Does repeat tibial tubercle osteotomy or intramedullary extension affect the union rate in revision total knee arthroplasty?

BACKGROUND AND PURPOSE Tibial tubercle osteotomy (TTO) is an established surgical technique for exposing the stiff kneein revision total knee arthroplasty (RTKA). The osteotomy is usually performed through the anterior metaphyseal cancellous bone of the tibia but it can be extended into the intramedullary canal if tibial stem and cement removal are necessary. Furthermore, repeat osteotomy may be required in another RTKA. We assessed whether intramedullary extension of TTO or repeat osteotomy affected the healing rate in RTKA. METHODS We retrospectively evaluated 74 consecutive patients (39 women) with an average age of 60 (29-89) years who underwent 87 TTOs during RTKA. 1 patient had bilateral TTO.10 patients had repeat TTO and 1 patient received 3 TTOs in the same knee. The osteotomy was extramedullary in 57 knees and intramedullary in 30 knees. Osteotomy repair was performed with bicortical screws and/or wires. RESULTS Bone healing occurred in all the cases. The median time to union was 15 (6-47) weeks. The median healing time for the extramedullary osteotomy group was 12 weeks and for the intramedullary osteotomy group it was 21 weeks (p = 0.002). Repeat osteotomy was not associated with delayed union. Neither intramedullary nor repeat osteotomy was found to increase the complication rate of the procedure. INTERPRETATION Reliable bone healing can be expected with intramedullary extension or repeat TTO in RTKA. However, intramedullary extension of the osteotomy prolongs the union time of the tibial tubercle.