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The Role of Hip Resurfacing. John R. Moreland, M.D. Transforming Orthopaedics: Advanced Outcomes and Techniques January 30-February 2,2008 Vail, Colorado. Déjà Vu . Residency and fellowship at UCLA with Dr. Harlan Amstutz 1973 to 1978 Fellowship with Mr. Michael Freeman in London 1978-79
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The Role of Hip Resurfacing John R. Moreland, M.D. Transforming Orthopaedics: Advanced Outcomes and Techniques January 30-February 2,2008 Vail, Colorado
Déjà Vu • Residency and fellowship at UCLA with Dr. Harlan Amstutz 1973 to 1978 • Fellowship with Mr. Michael Freeman in London 1978-79 • Revised many of my own and other surgeons’ surface failures • Revised only one MOM surface
Is There a Role for Surfaces? • When a stem can not be placed. • How large a role otherwise? • Probably surface replacement should currently have a small roll since for most patients the apparent disadvantages outweigh the advantages. • Time will define the proper role for surface replacement since the experiment to determine its place has already begun.
Difficulty of Surgery • There is general agreement that surface replacement is harder than using stems since the acetabular preparation must be done with the femoral head in place.
Minimally Invasive Issues • Stem placement • Involves less soft tissue damage • Surface placement • Femoral head is in the way and young male patients with big muscles often request surface • Bone conserving • Femoral side: more bone conserving than cemented stems, less so for cementless • Acetabular side: not more bone conserving • Easier to remove for infection or malposition compared to an osseointegrated stem.
Revision for Acetabular Fixation • Stems • Very low, multiple designs • Surface • Low in early reports • Less exposure available to place acetabular component • No adjuvant fixation • Must use cobalt-chrome components • No apical hole • Increased frictional torque
Revision for Femoral Fixation • Stems • Very low, multiple designs • Cementless designs easy to revise if loose. • Surface • Higher rate than stems in early reports • ? Osteonecrosis of femoral head • Small surface area for fixation • Technical insertion issues
Femoral Issues • Stems • Fractures • Operative • Late fractures • Thigh pain • Stress shielding • Surfaces • Neck fractures • Neck narrowing • Stress shielding/osteolysis • ? late neck fractures
Dislocation • Stems • Rates vary • MOM with big heads can be used • Surfaces • Promise of lower rates not realized • Increased soft tissue damage necessary to get exposure is the probable reason
Range of Motion • Stems • Big head diameters relative to neck size give greater ROM before neck impingement • Postoperative ROM actually more dependent on other factors • Surfaces • Poor head to neck diameter ratio • More susceptible to getting heterotopic bone formation and being impaired by it
Nerve Damage • Will probably be higher with surfaces because of the extra retraction necessary to obtain exposure • Some reports have already documented this
Metal on Metal Problems • Metal ion issues • Cancer • Metabolic changes • Fetus exposure • Renal failure • Metal hypersensitivity • Clicking and squeaking
Other Surface Disadvantages • The learning curve for the surgeon, the operating room personnel and the patients • Requires instrument purchases and storage • Requires familiarity with two ways of doing THR • Requires a more expensive prosthesis with insurance coverage issues and possible medical liability issues for a new operation without established indications.
Surface Replacement Advantages • For patients with deformed proximal femurs • Easier to remove than osseointegrated stems for infection or malposition • Easy to market and build your practice • Intuitively attractive • Often confused with MIS and big heads • Do surfaces allow better function? • Might be true for high level activities • Few of my stem patients ever return to distance running • ? Stress fractures of femoral neck
Is There a Role for Surfaces? • Yes: when a stem can not be placed • How large a role otherwise? • Probably a small role since for most patients the disadvantages outweigh the advantages • Long term follow-up will tell us • Need matched series since the differences are apparently not large • Is the function with surfaces better than stems for high level activities?