Arthroscopic labral repair and shoulder stabilization in National Hockey League players are associated with decreased performance in the first year of return to play with return to baseline in the second year

Abstract

Background

Few studies have assessed performance in National Hockey League players following shoulder labral repair and stabilization using advanced statistics. Our objective was to assess National Hockey League player performance following shoulder labral repair and stabilization

Methods

National Hockey League players who underwent surgical procedures for labral repair and stabilization between 2008 and 2022 were identified using a publicly available injury database. We obtained demographic and outcome data for one-year preinjury and two years postinjury. Our primary outcome was wins above replacement per 60 minutes played (WAR/60). A matched cohort based on position, draft year, and index season performance was established. Outcomes were compared between cases and controls with a paired t-test.

Results

We identified 94 eligible patients who underwent shoulder labral repair or stabilization. Preinjury, postinjury year one, and postinjury year two WAR/60 were 0.03, 0.02, and 0.03 compared to 0.03, 0.06, and 0.05 in controls (P = .33, .00, .07, respectively). Offensive performance was lower both one and two years postinjury when compared to controls (P = .00, P = .01, respectively).

Conclusions

Shoulder labral tears and glenohumeral instability requiring surgical management are associated with decreased overall performance one year postsurgery with return to baseline by postinjury year two. Offensive performance remained decreased at the second postinjury year.

Shoulder dislocation occurs at a rate of 0.02 per 1000 game exposures in National Hockey League (NHL) players with 47.8% of cases managed operatively.²² NHL players have a return-to-play rate of 87.5-100% after orthopedic shoulder procedures^4,14,19,22 with an average postsurgical career duration of 4.8 seasons.¹⁰ Shoulder arthroscopy in general is associated with a decreased performance score (a mathematical translation of goals, assists, and points) 1-year postsurgery with a return to baseline by year two.¹⁰ Noninstability shoulder arthroscopy is associated with decreased games played and a decreased short-term performance score.¹⁴ Isolated labral repair is associated with no change in shots on goal per game both presurgery and postsurgery.¹⁹ Stabilization procedures have been shown to be associated with no difference in goals, assists, points, point shares,²² games played, and performance score.¹⁴ One study found that stabilization was associated with significantly decreased shooting percentage postsurgery.²² Nonoperative management of instability has been shown to be associated with decreased points per game compared to operative management.²²

While the traditional statistics used to assess performance following shoulder surgery do broadly illustrate the effect of shoulder surgery on NHL performance, these statistics are influenced by randomness as hockey is a low-scoring game with individual players scoring relatively few goals.³ Reliance on these statistics for performance evaluation can lead to systematic misjudgment³ as these statistics are influenced by strategy, usage, teammate performance, game script, and other factors not directly related to a player’s innate ability.

Prior research has demonstrated that advanced statistics are better predictors of future performance than traditional statistics^3,15,17 while providing better insight into performance in multiple phases of the game. Corsi⁷ and expected goals use scoring opportunities as performance proxies to lessen the effect of randomness on performance.^3,15 These metrics can be regressed by the players on ice at any given time to adjust for the impact of teammate and opponent performance (Regularized Adjusted Plus-Minus [RAPM]) and then included in models encompassing further variables (zone starts, hits, giveaways, takeaways, faceoffs, blocked shots) and expressed as goals above replacement in offensive and defensive situations and as overall wins above replacement (ie, the number of additional wins a player contributes to their team per unit time).¹⁵

Understanding the ramifications of shoulder labral repair and stabilization on athletic performance is required for setting treatment expectations, predicting performance, and comparing treatments. The true impact of labral repair and stabilization on hockey performance is unknown, partly as a result of the limitations of traditional statistics used in prior studies. The objective of this study was to assess NHL performance following isolated labral repair and stabilization. Our primary outcome is expected wins above replacement. Secondary outcomes include games played, Corsi, expected goals, offensive goals above replacement per 60 minutes played, defensive goals above replacement per 60 minutes played, and the RAPM-adjusted forms of these. Our hypothesis is that players will recover full performance following shoulder labral repair and stabilization.

