Citations

Objectives: There is a paucity of research comparing the outcomes of medial ulnar collateral ligament (MUCL) repair with internal bracing to isolated MUCL reconstruction in professional baseball players. Further, the practice of supplementing a MUCL reconstruction with an internal brace, a "hybrid" reconstruction, has increased in the surgical treatment of MUCL injuries for professional baseball players, without any currently known published research defining the clinical outcomes of this modification. We sought to investigate the trends and outcomes of MUCL repair with internal bracing and "hybrid" MUCL reconstruction with internal bracing. Using a matched cohort analysis, we also sought to compare the clinical outcomes of both MUCL repair with internal bracing and "hybrid" MUCL reconstruction with internal bracing to isolated MUCL reconstructions, without internal bracing, in professional baseball players. Methods: The MLB Health and Injury Tracking System was used to identify all professional baseball players who underwent MUCL surgery, regardless of surgery technique, from 2010 to 2023. Professional players of all levels (MLB and MiLB) and players of all positions were included. Player demographics, injury characteristics, surgical details, and postoperative outcomes were obtained. Player demographics included age at surgery, position of play, professional level of play and surgical technique. Outcomes assessed were return to play (RTP) status, time to RTP, return to same level of play (RTSL), time to RTSL, revision MUCL surgery, and time to revision MUCL surgery, with a minimum of 2 years of follow up. Players were considered to have RTP if they participated in at least one game at any professional level. RTSL was defined as returning to the same league of professional play or higher. Patients undergoing MUCL repair and "hybrid" MUCL reconstruction with internal bracing were independently compared to propensity matched patients undergoing isolated MUCL reconstruction, without internal bracing, to assess for a difference in postoperative outcomes. Four subgroup analyses were conducted by further categorizing patients to MLB players, MiLB players, pitchers, and position players. Results: 76 patients underwent MUCL repair with internal bracing from 2016-2021 and were successfully propensity matched to 76 patients undergoing isolated MUCL reconstructions. Baseline patient demographic variables of MUCL repairs were statistically similar to those of controls except for age at time of surgery (24.5 vs 21.8; p<0.001). 81 patients underwent "hybrid" MUCL reconstructions with internal bracing from 2016-2021 and were successfully propensity matched to 81 patients undergoing isolated MUCL reconstructions. Baseline demographic variables of "hybrid" MUCL reconstructions were statistically similar to those of controls except for age at time of surgery (24.3 vs. 23.3; p=0.006). Compared to isolated MUCL reconstruction controls, all patients undergoing MUCL repair demonstrated significantly shorter time to RTP (mean 421.2 vs. 546.2 days; p<0.001), shorter time to RTSL (mean 436.2 vs. 558.8 days; p<0.001), and shorter time to revision (mean 465.2 vs.1648 days; p=0.036). The number of patients who RTP at any level, RTSL, and number of revision surgeries were not significantly different. Compared to isolated MUCL reconstruction controls, all patients undergoing "hybrid" MUCL reconstructions demonstrated no significant differences with respect to the number of patients who RTP, time to RTP, number of patients who RTSL, days to RTSL, number of revision surgeries, and time to revision surgery. In MLB players only, compared to isolated MUCL reconstruction controls, patients who underwent MUCL repairs demonstrated significantly shorter time to RTP (mean 282.8 vs 507.3 days; p=0.008) and shorter time to RTSL (mean 299.7 vs. 598.0 days; p = 0.024). No other outcomes were significant. In MLB players only, compared to isolated MUCL reconstruction controls, patients who underwent "hybrid" MUCL reconstructions demonstrated significantly shorter time to RTP (mean 