Summary

The authors describe a hybrid technique that involves a combination of open decompression and posterior lumbar interbody fusion (PLIF) and percutaneously inserted pedicle screws. This technique allows performance of PLIF and decompression via a midline incision and approach without compromising operative time and visualization. Further- more, compared to standard open decompression, this approach reduces post-operative wound pain because the small midline incision significantly reduces muscle trauma by obviating the need to dissect the paraspinal muscles off the facet joint complex and by avoiding posterolateral fusion, thus requiring limited lateral muscle dissection off the transverse processes. A series of patients with Grade I-II spondylolisthesis at L_4–5 and moderate–severe canal/ foraminal stenosis underwent midline PLIF at L_4–5, with closure of the midline incision. Percutaneous pedicle screws were inserted, thereby minimizing local muscle trauma, reduction of the spondylolisthesis being performed by using a pedicle screw construct. Rods were inserted percutaneously to link the L₄ and L₅ pedicle screws. Image intensifi- cation was used to confirmed satisfactory screw placement and reduction of spondylolisthesis. The results of a prospective study comparing a standard open decompression and fusion technique for spondylolisthesis versus the minimally invasive hybrid technique are discussed. The minimally invasive technique resulted in shorter hospital stay, earlier mobilization and reduced postoperative narcotic usage. The long-term clinical outcomes were equivalent in the two groups.

Summary

BACKGROUND
A 62-year-old man was referred for evaluation of back pain and worsening leg pain, which included neurogenic claudication and radicular pain in the left L3 distribution. The duration of his symptoms was approximately 2 months. There was erectile dysfunction and recent changes to his bowel habit. The patient noted that he had suffered a vertebral fracture (L2) after a fall several years previously, but could not identify any trauma at the time his symp- toms began. He reported no history of fever and no difficulty with urination. Significant medical history was hypertension and lower limb deep venous thrombosis, for which he was treated with warfarin for 6 months during the preceding year. There was no history of malignancy.

On examination, there was full power in all lower limb myotomes. There was a patchy decrease in sensation to the left lower limb. Reflexes were symmetric, and his gait was unremarkable.

INVESTIGATIONS
A CT scan of the lumbar spine showed an extra- dural lesion at L3 with adjacent ligamentum flavum hypertrophy and significant canal stenosis. There was an old compression fracture noted at the super- ior end plate of L2. MRI confirmed the presence of a solitary, well-defined lesion measuring

26×15×12 mm (craniocaudal × transverse × anteroposterior) adjacent to the lamina of L3 with intermediate intensity on T1-weighted and T2-weighted images. There was significant enhancement with gadolinium-based contrast ( figure 1). These findings were suggestive of an extradural tumour.

CT of the chest, abdomen and pelvis was per- formed. No evidence of malignancy was observed.

DIFFERENTIAL DIAGNOSIS
The traditional differential diagnosis of a spinal mass divides lesions into three groups according to their location. Intradural intramedullary masses arise within the spinal cord itself. Intradural extra- medullary masses arise outside of the spinal cord but within the thecal sac. Extradural (or epidural) masses arise outside the thecal sac, for example, in vertebral bone.

Our patient had an extradural mass which showed marked contrast enhancement. Coupled with the history of progressive symptoms, the leading differentials were a metastatic lesion, extra- dural meningioma or other extradural primary tumour. A facet joint cyst, with or without haemor- rhagic complication, was also considered, although the radiological findings were atypical.

Summary

Summary

Degenerative lumbar spondylolisthesis is a challenging clinical entity.When associated with lumbar canal and/or foraminal stenosis, patients present with claudicant and/or radicular symptoms, respectively. Surgical intervention provides more positive outcomes than conservative management. The spondylolisthesis arm of the spine patient outcomes research trial (SPORT) concluded that in a non-randomized as-treated environment (with control of potentially confounding baseline factors), after 2 years outcomes were significantly better in regards to pain and function for patients with degenerative spondylolisthesis and spinal stenosis than for those treated non-surgically (SPORT Trial)¹. The correlation with mechanical low back pain is less clear and will not be discussed here.

Summary

Cervico-thoracic kyphosis can develop in association with degenerative processes, systemic disease (ankylosing spondylitis, rheumatoid arthritis), tumour, congenital disorders, post-surgery, and after traumatic injury.1 The kyphosis can be functionally and emotionally debilitating in terms of pain and progressive neurological deficit, and when severe can present a difficult challenge for surgical correction. We report a female patient with a severe fixed deformity who was treated using a multi-level multi-stage approach.

