Maintenance of segmental lordosis and disk height in stand-alone and instrumented extreme lateral interbody fusion (XLIF)

STUDY DESIGN: Prospective single surgeon non-randomized clinical study.

OBJECTIVE: To evaluate radiographic and clinical outcomes, by fixation type, in extreme lateral interbody fusion (XLIF) patients and provide an algorithm for determining patients suitable for standalone XLIF.

SUMMARY OF BACKGROUND DATA: XLIF may be supplemented with pedicle screw fixation, however, since stabilizing structures remain intact, it is suggested that standalone XLIF can be used for certain indications. This eliminates the associated morbidity, though subsidence rates may be elevated, potentially minimizing the clinical benefits.

METHODS: A fixation algorithm was developed after evaluation of patient outcomes from the surgeon's first 30 cases. This algorithm was used prospectively for 40 subsequent patients to determine requirement for supplemental fixation. Preoperative, postoperative and 12 month follow-up computed tomography (CT) scans were measured for segmental and global lumbar lordosis and posterior disc height. Clinical outcome measures included back and leg pain (visual analogue scale), Oswestry Disability Index (ODI), and SF-36 physical and mental component scores (PCS and MCS).

RESULTS: Preoperatively to 12 month follow-up there were increases in segmental lordosis (7.9° to 9.4, P=0.0497), lumbar lordosis (48.8° to 55.2°, P=0.0328) and disc height (3.7 mm to 5.5 mm, P=0.0018); there were also improvements in back (58.6%) and leg pain (60.0%), ODI (44.4%), PCS (56.7%) and MCS (16.1%) for standalone XLIF. For instrumented XLIF, segmental lordosis (7.6° to 10.5°, P=0.0120) and disc height (3.5 mm to 5.6 mm, P<0.001) increased, whilst lumbar lordosis decreased (51.1° to 45.8°, P=0.2560). Back (49.8%) and leg pain (30.8%), ODI (32.3%), PCS (37.4%) and MCS (2.0%) were all improved. Subsidence occurred in 3 (7.5%) standalone patients.

CONCLUSION: The XLIF treatment fixation algorithm provided a clinical pathway to select suitable patients for standalone XLIF. These patients achieved positive clinical outcomes, satisfactory fusion rates, with sustained correction of lordosis and restoration of disc height.