Research Review: Immediate Effects of Real-Time Feedback on Jump-Landing Kinematics

In the next instalment of the Research Review Series, we discuss the impact of real-time feedback in addition to post-response feedback compared to post-response feedback alone on jumping-landing mechanics in a young female population1

Study Design

Randomized controlled trial.


Thirty-six pain-free females were recruited from the general student population at the University of Toledo and assigned to either the real-time feedback (RTF), RTF plus post-response feed-back (RTF+), or the no feedback control group (CG).

Inclusion Criteria: (1) Female gender, (2) No current or previous lower extremity musculoskeletal complaints

Exclusion Criteria: (1) Male gender, (2) previous history of fracture, surgery, or significant orthopaedic injury to the lower extremity


Outcome Measures: Kinematic and kinetic data were collected as participants performed 3 trials of a jump-landing task from a 30-cm box, positioned at a horizontal distance of 50% of the participant’s height from 2 force platforms. Sagittal plane moments and angles at the knee and hip, frontal plane angles at the knee, and vertical ground reaction forces during the jump-landing task were quantified at baseline and post-intervention.

Randomization: Block randomization was used with concealed allocation to assign participants to 1 of the 3 groups. An opaque envelope was used to conceal group assignment until after baseline testing.

Interventions: Prior to the intervention, both the RTF+ and PRF feedback groups were presented with a PowerPoint presentation explaining the goals of the jump-landing task. This presentation outlined the need to (1) land with both feet at the same time, (2) land in neutral valgus/varus position, (3) land with feet shoulder width apart, (4) land on toes and rock onto heels, (5) land with increased bending at the knees and hips, and (6) land softly. After viewing the presentation, participants in both intervention groups performed 3 sets of 6 jumps from the box. Following each set of 6 jumps, the investigator reviewed the goals that the participant failed to accomplish in the previous jumps and showed the participant the corresponding PowerPoint slides to reinforce the correct form.

For the RTF+ group, participants received a live, digital representation of their body segments and were able to see a reference line to assist in making biomechanical corrections in the frontal plane. The RTF+ group was provided the following explanation,

You will now be able to see markers representing your knee and toe on the screen in real time; start with your toe marker in line with the reference line and then line your knee marker up with the reference line. This is the way the markers should line up when you land; we want you to watch the video monitor, focusing on keeping the shank segment in line with the reference line when you land from your jump. You can aim to land with your foot on the tape line, but your main focus should be to keep the shank segment lined up with the line when landing from the jump.

Participants in the no-feedback control group performed the same jump landing sequence as the other two groups, however they received no feedback or PowerPoint presentation on the major goals of jump landing.


Post hoc testing revealed that the RTF+ and PRF groups had a greater increase in knee flexion, hip flexion, and greater decrease with regards to vertical ground reaction forces compared to the control group, but no differences were found between the two groups. Neither the RTF+ or PRF groups demonstrated a significant change in the knee extensor moment, hip extensor moment, or knee abduction angle post-intervention.


This study had several significant limitations that may have impaired the impact of the interventions provided. First of all, there was no “pre-screening” for excessive valgus and due to this fact, the included subjects had very low knee abduction angles at baseline. This limited the ability to make any kind of meaningful impact post-intervention. This is where utilizing a simple lower extremity functional test would have aided in providing a better patient population. Additionally, this study only measured immediate impact of the interventions without looking into long-term retention of the movement pattern, which would be more important in injury risk reduction. With a fairly small, albeit adequately powered, sample-size, the statistical significance of some of the changes may have been hampered.

Clinical Implications

Anterior cuciate ligament injuries have significantly increased from 40.9 to 47.8 per 10,000 patients according to a study looking into trends and demographics of ACL injuries in the United States4. This rising incidence coupled with very high re-injury rates to the contralateral and ipsilateral limb3,5,6 make developing injury risk reduction programs paramount. Due to its importance, several researchers have investigated faulty movement patterns and the incidence of ACL injury. These studies have identified prospective evidence linking decreased knee flexion and increased knee abduction angles as predictive of future injury2. While the aforementioned study did not produce a change to the knee abduction angle (likely due to a ceiling effect), there was a significant change in knee flexion angle, which may aide in decreasing the likelihood of future injury. While this is promising preliminary evidence, in order to have a significant impact, an injury prevention program must be repetitive and participants must have good compliance7,8 to create a long-term change in movement pattern. This study, due to its design, does not capture this aspect.


1. Ericksen HM, Thomas AC, Gribble PA, Doebel SC, Pietrosimone BG. Immediate Effects of Real-Time Feedback on Jump-Landing Kinematics. Journal of Orthopaedic & Sports Physical Therapy. 2015; 45(2): 112–118. doi:10.2519/jospt.2015.4997.

2. Hewett TE, et al. Biomechanical Measures of Neuromuscular Control and Valgus Loading of the Knee Predict Anterior Cruciate Ligament Injury Risk in Female Athletes: A Prospective Study. American Journal of Sports Medicine. 2005;33(4):492–501. doi:10.1177/0363546504269591.

3. Kamath GV. Anterior Cruciate Ligament Injury, Return to Play, and Reinjury in the Elite Collegiate Athlete: Analysis of an NCAA Division I Cohort. Am J Sports Med. 2014;42(7):1638–1643. doi:10.1177/0363546514530866.

4. Leathers MP, Merz A, Wong J, Scott T, Wang JC, Hame SL. Trends and Demographics in Anterior Cruciate Ligament Reconstruction in the United States. Journal of Knee Surgery. 2015. [Epub ahead of print]

5. Paterno MV, Rauh MJ, Schmitt LC, Ford KR, Hewett TE. Incidence of Second ACL Injuries 2 Years After Primary ACL Reconstruction and Return to Sport. Am J Sports Med. 2014;42(7):1567–1573. doi:10.1177/0363546514530088.

