Intraoperative and Postoperative Segmental Lordosis Mismatch: Analysis of 3 Fusion Techniques

This study aimed to quantify the discrepancy between intraoperative and postoperative segmental lordosis in patients operated on for lumbar degenerative diseases, with 3 different fixation techniques: open posterolateral instrumentation alone (PLI) or in association with lumbar interbody cages (transforaminal lumbar interbody fusion [TLIF] or extreme lateral interbody fusion [XLIF]).

We retrospectively reviewed all adult patients affected by single-segment degenerative spondylotic disease who underwent PLI alone or percutaneous posterolateral instrumentation (pPLI) in association with TLIF or XLIF between April 2015 and December 2017 at our institution. Group I included patients who underwent PLI with transpedicular screws and rods, interlaminar bilateral decompression, and posterolateral fusion with autologous bone chips. Group II included patients treated with pPLI + TLIF using a complete unilateral arthrectomy. Group III included patients operated on with minimally invasive retroperitoneal pPLI + XLIF.

No major complications were reported. The mean segmental loss of lordosis values ranged from 9.17% to 12.28% in Group I, from 6.31%-9.43% in Group II, and from 3.05%-4.71% in Group III. The statistical analysis revealed that pPLI + XLIF maintained a higher segmental lordosis than PLI and pPLI +TLIF in each operated segment (P < 0.05). pPLI + TLIF was more effective than PLI in reducing the loss of lordosis at L4-L5 and at L5-S1 (P < 0.05) but not at L3-L4 (P = 0.12).

The documented mismatch between the preoperative and postoperative lumbar lordosis might affect the clinical outcome. Its relevance depends on the surgical technique used at the single level.