Minimally Invasive Spine (MIS) surgery has been increasingly used as an alternative surgical treatment to the conventional open spine surgery which requires a large (10-20cm) skin incision. It provides a key-hole approach, through small skin incisions (1-3cm) with minimal muscle disruption to perform the spinal surgery. MIS surgery allows faster patient recovery, reduces intraoperative blood loss and the need for post operative blood transfusion. It also decreases post-operative pain. MIS surgical patients who go through MIS surgery have a shorter hospital stay when compared to patients with open surgical approach.
MIS surgical techniques have evolved in the last decade. At University Spine Centre, we have made MIS surgery effective, accurate and safe by employing the latest surgical techniques involving high resolution surgical microscope, intraoperative radiological imaging and surgical navigation system. With the technological advancements, MIS surgeries can be performed successfully on selected patients with a variety spinal disorder including, 1) prolapsed intervertebral disc, 2) spinal stenosis with spinal instability / spondylolisthesis, 3) spinal fractures from high velocity trauma, osteoporosis and spinal tumour, and 4) spinal deformity in both children and adult scoliosis spinal deformity surgery.
Figure 1. This show a typical MIS surgical spinal decompression using high resolution operating microscope, and a percutaneous a "key-hole" MIS approach.
1. Prolapsed Intervertebral Disc (PID) or "Slipped Disc"
Prolapsed intervertebral disc (PID) is a common spinal disorder that occurs in young adults. Patients will experience pain that radiates from the back down to the leg as the intervertebral disc content (nucleus pulpous) is compressing on the spinal nerve.
Figure 2. This is a diagrammatic representation of prolapsed and extruded intervertebral disc.
Minimally Invasive Spine (MIS) discectomy requires the use of small 1-2cm tubular retractor, operative microscope or endoscopes. Utilising an off-centre, paraspinal muscle splitting technique, a hole is created at the back of the spinal bone (laminotomy) and the prolapsed disc is then removed through this hole.
Figure 3A Figure 3B
Figure 3A and 3B shows MIS discectomy being performed using the tubular retract on the patient's back (Figure 3A) and the tubular retractor position on spinal intraoperative fluoroscopy to confirm its correct placement.
Figure 3C. This showed MIS discectomy performed using an endoscope.
2. Spinal Stenosis with Spondylolistesis
Lumbar Spinal stenosis refers to spinal canal narrowing and this results in spinal nerve compression in the lumbar spine. This typically occurs in elderly patients and is characterised by pain that radiates from patient's back down to the legs upon walking only. Lumbar spinal stenosis is often addociates with lumar spondylolistheisis and spinal segmental instability.
Figure 4A Figure 4B
Figure 4A shows a normal wide lumbar spinal canal and Figure 4B showed a narrowed spinal canal.
Figure 4C showed L5 on S1 spondylolisthesis. (i.e. L5 vertebral body is slipped forward in front of the S1 vertebral body on the side way lumbar spine x-ray.)
Transforaminal Lumbar Interbody Fusion (TLIF) is a common surgical procedure used in the treatment of spinal stenosis with spondylolisthesis. MIS TLIF involves a near total discectomy performed via tubular retractor. This is followed by the insertion of the interbody lumbar fusion cage into the empty disc space and percutaneous spinal pedicle screws insertion.
Figure 5A Figure 5B Figure 5C Figure 5D
Figure 5A showed TLIF on a AP lumbar spinal X ray, Figure 5B showed TLIF in a spinal model orientated in a frontal view. Figure 5C showed TLIF on a lateral lumbar spine X ray, Figure 5D showed TLIF in spinal model orientated in an oblique view.
Figure 6A Figure 6B
Figure 6A showed a MIS TLIF with lumbar cage being inserted via a 2.4cm wide tubular retractor and 2 percutaneous spinal pedicle screws inserted opposite to the tubular retractor. Figure 6B showed the lateral view of a MIS TLIF.
3. Spinal Fracture
Spinal fractures can be caused by a number of conditions, these includes high velocity trauma, osteoporosis or spinal tumour (metastasis). Surgical treatment of each spinal fracture is different.
In most of the osteoporotic compression fracture that do not respond to analgesia, MIS vertebroplasty or kyphoplasty may be the treament of choice. MIS vertebroplasty involves the injection of bone cement via spinal needles inserted through 1-2mm skin incisions over the osteoporotic fractured spine under fluoroscopic X ray guidance. Kyphoplasty is a variation of the MIS vertebroplasty technique.
Figure 7A Figure 7B
Figure 7A showed the white coloured spinal cement was inserted into the spine through 1-2mm skin incision. Figure 7B showed the injection of the spinal cement via spinal needles in 2 fractured spinal vertebral bodies on the lateral spine X ray.
Spinal fracture resulting from high velocity injury or spinal metastasis (tumour spread from elsewhere in the body) without nerve damage may be treated by MIS spinal pedicle screws instrumentation and spinal fracture stabilisation. This is achieved through percutaneous insertion of multiple pedicle screws over small 1.5cm incisions above and below the spinal fracture under fluoroscopic X rays guidance. Connecting rods are then inserted via the MIS approach to connect the pedicle screws to stabilise the spine fracture.
Figure 8A Figure 8B Figure 8C
Figure 8D Figure 8E
Figure 8A showed multiple spinal pedicle screws were inserted via MIS technique with fluoroscopic guidance. Figure 8B showed a lateral x ray view of a collapsed T12 spinal fracture with abnormal kyphotic spinal alignment, Figure 8C showed the collapsed T12 and abnormal spinal alignment were restored by the insertion of the MIS spinal implants. Figure 8D and 8E showed the AP view of the spine before and after MIS screws insertions, respectively.
4. Spinal Deformity (Scoliosis, Kyphosis, Kyphoscoliosis)
Spinal deformity is a spectrum of medical conditions affecting the straight alignment of the normal human spine. It can occur in both paediatric (children) and adult populations and has different clinical manifestations. The deformity can occur in any region along the spine and cannot be corrected by postural adjustment.
The primary aim for spinal deformity treatment is to arrest the progression of the scoliosis and to maintain a balanced spinal alignment (not necessary a straight spine). Uncontrolled scoliosis progression may result in a large scoliotic deformity that may lead to restrictive cardiac (heart) or pulmonary (lung) functions and lead to global spinal imbalance.
Surgical treatment is indicated in scoliotic curves that are more than 40 degrees in a growing child (skeletal immature spine) or in any person that has curves of more than 50 degrees. Surgery aims to fuse (join together) the vertebrae in a balanced spinal alignment to correct spinal imbalance and to arrest deformity progression. This is usually performed via a long skin incision along the back of the spine (posterior spinal approach) and the application spinal metal implants to hold the spine in position (Figure 9). In suitable patients, the surgery can be performed through thoracoscopic "keyhole" or Minimally Invasive Spine (MIS) surgery that require only 4 to 5 small incisions through the right side of the chest wall (anterior spinal approach) (Figure 10). Decompression of the compromised nerve is often indicated as part of the surgical treatment in adult degenerative scoliosis.
Figure 9. Open Posterior Spinal Approach
Figure 10. MIS Anterior Spinal (Thoracoscopic) approach