6. Rugg CM, Wang D, Sulzicki P, Hame SL. Effects of prior knee surgery on subsequent injury, imaging, and surgery in NCAA collegiate athletes. Am J Sports Med. 2014;42(4):959–964. doi:10.1177/0363546513519951.

7. Sugimoto D, Myer GD, Bush HM, Hewett TE. Effects of Compliance on Trunk and Hip Integrative Neuromuscular Training on Hip Abductor Strength in Female Athletes. Journal of Strength and Conditioning Research. 2014;28(5):1187–1194. doi:10.1097/JSC.0000000000000228.

8. Sugimoto D, Myer GD, Bush HM, Klugman MF, McKeon JMM, Hewett TE. Compliance With Neuromuscular Training and Anterior Cruciate Ligament Injury Risk Reduction in Female Athletes: A Meta-Analysis. Journal of Athletic Training. 2012;47(6):714–723. doi:10.4085/1062-6050-47.6.10.

What Are We Missing? The Influence of Fatigue.

The following is another article written for the online, video-based physical therapy continuing education company MedBridge

Recently, a lot of attention has been paid to re-injury and return to sport following anterior cruciate ligament reconstruction (ACLR) and the results continue to be less than exceptional. A recent case series of elite collegiate athletes who suffered ACL injuries prior to and during their college careers continually found difficulty returning to sports participation (Kamath et al., 2014). Of the 35 athletes who had undergone ACLR prior to enrollment in college, the rate of re-operation on the involved limb was 51.4%, the rate of re-rupture of the ACL graft was 17.4%, and contralateral ACL rupture was 20.0% within this population of athletes. Similarly, those who underwent ACLR during college had a 20.4% re-operation rate, 1.9% suffered re-rupture of the ACL graft, and 11.1% of these athletes underwent ACLR on the contralateral limb. In agreement with these findings, a prospective cohort study of 456 collegiate athletes conducted by Rugg and colleagues found that athletes entering college with a history of ACLR had a 892.9-fold increase in knee surgery compared to those who entered college without undergoing surgery. Unfortunately, these findings are not isolated to collegiate athletes as professional (Busfield et al., 2009) and high school athletes (McCullough et al., 2012) alike have similar statistics. Considering these numbers, it points to inadequate or premature return to athletic participation, which may be because we are overlooking a very important aspect of athletic competition.

First, let’s look at what factors have been shown to predispose these athletes to injury. Hewett et al conducted a prospective cohort study that identified factors that may put athletes at risk for initial ACL injury. After screening 205 female collegiate athletes with a drop-jump task, 9 athletes went on to suffer an ACL injury during the following season. These 9 athletes had several important factors in common in comparison to those who did not go on to suffer injury. Knee abduction angle at landing was 8° greater, knee abduction moment was 2.5 times greater, and there was a 20% higher ground reaction force in ACL–injured than in uninjured athletes. More importantly, the authors determined that injury could be predicted in those with an increased knee abduction moment (dynamic valgus) with 73% specificity and 78% sensitivity.

Prior to return to sport, many athletes will undergo functional testing (hop testing, Y-Balance Test, etc.), but do these tests, done under optimal circumstances, tell the full story or are we missing something?

Fatigue has been shown repeatedly to have negative affects on lower extremity biomechanics. A systematic review recently examined the literature pertaining to lower extremity biomechanics and neuromuscular fatigue during single-leg landings (Santamaria et al., 2010). After analyzing 8 studies and 141 total subjects, kinematic data revealed greater knee and hip flexion and increased dorsiflexion post-fatigue. More importantly, following the introduction of fatigue, there was no change in peak knee valgus angles. However, as anticipated/practiced drop-landings are performed primarily in the sagittal plane, these specific procedures may not be sufficient to determine movement patterns during athletic competition. When an unanticipated landing was used, the results were drastically different with a significant increase in peak knee valgus angle post-fatigue compared to pre-fatigue. This unanticipated landing would seem to represent the demands of athletic competition more accurately and thus demonstrates an increased risk of injury with neuromuscular fatigue. In agreement with these findings, Brazen et al found no change in frontal plane biomechanics during an anticipated drop-landing task after neuromuscular fatigue, however they did find a higher anterior-posterior time to stabilization (TTS) and vertical TTS, which once more increases the likelihood of injury.

More specific to patients following ACLR, Webster et al conducted a study comparing the response to neuromuscular fatigue between uninjured control subjects and athletes following ACLR. This study once again utilized an anticipated drop-landing task with data collected pre and post fatigue. Fatigue led to reduced flexion in the lower limb, increased hip and knee abduction, increased knee rotation, and reduced knee joint moments. The response to fatigue was similar with no significant differences between the ACL-reconstructed limb and the control group as well as the reconstructed limb and the contralateral limb. To further investigate the lower extremity biomechanics of athletes following ACLR, the Lower Extremity Error Scoring System (LESS) was developed. Padua et al determined the LESS to be a valid and reliable tool in assessing jump-landing biomechanics with good inter-rater reliability (ICC= 0.84) and excellent intra-rater reliability (ICC= 0.91). This evaluation tool involves counting the number of faulty movement patterns during a jump-landing task with < 4 errors being an excellent score, ≤ 5 being good, ≤ 6 being moderate, and > 6 being poor landing mechanics. When evaluating the influence of fatigue on LESS scores, Gokeler et al found significant differences between patients status-post ACLR and uninjured control subjects. The initial median score pre-fatigue for ACLR patients was 6.5 (poor) and 7.0 following fatigue, whereas the uninjured control subjects scored 2.5 (excellent) pre-fatigue and drastically increased to 6.0 (poor) post-fatigue. This shows an obvious decline in movement quality following fatigue, which may place both post-ACLR patients and uninjured controls at risk for injury.

