Subluxation and dislocation are frequently cited reasons for THA revision. For patients who cannot accommodate a larger femoral head, an offset liner may enhance stability. However, this change in biomechanics may impact the mechanical performance of the bearing surface. To our knowledge, no studies have compared wear rates of offset and neutral liners. Herein we radiographically compare the in-vivo wear performance of 0mm and 4mm offset acetabular liners. Two cohorts of 40 individuals (0mm, 4mm offset highly crosslinked acetabular liners, respectively) were selected from a single surgeon's consecutive caseload. All patients received the same THA system via the posterior approach. AP radiographs were taken at 6-week (‘pre’) and 5-year (‘post’) postoperative appointments. Patients with poor radiograph quality were excluded (n0mm=5, n4mm=4). Linear and volumetric wear were quantified according to Patent US5610966A. Briefly, images were processed in computer aided design (CAD) software. Differences in vector length between the center of the femoral head and the acetabular cup (pre- and post-vector, Figure 1) allow for calculation of linear wear and wear rate. The angle (β) between the linear wear vector and the cup inclination line was quantified (Figure 1). Patients with negative β were excluded from volumetric analyses (n0mm=11, n4mm=7). Volumetric wear was accordingly calculated accounting for wear vector direction. The results from three randomly selected patients were compared to results achieved using the “Hip Analysis Suite” software package (UChicagoTech).Introduction
Methods
Despite improvements in surgical technique, blood loss continues to be an issue following TJR in 2013. Peri-operative blood loss averages between 1000 and 1500 cc during THR and TKR. Multiple methods have been employed in attempts to minimise this loss. Concepts such as hypotensive anesthesia, tourniquet use, intraoperative blood salvage and autologous pre-donation and postoperative re-infusion drains as well as the use of bipolar sealants, fibrin sprays and thrombin agents have been tried with varying degrees of success. Recently there has been a surge of interest in the use of antifibrinolytics such as Tranexamic Acid (TXA), Aprotinin and Aminocaproic Acid. These medications have a long history of use in other fields such as cardiac and oral surgery but are just recently being utilised following TJR. Of these medications, TXA has been by far the best studied. TXA is a synthetic amino acid that inhibits fibrinolysis by competitively and reversibly blocking the Lysine binding sites on plasminogen. This inhibits its activation and slows the conversion from plasminogen to plasmin and this prohibits the binding of plasmin to fibrin and the subsequent dissolving of clot formation. TXA can be used either topically or intravenously and there are more than 50 clinical papers that have evaluated the effectiveness of TXA in TJR. There is abundant scientific data to support its safety with minimal increased risk of thrombosis and its use should be considered as a safe, effective and economical means of reducing blood loss in TJR in 2013.
There has been a widespread appreciation on the part of both patients and surgeons that pain control following total knee replacement is an important goal. The concepts of both preemptive analgesia and multimodal pain protocols have become increasingly popular. In addition to these ideas, surgeons continue to utilise adjunctive treatments such as peripheral nerve blocks and periarticular injections. Multiple studies demonstrate the efficacy of these therapies. Several authors have published different “cocktails” for their periarticular injections in an attempt to help delineate which components of the cocktail are most important. In addition to deciding on a correct cocktail, how it is delivered is important. This video will demonstrate a technique that increases the likelihood that the injected solution is placed in the appropriate areas and does not simply bath the tissues. Important components of the technique include the use of a small gauge needle (22) and a control syringe to insure proper placement as well as an aim to target the injections into the periosteum of the femur and tibia and the posterior capsule primarily.
