Background Traditionally, the placement of the tibial component in total knee arthroplasty (TKA) has focused on maximizing coverage of the tibial surface. However, the degree to which maximal coverage affects correct rotational placement of symmetric and asymmetric tibial components has not been well defined and might represent an implant design issue worthy of further inquiry. Questions/purposes Using four commercially available tibial components (two symmetric, two asymmetric), we sought to determine (1) the overall amount of malrotation that would occur if components were placed for maximal tibial coverage; and (2) whether the asymmetric designs would result in less malrotation than the symmetric designs when placed for maximal coverage in a computer model using CT reconstructions. Methods CT reconstructions of 30 tibial specimens were used to generate three-dimensional tibia reconstructions with attention to the tibial anatomic axis, the tibial tubercle, and the resected tibial surface. Using strict criteria, four commercially available tibial designs (two symmetric, two asymmetric) were placed on the resected tibial surface. The resulting component rotation was examined. Results Among all four designs, 70% of all tibial components placed in orientation maximizing fit to resection surface were internally malrotated (average 9°). The asymmetric designs had fewer cases of malrotation (28% and 52% for the two asymmetric designs, 100% and 96% for the two symmetric designs; p \ 0.001) and less malrotation on average (2°and 5°for the asymmetric designs, 14°for both symmetric designs; p \ 0.001). Conclusions Maximizing tibial coverage resulted in implant malrotation in a large percentage of cases. Given similar amounts of tibial coverage, correct rotational positioning was more likely to occur with the asymmetric designs. Clinical Relevance Malrotation of components is an important cause of failure in TKA. Priority should be given to correct tibial rotational positioning. This study suggested that it is easier to balance rotation and coverage with asymmetric tibial baseplates; clinical research will need to determine whether the observed difference affects patellar tracking, loosening rates, or the likelihood of revisions after TKA.

Long-term alendronate treatment did not appear to cause thickened femoral cortices within the detection limits of our method. This finding contrasts with the notion that long-term alendronate treatment leads to generalized cortical thickening.

Interdisciplinary rating agreement of AC joint injuries is low. Further study may help improve education and communication about AC joint injuries among physicians.

Correction of proximal tibia varus deformity has been used with success. Our Protocol is to use monolateral frame to correct varus of less than 10 degrees and to use the Taylor spatial frame for deformities greater than 10 degrees and for multiplanar deformities. Is this protocol successful? Ninety-one limbs in 68 patients with proximal tibia varus were treated with percutaneous proximal tibial osteotomy and external fixation. The monolateral and spatial frames were used for 36 and 55 limbs, respectively. Each group was further subdivided into neutral or intentionally overcorrected subgroups. Monolateral group time of correction and time in frame was 15 days (8 to 20) and 101 days (81 to 133), respectively. The preoperative mechanical axis deviation (MAD) was 22 mm medial (10 to 44). Postoperative MAD in the neutral subgroup was 5 mm lateral (2 to 10) and 3 mm medial (0 to 7). Postoperative MAD in the overcorrected subgroup was 10 mm lateral (4 to 20) and one patient was 5 mm medial. Medial proximal tibial angle (MPTA) improved from 85 degrees (79 to 89) to 90 degrees (85 to 96) in the neutral group and to 92 degrees (85 to 98) in the overcorrected group. Spatial frame group time of correction and time in frame was 34 days (7 to 99) and 130 days (95 to 177), respectively. The preoperative MAD was 40 mm medial (range 5 to 155). This improved to 5 mm medial (0 to 30) and 4 mm lateral (0 to 7) in the neutral group, and 17 mm medial (0 to 35) and 11 mm lateral (4 to 28) in the overcorrection group. MPTA improved from 80 degrees (40 to 87) to 88 degrees (83 to 96) in the neutral group and to 84 degrees (89 to 97) in the overcorrected group. In both groups, there was no significant change in the ankle or knee range of motion. There was one refracture in both groups. Our algorithm for treating proximal tibial varus deformities is safe and effective. For simple varus deformities, we recommend use of the monolateral frame. We reserve the use of the spatial frame for large or complex deformity correction.

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