Field-of-view enhanced integral imaging with dual prism arrays based on perspective-dependent pixel mapping.

A field-of-view (FOV)-enhanced integral imaging system is proposed by the combined use of micro-lens array (MLA) and dual-prism array (DPA). The MLA coupled with a DPA virtually function as a new type of the MLA whose FOV is much more increased than that of the original MLA, which enables the capturing of perspective-expanded elemental image arrays (EIAs) of input 3-D scenes and the FOV-enhanced reconstruction of them. For its practical operation, a two-step digital process called perspective-dependent pixel-mapping (PDPM) is also presented. With this PDPM method, picked-up EIAs with a couple of MLAs and DPAs are remapped into the new forms of EIAs to be properly reconstructed in the conventional integral imaging system. Operational performances of the proposed system are ray-optically analyzed. In addition, the feasibility of the proposed system is also confirmed from the computational and optical experiments with test 3-D objects on the implemented prototype. Experimental results finally show a two-times increase of the FOV range of the proposed system when it is compared with that of the conventional system.

Analysis of potential distortions corresponding to the hologram printed by a holographic wave-front printer.

In this paper, potential distortions corresponding to the hologram printed by a holographic wave-front printer are analyzed. Potential distortions are classified as the magnification(demagnification) distortion, barrel distortion, pincushion distortion, SLM mounting distortion, and translation distortion, respectively. These distortions are grouped as the optics distortion, SLM mounting distortion and the translation distortion depending on the process of recording the hologram in the holographic wave-front printer. In order to evaluate each distortion, a distortion analysis method based on a local spatial frequency is proposed. Through the proposed method, a diffracted wavefield reconstructed from a quantitatively distorted hologram is theoretically analyzed, and the validity of this analysis is verified by applying the numerical reconstruction method. In the numerical reconstruction, a propagation of a distorted wavefield reconstructed from the quantitatively distorted hologram is confirmed and contributed to generate the distorted reconstruction plane, such as a focal cloud plane and a convergence plane, depending on the types of distortion.

Accelerated Fusion Dynamics by Recombinant Human Bone Morphogenetic Protein-2 Following Transforaminal Lumbar Interbody Fusion, Particularly in Osteoporotic Conditions.

BACKGROUND CONTEXT: Early fusion is crucial in interbody procedures to minimize mechanical complications resulting from delayed union, especially for patients with osteoporosis. Bone morphogenetic proteins (BMPs) are used in spinal fusion procedures; however, limited evaluation exists regarding time-to-fusion for BMP use, particularly in patients with osteoporosis. PURPOSE: To evaluate the difference in time-to-fusion after single-level transforaminal lumbar interbody fusion (TLIF) surgery between recombinant human bone morphogenetic protein-2 (rhBMP-2) usage and non-usage groups according to bone density. STUDY DESIGN: Retrospective single-center cohort study PATIENT SAMPLE: This study enrolled 132 patients (mean age, 65.25±8.66; male patients, 40.9%) who underwent single-level TLIF for degenerative disorders between February 2012 and December 2021, with pre- and postoperative computed tomography (CT). OUTCOME MEASURE: The interbody fusion mass and bone graft status on postoperative CT scans was obtained annually, and time-to-fusion was recorded for each patient. METHODS: The patients were divided into two groups based on rhBMP-2 use during the interbody fusion procedure. Patients were further divided into osteoporosis, osteopenia, and normal groups based on preoperative L1 vertebral body attenuation values, using cutoffs of 90 and 120 Hounsfield units. It was strictly defined that fusion is considered complete when a trabecular bone bridge was formed, and therefore, the time-to-fusion was measured in years. Time-to-fusion was statistically compared between BMP group and non-BMP groups, followed by further comparison according to bone density. RESULTS: The time-to-fusion differed significantly between BMP and non-BMP groups, with half of the patients achieving fusion within 2.5 years in the BMP group compared with 4 years in the non-BMP group (p < 0.001). The fusion rate varied based on bone density, with the maximum difference observed in the osteoporosis group, when half of the patients achieved fusion within 3 years in the BMP group compared to 5 years in the non-BMP group (p < 0.001). Subgroup analysis was conducted, revealing no significant associations between time-to-fusion and factors known to influence the fusion process, including age, gender, medical history, smoking and alcohol use, and medication history, except for rh-BMP2 use and bone density. CONCLUSIONS: RhBMP-2 usage significantly reduced time-to-fusion in single-level TLIF, especially in patients with osteoporosis. LEVEL OF EVIDENCE: Level III.

