Effect of a distal centralizer on the positioning of an anatomical stem.

Femoral stem centralizers were originally designed for double tapered, straight stems. In a slightly modified configuration, the PMMA centralizer is plugged in a hole in the tip of the ABG II femoral prosthesis. The purpose of this study was to determine the effect of the centralizer on the position of the anatomical ABG II stem. Thirty-nine cemented ABG II stems with a centralizer were compared with thirty-nine stems without a centralizer. We evaluated positioning of the tip of the stem according to a standard selection of criteria, using conventional AP and lateral X-ray imaging. The centralizer supplied with the ABG II was found to have no additional value in guaranteeing optimal varus-valgus positioning. If a stem was not placed neutral, generally it was placed in a slight valgus position. The number of deficient cement mantles was not influenced by the three-fin centralizer. Furthermore, the distal centralizer of the ABG II prosthesis adds a length of 27 mm to the stem, and the distal cement plug found in stems with centralizer was almost twice as long on average. The ABG II centralizer was found in this study to provide insufficient guiding of this anatomical stem and to add excessive length to the distal cement plug.

The use of autologous blood to improve exercise capacity after total hip arthroplasty: a preliminary report.

BACKGROUND: Venesection of red blood cells in healthy well-trained subjects decreased the maximum oxygen uptake parallel with the reduction in hemoglobin (Hb) level. Based on the large Hb decrease that is seen after total joint surgery, one could expect a decrease in performance as well. The purpose of this study was to investigate whether autologous blood enhanced performance on a bicycle ergometer in patients after total hip arthroplasty. STUDY DESIGN AND METHODS: Nine patients scheduled for elective total hip arthroplasty in an accelerated stay program participated in a preoperative autologous blood donation (PABD) program. Weeks before the scheduled surgery, patients donated 4 units of blood and received standard erythropoietin treatment. Physical fitness was assessed during exercise test on a bicycle ergometer. Each patient was matched with three previously tested patients. RESULTS: Patients in both groups were 69.0 years old (range, 66-74 years vs. 61-77 years). None of the patients had relevant cardiovascular abnormalities. On average patients received 3.3 units of blood because 3 units were not transfused. The PABD group showed a Hb decrease of 0.5 g per dL (4%) on the fourth postoperative day versus 4.4 g per dL (31%) in the control group. The decline in power output on Day 4 was significantly less in the PABD group compared with the control group (t test, p = 0.026). CONCLUSION: From this pilot study it can be concluded that correction of the postoperative Hb decrease was associated with a lower decrease in maximum power output, compared to the control group. On Days 23 and 39, however, the difference in performance between the PABD group and control group had disappeared.