OBJECTIVE Minimally invasive techniques are being increasingly used to treat disorders of the cervical spine. They have a potential to reduce the postoperative neck discomfort subsequent to extensive muscle dissection associated with conventional atlantoaxial fusion procedures. The aim of this paper was to elaborate on the technique and results of minimally invasive atlantoaxial fusion. MATERIALS Minimally invasive atlantoaxial fusion was done initially in 4 fresh-frozen cadavers and subsequently in 5 clinical cases. Clinical cases included patients with reducible atlantoaxial instability and undisplaced or minimally displaced odontoid fractures. The surgical technique is illustrated in detail. RESULTS Among the cadaveric specimens, all C-1 lateral mass screws were in the correct position and 2 of the 8 C-2 screws had a vertebral canal breach. Among clinical cases, all C-1 lateral mass screws were in the correct position. Only one C-2 screw had a Grade 2 vertebral canal breach, which was clinically insignificant. None of the patients experienced neurological worsening or implant-related complications at follow-up. Evidence of rib graft fusion or C1–2 joint fusion was successfully demonstrated in 4 cases, and flexion-extension radiographs done at follow-up did not show mobility in any case. CONCLUSIONS Minimally invasive atlantoaxial fusion is a safe and effective alternative to the conventional approach in selected cases. Larger series with direct comparison to the conventional approach will be required to demonstrate clinical benefit presumed to be associated with a minimally invasive approach.

Background: Cervical radiculopathy is a common pathological entity encountered by spine surgeons. Many surgical options have been described including anterior cervical discectomy with or without fusion to arthroplasty and posterior cervical laminoforaminotomy. Being a motion-preserving procedure, posterior cervical laminoforaminotomy is an excellent treatment for patients with unilateral radiculopathy secondary to a laterally located herniated disc or foraminal stenosis. With the advent of minimally invasive techniques, this procedure has regained popularity. Objectives: Although there is enough evidence in the literature highlighting the benefits, safety, and efficacy of minimally invasive versus conventional techniques, a detailed technical report along with long-term surgical outcomes is lacking. Methods: The authors present their experience in minimally invasive cervical laminoforaminotomy (MIS-CLF) over a 7-year period (2013–2020) along with a technical note. Clinical evaluation was performed both before and after surgery, using the Visual Analog Scale (VAS) pain scores. Patient functional outcome was measured using the modified Odom's criteria. Results: There were no major perioperative complications. No patient required surgery for the same level during the follow-up period which ranged from 1 to 3 years. Statistically significant results were obtained in all cases, reflected by an improvement in VAS for neck/arm pain. Conclusion: MIS-CLF is an effective technique for treatment of radiculopathy due to cervical disc herniation in a carefully selected subgroup of patients with good medium- to long-term outcomes. A larger study would possibly highlight the effectiveness of this procedure.

Introduction: Minimally Invasive Transforaminal Lumbar Interbody Fusion (MIS-TLIF) has been shown to offer several advantages over conventional (open) TLIF and is being increasingly employed by young surgeons early in their careers. It is important to know the appropriate technique and the correct cases to be selected in the early phase to achieve good outcomes during the learning curve. A detailed and illustrative technical note along with a guide for case selection at different phases of experience has been presented in this article. Methods: The first consecutive single surgeon series of 150 MIS-TLIF cases done over 4 years between 2012 and 2015 were considered for analysis. Demographic and peri-operative data and previously documented follow-up were collected from case records. Telephonic questionnaire and consultation were done to collect latest status, any procedures/surgeries done elsewhere for issues related to index procedure. Results were stratified as Group 1 – first 25 cases; Group 2 – 26–75 cases; Group 3 – 76–150 cases. Results: The major indication for surgery in group 1 was either Grade 1 spondylolisthesis or lumbar canal stenosis with concomitant axial symptoms. The incidence of relatively complex cases (Grade 2 or 3 listhesis; Revision cases; Multilevel cases) increased with each successive group. As expected, the operative time (calculated for only single-level cases) improved with time. The overall rate of peri-operative complications was higher in group 2 as compared to groups 1 and 3, predominantly due to an increased incidence of intra-operative dural tears in group 2. Symptomatic screw malposition was detected in five screws, all were managed conservatively. The median duration of follow-up for the entire group was 39 months (Range – 1–119 months). Eighty-two (55%) patients had follow-up of more than 1 year while 31 (20.6%) patients had follow-up of more than 7 years. Around 80–85% of patients at each point of follow-up assessment had a successful outcome (McNab 4 and 5). The re-operation rate for index level problems or adjacent segment was 2.6%, only one of which was done at the author’s center. Conclusions: Minimally invasive TLIF is a safe and effective procedure with favorable long-term results and acceptable complication rates. Though technically challenging in initial phases, a good understanding of the technique and principles of minimally invasive spine surgery along with fulfilling helpful pre-requisites and appropriate case selection as mentioned in this article, will help to smoothen the learning curve and avoid unfavorable outcomes in early stages.

