The accuracy of free hand resection in limb salvage surgery of bone tumours

Fluoroscopically calibrated 3D-printed patient-specific instruments improve the accuracy of osteotomy during bone tumor resection adjacent to joints

BACKGROUND

Inadequate surface matching, variation in the guide design, and soft tissue on the skeletal surface may make it difficult to accurately place the 3D-printed patient-specific instrument (PSI) exactly to the designated site, leading to decreased accuracy, or even errors. Consequently, we developed a novel 3D-printed PSI with fluoroscopy-guided positioning markers to enhance the accuracy of osteotomies in joint-preserving surgery. The current study was to compare whether the fluoroscopically calibrated PSI (FCPSI) can achieve better accuracy compared with freehand resection and conventional PSI (CPSI) resection.

METHODS

Simulated joint-preserving surgery was conducted using nine synthetic left knee bone models. Osteotomies adjacent to the knee joint were designed to evaluate the accuracy at the epiphysis side. The experiment was divided into three groups: free-hand, conventional PSI (CPSI), and fluoroscopically Calibrated PSI (FCPSI). Post-resection CT scans were quantitatively analyzed. Analysis of variance (ANOVA) was used.

RESULT

FCPSI improved the resection accuracy significantly. The mean location accuracy is 2.66 mm for FCPSI compared to 6.36 mm (P < 0.001) for freehand resection and 4.58 mm (P = 0.012) for CPSI. The mean average distance is 1.27 mm compared to 2.99 mm (p < 0.001) and 2.11 mm (p = 0.049). The mean absolute angle is 2.16° compared to 8.50° (p < 0.001) and 5.54° (p = 0.021). The mean depth angle is 1.41° compared to 8.10° (p < 0.001) and 5.32° (p = 0.012). However, there were no significant differences in the front angle compared to the freehand resection group (P = 0.055) and CPSI (P = 0.599) group. The location accuracy observed with FCPSI was maintained at 4 mm, while CPSI and freehand resection exhibited a maximum deviation of 8 mm.

CONCLUSION

The fluoroscopically calibrated 3D-printed patient-specific instruments improve the accuracy of osteotomy during bone tumor resection adjacent to joint joints compared to conventional PSI and freehand resection. In conclusion, this novel 3D-printed PSI offers significant accuracy improvement in joint preserving surgery with a minimal increase in time and design costs.

Accuracy of bony resection under computer-assisted navigation for bone sarcomas around the knee

BACKGROUND

Computer-assisted navigation has made bone sarcoma resections more precise. However, further clinical studies involving accuracy analyses under navigation are still warranted.

METHODS

A retrospective study for analysis of computer-assisted navigation accuracy was carried out. Between September 2008 and November 2017, 39 cases of bone sarcomas around the knee joint were resected under computer-assisted navigation. The control group comprised 117 cases of bone sarcomas around the knee treated by limb salvage surgery wherein bony cutting was achieved freehand. The length difference (LD) was defined as the specimen length minus the planned resection length. The LDs were detected in both groups and compared. The margin accuracy (MA) was defined as the achieved margin minus the desired margin at the bone cutting site and was detected in the navigation group.

RESULTS

The LDs between the postoperative specimen length and the preoperative planned length were compared. In the navigation group, the LD was 0.5 ± 2.5 mm (range, - 5 to 5 mm), while in the freehand group, the LD was 3.4 ± 9.6 mm (range, - 20 to 29 mm), with a significant difference (P < 0.01). In the absolute value analysis, the LD absolute value was 2.0 ± 1.6 mm in the navigation group and 8.3 ± 6.0 mm in the freehand group, with a significant difference (P < 0.01). In the navigation group, the MA was 0.3 ± 1.5 mm (range, - 3 to 3 mm) and the MA absolute value was 1.1 ± 1.0 mm.

CONCLUSIONS

Better accuracy can be achieved when computer-assisted navigation is conducted for bone sarcoma resection around the knee.

LEVEL OF EVIDENCE

IV.

New perspectives on surgical accuracy analysis of image-guided bone tumour resection surgery

PURPOSE

Image-guided bone tumour resection surgery has been proved in previous literatures to be more accurate than those conventional freehand ones (p < 0.001). However, in this kind of surgery, there are still many procedures depending on manual operations, which will inevitably introduce surgical errors into the surgery. In particular, the negative surgical errors (i.e., errors toward tumour) would increase the risk of tumor recurrence and metastasis. Thus, the first purpose of this study was to evaluate whether the negative surgical errors of image-guided bone tumour resection surgery were statistically significantly great, the second purpose is to evaluate whether the negative surgical errors of image-guided long-bone tumour resection surgery were statistically equivalent to those of pelvis surgery, and the last purpose is to recommend a solution for suppressing these errors when using a navigation system.

