Orthopedics

Feature Article 

Performance and Return-to-Sport After ACL Reconstruction in NFL Quarterbacks

Brandon J. Erickson, MD; Joshua D. Harris, MD; Jacob R. Heninger, BS; Rachel Frank, MD; Charles A. Bush-Joseph, MD; Nikhil N. Verma, MD; Brian J. Cole, MD, MBA; Bernard R. Bach, MD

Abstract

Anterior cruciate ligament (ACL) rupture is a significant injury in National Football League (NFL) quarterbacks. The purpose of this study was to determine (1) return-to-sport (RTS) rate in NFL quarterbacks following ACL reconstruction, (2) performance upon RTS, and (3) the difference in RTS and performance between players who underwent ACL reconstruction and controls. Thirteen quarterbacks (14 knees) who met inclusion criteria underwent ACL reconstruction while in the NFL. Matched controls were selected from the NFL during the same time span to compare and analyze age, body mass index (BMI), position, performance, and NFL experience. Student t tests were performed for analysis of within- and between-group variables. Bonferroni correction was used in the setting of multiple comparisons. Twelve quarterbacks (13 knees; 92%) were able to RTS in the NFL. Mean player age was 27.2±2.39 years. Mean career length in the NFL following ACL reconstruction was 4.85±2.7 years. Only 1 player needed revision ACL reconstruction. In both cases and controls, player performance was not significantly different from preinjury performance after ACL reconstruction (or index year in controls). There was also no significant performance difference between case and control quarterbacks following ACL reconstruction (or index year in controls). There is a high rate of RTS in the NFL following ACL reconstruction. In-game performance following ACL reconstruction was not significantly different from preinjury or from controls.

The authors are from the Midwest Orthopaedics at Rush, Rush University Medical Center, Chicago, Illinois.

Drs Erickson, Harris, and Frank and Mr Heninger have no relevant financial relationships to disclose. Dr Bush-Joseph is an unpaid consultant for The Foundry. Dr Verma receives royalties from Smith & Nephew; is a paid speaker for Arthrosurface; is a paid consultant for Minivasive and Smith & Nephew; has stock options in Omeros; and receives research support from Arthrex, Inc, Smith & Nephew, Athletico, ConMed Linvatec, Miomed, Mitek, and Arthrosurface. Dr Cole receives royalties from Arthrex, Inc, DJ Orthopaedics, and Smith & Nephew; is a paid consultant for Arthrex, Inc, DJ Orthopaedics, Johnson & Johnson, Regentis, and Zimmer; has stock options in Carticept and Regentis; and receives research support from Johnson & Johnson, Medipost, and Zimmer. Dr Bach receives research support from Arthrex, Inc, ConMed Linvatec, DJ Orthopaedics, Ossur, Smith & Nephew, and Tornier.

Correspondence should be addressed to: Brandon J. Erickson, MD, Midwest Orthopaedics at Rush, Rush University Medical Center, 1611 W Harrison St, Ste 300, Chicago, IL 60612 ( berickso.24@gmail.com).

Received: June 20, 2013
Accepted: January 30, 2014
Posted: August 11, 2014

Abstract

Anterior cruciate ligament (ACL) rupture is a significant injury in National Football League (NFL) quarterbacks. The purpose of this study was to determine (1) return-to-sport (RTS) rate in NFL quarterbacks following ACL reconstruction, (2) performance upon RTS, and (3) the difference in RTS and performance between players who underwent ACL reconstruction and controls. Thirteen quarterbacks (14 knees) who met inclusion criteria underwent ACL reconstruction while in the NFL. Matched controls were selected from the NFL during the same time span to compare and analyze age, body mass index (BMI), position, performance, and NFL experience. Student t tests were performed for analysis of within- and between-group variables. Bonferroni correction was used in the setting of multiple comparisons. Twelve quarterbacks (13 knees; 92%) were able to RTS in the NFL. Mean player age was 27.2±2.39 years. Mean career length in the NFL following ACL reconstruction was 4.85±2.7 years. Only 1 player needed revision ACL reconstruction. In both cases and controls, player performance was not significantly different from preinjury performance after ACL reconstruction (or index year in controls). There was also no significant performance difference between case and control quarterbacks following ACL reconstruction (or index year in controls). There is a high rate of RTS in the NFL following ACL reconstruction. In-game performance following ACL reconstruction was not significantly different from preinjury or from controls.

