Superior 2-Year Functional Outcomes Among Young Female Athletes After ACL Reconstruction in 10 Return-to-Sport Training Sessions: Comparison of ACL-SPORTS Randomized Controlled Trial With Delaware-Oslo and MOON Cohorts

Functional Return-to-Sport Testing Demonstrates Inconsistency in Predicting Short-Term Outcomes Following Anterior Cruciate Ligament Reconstruction: A Systematic Review

PURPOSE

To systematically review the relationship between functional testing at the time of return to sport (RTS) and short-term outcomes, such as second anterior cruciate ligament (ACL) tear and return to a preinjury level of sport, among athletes who underwent anterior cruciate ligament reconstruction (ACLR).

METHODS

A systematic literature search was performed in MEDLINE, EMBASE, Scopus, and Web of Science to identify studies examining athletes who underwent functional RTS testing and were followed for at least 12 months following ACLR. Studies were screened by 2 reviewers. A standardized template was used to extract information regarding study characteristics, ACLR information, functional test results, and risk factors associated with retear or reduced RTS.

RESULTS

Of the 937 studies identified, 22 met the inclusion criteria. The average time between ACLR and RTS testing was 8.5 months. Single leg hop for distance performance had no association with retear risk in any study and no association with RTS rates in most studies. Quadriceps strength had conflicting results in relation to retear risk, whereas it had no relationship with RTS rates. Rates of reinjury and RTS were similar between patients who passed and did not pass combined hop and strength batteries. Asymmetric knee extension and hip moments, along with increased knee valgus and knee flexion angles, demonstrated increased risk of retear.

CONCLUSIONS

Individual hop and strength tests that are often used in RTS protocols following ACLR may have limited and inconsistent value in predicting ACL reinjury and reduced RTS when used in isolation. Combined hop and strength test batteries also demonstrate low sensitivity and negative predictive value, highlighting conflicting evidence to suggest RTS testing algorithm superiority.

LEVEL OF EVIDENCE

Level IV, systematic review of Level I-IV studies.

Global knee function rating more strongly influences adolescent athletes that sustain a sports-related surgical ACL re-injury or contralateral ACL injury

PURPOSE

This study evaluated differences between adolescent athletes who sustained a surgical anterior cruciate ligament (ACL) re-injury, or contralateral ACL injury following return to sports bridge programme participation (Group 1) compared to those that did not (Group 2).

METHODS

At 19.9 ± 7 years of age, 198 athletes participated in this study. Groups were compared for time postsurgery, preprogramme and postprogramme Knee Outcome Survey Sports Activity Scale (KOS-SAS) and global rating of knee function (GRKF) during sports activities, postprogramme lower extremity physical function test performance and perceived sports performance compared to preinjury level.

RESULTS

By 6.0 ± 3.2 years postsurgery, 11 (5.6%) sustained another ACL injury. Group 1 was younger (17.3 ± 1.7 years vs. 20.1 ± 6.8 years, p < 0.001). Postprogramme re-evaluation revealed that Group 1 had a greater GRKF compared to their programme initiation GRKF than Group 2 (32.6 ± 38 vs. 20.0 ± 23, p = 0.04). Group 1 also had a greater mean preprogramme to postprogramme GRKF change than Group 2 (51.3 ± 31 vs. 35.5 ± 21, p = 0.02) (effect size = 0.73). More Group 1 subjects also had a GRKF difference that exceeded the overall mean than Group 2 (p = 0.04). Group 1 had moderately strong relationships between preprogramme and postprogramme GRKF score change and the postprogramme GRKF score (r = 0.65, p = 0.04) and between preprogramme and postprogramme KOS-SAS score change and postprogramme GRKF score (r = 0.60, p = 0.04).

CONCLUSION

Global rating scores had a stronger influence among adolescent athletes that sustained either surgical ACL re-injury or contralateral ACL injury. Since group physical function and neuromuscular control factors were similar, clinicians need to increase their awareness and understanding of other factors that may influence surgical ACL re-injury or contralateral ACL injury risk.

