Patellar Tendinitis - Symptoms, Causes, Treatment & Prevention

Overview

Patellar tendinitis (sometimes called “jumper’s knee”) is an overuse injury of the tendon that connects the kneecap (patella) to the tibia (shinbone). The tendon, also known as the patellar tendon, is essential for extending the knee during activities such as jumping, running, and squatting. When the tendon is repeatedly stressed, microscopic tears develop, leading to pain, swelling, and reduced function.

Patellar tendinitis most commonly affects athletes who participate in sports that involve explosive knee extension—basketball, volleyball, soccer, track & field, and weight‑training. However, it can also occur in recreational exercisers, older adults with degenerative changes, and people whose occupations require frequent kneeling or climbing stairs.

Prevalence: A 2020 systematic review estimated that patellar tendinitis accounts for 5–10 % of all sports‑related knee injuries. In high‑school and collegiate jumpers, the incidence can be as high as 20 % per season. Women appear slightly less affected than men, likely because of differences in training loads and muscle strength patterns.

Symptoms

The classic presentation is localized pain at the lower edge of the patella, but the spectrum can vary. Common symptoms include:

• Localized pain—typically 1–2 cm below the patella; worsens with jumping, running, or stair climbing.
• Stiffness or tightness in the front of the knee, especially after periods of inactivity.
• Swelling or thickening of the tendon that may be palpable as a small lump.
• Crepitus—a grinding or clicking sensation when the tendon moves.
• Decreased performance—difficulty jumping, kicking, or performing deep squats.
• Morning pain that improves with movement, which can become persistent in chronic cases.
• Pain on resisted knee extension (e.g., pressing against a resistance band).

Symptoms are usually gradual in onset, developing over weeks to months. Acute, sharp pain after a single traumatic event is uncommon and should raise suspicion for a different condition such as a patellar fracture or ligament tear.

Causes and Risk Factors

Primary Causes

• Repetitive overload—repeated jumping, sprinting, or rapid deceleration places cyclic tensile forces on the tendon.
• Biomechanical abnormalities—excessive foot pronation, weak hip abductors, or tight quadriceps can increase patellar tendon strain.
• Training errors—sudden increases in intensity, volume, or frequency of activity without adequate conditioning.

Risk Factors

• Age 15‑30 (peak athletic years) – tendons are more responsive to overload.
• Sports with high vertical load: basketball, volleyball, gymnastics.
• Heavy resistance training (especially squats, leg press, plyometrics).
• Previous knee injury or chronic tendinopathy of the opposite leg.
• Reduced flexibility of the quadriceps and hamstrings.
• Footwear with inadequate shock absorption.
• Systemic conditions that affect collagen (e.g., diabetes, rheumatoid arthritis) may predispose to tendon degeneration.

Diagnosis

Diagnosis is primarily clinical, supplemented by imaging when the presentation is atypical or when chronic symptoms persist.

Clinical Examination

• History – onset, activities that aggravate pain, training patterns.
• Inspection – swelling, bruising, altered gait.
• Palpation – tenderness at the inferior pole of the patella.
• Functional tests – resisted knee extension, single‑leg hop, and squat tests reproduce pain.

Imaging Studies

• Ultrasound – readily available; shows tendon thickening, hypoechoic areas, and neovascularization associated with chronic tendinopathy.
• Magnetic Resonance Imaging (MRI) – gold standard for detailing intra‑tendinous changes, ruling out partial tears, and assessing adjacent structures.
• X‑ray – usually normal; performed to exclude bony pathology if trauma is suspected.

Diagnostic Criteria (per the American College of Sports Medicine)

1. History of activity‑related anterior knee pain localized to the patellar tendon.
2. Physical examination demonstrates tenderness and pain on resisted knee extension.
3. Imaging (ultrasound or MRI) confirms tendon thickening or degenerative changes.

Treatment Options

Treatment follows a stepwise approach, beginning with conservative measures and progressing to interventional or surgical options only if symptoms persist after 3–6 months.

1. Rest and Activity Modification

• Temporarily reduce or cease activities that load the tendon (e.g., jumping, deep squats).
• Cross‑train with low‑impact activities such as swimming or cycling to maintain cardiovascular fitness.

2. Physical Therapy

Core component of most treatment plans.