Methods

Institutional review board approval was not required for this study because, similar to prior studies evaluating sports performance following injury,^6,10,12, 13, 14^,16,20,22 cases were identified in a systematic fashion using publicly available data. We identified NHL players who sustained a shoulder injury between the 2008/2009 and 2021/2022 seasons using the publicly available NHL Injury Viz database of shoulder injuries.¹⁸ We carried out a web search of all players listed as having a shoulder injury to determine the surgical indication and procedure performed. We included players who underwent isolated labral repair (superior labrum anterior-posterior tear repair) and players who underwent stabilization procedures for glenohumeral instability (Bankart repair, Latarjet procedure, and bony glenoid augmentation). We included players who returned to play postinjury and had a minimum of one year of preinjury data. We excluded players who did not undergo surgery, players who did not have public documentation of the injury or surgery performed, players without preinjury or postinjury data, players who failed to return, and players with multiple surgeries without at least a full season of data before or any of the surgeries. The index season was defined as the regular season immediately preceding injury/surgery; the I+1 season was the season immediately following surgery, regardless of whether it was a full season. In one case, a player took 2 seasons to return to play in the NHL (playing the first full postinjury season in the American Hockey League); in this case, the first full NHL season following injury was used as the I+1 season. Demographic data were obtained from Hockey Reference,²¹ Hockey DB,¹¹ and Evolving Hockey.⁹ Outcome data were obtained from Evolving-Hockey,⁹ a website providing access to traditional and advanced hockey statistics that has previously been used in sports science research.⁵ We collected data from the first full season prior to injury, subsequent surgery, and data for the following two seasons after injury.

Outcome measures

We employed various advanced metrics to assess postinjury performance. In general, these metrics increase the overall sample size of performance events by using shots and scoring chances to quantify performance which can mitigate the effect of randomness on outcomes³; these metrics have previously been used in sports research to assess postinjury performance. ¹ Corsi (comprising Corsi for/against [shot attempts for/against while a player is on the ice] and Corsi percentage [Corsi for/Corsi for-Corsi against] while a given player is on the ice) is considered a proxy of territorial advantage via puck possession and has been shown to be a good indicator of team performance.¹⁵ An expected goal is the shot location-based probability of a scoring chance resulting in a goal.⁷ Corsi and expected goals ameliorate the effect of randomness on outcomes due to the low number of goals scored in hockey, with expected goals building on Corsi by quantifying and including the probability of scoring on a given shot.³ RAPM enhances these metrics by regressing them against various player combinations to adjust for the influence of teammate and opponent performance to isolate the impact of any individual on ice player on each metric.⁸ To further improve these metrics, RAPM expected goals for and against can be used in a linear regression model alongside shots, hits, zone starts, time on ice, turnovers, takeaways, faceoffs, and blocked shots with adjustment for team quality to quantify a player's contribution relative to a replacement-level player (the mean player below the top 13 forwards and top 7 defensemen in time on ice per team) in terms of goals scored or prevented.²³ Wins above replacement (WAR) further extends this analysis by translating a player's offensive and defensive contributions into wins added or subtracted compared to a replacement-level player.²⁴

Cohort

A 1:1 position and draft year matched was created. In three cases where an appropriate draft year-matched player did not exist, a similar player active during the index and postinjury seasons was chosen. We selected players with similar career games played, seasons played, and performance metrics as index players for the seasons of interest

Statistical analysis

Data analysis was performed using IBM SPSS Statistics, version 29 (IBM Corp., Armonk, NY, USA). Outcome data were compared among individual players between each paired season (injury-1 and injury +1, injury −1 and injury +2) with a paired t-test assuming equal variance. Data at each time point (injury-1, injury + 1, injury + 2) were compared between cases and controls with a paired t-test assuming equal variance. A P value of <0.05 was used as a cutoff for a statistically significant result.

Results

We identified 475 shoulder injury reports between the 2008-2009 and 2021-2022 seasons. Once duplicates were removed, 346 separate players were identified. 206 players who did not undergo surgery, 41 who did undergo surgery but did not have a specified injury type, 7 players who underwent a surgical procedure not included in this study, 4 players who had not played one full season prior to the injury, 6 players who failed to return following injury, 1 goalie, and 1 player with multiple surgeries in multiple consecutive seasons were excluded. In total, 80 players were identified via database searching. Eleven players were identified through other news articles and media reports. In total we included 91 players with 94 total shoulder injuries, of which 55 were isolated labral injuries and 39 were glenohumeral instability. The mean age was 26.6 years and the mean draft position was 66.2. There were 69 forwards and 25 defensemen.

Table I displays outcome data for the index, postinjury year one, and postinjury year two seasons while Table II displays a comparison of cases and controls at index, postinjury year one, and postinjury year two among players who underwent isolated labral repair. Compared to controls, there was a significant decrease in games played, offensive goals above replacement, and wins above replacement at postsurgery year one and games played and offensive goals above replacement at postsurgery year two.

Table I.

Preinjury and postinjury performance.