LEVEL OF EVIDENCE

Level III, retrospective cohort study.

A clinical practice review of therapeutic movement-based anterior cruciate ligament reconstruction return to sports bridge program: the biological, biomechanical and behavioral rationale

This clinical practice review describes the biological, biomechanical and behavioral rationale behind a return to sport bridge program used predominantly with non-elite, youth and adolescent high school and college athletes following anterior cruciate ligament (ACL) reconstruction. Post-physiotherapy, this program has produced outcomes that meet or exceed previous reports. With consideration for athletic identity and the Specific Adaptations to Imposed Demands (SAID) principle, the early program focus was on restoring non-impaired bilateral lower extremity joint mobility and bi-articular musculotendinous extensibility. Building on this foundation, movement training education, fundamental bilateral lower extremity strength and power, and motor learning was emphasized with use of external focus cues and ecological dynamics-social cognition considerations. Plyometric and agility tasks were integrated to enhance fast twitch muscle fiber recruitment, anaerobic metabolic energy system function, and fatigue resistance. The ultimate goal was to achieve the lower extremity neuromuscular control and activation responsiveness needed for bilateral dynamic knee joint stability. The rationale and conceptual basis of selected movement tasks and general philosophy of care concepts are described and discussed in detail. Based on the previously reported efficacy of this movement-based therapeutic exercise program we recommend that supplemental programs such as this become standard practice following release from post-surgical physiotherapy and before return to sports decision-making.

Secondary Anterior Cruciate Ligament Injury Prevention Training in Athletes: What Is the Missing Link?

After reconstruction, the return to full competition rate of athletes is low, while the re-injury rate remains high despite the completion of a rehabilitation programme. Primary ACL prevention programmes are well developed, yet few research papers focus on secondary ACL injury prevention. The aim of current review is to determine if current ACL secondary prevention training has a positive influence on the re-injury rate, the clinical or functional outcomes, or the risk of re-injury in athletes. Studies investigating secondary prevention of ACL were searched in PubMed and EBSCOhost, followed by a review of the references in the identified articles. The existing evidence suggests that neuromuscular training, eccentric strengthening, and plyometric exercises may have a potential impact on improving biomechanical, functional, and psychological outcomes in athletes; however, the studies on the prevention of second ACL injury in athletes is scarce and inconclusive. Future research is needed to investigate the effectiveness of secondary ACL prevention in reducing the re-injury rates. (PROSPERO Registration number: CRD42021291308).

Interventions for increasing return to sport rates after an anterior cruciate ligament reconstruction surgery: A systematic review

Background

An injury followed by surgery poses many challenges to an athlete, one of which is rehabilitation, with the goal of returning to sport. While total restoration of physical abilities is a primary goal for most athletes, psychosocial factors also play an important role in the success of an athlete's return to sport (RTS). The purpose of this review was to examine the effectiveness of exercise and psychosocial interventions on RTS rates, which might be one of the most important outcomes for elite athletes.

Methods

To carry out this review, PubMed, SAGE Journals, Web of Science, SPORTDiscus, ScienceDirect, and Google Scholar databases were searched from inception to July 2022. The inclusion criteria consisted exercise or psychosocial intervention for athletes after anterior cruciate ligament reconstruction (ACLR), with reporting RTS rates as an outcome.

Results

From 1032 identified articles, four reports (N = 130) met inclusion criteria, all of which examined the recovery after ACLR. The mean MINORS score for the included studies was 16.3 ± 6.1, of which non-comparative studies scored 11.0 ± 1.4, while comparative studies scored 21.5 ± 0.7. There were consistent findings for benefits of exercise and psychosocial interventions on RTS rates. Return to preinjury rates in the reviewed studies vary between 63 and 95% with lower % observed in female athletes and with shorter follow-up. Interventional studies reporting RTS rates with a larger sample size and longer follow-up are needed.

