Lateral Lumbar Interbody Fusion: An Update on Motor Deficits in 1000 Patients Across Two Decades

Area of Science:

• Spine surgery
• Neurosurgery
• Orthopedic surgery

Background:

• Lateral lumbar interbody fusion (LLIF) is a minimally invasive surgical technique.
• Approach-related motor deficits, particularly affecting the iliopsoas and quadriceps muscles, are known complications of LLIF.
• Updated data on the incidence and risk factors for these deficits are crucial for surgical decision-making and patient counseling.

Purpose of the Study:

• To determine the current rates of approach-related postoperative motor deficits following standalone LLIF.
• To identify independent risk factors associated with the development of these motor deficits.
• To compare motor deficit rates between two distinct decades of LLIF procedures.

Main Methods:

• Retrospective cohort study analyzing 1000 standalone LLIF procedures performed between 2006 and 2024.
• Procedures were divided into two decades: 2006-2015 (n=395) and 2016-2024 (n=605).
• Iliopsoas and quadriceps motor strength (MRC grades) were assessed preoperatively and at multiple postoperative time points (discharge, 6 weeks, 3 months, 6 months, 1 year, last follow-up).

Main Results:

• The incidence of ≥1 MRC grade iliopsoas deficits at 6 weeks decreased from 12.7% in the first decade to 4.1% in the second decade (P < 0.001).
• Quadriceps deficits at 6 weeks decreased from 5.3% to 1.7% (P = 0.002) over the same period.
• Persistent weakness at 6 months/1 year was rare (≤0.8%), with only one patient experiencing residual quadriceps weakness at 2 years.

Conclusions:

• Postoperative motor deficits following standalone LLIF have significantly improved over the last decade.
• Surgery at the L4/5 level and increased operative time remain significant risk factors for motor deficits.
• Despite identified risk factors, the majority of motor deficits are transient, supporting the safety of LLIF in appropriately selected patients.