Fatigue is an often-neglected aspect in the decision to return an athlete to sport or to assess an athlete’s initial risk for injury. This data should be used to further evolve our testing procedures to account for these potentially injurious movement patterns secondary to neuromuscular fatigue. Trent Nessler, DPT developed a fatigue protocol and concomitant testing procedure for return to sport and injury risk assessment purposes as part his Dynamic Movement Assessment. Albert Einstein was quoted saying, “The definition of insanity is to continually do the same thing over and over expecting a different result”. If we are to improve these return to sport and re-injury numbers, fatigue cannot be overlooked anymore and must be included in our clinical decision making process.

NMES, The Missing Link.

The following is another article written for the online, video-based physical therapy continuing education company MedBridge Education

Following any type of surgery, significant weakness of the primary and secondary musculature is common. For example, quadriceps weakness has been documented during the immediate post-operative phase following surgery (Snyder-Mackler et al), as well as years following rehabilitation (Rosenberg et al). Additionally, patients who undergo Total Knee Arthroplasty (TKA) exhibit similar findings. According to Mizner et al and Stevens et al, quadriceps strength drops 50-60% of pre-operative levels one month following TKA, despite the initiation of rehabilitation within 48 hours of surgery. Following this trend, Rokito et al found external rotation deficits following rotator cuff repair of 79% and 90% at six months and one year, respectively. Considering the severity and chronicity of these strength deficits, more effective interventions are warranted to restore strength and improve long-term outcomes. One particular modality that has been shown to improve these deficits is neuromuscular electrical stimulation (NMES).

Kim et al recently published a systematic review investigating the utility of NMES following ACL reconstruction to improve quadriceps function and strength. In this review, which involved 8 randomized controlled trials (RCTs), it was demonstrated that NMES in conjunction with exercise, compared to exercise alone or in combination with electromyographic bio-feedback, results in greater quadriceps strength recovery. As discussed in a previous article, return to sport is the ultimate goal for most patients and quadriceps femoris strength is of the utmost importance. Schmitt et al conducted a cross-sectional study to determine the impact of quadriceps weakness on return to sport functional testing. Those patients who presented with a quadriceps index (quadriceps strength involved/uninvolved) of < 85% performed inferiorly when compared to those with a quadriceps index of > 90%. Additionally, quadriceps weakness predicted performance on single-leg hop testing regardless of graft type, presence of meniscus injury, knee pain, and knee symptoms. Similarly, Fitzgerald et al not only measured increased quadriceps strength, but also length of time until progression to agility/plyometric training.  This randomized controlled trial found that those in the NMES group met the criteria for progression in a greater proportion than those in the control group. At 16 weeks, 85.7% (18/21) of patients receiving NMES achieved progression to agility training, whereas only 68% (15/22) of those in the control group achieved similar results.

In addition to ACL rehabilitation, those undergoing total knee arthroplasty enjoyed similar benefits. Stevens-Lapsley et al conducted a prospective, longitudinal, randomized controlled trial investigating the effects of NMES on patients following TKA. Patients were randomized into a group receiving standardized rehabilitation or to a group receiving the same rehabilitation in addition to NMES, which was initiated 48 hours following surgery. In both the short-term (3.5 weeks) and long-term (52 weeks), patients in the NMES group demonstrated superior quadriceps strength, hamstring strength, and functional performance (Timed “Up & Go” Test, the Stair-Climbing Test, and the Six-Minute Walk Test). Additionally, Walls et al investigated the pre-operative utility of this modality. Those individuals who received NMES achieved significant increases in quadriceps strength from weeks 6-12, whereas the control group did not achieve the same feat. Lastly, in a case report published by Petterson et al, a cyclist presenting 12 months following bilateral TKA displayed significant impairments with regards to quadriceps strength and volitional muscular contraction. Following six weeks of NMES and volitional therapeutic exercise, this patient achieved a 25% improvement in left quadriceps femoris maximal volitional force output and his central activation ratio (CAR) also improved from 0.83 to 0.97 as quantified by the burst superimposition technique. Furthermore, strength gains continued after the end of treatment as his quadriceps strength index was 94% of his right leg at 12 months following treatment.

While the majority of research pertaining to the efficacy of NMES has been done in the lower extremity, this is not the only region where its benefits can be found. As previously stated, muscular deficits frequently accompany patients following rotator cuff repair. To this end, Reinold et al investigated the ability of NMES to affect maximum voluntary contraction of the infraspinatus muscle. In comparison to trials without NMES, peak force production was significantly greater with an average force of 3.75 kg in comparison to just 3.08 kg. This increase was present regardless of patient age, size of the tear, intensity of the current, or the number of days following surgery. While this preliminary study does not give credence to the effect during a full course of rehabilitation, it does speak to the ability of NMES to increase the ability of this musculature to contract safely and more efficiently following surgery. Further research will define the effectiveness of this intervention following rotator cuff pathology, however this study lends hopeful possibilities.

Neuromuscular electrical stimulation should play an integral role in your practice regardless of setting. Patients presenting with strength deficits and impairments will benefit from NMES when combined with volitional exercise. Meryl Gersh, PT, PhD goes into great detail with regards to electrode placement, optimal dosage, and indication criteria in her course “Applying Electrical Stimulation in Your Physical Therapy Practice”. Increasing your patients’ volitional muscular contraction is of the utmost importance when it comes to fostering improved long term outcomes and NMES in conjunction with their current program should yield enhanced results.

