BACKGROUND: Controversy exists regarding surgical treatment of high-grade spondylolisthesis (HGS) in terms of decompression with surgical reduction or in situ fusion. In situ fusion has the advantage of being less technically demanding. However, the residual bone graft area is extremely limited, and posterolateral bone grafting is complex as the transverse process of the slipped vertebrae is located anterior to the sacral ala, which correlates with high rates of pseudoarthrosis. METHODS: Four cases of L5/S1 HGS complaining of low back pain were treated using our new bone graft technique with an exposed osseous end plate. Transdiskal screw holes were made from the S1 pedicle, and bone chips were packed into the L5/S disk space through the screw holes. The slipped L5 vertebra was fixed with a combination of L5/S1 transdiskal and L5 pedicle screws. RESULTS: All cases exhibited good bony fusion, and the low back pain disappeared in all patients up to the 12-month follow-up. This technique involved packing the bone into the closed space, relieving any concerns regarding bone graft migration. CONCLUSIONS: Transpedicular bone graft via transdiskal screw holes is an easy and practical technique for raising the fusion rate in surgical treatment of HGS.

We assessed whether there was a difference in attenuation measurements (in Hounsfield units – HU) and geometric distribution of HU between femora with metastatic lesions that fracture, and metastatic lesions that did not fracture nor underwent prophylactic fixation.Nine patients with femoral metastases who underwent CT and developed a pathological fracture were matched to controls. All femora were delineated in axial CT slices using a region of interest (ROI) tool; the HU within these ROIs were used to calculate: (1) the cumulative HU of the affected over the nonaffected side per slice and presented as a percentage, and (2) the cumulative HU accounting for geometric distribution (polar moment of HU). We repeated the analyses including cortical bone only (HU of 600 and above).CT-based calculations did not differ between patients with a lesion that fractured and those that did not fracture nor underwent prophylactic fixation when analyzing all tissue. However, when including cortical bone only, the pathological fracture group had a lower cumulative HU value compared to the no fracture and no fixation group for the weakest cross-sectional CT image (pathological fracture group, mean: 71, SD: 23 and no fracture and no prophylactic fixation group, mean: 85, SD: 18, p = 0.042) and the complete lesion analysis (pathological fracture group, mean: 78, SD: 21 and no fracture and no prophylactic fixation group, mean: 92, SD: 15, p = 0.032).The demonstrated CT-based algorithms can be useful for predicting pathological fractures in metastatic lesions.

We aimed to investigate the clinical performance of the constructs of double-door cervical laminoplasty with suture anchors by examining bony fusion at the hinges and lamina closure.

Fatty degeneration of the cuff muscles is usually evaluated at the Y-view in oblique sagittal images. It was recently proposed that muscle shift after repair may influence the fatty degeneration values, and the evaluation of the muscles at a more medial site was recommended. However, the differences in muscle quality in accord with measurement sites have been unclear. Here we evaluated differences in fatty degeneration of the rotator cuff muscles measured quantitatively at different sites, using T2 mapping.We assessed 702 shoulders of 675 patients (335 males, 340 females; mean age, 62 years) who underwent MRI including T2 mapping. There were 345 shoulders without rotator cuff tears and 357 shoulders with tears: partial tear = 103 shoulders; small = 63; medium = 94; large = 71; massive = 26. T2 values of the supraspinatus and infraspinatus muscles were measured on the Y-view and on the image that was 15 mm medial to the Y-view.The T2 values at the medial site increased with the tear extent, as did those on the Y-view. There were no significant differences in supraspinatus T2 values between those on the Y-view and at the medial site in all tear size groups except medium and large tears (p = 0.008 and p < 0.001, respectively). There were also no significant differences in infraspinatus T2 values between the two sites in all tear size groups except large tears (p = 0.002). However, the differences were relatively small (2.4–5.6 ms), which were within the standard deviations of the measurements.The T2 values of the supraspinatus and infraspinatus muscles on the Y-view and at 15 mm medial to it were almost identical, with the exception of small differences in the case of larger tears.

STUDY DESIGN:A cadaveric study.OBJECTIVE:To investigate the accuracy of pedicle screw placement using a robotic guidance system (RGS).SUMMARY OF BACKGROUND DATA:RGS is a unique surgery assistance-apparatus. Although several clinical studies have demonstrated that RGS provides accurate pedicle screw placement, very few studies have validated its accuracy.METHODS:A total of 216 trajectories performed with the assistance of the RGS in eight cadavers were evaluated. The RGS was used, with different mounting platforms, to drill pilot holes in the thoracic and lumbosacral spine, using 3-mm diameter fiducial wires as trajectory markers. Deviation between the preoperative plan and executed trajectories was measured at the entry points to the vertebrae and at a depth of 30 mm along the wire. Both the deviation from the preoperative plan and the wire position were evaluated in the axial and sagittal planes using computed tomography (CT).RESULTS:The average deviation from the planned wire placement was 0.64 ± 0.59 mm at the entry point and 0.63 ± 0.57 mm at a depth of 30 mm in the axial plane, and 0.77 ± 0.62 mm and 0.80 ± 0.66 mm, respectively, in the sagittal plane. The magnitude of deviation was not affected by the vertebral level or the platform used. The use of an open approach achieved greater screw placement accuracy at a depth of 30 mm in the sagittal plane, compared with the percutaneous approach. The fiducials were placed completely within the pedicle in 93.9% of trajectories in the axial plane (n = 164 pedicles with a width ≥5 mm) and 98.6% in the sagittal plane (n = 216).CONCLUSION:In this cadaveric study, RGS supported execution of accurate trajectories that were equal or slightly superior to reports of CT-based navigation systems.LEVEL OF EVIDENCE:N/A.