436.2 vs. 525.3 days; p=0.026). No other outcomes were significant. In MiLB players only, compared to isolated MUCL reconstruction controls, patients who underwent MUCL repairs demonstrated significantly shorter time to RTP (mean 444.3 vs 550.7 days; p<0.001) and shorter time to RTSL (mean 451.7 vs. 556.5 days; p<0.001). No other outcomes were significant. In MiLB players only, compared to isolated MUCL reconstruction controls, patients who underwent "hybrid" MUCL reconstructions demonstrated no significant differences in outcomes. In evaluating pitchers only, compared to isolated MUCL reconstruction controls, patients undergoing MUCL repair demonstrated significantly shorter time to RTP (mean 421.7 vs. 578.6 days; p<0.001), shorter time to RTSL (mean 434.8 vs. 591.6 days; p <0.001), and shorter time to revision surgery (mean 465.2 vs.1648 days; p=0.036). No other outcomes were significant. In pitchers only, compared to isolated MUCL reconstruction controls, patients undergoing "hybrid" MUCL reconstructions demonstrated significantly shorter time to RTP (mean 488.1 vs. 549.0 days; p=0.013) and shorter time to RTSL (mean 505.7 days vs. 577.0 days, respectively; p=0.021). No other outcomes were significant. Notably, all revision surgeries in occurred in pitchers only. Conclusions: Based on a matched cohort anaylsis of professional baseball players undergoing MUCL surgery, when compared to an isolated MUCL reconstruction, MUCL repair with internal bracing may allow for a shorter time to RTP and RTSL, with a shorter time to revision surgery. For pitchers, "hybrid" MUCL reconstruction may allow for a shorter time to RTP and RTSL. For MLB players, "hybrid" MUCL reconstruction may allow for a shorter RTP.

Objectives: The number of medial ulnar collateral ligament (MUCL) reconstructions are increasing. The epidemiology surrounding revision MUCL reconstructions in professional baseball players has not been well defined. The purpose of this study was to report the epidemiology of revision MUCL reconstruction in professional baseball players. The authors hypothesized that the number of revision MUCL reconstructions would increase over time and that the return to sport rate at the same level of play would be less than 70%. Methods: All professional baseball pitchers who underwent revision MUCL reconstruction between 2010-2023 were identified using the MLB Health and Injury Tracking System (HITS). Rate of return and time to return to play (RTP) and return to same level of play (RTSL) was recorded and analyzed for pitchers with a minimum follow up of 2 years. Surgical variables including technique and graft choice were also recorded. Results: Overall, 191 pitchers (avg age 26.0 years), underwent revision MUCL reconstruction. The average time between primary and revision surgery was 1,381 days (45 months). 130 (68%) of these players were MLB pitchers and the other 61 (32%) were MiLB pitchers. 59% of pitchers were able to RTSL at an average of 604 ± 250 days after surgery. 2023 was the year with most revision MUCL reconstructions (n = 27) and the fewest reconstructions were performed in 2010 and 2011 (n = 4). Monthly distribution demonstrates the highest surgery months to be May (17%), June (20%), and July (17%). Hamstring tendon autograft was found to be the most commonly used graft source (n = 90, 47%), compared to palmaris longus autograft (n = 67, 35%). No significant differences were found in the types of grafts used over time ( P = .238 for palmaris and P = .133 for hamstring). In terms of tunnel configuration, both the Modified Jobe and Docking techniques were used in equal occurrence (n = 70, 37%) Conclusions: Following revision MUCL reconstruction, only 72% of professional baseball pitchers were able to return to play at any level at an average of 556 days (18 months), and only 59% were able to return to the same level of play at an average of 604 days (20 months). The average time between primary and revision MUCL reconstruction was 45 months (3.75 years). Pitchers should be counseled on the relatively low RTSL rate and the prolonged time to RTSL.

