BackgroundComputer-assisted navigation has made bone sarcoma resections more precise. However, further clinical studies involving accuracy analyses under navigation are still warranted.MethodsA 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.ResultsThe 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.ConclusionsBetter accuracy can be achieved when computer-assisted navigation is conducted for bone sarcoma resection around the knee.Level of evidenceIV.