Preservation Of Posterior Structures Research Articles

Biomechanics of open-door laminoplasty with and without preservation of posterior structures.

OBJECTIVE Cervical open-door laminoplasty (ODL) is designed to decompress the spinal cord, maintain motion, and prevent postlaminectomy kyphosis. Many traditional laminoplasty techniques involve disruption of the posterior ligamentous structures, most notably the C7-T1 supraspinous ligament and interspinales muscle complex (intraspinous and supraspinous ligaments [ISLs]). METHODS Eight human cervical cadaveric specimens (C2-T1) were used to investigate the subaxial kinematics following ODL with varying degrees of posterior element disruption. Ligamentous integrity was preserved and specimens were tested utilizing force control in flexion-extension (FE), lateral bending (LB), and axial rotation (AR) in the native state, and following 1) C3-7 ODL, 2) ODL with terminal ISL resection, 3) ODL with C3-7 spinous process resection, and 4) C3-7 laminectomy. Range of motion (ROM) was measured across C2-T1, "global," and at the segmental level. RESULTS Compared with ODL, sectioning the terminal ISLs resulted in global ROM increases by 7.9% in FE, 2.4% in LB, and 5.6% in AR (p > 0.05), whereas laminectomy increased global ROM by 36.0% in FE (p = 0.002) and a 26.3% increase in AR ROM (p = 0.01). When considering segmental ROM, resection of the terminal ISLs increased ROM in FE by 36.5% at C2-3 (p = 0.019) and 25.4% at C7-T1 (p > 0.05). Segmental increases following C3-7 spinous process resection averaged less than 3% per level, compared with up to 40% increases in ROM per level after laminectomy. CONCLUSIONS Laminectomy resulted in the greatest increase in global cervical ROM. Resection of the ISLs at C2-3 and C7-T1 increased segmental ROM at these specific levels to a similar extent that laminectomy increased ROM at each cervical level. This segmental ROM may contribute to pain or postprocedural deformity and highlights the importance of the ISLs at the terminal ends of the ODL.

Open-Door Cervical Laminoplasty with Preservation of Posterior Structures

Objective To demonstrate that preservation of all posterior structures during open-door laminoplasty (ODL) is associated with a significant preservation of motion. Methods Fifteen patients underwent cervical ODL by one surgeon for treatment of cervical spondylotic myelopathy. An open-door technique was employed, and the laminae on the open side were reconstructed using miniplates with allograft strut bone graft. All spinous processes and interspinous and supraspinous ligaments were preserved within the operative levels and between supra- and subjacent levels in all patients. Postoperative radiographs were obtained 1.5, 3, 6, and 12 months. Computed tomography scans were obtained at 12 months. Results There were no significant intraoperative or perioperative complications. Postoperatively, the neutral angle was 6.8 ± 11.5 degrees (95% confidence interval: 0.5 to 13.1), representing a loss of lordosis of 3 degrees (not significant). The difference between the preoperative and postoperative arc range of motion was 5.96 ± 11.9 degrees (confidence interval: −0.62 to 12.5). The average percent loss of motion was 3.5% ± (0.1 to 6.9%). Four patients had an increased range of motion postoperatively. Conclusion Open-door laminoplasty with preservation of all posterior structures provides greater preservation of motion than has been previously described.

Modified Extended Trochanteric Osteotomy with Preservation of Posterior Structures

The purpose of the study was to describe the technique and the clinical results of the modified extended trochanteric osteotomy (ETO) with a lateral approach to the hip. This osteotomy differs from those previously described, as it preserves the posterior part of the greater trochanter and its attached external rotators, the aim of this modification being to minimize the rate of hip dislocation. We reviewed the results of 105 extended sliding trochanteric osteotomies performed between January 2000 to January 2008. The indication for surgery was aseptic loosening in 83 cases, periprosthetic fractures in 10 cases, stem fracture in 5 cases, infection in 5 cases and instability in 2 cases. Minimum follow up was 20 months (mean, 65; range, 20-120 months). Mean length of the osteotomy was 17.6 cm (range, 9-30 cm). Mean Harris hip score improved from 39 points preoperatively to 73 at last follow up. Six stems (6%) needed revision for loosening. There was one case (1%) of osteotomy nonunion, and one case (1%) of greater trochanteric fragment nonunion and escape. Four patients (4%) dislocated postoperatively.

Radiographic Changes of Adjacent Upper Segment Performed Short Segmental Lumbosacral Fusion - Does Total Laminectomy Influence Adjacent Upper Segmental Instability? -

Study Design: Retrospective study. Objectives: The purpose of this study was to compare factors that influence degenerative changes in patients undergoing total laminectomy and patients undergoing partial laminectomy. Summary of Literature Review: Lumbar or lumbosacral fusion with total or partial laminectomy may result in adjacent segment problems of the upper segment. However, the differences between the two procedures that may influence adjacent segment instability are still controversial. Materials and Methods: We evaluated 95 patients, followed up for at least 2 years, who had been treated with short level (at most 2 levels) posterior lumbar interbody fusion with pedicle fixation, secondary to spinal stenosis. Treatment procedures included total laminectomy (42 cases) and partial laminectomy (53 cases). We analyzed the preoperative status of the intervertebral discs (Thompson grade), difference of disc height, and difference between preoperative segmental sagittal angle and last follow-up sagittal angle. We excluded cases that required revision secondary to infection, nonunion, or hematoma formation. However, we included cases that required revision due to adjacent segmental problems during the follow-up period. Results: The mean age of the patients treated with total laminectomy was 59.0±10.9 years, and of the patients treated with partial laminectomy was 58.8±10.2 years. The preoperative Thompson grade showed no statistical difference. The difference in disc height and segmental sagittal angle between the preoperative and last follow-up examinations showed no statistical difference between the two groups. Conclusions: There was no significant difference in the radiographic or clinical outcomes based on removal or preservation of posterior structures. Nevertheless, we need further follow-up to evaluate adjacent segment degeneration.

骨形成的偏側椎弓切除術で加療した椎間孔内・外神経根障害例

We reviewed the clinical outcome of patients with entrapment radiculopathy at the foraminal and/or extraforaminal lesions, who underwent osteoplastic hemilaminectomy.The patients were eight men, aged 20 to 73 years (mean, 53.6 years), and the mean follow-up time was 7 months (3 to 16 months). The diagnoses were lumbar canal stenosis for 6, combined for 4, post laminectomy for 1, spondylolytic for 1, and lateral lumbar disc herniation for 2. Seven patients reported low back pain, and 8 had sciatica. The nerve roots involved were L4 in 1, and L5 in 7. In all the patients, osteoplastic hemilaminectomy was performed using an absorbable screw made from poly-L-lactic acid for the fixation of the osteotomized lamina.The mean preoperative JOA score of 11.0 was increased to 24.1 at the final follow-up. The recovery ratio was 50% or more for all the patients with a mean value of 73.8%. Two patients gained fusion of the osteotomized lamina, but 6 had not in the short follow-up period.Osteoplastic hemilaminectomy allows appropriate decompression for nerve roots involved under a wide visual field and preservation of posterior structures.