Research Review: Effect of Prehabilitation on the Outcome of Anterior Cruciate Ligament Reconstruction


In my first in a series of ‘Research Review’ articles for MedBridge Education, I will review a recent study that appeared in The American Journal of Sports Medicine. Shaarani et al investigated the utility of a Prehabilitation program for patients scheduled to undergo anterior cruciate ligament reconstruction (ACLR). Considering the variable rate of return to sport following ACLR (43-93%), urgency exists for improving rehabilitation following ACL injury.

Study Design

Randomized Controlled Trial (RCT).


20 patients with a rupture of the ACL were recruited from 2 orthopedic centers between December 2010 and December 2011. Following randomization, 11 patients were assigned to the intervention group while 9 were placed in the control group. No significant differences existed between groups for age, height, weight, body mass index, and Tegner activity level before/after injury.

Inclusion Criteria: Males between the ages of 18 and 45 years old with an isolated ACL tear. All patients had a positive anterior drawer, Lachman, and pivot-shift test.

Exclusion Criteria: Associated fractures, meniscal repair, collateral ligament injury requiring repair/reconstruction, comorbidities that would be contraindicated from high physical exertion, and living outside the Greater Dublin area for practical reasons related to exercise supervision and exercise gym usage.


Outcome Measures: Single-leg hop test, peak torque of the quadriceps and hamstring, muscle cross-sectional area (CSA), Modified Cincinnati Knee Rating System (mCKRS), and Tegner activity level.

Randomization: From a pool of 437 patients, 56 were eligible following inclusion/exclusion criteria. There were, however, 14 non-responders and 19 subjects who refused to participate. Randomization was determined following outpatient consultation. Opaque envelopes were used to randomly assign individuals to their group.

Interventions: The Prehabilitation Group (PG) was enrolled in a 6-week exercise program, which consisted of supervised resistance and balance training. This program was comprised of 4 exercise sessions per week, which included 2 supervised gym sessions and 2 supervised home sessions. The primary focus was lower limb strengthening with a quadriceps emphasis, as well as proprioceptive training. Each exercise consisted of 3 sets of 12 repetitions and the weights were increased weekly by 10-15%. During the last gym session, the weights were reduced to the previous week’s value to prevent preoperative fatigue and to favor the muscular response to endurance and gaining mass. In contrast, the Control Group (CG) was not given a pre-operative exercise program; however these patients were not discouraged from exercise or taking part in normal activity of daily living before surgery. Postoperatively, both groups received standardized physical therapy sessions, which included increasing range of motion (ROM) and weight-bearing while improving symmetry and gait pattern.


Immediately following the 6-week Prehabilitation program, the intervention group showed several significant improvements prior to surgery. These benefits included the following: significantly improved single-leg hop testing; increased quadriceps and vastus medialis CSA, and improved mCKRS. At 12 weeks post-operative, the rate of decline in the single leg hop test was less and the mCKRS was significantly improved in the exercise group compared with the CG, however no changes existed between groups in CSA. Of particular importance was that on average patients in the PG returned to sport in 34.2 weeks versus 42.5 weeks in the CG though this did not reach statistical significance (P=0.055).


The most important limitations of this study were the small sample size (n = 20) and lack of a long-term follow-up in comparison to the typical rehabilitation length. It is therefore difficult to extrapolate these short-term benefits to long-term outcomes. Additionally, single-leg hop and peak quadriceps torque testing were observed by an individual who was not blinded to the treatment groups. Finally, in terms of the study design itself, utilizing a sham exercise program would have eliminated the potential attention bias.

Clinical Implications

This pilot study supports implementing a prehabilitation program following ACL injury in preparation for surgical intervention. As previously stated, the percentage of patients who are able to return to sport following ACLR is broad and relatively unimpressive. The benefits of prehabilitation demonstrated during this initial investigation could have a profound impact on return to sport following ACLR. The improvement in single-leg hop testing is particularly encouraging, as it has been documented to be a problematic area with regards to athletes following ACLR. Both Myers et al and Xergia et al found significant asymmetries in single-leg hop testing between individuals who had undergone ACLR and uninjured control subjects. Following rehabilitation, athletes need to have the proprioceptive ability and confidence to perform single-leg stopping, cutting, and jumping activities without hesitation. Coinciding with these measures, this study did show a shorter timeframe for return to sport in athletes who completed a course of prehabilitation. Despite not reaching statistical significance, an average decrease of over 8 weeks is clinically meaningful to any sports medicine practitioner, athlete, or coach.

Shaarani SR, O’Hare C, Quinn A, Moyna N, Moran R, O’Byrne JM. Effect of Prehabilitation on the Outcome of Anterior Cruciate Ligament Reconstruction. American Journal of Sports Medicine. 2013; 41(9): 2117–2127.

The Psychology of Return to Sport

Biomechanical and neuromuscular factors receive considerable attention in discussing Return to Sport Following ACL Reconstruction. Psychological considerations, however, despite playing an integral role in returning an injured athlete to their respective sport, often go under-appreciated. The purpose of this piece is therefore to briefly review the literature related to the psychology of ACL injury and surgery, and to discuss how the rehabilitation professional can enhance their understanding of the psychological domain to foster improved outcomes in working with this population of athletes.