Conventional cervical pedicle screw insertion necessitates extensive paraspinal muscle dissection and retraction in order to achieve the lateral to medial angulation needed to achieve the optimal screw trajectory. Minimally invasive transmuscular approach can comfortably achieve this angulation without significant injury to the midline structures and its musculo-ligamentous attachments. Methods: Minimally invasive cervical pedicle screws were inserted in 4 fresh frozen cadaveric specimens. Pre-procedure and post-procedure CT scans were done to assess the pedicle dimensions, suitability for screw insertion and integrity of the screws. The same technique was applied in a clinical cohort of six cases -3 cases of traumatic subluxation; one case of traumatic vertebral fracture and 2 cases of infective facet destruction (Koch's). Results: Among the 38 screws in the cadaver specimens, a total of 11 screws (28.9%) had breached the pedicle wall(Lateral wall breach-9; Medial wall breach-2). Of the 9 screws (23.6%) that had a lateral breach into the vertebral canal, 4 (10.5%) each had Grade IIa breach and one (2.6%) had Grade III breach. Among the 22 screws inserted in the clinical cohort of 6 cases, 4 screws (18.1%) had breached the pedicle wall. All the identified breaches were in the lateral wall(Grade IIa -3; Grade IIb-1; Grade III-nil). Conclusion: Minimally invasive subaxial pedicle screw insertion provides robust posterior cervical fixation, either in isolation or as an adjunct to anterior surgery, in cases where a direct posterior decompression is not warranted. It is a safe and effective approach which minimizes injury to the paraspinal structures and midline attachments.

There have been several reports of minimally invasive decompression for cervical canal stenosis and degenerative myelopathy. Most of these reports are for less than 4 levels and there have not been any comparative studies between Open and MIS cervical decompression for multilevel ( ≥ 4) degenerative cervical myelopathy. Methods: Twenty consecutive patients were allotted to undergo either 'Open' cervical laminectomy (n = 10) or MIS posterior cervical decompression (n = 10). All patients were evaluated for 1. Clinical, (JOA, MDI, NDI, Nurick grade, Blood loss, Duration of surgery); 2. Radiological (CSA of dural sac and Spinal cord, Muscle edema on post-op T2W MRI); 3. Laboratory (TLC, CRP, ESR, CPK) and 4. Physical (Isometric neck extensor muscle strength). Differences between Open and MIS groups were calculated with respect to above parameters. Results: The mean number of levels decompressed was 4.4 (range, 4-6). MIS group had significantly longer duration of surgery and lesser blood loss as compared to open group. The patients in open group were more disabled than MIS group pre-operatively, as evidenced by higher MDI and NDI. However, proportionate improvements were seen in both groups post-operatively in terms of all clinical parameters. Postoperative increase in CSA of spinal cord was also identical in both groups. Elevations in CRP and ESR were significantly higher in Open group post-operatively as compared to MIS group. Post-operative extensor neck muscle strength improved to a higher extent in MIS group as compared to open group though this was not statistically significant. No patient had any major post-operative complications. Conclusion: MIS posterior cervical decompression is safe and effective, can achieve similar extent of decompression and degree of clinical improvement as compared to open surgery. MIS has definite advantages of lesser blood loss, reduced tissue injury and better improvement in post-operative neck muscle strength as compared to open surgery.