One of the most important findings of this study was that the ABGS Cerasorb is associated with adequate and fast bone consolidation and long durability. Moreover, the complication rate is rather small. Also, a minimal invasive, percutaneous approach would be possible, as performed frequently for instance in case of vertebroplasty or kyphoplasty. In theory, according to the instructions for use, the resilience of Cerasorb is supposed to allow for an unrestricted postoperative mobilization protocol. In the authors’ opinion, more restricted postoperative protocols have to be applied, depending on the individual case, defect size and stability of the construct.
Complications associated with curettage and filling found in this study were due to a limited stability of the construct, leading to fractures when application was performed in a weightbearing bone, such as at the humeral diaphysis or the distal femur. In all cases, uncomplicated plate osteosynthesis was performed and healing was proper. However, little is known about stability and fractures after curettage and filling and thus, an important topic of future research will lie in the determination of stability properties of a tumor site, such as size and location, that necessitate the use of protective plate osteosynthesis in order to avoid the occurrence of fractures. Hirn et al.20 found a strong correlation between size and volume of the tumor and postoperative fracture occurrence. Kundu et al.21 proved that there was a correlation between size, volume and localization of the tumor and the risk of postoperative fracture. A retrospective case-series performed by Perisano et al.22 in 2016 focused on indications for prophylactic osteosynthesis associated with the curettage of benign and low-grade malignant bone tumors in the distal femur. They analyzed 12 patients treated by a single surgeon and recommended preventive osteosynthesis after curettage in case of very large lesions (> 5 cm, > 60 ccm) or high functional requirements, in obese patients and always, when local adjuvants such as ABGS were used. Moreover, studies showed that leaving the cavity unfilled involves an even higher risk of postoperative fracture and that the use of bone cement for filling yields the second highest fracture risk20,23,24.
In 2017, Friesenbichler et al.25 performed a prospective, non-randomized study on 27 patients treated with the α-TCP Calcibon (Biomet, Warsaw, IN) in granular form for filling bony cavity defects after curettage of benign or low-grade malignant bone tumors with an average postoperative follow-up of 26 months. Radiological consolidation was observed in 23 patients after a mean follow-up of six months. Nonetheless, resorption was not seen by that time or even after 32 months of follow-up. Moreover, no local recurrences occurred. The findings of this study were similar to those depicted in the present study, although with Cerasorb, complete resorption occurred in 16.3% of patients after a mean follow-up of 14.6 months. This is in line with current literature, as the ABGS Calcibon is similar to Cerasorb, but belongs to the group of α-TCPs, which are associated with a similar degree of solubility, but a slower biodegradation14.
In 2006, Hirata et al.26 analyzed 53 patients with benign bone tumors who had undergone curettage and filling with β-TCP. In their patient collective, complete resorption rates of the β-TCP were higher than in the present study, even though the follow-up time was comparable.
There were several limitations associated with the present study. First, data collection was performed retrospectively. Second, the mean follow-up period was only 14.6 months, which is quite a short interval, so that long-term effects and time to full resorption in those patients where resorption was not complete after the end of follow-up are missing. This shows that in order to capture the full resorption profile of the ABGS Cerasorb, a longer follow-up interval is definitely needed in future research. Third, the patient collective was rather small and heterogenous, as a lot of different tumor entities localized in different bones were included. Moreover, mostly due to the high heterogeneity of data, the analysis was purely descriptive and statistical analysis could not be performed.
In conclusion, based on our short-term observation, the β-TCP Cerasorb seems to be a reliable bone graft substitute with low complication rates and is a suitable alternative to autologous bone grafts or allografts. Nonetheless, it shows a tendency of delayed resorption.