PurposePatellofemoral instability is a common cause of anterior knee pain in adolescents and young adults. Most normal and pathological values for diagnosing patellofemoral instability are based on Western literature. We conducted this radiological study to determine normal values for different patellofemoral parameters in a Korean population and to evaluate their usefulness in diagnosis.Materials and MethodsWe retrospectively reviewed the rotational profile computerized tomography (CT) scans of the patellar dislocation and control groups. Trochlear, patellar, rotational profile, and trochleo-patellar alignment parameters were compared between the groups. Receiver operating characteristic curves were drawn for significant parameters, and sensitivity and specificity were calculated for the cut-off values.ResultsThere were 48 patients in the patellar dislocation group and 87 patients in the control group. In the control group and patellar dislocation group, the mean sulcus angle was 132.5° and 143.3°, respectively, trochlear depth was 6.04 mm and 3.6 mm, bisect offset was 56.4% and 99.9%, lateral patellar tilting was 9.8° and 19.2°, patellar facet asymmetry was 63.5% and 45.16%, and the tibial tuberosity-trochlear groove (TT-TG) distance was 10.91 mm and 27.16 mm, respectively.ConclusionsThe trochlear depth, bisect offset, patella tilting, and TT-TG distance were parameters that significantly contributed to patellar instability. Rotational profile CT can be considered a good diagnostic tool to assess all these parameters that help to identify anatomical aberration resulting in patellofemoral instability, thereby helping in formulating the most effective treatment plan.

The DB technique, compared with SB, was not more effective in preventing OA and did not have a more favorable failure rate. Although the DB ACLR technique produced a better IKDC subjective scale result than did the SB ACLR technique, the 2 modalities were similar in terms of clinical outcomes and stability after a minimum 4 years of follow-up.

Three-dimensional (3D) printing technology is additive manufacturing that produces 3D shapes by stacking twodimensional (2D) cross-sectional shapes with various materials. It is used for laminated manufacturing, such as rapid prototyping (RP). In the early days, there were a number of key limitations in printing materials, molding time, size, precision and strength of the moldings, which limited industrial uses. In recent years, however, printing materials have been diversified including metals, and printing equipment has been developed accordingly. The paradigm of industrial use is rapidly changing as the production of complex shapes and customized products become possible. Today, 3D-printing technology can be used to create simulation models or medical implants, thus significantly aiding doctors and medical companies by optimizing the

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Sequential bilateral hip fractures (SBHF) have been reported with increasing frequency in elderly and osteoporotic patients 1) . Patients with SBHF have greater mortality, reduced functional abilities, limited mobility and seldom recover to their preoperative mobility levels [2][3][4] , therefore, it is crucial to fully understand SBHF, so that preventive and treatment strategies can be developed and initiated after an initial hip fracture, especially in elderly patients.Numerous studies have described the clinical presentation and outcomes of SBHF, however, to date, studies of incidence and presentation of SBHF in Korea are scarce (n=3) and results are variable [5][6][7] . To help fill this knowledge gap, this study was conducted to investigate the following: (i)