What are the potential causes and treatment options for a patient with tenderness to the muscle behind the patella (kneecap), considering factors such as age, medical history, and onset of symptoms?

Tenderness to Muscle Behind Patella: Patellar Tendinopathy

Direct Answer

You are dealing with patellar tendinopathy, and the patient should immediately begin eccentric strengthening exercises combined with relative rest and scheduled NSAIDs for pain control. 1

Differential Diagnosis and Clinical Confirmation

The "muscle behind patella" tenderness most likely represents patellar tendinopathy affecting the patellar tendon at its insertion on the inferior pole of the patella. 1, 2

Key Physical Examination Findings to Confirm:

• Well-localized tenderness at the inferior pole of the patella on palpation 3, 1
• Pain reproduction with resisted leg extension in full extension 1, 2
• Positive decline squat test (places increased load on patellar tendon and reproduces pain) 1, 2
• Look for muscle atrophy suggesting chronicity 3
• Joint effusions are uncommon and suggest intra-articular pathology instead 3

History Pattern:

• Insidious onset of load-related pain coinciding with increased activity 3
• Pain described as "sharp" or "stabbing" 3
• Early stages: pain during activity that may subside after warm-up 3
• Later stages: pain present at rest and increasing in intensity 3
• Aggravated by jumping, stairs, and prolonged sitting 2

First-Line Treatment Protocol

1. Eccentric Strengthening Exercises (Cornerstone of Treatment)

This is the most important intervention with the strongest evidence. 1, 4

Specific Exercise Prescription: 1

• Train quadriceps and surrounding muscles 2-3 days per week
• Use 60-70% of one-repetition maximum for moderate to hard intensity
• Perform 8-12 repetitions across 2-4 sets
• Rest 2-3 minutes between sets
• Allow at least 48 hours rest between training sessions for the same muscle group

Mechanism: Eccentric exercises reduce symptoms, increase strength, and promote tendon healing by stimulating collagen production and guiding normal alignment of newly formed collagen fibers. 1

2. Relative Rest (Not Complete Immobilization)

Reduce repetitive loading activities that reproduce pain (particularly jumping and stair navigation), but maintain general activity. 1, 5

Critical Pitfall: Avoid complete immobilization—this causes muscular atrophy and deconditioning. 1, 5

3. Pain Management

NSAIDs (oral or topical): 1

• Provide short-term pain relief but do not affect long-term outcomes 3, 1
• Topical NSAIDs are preferable due to elimination of gastrointestinal hemorrhage risk 1, 5

Cryotherapy: 1

• Apply through a wet towel for 10-minute periods for acute pain relief

4. Adjunctive Manual Therapy

Deep transverse friction massage reduces pain and may provide additional benefit. 1, 2

Secondary Treatment Options (If Initial Management Insufficient)

Corticosteroid Iontophoresis

Effective for treating patellar tendon pain and improving function. 1

Critical Pitfall: Never inject corticosteroids directly into the tendon substance—this inhibits healing, reduces tensile strength, and predisposes to spontaneous rupture. 1, 5

Extracorporeal Shock Wave Therapy

Safe and noninvasive option for chronic cases unresponsive to initial management. 3, 5

Patellar Taping

Consider medially directed patellar taping for short-term relief when rehabilitation is hindered by elevated symptom severity. 1

Imaging Considerations

Imaging is NOT routinely needed for diagnosis but may be considered if: 3

• Diagnosis remains unclear after thorough history and physical examination
• Pain is recalcitrant despite adequate conservative management
• Preoperative evaluation is needed

If imaging is pursued: 1

• Ultrasonography: More specific (94%) than sensitive (58%) for showing tendon thickening and decreased echogenicity
• MRI: Moderate sensitivity (78%) and specificity (86%) for demonstrating chronic degenerative changes

Expected Timeline and Outcomes

Approximately 80% of patients recover completely within 3-6 months with appropriate conservative treatment. 1, 2, 5

When to Consider Surgery

Surgery is justified only after 3-6 months of well-managed conservative treatment has failed. 1, 2, 5

Surgical techniques include: 1, 2

• Open or arthroscopic excision of abnormal tendinous tissue
• Longitudinal tenotomies to release areas of scarring and fibrosis

Critical Pitfalls to Avoid

1. Do not proceed to surgery without an adequate 3-6 month trial of conservative treatment 1, 2, 5
2. Avoid multiple corticosteroid injections—they weaken tendon structure despite short-term symptom relief 1, 5
3. If multiple tendons are symptomatic, evaluate for underlying rheumatic disease 3, 1
4. Do not completely immobilize—maintain activity to prevent deconditioning 1, 5

Age-Specific Considerations

In children (particularly age 7 or younger): 5

• Patellar tendinitis is uncommon at this age
• Consider alternative diagnoses including apophysitis (Osgood-Schlatter disease or Sinding-Larsen-Johansson syndrome) or inflammatory conditions
• If patellar tendinopathy is confirmed, use the same conservative approach with particular caution regarding corticosteroid use

In adolescents and adults >50 years: 3

• If acute trauma preceded symptoms, consider radiographs per Ottawa or Pittsburgh rules to exclude fracture
• Look for patellar dislocation if suspected (radiographs indicated) 3