Patellar Tendinopathy (Jumper's Knee)

1. Clinical Overview

Summary

Patellar tendinopathy, commonly known as Jumper's Knee, is a chronic overuse injury characterized by activity-related anterior knee pain localized to the inferior pole of the patella. [1] The condition predominantly affects athletes in jumping sports (basketball, volleyball) and runners, with prevalence rates reaching 45% in elite volleyball players. [2] Despite the traditional nomenclature "tendonitis," the underlying pathology is degenerative (tendinosis) rather than inflammatory, characterized by collagen disorganization, increased mucoid ground substance, neovascularisation, and an absence of inflammatory cells on histology. [3]

The hallmark clinical feature is well-localized tenderness at the inferior pole of the patella, exacerbated by jumping, landing, squatting, and prolonged sitting ("movie sign"). [4] Diagnosis is primarily clinical, though imaging modalities (ultrasound, MRI) can confirm structural abnormalities including tendon thickening, hypoechoic regions, and neovascularisation on Doppler studies. [5]

Management is predominantly conservative, with eccentric loading exercises (specifically single-leg decline squats) representing the gold-standard treatment with Level I evidence demonstrating 70-80% improvement at 12 weeks. [6,7] Adjunctive therapies include heavy slow resistance training, isometric exercises for pain modulation, and in refractory cases, extracorporeal shockwave therapy (ESWT) or platelet-rich plasma (PRP) injections. [8,9] Corticosteroid injections are absolutely contraindicated due to the risk of tendon rupture and acceleration of degenerative changes. [10] Surgical intervention (arthroscopic or open debridement) is reserved for cases refractory to 6-12 months of conservative management, with success rates of 60-90% but prolonged rehabilitation. [11]

Key Facts

• Definition: Chronic degenerative tendinopathy of the patellar tendon, typically at the inferior pole attachment
• Pathology: Tendinosis (degenerative), NOT tendonitis (inflammatory)
• Epidemiology: 14% basketball players, 45% volleyball players; peak age 15-30 years
• Location: 75% inferior patellar pole, 20% mid-tendon, 5% tibial insertion
• Gold Standard Imaging: Ultrasound (dynamic assessment) or MRI (structural detail)
• Gold Standard Treatment: Eccentric decline squats (single-leg, 25° decline, 12 weeks)
• Outcome Measure: VISA-P score (Victorian Institute of Sport Assessment - Patella)
• Contraindication: Corticosteroid injections (rupture risk)
• Surgery: Only after 6-12 months failed conservative treatment

Clinical Pearls

"Tendinosis, Not Tendonitis": Histology shows collagen disorganization and mucoid degeneration with NO inflammatory cells. The term "tendinopathy" is preferred as it encompasses the degenerative pathology. [3]

"Decline Squats Are Gold Standard": Single-leg decline squats on a 25° decline board (3 sets × 15 reps, twice daily, 12 weeks) have the strongest evidence base with 70-80% success rates. [6,7]

"No Steroids, Ever": Corticosteroid injections are contraindicated—they cause collagen necrosis, reduce tensile strength by 35-50%, and significantly increase rupture risk. [10]

"VISA-P Tracks Progress": The VISA-P questionnaire (0-100, higher = better) is the validated outcome measure for patellar tendinopathy and should be assessed at baseline and throughout treatment. [12]

"Chronic and Frustrating": Patellar tendinopathy is notoriously slow to heal (often 3-6 months), requires strict adherence to loading protocols, and has high recurrence rates if athletes return to sport prematurely. [1]

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2. Epidemiology

Incidence and Prevalence

Patellar tendinopathy is one of the most common overuse injuries in athletes, particularly those in jumping and running sports:

Incidence in Jumping Athletes: Longitudinal studies show an incidence of 2.5 cases per 1000 athletic exposures in volleyball and basketball. [2]

Demographics

Risk Factors

Exam Detail: #### Intrinsic Factors

Extrinsic Factors

Natural History

Without treatment:

• Stage 1 (pain after activity only): May persist months without progression
• Stage 2 (pain during activity, no performance limitation): Progressive over 6-12 months
• Stage 3 (pain limiting performance): Often requires cessation of sport
• Stage 4 (tendon rupture): Rare (less than 1%), but risk increased with corticosteroid use [10]