Conclusion

Physical and psychological function, as well as social support can be influenced by appropriate interventions, indicating future work on rehabilitation programs for return to preinjury might consider taking the holistic approach addressing those.

Advanced training enhances readiness to return to sport after anterior cruciate ligament reconstruction

Patients with anterior cruciate ligament reconstruction (ACLR) are often psychologically and physically under-prepared for sports participation. This study compared readiness to return to sport based on completion of advanced training after ACLR. Patients with ACLR who self-selected participation in a 6-week group-format advanced training program (TRAINING) were compared to age- and sex-matched patients who did not participate (NoTRAINING). Each group had 23 participants (14 females). Advanced training consisted of plyometric, strengthening, and agility exercises. Baseline and follow-up testing included psychological measures (Anterior Cruciate Ligament Return to Sport after Injury [ACL-RSI]; Tampa Scale for Kinesiophobia [TSK-11]; Knee Activity Self-Efficacy [KASE]; and fear intensity for the primary fear-evoking task or situation) and a hop test battery. Return to sport criteria were ACL-RSI score ≥70 points and limb symmetry index ≥90% on all hop tests. At follow-up, KASE score was higher in TRAINING than NoTRAINING (92.7 vs. 89.1 points; respectively), but ACL-RSI, TSK-11 and fear intensity scores were not significantly different between groups. Return to sport criteria passing rate was not significantly different between groups at baseline (TRAINING: 13%, NoTRAINING: 30%) or follow-up (TRAINING: 52%, NoTRAINING: 43%); however, the distribution of criteria met at follow-up differed with more patients in TRAINING than NoTRAINING meeting hop test criteria (30% vs. 4%, respectively) and more patients in NoTRAINING than TRAINING failing to meet any criteria (25% vs. 0%, respectively). Advanced training after ACLR facilitated readiness for sport participation by improving confidence and hop performance, but may not have a preferential effect on fear.

Unique Considerations for the Pediatric Athlete During Rehabilitation and Return to Sport After Anterior Cruciate Ligament Reconstruction

Anterior cruciate ligament (ACL) injuries and surgical intervention in the pediatric population have increased in the recent years. Although surgical techniques have advanced, evidence-based rehabilitation guidelines that consider all aspects of the youth athlete are currently lacking. The purpose of this commentary is to review the current evidence on unique considerations for the pediatric and adolescent population during rehabilitation and return to sport after ACL reconstruction (ACLR), with a focus on children under 18 years of age. This review revealed that returning a youth athlete to sport after ACLR requires knowledge and appreciation of various aspects of the growing athlete different from adults. In addition to postoperative precautions that contribute to a slow rehabilitation process, young athletes need additional time for strength gains. Address risk of reinjury and for contralateral injury by using neuromuscular training and rigorous return-to-sport training programs. Consider return to sport after 9 months because the reinjury rate is high in this population. A combination of time and objective measures, both quantitative and qualitative criteria, and psychological readiness should be used to assess readiness to return to sport and decrease risk of future injury. Healthcare providers should be aware of the psychosocial impact of injury on the youth athletes and refer to sport psychology when necessary.

LEVEL OF EVIDENCE

Level V.

ACL Reconstruction Rehabilitation: Clinical Data, Biologic Healing, and Criterion-Based Milestones to Inform a Return-to-Sport Guideline

CONTEXT

Anterior cruciate ligament (ACL) reconstruction (ACLR) and postoperative rehabilitation continues to be a multidisciplinary focus in both research and clinical environments. Recent research on ACLR warrants a reexamination of clinicians' current rehabilitation practices to optimize the strikingly variable clinical outcomes after ACLR and return to sport. The purpose of the article and updated guidelines is to use contemporary evidence to systematically revisit our practice guidelines and validate our clinical milestones with data from our university-based practice.

