He was eventually discovered by American coaches in a camp run by ex-Georgetown player, Godwin Owinje, in Lagos.

[2] He later visited South Africa for "Basketball Without Borders," with several other players, including Serge Ibaka, Dikembe Mutombo, Dirk Nowitzki and Luol Deng.

[4] Soon after arriving in the United States, Zanna attended Bishop McNamara High School in Forestville, Maryland.

He finished his sophomore season by posting 17 points and 15 rebounds against Paul VI Catholic High School in the WCAC Tournament quarter-finals.

As a junior in 2007–08, he averaged 15.0 points, 13.5 rebounds, 3.4 blocks, 1.5 assists and 1.4 steals per game as he earned All-Washington Catholic Athletic Conference accolades.

[5] On 19 November 2008, Zanna signed a National Letter of Intent to play college basketball for the University of Pittsburgh.

[6] He was also recruited by Boston College, Connecticut, Oklahoma, Providence, South Florida, Saint Joseph's, Villanova, and West Virginia.

[7][8] As a senior in 2008–09, Zanna averaged 14.6 points and 11.8 rebounds per game as he was named first-team All-MET by the Washington Post and earned Independent private school all-league honors.

[1] As a freshman at Pittsburgh in 2009–10, Zanna managed just three minutes of action in the first game before a shoulder injury forced him to miss the entire season as he applied for a medical hardship waiver.

On 29 September 2014, he signed with the Thunder as he joined former Pitt teammate, Steven Adams, for the team's training camp.

[10][11] Zanna appeared in all seven of Oklahoma City's preseason contests, averaging 4.4 points and 5.0 rebounds in 17.4 minutes per game before he was waived by the team on October 24, 2014.

[20] On April 26, 2017, Zanna and Nanterre parted ways one day after winning the FIBA Europe Cup title.

Zanna helped Nes Ziona reach the 2018 Israeli League Playoffs, where they eventually were eliminated by Maccabi Tel Aviv.

[26] On February 16, 2019, Zanna recorded a season-high 22 points, shooting 9-of-12 from the field, along with six rebounds and three steals in a 90–78 win over Hapoel Be'er Sheva.

[27] On September 22, 2019, Zanna signed a one-year deal with Afyon Belediye of the Turkish Basketbol Süper Ligi.