gms | German Medical Science

Objective: Degenerative spondylolisthesis is an acquired condition with intersegmental instability of one or more lumbar motion segments. Ultimately, this results in spinal canal stenosis, causing a variety of neurological symptoms. Many surgical techniques are currently used for treatment, with fusion of the affected segment being the goal. The recent trend has been to establish less invasive procedures in order to reduce soft tissue and bone damage. HybridLIF provides a novel minimally invasive technique for navigated monosegmental lumbar decompression, realignement and interbody fusion.

Method: We report about 6 patients with single-level lumbar degenerative spondylolisthesis that underwent lumbar stabilization with our new technique. HybridLIF uses a standard unilateral midline approach for decompression and contralateral undercutting. After ipsilateral partial arthrectomy the same approach is employed to implant a specially designed cage, made of an anterior and posterior element linked with a joint (SYNCHRO^®; Arca-Medica, Neuenburg, Germany). Pedicle screws are placed using navigation. While contralateral screws are set in conventional percutaneous coaxial (dorsolateral) fashion, a different, vertical (dorsoventral) vector serves for ipsilateral pedicle screw placement. As a result, the ipsilateral pedicle screws can be inserted through the established unilateral dorsal midline approach. This reduces skin incisions and soft tissue damage. Surgery results were documented by a lumbar CT-scan. Patient and operative data, VAS pain scores (back, leg) and COMI were collected preoperatively as well as at 6 weeks, 3 month and 6 month after surgery.

Results: Average blood loss was 450ml. Postoperative CT-scan showed correct implant placement in all but one case. For this patient pedicle screw revision was necessary. There was significant postoperative improvement of VAS (leg) scores at 3 and 6 month (p<0,05). COMI improved significantly at 6 week as well as at 6 month follow-up (p<0,05).

Conclusions: HybridLIF allows decompression as well as reliable realignment and interbody fusion for patients with monosegmental degenerative spondylolisthesis. Compared to standard procedures, HybridLIF is associated with a considerable reduction of soft-tissue and paraspinal muscle injury as well as shorter overall skin incisions. Intraoperative navigation will contribute to elevate the surgeon’s learning curve. Long-term efficacy and safety are currently investigated with a larger number of patients.