Rahul Deshmukh, MD

Thomas Thornhill, MD

Dr. Deshmukh retrospectively reviewed a series of 2000 consecutive patients to assess the incidence in which modular tibial inserts are advantageous to the patient. In this series of patients who all underwent a PCL-retaining total knee arthroplasty, insert exchanges were used in approximately 2% of cases with an average follow up of 8 years. Indications for exchange included polyethylene wear and instability, with a few performed incidentally. Of the patients who underwent an exchange for polyethylene wear there was a 100% survival at follow-up. Dr. Deshmukh concluded that modularity appears to have a significant benefit during re-operation with PCL retaining knee system.

Dr. Thomas Thornhill first commended Dr. Deshmukh on a wellorganized presentation. He wondered if use of a cross- linked polyethylene would have any affect on the rates of wear seen in this patient population. Dr. Deshmukh and Scott responded to this comment by saying that surgeons should be cautious about the use of cross-linked polyethylene in knees. The articulation and the forces around the knee are very different from that in the hip. More studies are needed to prove its benefit in total knee arthroplasty.

David L. Scott, MD

Henry J. Mankin, MD

Dr. Scott talked about the numerous steps involved in the production of a new drug, including issues pertaining to mapping the target receptor. More specifically, Dr. Scott focused on integrins, heterodimeric receptors that mediate cell-cell and cell-matrix interactions. For example, integrins which mediate platelet activation and thrombosis have been targeted in the prevention and treatment of ischemic cardiac disease. Reopro, one such drug, has been shown to reduce the 30-day incidence of myocardial infarction and death in patients with unstable angina. Within the field of orthopaedic surgery, Dr. Scott addressed the treatment of Gaucher’s disease, which is caused by a mutation in the gene encoding the glucocerebrocidase enzyme. Indeed, recombinant glucocerebrocidase can reduce the pathologic accumulation of intracellular lipids, thus leading to relief of symptoms.

Dr. Mankin commended Dr. Scott on his magnificent effort and superb science leading to this work. Dr. Mankin further informed the audience that integrin is a relatively new term. His research revealed that the term didn’t actually exist before 1992 in many textbooks. Finally, he commented on the fascinating structure of the integrin and the unique nature in which it gains entry into the cell.

David Kim, MD

Thomas Gill, MD

Dr. David Kim presented a biomechanical study on the effects of twisting and braiding on the tensile properties of four strand human hamstring tendon grafts used for ACL reconstruction. In this study, Dr. Kim tested gracilis and semitendinosus free tendon grafts harvested from unembalmed human cadaveric knees. Doubled gracilis and semitendinosus (DGST) grafts were either twisted or braided. The contralateral DGST grafts were tested in parallel in the control group. Dr. Kim found that twisted and braided DGST grafts had reduced failure load and stiffness as compared to parallel controls. Based on the results of this study, Dr. Kim cautions against the use of twisted or braided tendon grafts in anterior cruciate ligament replacement surgery.

Dr. Gill commended Dr. Kim on challenging accepted principles with his research. He went on to comment that graft stiffness may not necessarily correlate with better clinical outcomes, as in vitro data is difficult to extrapolate to in vivo results. He further went on to wonder how the graft fixation in this study compared to the graft fixation in the operating room.

Arun Ramappa, MD

Arthur Boland, MD

Patellofemoral malalignment, which can cause anterior knee pain, is often unresponsive to conservative therapy. Two of the surgical techniques used to treat patellofemoral malalignment, the Elmslie-Trillat and Fulkerson procedures, are based upon tibial tubercle osteotomy and/or transfer. In this cadaveric study, Dr. Ramappa compared medialization of the tibial tubercle (Elmslie-Trillat procedure) to anteromedial tubercle transfer (Fulkerson procedure) in their effects on patellofemoral tracking and patellofemoral contact stresses. Dr. Ramappa found lower contact stresses across the patellofemoral articulation with medialization, and thus recommended that medialization be the realignment procedure of choice in appropriate patient with patellofemoral pain.

Dr. Boland praised Dr. Ramappa for his experimental design and methods. He noted that neither procedure increased the patellofemoral contact area. He suggested that future investigations should take into account patellar tilt secondary to tight lateral structures as well as malalignment in the coronal plane.