EVIDENCE ACQUISITION

Using the PubMed search engine, articles that reported on ACLR rehabilitation and protocols, guidelines, graft type, healing and strain, return to sport, psychological considerations, and secondary injury prevention published from 1979 to 2020 were identified using the search terms ACLR protocols, guidelines, ACLR rehabilitation, ACL graft, ACL open kinetic chain (OKC) exercise and closed kinetic chain (CKC) exercise, ACLR return to sport, ACLR psychological factors, and ACL injury prevention.

STUDY DESIGN

Clinical review.

LEVEL OF EVIDENCE

Level 5.

RESULTS

Clinical milestones after ACLR were validated using clinical data collected from 2013 to 2017 at a university-based practice. Variables including knee joint range of motion, effusion, Knee Outcome Survey-Activities of Daily Living Scale, and quadriceps strength index were tracked throughout rehabilitation and analyzed to help inform an updated ACLR rehabilitation guideline.

CONCLUSION

Incorporating the latest research, combined with direct clinical data, provides a current, realistic, and clinically benchmarked strategy for ACLR rehabilitation. Commonly held clinical beliefs regarding rehabilitation after ACL injury must be challenged by the latest research to improve patient outcomes and decrease the risk of reinjury. Key updates to the practice guidelines include the use of frequent and accurate quadriceps strength testing, delayed return-to-sport timeline, immediate use of open kinetic chain exercise, criterion-based progressions for running, sprinting, plyometrics, agility, cutting/pivoting, return to competition, and the inclusion of a secondary prevention program after return to sport.

STRENGTH OF RECOMMENDATION TAXONOMY (SORT)

B.

The Minimally Clinically Important Difference and Substantial Clinical Benefit in Anterior Cruciate Ligament Reconstruction: A Time-to-Achievement Analysis

This study examined the time-dependent course of the minimally clinically important difference (MCID) and the substantial clinical benefit (SCB) achievement for International Knee Documentation Committee (IKDC) and Knee Injury and Osteoarthritis Outcome Score (KOOS) subscales following anterior cruciate ligament reconstruction (ACLR). A prospective institutional registry was queried for patients receiving ACLR. The patient-reported outcome measures (PROMs) of interest included the IKDC score and KOOS sub-scales. One hundred forty-three patients (mean±SD age, 30.86±12.78 years; mean±SD body mass index, 25.51±4.64 kg/m²) were included in the analysis. Threshold values for the MCID/SCB were 18.9 of 29.6 on IKDC score, 15.7 of 25.3 on KOOS Symptom, 11.9 of 15.5 on KOOS Pain, 13.3 of 20.0 on KOOS ADL, 25.9 of 35.8 on KOOS Quality of Life (QoL), and 27.0 of 43.0 on KOOS Sport (area under the curve, 0.74-0.91). Overall, MCID achievement rates increased from 28.0% to 42.7% at 6 months to 41.9% to 70.8% at 12 months. Achievement rates of SCB increased from 16.1% to 30.4% at 6 months to 29.3% to 51.8% at 12 months. Statistically significant increases in MCID achievement (chi-square=47.95-79.36, all P<.001) and SCB achievement (chi-square=26.02-53.24, all P<.001) occurred from preoperative to 6-month time points across PROMs. From 6-month to 12-month time points, increases in MCID achievement occurred on IKDC score and KOOS QoL (chi-square=5.53-15.11, P<.001-.009). Statistically significant increases in MCID and SCB achievement occurred from preoperative to 6-month time points across IKDC score and KOOS subscales; however, statistically significant increases in achievement rates from 6 months to 1 year occurred on IKDC score, KOOS QoL, and KOOS Sport. This study underlines the importance of considering psychological factors and rehabilitative milestones when examining the achievement MCID and SCB after ACLR. [Orthopedics. 2021;44(5):299-305.].

