Knee and ankle joint laxities are greater for women compared to men; however, the cyclic estradiol and progesterone fluctuations that occur during the menstrual cycle do not produce cyclic fluctuations of joint laxity. Studies using joint laxity to identify a subject at risk for ligamentous injury need only consider making measurements at a specific point in time, such as during a preseason screening evaluation.

Tibial tunnel variations are not solely dependent on the location of guide pin placement. There may be signifi cant changes in intra-articular tunnel position and dimensions based on the drilling angle despite ideal pin position. Using a simple mathematical model, this effect was quantifi ed and its clinical implications are discussed. [J Knee Surg. 2007;20:289-291.]

Stable graft fixation is critical to successful ACL reconstruction. Graft migration must be prevented during the 6 to 12-week postoperative period that is required for graft-tunnel incorporation. Maximizing interference screw fixation, avoiding pitfalls of screw insertion, managing graft-tunnel mismatch, and alternative fixation techniques are discussed. Key Words: Anterior cruciate ligament-GraftFixation.Contemporary rehabilitation protocols after anterior cruciate ligament (ACL) reconstruction stress early postoperative knee motion and weight bearing to reduce morbidity secondary to stiffness, delayed strength recovery, and anterior knee pain. In the first weeks after surgery the weakest link of the reconstructed ACL is not the graft itself but rather the fixation sites. Resultant graft forces during an accelerated rehabilitation protocol are estimated to range between 150 N and 450 N. 24,28,51,52,61,68 Therefore, the stability of initial graft fixation is critical and must be strong enough to withstand these forces and prevent graft migration during the six to twelve week period that is required for graft-tunnel incorporation. 16,44,50,67 Patellar tendon allograft incorporation may be delayed compared with autografts, 37 and when this graft is used fixation may need to provide additional primary stability beyond 12 weeks.It has been estimated that ACL graft failure is responsible for 0.7% to 8% of cases of recurrent instability after reconstruction. Furthermore, errors in surgical technique are the primary cause of early graft failure. 29,32,34 In addition to inadequate primary fixation, technical factors which should be considered include nonanatomic tunnel placement, graft impingement from an inadequate notchplasty, improper graft tensioning, graft material problems and failure to address injured secondary stabilizers.In the absence of these problems early construct failures are almost universally related to loss of fixation.The purpose of this manuscript is to discuss interference screw fixation with a focus on avoiding pitfalls of insertion, strategies for managing graft-tunnel mismatch, and graft fixation alternatives which may be required in primary or revision situations. INTERFERENCE SCREW FIXATIONIn 1983 Lambert 46 introduced interference fixation using 6.5 mm AO cancellous metal screws (Synthes, Paoli, PA). In the landmark human cadaveric study by Kurosaka et al.,44 novel headless fully threaded 9-mm interference screws demonstrated superior fixation strength compared with 6.5 mm AO cancellous screws, sutures over buttons, and staples. The maximal load to failure was 436 Ϯ 90 N. Other authors have subsequently shown that the single load to failure strength of metal interference screws with human in vitro models is up to 703 N. 14,41,54,75 Despite the fact that specimen donors in these studies were on average older with decreased bone density compared with the ACL reconstruction patient population, fixation strength was adequate for accelerated rehabilitation.Multiple factors are related to the ultima...

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Summary: Macrotraumatic extensor mechanism complications do occur after central third patellar tendon harvest for anterior cruciate ligament (ACL) reconstruction and include intra-or postoperative patella fracture and patellar tendon rupture. These are significant complications that often require additional surgery. Intraoperative precision when harvesting the patellar tendon, bone grafting the donor sites and implementing contemporary postoperative rehabilitation and bracing protocols may minimize their occurrence.