Once a patient has successfully met all return to sport criteria, the next step naturally involves returning to sport. While some patients seamlessly return to their pre-injury status, others struggle with simply returning to their sport. One needs to look no further than the case of Derrek Rose, star of the Chicago Bulls and MVP of the NBA in 2011, to appreciate the challenge in returning an athlete to sport. After sustaining an ACL tear and subsequently undergoing surgery, he was sidelined for approximately 16 months. In contrast to this situation, Adrian Peterson, defied all odds by returning to the starting lineup nine months following his surgery. While both of these athletes undoubtedly worked hard throughout the rehabilitation process, other factors may account for the difference in time in returning to their respective sports.

According to a recent systematic review conducted by Te Wierike et al.,fear of re-injury was the leading cause of failure for athletes with an ACL injury and subsequent reconstruction to return to sport. Along these same lines, Ardern et al conducted a systematic review with meta-analysis of return to sport outcomes of nearly 5,000 patients following ACL reconstruction. This study demonstrated that only 63% of patients returned to their pre-injury level of competition. Again, fear of re-injury was the most common reason cited for a reduction in or cessation of sports participation. In agreement with the aforementioned studies, a case-control investigation conducted by Ardern et al, found that significant independent contributions for returning to pre-injury level one year post-operatively were explained by psychological factors. These included subjective readiness to return to sport, fear of re-injury, and sport locus of control. This study also determined that factors influencing athletes’ prospective judgment of their ability to return to sport predicted returning to their pre-injury level.

A cross-sectional study performed by Chmielewski et al found that fear of movement/re-injury levels appear to decrease during ACL reconstruction rehabilitation and are associated with function in the timeframe when patients return to sports. Therefore, being psychologically prepared for return to sport is critical when considering each patient’s readiness. In addition to this study, Ardern et al conducted a systematic review looking into the psychological factors involved in returning athletes to sport following injury. This review of 11 studies and nearly 1,000 patients determined that the three central elements of return to sport were from the self-determination theory, which includes: autonomy (urge to be causal agents of one’s own life and act in harmony with one’s integrated self); competence (seek to control the outcome and experience mastery); and relatedness (universal want to interact). This same study found that positive psychological responses including motivation, confidence, and low fear were associated with an increased likelihood of returning to one’s pre-injury level status in a more timely manner.  Naturally, return to sport elicits a certain level of fear and anxiety for all athletes, though individuals who possess these internal motivating factors enjoy improved post-operative outcomes.

Considering this information, the question becomes how can clinicians identify those patients who may be at a psychological disadvantage during the rehabilitation process? According to Chmielewski et al, a patient’s psychosocial profile can be positively altered in the short-term following ACL reconstruction. This means that clinicians must take the time to accurately identify those individuals who may be at risk of poor outcomes due to fear of re-injury or fear avoidance beliefs. This can be accomplished through the use of the Tampa Scale for Kinesiophobia (TSK-11), the Fear Avoidance Beliefs Questionnaire (FABQ), and/or the more specific Injury-Psychological Readiness to Return to Sport (I-PRRS) Scale. Recently, Lentz et al determined that individuals with a lower TSK-11 score were more likely to return to their pre-injury level of competition following ACL reconstruction. While the other two outcome measures have greater scientific backing at this point, the newer I-PRRS has just begun the process of validation. In 2009, Glazer et al published a validation study to support the scale’s utility. The I-PRRS scores were found to be lowest after injury, increased before release to practice, increased again before returning to competition, and had no change after competition. This demonstrates the general progression of psychological preparedness and thus the validity needed to make this a useful measure for clinicians when determining an athlete’s readiness for return to sport.

These outcome measures may give us the ability to more accurately identify those individuals at risk for suboptimal outcomes. Regardless of baseline mentality, however, recovery from injury demands a psychologically driven process. This Biopsychosocial Model is composed of 4 distinct processes (Wiese-Bjornstal et al). The first of which is Cognition, which includes the thoughts an athlete experiences following injury. Within this category lies the athlete’s internal Health Locus of Control (HLOC), which is the capacity that the athlete believes they control the events in their life. Nyland et al found that athletes with a high internal HLOC were more satisfied with their knee function in addition to their ability to perform ADLs, and participate in sport following ACL reconstruction. The second category is the patient’s Affect.  BioPsySoc-InjThis concerns the way an athlete feels following injury. As most clinicians appreciate, injuries can lead to substantial psychological changes, sometimes verging on depression. Studies have shown, however, that there are positive psychological changes as rehabilitation progresses, with fewer negative emotions and more positive feelings about returning to sport. In light of this information, the fear of re-injury has significant impact on the rehabilitation process and can lead to sub-optimal outcomes, potentially preventing return to athletics. The Behavior of the patient throughout the rehabilitation process can also be an influential factor. The two most important behaviors for patients following ACL reconstruction are avoidance coping and rehabilitation adherence. Avoidance coping can be broken into behavioral avoidance coping (the conscience decision to remove oneself from a threatening environment) and cognitive avoidance coping (the responses aimed at denying or minimizing the seriousness of a crisis). While these avoidance techniques may be beneficial in the recovery process, poor adherence to physical therapy has been shown to be detrimental to recovery. Brewer et al found that patients who had a higher score for adherence experienced fewer knee symptoms compared to those who demonstrated poor adherence to their physical therapy program. The final cornerstone to the Biopsychosocial Model is the Outcome. A deficiency or inadequacy in any combination of the three previous categories can negatively impact a patient’s post-rehabilitation outcome. As was shown by Lentz et al, return to pre-injury level of sports participation is multi-factorial and those who did return had less knee joint effusion, fewer episodes of knee instability, lower knee pain intensity, higher quadriceps peak torque-body weight ratio, higher IKDC scores, and lower TSK-11 scores.