The authors are from the Midwest Orthopaedics at Rush, Rush University Medical Center, Chicago, Illinois.

Drs Erickson, Harris, and Frank and Mr Heninger have no relevant financial relationships to disclose. Dr Bush-Joseph is an unpaid consultant for The Foundry. Dr Verma receives royalties from Smith & Nephew; is a paid speaker for Arthrosurface; is a paid consultant for Minivasive and Smith & Nephew; has stock options in Omeros; and receives research support from Arthrex, Inc, Smith & Nephew, Athletico, ConMed Linvatec, Miomed, Mitek, and Arthrosurface. Dr Cole receives royalties from Arthrex, Inc, DJ Orthopaedics, and Smith & Nephew; is a paid consultant for Arthrex, Inc, DJ Orthopaedics, Johnson & Johnson, Regentis, and Zimmer; has stock options in Carticept and Regentis; and receives research support from Johnson & Johnson, Medipost, and Zimmer. Dr Bach receives research support from Arthrex, Inc, ConMed Linvatec, DJ Orthopaedics, Ossur, Smith & Nephew, and Tornier.

Correspondence should be addressed to: Brandon J. Erickson, MD, Midwest Orthopaedics at Rush, Rush University Medical Center, 1611 W Harrison St, Ste 300, Chicago, IL 60612 ( berickso.24@gmail.com).

Received: June 20, 2013
Accepted: January 30, 2014
Posted: August 11, 2014

Anterior cruciate ligament (ACL) tears are one of the most common knee injuries in both contact and noncontact sports.1 With an incidence of approximately 0.07 per 1000 exposures in high school football players and 0.11 per 1000 exposures for professional football players, it is estimated that there will be up to 200,000 ACL tears annually.2,3 More than half of these ACL tears will be surgically reconstructed.4 Anterior cruciate ligament reconstruction is the standard of care in young athletes.

Although many studies report a high success rate following an ACL reconstruction, data concerning National Football League (NFL) quarterbacks and their return to sport (RTS) after an ACL reconstruction are sparse. Shah et al5 investigated RTS among 49 NFL players, 2 of whom were quarterbacks, but in-game performance before and after ACL reconstruction was not analyzed. The NFL is arguably the most popular sport among the American public, with a total revenue of $9 billion in 2011.6 The average quarterback salary in 2011 was $1.970 million, which was the highest average salary of any position in the NFL.7 Given the importance of the quarterback role within the team framework and the financial interests associated with these NFL players, it is important to determine both the ability to RTS and the player’s postoperative performance following ACL reconstruction.

The primary purpose of this study was to determine (1) RTS rate in NFL quarterbacks following ACL reconstruction, (2) performance upon RTS, and (3) the difference in RTS and performance between players who underwent ACL reconstruction and controls. The authors hypothesized that NFL players who sustained an ACL tear and underwent reconstruction would have (1) a greater than 90% RTS rate; (2) no difference compared with age-, sex-, performance-, and experience-matched controls; and (3) no statistically significant difference in in-game performance parameters compared with controls.

Materials and Methods

Sixteen NFL quarterbacks (17 knees) who tore their ACL and underwent reconstructive surgery were identified. These players were discovered through NFL team websites, publicly available Internet-based injury reports, player profiles/biographies, and press releases. The search was conducted by an orthopedic surgery resident (B.J.E.) and a board-eligible orthopedic surgeon in sports medicine fellowship training (J.D.H.). All players who met the inclusion criteria were included in this study. A player was deemed to RTS if he played in any NFL game after surgery. A player did not RTS if he did not play in any NFL game after surgery. Certain concomitant knee injuries, when known, were deemed acceptable for inclusion, including articular cartilage injury, meniscal tear, and medial or lateral collateral ligament injury (but not both at the same time). The data search was limited to NFL players playing the quarterback position. Additional exclusion criteria included those who sustained bicruciate (ACL and complete posterior cruciate ligament [PCL]) or combined ACL and bicollateral ligament injuries, indicating a more serious knee injury. One quarterback retore his ACL-reconstructed knee. He played 4 seasons prior to retear. The performance statistics from this player were included as if each ACL tear was a separate event. One quarterback was excluded because the tear occurred less than 12 months ago, and 2 were excluded for concomitant PCL injury. One quarterback did not return to the NFL. Therefore, the total number of ACL tears analyzed in this portion of the study was 13 (Figure).

