27 male basketball player present to the ED, with a chief complaint of pain to L knee.
Patient states was playing basketball when his knee sudden gave way, then became swollen and difficult to walk.
The patients reports a 6 month history of tendon inflammation to his knee, which he has been receiving steroid injections from his general practitioner for.
On examination the knee moderately swollen compared to the other, with decreased flexion and extension, you send the patient of for an X-ray and think about what the diagnosis is.
Patellar Tendon Rupture:
- The rupture of the patellar tendon is uncommon, and often occurs in long-standing patellar tendon irritation.
- It usually occurs spontaneously or with minimal trauma, and has a higher predisposition in patients under 40.
- It is the third most common injury to the extensor mechanism of knee, following patellar fracture and quadriceps tendon rupture.
Risk Factors for Patellar Tendon Rupture
- Metabolic and inflammatory conditions
- Renal Failure
- Rheumatoid Arthritis
- Systemic Lupus Erythematous
- Steroid use and chronic intra-articular steroid injections
Anatomy and Physiology of Patellar Tendon Rupture:
- The patellar tendon attaches to the tibial tubercle on the front of the tibia just below the from of the knee, and is connected to the bottom of the patellar, above which are attached to the quadriceps tendon, followed by the quadriceps muscle.
- The patellar tendon allows the knee to flex and extend, allowing use of basic functions such as walking, running ect.
- Rupture of the patellar tendon usually occurs at the osseotendinous junction and causes complete derangement of the knee extensor mechanism.
Assessment of Patellar Tendon Rupture:
History, physical examination and plain radiographs are generally all that is required for diagnosis.
- Patients generally reports immediate and sudden onset of severe pain post injury
- May also report a popping or tearing sensation
- Swelling over the knee, and difficulty or inability to weight bear will also be reported
- Diffuse swelling to the anterior knee
- Ecchymosis (bruising)
- Patella Alta (abnormally high patellar in relation to femur)
- Tenderness exists along the anterior knee and retinacula, and a defect at level of rupture is usually palpable.
- Plain radiographs should be obtained (AP, lateral, and axial)
- Contralateral films can be obtained to measure patellar height
- The lateral view provides most information on tendon rupture, it should demonstrate patellar alta, but may also show calcification indicative of chronic patellar tendinosis.
- Axial view may demonstrate preexisting patellofemoral arthritis
- Ultrasound can be used to diagnose patellar tendon rupture easily, quickly, and cost effectively.
- The patellar tendon is imaged with longitudinal scans using high-frequency linear transducers.
- It normally appears as a continuous well-defined hyperechoic fibrillar structure bridging the patellar and the tibial tuberosity, while tears appear as hypoechoic areas of interruption of the fibrillar pattern.
- If plain radiographs and ultrasound don’t demonstrate patellar tendon rupture, but clinical suspicion still high MRI will provide a more definitive test and answer for tendon rupture.
Management of Patellar Tendon Rupture:
Emergency department management:
- Provide analgesia
- Ice to help relive swelling, apply every 2-3 hours for 20mins for first 24-48hours
- Compression/splint for support and stability
- Elevation to help reduce swelling
- Refer to orthopaedic surgeons for follow up and definitive management
Medical Vs Surgical Treatment:
- Medical treatment has a limited role in managing patellar tendon rupture, it generally increases the time to healing, patient needs to be in a splint or brace for 6-8 weeks and strengthening exercise are delayed for up 3 months post injury.
- Early surgical intervention for complete tears allows for best functional outcome for injured structures within the extensor mechanism.
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Lu, M. Johar, S. Veenema, K. & Goldblatt, J. (2009). Patellar Tendon Rupture with underlying Systemic Lupus Erythematous: A case Report. The Journal of Emergency Medicine. Published Ahead of Print. PMID: 19959318
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