Rupture of the patellar tendon (patellar tendon rupture)

Anatomy: The extensor system of the knee

The extensor system of the knee consists of the quadriceps muscle, the patella and the patellar tendon. When the quadriceps contracts, the patella is used as a "deflection pulley", the force is transferred to the tibial tuberosity via the patellar tendon and the knee is extended. The patellar tendon is a strong band of collagen fibers; It typically tears at the lower pole of the patella (proximal), more rarely in the middle or at the base of the tibia (distal). An intact tendon is essential for walking, climbing stairs, getting up and doing sports.

• Origin: Lower pole of the patella
• Insertion: Tuberositas tibiae (shinbone tuberosity)
• Function: Transmission of quadriceps strength for knee extension
• Neighboring structures: retinacula, Hoffa fat body, anterior capsule

Causes and risk factors

A patellar tendon rupture often results from a sudden, high pull on the tendon while the knee is bent - for example when landing after a jump or during an explosive start. Pre-existing structural changes in the tendon (tendinopathy) increase the risk. General factors can also affect tendon quality.

• Acute trauma: landing from a jump, abrupt braking, direct contusion
• Previous damage: patellar tendinopathy (jumpers knee), chronic tendinopathy
• Systemic factors: diabetes mellitus, chronic renal failure, rheumatic diseases
• Medication: Corticosteroid injections in/near the tendon, rarely fluoroquinolone antibiotics
• Previous surgeries/scarring: Previous patella or tendon surgery

Symptoms and warning signs

The symptoms usually begin suddenly. The decisive factor is whether active stretching is still possible. If the rupture is complete, stretching against gravity is usually no longer possible.

• Acute, stabbing pain below the kneecap
• Popping/cracking sensation at the moment of injury
• Rapid swelling and bruising (front knee)
• Palpable dent under the lower pole of the patella
• Patella appears “too high” (patella alta) when compared from side to side
• Inability to raise the extended leg (straight leg raise) in the event of a complete rupture
• Unsteady when walking, climbing stairs is hardly possible

First aid if a patellar tendon rupture is suspected

• Rest and immobilization: immobilize the knee in an extended position (e.g. splint), do not bend it forcefully
• Cooling: 10-15 minutes with a cloth in between, several times a day
• Elevation: Reduce swelling
• Reduce strain: Use forearm crutches if possible
• Analgesics: Short term e.g. B. paracetamol/ibuprofen as tolerated; Pay attention to interactions
• Get a medical check-up quickly: If you lose active extension, get an emergency check-up

Diagnostics in our practice

Diagnostics combines anamnesis, clinical examination and imaging procedures. The aim is to reliably record the degree of rupture (partial vs. complete tear), the location and accompanying injuries in order to plan further action in a well-founded manner.

• Anamnesis: mechanism of accident, previous damage/tendon pain, medications, previous illnesses
• Examination: Visible patella alta, palpable defect zone, hematoma; Test of active extension and straight leg raise
• Sonography: Dynamic assessment of tendon continuity, hematoma, rupture progression
• Lateral x-ray: patella height (patella alta), rule out bony avulsions
• MRI (if the findings/planning are unclear): exact location of the rupture, partial tears, quality of the tendon tissue, accompanying injuries

If there is an urgent suspicion, we will organize prompt imaging in Hamburg and discuss the results with you in an understandable manner. The choice between conservative and surgical approach is always individual and guideline-oriented.

Classification: partial tear vs. complete tear, acute vs. chronic

• Degree of rupture: partial rupture (part of the fibers intact) vs. complete rupture (no continuity, extension deficit)
• Location: At the lower pole of the patella (common), in the middle third of the tendon (less often), at the base of the tibia
• Timing: Acute (< 2-3 weeks) vs. chronic (retraction, scarring) – influences surgical method

Conservative treatment (for suitable partial tears)

Conservative therapy can be considered for stable partial tears without a relevant extension deficit. The prerequisite is that the tendon continuity is sufficiently preserved and the patella is in a normal position. The procedure is closely monitored to rule out secondary deterioration.

