CONTRIBUTIONS OF MOVEMENT VARIABILITY TO AVOIDING IMPINGEMENT IN TOTAL HIP REPLACEMENT

Open Access
Author:
Minniti, Melissa Carolyn
Area of Honors:
Kinesiology
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
  • Stephen Piazza , Thesis Supervisor
  • Jessica Schultz, Honors Advisor
Keywords:
  • hip replacement
  • impingement
  • biomechanics
  • movement variability
Abstract:
Following a total hip arthroplasty (THA), certain activities of daily living (ADLs) present challenges to hip mobility which can increase the rate of impingement of the prosthesis and result in decreased range of motion and an increased risk for hip dislocation (Woerner et al., 2017). Activities requiring high amounts of hip flexion, adduction and internal rotation tend to lead to posterior dislocations while activities requiring extension, abduction, and external rotation are more prone to anterior dislocation (Nadzadi et al., 2003). Oftentimes these dislocation events require a surgical revision which presents an increased cost and surgical risk to the patient (Brooks, 2013). Studies have been done evaluating the optimal cup and neck parameters when inserting the prosthesis and have determined a safe zone of anteversion and inclination in which impingement is unlikely (Brooks, 2013; Seagrave et al., 2017; Woerner et al., 2017). Few studies, however, have utilized real subject kinematic data to evaluate these impingement models (Charbonnier et al., 2015; McCarthy et al., 2016; Nadzadi et al., 2003; Pedersen et al., 2005). Furthermore, there is a lack of research evaluating how subject variability in performing impingement-risk ADLs can influence impingement rates and when they occur. This study aims to measure hip motions in healthy elderly subjects and apply these motions to a model to determine the clearances associated with different movement strategies. From there, we aim to associate the different movement patterns used to examine risk of impingement. We measured motions using a six-camera motion system in 10 healthy, elderly subjects who performed a series of 11 different activities using a specifically designed marker set. Of these activities, we focused our analysis on sit-to-stand from a low chair, picking up an object from the floor, and squatting. We then ran the subject motion data through an impingement calculator that used a pre-defined set of implant dimensions to calculate the clearances that occurred in each motion trial. We found that there was a large amount of variability in how subjects performed these movements and that certain strategies maximized clearance which could potentially decrease impingement risk. The most effective strategy was performing activities with low amounts of flexion and high amounts of abduction, which supported one of our hypotheses regarding the effect that different movement strategies would have on clearance. In understanding the potential that movement variability has on minimizing impingement risk, we could provide clinical recommendations for patients undergoing total hip replacement (THR) to maximize the success of the procedure. While this study only examined three motions in 10 healthy subjects, future work would include a full analysis of the other motions measured and aim to collect data on more individuals to determine the consistency of these movement strategies and their effect on clearance and impingement. This would also help elucidate any other trends that may not have been exposed in the three activities measured.