Finally, considering this model and the personality traits associated with successful outcomes, what can clinicians do to foster improved outcomes following ACL injury and/or surgery? Regardless of whether or not reconstruction is performed following ACL injury, several psychological interventions have been proven beneficial for athletes during their rehabilitation (relaxation, imagery, training of self-efficacy, and modeling). Cupal and Brewer conducted a randomized controlled trial comparing the outcomes of patients who received relaxation and guided imagery training in conjunction with a typical post-operative protocol to those who only completed the protocol. In the end, the experimental group had greater knee strength, less re-injury anxiety, and less pain compared with the placebo and control group. In order to improve patients’ self-efficacy through modeling, Maddison et al gave their intervention group two separate videos to aid the ability of their athletes’ to cope throughout the rehab process. This study showed that patients, who watched the videos, perceived less pain and had more self-efficacy than those who did not receive this intervention. It should also be noted that athletes often benefit from discussing their injury (i.e. how it happened and how it has affected their life). Additionally, Mankad et al found that athletes who wrote about their injury in the form of written disclosure statements had a reduction of stress and total mood disturbances.

Returning an athlete to sport requires the use of a specific criterion-based protocol, functional sport-specific testing, and proper psychological management of stressors and emotions associated with the injury.  Successful rehabilitation of an athlete back to their sport involves careful consideration of all of these aspects. Considerable attention has been paid to the pathoanatomical, biomechanical, and neuromuscular aspects though sports medicine professionals often neglect the psychological impact. As the recognition and implementation of psychologically-driven interventions increases, positive outcomes with regards to return to sport should follow.

What is the Key to the ACL Epidemic? Prevention.

In my previous post, I discussed the current research and concepts with regards to Return to Sport following Anterior Cruciate Ligament Reconstruction (ACLR)… Now it is time to discuss how we, as clinicians, can help to prevent these injuries altogether.

A recent Systematic Review and Meta-analysis of 14 studies and 27,000 participants conducted by Gagnier et al found that neuromuscular and educational interventions appear to reduce the incidence rate of ACL injuries by approximately 50%. Within this systematic review, 109 ACL injuries were prevented; that means 109 athletes will not have to face the unfortunately low return to sport and high re-injury rate associated with ACLR. The first ACL prevention program was published in 1999 by Hewett et al and focused on flexibility, plyometrics, weight training, and emphasized maintaining adequate frontal, transverse, and sagittal plane mechanics throughout each exercise/movement. During this study of 1,263 athletes, there were five non-contact ACL injuries in the untrained female group, one in the untrained male group, and none in the trained female group. This study determined that female athletes who do not undergo neuromuscular training have a 3.6x increased likelihood of sustaining a non-contact ACL injury. Since this initial study, several additional randomized controlled trials have also shown the benefits of injury prevention programs on the incidence of ACL injury (Mandelbaum et al, Gilchrist et al, Olsen et al, Caraffa et al, Myklebust et al, and Petersen et al).

In addition to these randomized controlled trials, there have also been several systematic reviews detailing the benefit of neuromuscular training in the prevention of serious knee injury. The first of which was a meta-analysis conducted in 2006 by Hewett et al of 6 studies investigating prevention programs for female athletes. This analysis found that 4 out of 6 neuromuscular intervention programs significantly reduced knee injury incidence, and 3 out of 6 significantly reduced anterior cruciate ligament injury incidence. Overall, the meta-analysis of these 6 studies demonstrates a significant effect of neuromuscular training programs on anterior cruciate ligament injury incidence in female athletes. Later in 2010, Yoo et al found that the odds ratio of injury prevention was 0.40 with the implementation of a prevention program. Yoo and colleagues also determined through meta-analysis that pre- and in-season neuromuscular training with an emphasis on plyometrics and strengthening exercises was effective at preventing ACL injury in female athletes, especially in those under 18 years of age. Finally, in 2012, Sadoghi et al found an overall risk reduction following the implementation of a prevention program of 52% for female athletes and 85% for male athletes. This coupled with the overall reduction of 50% stated by Gagnier et al shows more than enough reason to suggest the need for widespread usage of injury prevention programs amongst all athletes.

With all of this readily available evidence, surely these programs are being utilized by coaches at all levels, right? Unfortunately, according to a survey of female soccer coaches conducted by Joy et al, only 19.8% of coaches implement an Injury Prevention Program (IPP). Of these coaches who chose to implement an IPP, they did so for injury prevention (93%) as well as performance enhancement (36%). Performance enhancement is what will drive athletes, coaches, and parents toward IPPs – with the added benefit of a decreased likelihood of a catastrophic season-ending injury. Thankfully, the literature is in favor of IPPs with regards to performance enhancement as well. In 2005, Myer et al conducted a study investigating the performance enhancing effects of their injury prevention program. They found significant improvements in 1-Repitition Maximum Bench Press and Squat, Single-Leg Hop Distance, Vertical Jump, and speed in the 9.1 meter dash. This study also showed an overall decreased knee valgus and varus torque during functional movement as an added benefit. While injury prevention is the end goal, performance enhancement is what will bring clients through your doors and will make coaches change their philosophy. It is up to physical therapists, athletic trainers, strength & conditioning coaches, and physicians to bring this information to coaches and players alike. We have the evidence to support the effectiveness of these programs, but we need to take the time to educate those who will benefit most.

