1	Modularity in Primary Total Hip Arthroplasty Paul J. Duwelius, M.D. AAHKS Annual Meeting Gaylord Resort Dallas, Texas 11/2/07
2	Purpose Justification for modularity Historical perspective Review anatomical variability Surgical technique Illustrate clinical examples
3	Primary THR Concerns Leg length Offset Dislocation Anatomical Variation
4	Anatomical Issues in THA Females have shorter head heights and shorter offsets No correlation between head height and offset (Saguno, Noble, et al) Females have higher total anteversion (Dorr)
5	History of Modularity in U.S. Early 1980’s (Auto-Phorr) Mid 1980’s (S-ROM) 1994 (Cremascoli)
6	Track Record Clinically proven tapered wedge Slim A/P dimension TivaniumÒ Ti-6Al-4V Alloy Circumferential plasma spray Minimized lateral shoulder
7	Upside of Modular Necks Independent version Independent offset Independent length
8	Independent Leg Length, Offset and Version Control
9	Upside of Modularity Length dictated by neck module 0 femoral heads only No skirted heads
10	So What? Improved motion Decreased impingement Decreased dislocation Restores normal kinematics
11	Clinical Issues Initial Stability Tapered wedge Wide M/L and slim A/P dimension
12	Intraoperative Options Leg length adjustment Independent adjustment without affecting offset Broad range of head centers using grid Low head center options preserve bone
13	Clinical Issues Range of motion Reduced neck geometry with use of +0 heads only Necks with version
14	Facilitates MIS Surgery Easier stem insertion Intraoperative options Less soft tissue trauma
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19	Anatomical Findings Women tend to show shorter femoral offset than men. Women tend to demonstrate greater anteversion than men.1-3 Women have smaller acetabulum which may preclude the use of larger femoral ball heads in the reconstruction.
20	Clinical Findings Suggested combined femoral and acetabular anterversion of approximately 10° greater for female patients.1 Dislocation is up to 4x as prevalent in women than men.2-4 Component positioning and knowledge of femoral and acetabular anteversion are very important factors in the risk of impingement and dislocation.2
21	Enhanced Range of Motion Enhanced range of motion mitigates risk of impingement which is a source of third body wear debris and dislocation Dislocation is the second most prevalent complication in total hip replacement with a 2-4% incidence Dislocation is a $75 million annual financial burden to the U.S. health care system.
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23	Summary Anatomic & gender differences exist Impingement & dislocation are problems Restore normal kinematics Modularity addresses these issues
24	Thank You!