Objectives: Value based decision making regarding nonoperative management vs. early surgical stabilization for first-time anterior shoulder instability (ASI) events remains controversial. Thus, the purpose of this study was to perform 1) a systematic review of the current literature and 2) a Markov model-based cost-effectiveness analysis comparing an initial trial of nonoperative management to arthroscopic Bankart repair (ABR) for first-time ASI. Methods: A Markov Chain Monte Carlo probabilistic model (Figure 1) was developed to evaluate the outcomes and costs of 1,000 simulated patients (average age » 20 years old) with first-time ASI undergoing nonoperative management vs. ABR. Utility values, recurrence rates, and transition probabilities were derived from the published literature. Costs were determined based on the typical patient undergoing each treatment strategy at our institution. Outcome measures included costs, quality-adjust life-years (QALYs), and the incremental cost-effectiveness ratio (ICER). Probabilities of recurrence as well as the utility of each treatment strategy were obtained from the literature search as described above. Probabilities were pooled across studies to obtain a weighted average for both nonoperative treatment and ABR. Similarly, studies reporting scores on the Western Ontario Shoulder Instability Index (WOSI) scale were utilized to approximate shoulder-related quality of life after each treatment strategy and outcome. Costs for each treatment strategy and transition state in the model were considered from the payer perspective (commercial or government) and obtained from institutional data at a large, academic medical center. Results: The Markov model with Monte Carlo microsimulation demonstrated average (± standard deviation) costs for nonoperative management and ABR of $38,649 ± 10,521 and $43,052 ± 9,352, respectively. Total QALYS acquired over the 10-year time horizon were 7.7 ± 0.4 and 8.4 ± 0.5 for nonoperative management and ABR, respectively. The ICER comparing ABR to nonoperative management was found to be just $5,725/QALY, which falls substantially below the $50,000 willingness-to-pay (WTP) threshold (Figure 2). The mean number of recurrences were 2.6 ± 0.3 and 1.2 ± 0.2 for patients initially assigned to the nonoperative and ABR treatment groups, respectively. Out of 1,000 samples run over 1,000 trials, ABR was the optimal strategy in 98.7% of cases, with nonoperative management the optimal strategy in 1.3% of cases (Figure 3). Conclusions: The primary findings of this systematic review and cost-effectiveness analysis were as follows: 1) when compared to nonoperative management, arthroscopic Bankart repair (ABR) substantially reduces the risk of recurrent dislocations, 2) ABR results in greater shoulder function and higher WOSI scores than does nonoperative management, and 3) despite substantially higher upfront costs, ABR proved to be more cost-effective than an initial trial of nonoperative management, which can be attributed to both fewer recurrent dislocations and greater utility over the long-term.

Objectives: There are few studies that have closely evaluated the outcomes of ulnar collateral ligament repair and reconstruction (UCLR) in position players (PP). The objective of this study was to determine the outcome of UCLR in professional baseball players who play in non-pitcher positions, i.e. PP. Methods: The approval of the Major League Baseball (MLB) Research Committee was obtained. All PP who underwent surgery for their UCL while active on an MLB or Minor League Baseball (MiLB) team were identified using The MLB Health and Injury Tracking System. PP who underwent UCLR from 2010 to 2023 were analyzes, however for data that concerned PP time to return to professional play, only players who underwent UCL surgery from 2010 to 2021 were evaluated in order to ensure the presence of a minimum of 2-year follow-up data. Return to play (RTP) was defined as a player who played in at least 1 game at any professional level (A, AA, AAA, or MLB). Players were deemed to return to the same level of play (RTSLP) if they played in at least 1 game at the same competition level or higher that they played in prior to their UCL surgery. PP who had a time to RTP or a time to RTSLP that exceeded 800 days were excluded from any analysis that concerned the time to return to play. PPs were also compared to a cohort of professional baseball pitchers who had also undergone UCL surgery. Results: From 2010 to 2023, 241 PP