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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.