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Although kinematically aligned TKA has a high proportion of varus or valgus outliers using mechanically aligned criteria, the intra-operative forces in the medial and lateral compartments of patients with outlier alignment were comparable with those with in-range alignment, with no evidence of overload of the medial or lateral compartment of the knee. Cite this article: 2017;99-B:1319-28.

The incidence of tibial component failure after KA TKA was 0.3% and was caused by posterior subsidence or posterior edge wear and not varus subsidence. The strategy for lowering the risk of tibial component failure when performing KA is to set the tibial component parallel to the flexion-extension plane (slope) and varus-valgus plane of the native joint line.

Minimizing flexion of the femoral component might reduce the risk of patellofemoral instability by promoting early engagement of the patella in the trochlear during knee flexion.

Objective-To compare MR signal characteristics of contrast agent-labeled apoptotic and viable human mesenchymal stem cells (hMSCs) in matrix associated stem cell implants (MASI).Methods-hMSCs were labeled with FDA approved ferumoxides nanoparticles. One group (A) remained untreated while a second group (B) underwent Mitomycin C-induced apoptosis induction. Viability of group A and apoptosis of group B was confirmed by Caspase-assays and TUNEL stains. Labeled viable hMSCs, unlabeled viable hMSCs, labeled apoptotic hMSCs and unlabeled apoptotic hMSCs (n=7 samples each) in an agarose scaffold were implanted into cartilage defects of porcine patellae specimens and underwent MR imaging at 7T, using T1 weighted SE sequences, T2-weighted SE sequences and T2*-weighted GE sequences. Signal to noise ratios (SNR) of the implants were calculated and compared between different experimental groups using linear mixed regression models (LMM).Results-Ferumoxides-labeled hMSCs provided a strong negative T2 and T2*-enhancement. Corresponding SNR data of labeled hMSCs were significantly lower compared to unlabeled controls (p<0.05). Apoptosis induction resulted in a significant signal decline of ferumoxides-labeled hMSC transplants on short TE T2-weighted sequences. SNR data of labeled apoptotic hMSCs were significantly lower compared to labeled viable hMSCs (p<0.05).Conclusion-Apoptosis of transplanted ferumoxides-labeled stem cells in cartilage defects can be visualized non-invasively by a significant signal decline on T2-weighted MR images. The described MR signal characteristics may serve as a non-invasive outcome measure for the assessment of MASI therapies in clinical practice. Additional studies are needed to further enhance the observed differences between viable and apoptotic cells, e.g. by further optimizing the applied MR pulse sequence parameters or by determining more robust T2-relaxation times.

Purpose Kinematically aligned total knee arthroplasty (KA TKA) strives to restore the native distal and posterior joint lines of the femur. Because the joint lines of a virtually planned femoral component on the native femur can serve as surrogates of those of the native femur, the present study determined position and orientation deviations of the femoral joint lines following calipered KA TKA from virtually planned joint lines and whether these alignment deviations affect clinical outcomes. Our hypotheses were that the alignment deviations for most knees would be less than 2 mm and/or 2° and that larger alignment deviations would not be associated with lower clinical outcome scores. Methods A review of lower extremity CT scanograms and CT scans of the knee identified 36 patients treated with calipered KA TKA in one limb and no other skeletal deformities in either limb. 3D models of the operated femur with the implanted femoral component and the native femur were created. The articular surfaces of a 3D model of the implanted femoral component in the TKA knee were shape-matched to the condyles of the native femur to create a virtual plan. The shape-matched femoral component served as a reference from which to determine alignment deviations of the femoral component implanted in the ipsilateral femur. The Forgotten Joint Score (FJS) and Oxford Knee Score (OKS) were obtained at an average of 20 months. Results For proximal-distal and anterior-posterior positions and varus-valgus and internal-external orientations of the femoral component, the root mean square deviations from the planned joint lines ranged from 1.4 to 1.5 (mm or degrees). The mean differences ranged from − 0.1 to 0.2 (mm or degrees) indicating an absence of systematic alignment deviations. The proportion of knees with joint lines within ± 2 mm and ± 2° of the joint lines of virtually planned knees ranged from 83 to 92%. For the FJS and OKS, the median values were 79 (out of 100) and 45 (out of 48), respectively, and there were no significant correlations between deviations in the positions and orientations and either the FJS or the OKS. Conclusion Alignment deviations were bounded by 2 mm and 2° for most knees, which previous biomechanical studies have shown reduce the risks of stiffness, loss of extension, loss of flexion, and tibial compartment forces higher than those of the native knee. Moreover, because median FJS and OKS were relatively high, and because larger alignment deviations did not correlate with lower outcome scores, deviations did not affect clinical outcomes. These results validate calipered KA TKA as a surgical technique which closely restores the distal and posterior femoral joint lines to those planned and achieves concomitant high patient-reported outcome scores. Thus, surgeons can use the calipered KA TKA technique with confidence that the surgical alignment goal will be satisfied with sufficient accuracy that high patient-reported outcomes are achieved. Level of evidence III.

Background:Desmoplastic fibroma (DF) is an extremely rare locally aggressive bone tumor with an incidence of 0.11% of all primary bone tumors. The typical clinical presentation is pain and swelling above the affected area. The most common sites of involvement are the mandible and the metaphysis of long bones. Histologically and biologically, desmoplastic fibroma mimics extra-abdominal desmoid tumor of soft tissue.Case Presentation and Literature Review:A case of a 27-year old man with DF in the ilium, including the clinical, radiological and histological findings over a 4-year period is presented here. CT scans performed in 3-year intervals prior to surgical intervention were compared with respect to tumor extension and cortical breakthrough. The patient was treated with curettage and grafting based on anatomical considerations. Follow-up CT scans over 18-months are also documented here. Additionally, a review and analysis of 271 cases including the presented case with particular emphasis on imaging patterns in MRI and CT as well as treatment modalities and outcomes are presented.Conclusion:In patients with desmoplastic fibroma, CT is the preferred imaging technique for both the diagnosis of intraosseus tumor extension and assessment of cortical involvement, whereas MRI is favored for the assessment of extraosseus tumor growth and preoperative planning. While tumor resection remains the preferred treatment for DF, curettage and grafting prove to be an acceptable alternative treatment modality with close follow-up when resection is not possible. Curettage and grafting have been shown to provide good clinical results and are associated with long recurrence free intervals.