All this being said, what makes a successful program? While specific areas of training have not been adequately differentiated in terms of effectiveness, there is a general consensus as to what aspects should be included. These areas include a dynamic warm-up, restoration of proximal stability, proprioceptive training, plyometric training, neuromuscular re-education, strength training, and education. One area cannot be proven more effective than another, however certain qualities of a program have been deemed indicative of an effective program. The first and likely most important quality is patient/client compliance. Wingfield et al recently conducted a cluster randomized controlled trial to evaluate the effectiveness of a neuromuscular warm-up program in preventing acute knee injury in adolescent female soccer players. Not surprisingly, they found that athletes who performed ≥ 1 exercise session per week had a lower rate of ACL injury, severe knee injury, and of any acute knee injury compared to the control group. Additionally, in a systematic review conducted by Sugimoto et al, it was found that incidence rates of ACL injury were lower in studies with high rates of compliance with neuromuscular training than in studies with low compliance rates. So, this begs the question of, “How do we make our athletes compliant?” In my opinion, we must provide a solid, systematic evaluative and progressive program addressing each individual athlete’s deficiencies.

There are several Injury Prevention Programs available from the simple (FIFA 11+, Santa Monica Prevent Injury and Enhance Performance Program, ect.) to the more advanced systematic programs implemented by trained fitness and healthcare professionals. Of the programs available, there are two that appear to encompass all aspects of injury prevention that therapists and/or strength & conditioning coaches should consider implementing. The first of which is the Dynamic Movement Assessment (DMA) developed by Trent Nessler, DPT. The DMA consists of a thorough functional assessment backed-up by the use of video feedback to provide visual input to both athletes and clinicians alike. This allows for detailed understanding of where these faulty movement patterns are stemming from and how these deficits should be corrected. The second program is seemingly simpler, albeit a much more researched program in the Functional Movement Screen (FMS)/Selective Functional Movement Assessment (SFMA). These systems are comprised of several tests that provide the ability to ‘screen’ athletes for the poor movement patterns often associated with increased likelihood of injury. Regardless of the specific system, the key to any successful program is selecting a solid classification system to identify those at risk and implement exercise programs to improve their specific movement patterns and/or deficient muscular performance.

ACL Reconstruction: When Can I Play Again?

“When can I play ___________ again?”

Such a simple question. Following an anterior cruciate ligament reconstruction (ACLR), this is the answer that everyone (clinician, patient, coach, and parent) wants to know. Unfortunately, this simple question does not have a simple answer.

With copious amounts of research devoted to this pathology, it would seem like an easy question to answer, but that is far from the reality. In a study of 100 soccer athletes, only 72% returned to sport following ACLR and at 7 year follow-up, only 36% were still playing (Brophy et al). This low return to sport percentage is not isolated to soccer players, as a similar study (McCullough et al) found that only 63% of high school and 67% of college-level american football players were able to return to sport. Even more concerning, there is a substantial number of patients that will have a revision or additional surgery. According to Hettrich et al, at a 6 year follow-up for 980 patients, 18.9% had additional surgical procedures performed on the same knee that initially underwent ACLR. That same study showed that 7.7% had a revision ACLR, while 6.4% had an ACLR on the opposite knee. A study published by Paterno et al, identified a significant injury rate in subjects who had previously suffered an ACL tear. This is especially evident in young females who have greater than a 25% incidence of ACL rupture in their first year back to competition. Why is this the current state of affairs with this injury, and what can we do to improve these outcomes?

Before determining when a patient is ready to return to their sports, it is first necessary to understand which biomechanical factors and faulty movement patterns may have contributed to their initial injury. In 2005, Hewett et al published a landmark study identifying biomechanical factors that can help predict initial rupture of the ACL. dynamic valgus In this study, 205 female athletes performed a jump-landing task, and 9 of these went on to rupture their ACL during the following season. During the jump-landing task, these nine female athletes demonstrated increased knee abduction at landing (8°), which translated to 2.5 times more than all the others who did not sustain an injury. Those who injured their ACL also produced 20% higher ground reaction force upon landing, which was potentially influenced by a decreased knee flexion angle upon landing. All these factors considered, individuals who are at risk for rupturing or re-rupturing their ACL demonstrate landing patterns that coincide with the typical dynamic valgus mechanism of injury. This work led to the refinement of recommended ACL rehabilitation protocols (Hewett et al). This thorough criterion-based protocol placed a major emphasis on the need for “ACL Prevention Programs” to serve as a model for the last phase of ACL reconstruction rehabilitation.

All this being said, how can we assess these risk factors in our patients? In general, there are two classes of functional testing that should be utilized prior to clearing someone to return to sport; proprioceptive/dynamic postural control and functional hop testing. Both of which play an integral role in assessing a patient’s ability to control dynamic valgus. This valgus is often associated with the development of lower extremity pathology (patellofemoral pain syndrome, iliotibial band syndrome, ACLR, ect.). These tests challenge patients to a threshold that can identify motor control, proprioception, and muscular strength/endurance deficits. These are factors that cannot be assessed accurately with the typical range of motion, manual muscle test, and Lachman testing that seems to be common practice with regards to return to play criteria.

There are many proprioceptive tests that can be utilized in the clinical setting, however there are two that should be included in any ACLR rehabilitation program. The first, and probably most well-known, is the star excursion balance test (SEBT). This test originally involved the subject balancing on one leg while reaching with the opposite limb in 8 different directions. The test has since been modified and aptly renamed the Y-Balance Test (YBT), as the only directions included are anterior, posterolateral, and posteromedial. These two variations of the test were examined in a systematic review by Gribble et al and were both found to have excellent reliability (YBT: intra-rater reliability = 0.85-0.89 and inter-rater-reliability = 0.97-1.00, SEBT: 0.78-0.96 and 0.81-0.93). In addition to being a reliable test, it is also very applicable to ACLR patients. Delahunt et al evaluated the difference between limbs of female athletes who have undergone ACLR with regards to the performance of the SEBT. These subjects were, on average, 2.9 years removed from surgery and still demonstrated significant asymmetry. Significant deficits were seen in both the posterolateral and posteromedial directions, while altered hip frontal, sagittal, and transverse plane kinematics were also evident during testing. To reinforce the significance of this asymmetry in performance and kinematic profile, Plisky et al found that basketball players with anterior right-to-left reach differences of more than 4 cm were 2.5 times more likely to sustain lower extremity injuries. More importantly they also found that girls with a composite reach score of less than 94% of their limb length were 6.5 times more likely to sustain a lower extremity injury. Regardless of whether you utilize the full SEBT or the shortened YBT, quantifying the potential faulty movement patterns that likely predisposed this individual to their initial injury is paramount to a successful return to sport.