underwent surgery for their UCL at a mean age of 23.4 ± 4.3 years old (Table 1). Overall, PP had their UCL surgery at approximately a mean of 3.7 ± 3.3 years after the start of their professional career (Table 1). Further, apart from the year 2020, the annual number of UCL surgeries performed in MLB and MiLB PP demonstrated an upward trend from 2010 to 2023, although no trends in the distribution of UCL surgeries across position type or between major and minor players exist. No statistically significant differences in RTP nor RTSLP rates following UCL surgery in PP existed when comparing across position type (catcher vs. infielder vs. outfielder) and across surgery type (repair vs. reconstruction vs. reconstruction with augmentation) (Table 2). PP who underwent repairs were able to RTP at a median of 221 days (IQR: 81), which was sooner than PP who underwent reconstruction surgery (median: 383 days, IQR: 316) or reconstructions with augmentation (median: 456 days, IQR: 219) (P = 0.002) (Table 3). PP with UCL repairs were also able to RTSLP sooner (median: 234 days, IQR: 64) than PP who underwent reconstructions (median: 394 days, IQR: 305) or reconstructions with augmentation (median: 462 days, IQR: 242) ( P = 0.003) (Table 3). Further, infielders RTP sooner (median: 335 days, IQR: 157) than catchers (median: 396 days, IQR: 283) and outfielders (median: 412 days, IQR: 366) ( P = 0.036) (Table 3). Similarly, infielders RTSLP sooner (median: 334 days, IQR: 162) than catchers (median: 470 days, IQR: 281) and outfielders (median: 426 days, IQR: 354) ( P = 0.016) (Table 3). Following UCL surgery, PP were able to RTSLP, on average, more than 2 months sooner than pitchers (429 ± 177 days for PP vs 499 ± 153 days for pitchers, P < 0.001). PP who underwent repair of their UCL were able to RTSLP over 4.5 months, on average, sooner than pitchers who underwent UCL repair (269 ± 125 days for PPs vs 405 ± 153 days for pitchers, P < 0.001) and PP who underwent reconstruction of their UCL were able to RTSLP just under 50 days sooner than pitchers who had their UCLs reconstructed (450 ± 175 days for PPs vs 498 ± 151 days for pitchers, P < 0.001) (Figure 1). Conclusions: Few studies have examined PP outcome data following UCLR surgery. As such, there is little understanding as to the differences in return to game rates between various baseball non-pitcher positions as well as the differences in the time it takes to RTP and RTSLP. This study highlights that the annual number of UCLR surgeries demonstrates an upward trend. This retrospective analysis also highlights that PP with UCL repairs were able to RTP and RTSLP sooner than PP who underwent UCL reconstructions and UCL reconstructions with augmentation. Furthermore, infielders were able to RTP and RTSLP sooner than catchers as well as outfielders. The results of this study demonstrate that the type of UCL surgery as well as the player’s position does not seem to significantly impact whether or not a player actually returns to playing professional baseball, however it does impact the speed at whichthey are able to return (provided they do return to playing baseball). As such, the results of this study may be used to counsel PP regarding speed at which a return to playing baseball can be expected.

Objectives: The medial ulnar collateral ligament (MUCL) is the primary stabilizer of valgus forces across the elbow. Injury to the MUCL has a large impact on the throwing athlete, particularly in baseball. The incidence of MUCL injury in baseball pitchers is on the rise. Surgical treatment and rehabilitation is evolving to improve outcomes and improve return to sport time frames. The purpose of this study was to highlight the trends in MUCL repair and reconstruction in professional baseball pitchers, describe relevant outcomes such as return to any level of play (RTP) for surgical repair and reconstruction, and distinguish what factors might impact these outcomes. The authors hypothesize that primary and revision MUCL surgery is increasing with revision surgery requiring the greatest time to RTP. Methods: The Major League Baseball (MLB) Health and Injury Tracking System (MLB HITS) database was used to procure data during the targeted study period (2010 – 2023). All professional pitchers who underwent MUCL surgery within the study period were included. Variables analyzed included age, career length, and level of play. Surgical variables included date and type of procedure, RTP status, time required to RTP, return to same