LARS® band and tube for extensor mechanism reconstructions in proximal tibial modular endoprostheses after bone tumors

Wide tumor resections around the proximal tibia (pT) are related to compromised function and high complication rates. This retrospective study aims to present the technique employed as well as functional and surgical outcomes of patients undergoing a Ligament Advanced Reinforcement System (LARS®) reconstruction of the knee extensor apparatus after tumor resection and modular endoprosthetic reconstruction of the proximal tibia.Twenty-five patients who received an artificial ligament after pT resection (11 men and 14 women; mean age, 29 years; range 11 to 75 years, with a minimum follow-up of 24 months) were analyzed regarding the ISOLS failure mode classification. Twenty patients received LARS® during primary surgery, five patients during a revision of a pT modular endoprosthesis. LARS® was available as a band or a tube.The mean extension lag was nine degrees (range, 0 to 30°), the mean flexion was 103° (range, 60 to 130°). The mean extension lag and active flexion in primary implanted LARS were 7.8° and 101° versus secondarily implanted 45° and 115° (p < 0.0001; p = 0.15). Eleven out of 14 primary implanted LARS® band/tubes (71%) did well with extension lag (0 to 10°). LARS® usage as a band or as a tube showed similar results. The estimated five-year survival of LARS® was 92%. The median survival of LARS® implanted primarily was better than in the case of secondary implantation (p = 0.006).Extensor mechanism reconstruction by LARS® band or tube shows excellent function and satisfactory implant survival after primary reconstruction of the extensor mechanism after proximal tibia resection. We experienced no LARS® rupture for only mechanical reasons.Level of evidenceLevel IV retrospective study.