METHODS

Negative surgical errors of 24 osteotomies in ten pelvis tumour resection operations and 16 osteotomies in ten long-bone surgeries under the image guidance of a navigation system were statistically evaluated and compared with - 2.0 mm. The equivalence of negative surgical errors of pelvis group and those of long-bone group was statistically tested. To suppress these negative surgical errors when using a navigation system, we recommend, based on the obtained statistics, to increase the margins between cut planes and tumour boundary during pre-operatively planning cut planes, by adding an extra margin with the empirical safe margin according to the absolute lower bound of 95% CI of negative surgical errors.

RESULTS

Negative surgical errors of the pelvis group and the long-bone group were both significantly less than - 2.0 mm (p < 0.001), but not statistically equivalent (Rg > 1 mm). 95% CI of negative surgical errors were from - 3.95 to - 3.27 mm for the pelvis group, and from - 2.69 to - 2.34 mm for the long-bone group. So, the extra margin added for image-guided pelvis tumour resection surgery should be set as 3.95 mm, and the extra margin added for image-guided long-bone surgery should be set as 2.69 mm.

CONCLUSION

The negative surgical errors of image-guided bone resection surgery were statistically significantly less than - 2.0 mm (p < 0.001), thus these errors cannot be safely ignored. Moreover, the negative surgical errors of the pelvis group were not equivalent to those of the long-bone group (Rg > 1.0 mm), thus the solution for image-guided pelvis tumour resection surgery and that for image-guided long-bone tumour resection surgery should be separately determined. In order to suppress these negative surgical errors when using a navigation system, we recommend to add extra 3.95 mm margin with the empirical safe margin for image-guided pelvis tumour resection surgery and to add extra 2.69 mm margin for image-guided long-bone tumour resection surgery during pre-operatively planning cut planes.

Resection margins obtained with patient-specific instruments for resecting primary pelvic bone sarcomas: A case-control study

BACKGROUND

Limb salvage surgery for pelvic bone sarcoma carries a very high risk of local recurrence. Patient-specific instruments (PSIs) have shown promise for obtaining tumour-free resection margins. However, no data are available on medium-term outcomes including local recurrence rates after PSI-guided resection. The objectives of this case-control study were to determine whether PSI-guided resection: 1) was associated with a lower local recurrence rate, 2) allowed a shorter operative time, 3) was associated with better-quality allograft reconstruction.

HYPOTHESIS

PSI-guided resection decreases the local recurrence rate by improving the resection margins in patients with primary pelvic bone sarcomas.

PATIENTS AND METHODS

PSI-guided resection was performed in 9 consecutive patients (cases) with primary pelvic sarcomas (chondrosarcoma, n=3; Ewing's sarcoma, n=3; osteosarcoma, n=1; fibrosarcoma, n=1; and radiation-induced sarcoma, n=1). Age ranged from 11 to 63 years. Outcomes were compared to those in a historical control group of 19 patients with primary bone sarcomas who underwent resection surgery in the same hospital without PSI guidance. The case and control groups were similar regarding age, sex distribution, and follow-up duration. The local recurrence rate and operative time were compared between the two groups. Resection margins were classified as R0, R1, or R2. The quality of allograft reconstruction, which was performed in 7 of the 9 cases, was assessed.

RESULTS

After a mean follow-up of 52 months (range, 30-90 months), none of the cases had experienced local bone or soft-tissue recurrences, compared to 7 of the 19 controls (p=0.03), in whom mean follow-up was 62 months (range, 24-134 months). Bone resection margins were R0 in 8 cases; in the remaining patient, R1 resection was performed deliberately to preserve an S1 root. All 9 cases had R0 soft-tissue resection margins. In the control group, bone resection margins were R0 in 13 patients, R1 in 5 patients, and R2 in 1 patient (p=0.47). Mean operative time was similar in the cases (612 minutes [range, 435-854 minutes]) and controls (633 minutes [range, 420-990 minutes]) (p=0.87). In the 7 patients who underwent pelvic allograft reconstruction, allograft contact in the defect and osteosynthesis stability were deemed satisfactory by the surgeon.

DISCUSSION

The lower local recurrence rate in the cases demonstrates that the improved resection accuracy provided by PSIs directly influences the risk of local recurrence. In addition, the R0 bone margins in 8 cases establishes that PSIs are effective in improving resection accuracy.

LEVEL OF EVIDENCE

III, case-control study.