level of play (RTSL), career length before and after surgery, number of revision surgeries, and time between surgeries. Successful RTP was designated if a pitcher had returned in at least one professional game after index surgery. Analyses of trends over time were performed. The year 2020 was considered an outlier and omitted from the analysis of trends due to the coronavirus pandemic which limited games played. Results: A total of 2,287 pitchers underwent MUCL surgery during the study period (Table 1). The annual number of MUCL surgeries on all pitchers increased year over year (R 2 = 0.821, p < 0.001), as did the annual number of reconstructions with internal brace (IB) augmentation (R 2 = 0.896, p < 0.001) (Figure 1). The RTP rate (93%) for MLB pitchers was significantly higher compared to the RTSL rate (71%, P < 0.001). This difference was not observed in Minor League Baseball (MiLB) (RTP 76% vs. RTSL 74%, P = 0.142) (Figure 2). The percentage of players who RTP after revision surgery was significantly lower compared to primary surgery (71%vs. 80% respectively, P = 0.020). Mean time to RTP is significantly shorter (470 ± 135 days) compared to the mean time to RTSL (499 ± 153 days, P < 0.001) (Figure 3). The annual number of revision MUCL surgeries on all pitchers increased year over year as well (R 2 = 0.322, p = 0.043). Conclusions: MUCL surgery continues to increase, also leading to increasing numbers of revisions in professional pitchers. Overall, 80% of pitchers were able to RTP at a mean of 470 days (15.5 months), while only 71% were able to RTSL at a mean of 499 days (16.5 months), but this varied based on level of play. Surgical techniques continue to evolve as MUCL repairs and reconstructions with IB augmentation have increased significantly in recent years. This study will help guide athlete expectations and surgeon decision-making.

Background: Treatment decisions in patients with anterior cruciate ligament (ACL) injuries are influenced by multiple factors, such as the desire to return to sports or symptomatic instability. Identifying the differential treatment effect of ACL reconstruction (ACLR) compared with nonoperative management on a patient-specific level can inform surgical decision-making. Hypothesis: Unsupervised machine learning can identify distinct patient subgroups based on outcome achievement after ACL injury, and ACLR will exert a protective effect on the development of posttraumatic osteoarthritis (PTOA) over nonoperative management. Study Design: Cohort study; Level of evidence, 3. Methods: A longitudinal populational registry identified patients with ACL injuries from 1990 to 2016 with a minimum 7.5-year follow-up. An unsupervised random forest algorithm was utilized to develop and validate patient subgroups. Treatment effects of ACLR on outcomes were analyzed using a machine learning causal inference estimator. Patient subgroup membership was incorporated into a multivariable logistic regression to identify factors predictive of optimal outcomes. Results: A total of 923 patients (785 primary ACLR, 138 nonoperative) were included. The random forest algorithm arrived at an optimal partition of 2 subgroups, with 653 patients in the optimal outcome subgroup (368 male [56.4%]; mean age, 26.0 ± 10.2 years; mean body mass index [BMI], 26.5 ± 4.30) and 270 patients in the suboptimal outcome subgroup (152 male [56.3%]; mean age, 35.0 ± 10.1 years; mean BMI, 30.5 ± 5.54). The latter group demonstrated significantly increased rates of secondary meniscal injury, development of symptomatic PTOA, and progression to total knee arthroplasty (TKA) at the final follow-up (all P < .01). In the optimal outcome subgroup, ACLR had significantly protective treatment effects on the risk of secondary meniscal injury (average treatment effect [ATE], 61%), contralateral ACL injury (ATE, 8%), symptomatic PTOA (ATE, 16%), and progression to TKA (ATE, 6%) (all P < .01). Conversely, in the suboptimal outcome subgroup, ACLR only protected against symptomatic PTOA (ATE, 11%) and progression to TKA (ATE, 8%) (both P < .01). Conclusion: Two clinically meaningful subgroups were identified from retrospectively collected data and found to experience differential treatment responses after ACL injuries. ACLR decreased the rate of development of PTOA and TKA in both subgroups but was not as effective in preventing secondary meniscal injuries or contralateral ACL injuries in patients who were older, heavier, or had concomitant medial meniscus injuries.