Safety and Effectiveness of a Perturbation-based Neuromuscular Training Program on Dynamic Balance in Adolescent Females: A Randomized Controlled Trial

BACKGROUND

Adolescent females are at much greater risk for ACL injury than their male counterparts when participating in the same sports. Preventative and pre-operative rehabilitation neuromuscular (NM) exercise programs are often recommended to improve knee function and reduce injury rates. The effectiveness of perturbation-based NM training program has been established in an adult population but has yet to be investigated in the at-risk adolescent female population.

PURPOSE

To determine the effectiveness of a perturbation-based NM exercise program in a group of physically active adolescent females.

STUDY DESIGN

Prospective randomized trial.

METHODS

Twenty-four healthy and an exploratory group of 10 ACL-injured females (ages 12-18) were equally randomized into a perturbation-based NM training or control group and evaluated before and after a five-week intervention period. The primary outcome of dynamic balance was measured using the Y-Balance test (YBT); secondary outcome measures included lower limb strength, proprioception, and flexibility.

RESULTS

The perturbation-based NM training intervention was safely completed by all participants but had no significant effect on YBT scoring, lower limb strength, proprioception or flexibility in either the healthy or ACL-injured groups.

CONCLUSIONS

Perturbation-based NM training is safe, but may offer little preventative benefit for healthy or pre-operative rehabilitation benefit for ACL-injured adolescent females. Future research should examine whether the effectiveness of perturbation-based NM training is influenced by the length of the training intervention, training intensity, or when it is combined with other forms of prophylactic or pre-surgical rehabilitation frequently used with at-risk adolescent females who regularly participate in sport.

LEVEL OF EVIDENCE

Level 3.

Secondary Injuries After Pediatric Anterior Cruciate Ligament Reconstruction: A Systematic Review With Quantitative Analysis

BACKGROUND

In the skeletally mature anterior cruciate ligament (ACL) reconstruction population, patients aged <25 years are at significantly increased risk of graft failure and injury to the contralateral ACL. Skeletal immaturity often affects graft selection and reconstruction technique.

PURPOSE

To examine the incidence of ipsilateral graft failure and contralateral ACL injury in the skeletally immature patient population.

STUDY DESIGN

Systematic review and meta-analysis.

METHODS

Using the PRISMA (Preferred Reporting Items for Systematic Meta-Analyses) guidelines, we reviewed all literature that involved ACL reconstruction performed on skeletally immature patients between May 1976 and May 2019. Patient demographics, surgical technique, and the prevalence of ipsilateral graft failure or subsequent contralateral ACL injury were recorded. Ipsilateral, contralateral, and secondary ACL injuries were then compared between sexes via chi-square tests.

RESULTS

A total of 24 articles (1254 children; 1258 knees) met inclusion criteria for analysis. Ipsilateral graft failures occurred in 105 of 1258 patients (8.3%), and there were no statistically significant sex differences in the prevalence of graft failures (female, 9.7%; male patients, 7.1%; P = .14). The prevalence of contralateral ACL injury was significantly greater in female (29/129; 22.5%) than male (18/206; 8.7%; P = .0004) patients in the 9 studies that reported contralateral injury. Skeletally immature female patients were at significantly increased risk of contralateral ACL injury (odds ratio = 3.0; P = .0006) when compared with their male counterparts.

CONCLUSION

In the literature to date, 1 in 3 female skeletally immature patients experienced an ipsilateral graft failure or contralateral ACL injury. Regardless of sex, the 24% prevalence of secondary injury after pediatric ACL reconstruction is almost identical to previously published secondary injury rates in skeletally mature patients <25 years old. As such, skeletal maturity alone does not seem to be a determinant of secondary injury; however, there is a clear need to improve postoperative rehabilitation, activity progression, and return-to-play testing to allow a safe return to sports that protects the long-term health of the reconstructed and contralateral limbs, especially for female patients.