Flowchart of selection process for inclusion of National Football League (NFL) players. Abbreviations: ACL, anterior cruciate ligament; PCL, posterior cruciate ligament.

Figure:

Flowchart of selection process for inclusion of National Football League (NFL) players. Abbreviations: ACL, anterior cruciate ligament; PCL, posterior cruciate ligament.

Demographic data were collected and analyzed, including age at injury, body mass index (BMI), months from injury to RTS, side of injury, quarter of the game in which the injury occurred, years played before and after the injury, and whether the player returned to the NFL the season following the injury. Average in-game performance data were also collected and analyzed, including completions per season, pass attempts per season, completion percentage per season, pass attempts per game, yards per season, yards per attempt, yards per game, touchdowns per season, interceptions per season, number of times sacked per season, average rating per season, and number of fumbles per season. In-game performance variables were analyzed as an average over the preinjury and post-ACL reconstruction course of the players’ careers. In addition, in-game performance variables were analyzed separately in each of the first 4 subsequent seasons after the player returned to the NFL following the injury.

A control group was selected to compare the data to the study group. Controls were matched to study cases based on sex, age, BMI, years of experience in the NFL, and all measured performance variables (Table 1). Anterior cruciate ligament reconstruction occurred at mean of 3.77±2.77 years into a quarterback’s NFL career. An index year was designated for controls, analogous to ACL reconstruction year in cases, as a matched reference year (relative to years’ experience in the NFL) to compare post-ACL reconstruction or post–index year performance. Hence, if a quarterback tore his ACL 4 years into his career, a control was selected with an index year of 4 years into his career. Demographic data (BMI, age, years in the NFL) and in-game performance data were collected and analyzed over the course of their career before and after the index year (each season analyzed individually and collectively).

Pre-ACL Reconstruction in Cases vs Pre-Index Year in Controls

Table 1:

Pre-ACL Reconstruction in Cases vs Pre-Index Year in Controls

Single-variable analyses for all continuous variables (performance measures) within groups were performed using Student t tests. One-sample Kolmogorov-Smirnov goodness-of-fit tests for Gaussian data distribution were performed and confirmed normality of all data. Comparisons between study and control groups were made using paired-sample Student t tests. Comparisons were made between study cases and controls for survival in the NFL and each individual parameter’s overall mean (all years before and all years after ACL reconstruction [or index year]), and each individual year (up to 4 years) following ACL reconstruction (or index year in controls). Bonferroni correction was used to determine significance in the setting of multiple comparisons. All statistical analyses were performed using PASW Statistics Student Version 18.0.0 (Chicago, Illinois).

Results

Thirteen quarterbacks (14 knees) with ACL tears who underwent reconstruction met inclusion criteria and were analyzed. Twelve (92%) quarterbacks (13 knees) were able to RTS in the NFL. Quarterbacks returned to the NFL at a mean of 13±3.9 months following their ACL tear. Mean length of career in the NFL following ACL reconstruction was 4.8±2.7 years. Five (42%) of these quarterbacks are still active in the NFL. Anterior cruciate ligament tears occurred most commonly in the second quarter (57%).

Prior to ACL reconstruction (or index year in controls), quarterbacks who tore their ACL and matched controls had no statistically significant differences in any demographic or performance variable (Table 1). Following ACL reconstruction, quarterbacks showed no significant differences in any of the measured in-game performance variables vs preinjury (Table 2). Likewise, following the index year in controls (Table 3), quarterbacks showed no significant difference in any of the in-game performance variables from pre-index year. Following ACL reconstruction (or index year in controls), there were no significant differences in any of the measured in-game performance variables between study cases and controls as an average over the remainder of their career (Table 4). For each individual year following ACL reconstruction (or index year in controls), there were no significant differences in any of the measured in-game performance variables between study cases and controls (Tables 58).