Background: Injuries of the medial ulnar collateral ligament (MUCL) among baseball pitchers are increasing. Surgical treatment is evolving to optimize outcomes. Purpose/Hypothesis: This study’s purpose was to highlight trends in MUCL repair and reconstruction in professional pitchers, describe outcomes such as return to any level of play (RTP), and identify factors impacting these outcomes. It was hypothesized that primary and revision MUCL surgery is increasing, with revision surgery requiring greater RTP time. Study Design: Case series; Level of evidence, 4. Methods: The Major League Baseball (MLB) Health and Injury Tracking System database was used to procure data during the study period (2010-2023). All professional pitchers who underwent MUCL surgery during this period were included. RTP was defined as a pitcher returning to at least 1 professional game after index surgery. Return to the same level of play (RTSL) was defined as return to at least 1 game in the same league of play as before surgery. Because of the coronavirus pandemic, the year 2020 was considered an outlier and omitted from time-trend analysis. Results: A total of 2281 pitchers who underwent MUCL surgery during the study period were included for analysis. The number of MUCL surgeries for pitchers increased yearly ( R 2 = 0.821; P < .001), as did the number of reconstructions with internal brace augmentation ( R 2 = 0.896; P < .001). The RTP rate for MLB pitchers was significantly higher than the RTSL rate (93% vs 71%; P < .001). This difference was not observed in Minor League Baseball (MiLB) pitchers (RTP 76% vs RTSL 74%; P = .142). RTP rates after revision surgery were lower than those after primary surgery (71% vs 80%; P = .020). The mean time to RTP was shorter (470 ± 135 days) than the mean time to RTSL (499 ± 153 days; P < .001). Conclusion: The incidence of MUCL surgery and revision surgery is increasing among professional pitchers. Overall, 79% of pitchers returned to any level of play at a mean of 470 days, while 74% returned to the same level of play at a mean of 499 days, but this varied based on level of play. This study will guide athlete expectations and surgeon decision-making.

Background: Major League Baseball (MLB) recently instituted a combine for their prospective players. Purpose/Hypothesis: The purpose of this study was to report initial epidemiological findings for both physical examination and imaging findings for the MLB Combine. It was hypothesized that most players would have no significant abnormal physical examination findings, but most would have abnormal findings on their shoulder and elbow magnetic resonance imaging (MRI) scans. Study Design: Descriptive epidemiology study. Methods: All players who attended the 2023 MLB Combine were included. History was taken and physical examination was performed by an MLB team physician, and MRI of the shoulder, elbow, cervical spine, and lumbar spine was performed on all players and read by 1 of 2 musculoskeletal radiologists. Physical examination notes and imaging reports were reviewed by the authors and recorded. Data were analyzed separately for pitchers and position players. Results: Overall, 219 players (112 pitchers [51%], 107 position players [49%]) were included. The mean age was 20.4 ± 1.5 years. The majority of players (95%) had no current pain or limitations; 54 players (25%) had a history of previous surgery. For pitchers, 18% underwent previous elbow surgery. With regard to MRI, >80% of pitchers had some abnormality within their ulnar collateral ligament (UCL), the majority of which was UCL scarring/remodeling. 70% of pitchers and 60% of position players had evidence of an olecranon osteophyte. Increased signal within the ulnar nerve was common in pitchers (40%) but rare in position players (4%). For the shoulder, 95% of pitchers and 93% of position players had some rotator cuff abnormality (often tendinosis within the supraspinatus and infraspinatus muscles). Also, 75% of pitchers had MRI evidence of a superior labrum anterior to posterior (SLAP) tear, while 24% of position players demonstrated this. Lumbar spine MRI showed that 47% of position players had a disk protrusion and 46% had a previous pars fracture. Conclusion: Most baseball players who participated in the 2023 MLB Combine had MRI evidence of rotator cuff abnormalities, and many showed evidence of an olecranon osteophyte. Eighteen percent of pitchers had a previous history of elbow surgery. The majority of pitchers had some abnormality within their UCL and evidence of a SLAP tear on MRI scans.