Quadriceps Strength Symmetry Does Not Modify Gait Mechanics After Anterior Cruciate Ligament Reconstruction, Rehabilitation, and Return-to-Sport Training

BACKGROUND

After anterior cruciate ligament (ACL) reconstruction (ACLR), biomechanical asymmetries during gait are highly prevalent, persistent, and linked to posttraumatic knee osteoarthritis. Quadriceps strength is an important clinical measure associated with preoperative gait asymmetries and postoperative function and is a primary criterion for return-to-sport clearance. Evidence relating symmetry in quadriceps strength with gait biomechanics is limited to preoperative and early rehabilitation time points before return-to-sport training.

PURPOSE/HYPOTHESIS

The purpose was to determine the relationship between symmetry in isometric quadriceps strength and gait biomechanics after return-to-sport training in athletes after ACLR. We hypothesized that as quadriceps strength symmetry increases, athletes will demonstrate more symmetric knee joint biomechanics, including tibiofemoral joint loading during gait.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

Of 79 athletes enrolled in the ACL-SPORTS Trial, 76 were participants in this study after completing postoperative rehabilitation and 10 return-to-sport training sessions (mean ± SD, 7.1 ± 2.0 months after ACLR). All participants completed biomechanical walking gait analysis and isometric quadriceps strength assessment using an electromechanical dynamometer. Quadriceps strength was calculated using a limb symmetry index (involved limb value / uninvolved limb value × 100). The biomechanical variables of interest included peak knee flexion angle, peak knee internal extension moment, sagittal plane knee excursion at weight acceptance and midstance, quadriceps muscle force at peak knee flexion angle, and peak medial compartment contact force. Spearman rank correlation (ρ) coefficients were used to determine the relationship between limb symmetry indexes in quadriceps strength and each biomechanical variable; alpha was set to .05.

RESULTS

Of the 76 participants, 27 (35%) demonstrated asymmetries in quadriceps strength, defined by quadriceps strength symmetry <90% (n = 23) or >110% (n = 4) (range, 56.9%-131.7%). For the biomechanical variables of interest, 67% demonstrated asymmetry in peak knee flexion angle; 68% and 83% in knee excursion during weight acceptance and midstance, respectively; 74% in internal peak knee extension moment; 57% in medial compartment contact force; and 74% in quadriceps muscle force. There were no significant correlations between quadriceps strength index and limb symmetry indexes for any biomechanical variable after return-to-sport training (P > .129).

CONCLUSION

Among those who completed return-to-sport training after ACLR, subsequent quadriceps strength symmetry was not correlated with the persistent asymmetries in gait biomechanics. After a threshold of quadriceps strength is reached, restoring strength alone may not ameliorate gait asymmetries, and current clinical interventions and return-to-sport training may not adequately target gait.

Return to sports bridge program improves outcomes, decreases ipsilateral knee re-injury and contralateral knee injury rates post-ACL reconstruction

PURPOSE

To present the results of a return to sports bridge program designed to reduce knee injuries following ACL reconstruction and physical therapy.

METHODS

One hundred and fifty (male = 83, female = 67) patients participated in a whole body neuromuscular control, progressive resistance strength and agility training program. Post-program testing included functional movement form, dynamic knee stability, lower extremity power, agility, and sports skill assessments. Participants completed the Knee Outcome Survey-Sports Activity Scale (KOS-SAS) before and after program initiation. Pre-participation scores were re-estimated following program completion.