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3. Aetiology and Pathophysiology

Failed Healing Response Model

The contemporary understanding of patellar tendinopathy centers on a failed healing response to repetitive mechanical loading that exceeds the tendon's capacity for adaptation and repair. [3,16]

Exam Detail: #### Pathological Cascade

┌──────────────────────────────────────────────────────────────┐
│   PATELLAR TENDINOPATHY PATHOGENESIS                          │
├──────────────────────────────────────────────────────────────┤
│                                                              │
│  1. REPETITIVE LOADING                                       │
│     └─ Jumping, landing (5-10× body weight forces)          │
│     └─ Exceeds tendon repair capacity                       │
│                                                              │
│  2. MICROTRAUMA                                              │
│     └─ Collagen fiber microtears                            │
│     └─ Inadequate recovery between loads                    │
│                                                              │
│  3. FAILED HEALING                                           │
│     └─ Attempted repair → disordered collagen               │
│     └─ Type I → Type III collagen shift                     │
│     └─ Increased mucoid ground substance                    │
│                                                              │
│  4. STRUCTURAL DEGENERATION                                  │
│     └─ Collagen disorganization (loss of crimp)             │
│     └─ Neovascularisation (VEGF upregulation)               │
│     └─ Neural ingrowth (substance P, CGRP)                  │
│     └─ Tenocyte apoptosis                                   │
│                                                              │
│  5. BIOMECHANICAL COMPROMISE                                 │
│     └─ Reduced tensile strength (30-40% decrease)           │
│     └─ Increased tendon thickness (compensatory)            │
│     └─ Altered mechanical properties                        │
│                                                              │
│  6. PAIN AND DYSFUNCTION                                     │
│     └─ Neurogenic pain (substance P, glutamate)             │
│     └─ Mechanical pain (abnormal loading)                   │
│     └─ Activity limitation                                  │
│                                                              │
└──────────────────────────────────────────────────────────────┘

Cellular and Molecular Pathology

Histopathological Features: [3]

• Collagen disorganization: Loss of parallel alignment, disrupted crimp pattern
• Hypercellularity: Initially increased tenocytes, then apoptosis in chronic stages
• Neovascularisation: Abnormal capillary ingrowth from peritendinous tissue (normally avascular)
• Neural ingrowth: Unmyelinated sensory neurons accompany new vessels
• Mucoid degeneration: Increased glycosaminoglycans (GAGs), proteoglycans
• Calcification: Dystrophic calcification in chronic cases (10-15%)
• Absence of inflammatory cells: No neutrophils, macrophages, or lymphocytes on histology

Molecular Mediators:

• Matrix metalloproteinases (MMPs): Upregulated MMP-9, MMP-13 → collagen degradation
• VEGF (Vascular Endothelial Growth Factor): Drives neovascularisation
• Substance P: Neurogenic inflammation, pain signaling
• Glutamate: Elevated in painful tendons, NMDA receptor activation
• Prostaglandin E2: Minimal (confirms non-inflammatory nature)

Biomechanical Factors

Patellar Tendon Loading:

• Walking: 0.5× body weight
• Running: 4-5× body weight
• Jumping: 6-8× body weight
• Landing from height: 10-12× body weight

Highest stress concentration: Occurs at the osteotendinous junction (inferior patellar pole), explaining the predilection for pathology at this site. [16]

Location of Pathology

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4. Clinical Presentation

Symptoms

Chief Complaint

Patients typically present with anterior knee pain localized to the inferior pole of the patella, with gradual onset over weeks to months. [4]

Functional Impact

• "Movie sign": Pain after prolonged sitting with knee flexed (increased patellar tendon stretch)
• "First step pain": Pain with initial loading after rest
• Sports performance: Initially only after activity, progressing to during and limiting performance

Blazina Classification (Severity Staging)

Exam Detail: ### VISA-P Questionnaire

The Victorian Institute of Sport Assessment - Patella (VISA-P) is the validated outcome measure for patellar tendinopathy. [12]

Scoring:

• 0-100 points (100 = asymptomatic)
• less than 50: Severe symptoms
• 50-79: Moderate symptoms
• 80-100: Mild symptoms

