High incidence of radiolucent lines at the implant-cement interface of a new total knee replacement.

BACKGROUND: Recently introduced total knee arthroplasty (TKA) implants have been linked with the early development of periprosthetic radiolucency (PPRL). The aim of this study was to carry out a retrospective clinical and radiographical analysis of a consecutive series of a new TKA, and to assess the incidence and distribution of PPRL. METHODS: A retrospective review of all new TKA implants performed by a single surgeon at a single hospital between March 2013 and October 2017 was performed. The minimum follow-up period was 3 months, with ongoing patient review at 6, 12 and 36 months. Sequential post-operative radiographs were performed to determine the presence of PPRL. RESULTS: A total of 122 TKAs were identified in 112 patients over the 4.5-year study period. The average follow-up time was 21 months (range 3-51 months). PPRL was noted in 29 TKAs (23.8%). When comparing the PPRL group to those without PPRL, there was a difference in body mass index, with body mass index associated with an increased likelihood of PPRL (P = 0.003). There was no difference in constraint of implant (P = 0.818), cement type (P = 0.340), patella resurfacing (P = 0.286), age (P = 0.984) gender (P = 0.376) or initial mechanical axis deviation (P = 0.054) between groups. PPRL were most commonly seen in tibial anterior-posterior (AP) zone 1 and zone 2 (96.6%), followed by femoral lateral zone 5 (58.6%), tibia lateral zone 1 (55.2%) and tibial lateral zone 2 (53.2%). No patients have required revision surgery. CONCLUSION: A high incidence of early PPRL is seen in patients undergoing primary TKA using a new implant system, mainly involving the tibial component. Ongoing clinical and radiological assessment for patients seems warranted based on these findings.