OBJECTIVES: The objective of this analysis was to compare the direct medial costs between patients who received intra-articular hyaluronic acid (HA) injections prior to total knee replacement (TKR) and patients who did not receive HA injections prior to TKR.

METHODS: A previous study of 22,555 TKR patients using a commercial claims database showed that the time from diagnosis of knee osteoarthritis to TKR surgery was a median of 1.6 years longer for patients receiving HA injections compared to patients not receiving HA injections (p<0.0001) over an 8 year continuous enrollment period. HA patients received an average of 1.7 HA injections over the study period. The number of HA injections and TKR survival curves from this publication were used to quantify the predicted medical costs for hypothetical cohorts of HA (n=500) and non-HA patients (n=500) in an economic model. Direct costs of TKR and HA injections were estimated from the literature and costing algorithms. An annual discount rate of 3% was applied.

RESULTS: Cumulative costs over 4 years totaled $11.3 million and $12.7 million in the HA cohort and non-HA cohort, respectively. Costs in the HA cohort were $1.4 million lower than the non-HA cohort over 4 years due to the delay in TKR. The cohorts reached cost-equivalence at 8 years as 98.1% of the HA cohort and 99.1% of the non-HA cohort received a TKR. Costs for HA injections were <4% of total cost in the HA cohort. Results were most sensitive to number of HA series received and least sensitive to changes in HA cost and discount rate. Results are not generalizable to those over age 65 as those patients were not included in the original claims analysis.

CONCLUSIONS: A cost savings of $1.4 million may be achieved from delaying TKR with HA injections over a 4-year period.