Context: There is need for an up-to-date comprehensive review of baseball interval throwing programs in the literature. Objective: To (1) understand the origin and basis of interval throwing programs; (2) evaluate the content of programs in the peer-reviewed literature including target audience, initiation criteria, throwing specifics, arm care, and performance evaluation metrics; (3) classify these variables as well defined, ambiguous, or missing; and (4) analyze variability in key aspects including starting criteria, length, progression, and completion criteria. Data Sources: Medline, Embase, Cochrane Reviews, Web of Science, and Scopus Study Selection: The full text of studies, in English, had to be available. Included studies had to contain a complete interval throwing program designed for baseball players. Study Design: Systematic review. Level of Evidence: Level 4. Data Extraction: Initial screening was conducted based on article title and abstract. Full text of the remaining articles was evaluated for fulfillment of inclusion criteria. Results: Nine studies initially met inclusion criteria. The programs’ comprehensiveness was poor, with a mean Interval Throwing Program Checklist score of 20 (range 14-23) on a scale of 0 to 30. There were a variety of components, including progressive long toss, weighted ball, and throwing mechanics exercises. The programs identified had significant heterogeneity in duration, intensity, progression, and focus. Overall, there was a significant lack of attempts at validation or formal study of efficacy for published throwing programs. Conclusion: Current published interval throwing programs are mostly variations of an original program published many years ago and were based on principles of progressive loading with pain as sign of injury that should be monitored carefully. However, these programs have minimal clinical validation and objective measures to quantify their effectiveness. This work identifies several limitations in the current literature and can serve as a foundation for future development of evidence-based interval throwing programs.

Background: Nonoperative and operative management techniques after anterior cruciate ligament (ACL) injury are both appropriate treatment options for selected patients. However, the subsequent development of posttraumatic knee osteoarthritis (PTOA) remains an area of active study. Purpose: To compare the risk of PTOA between patients treated without surgery and with ACL reconstruction (ACLR) after primary ACL disruption using a machine learning causal inference model. Study Design: Cohort study; Level of evidence, 3. Methods: A geographic database identified patients undergoing ACLR between 1990 and 2016 with minimum 7.5-year follow-up. Variables collected include age, sex, body mass index, activity level, occupation, relevant comorbid diagnoses, radiographic findings, injury characteristics, and clinical course. Treatment effects of ACLR on the development of PTOA and progression to total knee arthroplasty (TKA) were analyzed with machine learning models (MLMs) in a causal inference estimator (targeted maximum likelihood estimation, TMLE), while controlling for confounders. Results: The study included 1194 patients with a minimum follow-up of 7.5 years, among whom 974 underwent primary reconstruction and 220 underwent nonoperative treatment. A total of 215 (22%) patients developed symptomatic PTOA in the ACLR group compared with 140 (64%) in the nonoperative treatment group ( P < .001), whereas 25 (3%) patients underwent TKA in the ACLR group compared with 50 (23%) in the nonoperative treatment group ( P < .001). Patients in the ACLR group had delayed TKA compared with patients in the nonoperative treatment group (193.4 vs 166.0 months, respectively; P = .02). TMLE evaluation revealed that reconstruction decreased the risk of PTOA by 11% (95% CI, 8%-13%; P < .001) compared with nonoperative treatment but did not demonstrate a significant effect on the rate of progression to TKA. Survival analysis with random forest algorithm demonstrated significant delay to the onset of PTOA as well as time to progression of TKA in patients undergoing ACLR. Additional risk factors for the development of PTOA, irrespective of treatment, included older age at injury, greater body mass index, total number of arthroscopic knee surgeries, and residual laxity at follow-up. Conclusion: MLMs in a causal inference estimator found ACLR to exert a significant treatment effect in reducing the rate of development of PTOA by 11% compared with nonoperative treatment. ACLR also delayed the onset of PTOA and progression to TKA.