[Assessment of agreement between anesthesiologists' location of anatomical landmarks]

A review of 571 radiographs on Tuffier's inter-cristal line and its' application in lumbar spinal surgery

BACKGROUND

Tuffier's line (TL) is an anatomical landmark used to identify the L4/5 interspace by palpating inter-cristal level in lumbar spinal surgery. The routine use of pre-operative pre-incision radiographs for level check by spinal surgeons is variable due to reliance on this palpation. The anatomical violation of neighbouring normal levels in microscope assisted lumbar surgery is unknown. The aim of this study was to evaluate the effects of patient-related demographic factors and radiographic parameters on TL in a cohort of patients undergoing lumbar spinal procedures.

METHODS

We retrospectively analysed 195 patients (571 radiographs) from a spinal database undergoing lumbar spinal procedures included nerve root injections, decompressions, micro-discectomies and instrumented fusions under a single surgeon. Radiographs were analysed with regard to age, gender, radiographic views (AP & lateral) and weight-bearing (wb) & non-weight bearing (non-wb).

RESULTS

The mean age was 59.8 years (range, 24-88 years). The most common level of TL was L4 vertebra (40% <60; 44% >60 years). The most common level in females was L5, while in males L4 vertebra. In 186 radiographs, 68% displayed a difference of at least one vertebral level on AP versus lateral planes. In 11 patients, there was at least 1 level vertebral difference between weight bearing & non-weight bearing radiographs.

CONCLUSIONS

TL can be affected by age, gender, radiographic views and weight bearing status variably. We recommend employing pre-incision radiographs in all microscope assisted lumbar spinal procedures to eliminate the clinical variations in inter-cristal line and thereby avoiding anatomical violation of neighbouring normal levels in microscope-assisted lumbar surgery. We highlight such variations in inter-cristal line should be given enough consideration in order to avoid a wrong level surgery. Palpatory method for level check without performing pre-incision lateral X-ray should be discouraged.

Abdominal circumference but not the degree of lumbar flexion affects the accuracy of lumbar interspace identification by Tuffier's line palpation method: an observational study

Background

Lumbar puncture for spinal or epidural anesthesia is commonly performed by palpating bony landmarks, but identification of the desired intervertebral level is often inaccurate. It is unclear whether such inaccuracy is related to patient factors, such as body mass index and degree of lumbar flexion. We hypothesized that overweight patients and patients with less of an ability to hyperflex their lumbar spines are prone to inaccurate lumbar spinous intervertebral level identification.

Methods

52 adult volunteers were included in this study. 7 anesthesiologists with different years of experience identified and marked subjects’ levels of the iliac crests, then marked the presumed interspaces. Lumbar X-ray was then performed with metal markers, and actual radiographic findings were identified and compared to the initial markings.

Results

Patients with larger abdominal circumferences (mean (SD), 94.0(12.1) cm), higher body mass indices (25.9(3.9) kg/m²), and aged between 50 and 70 years old had lumbar interspaces that were higher than the presumed level; patients with smaller abdominal circumferences (82.8(13.5) cm) and lower body mass indices (21.6(4.1) kg/m²) had intervertebral levels that were lower than the presumed level. Cobb’s angle, indicating the degree of lumbar flexion, did not affect the accuracy obtained.

Conclusions

Patients’ abdominal circumference, body mass index, and age are factors that may impact the accuracy of lumbar level identification. Tuffier’s line, as identified by palpation, does not seem to be a reliable landmark for proper lumbar interspace identification in all cases.