And our assumption going into the process was that VBP would pose no more than a 1% risk in terms of impact to ZB's overall revenue.
We do believe that sizing this at around 1% of revenue impact is still accurate, that is the right way to size it.
Net sales in the third quarter were $1.924 billion, a reported decrease of 0.3% and a decrease of 0.8% on a constant currency basis.
When compared to 2019, net sales increased 0.4%.
The Americas declined 3.2% or flat versus 2019.
The U.S. declined 4.4% or up 0.1% versus 2019.
EMEA grew 5.9% or up 0.3% versus 2019.
Lastly, Asia Pacific grew 0.5% or up 1.5% versus 2019.
The global knee business declined 0.7% or down 1% versus 2019.
In the U.S., knee is declined 5.3% or down 0.7% versus '19.
Our global hip business declined 6.6% or down 2.4% versus 2019.
In the U.S., hips declined 11.3% or down 2.4% versus '19.
The sports extremity and trauma category increased 4.2% or 7.7% versus '19, driven by continuing commercial specialization, new product introductions and the contribution from strategic acquisitions we added to this portfolio in 2020.
Our dental and spine category declined 6.1% or down 2% versus 2019.
Finally, our other category grew 15.4% or down 1.1% versus 2019.
For the quarter, we reported GAAP diluted earnings per share of $0.69, lower than our GAAP diluted earnings per share of $1.16 in the third quarter of 2020.
On an adjusted basis, diluted earnings per share of $1.81 was flat compared to the prior year, even though sales were down.
Adjusted gross margin of 70.3% was just below the prior year, and the results were slightly below our expectations due to lower volumes in tandem with less favorable product and geographic mix.
Our adjusted operating expenses of $852 million were in line with the prior year and stepped down sequentially versus the second quarter.
Our adjusted operating margin for the quarter was 26.1%, largely in line with the prior year and prior quarter.
The adjusted tax rate of 15.8% in the quarter was in line with our expectations.
We had operating cash flows of $433 million and free cash flow totaled $307 million with an ending cash and cash equivalents balance of just over $900 million.
We continue to make good progress on deleveraging the balance sheet and pay down another $300 million of debt totaling $500 million of debt paydown for 2021 to date.
As a result, our current projection for Q4 VBP impact is about 300 basis points of headwind to our consolidated results, but the situation remains fluid, and we will continue to update you as the implementation of VBP unfolds.
For the full year, we now expect reported revenue growth to be 11.3% to 12.5% versus 2020 with an FX impact of about 140 basis points of tailwind for the year.
While we are taking steps to further reduce spending in the fourth quarter as a response to our lower revenue outlook, we are reducing our adjusted operating margin projections to be 26% to 26.5% for the full year.
Our updated full year adjusted diluted earnings per share guidance is now in the range of $7.32 to $7.47.
Our adjusted tax rate projection is unchanged at 16% to 16.5%.
And finally, our free cash flow estimates remain in the range of $900 million to $1.1 billion.
This updated full year 2021 guidance range implies that Q4 constant currency revenue growth will be between negative 2.3% and positive 1.8% versus Q4 2020.
And we project Q4 adjusted earnings per share to be between $1.90 to $2.05.
Additionally, as we mentioned earlier, VBP is expected to reduce 2022 consolidated revenues by about 100 basis points.
We're going to enter 2022 with a new product pipeline of more than 20 anticipated product launches across the next two years.
All of this forward momentum plus ZB's differentiated portfolio, the expected value creation of our planned spin transaction and our ability to execute really does give us continued confidence in our path to grow revenue in the mid-single digits and to deliver a 30% operating margin by the end of 2023.

Summary:
Net sales in the third quarter were $1.924 billion, a reported decrease of 0.3% and a decrease of 0.8% on a constant currency basis.
For the quarter, we reported GAAP diluted earnings per share of $0.69, lower than our GAAP diluted earnings per share of $1.16 in the third quarter of 2020.
On an adjusted basis, diluted earnings per share of $1.81 was flat compared to the prior year, even though sales were down.
Our updated full year adjusted diluted earnings per share guidance is now in the range of $7.32 to $7.47.