Hines JT, et al. J Korean Med Sci. 2021 May;36(24):e177. https://doi.org/10.3346/jkms.2021.36.e177

Sugano N. Clin Orthop Surg. 2013 Mar;5(1):1-9. http://dx.doi.org/10.4055/cios.2013.5.1.1

We propose a method for automatic segmentation of individual muscles from a clinical CT. The method uses Bayesian convolutional neural networks with the U-Net architecture, using Monte Carlo dropout that infers an uncertainty metric in addition to the segmentation label. We evaluated the performance of the proposed method using two data sets: 20 fully annotated CTs of the hip and thigh regions and 18 partially annotated CTs that are publicly available from The Cancer Imaging Archive (TCIA) database. The experiments showed a Dice coefficient (DC) of 0.891±0.016 (mean±std) and an average symmetric surface distance (ASD) of 0.994±0.230 mm over 19 muscles in the set of 20 CTs. These results were statistically significant improvements compared to the state-of-the-art hierarchical multi-atlas method which resulted in 0.845±0.031 DC and 1.556±0.444 mm ASD. We evaluated validity of the uncertainty metric in the multi-class organ segmentation problem and demonstrated a correlation between the pixels with high uncertainty and the segmentation failure. One application of the uncertainty metric in activelearning is demonstrated, and the proposed query pixel selection method considerably reduced the manual annotation cost for expanding the training data set. The proposed method allows an accurate patient-specific analysis of individual muscle shapes in a clinical routine. This would open up various applications including personalization of biomechanical simulation and quantitative evaluation of muscle atrophy.

We have developed a CT-based navigation system using infrared light-emitting diode markers and an optical camera. We used this system to perform cementless total hip replacement using a ceramic-on-ceramic bearing couple in 53 patients (60 hips) between 1998 and 2001. We reviewed 52 patients (59 hips) at a mean of six years (5 to 8) postoperatively. The mid-term results of total hip replacement using navigation were compared with those of 91 patients (111 hips) who underwent this procedure using the same implants, during the same period, without navigation. There were no significant differences in age, gender, diagnosis, height, weight, body mass index, or pre-operative clinical score between the two groups. The operation time was significantly longer where navigation was used, but there was no significant difference in blood loss or navigation-related complications. With navigation, the acetabular components were placed within the safe zone defined by Lewinnek, while without, 31 of the 111 components were placed outside this zone. There was no significant difference in the Merle d’Aubigne and Postel hip score at the final follow-up. However, hips treated without navigation had a higher rate of dislocation. Revision was performed in two cases undertaken without navigation, one for aseptic acetabular loosening and one for fracture of a ceramic liner, both of which showed evidence of neck impingement on the liner. A further five cases undertaken without navigation showed erosion of the posterior aspect of the neck of the femoral component on the lateral radiographs. These seven impingement-related mechanical problems correlated with malorientation of the acetabular component. There were no such mechanical problems in the navigated group. We conclude that CT-based navigation increased the precision of orientation of the acetabular component and control of limb length in total hip replacement, without navigation-related complications. It also reduced the rate of dislocation and mechanical problems related to impingement.

Cui Q, et al. J Korean Med Sci. 2021 Feb;36(10):e65. https://doi.org/10.3346/jkms.2021.36.e65

D. Methods: Twenty-five consecutive patients (thirty-three hips) who had previously had Crowe Group-IV developmental dysplasia of the hip were treated with a modular cementless prosthesis at a mean age of sixty years. The mean follow-up period was eight years (range, five to eleven years). The acetabular cup was placed in the position of the anatomical hip center in every patient. Subtrochanteric femoral shortening osteotomy was performed with use of a step-cut design. Results: The mean Merle d’Aubigné and Postel hip score improved from 9 to 16 points (out of a maximum of 18 points). The mean limb-length discrepancy in seventeen patients with unilateral involvement was reduced from 5.1 cm (range, 3.7 to 6.5 cm) to 2.8 cm (range, 1.4 to 4.6 cm). Two patients had a positive Trendelenburg sign, and three had a slight limp at the time of the latest follow-up. No cases of nonunion or nerve palsy were encountered. Postoperative dislocations occurred in two hips. One hip showed progressive radiolucent lines around the proximal femoral sleeve within two years after the surgery, and this was followed by progressive stem subsidence. Only one femoral stem was revised. Conclusions: Cementless, modular total hip arthroplasty combined with subtrochanteric osteotomy for the treatment of patients with prior Crowe Group-IV developmental dysplasia of the hip resulted in satisfactory outcomes. Hips with poor bone quality and a developmentally short femoral neck present technical challenges with regard to achieving sufficient rotatory stability, following osteotomy, for osseointegration of the modular implants. Level of Evidence: Therapeutic Level IV. See Instructions to Authors for a complete description of levels of evidence....