Y-Balance Test

In addition to the use of the SEBT or YBT, the use of the lateral step-down test (LSDT) is integral to assessing each individual patient’s movement quality and resulting strength, range of motion, and/or motor control deficits. While there is not as much literature to support this specific test, it still provides a snapshot into the athlete’s ability to control stability at the knee in both the frontal and transverse planes. As diminished strength of the hip abductors and external rotators frequently accompany pathology of the lower extremity, this test provides information to help individualize a patient’s program. While the efficacy of this test’s ability to predict future injury has not been assessed, its reliability has. In a study conducted by Piva et al, the reliability of the LSDT was moderate (ICC= 0.67, Percent Agreement= 80%). Additionally, a more recent study by Boden et al determined that the interrater reliability of the LSDT was equal to 0.59 (fair agreement) and the percent agreement was 83%. While this test is not as well known as the previously mentioned proprioceptive tests, it still provides a simple, reliable way to qualitatively assess your patient’s postural control early in the rehabilitation process.

As your patient continues to progress through their rehabilitation, more functionally appropriate and demanding tests and measures should be implemented. Of particular interest, regardless of your patient’s sport, are four functional jump tests (single hop, X-hop, triple hop, and timed hop). Xergia et al found significant asymmetries in terms of performance on the functional hop test, lower extremity kinematics, and isokinetic strength testing when comparing individuals following ACLR to asymptomatic control subjects. The ACLR group demonstrated greater isokinetic knee extension deficits and greater performance asymmetry during all three functional hop tests in comparison to the control group at 6 and 9 months post-operatively. Hop Testing In agreement with these findings, Myers et al evaluated the percent asymmetry between the four different hop tests in subjects who had undergone ACLR and normal uninjured control subjects. Predictably, the ACLR group demonstrated statistically significant symmetry deficits in comparison to the control group. Average symmetries for the ACLR group only approached 92% for the single-leg hop, 91% for the triple-hop, 92% for the crossover hop, and 96% for the timed hop test, whereas the only test that did not reach 100% symmetry for the control group was the crossover hop test (97%). In addition to these studies, Schmitt et al found that individuals who demonstrated a greater level of quadriceps femoris strength also performed superiorly on hop testing and actually performed at the same level as uninjured control subjects. While these seem like excellent procedures to assess in the clinic, how do these functional tests translate to our patient’s ability to perform everyday functional activities? Di Stasi et al evaluated gait asymmetries between individuals who passed their return to sport criteria (isometric quadriceps strength test, 4 single-legged hop tests, and 2 self-report questionnaires) and those who failed at 6 months status-post ACLR. They found that athletes who demonstrate superior functional performance 6 months after ACL reconstruction may have fewer abnormal and asymmetrical gait behaviors than those who could not pass the testing battery.

The need to ensure our patient’s ability to return to play at a level that does not compromise their safety should be our primary goal as clinicians, but are we actually using this information? The short answer is no. Barber-Westin et al conducted a systematic review of the return to sport criteria within the current research literature. Of the 264 studies included, 105 (40%) provided no criteria of any kind to release patients, 84 (32%) only relied on time since surgery, and 40 (15%) relied on time since surgery and subjective criteria. All in all, only 35% of studies included objective measures in their rationale for releasing their patients to their sport. This past year, a survey and subsequent analysis was conducted by Peterson et al in order to determine the current practice patterns of orthopedic surgeons with regards to return to sport. Unfortunately, this study yielded similar results. Of the 221 experienced arthroscopic surgeons surveyed, only ~40% utilized some sort of proprioceptive test, muscular strength analysis, or even the single-leg hop test.

“Only 35% of studies provided objective criteria to determine release of patients back to sport!”

Rehabilitation following ACLR should not be based upon specific time frames, but instead upon the achievement of specific criteria. This should dictate progression to the next stage. Time does not heal all wounds. These wounds must be treated with an efficacious program structured towards the specific demands of his/her sport and the underlying deficits that resulted in the initial injury. Terry Malone’s course, “ACL and PCL Injuries, Surgeries, and Rehabilitation” and Phil Plisky’s course, “Return to Sport and Discharge Planning”, provide many excellent clinical pearls that clinicians should look to implement within their treatment plans and eventual discharge planning.

While we cannot control all of the factors that affect a patient’s rehabilitation (psychological profile, concomitant injuries, level of competition, ect.), we can provide them with a safe, reliable, and effective plan guided by the use of specific and relevant tests and measures. We need to embrace the need to appropriately assess how each patient moves and any deficits that need to be addressed prior to releasing them to their respective sport. We only provide a disservice if they are released to play at 6 months only to re-injure themselves at 9 months. It is our responsibility to release them only when they can appropriately handle the stresses of their sport, rather than on a specific time frame or when they have a 5/5 grade on a manual muscle test.

So, do you agree or disagree? I would love to hear some feedback as to what you need to see before releasing an athlete to their sport…