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 Surfaces Fractures Thigh pain Stress shielding Operative Late fractures Thigh pain Stress shielding Surfaces Neck fractures Neck narrowing Stress shielding/osteolysis ? late neck fractures

Dislocation Stems Surfaces Rates vary MOM with big heads can be used Promise of lower rates not realized Increased soft tissue damage necessary to get exposure is the probable reason

Range of Motion Stems Surfaces 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?

Thank You