Accelerated Versus Traditional Rehabilitation After Anterior Cruciate Ligament Reconstruction

Anterior cruciate ligament (ACL) injuries are common, especially among athletes. These injuries often require surgical reconstruction followed by a comprehensive rehabilitation program to restore knee function and allow individuals to return to their desired activity levels. Traditionally, rehabilitation after ACL reconstruction involved prolonged periods of immobilization and gradual increases in activity. However, in recent years, accelerated rehabilitation protocols have gained popularity, aiming to expedite the recovery process. This article evaluates the evidence for accelerated versus traditional rehabilitation protocols after ACL reconstruction, discusses criteria for returning to sport, and explores the risk of reinjury.

Comparing Accelerated and Traditional Rehabilitation Protocols

What is an Accelerated Rehabilitation Protocol?

Accelerated rehabilitation protocols after ACL reconstruction emphasize early weight-bearing, range of motion exercises, and a faster progression to more demanding activities1. The goal is to restore knee function and potentially facilitate a quicker return to sport compared to traditional approaches1. However, it's important to note that individual outcomes may vary.

Some surgeons utilize a "Short Graft Technique" with accelerated rehabilitation protocols2. This technique offers several potential benefits, including:

  1. Use of only one hamstring tendon rather than two for the graft.
  2. Larger graft size, which may reduce the chance of re-injury.
  3. Stronger fixation, allowing for earlier rehabilitation and walking.
  4. Less traumatic surgical technique, potentially leading to less pain and quicker recovery.

What is a Traditional Rehabilitation Protocol?

Traditional rehabilitation protocols typically involve a more conservative approach, with a longer period of immobilization and a slower progression to more demanding activities1. These protocols often focus on protecting the healing graft and gradually increasing stress on the knee joint1.

Evidence for Accelerated vs. Traditional Rehabilitation

A meta-analysis by 1 examined the outcomes of accelerated and non-accelerated rehabilitation after ACL reconstruction using hamstring autografts. The analysis showed that accelerated rehabilitation may lead to better early subjective clinical outcomes, but it might also be associated with a slightly higher risk of tunnel widening and anterior instability. However, these differences were not considered clinically significant.

Another meta-analysis by 3 compared delayed versus accelerated weight-bearing rehabilitation protocols. This analysis indicated a potential increase in knee laxity with accelerated weight-bearing. However, it found no significant differences in knee function, quadriceps strength, or range of motion between the two groups at a follow-up within 2 years.

A study by 4 found that an accelerated rehabilitation program resulted in improved range of motion and strength gains without compromising stability.

Overall, the evidence suggests that accelerated rehabilitation protocols can potentially lead to faster recovery of knee function and an earlier return to sport compared to traditional approaches. However, there may be a slightly increased risk of knee laxity and tunnel widening with accelerated protocols.

Exclusionary Criteria for Accelerated Rehabilitation

It's important to note that not all patients are suitable candidates for accelerated rehabilitation protocols5. Some exclusionary criteria include:

  1. Concomitant meniscal repair
  2. Concomitant reconstruction of another ligament
  3. Concomitant patellofemoral realignment procedure
  4. ACL revision reconstruction
  5. MRI evidence of severe bone bruising or articular cartilage damage

Criteria for Return to Sport

The decision to return to sport after ACL reconstruction should be made on an individual basis, considering various factors such as the type of graft used, the patient's healing progress, and the demands of their sport6. There is no single set of criteria that applies to all athletes6. However, some common factors that are typically considered include:

Range of Motion

Full range of motion, including full extension and flexion, is essential for normal knee function and should be achieved before returning to sport6.

Effusion

Minimal to no swelling in the knee joint is crucial7.

Strength

Adequate strength in the quadriceps and hamstring muscles is necessary to support the knee joint and prevent re-injury6. Limb symmetry index (LSI) for quadriceps strength should be >80%8. It's important to note that the return of quadriceps strength can vary significantly depending on the type of graft used and individual healing rates7. Regular objective testing of quadriceps strength is crucial to assess knee function, and a 12-month post-ACLR criterion may be inadequate for return to running7.

Joint Laxity

The knee joint should be stable, with no signs of excessive laxity6.

Functional Performance

Athletes should be able to perform sport-specific movements and activities without pain or instability6. This may involve hop tests, agility drills, and other functional assessments7. To effectively assess return-to-play readiness, testing should be dynamic, reactive, and simulate the chaotic circumstances of the sporting environment9.

