Aseptic tibial debonding as a cause of early failure in a modern total knee arthroplasty design

Abstract

Background: We observed isolated tibial component debonding from the cement in one modern primary TKA design (NexGen LPS 3° tibial tray; Zimmer, Warsaw, IN, USA). This failure mechanism is sparsely reported in the literature.

Questions/purposes: We (1) assessed survivorship of this tibial tray with special emphasis on debonding; (2) described clinical and radiographic features associated with tibial failure; and (3) compared patient and radiographic features of the failures with a matched cohort.

Methods: A total of 1337 primary TKAs were performed with a cemented NexGen LPS 3° tibial tray over an 11-year period. Twenty-five knees (1.9%) were revised for tibial debonding. BMI and radiographic alignment in the tibial debonding group were compared with a matched control group. Implant survivorship was assessed using tibial debonding as the end point.

Results: Survival free of revision from tibial debonding was 100% at 1 year and 97.8% at 5 years. The tibial failures shared a typical radiographic pattern with debonding at the cement-implant interface and subsidence into varus and flexion. We found no link between limb alignment or individual component alignment and failure because 22 of the 25 failures occurred in well-aligned knees.

Conclusions: Our standardized followup of patients undergoing TKA at routine intervals allowed us to discover a higher rate of revision resulting from tibial debonding. We have discontinued the use of this particular tibial tray for primary TKA and surveillance for patients undergoing TKA continues to be warranted.

Fig. 1A–B

(A) NexGen 3° Fluted Stem Tibial Plate (Option) and (B) NexGen LPS femoral option. This design can be used with a stem extension and augments if needed.

Fig. 2

Reason for failure within the 57 primary TKAs with isolated tibial debonding being the most common cause.

Fig. 3

Kaplan-Meier survivorship with revisions resulting from any reason as the end point (CI = Confidence Interval).

Fig. 4

Kaplan-Meier survivorship with revisions resulting from aseptic tibial debonding as the end point (CI = Confidence Interval).

Fig. 5A–B

The AP view (A) reveals a pronounced varus position of the tibial tray. The lateral view (B) demonstrates flexion subsidence with debonding at the cement-prosthesis interface.

Fig. 6A–D

(A) Anterior and (B) posterior radiographs of a patient with an asymptomatic TKA at 24 month postoperatively. There are radiolucent lines present underneath the tibial tray. (C-D) Nine months later the patient presents with radiographs showing debonding of the tibial component.

Fig. 7

Debonding of the tibial component leaves behind a nearly intact cement mantle attached to the proximal tibia.