Pre- vs Post-ACL Reconstruction for Cases

Table 2:

Pre- vs Post-ACL Reconstruction for Cases

Pre- and Post-Index Year for Controls

Table 3:

Pre- and Post-Index Year for Controls

Post-ACL Reconstruction in Cases vs Post-Index Year in Controls

Table 4:

Post-ACL Reconstruction in Cases vs Post-Index Year in Controls

Cases vs Controls: Year One

Table 5:

Cases vs Controls: Year One

Cases vs Controls: Year Two

Table 6:

Cases vs Controls: Year Two

Cases vs Controls: Year Three

Table 7:

Cases vs Controls: Year Three

Cases vs Controls: Year Four

Table 8:

Cases vs Controls: Year Four

Discussion

The purpose of this study was to determine (1) RTS rate in NFL quarterbacks following ACL reconstruction, (2) performance upon RTS, and (3) the difference in RTS and performance between players who underwent ACL reconstruction and controls. The authors hypothesized that NFL players who sustained an ACL tear and underwent reconstruction would have (1) greater than a 90% RTS rate, (2) no statistically significant decrease in in-game performance parameters, and (3) no difference between age-, sex-, BMI-, and experience-matched control players. The study hypotheses were confirmed because there was a 92% rate of RTS in NFL quarterbacks, with no statistically significant decrease in in-game performance parameters from preinjury to postoperatively and no difference in any measured performance variable between study cases and matched controls.

Anterior cruciate ligament tears are common and serious injuries that, if not reconstructed and rehabilitated properly, can signal the end of a NFL quarterback’s career.8 With advances in surgical techniques and technology over the past several decades, a greater number of athletes are recovering from, and playing well after, ACL tears and surgical treatment. The current study sought to determine whether NFL quarterbacks are able to return to the NFL and how well they performed after their ACL reconstruction compared with their preinjury level and compared with a matched control group without an ACL tear. The results showed no difference in performance between pre-ACL tear and post-ACL reconstruction in quarterbacks and no difference in performance when compared with matched NFL control quarterbacks. Prior studies have examined various high school, collegiate, and NFL players with all positions grouped together, but this is the first study to analyze quarterbacks specifically.9,10 These data are encouraging for current NFL quarterbacks who have sustained, or may sustain, an ACL tear in their career.

In this study, almost 60% of ACL tears in NFL quarterbacks occurred in the second quarter vs 14% in each of the first, third, and fourth quarters. Bradley et al11 examined 209 ACL injuries in NFL players and found that they occurred most frequently in the second quarter. Although their study looked at ACL injuries in all NFL players, quarterbacks were included in the study, and, like the current study, it found the highest rate of ACL injuries occurred in the second quarter. Another study examined ACL tears in National Basketball Association players and found that 40% occurred in the fourth quarter.12 Although these studies do not prove a link between fatigue and ACL tears, further studies addressing this in more detail are necessary to elucidate this point further.

Strengths of the current study include its case-control comparative design and use of sport-specific performance parameters. In addition, demographic- and performance-matched controls were used as a comparison group. Limitations of the study include the use of publicly available data, which can be subject to observer bias due to anticipated media and/or public scrutiny. However, this method of subject selection has been used in multiple studies in high-level–evidence sports medicine journals.12–17 Furthermore, no patient-reported or clinician-measured outcomes were available. This includes general health (eg, Short Form 36) and joint-specific (eg, Knee Society Score) scores. Furthermore, patient satisfaction and personal perception of knee pain, function, and stability were unable to be assessed vs preinjury. These factors may influence RTS performance.

Surgical technique information was unobtainable from publicly available sources, although it can be inferred by the treating surgeon based on preferences expressed in publications and/or presentations. Due to the high-profile nature of these athletes, they are unable to be easily contacted to assess these outcome measures. Additionally, the rehabilitation program used postoperatively was unavailable. Although only 1 quarterback was unable to RTS in the NFL following ACL reconstruction, the inability to return cannot solely be attributed to ACL injury and surgery because other confounders inevitably coexist. Furthermore, although all performance-based measures were used to compare pre- and postoperative outcomes and between study cases and controls, other intangibles (eg, team leadership, team-mate motivation) cannot be assessed for relationships.