Domains:

• Pain with activities (sitting, squatting, jumping)
• Functional ability
• Sports participation

Interpretation:

• Baseline: Typically 40-60 in symptomatic athletes
• Minimal clinically important difference (MCID): 13 points
• Successful treatment: Increase ≥20 points or score ≥80

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5. Clinical Examination

Inspection

• Usually normal appearance (no effusion, erythema)
• May observe quadriceps wasting in chronic cases (measure thigh circumference 15cm proximal to superior patellar pole)
• Occasionally visible swelling at inferior patellar pole

Palpation

Key Finding: Exquisite point tenderness at the inferior pole of the patella, best elicited with the knee in full extension (relaxes quadriceps, allows patellar mobilization). [4]

Technique:

1. Patient supine, knee extended
2. Push patella proximally to expose inferior pole
3. Palpate inferior pole with thumb
4. Positive test: Focal tenderness at inferior pole (patient can often point with one finger)

Differential palpation:

• Patellofemoral pain: Diffuse peripatellar tenderness
• Prepatellar bursitis: Swelling over anterior patella
• Fat pad impingement: Medial/lateral to patellar tendon
• Osgood-Schlatter: Tibial tubercle tenderness (adolescents)

Functional Tests

Range of Motion

• Typically full passive range of motion (cf. arthropathy)
• Pain may limit deep flexion (> 90°) due to tendon stretch

Neurovascular Examination

• Normal (excludes neuropathy, vascular pathology)

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6. Differential Diagnosis

Exam Detail: | Condition | Key Distinguishing Features | Examination Findings | |-----------|----------------------------|---------------------| | Patellofemoral pain syndrome | Diffuse anterior knee pain, retropatellar; worse with stairs, prolonged sitting | Diffuse peripatellar tenderness, positive patellar grind test, no focal inferior pole tenderness | | Fat pad impingement (Hoffa syndrome) | Pain medial/lateral to patellar tendon; history of hyperextension | Tenderness medial/lateral to tendon, positive Hoffa test (pain with passive hyperextension + compression) | | Prepatellar bursitis | Swelling over anterior patella; kneeling history | Fluctuant swelling over patella, no tendon tenderness | | Quadriceps tendinopathy | Pain at superior pole of patella | Tenderness superior patellar pole (proximal to patella) | | Osgood-Schlatter disease | Adolescents (10-15 years), tibial tubercle pain | Tibial tubercle swelling and tenderness, open growth plate on X-ray | | Sinding-Larsen-Johansson syndrome | Adolescents, inferior patellar pole pain | Inferior pole tenderness, fragmentation on X-ray, age 10-14 years | | Patellar tendon rupture | Acute onset, audible pop, inability to extend knee | Palpable gap, patella alta, inability to straight leg raise | | Patella stress fracture | Insidious onset, no focal tendon tenderness | Bony tenderness, positive percussion test, MRI shows fracture line | | Meniscal pathology | Joint line pain, mechanical symptoms (clicking, locking) | McMurray's positive, joint line tenderness |

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7. Investigations

Imaging

Diagnosis of patellar tendinopathy is primarily clinical. Imaging is used to:

• Confirm diagnosis when clinical findings are equivocal
• Assess severity and extent of pathology
• Guide interventional procedures (e.g., PRP injection)
• Exclude differential diagnoses

X-ray (Plain Radiograph)

Indications: Initial investigation to exclude bony pathology

Other findings:

• Elongated patella: Increased patellar length (minor association with tendinopathy)
• Osteophytes: At inferior pole in chronic cases

Ultrasound

First-line imaging modality due to dynamic assessment, low cost, and absence of radiation. [5]

Normal patellar tendon:

• Homogeneous hyperechoic (bright) fibrillar pattern
• Thickness: 3-4mm (measured 1cm distal to inferior pole)
• No vascularity on Doppler

Abnormal findings in tendinopathy:

Grading (Ultrasound Tissue Characterization - UTC):

• Grade 1: Intact, organized fibrillar structure
• Grade 2: Discontinuous, less organized fibers
• Grade 3: Mainly amorphous matrix with disrupted fibers
• Grade 4: Amorphous tissue, cellular debris

