One-stage combined lumbo-sacral fusion, by anterior then posterior approach: clinical and radiological results

Abstract

Introduction: We intended to prospectively evaluate the clinical and radiological results of lumbo-sacral fusion achieved by a combined approach, anterior then posterior.

Material and methods: 62 patients were consecutively treated at L5-S1, L4-L5 or L4-S1 for degenerative disc disease or low-grade isthmic spondylolisthesis by combined surgery.

Results: Mean operative time and blood loss were 209 min and 308 ml, respectively, including the two approaches. VAS, ODI and Roland-Morris scores significantly improved postoperatively at 1 year (p < 0.005) and fusion was obtained in all cases on the CT scan at 1-year follow-up. Segmental lordosis significantly improved postoperatively (p < 0.05) with a mean gain of 10.2° at L5-S1 and 5.5° at L4-L5.

Conclusion: The combined procedure meets the requested criteria for a lumbar fusion in terms of clinical results, functional outcomes, fusion rates while restoring segmental lordosis and disc height. It cumulates the advantages of the anterior and posterior approach performed alone, especially for L5-S1.

Fig. 1

Oblique, posterior and lateral views of the construct demonstrating anterior interbody PEEK cage associated with pedicle screw-based posterior stabilization

Fig. 2

Distribution of levels fused

Fig. 3

C7 plumbline/sacro-femoral distance ratio defined as the ratio between the distance separating C7PL from the postero-superior corner of the sacrum and the sacro-femoral distance (i.e., SFD, the horizontal distance between the vertical bi-coxo-femoral axis and the vertical line passing through S1 endplate posterior corner). C7/SFD evaluates the global sagittal alignment of the spine above the pelvis (normal value −0.9 ± 1), [11]

Fig. 4

Grade II isthmic spondylolisthesis treated by combined approach, anterior then posterior. Segmental lordosis significantly increased postoperatively at the index level while nearly complete reduction of slipping was obtained

Fig. 5

Low-grade L5–S1 isthmic spondylolisthesis. Combined approach allows obtaining a 360° intervertebral fusion with a large interbody and postero-median (i.e., interlaminar and interfacet) bone mass fusion

Fig. 6

Advantages of the AP sequence are: realignment of the spine and restoration of disc height during the anterior step (ANT) facilitated by the patient placed in supine position and the lumbar spine slightly in extension, and then, optimal stabilization during the posterior stage (POST), with the patient in prone position, by pedicle screw-based fixation

Fig. 7

The amount of lordosis restored was adapted to the spino-pelvic parameters. This is the case of a woman with a high PI (more than 60°), theoretical lumbar lordosis was estimated to 70° meaning that L5–S1 segment required between 25° and 30° of lordosis (corresponding to 40 % of the global lordosis). The need to restore 25-30° at L5-S1 could be achieved using the combined approach

Fig. 8

Comparison of interbody cages usually implanted during posterior technique (PLIF, 10° of lordosis and 10 mm of height) versus anterior approach (ALIF, 13°/13 mm). This underlies the advantages of the combined approach in terms of lordosis and disc height restoration and bone graft volume