MANUAL MINORS
A patellar fracture is an injury that affects the kneecap, the bone at the front of the knee, which is essential for the function of the extensor mechanism. This type of fracture commonly occurs due to direct trauma, such as falls onto the knee or direct blows, or due to indirect forces, such as a sudden contraction of the quadriceps. Depending on the severity, patellar fractures can be stable or unstable, displaced or non-displaced, and even comminuted (fragmented).
Diagnosis
Clinical diagnosis includes severe pain at the front of the knee, swelling, tenderness to touch, and in many cases, an inability to extend the leg or lift the leg straight. The knee may show significant joint effusion.
The fracture is confirmed by X-rays (anteroposterior, lateral, and axial views) of the knee, which help assess the displacement of the bone fragments. In complex cases, a computed tomography (CT) scan may be useful.
Differential Diagnosis
Condition | Key Differentiation |
|---|---|
Patellar Tendon Injury | Difficulty extending the leg, without visible fracture on X-rays. |
Quadriceps Tendon Injury | Pain and difficulty with active extension, but no fracture. |
Patellar Dislocation | Lateral displacement of the patella, without bone fracture. |
Knee Contusion | Localised pain and swelling, but no visible fracture on imaging. |
Tibial Plateau Fracture | Affects the proximal tibia, with deeper pain in the knee. |
Emergency Management
In the emergency department, the initial management of patellar fractures includes:
Immobilisation: A knee splint or immobiliser is applied to prevent movement and relieve pain.
Analgesia: NSAIDs and, in some cases, opioids are administered to control pain.
Extension Evaluation: The patient’s ability to actively extend the knee is assessed. Inability to do so suggests a displaced fracture or injury to the extensor apparatus.
If the fracture is open or severely displaced, the patient is prepared for urgent surgical treatment.
Definitive Treatment
Treatment of patellar fractures depends on the type and degree of displacement:
Conservative Treatment
Non-displaced or minimally displaced fractures (less than 2 mm in the joint space) are managed conservatively with immobilisation in full extension for 4-6 weeks. Patients may perform isometric quadriceps exercises during this period to prevent muscle atrophy.
Progressive range-of-motion exercises are allowed once the fracture has begun to heal.
Surgical Treatment
Displaced fractures (more than 2 mm in the joint space or 3 mm between bone fragments) or comminuted fractures require surgical intervention to restore the extensor mechanism and joint congruency. Surgical approaches include:
Figure-of-Eight Wire Cerclage (Tension Band Technique): This is the most common technique for transverse fractures. It compresses the fragments and facilitates healing.
Screws and Cerclage: Used for more complex fractures or with significant displacement.
Partial or Total Patellectomy: In cases of severe comminuted fractures where the patella cannot be adequately reconstructed, partial or total removal may be necessary.
Rehabilitation
Rehabilitation is crucial after either conservative or surgical treatment. Initially, knee movement is restricted, with passive mobilisation and quadriceps strengthening exercises starting as soon as it is safe.
Return to full weight-bearing and physical activity depends on the type of fracture and its healing, but typically takes between 6 and 12 weeks.
Regular follow-up with X-rays is necessary to ensure proper bone healing and to detect complications such as post-traumatic osteoarthritis or joint stiffness.
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