MRI

Indications:

• Equivocal ultrasound
• Pre-operative planning
• Suspected alternative pathology (bone stress, meniscal tear)

Sequences: T1, T2, PD fat-sat (best for tendon pathology)

Abnormal findings:

MRI grading (Blazina adapted):

• Grade 1: Normal signal, normal size
• Grade 2: Focal areas increased signal, normal/minimally increased size
• Grade 3: Diffuse increased signal, moderately increased size
• Grade 4: Complete rupture

Power Doppler Ultrasound

Neovascularisation (abnormal blood vessel ingrowth) is a feature of tendinopathy and can be quantified using Power Doppler:

• Modified Öhberg score (0-4):
  • 0: No flow
  • 1: Minimal flow (1-2 vessels)
  • 2: Moderate flow
  • 3: Marked flow
  • 4: Extreme vascularity

Clinical correlation: Controversial whether neovascularisation correlates with pain; some studies suggest vessels accompany sensory nerves. [5]

Laboratory Tests

Not routinely indicated (diagnosis is clinical/imaging)

Consider in atypical presentations:

• ESR, CRP: To exclude inflammatory arthropathy, infection
• Rheumatoid factor, anti-CCP: If polyarticular symptoms
• HLA-B27: If associated axial symptoms (seronegative spondyloarthropathy can cause enthesopathy)

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8. Classification and Staging

Blazina Classification (Clinical Staging)

Victorian Institute of Sports Assessment - Patella (VISA-P)

Gold standard outcome measure for symptom severity and treatment response. [12]

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9. Management

Principles

1. Load management: Reduce tendon load below pain threshold
2. Structured loading: Progressive tendon loading to stimulate collagen remodeling
3. Address biomechanical deficits: Hip strength, ankle mobility
4. Avoid harmful interventions: No corticosteroid injections
5. Patience: Tendon healing is slow (3-6 months minimum)

Exam Detail: ### Treatment Algorithm

┌────────────────────────────────────────────────────────────────┐
│   PATELLAR TENDINOPATHY MANAGEMENT PATHWAY                      │
├────────────────────────────────────────────────────────────────┤
│                                                                │
│  DIAGNOSIS: Clinical + Imaging                                 │
│  BASELINE: VISA-P score                                        │
│                                                                │
│  ┌──────────────────────────────────────────────────┐          │
│  │  FIRST-LINE: Conservative (3-6 months)            │          │
│  ├──────────────────────────────────────────────────┤          │
│  │  1. LOAD MANAGEMENT                               │          │
│  │     • Reduce/cease jumping activities              │          │
│  │     • Modify training volume (50% reduction)       │          │
│  │     • Pain monitoring (≤3/10 during exercise)      │          │
│  │                                                   │          │
│  │  2. ECCENTRIC LOADING (GOLD STANDARD)              │          │
│  │     • Single-leg decline squat (25° board)         │          │
│  │     • 3 sets × 15 reps, twice daily                │          │
│  │     • 12-week protocol (Visnes 2005)               │          │
│  │     • Progress to heavy slow resistance (HSR)      │          │
│  │                                                   │          │
│  │  3. ADJUNCTS                                       │          │
│  │     • Isometric exercises (pain modulation)        │          │
│  │     • Patellar strap (offloading)                  │          │
│  │     • Ice post-activity                            │          │
│  │     • Biomechanical optimization (hip/ankle)       │          │
│  └──────────────────────────────────────────────────┘          │
│                           ↓                                    │
│                   Review at 12 weeks                           │
│                           ↓                                    │
│              VISA-P improvement ≥13 points?                    │
│                           ↓                                    │
│           YES ↓                          NO ↓                  │
│                                                                │
│  ┌─────────────────────┐       ┌──────────────────────────┐   │
│  │  Continue protocol   │       │  SECOND-LINE: Adjunctive  │   │
│  │  Gradual return to   │       │  Therapies (3 months)     │   │
│  │  sport               │       ├──────────────────────────┤   │
│  └─────────────────────┘       │  1. ESWT (shockwave)      │   │
│                                │     • 3 sessions, 1/week   │   │
│                                │     • Focused or radial    │   │
│                                │                           │   │
│                                │  2. PRP Injection          │   │
│                                │     • Ultrasound-guided    │   │
│                                │     • 1-2 injections       │   │
│                                │     • Continue eccentric   │   │
│                                │                           │   │
│                                │  3. High-Volume Injection  │   │
│                                │     • Strips neovessels    │   │
│                                └──────────────────────────┘   │
│                                           ↓                   │
│                                   Review at 6 months          │
│                                           ↓                   │
│                              Still symptomatic?               │
│                                           ↓                   │
│                                         YES ↓                 │
│                                                               │
│  ┌──────────────────────────────────────────────────┐         │
│  │  THIRD-LINE: Surgical (Refractory > 6-12 months)  │         │
│  ├──────────────────────────────────────────────────┤         │
│  │  • Arthroscopic debridement                       │         │
│  │  • Open debridement ± excision degenerative tissue│         │
│  │  • Post-op: Eccentric loading protocol resumes    │         │
│  │  • RTP: 4-6 months                                │         │
│  └──────────────────────────────────────────────────┘         │
│                                                               │
│  ⚠️ CONTRAINDICATED AT ALL STAGES:                            │
│     • Corticosteroid injections (rupture risk)                │
│     • Complete rest > 2 weeks (tendon atrophy)                 │
│     • Premature return to sport                               │
│                                                               │
└────────────────────────────────────────────────────────────────┘