RESULTS

Global rating KOS-SAS score at program entry was 75 ± 13. Post-program global rating and calculated KOS-SAS were 91.0 ± 9.8 and 90.9 ± 9.7, respectively (p < 0.0001). Pre-participation KOS-SAS score re-estimates at program completion were 54.5 ± 23.3 and 57.3 ± 18.5, respectively. The approximately 20% lower pre-program KOS-SAS score re-estimates (p < 0.0001) observed at program completion suggests that subjects had inaccurately high sports readiness perceptions at program entry. Perceived overall sports activity knee function ratings improved from 2.9 ± 0.6 (abnormal) at program entry to 1.3 ± 0.5 (normal) at completion (p < 0.0001). Most subjects returned back to sports at or above their pre-injury performance skill/performance level (84%, 126/150). By 6.8 ± 3.2 years (range = 2-13 years) post-surgery, ten subjects had sustained an ipsilateral knee re-injury or contralateral knee injury (6.7%). The 2.7% non-contact contralateral and 1.3% non-contact ipsilateral knee injury rates observed were significantly lower than those cited in previous reports.

CONCLUSION

Supplementing primary ACL reconstruction and standard physical therapy with a return to sports bridge program prior to release to unrestricted sports performance was effective at improving patient outcomes and decreasing ipsilateral knee re-injury and contralateral knee injury rates.

LEVEL OF EVIDENCE

II.

FUNCTIONAL MEASURES DO NOT DIFFER IN LATE STAGE REHABILITATION AFTER ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION ACCORDING TO MECHANISM OF INJURY

Background

Anterior cruciate ligament injuries are among the most common knee injuries. Mechanism of injury is classified as contact or non-contact. The majority of anterior cruciate ligament ruptures occur through a non-contact mechanism of injury. Non-contact anterior cruciate ligament ruptures are associated with biomechanical and neuromuscular risk factors that can predispose athletes to injuries and may impact future function. Non-contact mechanism of injury may be preceded by poor dynamic knee stability and therefore those with a non-contact mechanism of injury may be prone to poor dynamic knee stability post-operatively. Understanding how mechanism of injury affects post-operative functional recovery may have clinical implications on rehabilitation.

Purpose

The purpose of this study was to determine if mechanism of injury influenced strength, functional performance, patient-reported outcome measures, and psychological outlook in athletes at four time points in the first two years following anterior cruciate ligament reconstruction.

Study Design

Secondary analysis of a clinical trial.

Methods

Seventy-nine athletes underwent functional testing at enrollment after impairment resolution. Quadriceps strength, hop testing, and patient-reported outcome measures were evaluated post-operatively at enrollment, following return-to-sport training and one year and two years after anterior cruciate ligament reconstruction. Participants were dichotomized by mechanism of injury (29 contact, 50 noncontact). Independent t-tests were used to compare differences between groups.

Results

There were no meaningful differences between contact and non-contact mechanism of injury in any variables at enrollment, post-training, one year, or two years after anterior cruciate ligament reconstruction.

Conclusion

Function did not differ according to mechanism of injury during late stage rehabilitation or one or two years after anterior cruciate ligament reconstruction.

Level of Evidence

III.

A Secondary Injury Prevention Program May Decrease Contralateral Anterior Cruciate Ligament Injuries in Female Athletes: 2-Year Injury Rates in the ACL-SPORTS Randomized Controlled Trial

OBJECTIVE

To determine whether the addition of perturbation training to a secondary injury prevention program reduces the rate of second anterior cruciate ligament (ACL) injury compared to the prevention program alone.

DESIGN

Single-blinded randomized controlled trial.

METHODS

Thirty-nine female athletes who intended to return to cutting/pivoting sports were enrolled 3 to 9 months after primary anterior cruciate ligament reconstruction (ACLR). Athletes were randomized to receive a training program of either progressive strengthening, agility, plyometrics, and prevention (SAPP) (n = 20) or SAPP plus perturbation training (n = 19); each had 10 sessions over 5 weeks. Occurrence and side of second ACL injury were recorded for 2 years after primary ACLR.

RESULTS

There were 9 second ACL injuries in the 2 years after ACLR. There was no statistically significant difference in rate or side of second ACL injury between the SAPP-plus-perturbation training and SAPP groups.

CONCLUSION

Adding perturbation training to a secondary ACL injury prevention program did not affect the rate of second ACL injury in female athletes. J Orthop Sports Phys Ther 2020;50(9):523-530. Epub 1 Aug 2020. doi:10.2519/jospt.2020.9407.

