ASSOCIATION BETWEEN CHANGES IN PSYCHOLOGICAL READINESS AND SUBJECTIVE KNEE FUNCTION AFTER ACL RECONSTRUCTION

This study found a moderate positive correlation between the improvements in psychological readiness and subjective knee function in athletes recovering from ACL reconstruction between 3.5 and 7 months post-surgery, suggesting that these domains progress in parallel and should be monitored concurrently to optimize rehabilitation and return-to-sport outcomes.

The Gist

Imagine your knee is like a car that just had a major engine repair (ACL reconstruction). You know the mechanics are working, the parts are new, and the engine is running. But there's a catch: you are the driver.

This study is about the relationship between two very different things:

1. How the "car" feels: Is the engine smooth? Is the steering tight? (This is Subjective Knee Function).
2. How the "driver" feels: Do you trust the car enough to drive it on the highway? Are you scared it will break down again? (This is Psychological Readiness).

The Big Question

Doctors have always wondered: Do these two things improve at the same time?

Sometimes, a patient might feel their knee is perfect (the car is running great) but still be too scared to play sports (the driver is too nervous to drive). Other times, a patient might feel super confident and ready to race, even though their knee still feels a bit wobbly (the driver is overconfident, which is dangerous).

The researchers wanted to see if, as time goes on, the "car" getting better and the "driver" getting braver happen together, or if they are totally separate journeys.

What They Did

The team looked at 48 young athletes (mostly high schoolers and college students) who had just had knee surgery. They checked in on them twice:

• Time 1: About 3.5 months after surgery (early recovery).
• Time 2: About 7 months after surgery (late recovery).

At both times, they asked the athletes two questions:

1. "On a scale of 0 to 100, how does your knee feel?" (The IKDC score).
2. "On a scale of 0 to 100, how ready do you feel to get back to your sport?" (The ACL-RSI score).

They then calculated how much each score changed between the two visits.

The Discovery

The researchers found a moderate connection between the two.

Think of it like a dance. They aren't perfectly synchronized (like a robot moving in lockstep), but they are definitely dancing to the same song.

• When an athlete's knee started feeling stronger and less painful, their confidence usually went up, too.
• When their confidence grew, their perception of their knee function usually improved as well.

The "Parallel Progress" Finding:
The study concluded that between months 3.5 and 7, these two things tend to move in the same direction. If your knee feels better, you likely feel braver. If you feel braver, your knee likely feels better.

A Few Interesting Twists

• The "Driver" was slower to warm up: While everyone in the study saw their knee feel better (the car improved), about 25% of the athletes actually felt less ready to play or stayed the same. It seems the "driver" (the mind) sometimes takes longer to trust the "car" (the knee) than the knee takes to heal physically.
• Why the difference? The researchers suggest that just because your knee doesn't hurt doesn't mean you feel ready to jump, cut, and land like you used to. You might need to practice those specific scary moves before your brain gives you the "green light."

Why This Matters for You

If you are an athlete recovering from a knee injury, or a parent/coach watching one:

1. Don't ignore the mind: You can't just fix the physical knee and assume the mental part will fix itself. They are linked. If you are struggling mentally, your physical progress might stall, and vice versa.
2. Check both gauges: Don't just ask, "Does it hurt?" Ask, "Do you feel ready?" If your knee feels great but you're still terrified, you need mental training. If you feel ready but your knee is still weak, you need more physical work.
3. It's a team effort: The study suggests that the best way to get back to sports is to work on the physical strength and the mental confidence at the same time.

In short: Healing a knee isn't just about fixing the ligament; it's about convincing the brain that the repair is real. And luckily, this study shows that as the body heals, the mind usually catches up right along with it.

Technical Summary

1. Problem Statement

Following Anterior Cruciate Ligament Reconstruction (ACLR), two critical patient-reported outcomes (PROs) determine prognosis: psychological readiness to return to sport (RTS) and subjective knee function.

• The Gap: While existing literature establishes that these two domains are correlated when measured at a single point in time, it remains unclear how they progress in tandem over the course of rehabilitation.
• Clinical Risk: Mismatches between these domains pose significant risks. An athlete with high functional scores but low psychological readiness may face delayed RTS due to fear. Conversely, an athlete with high psychological readiness but poor functional scores may return prematurely, increasing reinjury risk.
• Objective: The study aims to determine if changes in psychological readiness (measured by the ACL-RSI) and subjective knee function (measured by the IKDC) are proportionally associated between early (3.5 months) and late (7 months) recovery phases.