	I-1	I+1	P	I+2	P
n	94	94		76
Games played	58.9	54.9	.17	55.5	.03
Expected goals per 60 minutes played	0.60	0.58	.43	0.60	.59
RAPM expected goal differential per 60 minutes played	0.02	0.00	.08	0.03	.75
RAPM Corsi differential per 60 minutes played	0.58	0.16	.23	0.53	.87
RAPM expected goals for per 60 minutes played	0.02	0.00	.10	0.02	.83
RAPM expected goals against per 60 minutes played	0.00	0.01	.41	−0.01	.52
RAPM Corsi for per 60 minutes played	0.61	0.16	.07	0.48	.57
RAPM Corsi against per 60 minutes played	0.03	0.00	.88	−0.05	.73
Offensive goals above replacement per 60 minutes played	0.15	0.11	.14	0.17	.60
Defensive goals above replacement per 60 minutes played	0.00	−0.02	.41	0.01	.44
Wins above replacement per 60 minutes played	0.03	0.02	.16	0.03	.69

RAPM, Regularized Adjusted Plus-Minus.

Table II.

Cases vs. controls.

	I-1	C I-1	P	I+1	C I+1	P	I+2	C I+2	P
Games played	58.9	62.3	.14	54.9	68.3	.00	55.5	64.8	.00
Offensive goals above replacement per 60 minutes played	0.15	0.19	.26	0.11	0.32	.00	0.17	0.27	.01
Defensive goals above replacement per 60 minutes played	0.00	−0.01	.74	−0.02	0.00	.40	0.01	−0.01	.54
Wins above replacement per 60 minutes played	0.03	0.03	.33	0.02	0.06	.00	0.03	0.05	.07

Discussion

The primary finding of this study is that labral repair and glenohumeral stabilization are associated with significantly decreased overall hockey performance compared to matched controls at postinjury year one, with decreased offensive performance at both the first and second postoperative year. These findings refute our hypothesis that labral repair and glenohumeral stabilization will not affect a player’s performance following return to play. Our primary objective was to determine the effect that orthopedic shoulder procedures can have on hockey performance among NHL players. Our results suggest that overall performance is decreased following labral repair and glenohumeral stabilization, which is driven by decreased offensive performance. Overall performance returns to baseline postinjury year two, though decreased offensive performance persists. We observed no significant change in performance compared to preinjury. This is likely due to the fact that the mean age of players in this study was 26.6 years old, which is younger than the ages of peak scoring in NHL players (27-28 in forwards and 28-29 in defenseman).² Thus, shoulder injuries led to a decreased level of performance improvement compared to age-matched controls.

Prior research has demonstrated that shoulder arthroscopy for all indications is associated with a decreased performance score (a mathematical translation of goals, assists, and points) 1-year postsurgery with a return to baseline by year two, ¹⁰ while noninstability shoulder arthroscopy has been shown to be associated with decreased games played and a decreased short-term performance score.¹⁴ Stabilization procedures have been shown to be associated with significantly decreased postsurgery shooting percentage²² but no difference in goals, assists, points, point shares,²² games played, and performance score.¹⁴ Our data suggest a similar relationship, with decreased overall performance one year postsurgery with a return to the expected value relative to controls at postsurgery year two, though offensive performance remained decreased at the second postoperative year compared to controls.

A large advantage of our study was the use of advanced statistics for performance evaluation which address limitations associated with traditional hockey statistics. These outcomes include expected goals and Corsi percentages as well as their RAPM and wins above replacement transformations. We have demonstrated that overall performance as measured by expected wins above replacement (the summation of offensive and defensive performance) is decreased following isolated labral repair and glenohumeral stabilization. This difference was driven by a significant decrease in offensive expected goals above replacement with no significant change in defensive performance. In players who underwent isolated labral repair, decreased offensive performance persists to postinjury year two.

This study has several limitations. The use of publicly available data induces possible observer bias as there is the possibility that some players were missed that had differing performance outcomes compared to included players. However, publicly available data are frequently used in studies comparing outcomes following orthopedic surgical procedures^6,13,16 and were improved upon in our case using a publicly available database previously compiled in a systematic fashion.¹⁸ Furthermore, we did not have access to information on surgical technique, concomitant procedures, or rehabilitation protocols used, precluding further stratification and analysis, including comparisons of different surgical procedures.

Conclusion

Shoulder labral repair and stabilization are associated with significantly decreased hockey performance one year following surgery compared to matched controls. This is driven by decreased offensive performance. Overall performance returns to baseline in the second year of return to play though offensive performance remains decreased relative to controls.

Disclaimers:

Funding: No funding was disclosed by the authors.

Conflicts of interest: Michael Pickell is a consultant for ConMed and Arthrex. Bogdan A. Matache has received financial support from The Ottawa Hospital Department of Surgery Junior Faculty Research Grant, Arthrex, and Pendopharm. The other authors, their immediate families, and any research foundation with which they are affiliated have not received any financial payments or other benefits from any commercial entity related to the subject of this article.