First-Line: Conservative Management

1. Load Management

Principle: Reduce tendon load to below the threshold that exceeds healing capacity, but avoid complete rest (which causes tendon weakening).

Guidelines:

• Blazina Stage 1-2: Continue sport with 50% volume reduction; monitor pain (should be ≤3/10 during activity, return to baseline within 24 hours)
• Blazina Stage 3: Cease jumping/running activities; maintain cardiovascular fitness (swimming, cycling)
• Return to sport: Gradual return only when pain-free with daily activities and VISA-P > 80

2. Eccentric Loading Exercises (GOLD STANDARD)

Evidence Base: Multiple RCTs demonstrate eccentric loading as the most effective conservative treatment, with 70-80% achieving significant improvement at 12 weeks. [6,7]

Decline Squat Protocol (Visnes and Bahr 2007): [7]

Equipment:

• 25° decline board (slant board)
• Weights (backpack or weighted vest for progression)

Technique:

1. Stand on affected leg on decline board (heel lower than forefoot)
2. Slowly lower into single-leg squat (3 seconds to 60° knee flexion)
3. Use opposite leg to return to starting position
4. Pain allowance: "Load-to-pain" approach—continue exercise even if mild pain (≤5/10), but reduce load if > 5/10

Dosage:

• 3 sets × 15 repetitions
• Twice daily (morning and evening)
• Every day for 12 weeks
• Progression: Add weight (backpack) when pain-free at baseline load; increase 2.5-5kg per week

Mechanism: Eccentric loading promotes collagen synthesis, increases tendon stiffness, reduces neovascularisation, and reorganizes tendon structure. [16]

3. Heavy Slow Resistance (HSR) Training

Alternative to decline squats, particularly for patients unable to tolerate high-volume eccentric training. [17]

Protocol (Kongsgaard 2009):

• Exercise: Leg press, hack squat (bilateral)
• Load: 15 RM (repetition maximum)
• Progression: Week 1-3 (4×15 RM), Week 4-6 (4×12 RM), Week 7-9 (4×10 RM), Week 10-12 (4×8 RM)
• Frequency: 3 times per week
• Duration: 12 weeks

Evidence: Comparable outcomes to eccentric training, may have better adherence. [17]

4. Isometric Exercises

Indication: Acute pain modulation (immediate pain reduction during flares).

