Radiographic Changes in Nonoperative Contralateral Knee After Unilateral Total Knee Arthroplasty.

BACKGROUND: Some patients perceive symptomatic improvement in the contralateral knee after unilateral total knee arthroplasty (TKA). This so-called "splinting effect" has been observed but has not been radiographically evaluated.

METHODS: A retrospective review of patients with bilateral knee osteoarthritis treated with unilateral TKA was performed. Patients were subcategorized into 2 groups based on whether contralateral TKA was performed within the 2-year period. Contralateral radiographic measurements were performed.

RESULTS: Forty-four of 203 patients had contralateral TKA performed within 2 years. Preoperative parameters were significantly worse in the bilateral group. By 6 weeks postoperatively, mechanical axis plumbline improved approximately 1°, with more change in those patients with preoperative varus alignment. Larger delta changes were also present in bilateral group preoperative to 1-year radiographs for tibiofemoral angle and joint space widening.

CONCLUSION: In patients with bilateral knee osteoarthritis who undergo unilateral TKA, a splinting effect may be present and measurable radiographically with improvement of contralateral mechanical axis plumbline. Further research is necessary to determine whether this improvement may delay contralateral TKA implantation.