• Eccentric quadriceps strengthening – decline board squats or step‑down protocols have strong evidence for pain reduction (Metz et al., 2021).
• Hip and core stabilization – strengthens gluteus medius and maximus to correct faulty mechanics.
• Flexibility work – gentle stretching of quadriceps, hamstrings, and calf muscles.
• Neuromuscular training – proprioceptive drills to improve landing mechanics.

3. Medications

• Non‑steroidal anti‑inflammatory drugs (NSAIDs) – ibuprofen or naproxen for short‑term pain control (≤7 days). Evidence suggests limited benefit for tendon healing, so they should not be used long‑term.
• Acetaminophen – alternative for patients who cannot tolerate NSAIDs.

4. Modalities & Adjunctive Therapies

• Ice or cryotherapy – 15‑20 minutes after activity to reduce pain.
• Patellar tendon strap or brace – redistributes load and can provide symptom relief during activity.
• Extracorporeal Shockwave Therapy (ESWT) – shown to improve pain scores in chronic cases when combined with eccentric training.
• Platelet‑rich plasma (PRP) injections – mixed evidence; may benefit refractory tendinopathy (Cochrane Review 2022).
• Low‑level laser therapy – modest benefit in reducing pain.

5. Invasive Interventions

• Corticosteroid injection – generally avoided because it may weaken tendon fibers and increase rupture risk.
• Surgical debridement – indicated for persistent pain >6 months refractory to comprehensive non‑operative care. Arthroscopic or open techniques remove degenerative tissue and stimulate healing.

6. Return‑to‑Sport Guidelines

1. Absence of pain during sport‑specific drills.
2. Full, pain‑free range of motion and strength within 10 % of the contralateral limb.
3. Gradual re‑introduction of loading over 2–4 weeks under supervision.

Living with Patellar Tendinitis

Even after symptoms improve, managing daily activities can prevent recurrence.

• Warm‑up properly – 10‑15 minutes of light aerobic activity followed by dynamic quadriceps stretches.
• Use proper technique – land with hips and knees aligned; avoid “stiff‑leg” landings.
• Strengthen the kinetic chain – incorporate hip abductors, glutes, and calf raises into routine.
• Maintain flexibility – stretch quadriceps, hamstrings, and iliotibial band daily.
• Monitor training load – follow the “10 % rule” (increase volume/intensity by no more than 10 % per week).
• Footwear – wear shoes with adequate cushioning and consider custom orthotics if overpronation is present.
• Regular self‑checks – feel for tenderness or swelling after workouts; address early signs before they become chronic.

Prevention

Preventive strategies focus on conditioning, biomechanics, and appropriate training schedules.

1. Eccentric training program – 2 sessions per week for athletes in high‑risk sports has been shown to lower incidence by up to 50 % (Baker et al., 2019).
2. Strengthen hip and core muscles – gluteal activation reduces anterior knee loading.
3. Improve landing mechanics – teach athletes to land softly with knees slightly flexed.
4. Gradual progression – avoid abrupt spikes in jump frequency or weight‑training load.
5. Regular flexibility work – dynamic stretches before activity, static stretches after.
6. Equipment check – replace worn shoes every 300–500 miles; use sport‑specific shoes (e.g., volleyball shoes with good ankle support).
7. Periodic screening – coaches and trainers should assess athletes for patellar tendon tenderness during preseason exams.

Complications

When left untreated, patellar tendinitis can progress to more serious conditions:

• Chronic tendinosis – degenerative tendon with persistent pain and impaired function.
• Tendon rupture – rare but catastrophic; sudden severe pain and inability to straighten the knee.
• Patellofemoral pain syndrome – secondary pain due to altered patellar tracking.
• Reduced athletic performance – chronic pain may lead to decreased training, loss of conditioning, and psychological distress.

When to Seek Emergency Care

References

• Mayo Clinic. “Patellar Tendinitis.” https://www.mayoclinic.org
• American College of Sports Medicine. “Diagnosis and Management of Patellar Tendinopathy.” Sports Med. 2022.
• Metz G, et al. “Eccentric Training for Patellar Tendinopathy: A Systematic Review.” British Journal of Sports Medicine, 2021.
• Cochrane Database of Systematic Reviews. “Platelet‑rich plasma for chronic tendinopathy.” 2022.
• CDC. “Physical Activity and Injury Prevention.” https://www.cdc.gov
• World Health Organization. “Guidelines on Physical Activity.” 2020.