Protocol:

• Single-leg leg extension (seated)
• Hold at 60° knee flexion
• Maximal voluntary contraction
• 5 holds × 45 seconds
• 2-minute rest between holds

Mechanism: Cortical pain inhibition, temporary analgesia; does NOT stimulate tendon remodeling (adjunct only). [18]

5. Adjunctive Measures

Second-Line: Interventional Therapies

Indications: Failed conservative management (≥3 months), persistent VISA-P less than 70

1. Extracorporeal Shockwave Therapy (ESWT)

Mechanism: Mechanical stimulation → neovascularisation disruption, substance P reduction, collagen remodeling. [8]

Protocol:

• Type: Focused or radial ESWT
• Dosage: 2000-3000 shocks per session, 0.1-0.3 mJ/mm²
• Frequency: 1 session per week × 3-4 weeks
• Concurrent: Continue eccentric loading

Evidence:

• Systematic review (van der Worp 2013): Moderate-quality evidence for benefit in chronic tendinopathy (> 3 months)
• Success rate: 60-70% improvement in pain and function at 6 months [8]
• NNT (number needed to treat): 4-5

Side Effects: Transient pain/redness (30%), bruising (10%)

2. Platelet-Rich Plasma (PRP) Injection

Mechanism: Growth factors (PDGF, TGF-β, VEGF) from platelets stimulate tendon healing (controversial—also increases inflammation). [9]

Technique:

• Ultrasound-guided injection into hypoechoic region
• Volume: 3-5mL leukocyte-poor PRP (LP-PRP preferred)
• Method: "Dry needling" + PRP (multiple tendon fenestrations)
• Post-injection: Relative rest 2 weeks, then resume eccentric protocol

Evidence:

• Mixed results: Some RCTs show benefit over placebo; others show no difference
• Meta-analysis (Andriolo 2019): Small benefit at 6-12 months (VISA-P improvement +10 points) [9]
• Optimal formulation unclear: LP-PRP vs. leukocyte-rich PRP debated

Side Effects: Pain (50%, resolves in 1 week), infection (less than 1%), tendon rupture (rare)

Cost: $500-1500 per injection (not typically covered by insurance)

3. High-Volume Injection (HVI)

Mechanism: Mechanical disruption of neovessels and associated sensory nerves using high-volume saline. [19]

Technique:

• Ultrasound-guided injection between patellar tendon and Hoffa fat pad (not intratendinous)
• Injectate: 50mL saline + 10mL 0.5% bupivacaine + 25mg hydrocortisone (single dose)
• Post-procedure: Eccentric loading after 1-week rest

Evidence:

• RCT (Morton 2015): Superior to corticosteroid injection alone; 70% pain reduction at 6 months [19]
• Mechanism debated: May be neovessel disruption or simply volume effect

4. Sclerotherapy (Polidocanol Injection)

Mechanism: Sclerosing agent targets neovessels (thought to carry sensory nerves).

Technique:

• Ultrasound-guided injection of 5mg/mL polidocanol into neovessels
• 2-3 injections at 6-week intervals

Evidence:

• Limited high-quality RCTs: Some early promise in Achilles tendinopathy; less studied in patellar tendinopathy
• Not widely adopted due to inconsistent results

Third-Line: Surgical Management

Indications:

• Failure of conservative management for 6-12 months
• VISA-P less than 50 despite structured rehabilitation
• Imaging showing extensive structural pathology
• Elite athlete requiring definitive treatment

Contraindications:

• Poor compliance with conservative treatment (likely poor surgical outcome)
• Active infection
• Unrealistic patient expectations

Surgical Techniques

Operative Findings:

• Hypertrophic, friable, discolored tendon tissue
• Neovascularisation visible
• Separation of collagen bundles
• Calcification (chronic cases)

Post-Operative Protocol:

• 0-2 weeks: Weight-bearing as tolerated, knee brace (comfort), ROM exercises
• 2-6 weeks: Progressive strengthening (eccentric protocol)
• 3 months: Light running (pain-free)
• 6 months: Full return to sport

Outcomes:

• Success rate: 60-90% good-to-excellent outcomes at 1-2 years [11]
• RTP: Average 6 months (range 3-12 months)
• Complications: Infection (2%), stiffness (5%), recurrence (10-20%)

What NOT to Do

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10. Complications

Of the Condition

Of Treatment

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11. Prognosis and Outcomes

Conservative Management

"Success" defined as: VISA-P improvement ≥20 points or final score ≥80

Surgical Management

• Good-to-excellent outcomes: 60-90% at 1-2 years [11]
• Return to sport: 70-85% (average 6 months)
• Pre-injury level: 50-60%

