Our fourth quarter organic sales declined to roughly 1%, reflecting the impact of a resurgence of COVID-19 infections offset by a continuation of emergent procedures and strong performance by our large capital products.
Throughout the quarter, we maintained the financial discipline instituted at the beginning of a pandemic which combined with a favorable tax rate, led to an adjusted earnings per share of $2.81 in the quarter, up approximately 13% versus 2019.
And we delivered impressive cash flow from operations which exceeded $3 billion for the full year.
This slowdown in elective procedures had a negative impact on our more deferrable businesses, which make up approximately 40% to 50% of our total sales.
During the year, our Mako install base grew by 33% and exceeded another milestone with over 100 robots sold and installed in the fourth quarter.
In the fourth quarter, approximately 44% of our total knees will make their knee procedures, a trend that continues to increase.
The shift toward cementless knees also continued and in the fourth quarter, cementless knees made up 42% of our U.S. knee procedures.
The combination of Stryker and Wright will continue to drive innovation that enhances our customers' ability to address patient needs across to more than $3 billion extremities market.
Our organic sales decline was 1.1% in the quarter.
Pricing in the quarter was unfavorable 0.8% from the prior year, while foreign currency had a favorable 1.2% impact on sales.
For the quarter, U.S. organic sales declined 1.5%, reflecting the slowdown in elective procedures as a result of the pandemic, somewhat offset by strong demand for Mako, medical products, and neurovascular products.
Organic sales decline for the year was 4.8%, with a U.S. decline of 5.8%, and an international decline of 2.1%.
2020 had one additional selling day compared to 2019 and for the year, price had an unfavorable 0.7% impact on sales.
Our adjusted quarterly earnings per share of $2.81 increased 12.9% from the prior year, reflecting strong financial discipline, good operating expense control, and a favorable operational tax rate.
Our fourth quarter earnings per share was positively impacted by $0.03 from foreign currency.
Our full-year earnings per share was $7.43, which is a decline of 10%, reflecting the impact of lower sales, especially in Q2, as well as the impact of idling certain manufacturing facilities during the year, offset by strong expense discipline throughout the year.
Orthopaedics had constant currency sales growth of 2.8% and an organic sales decline of 5.8%, including an organic decline of 5.7% in the U.S.
This reflects a slowdown in elective procedures related to COVID-19 and a very strong prior-year comparable as Q4 2019 U.S. organic growth was 7.2%.
Other ortho grew 12.3% in the U.S., primarily reflecting strong demand for our Mako robotic platform, partially offset by declines in bone cement.
Internationally, orthopaedics declined 6% organically, which also reflects the COVID-19 related to procedural slowdown, especially in Europe.
On a comparable basis for the full year, Wright had a 10.3% decline, mainly driven by the COVID-19 related slowdown in the second quarter.
In the quarter, MedSurg had constant currency growth of 1.5% and organic growth of 1.3%, which included 2.2% growth in the U.S. Instruments had U.S. organic sales growth of 4.5%.
Endoscopy had a U.S. organic sales decline of 7% primarily impacted by the slowdown in the capital businesses offset by gains in the sports medicine business, which grew over 9% in the quarter.
The medical division had U.S. organic growth of 9.7% reflecting solid performances in patient care, emergency care, and its Sage businesses.
Internationally, MedSurg had an organic sales decline of 2.4%, reflecting a general slowdown in instruments and endoscopy businesses and strong comparables across most geographies.
Neurotechnology and Spine had constant currency and organic growth of 2.1%.
Our U.S. neurotech business posted an organic decline of 1.2% as procedural deferrals impacted sales in the quarter.
Internationally, Neurotechnology and Spine had organic growth of 13.5%.
Our adjusted gross margin of 65.1% was unfavorable approximately 120 basis points from the prior-year quarter.
Adjusted R&D spending was 5.5% of sales.
Our adjusted SG&A was 30.3% of sales, which was favorable to the prior-year quarter by 200 basis points.
In summary for the quarter, our adjusted operating margin was 29.2% of sales, which is a 90 basis points improvement over the prior-year quarter and reflects the impact of the spending discipline previously discussed.
Our fourth quarter had an adjusted effective tax rate of 8%.
Our full-year effective tax rate was 12.6%.
And we expect our full-year effective tax rate to be in the range of 15.5% to 16.5%.
Focusing on the balance sheet, we ended the year with $3 billion of cash and marketable securities, and total debt of $14 billion.
During the quarter, we executed the Wright Medical acquisition, which resulted in the disbursement of $5.6 billion, inclusive of the retirement of Wright's convertible debt.
Turning to cash flow, our year-to-date cash from operations was approximately $3.3 billion.
We will not be repurchasing any shares and we anticipate that capital expenditures will be approximately $650 million.
Anticipating a more normalized year in 2021 and a ramping of investment in our businesses, we expect the free cash flow conversion rate as a percent of adjusted net earnings, including the one -- excluding the one-time impacts from the Wright Medical integration, about 70% to 80%.
Given this variability, we expect organic sales growth to be in the range of 8% to 10% for the full year 2021 when compared to 2019.
Consistent with the pricing environment experienced in both 2019 and 2020, we would expect continued unfavorable price reductions of approximately 1%.
However, excluding the dilutive impact from Wright, we do anticipate expansion of 30 to 50 basis points of operating margin in 2021 for our legacy Stryker business compared to 2019.
Finally, for 2021, we expect adjusted net earnings per diluted share to be in the range of $8.80 to $9.20 for the full year.
This includes the previously announced $0.10 dilution, driven by the addition of the Wright Medical business for the full year.
We also reiterate our previous guidance on cost-saving synergies from the deal of approximately $100 million to $125 million over the next three years.

Summary:
Throughout the quarter, we maintained the financial discipline instituted at the beginning of a pandemic which combined with a favorable tax rate, led to an adjusted earnings per share of $2.81 in the quarter, up approximately 13% versus 2019.
Our organic sales decline was 1.1% in the quarter.
Our adjusted quarterly earnings per share of $2.81 increased 12.9% from the prior year, reflecting strong financial discipline, good operating expense control, and a favorable operational tax rate.
Given this variability, we expect organic sales growth to be in the range of 8% to 10% for the full year 2021 when compared to 2019.
Finally, for 2021, we expect adjusted net earnings per diluted share to be in the range of $8.80 to $9.20 for the full year.