Long-Term Incidence of Adjacent Segmental Pathology After Minimally Invasive vs. Open Transforaminal Lumbar Interbody Fusion.

STUDY DESIGN: Retrospective cohort study. OBJECTIVE: To compare the incidence of adjacent segmental pathology (ASP) following minimally invasive (MI) vs open transforaminal lumbar interbody fusion (TLIF) and to identify factors linked to ASP requiring reoperation. METHODS: This retrospective study reviewed the outcomes of patients who underwent MI-TLIF or open TLIF. Radiographic ASP (RASP) was evaluated using X-ray imaging to distinguish between degenerative changes, spondylolisthesis, and instability in the adjacent spinal segment. Clinical ASP (CASP) was assessed with the visual analog scale score for leg and back pain and the Oswestry disability index. Patient data were collected 1, 2, 5, and 10 years postoperatively. The timing and frequency of ASP reoperation were analyzed. RESULTS: Five years postoperatively, the RASP rate was 35.23% and 45.95% in the MI-TLIF and open TLIF groups. The frequency of CASP differed significantly between the MI-TLIF and open TLIF groups at 1 year postoperatively. The rates of RASP, CASP, and ASP necessitating reoperation were not significantly different 10 years postoperatively. Cranial facet violation significantly affected ASP in both groups. In the open TLIF group, preoperative adjacent segment disc degeneration significantly influenced ASP. CONCLUSION: The RASP rate at 5 years postoperatively and the CASP rate at 1 year postoperatively differed significantly between groups. There was no difference in the rate of ASP requiring reoperation. Cranial facet violation is a crucial driving factor for ASP after both surgical procedures.

Index Finger Flexor Digitorum Profundus Function Deficit after Shoulder Arthroscopy Treated by Neurolysis: A Case Report.

A 60-year-old woman presented functional deficit of the index finger flexor digitorum profundus (FDP) tendon after shoulder arthroscopic rotator cuff repair. As no recovery was observed for 10 months, we conducted an operative exploration of the median nerve and the anterior interosseous nerve, followed by an external neurolysis. The patient recovered FDP function 4.5 months after the second operation. In a patient with persistent isolated FDP dysfunction after shoulder arthroscopy, operative exploration and external neurolysis could facilitate functional recovery. Level of Evidence: Level V (Therapeutic).

Combined PCL and PLC Reconstruction Improves Residual Laxity in PCL Injury Patients with Posterolateral Knee Laxity Less Than Grade III.

PURPOSE: To compare the short-term clinical and radiologic outcomes of combined posterior cruciate ligament (PCL) and posterolateral complex (PLC) reconstruction to those of isolated PCL reconstruction (PCLR) for patients with posterolateral knee laxity less than grade III. MATERIALS AND METHODS: We retrospectively reviewed 49 patients (51 knees) who underwent PCLR between January 2008 and December 2015. Patients with a minimum follow-up of 24 months were included and divided into two groups (group A, isolated PCLR; group B, combined PCL and PLC reconstruction). Clinical outcomes were evaluated as the International Knee Documentation Committee (IKDC) subjective, Lysholm, and Tegner activity scale scores. Radiologic outcomes were also assessed using the side-to-side differences in posterior tibial translation via stress radiographs. RESULTS: A total of 30 cases were analyzed. There were no significant differences in the Lysholm and Tegner activity scale scores between the two groups preoperatively and at the final follow-up. However, group B showed a higher IKDC subjective score compared to group A at the final follow-up (group A, 72.8±8.9; group B, 77.7±10.1; p<0.05). Regarding the radiologic outcomes, group B also showed a significantly less side-to-side difference in posterior tibial translation compared to group A at the final follow-up (group A, 4.8±2.3 mm; group B, 3.8±2.1 mm; p<0.05). CONCLUSION: Combined PCL and PLC reconstruction resulted in improved clinical and radiologic outcomes than isolated PCLR in patients who have less than grade III posterolateral laxity of the knee. In cases of PCL rupture with ambiguous PLC injury, combined PCL and PLC reconstruction may help to improve posterior residual laxity of the knee.