Prognostic Factors

Good Prognosis

• Short symptom duration (less than 6 months)
• Young age (less than 25 years)
• Localized inferior pole pathology
• High treatment compliance
• Early intervention

Poor Prognosis

• Long symptom duration (> 12 months)
• Extensive mid-substance pathology
• Previous corticosteroid injection
• Poor compliance with eccentric loading
• Bilateral symptoms
• High BMI

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12. Prevention Strategies

Primary Prevention

Target: Athletes in jumping sports

Secondary Prevention

Target: Athletes with early/Stage 1 symptoms

• Early eccentric loading protocol
• Load modification (reduce training volume by 30-50%)
• Monitor VISA-P (if decreasing, escalate intervention)

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13. Key Guidelines and Evidence

Guidelines

Landmark Studies

1. Visnes and Bahr (2007): RCT demonstrating efficacy of eccentric decline squats (70% success rate at 12 weeks) [7]
2. Kongsgaard et al. (2009): Heavy slow resistance training comparable to eccentric loading [17]
3. van Ark et al. (2016): Isometric exercises for in-season pain management [18]
4. Morton et al. (2015): High-volume injection superior to corticosteroid alone [19]
5. Cook and Purdam (2009): Tendon continuum model (reactive → dysrepair → degenerative) [16]

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14. Examination Focus

FRCS/MRCS Viva: Patellar Tendinopathy

Exam Detail: #### Station Scenario

"A 24-year-old semi-professional volleyball player presents with a 6-month history of anterior knee pain. Examination reveals focal tenderness at the inferior pole of the patella. Ultrasound shows a 4mm hypoechoic region within the proximal patellar tendon with increased Doppler signal. Discuss your management."

Model Answer Structure

1. Confirm Diagnosis

• "This is a classic presentation of patellar tendinopathy—previously called 'jumper's knee'—common in jumping athletes like volleyball players."
• "The key diagnostic features are the gradual onset, inferior pole tenderness, and ultrasound confirmation of tendinosis with neovascularisation."

2. Explain Pathophysiology

• "The pathology is degenerative (tendinosis), not inflammatory. Histology shows collagen disorganization, mucoid degeneration, and neovascularisation, but an absence of inflammatory cells."
• "It results from repetitive loading exceeding the tendon's healing capacity, leading to a failed healing response."

3. Initial Management

• "First-line management is conservative with eccentric loading exercises—specifically the decline squat protocol."
• "This involves single-leg squats on a 25-degree decline board, 3 sets of 15 repetitions, twice daily for 12 weeks. This has Level I evidence with 70-80% success rates."
• "I would also implement load management—reduce training volume by 50%, avoid jumping temporarily, and monitor symptoms using the VISA-P questionnaire."

4. Address Contraindications

• "Importantly, corticosteroid injections are absolutely contraindicated. They cause collagen necrosis, reduce tensile strength by 35-50%, and increase rupture risk 5-10 fold."

5. Second-Line Options

• "If conservative measures fail after 3-6 months, I would consider extracorporeal shockwave therapy (ESWT) or potentially a platelet-rich plasma (PRP) injection under ultrasound guidance."
• "ESWT has moderate-quality evidence with 60-70% success rates. PRP evidence is more mixed, with some studies showing benefit at 6-12 months."

6. Surgical Indications

• "Surgery is reserved for refractory cases failing 6-12 months of structured conservative treatment. Options include arthroscopic or open debridement of degenerative tissue."
• "Success rates are 60-90%, but return to sport takes 6 months on average, and only 50-60% return to pre-injury level."

7. Prognosis

• "Overall prognosis with conservative management is good—70-80% improve with eccentric loading. However, it's a slow process requiring patience and compliance. Elite athletes may face career-ending implications in 5-10% of cases."

Common Viva Questions and Answers

Q1: Why is it called 'tendinosis' rather than 'tendonitis'?

• "Histology shows no inflammatory cells—no neutrophils, macrophages, or lymphocytes. The pathology is degenerative with collagen disorganization and mucoid degeneration. The term 'tendinopathy' is now preferred as it's pathologically neutral."

Q2: What is the mechanism of action of eccentric loading?