Biomechanical effects of manipulating peak vertical ground reaction force throughout gait in individuals 6-12 months after anterior cruciate ligament reconstruction

BACKGROUND

We aimed to determine the effect of cueing an increase or decrease in the vertical ground reaction force impact peak (peak in the first 50% of stance) on vertical ground reaction force, knee flexion angle, internal knee extension moment, and internal knee abduction moment waveforms throughout stance in individuals 6-12 months after an anterior cruciate ligament reconstruction.

METHODS

Twelve individuals completed 3 conditions (High, Low, and Control) where High and Low Conditions cue a 5% body weight increase or decrease, respectively, in the vertical ground reaction force impact peak compared to usual walking. Biomechanics during High and Low Conditions were compared to the Control Condition throughout stance.

FINDINGS

The High Condition resulted in: (a) increased vertical ground reaction forces at each peak and decreased during mid-stance, (b) greater knee excursion (i.e., greater knee flexion angle in early stance and a more extended knee in late stance), (c) greater internal extension moment for the majority of stance, and (d) lesser second internal knee abduction moment peak. The Low Condition resulted in: (a) vertical ground reaction forces decreased during early stance and increased during mid-stance, (b) decreased knee excursion, (c) increased internal extension moment throughout stance, and (d) decreased internal knee abduction moment peaks.

INTERPRETATION

Cueing a 5% body weight increase in vertical ground reaction force impact peak resulted in a more dynamic vertical ground reaction force loading pattern, increased knee excursion, and a greater internal extension moment during stance which may be useful in restoring gait patterns following anterior cruciate ligament reconstruction.

Streamlining the KOOS Activities of Daily Living Subscale Using Machine Learning

Background:

Functional outcome scores provide valuable data, yet they can be burdensome to patients and require significant resources to administer. The Knee injury and Osteoarthritis Outcome Score (KOOS) is a knee-specific patient-reported outcome measure (PROM) and is validated for anterior cruciate ligament (ACL) reconstruction outcomes. The KOOS requires 42 questions in 5 subscales. We utilized a machine learning (ML) algorithm to determine whether the number of questions and the resultant burden to complete the survey can be lowered in a subset (activities of daily living; ADL) of KOOS, yet still provide identical data.

Hypothesis:

Fewer questions than the 17 currently provided are actually needed to predict KOOS ADL subscale scores with high accuracy.

Study Design:

Cohort study (diagnosis); Level of evidence, 2.

Methods:

Pre- and postoperative patient-reported KOOS ADL scores were obtained from the Surgical Outcome System (SOS) data registry for patients who had ACL reconstruction. Categorical Boosting (CatBoost) ML models were built to analyze each question and its value in predicting the patient’s actual functional outcome (ie, KOOS ADL score). A streamlined set of minimal essential questions were then identified.

Results:

The SOS registry contained 6185 patients who underwent ACL reconstruction. A total of 2525 patients between the age of 16 and 50 years had completed KOOS ADL scores presurgically and 3 months postoperatively. The data set consisted of 51.84% male patients and 48.16% female patients, with a mean age of 29 years. The CatBoost model predicted KOOS ADL scores with high accuracy when only 6 questions were asked (R² = 0.95), similar to when all 17 questions of the subscale were asked (R² = 0.99).

Conclusion:

ML algorithms successfully identified the essential questions in the KOOS ADL questionnaire. Only 35% (6/17) of KOOS ADL questions (descending stairs, ascending stairs, standing, walking on flat surface, putting on socks/stockings, and getting on/off toilet) are needed to predict KOOS ADL scores with high accuracy after ACL reconstruction. ML can be utilized successfully to streamline the burden of patient data collection. This, in turn, can potentially lead to improved patient reporting, increased compliance, and increased utilization of PROMs while still providing quality data.