Document Detail

Bony impingement limits design-related increases in hip range of motion.
MedLine Citation:
PMID:  21918798     Owner:  NLM     Status:  MEDLINE    
BACKGROUND: Factors affecting risk for impingement and dislocation can be related to the patient, implant design, or surgeon. While these have been studied independently, the impact of each factor relative to the others is not known.
QUESTIONS/PURPOSES: We determined the effect of three implant design factors, prosthetic placement, and patient anatomy on subject-specific ROM.
METHODS: We virtually implanted hip geometry obtained from 16 CT scans using computer models of hip components with differences in head size, neck diameter, and neck-shaft angle. A contact detection model computed ROM before prosthetic or bony impingement. We correlated anatomic measurements from pelvic radiographs with ROM.
RESULTS: When we implanted the components for best fit to the subject's anatomy or in the recommended orientation of 45° abduction and 20° anteversion, ROM was greater than 110° of flexion, 30° of extension, 45° of adduction-abduction, and 40° of external rotation. Changes in head size, neck diameter, and neck-shaft angle generated small gains (3.6°-6°) in ROM when analyzed individually, but collectively, we noted a more substantial increase (10°-17°). Radiographic measurements correlated only moderately with hip flexion and abduction.
CONCLUSIONS: It is feasible to tailor implant placement to each patient to maximize bony coverage without compromising ROM. Once bony impingement becomes the restricting factor, further changes in implant design may not improve ROM. Radiographic measurements do not appear to have value in predicting ROM.
Adam Bunn; Clifford W Colwell; Darryl D D'Lima
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Clinical orthopaedics and related research     Volume:  470     ISSN:  1528-1132     ISO Abbreviation:  Clin. Orthop. Relat. Res.     Publication Date:  2012 Feb 
Date Detail:
Created Date:  2012-01-11     Completed Date:  2012-02-27     Revised Date:  2013-06-27    
Medline Journal Info:
Nlm Unique ID:  0075674     Medline TA:  Clin Orthop Relat Res     Country:  United States    
Other Details:
Languages:  eng     Pagination:  418-27     Citation Subset:  AIM; IM    
Shiley Center for Orthopaedic Research and Education at Scripps Clinic, 11025 North Torrey Pines Road, Suite 200, La Jolla, CA 92037, USA.
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MeSH Terms
Analysis of Variance
Arthroplasty, Replacement, Hip / adverse effects,  instrumentation*
Computer Simulation
Computer-Aided Design
Hip Joint / physiopathology,  radiography,  surgery*
Hip Prosthesis*
Models, Cardiovascular
Prosthesis Design
Range of Motion, Articular
Recovery of Function
Time Factors
Tomography, X-Ray Computed
Treatment Outcome

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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