Modified muscle-sparing paraspinal approach for stabilization and interlaminar decompression: a minimally invasive technique for pedicle screw-based posterior nonfusion stabilization.

INTRODUCTION: Though Wiltse developed the paraspinal muscle-splitting approach to the spine, the exact location of where and how to split the paraspinal musculature when performing this approach remains unclear. This type of approach may be particularly useful for posterior nonfusion stabilization as significantly less damage occurs with this approach than with a muscle-stripping approach. METHODS: We use the term "modified muscle-sparing approach" to describe our technique for following the natural cleavage plane between the multifidus and longissimus muscles to access the spine. We review the rationale behind this methodology and describe technical aspects of this approach and also demonstrate the technique on video. RESULTS: We use this technique routinely for our posterior nonfusion pedicle screw stabilization approach. CONCLUSIONS: The modified muscle-sparing approach is a useful approach for insertion of pedicle screw-based posterior nonfusion stabilization. The approach can be readily performed with little blood loss and with little muscle damage. Decompression can also be performed through the same incision if needed.

Benefits of the paraspinal muscle-sparing approach versus the conventional midline approach for posterior nonfusion stabilization: comparative analysis of clinical and functional outcomes.

BACKGROUND: The influence of approach on outcomes of posterior nonfusion stabilization has not been described. This paper analyzes the influence of surgical approach on functional outcome with nonfusion stabilization. METHODS: We performed a prospective consecutive cohort outcome analysis of 88 patients who had undergone posterior nonfusion stabilization of the lumbar spine at 178 levels using the Dynesys system (Zimmer Spine, Inc, Warsaw, Indiana). Patients needing decompression (n = 42) were operated through a midline approach using microscopic laminotomy/foraminotomy with or without discectomy, followed by posterior nonfusion stabilization with Dynesys. None of the patients had a complete laminectomy. Patients not needing decompression (n = 46) underwent the procedure via the bilateral paraspinal muscle-sparing approach and were subsequently stabilized. Clinical and functional outcomes data were collected using the visual analog scale (VAS), Treatment Intensity Score (TIS), Oswestry Disability Index (ODI), and SF-36. Average follow-up was 18 months (range, 12-36 mo). RESULTS: All outcome measures in both groups showed significant improvement at last follow-up. Between the groups a significant difference was apparent in the reduction of the TIS when measured at 1 week and 6 weeks. The preoperative, 1-week, and 6-week values were 66, 48, and 40, respectively (P < 0.05), for the midline group and 80, 32, and 28 (P < 0.05) for the paraspinal group. This trend continued through 3 to 6 months after the procedure but did not reach statistical significance. In the paraspinal group, pain scores showed a nonsignificant trend toward lower values in the first month, compared with values in the midline group. Patients reported excellent to fair results, with the exception of three patients in the midline group and two in the paraspinal group, who rated the procedure as fair. CONCLUSIONS: Significantly fewer patients required postoperative narcotics in the paraspinal group than in the midline group. This improvement in early outcomes suggests a significant early benefit to the less tissue-destructive muscle-sparing approach in posterior nonfusion stabilization procedures.

The changing role for neurosurgeons and the treatment of spinal deformity.

Spinal deformity has classically and historically been studied by those in the discipline of orthopedic surgery. This may be attributable to the orthopedic interventionalists' experience with osseous fixation for long-bone and other skeletal fractures. Neurosurgeons have maintained a long-standing interest in complex cervical spinal disorders, and their interest in the larger field of complex spinal deformity has been expanding. An understanding of spinal deformity disorders, biomechanics, bone biology, and metallurgy is necessary before clinical, teaching, and research activities can be undertaken within neurosurgery. The authors describe basic and advanced concepts of spinal deformity management with cases to illustrate teaching points.

Posterior atlantoaxial stabilization: new alternative to C1-2 transarticular screws.

OBJECT: Surgical treatment of atlantoaxial instability has evolved to include various posterior wiring techniques including Brooks, Gallie, and Sonntag fusions in which success rates range from 60 to 100%. The Magerl-Seemans technique in which C1-2 transarticular screws are placed results in fusion rates between 87 and 100%. This procedure is technically demanding and requires precise knowledge of the course of the vertebral arteries (VAs). The authors introduce a new C1-2 fixation procedure in which C-1 lateral mass and C-2 pedicle screws are placed that may have advantages over C1-2 transarticular screw constructs. METHODS: A standard posterior C1-2 exposure is obtained. Polyaxial C-2 pedicle screws and C-1 lateral mass screws are placed bilaterally. Rods are connected to the screws and secured using locking nuts. A cross-link is then placed. Fusion can be performed at the atlantoaxial joint by elevating the C-2 nerve root. The technique for this procedure has been used in four cases of atlantoaxial instability at the author's institution. There have been no C-2 nerve root- or VA-related injuries. No cases of construct failure have been observed in the short-term follow up period. CONCLUSIONS: Atlantoaxial lateral mass and axial pedicle screw fixation offers an alternative means of achieving atlantoaxial fusion. The technique is less demanding than that required for transarticular screw placement and may avoid the potential complication of VA injury. The cross-linked construct is theoretically stable in flexion, extension, and rotation. Laminectomy or fracture of the posterior elements does not preclude use of this fixation procedure.