Conclusion

There is a high rate of RTS in the NFL following ACL reconstruction. In-game performance following ACL reconstruction was not significantly different from preinjury. There was no significant difference in performance between study case and control quarterbacks following ACL reconstruction (or index year in controls).

References

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  2. Prodromos CC, Han Y, Rogowski J, Joyce B, Shi K. A meta-analysis of the incidence of anterior cruciate ligament tears as a function of gender, sport, and a knee injury-reduction regimen. Arthroscopy. 2007; 23(12):1320–1325.e6. doi:10.1016/j.arthro.2007.07.003 [CrossRef]
  3. Arendt EAAmerican Orthopaedic Society for Sports Medicine, American Academy of Orthopaedic Surgeons. Orthopaedic Knowledge Update: Sports Medicine 3. 3rd ed. Rosemont, IL: American Academy of Orthopaedic Surgeons; 2004.
  4. Frank CB, Jackson DW. The science of reconstruction of the anterior cruciate ligament. J Bone Joint Surg Am. 1997; 79(10):1556–1576.
  5. Shah VM, Andrews JR, Fleisig GS, McMichael CS, Lemak LJ. Return to play after anterior cruciate ligament reconstruction in National Football League athletes. Am J Sports Med. 2010; 38(11):2233–2239. doi:10.1177/0363546510372798 [CrossRef]
  6. Daly D. Another way to look at the NFL’s $9 billion in revenue. The Washington Times. February24, 2011.
  7. Sports Illustrated. NFL’s average salaries by position. http://www.si.com/nfl/photos/2013/01/31/nfl-average-salaries-position?eref=sircrc. Accessed November 7, 2013.
  8. Cheatham SA, Johnson DL. Anatomic revision ACL reconstruction. Sports Med Arthroscopy Review. 2010; 18(1):33–39. doi:10.1097/JSA.0b013e3181c14998 [CrossRef]
  9. Carey JL, Huffman GR, Parekh SG, Sennett BJ. Outcomes of anterior cruciate ligament injuries to running backs and wide receivers in the National Football League. Am J Sports Med. 2006; 34(12):1911–1917. doi:10.1177/0363546506290186 [CrossRef]
  10. McCullough KA, Phelps KD, Spindler KP, et al. Return to high school- and college-level football after anterior cruciate ligament reconstruction: a Multicenter Orthopaedic Outcomes Network (MOON) cohort study. Am J Sports Med. 2012; 40(11):2523–2539. doi:10.1177/0363546512456836 [CrossRef]
  11. Bradley JP, Klimkiewicz JJ, Rytel MJ, Powell JW. Anterior cruciate ligament injuries in the National Football League: epidemiology and current treatment trends among team physicians. Arthroscopy. 2002; 18(5):502–509. doi:10.1053/jars.2002.30649 [CrossRef]
  12. Harris JD, Erickson BJ, Bach BR Jr, et al. Return-to-sport and performance after anterior cruciate ligament reconstruction in National Basketball Association players. Sports Health. 2013; 5(6):562–568. doi:10.1177/1941738113495788 [CrossRef]
  13. Namdari S, Baldwin K, Anakwenze O, Park MJ, Huffman GR, Sennett BJ. Results and performance after microfracture in National Basketball Association athletes. Am J Sports Med. 2009; 37(5):943–948. doi:10.1177/0363546508330150 [CrossRef]
  14. Namdari S, Scott K, Milby A, Baldwin K, Lee GC. Athletic performance after ACL reconstruction in the Women’s National Basketball Association. Phys Sportsmed. 2011; 39(1):36–41. doi:10.3810/psm.2011.02.1860 [CrossRef]
  15. Cerynik DL, Lewullis GE, Joves BC, Palmer MP, Tom JA. Outcomes of microfracture in professional basketball players. Knee Surg. 2009; 17(9):1135–1139. doi:10.1007/s00167-009-0765-5 [CrossRef]
  16. Amin NH, Old AB, Tabb LP, Garg R, Toossi N, Cerynik DL. Performance outcomes after repair of complete Achilles tendon ruptures in National Basketball Association players. Am J Sports Med. 2013; 41(8):1864–1868. doi:10.1177/0363546513490659 [CrossRef]
  17. Erickson BJ, Cvetanovich GL, Bush-Joseph C, et al. Performance and return-to-sport after anterior cruciate ligament reconstruction in male major league soccer players. Orthop J Sports Med. 2013. doi:10.1177/2325967113497189. [CrossRef]

