What are examples of closed kinetic chain (CKC) exercises versus open kinetic chain (OKC) exercises for a patient with lateral quadriceps pain following a meniscus or ligament injury?

Closed vs. Open Kinetic Chain Exercises for Lateral Quadriceps Pain After Meniscus/Ligament Injury

Both closed kinetic chain (CKC) and open kinetic chain (OKC) exercises should be used together for optimal quadriceps strengthening, with CKC exercises prioritized early (starting week 2) and OKC exercises added from week 4 onward in a restricted range of motion (90°-45°) to minimize anterior knee pain while maximizing strength gains. 1

Definitions and Biomechanical Differences

Closed Kinetic Chain (CKC) Exercises:

• The distal segment (foot) is fixed against a surface or resistance, creating a closed system where movement at one joint produces movement at adjacent joints 2
• Examples include: squats, leg press, lunges, step-ups, wall sits, and single-leg balance exercises 1, 2
• Generate approximately twice as much hamstring co-contraction compared to OKC exercises, providing dynamic knee stabilization 2
• Produce greatest quadriceps activity when the knee is near full flexion 2
• Create higher posterior cruciate ligament tension (approximately twice that of OKC) but no anterior cruciate ligament strain 2
• Result in greatest patellofemoral compressive force near full knee flexion 2

Open Kinetic Chain (OKC) Exercises:

• The distal segment (foot) moves freely in space without fixed resistance 2, 3
• Examples include: seated knee extensions, straight leg raises, prone hamstring curls, and supine hip flexion 1, 2
• Produce more rectus femoris activity while CKC produces more vasti muscle activity 2
• Generate greatest quadriceps activity when the knee is near full extension 2
• Create anterior cruciate ligament tension only near full extension 2
• Result in peak patellofemoral compressive force in the mid-range of knee extension 2

Clinical Application for Lateral Quadriceps Pain

Early Phase (Weeks 1-3)

Start with isometric exercises immediately:

• Static quadriceps contractions and straight leg raises can be safely prescribed during the first 2 postoperative weeks 1
• These confer advantages for faster recovery of knee range of motion at 1 month without compromising stability 1
• Perform only if they provoke no pain 1

Introduce CKC exercises from week 2:

• CKC exercises can be safely performed from week 2 postoperative 1, 4
• Starting leg press at 3 weeks can improve subjective knee function and functional outcomes 1
• CKC exercises produce less anterior knee pain compared to OKC exercises, making them ideal for patients with lateral quadriceps pain 1

Intermediate Phase (Weeks 4-8)

Add OKC exercises with strict range restrictions:

• OKC exercises can be performed from week 4 postoperative in a restricted ROM of 90°-45° 1
• Progress ROM gradually: 90°-30° in week 5,90°-20° in week 6,90°-10° in week 7, and full ROM by week 8 1, 4
• This restricted range minimizes ACL graft strain and patellofemoral stress 1, 3

Critical consideration for graft type:

• For hamstring grafts, OKC exercises can start at 4 weeks in 90°-45° ROM, but no extra weight should be added in the first 12 weeks to prevent graft elongation 1
• For bone-patellar tendon-bone grafts, extra resistance can be added at a leg extension machine from week 4 1
• Hamstring grafts are more vulnerable to early introduction of OKC compared to BTB grafts 1

Advanced Phase (Beyond 8 Weeks)

Combine both exercise types for optimal outcomes:

• Evidence recommends the use of both OKC and CKC exercises post-injury for regaining quadriceps strength 1
• A combination of OKC and CKC exercises results in better strength and return to play than CKC alone 1, 5
• Patients training with both CKC plus OKC exercises show significantly greater quadriceps torque improvement without reducing knee joint stability 5
• Adding OKC to CKC leads to a significantly higher number of athletes returning to their previous activity level 2 months earlier 5

Evidence-Based Advantages and Disadvantages

CKC Exercise Advantages:

• Less anterior knee pain compared to OKC exercises 1
• Less risk of increased laxity 1
• Better self-reported knee function in early phases 1
• More functional for weight-bearing activities 3
• Greater hamstring co-contraction providing dynamic stability 2

OKC Exercise Advantages:

• Superior for improving quadriceps strength at 3-4 months post-injury 6
• Patients adding OKC exercises increased quadriceps torque significantly more than CKC alone 5
• More effective for isolated quadriceps strengthening 3
• Allows targeted strengthening in pain-free ranges 1

Key Disadvantages to Monitor:

• OKC exercises might induce more anterior knee pain compared to CKC exercises 1
• Early OKC (before week 4) may increase laxity, particularly with hamstring grafts 1
• OKC creates ACL tension near full extension, requiring ROM restrictions 2

Common Pitfalls and How to Avoid Them

Pitfall 1: Starting OKC too early

• There is no evidence supporting OKC exercises earlier than the fourth week after surgery 1
• Starting OKC at 4 weeks versus 12 weeks shows no differences in laxity, strength, pain, ROM, knee function, or balance 1

Pitfall 2: Using full ROM with OKC exercises prematurely

• Always restrict OKC to 90°-45° initially to minimize ACL strain and patellofemoral stress 1
• Progress ROM only according to the weekly schedule outlined above 1, 4

Pitfall 3: Abandoning CKC exercises once OKC is introduced

• Both exercise types are necessary for optimal outcomes 1
• CKC exercises should continue throughout rehabilitation for functional strength and reduced pain 1, 3

Pitfall 4: Ignoring pain signals

• Anterior knee pain should be monitored closely, with load progression adjusted accordingly 1
• If pain increases, reduce resistance or ROM rather than eliminating the exercise entirely 1

Specific Algorithm for Lateral Quadriceps Pain

1. Week 1-2: Isometric quadriceps exercises only (straight leg raises, quad sets) if pain-free 1

2. Week 2-4: Add CKC exercises (leg press, mini squats, wall sits) while continuing isometrics 1, 4

3. Week 4: Introduce OKC exercises in 90°-45° ROM, maintaining CKC exercises 1

4. Week 5-8: Progressively expand OKC ROM weekly while increasing CKC resistance 1, 4

5. Beyond 8 weeks: Full ROM for both exercise types, progressing to eccentric and plyometric training 1, 7

6. Monitor: If anterior knee pain increases, prioritize CKC over OKC temporarily 1

Strength and Functional Outcomes

• No significant differences exist in anterior tibial laxity between OKC and CKC exercises when performed correctly 1
• No differences in subjective knee function, ROM, atrophy, or functional activities between exercise types 1
• Both types of exercise improve functional activities equally 1
• The combination approach yields superior quadriceps strength gains compared to either method alone 5, 6