Summary

The earliest report of anterior lumbar interbody fusion (ALIF) was in 1932 by Capener, who described its use in surgical management of spondylolisthesis¹ Subsequent reports were byMercer for the treatment of disc pathology²and Burns in 1933³. Its many advantages over posterior fusion, such as avoidance of paraspinal muscular injury, have resulted in increasing popularity of ALIF procedures. Although abundant clinical studies assessing bone graft alternatives for anterior cervical discectomy and fusion have been published⁴, grafting options for ALIF are not well documented in the literature. Successful arthrodesis depends on numerous surgical and host factors, including selection of a bone graft with elements critical for bone regeneration. Osteogenic properties of a graft enable it to provide stemcells and osteoblasts directly to regenerating bone, whereas osteoinductive factors such as bone morphogenetic proteins (BMPs) and other growth factors stimulate differentiation of progenitor cells into osteoblasts and osteocytes for new bone formation. An osteoconductive scaffold containing hydroxyapatite and collagen facilitates neovascularization that supports and maintains bone growth^4–6. For fusions of the lumbar spine, autologous bone is the “gold standard” with which graft alternatives are compared because it encompasses these ideal properties, whilst also conferring minute risk of infection or host rejection and having excellent fusion rates. However, its disadvantages include donor site pain, blood loss, neurovascular injury, increased duration of hospital stay and limited availability^7–9. To bypass these complications, many alternatives with potential for better patient outcomes are emerging (Table 1). Unfortunately, a lack of published clinical trials specifically assessing ALIF procedures limits the number of graft options accepted as safe alternatives to autografts. Also of note is that authors’ definitions of “successful fusion” vary, which can influence claimed study outcomes.

Summary

Summary

OBJECTIVE
To illustrate a hybrid technique that involves a combination of open decompression and Posterior Lumbar Interbody Fusion (PLIF) and percutaneously placed pedicle screws. This technique allows for PLIF via a midline incision and approach, and decompression without compromise in operative time and visualisation. Furthermore, this approach is proposed to reduce post-operative wound pain by: smaller midline incision, significantly reduced muscle trauma by not dissecting the paraspinal muscles off the facet joint complex, avoidance of a posterolateral fusion to facilitate limited lateral muscle dissection off the transverse processes.

BACKGROUND
PLIF fusion rates are comparable to posterolateral fusion rates, as well as providing greater sagittal and coronal balance. There is positive evidence that degenerative spondylolisthesis with canal and/or foraminal stenosis requires stabilisation when decompressed via laminectomy.

METHODS
Patients with Grade I-II spondylolisthesis at L4/5 with moderate – severe canal/foraminal stenosis undergo a midline PLIF at L4/5, with closure of the midline incision. Percutaneous pedicle screws are inserted, therefore minimising local muscle trauma, with reduction of the spondylolisthesis performed using the pedicle screw construct. Rods are inserted percutaneously to link the L4 and L5 pedicle screws. Image intensification is used to confirmed satisfactory screw placement and reduction of the spondylolisthesis.

CONCLUSION
Percutaneous lumbar pedicle screws can be combined with a standard midline PLIF to reduce postoperative wound pain while allowing for satisfactory screw placement.

Summary

BACKGROUND
Percutaneous insertion of cannulated pedicle screws has been developed as a minimally invasive alternative to the open technique during instrumented fusion procedures of the thoraco-lumbar spine. The reported rate of screw misplacement using open techniques is well described, however data is lacking on the exact failure rate of the percutaneous technique.

METHODS
A total of 424 percutaneously inserted pedicle screws from 2007 to 2010 were analyzed in 88 patients, from a single surgeon series (RJM). Axial reformatted computer tomographic images were examined by 2 independent observers and individual and consensus interpretation was obtained for each screw position. A simple grading system was used for assessment of screw accuracy— Grade 0: screw within cortex of pedicle; Grade 1: screw thread breach of wall of pedicle < 2 mm; Grade 2: signifi cant breach > 2 mm with no neurological compromise; Grade 3: complication including pedicle fracture, anterior breach with neuro-vascular compromise, and lateral or medial breach with neurological sequelae.

RESULTS
The indications for percutaneous pedicle screw insertion include: degenerative (78%), trauma (13%), tumour (8%), and infection (1%). Pedicle screws were inserted into level T4 to S1. The most common levels performed include L4 and L5 with the most common indication for surgery being an L4/5 spondylolisthesis. 383 out of 424 screws (90.3%) were placed in the cortical shell of the pedicle (Grade 0). Forty-one screws (9.7%) were misplaced from T4 to S1. Of these, the majority were Grade 1 pedicle violations (24 screws; 5.7%), with 15 Grade 2 violations (3.5%) and 2 Grade 3 violations (0.5%). Of the 2 Grade 3 pedicle violations, both were pedicle fractures but only 1 had associated neurological defi cit (L4 radiculopathy postoperatively).

CONCLUSION
Percutaneous insertion of cannulated pedicle screws in the thoracic and lumbar spine is an acceptable technique with a low complication rate in experienced hands. The overall rate of perforation is below the higher rates reported in the literature for the open technique. Complication rates including pedicle fracture were low.