Kinematically aligned TKA restores function by aligning the femoral and tibial components to the normal or prearthritic joint lines of the knee. However, aligning the components to the joint lines of the normal knee also aligns the tibial component in varus, creating concern that varus alignment might result in poor function and early catastrophic failure. We therefore determined whether function and the incidence of catastrophic failure were different when the tibial component, knee, and limb alignment were in a specified normal range, varus outlier, or valgus outlier. We prospectively followed all 198 patients (214 knees) who underwent TKAs between February and October 2008. We treated each knee in this cohort of patients with a kinematically aligned, cruciate-retaining prosthesis implanted using patient-specific guides. From a long-leg scanogram, we measured and categorized alignment of the tibial component as in range (≤ 0°) or a varus outlier (> 0°), alignment of the knee as in range (between −2.5° to −7.4° valgus) or a varus (> −2.5°) or valgus (< −7.4°) outlier, and alignment of the limb as in range (0° ± 3°) or a varus (> 3°) or valgus (< −3°) outlier. We assessed function using the Oxford Knee Score and WOMAC™ score, and reported catastrophic failure as the incidence of revision attributable to loosening, wear, and instability of the femoral or tibial components. The minimum followup was 31 months (mean, 38 months; range, 31–43 months). The mean Oxford Knee Score of 43 and WOMAC™ score of 92 were similar between the three alignment categories. The incidence of catastrophic failure in each alignment category was zero. Kinematically aligned TKA restores function without catastrophic failure regardless of the alignment category. Because 75% of patients had their tibial component categorized as a varus outlier and also had high function and a zero incidence of catastrophic failure, the concern that kinematic alignment compromises function and places the components at a high risk for catastrophic failure is unfounded and should be of interest to surgeons committed to cutting the tibia perpendicular to the mechanical axis of the tibia. Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

The relationship between impingement of the roof of the intercondylar notch on a reconstructed anterior cruciate ligament, and the subsequent stability and range of extension of the joint, was analyzed in forty-seven knees. The extent of the impingement was determined by analysis of the rela

This study compared the stiffness (K), yield load (YL), and slippage (SL) of six tibial fixation methods. These properties were determined from load-to-failure and cyclic tests of double-looped tendon grafts fixed to both animal and young human tissue. Tandem washers (K 259 N/mm, YL 1159 N, SL 0.5 mm) and the Washerloc (K 248 N/mm, YL 905 N, SL 2.0 mm) were the two best fixations. At 500 N of load, which is the estimated daily tension of an anterior cruciate ligament graft during intensive rehabilitation, slippage was significantly greater in either of the other two methods for sutures tied to a post (4.9 mm), double staples (3.3 mm), and a 20-mm spiked metal washer (3.5 mm). Interference screw fixation performed well in animal tissue (YL 776 N), but was significantly worse in young human tissue (YL 350 N), with 57% of the fixations failing before 500 N of load. Animal tissue should not be used to estimate the performance of interference screw fixation in human tissue. Because 57% of the interference screw fixations using human tissue failed at loads below 500 N, their ability to provide adequate fixation during intensive rehabilitation should be questioned. However, both the Washerloc and tandem washers and screws provide fixation structural properties in young human tibia that should be appropriate for intensive rehabilitation.

Orthopedics | The custom-fit approach to total knee arthroplasty in conjunction with removal of osteophytes and preservation of ligaments rapidly returned function; restored motion, stability, and postoperative mechanical axis alignment; effected high patient satisfaction; and had an acceptable clinical outcome. Total knee arthroplasty (TKA) restores a significant degree of function, especially for the

Tension in an anterior cruciate ligament graft is greater with the knee in flexion when the angle of the tibial tunnel in the coronal plane is vertical or more perpendicular to the medial joint line of the tibia; however, the relationship of the angle of the tibial tunnel to knee function has not been studied. Greater graft tension may limit knee flexion or stretch the graft and increase anterior laxity. Five surgeons treated 119 subjects by reconstructing a torn anterior cruciate ligament using a double-looped semitendinosus and gracilis graft and a standardized technique. The femoral tunnel was drilled through the tibial tunnel. Radiographs were analyzed for tibial tunnel placement and a clinical evaluation was made 4 months postoperatively. Knees were assigned to subgroups according to the angle of the tibial tunnel in the coronal plane (65° to 69°, 70° to 74°, 75° to 79°, 80° to 84°, and 85° to 89°), with the angle of the latter subgroup being most vertical. Loss of flexion increased significantly from 0.5° to 6.5° and anterior laxity increased significantly from 0.5 to 2.2 mm as the tunnel angle was increased. The average angle of the tibial tunnel varied significantly, 11° between surgeons (range, 69° to 80°). We found a tibial tunnel angle of 75° or more is associated with greater loss of flexion and anterior laxity. Surgeons do not drill the angle of the tibial tunnel in the coronal plane accurately. We now routinely drill the tibial tunnel at an angle of 65° to 70° in the coronal plane because it may reduce loss of flexion and anterior laxity.