Sometimes the findings of well-designed orthopaedic studies are unexpected and counterintuitive—and sometimes they are not. In the latter category are the important but unsurprising results from the Grace et al. database study in the February 19, 2020 issue of The Journal of Bone & Joint Surgery.
The authors set out to determine whether having a specific medical complication after a first total knee arthroplasty (TKA) increased the chance that the same complication would occur after a second TKA performed 90 to 365 days after the first one. Among the specific complications investigated were myocardial infarction (MI), ischemic stroke, respiratory complications, urinary complications, digestive complications, hematoma, deep vein thrombosis (DVT), and pulmonary embolism (PE).
Overall complications after either procedure were low—>90% of the >36,200 patients who underwent bilateral TKAs did not experience any complications during the study period. However, those who had a complication after the first TKA had a significantly higher likelihood of having the same complication after the subsequent, contralateral procedure. Expressed as odds ratios (ORs), the increased probabilities of the same complication recurring after the second procedure were as follows:
- Myocardial infarction—OR, 56.63
- Ischemic stroke—OR, 41.38
- Hematoma—OR, 15.05
- Urinary complications—OR, 11.19
- PE—OR, 11.00
- Respiratory complications—OR, 8.58
- Non-MI cardiac complications—OR, 7.73
- DVT—OR, 7.40
Noting that these findings do not imply causality, the authors nevertheless surmise that “the occurrence of complications after the first replacement likely reflects a burden of comorbidity that predisposes patients to a recurrence of the same complications after the second replacement.” Consequently, Grace et al. suggest that this data could be used to help guide shared decision-making with patients considering staged bilateral TKAs, and that these findings could help identify “a subgroup of patients who may benefit from…targeted optimization strategies prior to the second surgical procedure.”