Return to Running Criteria

Specific criteria are often used to guide the return to running after ACL reconstruction. These may include:

  1. 95% knee flexion range of motion
  2. Full extension ROM
  3. No pain or swelling 8

Return to Activity Criteria

In addition to the criteria mentioned above, the following factors may be considered for return to more demanding activities:

  1. LSI >80% for quadriceps strength
  2. LSI >80% eccentric impulse during countermovement jump
  3. Pain-free aqua jogging and Alter-G running
  4. Pain-free repeated single-leg hopping ("pogos") 8

Psychological Readiness

Athletes should be mentally prepared to return to sport and have confidence in their knee6. Addressing kinesiophobia (fear of movement) is also crucial6. Athletes should not only meet physical criteria but also be mentally prepared and confident in their knee's stability before returning to sport.

Risk of Reinjury

Despite successful ACL reconstruction and rehabilitation, there is still a risk of re-injury10. Several factors can contribute to this risk, including:

  1. Age: Younger athletes, particularly those under 25, are at higher risk11.
  2. Activity level: Athletes who participate in high-demand sports that involve pivoting and cutting movements are at greater risk11.
  3. Graft choice: The type of graft used in the reconstruction can influence the re-tear rate11.
  4. Surgical technique: Proper graft placement, tensioning, and fixation are essential to minimize the risk of re-injury11.
  5. Rehabilitation compliance: Adhering to a structured rehabilitation program is crucial for a successful recovery and reducing the risk of re-injury11.
  6. Neuromuscular control: Deficits in neuromuscular control can lead to improper movement patterns that increase stress on the knee12.
  7. Early return to sport: Returning to sport before the knee has fully healed and regained strength and stability increases the risk of re-injury12. Studies have shown that early return to sport (less than 10 months) is associated with an increased risk of bone marrow lesions, which can contribute to the development of osteoarthritis13.
  8. Knee-extension and quadriceps strength symmetry: Greater knee-extension symmetry at 6 months and increased quadriceps strength symmetry in patients returning to activity before 8 months have been linked to a higher probability of reinjury10.
  9. Concomitant injuries: Patients with concomitant meniscus injury or posterior cruciate ligament injury have a significantly higher risk of knee reinjury14.
  10. Other factors: Poor movement patterns, overcompensation, inadequate strength training, larger Q angle, hyper-mobility, hip and ankle mobility restrictions or instability, and lack of core stability can also contribute to ACL re-injury15.

While both accelerated and traditional rehabilitation protocols aim to minimize the risk of reinjury, they have distinct advantages and disadvantages that should be considered when choosing the most appropriate approach.

Accelerated vs. Traditional Rehabilitation: Benefits and Drawbacks

| Feature | Accelerated Rehabilitation |

Works cited

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2. Accelerated Rehabilitation Guidelines ACL Reconstruction with The Short Graft Technique - Brisbane Knee and Shoulder Clinic, accessed February 17, 2025, /images/press/uploads/Accelerated-short-graft-ACL.pdf

3. Delayed versus Accelerated Weight-bearing Rehabilitation Protocol ..., accessed February 17, 2025, https://pubmed.ncbi.nlm.nih.gov/35037693/

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8. Clinical Practice Guideline on Rehabilitation after ACLR - Aspetar, accessed February 17, 2025, https://www.aspetar.com/en/professionals/aspetar-clinical-guidelines/recommendations-on-rehabilitation-after-aclr

9. The Need To Change Return to Play Testing in Athletes Following ACL Injury: A Theoretical Model, accessed February 17, 2025, https://ijspt.scholasticahq.com/article/67988-the-need-to-change-return-to-play-testing-in-athletes-following-acl-injury-a-theoretical-model

10. Predicting Anterior Cruciate Ligament Reinjury From Return-to-Activity Assessments at 6 Months Postsurgery: A Prospective Cohort Study, accessed February 17, 2025, https://pmc.ncbi.nlm.nih.gov/articles/PMC9020598/

11. Understanding the Risk of ACL Retear After Reconstruction: What You Need to Know, accessed February 17, 2025, https://www.princetonmedicine.com/blog/understanding-the-risk-of-acl-retear-after-reconstruction-what-you-need-to-know

12. ACL Rehabilitation: Re-injury and Return to Sport Tests - Physiopedia, accessed February 17, 2025, https://www.physio-pedia.com/ACL_Rehabilitation:_Re-injury_and_Return_to_Sport_Tests

13. Return to Play after ACL Surgery, What is Appropriate?, accessed February 17, 2025, https://www.totalorthosportsmed.com/return-to-play-after-acl-surgery-what-is-appropriate/

14. Risk factors of knee reinjury after anterior cruciate ligament reconstruction - PubMed, accessed February 17, 2025, https://pubmed.ncbi.nlm.nih.gov/38195945/

15. Risk Factors For ACL Tears - Sano Orthopedics, accessed February 17, 2025, https://sanokc.com/risk-factors-acl-tears/