2. Methodology

• Study Design: Secondary analysis of prospectively collected data from a clinical repository (REDCap).
• Participants:
  • Sample Size: $N = 48$ athletes (27 male, 21 female).
  • Demographics: Age 15–25 years (Mean: $17.7 \pm 1.8$ years).
  • Inclusion Criteria: Ipsilateral autograft ACLR, pre-injury MARX activity score > 8, and completion of both ACL-RSI and IKDC questionnaires at two specific time points.
  • Exclusion Criteria: Multi-ligament injuries, additional procedures (e.g., MCL/LCL/PCL repair), history of prior ACL injury, or surgery delayed >12 months post-injury.
• Data Collection Points:
  • Early Recovery: $3.5 \pm 1$ months post-ACLR.
  • Late Recovery: $7 \pm 1$ months post-ACLR.
• Instruments:
  • ACL-RSI (12 items): Assesses emotions, confidence in performance, and risk appraisal (0–100 scale).
  • IKDC (19 items): Evaluates symptoms, function, and sports limitations (0–100 scale).
• Statistical Analysis:
  • Calculated percent change for both ACL-RSI and IKDC scores between the two time points.
  • Used Spearman's rank correlation ($\rho$) to assess the association between the percent changes, chosen to account for non-linear relationships and non-normal distributions.
  • Employed non-parametric bootstrapping (10,000 resamples) to generate 95% Confidence Intervals (CI).
  • Significance level set at $p < 0.05$.
  • Note: The study was underpowered for the original hypothesis (which predicted a weak correlation requiring $N=194$), but the observed effect size allowed for detection of a moderate correlation.

3. Key Results

• Magnitude of Change:
  • Mean percent change in ACL-RSI: $40.7 \pm 57.1\%$.
  • Mean percent change in IKDC: $24.8 \pm 18.1\%$.
  • Observation: While all athletes showed improvement in IKDC (100% positive change), 25% of athletes showed no improvement or a decrease in ACL-RSI scores during this period.
• Correlation:
  • A statistically significant moderate positive correlation was found between the percent changes in ACL-RSI and IKDC.
  • Spearman's $\rho$: $0.350$ (95% CI [0.089, 0.584]).
  • p-value: $0.012$.
• Visual Data: Figure 1 (linear regression) confirms that as subjective knee function improves, psychological readiness tends to improve in parallel, though with individual variability.

4. Key Contributions

• Temporal Concordance: The study provides evidence that psychological readiness and subjective knee function do not just correlate at a single snapshot but progress concurrently during the 3.5 to 7-month post-operative window.
• Refutation of Independence: Contrary to a previous study by Ohji et al. (which found independent improvements from pre-op to 6 months), this study suggests that once rehabilitation is underway, improvements in physical function are linked to improvements in psychological state.
• Clinical Utility: The findings suggest that clinicians can use one metric as a proxy for the other to some extent. If an athlete's functional scores are stagnating, their psychological readiness is likely stagnating as well, and vice versa.
• Identification of Mismatches: The data highlights a specific subgroup (25% of the cohort) where functional gains occurred without psychological gains, identifying a potential "mental barrier" group that requires targeted psychological intervention despite physical recovery.

5. Significance and Clinical Implications

• Personalized Rehabilitation: Clinicians should monitor both PROs at multiple time points. If a mismatch is detected (e.g., high function/low readiness), the rehabilitation plan must be adjusted to include specific psychological interventions (e.g., exposure therapy, confidence building) rather than just physical loading.
• Timing of Intervention: The study suggests that psychological recovery may lag behind physical recovery in some athletes. Interventions should not wait until the end of rehab but should be integrated early (starting around 3.5 months) to ensure parallel progression.
• Risk Mitigation: Understanding the parallel nature of these domains helps prevent "overconfidence" injuries. If an athlete reports high readiness but low functional scores, the clinician knows to hold RTS clearance.
• Limitations & Future Directions:
  • The study was limited to two time points; future research should include longitudinal tracking beyond 7 months.
  • The sample size was smaller than the a priori calculation for a weak correlation, though sufficient for the observed moderate effect.
  • Future studies should investigate if specific "mismatch" profiles predict higher reinjury rates.

Conclusion: The study concludes that psychological readiness and subjective knee function progress in parallel from 3.5 to 7 months post-ACLR. This concordance supports a holistic rehabilitation approach where physical and psychological components are addressed simultaneously to optimize Return to Sport outcomes.