Conventional vs. endoscopic-assisted curettage of benign bone tumours. An experimental study

Abstract

Background: This experimental study aimed at directly comparing conventional and endoscopic-assisted curettage towards (1) amount of residual tumour tissue (RTT) and (2) differences between techniques regarding surgical time and surgeons' experience level.

Methods: Three orthopaedic surgeons (trainee, consultant, senior consultant) performed both conventional (4x each) and endoscopic-assisted curettages (4x each) on specifically prepared cortical-soft cancellous femur and tibia sawbone models. "Tumours" consisted of radio-opaque polyurethane-based foam injected into prepared holes. Pre- and postinterventional CT-scans were carried out and RTT assessed on CT-scans. For statistical analyses, percentage of RTT in relation to total lesion's volume was used. T-tests, Wilcoxon rank-sum tests, and Kruskal-Wallis tests were applied to assess differences between surgeons and surgical techniques regarding RTT and timing.

Results: Median overall RTT was 1% (IQR 1 - 4%). Endoscopic-assisted curettage was associated with lower amount of RTT (median, 1%, IQR 0 - 5%) compared to conventional curettage (median, 4%, IQR 0 - 15%, p = 0.024). Mean surgical time was prolonged with endoscopic-assisted (9.2 ± 2.9 min) versus conventional curettage (5.9 ± 2.0 min; p = 0.004). No significant difference in RTT amount (p = 0.571) or curetting time (p = 0.251) depending on surgeons' experience level was found.

Conclusions: Endoscopic-assisted curettage appears superior to conventional curettage regarding complete tissue removal, yet at expenses of prolonged curetting time. In clinical practice, this procedure may be reserved for cases at high risk of recurrence (e.g. anatomy, histology).

Keywords: Benign bone tumour; Curettage; Endoscopy; Orthopaedic oncology.

Fig. 1

Graphical visualisation of the study workflow. Tumour cavities were prepared at the proximal and distal metaphyses of six femoral and tibial sawbones. Subsequently, CT-scans of the prepared sawbones were carried out. Thereafter, each surgeon performed curettages on two femoral and two tibial sawbones, once with the conventional (green) and once with the endoscopic-assisted technique (orange). Following intervention, all sawbones again underwent CT-scans. Ultimately, image analysis of pre- and postinterventional CT-scans was carried out

Fig. 2

Experimental built-up. (Top) Picture of the experimental built-up showing endoscope (left), prepared femoral and tibial sawbone (middle) and curettes used (right). (Bottom, left) Pre-interventional CT scan of a proximal femoral sawbone in 3 planes (coronal, sagittal, axial) depicting the cement restrictor to seal the medullary canal and the contrast-enhanced foam used to mimic the lesion. (Bottom, right) CT-scan in 3 planes (coronal, sagittal, axial) of the same proximal femoral sawbone following curettage, with contrast-enhanced foam still visible at the lesion’s periphery. Orange lines define segments used for radiological assessment of RTT.

Fig. 3

Overall percental residual tumour tissue (RTT) as well as RTT per segment analysed, separated by surgical technique. Green and blue bars show median percental RTT per segment with 25th and 75th percentile, and orange bars the sum of RTTs within each segment with 25th and 75th percentile. Whiskers denote lower and upper adjacent values*. P-value based on Wilcoxon rank-sum test. *adjacent values defined as 25th or 75th percentile + 1.5 x interquartile range

Fig. 4

Difference in curetting time between surgeons depending on technique. Bars depict median curetting time with 25th and 75th percentile. Whiskers denote lower and upper adjacent values*. P-values based on Kruskal-Wallis test. *adjacent values defined as 25th or 75th percentile + 1.5 x interquartile range