Pre-ACL Reconstruction in Cases vs Pre-Index Year in Controls

Preoperative (or Index) Variable Mean±SD
Pa
Study Cases Controls
Age, y 27.2±2.39 26.8±2.48 .717
BMI, kg/m2 27.4±1.41 27.3±0.95 .897
Seasons NFL experience 3.77±2.77 3.77±2.77 .999
Games played 35.2±38.8 37.1±20.6 .890
Games played per season 7.52±4.45 10.5±2.71 .063
Completions per season 114±106 174±81.4 .140
Passing attempts 192±170 298±127 .109
Passing attempts per game 17.4±11.3 25.7±6.70 .057
Completion % per season 42.9±17.6 57.6±3.92 .016
Passing yards per season 1296±1210 1992±954 .139
Passing yards per attempt 4.38±2.18 6.59±0.58 .005
Passing yards per game 114±77.8 171±50.8 .061
Passing touchdowns per season 8.34±8.83 11.7±6.35 .313
Interceptions per season 5.73±4.41 8.52±2.92 .116
Sacks per season 13.7±10.9 23.3±11.7 .067
Quarterback passer rating 51.3±28.1 79.7±10.3 .006
Fumbles per season 3.20±3.24 5.20±2.22 .114

Pre- vs Post-ACL Reconstruction for Cases

Variable Mean±SD
Pa
Before After
Games played per season 7.52±4.45 7.86±4.28 .655
Completions per season 114±106 126±128 .950
Passing attempts per season 192±170 206±200 .935
Passing attempts per game 17.4±11.3 19.7±12.0 .690
Completion % per season 42.9±17.6 46.2±15.6 .537
Passing yards per season 1296±1210 1358±1499 .824
Passing yards per attempt 4.38±2.18 5.07±2.03 .298
Passing yards per game 114±77.8 126±94.1 .564
Passing touchdowns per season 8.34±8.83 8.06±10.3 .860
Interceptions per season 5.73±4.41 5.44±4.57 .823
Sacks per season 13.7±10.9 10.8±10.4 .280
Quarterback passer rating per season 51.3±28.1 58.5±25.2 .386
Fumbles per season 3.20±3.24 2.88±2.07 .694

Pre- and Post-Index Year for Controls

Variable Mean±SD
Pa
Before After
Games played per season 10.5±2.71 6.41±5.26 .017
Completions per season 174±81.4 146±100 .012
Passing attempts per season 298±127 239±159 .008
Passing attempts per game 25.7±6.70 24.1±11.2 .059
Completion % per season 57.6±3.92 55.8±6.35 .023
Passing yards per season 1992±954 1198±1296 .017
Passing yards per attempt 6.59±0.58 4.35±3.11 .022
Passing yards per game 171±50.8 107±98.9 .035
Passing touchdowns per season 11.7±6.35 6.87±7.60 .007
Interceptions per season 8.52±2.92 4.77±4.59 .009
Sacks per season 23.3±11.7 12.7±12.6 .015
Quarterback passer rating per season 79.7±10.3 53.5±37.9 .020
Fumbles per season 5.20±2.22 3.64±3.93 .485

