The Incidence of Femoral Component Version Change in Primary Total Hip Arthroplasty with use of the S-ROM Femoral Component.

Kirk Kindsfater
Although use of modular femoral components in revision hip arthroplasty is widely accepted, many still question the need for modular versatility in primary THA. This study of 1000 routine primary THAs implanted with a modular S-ROM femoral component found that nearly half required change in version of the stem to increase stability of the THA construct or to better recreate natural femoral anatomy. Moreover, because no correlations existed, it was difficult to predict the need to alter version based on clinical variables such as gender, age, or diagnosis. This leads to the conclusion that it is advantageous to routinely use a stem that allows variable version as compared to a non-modular stem because is not possible to preoperatively determine when changing version will be required.

Diagnosis of infection in total joint arthroplasty in the early post-op period can be difficult as the post-operative inflammatory response may cloud the clinical picture. Typical laboratory values of inflammatory markers used to help diagnose chronic joint arthroplasty infection are not helpful in the early post-op period as inflammatory markers and synovial fluid WBC can be elevated in the absence of infection. Studies have provided appropriate lab values for the acute post-op situation that are more appropriate and helpful in diagnosing acute post – op arthroplasty infection. The most helpful tests in the acute post-op period are a synovial fluid WBC greater than 10,000. More than 90% polys in the synovial fluid differential and a CRP greater than 100 (normal CRP - 9.0).

Bone loss in revision TKA can be difficult to manage. Fortunately there are a number of “tools” that can be utilized in specific circumstances to make up for bone loss and provide a stable construct. These tools include augments for both the tibial and femoral components, long stems to help offload proximal bony deficits, metaphyseal sleeves that can manage large degrees of bone loss yet provide a stable platform for the prosthesis. Thick tibial trays and distal femoral replacements can handle massive bone loss. Morselized bone or allografts can be utilized to restore bony defects. With these tools bone loss in revision TKA can usually be handled in reliable fashion.

In today’s world of the shrinking health care dollar, operating room and office efficiency are important in helping the surgeon remain productive. Running multiple OR’s concurrently with separate OR crews, separate anesthesia providers and anesthesia providers that have some “skin in the game” are a must for an efficient OR. Utilizing physician extenders in the office setting, particularly when the surgeon is in the operating theatre is also an important way to keep productivity at a maximum.

Bone loss on the femoral side of a total hip arthroplasty is commonly found in failed THA’s or is iatrogenically produced during a revision procedure. Femoral strut grafting and impaction grafting can restore stability and bone loss in specific instances. When bony defects cannot be reconstructed, knowing what type of femoral stem will work – depending on where the stem has bone available to gain fixation – is paramount in providing a stable construct for the patient. Currently, the modular / tapered / fluted stems (Wagner type ) available from many manufacturers have become the workhorse for most revision THA scenarios.