What is the effect of seated leg extensions on patellar tendinopathy?

Seated Leg Extensions and Patellar Tendinopathy

Seated leg extensions (open kinetic chain exercises) can be safely used in patellar tendinopathy rehabilitation without compromising outcomes, though they should not replace eccentric strengthening exercises as the primary treatment modality. 1

Evidence for Open Kinetic Chain Exercises in Knee Rehabilitation

The most relevant evidence comes from ACL reconstruction rehabilitation studies, which directly examined seated knee extensions in populations with patellar tendon concerns:

• No differences were found between starting open kinetic chain exercises (including seated leg extensions) early versus late in terms of laxity, strength, pain, range of motion, knee function, functional activities, and balance. 1

• When comparing open versus closed kinetic chain exercises across nine studies, there was no significant difference in anterior tibial laxity, subjective knee function, range of motion, atrophy, or functional activities. 1

• Anterior knee pain should be monitored when using seated leg extensions, with load progressed cautiously based on symptoms. 1

Primary Treatment Approach for Patellar Tendinopathy

While seated leg extensions are not contraindicated, they should not be your primary intervention:

• Eccentric strengthening exercises remain the cornerstone of treatment, as they reduce symptoms, increase strength, and promote tendon healing by stimulating collagen production and guiding normal alignment of newly formed collagen fibers. 1, 2, 3

• Load-management strategies combined with progressive tendon loading through eccentric exercises are the most effective treatment options. 4

• Eccentric training has the strongest available evidence for any patellar tendinopathy treatment, with a 2012 systematic review finding "strong evidence" for this approach. 3

Practical Implementation Algorithm

If using seated leg extensions in patellar tendinopathy:

1. Begin with limited range of motion (90° to 45° knee flexion) to reduce patellar tendon stress. 1

2. Progress range gradually only if pain remains controlled (e.g., week 1: 90° to 45°, week 2: 90° to 20°, week 3: 90° to 0°). 1

3. Monitor for anterior knee pain at each session—if pain increases, reduce range or load immediately. 1

4. Use seated leg extensions as a supplementary exercise only, not as replacement for eccentric loading protocols. 2, 3

Critical Pitfalls to Avoid

• Do not use seated leg extensions as monotherapy—they lack the specific eccentric loading stimulus that drives tendon healing. 2, 3

• Avoid complete immobilization or complete rest, as this causes muscular atrophy and deconditioning. 2, 3

• Never inject corticosteroids directly into the tendon substance when pain persists, as this inhibits healing, reduces tensile strength, and predisposes to spontaneous rupture. 3

Additional Evidence-Based Interventions

• Adding static stretching exercises to eccentric training produces superior results compared to eccentric training alone, with significant differences maintained at 6-month follow-up. 5

• Deep transverse friction massage reduces pain and may provide additional benefit when combined with eccentric exercises. 1, 3

• Relative rest to decrease repetitive loading (especially jumping and stair navigation) is essential, but complete immobilization should be avoided. 2, 3

• Approximately 80% of patients recover completely within 3-6 months with appropriate conservative treatment centered on eccentric loading. 3