Post-ACL Reconstruction in Cases vs Post-Index Year in Controls

Postoperative (or Index) Variable Mean±SD
Pa
Study Cases Controls
Seasons NFL experience 4.85±2.70 3.85±3.69 .354
Games played 39.9±31.7 34.2±32.9 .648
Games played per season 7.86±4.28 6.41±5.26 .417
Completions per season 126±128 146±100 .727
Passing attempts per season 206±200 239±159 .711
Passing attempts per game 19.7±12.0 24.1±11.2 .451
Completion % per season 46.2±15.6 55.8±6.35 .144
Passing yards per season 1358±1499 1198±1296 .766
Passing yards per attempt 5.07±2.03 4.35±3.11 .490
Passing yards per game 126±94.1 107±98.9 .604
Passing touchdowns per season 8.06±10.3 6.87±7.60 .729
Interceptions per season 5.44±4.57 4.77±4.59 .704
Sacks per season 10.8±10.4 12.7±12.6 .670
Quarterback passer rating 58.5±25.2 53.5±37.9 .698
Fumbles per season 2.88±2.07 3.64±3.93 .447

Cases vs Controls: Year One

Postoperative (or Index) Variable Mean±SD
Pa
Study Cases Controls
Completions per season 122±136 177±135 .359
Completion % per season 58.5±6.50 56.6±5.55 .483
Passing attempts per season 197±208 281±205 .360
Passing attempts per game 19.6±11.0 23.6±13.5 .454
Passing yards per season 1407±1570 2152±1720 .305
Passing yards per attempt 6.71±1.41 6.64±1.06 .911
Passing yards per game 140±93.1 167±106 .525
Passing touchdowns per season 8.23±10.3 13.0±10.7 .305
Interceptions per season 5.31±5.53 6.56±5.68 .612
Sacks per season 11.4±12.5 20.9±14.7 .118
Quarterback passer rating 75.6±23.3 82.6±11.5 .362
Fumbles per season 2.62±2.53 5.67±3.94 .038

Cases vs Controls: Year Two

Postoperative (or Index) Variable Mean±SD
Pa
Study Cases Controls
Completions per season 146±137 125±70.3 .667
Completion % per season 56.4±23.4 62.1±4.93 .516
Passing attempts per season 246±230 202±117 .596
Passing attempts per game 20.7±14.8 24.6±11.6 .551
Passing yards per season 1724±1668 1357±808 .534
Passing yards per attempt 5.89±2.51 6.63±0.76 .438
Passing yards per game 138±107 167±90.2 .542
Passing touchdowns per season 11.3±12.1 7.50±4.31 .356
Interceptions per season 7.73±8.36 6.00±3.16 .541
Sacks per season 13.5±12.4 14.5±9.43 .844
Quarterback passer rating 75.4±24.7 81.5±8.90 .519
Fumbles per season 3.64±3.78 4.00±2.27 .812

Cases vs Controls: Year Three

Postoperative (or Index) Variable Mean±SD
Pa
Study Cases Controls
Completions per season 166±136 155±128 .870
Completion % per season 51.2±20.2 59.8±4.43 .255
Passing attempts per season 272±212 254±200 .855
Passing attempts per game 25.3±14.2 22.8±11.0 .681
Passing yards per season 2007±1770 1817±1490 .812
Passing yards per attempt 5.67±2.95 7.28±1.09 .165
Passing yards per game 177±106 163±79.1 .755
Passing touchdowns per season 13.0±13.2 9.25±8.40 .495
Interceptions per season 7.50±5.02 8.00±6.70 .858
Sacks per season 16.8±13.3 17.1±15.9 .963
Quarterback passer rating 70.5±30.3 83.7±20.7 .311
Fumbles per season 3.40±3.37 5.00±4.41 .395

Cases vs Controls: Year Four

Postoperative (or Index) Variable Mean±SD
Pa
Study Cases Controls
Completions per season 221±158 165±170 .533
Completion % per season 58.3±4.59 60.9±14.1 .655
Passing attempts per season 364±248 273±267 .523
Passing attempts per game 28.8±10.4 22.4±13.0 .332
Passing yards per season 2628±1881 1906±2002 .500
Passing yards per attempt 6.63±1.40 6.83±1.21 .780
Passing yards per game 201±94.3 154±99.0 .384
Passing touchdowns per season 15.4±12.9 9.00±9.02 .302
Interceptions per season 9.29±6.65 7.00±7.33 .552
Sacks per season 18.3±12.9 19.6±18.9 .884
Quarterback passer rating 76.6±20.7 84.2±27.1 .565
Fumbles per season 4.71±3.55 3.57±3.05 .530

10.3928/01477447-20140728-59

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