The purpose of this study was to measure the effects of variation in placement of the femoral tunnel upon knee laxity, graft pretension required to restore normal anterior-posterior (AP) laxity and graft forces following anterior cruciate ligament (ACL) reconstruction. Two variants in tunnel position were studied: (1) AP position along the medial border of the lateral femoral condyle (at a standard 1 1 o'clock notch orientation) and (2) orientation along the arc of the femoral notch (o'clock position) at a fixed distance of 6--7 mm anterior to the posterior wall. AP laxity and forces in the native ACL were measured in fresh frozen cadaveric knee specimens during passive knee flexion-extension under the following modes of tibial loading: no external tibial force, anterior tibial force, varus--valgus moment, and internal-external tibial torque. One group (15 specimens) was used to determine effects of AP tunnel placement, while a second group (14 specimens) was used to study variations in o'clock position of the femoral tunnel within the femoral notch. A bone-patellar tendon-bone graft was placed into a femoral tunnel centered at a point 6-7 nim anterior to the posterior wall at the 11 o'clock position in the femoral notch. A graft pretension was determined such that AP laxity of the knee at 30 deg of flexion was restored to within 1 mm of normal; this was termed the laxity match pretension. All tests were repeated with a graft in the standard 1 I o'clock tunnel, and then with a graft in tunnels placed at other selected positions. Varying placement of the femoral tunnel 1 h clockwise or counterclockwise from the 1 I o'clock position did not significantly affect any biomechanical parameter measured in this study, nor did placing the graft 2.5 mm posteriorly within the standard l l o'clock femoral tunnel. Placing the graft in a tunnel 5.0 mm anterior to the standard 1 1 o'clock tunnel increased the mean laxity match pretension by 16.8 N (62%) and produced a knee which was on average 1.7 mm more lax than normal at 10 deg of flexion and 4.2 mm less lax at 90 deg. During passive knee flexion-extension testing, mean graft forces with the 5.0 mm anterior tunnel were significantly higher than corresponding means with the standard 11 o'clock tunnel between 40 and 90 deg of flexion for all modes of constant tibial loading. These results indicate that AP positioning of the femoral tunnel at the 1 1 o'clock position is more critical than o'clock positioning in terms of restoring normal levels of graft force and knee laxity profiles at the time of ACL reconstruction.

Notchplasty is frequently performed in conjunction with anterior cruciate ligament reconstruction. Bench loading tests were performed on 26 fresh-frozen knee specimens to measure excursion of a bone-patellar tendon-bone graft, anterior-posterior laxity of the knee, and graft forces before and after performing a 2-mm and a 4-mm notchplasty. The mean intraarticular pretension required to restore normal anterior-posterior laxity at 30 degrees of flexion (laxity-matched pretension level) was 27 N before notchplasty, 48 N after 2-mm notchplasty, and 65 N after 4-mm notchplasty. The mean graft pretension decreased 53% and 58%, respectively, on completion of a loading test series involving anterior-posterior and constant tibial loading forces. Mean laxity increased 1.4 mm at full extension and decreased 1.8 mm at 90 degrees of flexion after a 2-mm notchplasty. Mean graft forces increased markedly between 30 degrees and 90 degrees of passive flexion after notchplasty. Our results show that after a notchplasty, a higher level of graft pretension will be necessary to restore normal laxity at 30 degrees of flexion. This increased level of pretension, combined with changes in graft excursion, produced dramatic increases in graft force when the knee was flexed to 90 degrees. These relatively high forces would be detrimental to a remodeling graft and could lead to subsequent failure of the reconstruction.

Study Design. A retrospective study.Objective. To determine the efficacy of using intraoperative cell saver in decreasing the need for blood transfusion.Summary of Background Data. Lumbar spine surgery is associated with potential large intraoperative blood loss, which may put patients at risk for blood transfusions. Preoperative autologous blood donation mitigates the need for allogenic blood transfusion, but does not eliminate it. Cell-saver use has been advocated to further reduce the need for transfusion, but recent reports have called its efficacy into question.Methods. Data were collected from 188 patients undergoing consecutive instrumented lumbar laminectomy and fusion. One hundred and forty-one of these patients had cell saver used during their procedures, whereas 47 did not. In addition, previously published data from similarly treated patients were used for analysis. Operative blood loss, autologous and allogenic blood transfusions, discharge hematocrit, and patient factors were analyzed.Results. A significant increase in the number of blood transfusions was found in the cell-saver group. The cellsaver group also had a significantly increased blood loss compared with the non-cell-saver group. Using analysis of covariance, we determined the effect of blood loss on the need for transfusion. The results showed that correcting for blood loss eliminated the significance in the transfusion difference, but cell saver still was not able to decrease the transfusion need. Comparing our current results with our previously published results also demonstrated no benefit of cell saver use.Conclusion. Use of cell saver in instrumented lumbar fusion cases was not able to decrease the need for blood transfusion. Cell-saver use was associated with a significantly higher blood loss.

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