical assessment and pelvic tilt type in the mid-stance during walking prior to surgery. In addition, preoperative maximum hip adduction angle and abduction muscle strength can be affected to change of the pelvic tilt after THA. It is important to recover of these ROM and muscle strength with physical therapy for prevention of postoperative limping.