• "Eccentric loading stimulates collagen synthesis, particularly Type I collagen. It increases tendon stiffness and load tolerance. It may also reduce neovascularisation and promote tendon remodeling. The exact mechanism is debated, but there's strong RCT evidence for efficacy." [Reference: Kongsgaard 2007, Cook 2009]

Q3: What is the VISA-P score?

• "The Victorian Institute of Sport Assessment - Patella is a validated 100-point questionnaire assessing pain and function. It's the gold standard outcome measure for patellar tendinopathy. A score of 100 is asymptomatic; less than 50 indicates severe symptoms. The minimal clinically important difference is 13 points."

Q4: What would you see on MRI?

• "On T2 or proton-density fat-saturated sequences, I'd expect increased signal within the tendon due to mucoid degeneration. There may be thickening of the tendon (> 6mm anteroposterior), peritendinous edema, and potentially bone marrow edema at the inferior patellar pole indicating enthesopathy."

Q5: When would you consider surgery?

• "I'd consider surgery for patients who have failed at least 6-12 months of structured conservative management—including eccentric loading, load modification, and potentially ESWT or PRP—who remain significantly symptomatic with VISA-P less than 50 and extensive structural pathology on imaging."

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15. Patient/Layperson Explanation

What is Jumper's Knee?

Jumper's knee is a painful condition affecting the tendon that connects your kneecap (patella) to your shinbone (tibia). This tendon, called the patellar tendon, helps you straighten your leg when you jump, run, or kick.

What Causes It?

The condition is caused by overuse—doing too much jumping, running, or squatting without giving your tendon enough time to recover. Over time, small tears develop in the tendon that don't fully heal, leading to pain and weakness.

It's most common in:

• Basketball and volleyball players (hence "jumper's knee")
• Runners
• Athletes who do a lot of jumping or sudden stops

What Are the Symptoms?

• Pain at the front of the knee, right below the kneecap
• Worse with jumping, landing, squatting, or going up/down stairs
• Stiffness after sitting for a long time (like at the movies)
• Gradual onset—it builds up over weeks or months

How is It Diagnosed?

Your doctor will:

• Ask about your activities and symptoms
• Examine your knee (there's usually a very tender spot just below the kneecap)
• Sometimes order an ultrasound or MRI to confirm the diagnosis and see how severe it is

How is It Treated?

Good news: Most people get better without surgery using exercises and rest modifications.

Main Treatment: Special Exercises (Eccentric Loading)

The most important treatment is a specific type of exercise called "decline squats":

• You stand on a slanted board and slowly lower yourself on one leg
• Do this twice a day for 12 weeks
• About 70-80% of people improve with this approach

It takes patience—tendons heal slowly, and you may need 3-6 months to fully recover.

Other Treatments

• Reduce jumping/high-impact activities temporarily (but don't stop moving completely)
• Ice after activities
• Patellar strap (a band worn below the kneecap to reduce stress)
• Physical therapy to strengthen your hip and leg muscles

If Exercises Don't Work

If you don't improve after 3-6 months, your doctor might suggest:

• Shockwave therapy: Sound waves stimulate healing
• Platelet-rich plasma (PRP) injection: Using your own blood to promote healing
• Surgery (rare): Only if nothing else works after 6-12 months

What to Avoid

⚠️ Important: Avoid cortisone (steroid) injections—they can weaken the tendon and increase the risk of it tearing completely.

Will It Get Better?

Yes, most people improve with treatment, but it requires:

• Consistency with exercises (every day for 12 weeks)
• Patience (healing is slow)
• Avoiding activities that make it worse until it's healed

About 70-80% of people get significantly better with exercises alone. Athletes can usually return to sport, but it may take 6-12 months to get back to full activity.

When to See a Doctor Urgently

Seek immediate medical attention if you:

• Hear a "pop" and suddenly can't straighten your knee (may be a tendon rupture)
• Have severe swelling, redness, or warmth (may be infection)

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16. References

Primary Resources

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18. van Ark M, Cook JL, Docking SI, et al. Do isometric and isotonic exercise programs reduce pain in athletes with patellar tendinopathy in-season? A randomised clinical trial. J Sci Med Sport. 2016;19(9):702-706. PMID: 26707957 DOI: 10.1016/j.jsams.2015.11.006

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