Direct Tubular Lumbar Microdiscectomy for Far Lateral Disc Herniation: A Modified Approach

Objective: The concept of minimally invasive tubular discectomy is based on precise placement of the retractor over the surgical target to minimize collateral tissue trauma. For far lateral disc herniation, the junction between the pars and the transverse process has generally been adopted as the target for facilitating early nerve root exposure; however, this may limit access to the disc space and increase the risks of iatrogenic neuralgia. An alternative approach to help address these issues involving docking the retractor caudally directly over the disc space with the aid of a microscope is here proposed. The purpose of this study was to evaluate the safety and efficacy of such an approach.

Methods: Nineteen patients in whom the modified approach was performed over a 35-month period were identified. Direct access to the disc space was attained by directing the retractor against the lateral margin of the facet joint and following the inferior transverse process medially towards the foramen with minimal exposure of the nerve root. Clinical outcomes were assessed by the Oswestry Disability Index, visual analogue scale scores for leg and back pain, Short Form 36 physical functioning (SF36-PF) and bodily pain (SF36-BP) scores and sciatica bothersomeness and frequency indexes (SBI & SFI) and obtained from a prospective patient database. Follow-up data in the first 6 months were compared with preoperative baseline data.

Results: All procedures were successfully completed with the modified approach. Contained disc herniation without sequestrated fragments was found in all but four cases. No perioperative complications or reoperation were recorded and no postoperative dysesthesia was noted. Clinically significant reductions in mean Oswestry Disability Index (32; 95% CI, 21-43) and visual analogue scale scores for leg pain (38 mm; 95% CI, 23-54 mm) and back pain (35 mm; 95% CI, 21-48 mm) scores were noted in the first 6 months. Significant improvements in SF36-PF (40; 95% CI, 30-51) and SF36-BP (35; 95% CI, 26-43), SBI (9; 95% CI, 6-11) and SFI (11; 95% CI, 8-13) were also recorded.

Conclusions: A modified direct tubular approach is safe and effective for treating far lateral lumbar disc herniation. Our early results suggest that this approach helps safeguard adequate decompression and reduce the risk of postoperative dysesthesia.