• Immobilization: stretching splint/orthosis, initial 0°–20° range of motion, gradual expansion
• Loading: Partial to full weight bearing depending on pain and stability, initially in an orthosis
• Physiotherapy: Early functional recruitment of the quadriceps (isometric), mobility maintenance, gait training
• Swelling management: lymphatic drainage, cooling, elevation
• Medication: Pain and inflammation management individually
• Regenerative options: PRP can be considered for selected partial cracks; Evidence mixed, careful indication and education required

Duration: Often 6-10 weeks until it is suitable for everyday use, sporting stress only after structural healing has progressed and strength has been built up. Close follow-up (clinical/sonographic) is essential.

Surgical treatment (standard for complete rupture)

If the patellar tendon is completely ruptured, surgery is usually the treatment of choice, especially for recent injuries. The aim is to anatomically restore tendon continuity and patella height in order to secure the extensor function.

• Timing of operation: As soon as possible (ideally within the first 1-2 weeks) to avoid retraction
• Techniques: Transosseous sutures through the patella or suture anchors at the lower pole of the patella; If necessary, cerclage or band augmentation
• Special situations: In the case of poor tissue quality or chronic ruptures, additional reinforcement (e.g. semitendinosus autograft)
• Anesthesia and setting: regional or general anesthesia; usually on a short-term basis
• Risk explanation: infection, secondary bleeding, thrombosis, stiffness, re-rupture, persistent pain

As a conservative practice, we advise you independently, carefully determine the indication for surgery and, if necessary, coordinate surgical care with experienced partners in Hamburg. We closely monitor aftercare and rehabilitation.

Follow-up treatment and rehabilitation

Follow-up treatment depends on the type of rupture and therapy. Structured, phase-based rehabilitation is crucial for a good functional outcome. Individualization takes place according to the healing process and medical control.

• Ability to work: Office work often after 2-4 weeks; physical work later (8-12+ weeks) depending on the load
• Sport: Gradually from 4-6 months at the earliest; Pivot/contact sports possibly 6-9 months
• Thrombosis prophylaxis: According to risk indications, coordinated by a doctor

Course and prognosis

With prompt, adequate treatment, the results are good overall. What is crucial is the early start of therapy, the restoration of the patellar height and consistent rehabilitation. Delayed or incomplete care can lead to permanent extension deficits, reduced strength or anterior knee pain.

• Good everyday function is achievable in most cases
• A return to competitive sport is possible, but requires patience and structured training
• Risk factors for delays: Chronic rupture, pronounced tendinopathy, systemic diseases

Possible complications and warnings

• Re-rupture or partial insufficiency of the tendon
• Patella alta/baja with altered biomechanics
• Restricted movement (especially flexion deficit) or extension deficit
• Front knee pain, cicatricial adhesions
• Infection, hematoma, thrombosis/embolism
• Complex regional pain syndrome (rare)

Immediate medical clarification is necessary if there is increasing swelling, redness/fever, new numbness, massive escalation of pain or shortness of breath/leg swelling (signs of thrombosis/embolism).

Prevention and long-term care

• Progressive training structure with sufficient regeneration times
• Correction of jumping and landing mechanics, core and hip stability
• Treat patellar tendon pain early (tendinopathy program)
• Avoid cortisone injections into the tendon
• Review of systemic risk factors (e.g. blood sugar, medications)

Special situations: children, elderly, differential diagnoses

True patellar tendon ruptures are rare in children and adolescents; Bony avulsions or so-called “sleeve” fractures at the lower pole of the patella occur more frequently. Tears of the quadriceps tendon (above the patella) are more common in older age - the symptoms (loss of stretch) are similar, the therapy is different. The differential diagnosis includes acute patellar luxation, patellar fracture, pronounced tendinopathy and bruises.

When should you go to the practice or emergency room?

• Immediate emergency clarification: No active stretching possible, palpable dent, raised patella
• Urgent evaluation within 24-48 hours: Persistent pain/swelling after trauma, unsteadiness when walking
• In the case of risk factors (diabetes, steroids) and an acute event, medical examination should be carried out early

We offer a timely assessment in our practice in Hamburg. If there is an urgent suspicion, we will immediately organize the necessary diagnostics and – if necessary – further surgical treatment.