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Patellar Fracture

Written by Tele Demetrious

Updated:

(Also known as Fractured Patella, Fractured Knee Cap)

What is a patellar fracture?

A patellar fracture is a condition characterized by a break in the knee cap bone (patella) (figure 1).

Relevant Anatomy for a Patellar Fracture
Figure 1 – Relevant Anatomy for a Patellar Fracture

The knee comprises of the union of 3 bones – the long bone of the thigh (femur), the shin bone (tibia) and the knee cap (patella) (figure 1). The patella (knee cap) is situated at the front of the knee and lies within the tendon of the quadriceps muscle (the muscle at the front of the thigh). The quadriceps tendon envelops the patella and attaches to the top end of the tibia (figure 1). Due to this relationship, the knee cap sits in front of the femur forming a joint in which the bones are almost in contact with each other.

During certain activities, such as a fall onto the knee cap or following a direct blow to the front of the knee, stress is placed on the patella bone. When this stress is traumatic, and beyond what the bone can withstand, a break in the patella may occur. This condition is known as a patellar fracture.

Because of the large forces required to break the patella bone, a patellar fracture often occurs in combination with other injuries such as patellofemoral joint damage or a quadriceps tear.

Patellar fractures can vary in location, severity and type including stress fracture, displaced fracture, un-displaced fracture, compound fracture, greenstick, comminuted etc.

Causes of a patellar fracture

A patellar fracture most commonly occurs due to direct trauma to the knee cap such as a fall onto the knee cap or a direct blow to the patella (e.g. from a hockey stick). Occasionally it may also occur due to a forceful quadriceps contraction such as landing from a height. A stress fracture to the patella, although rare, may occur as a result of overuse, often associated with a recent increase or high volume of jumping. An acute patellar dislocation can also sometimes result in a fracture to the patella.

Signs and symptoms of a patellar fracture

Patients with this condition typically experience a sudden onset of sharp, intense pain at the front of the knee at the time of injury. This often causes the patient to limp so as to protect the patella. In severe cases, particularly involving a displaced fracture of the patella, weight bearing may be impossible. Pain is usually felt on the front or sides of the patella and can occasionally settle quickly with rest leaving patients with an ache at the site of injury that may be particularly prominent at night or first thing in the morning. Occasionally patients may experience symptoms in the back of the knee, the thigh or lower leg regions.

Patients with a patellar fracture may also experience swelling, bruising and pain on firmly touching the affected region of bone. Pain may also increase during certain movements of the knee when standing or walking (particularly up or down hills or on uneven surfaces) or when attempting to stand or walk. Squatting or kneeling is also usually painful with many patients being unable to perform these activities. In severe cases (with bony displacement), an obvious deformity may be noticeable. Occasionally patients may also experience pins and needles or numbness in the knee, lower leg, foot or ankle.

Diagnosis of a patellar fracture

A thorough subjective and objective examination from a physiotherapist is essential to assist with diagnosis of a patellar fracture. X-rays (including a skyline view of the patella) are usually required to confirm diagnosis and assess the severity of the fracture. Further investigations such as an MRI, CT scan or bone scan may be required, in some cases, to assist with diagnosis and assess the severity of the injury.

Treatment for a patellar fracture

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Prognosis of a patellar fracture

Patients with this condition usually make a full recovery with appropriate management (whether surgical or conservative). Return to activity or sport can usually take place in a number of weeks to many months and should be guided by the treating physiotherapist and specialist. In patients with severe injuries such as those that involve damage to other bones, soft tissue, nerves or blood vessels, recovery time may be significantly prolonged and there may be some ongoing disability.

Sometimes a poorly rehabilitated patellar fracture may develop into other conditions such as patellofemoral pain syndrome even though full bony healing may have taken place. In these instances further physiotherapy treatment and rehabilitation may be required before the patient is able to return to full activity, pain free.

Physiotherapy for a patellar fracture

Physiotherapy treatment is vital in all patients with this condition to hasten healing and ensure an optimal outcome. Treatment may comprise:

Other intervention for a patellar fracture

Despite appropriate physiotherapy management, some patients with this condition do not improve adequately and may require other intervention. The treating physiotherapist or doctor can advise on the best course of management when this is the case. This may include further investigations such as X-rays, CT scan, MRI or bone scan, periods of splinting or plaster cast immobilization or referral to appropriate medical authorities who can advise on any intervention that may be appropriate to improve the fractured patella. Occasionally, patients with fractures that are initially managed without surgical intervention may require surgery to stabilize the fracture and a bone graft to aid fracture healing.

Exercises for a patellar fracture

The following exercises are commonly prescribed to patients with a patellar fracture following confirmation that the fracture has healed or that pain free mobilization can commence as directed by the surgeon. You should discuss the suitability of these exercises with your physiotherapist prior to beginning them. Generally, they should be performed 3 times daily and only provided they do not cause or increase symptoms.

Your physiotherapist can advise when it is appropriate to begin the initial exercises and eventually progress to the intermediate, advanced and other exercises. As a general rule, addition of exercises should take place provided there is no increase in symptoms.

Initial Exercises

Static Quadriceps Contraction

Tighten the muscle at the front of your thigh (quadriceps) by pushing your knee down into a towel (figure 2). Put your fingers on your inner quadriceps to feel the muscle tighten during contraction. Hold for 5 seconds and repeat 10 times as hard as possible without increasing your symptoms.

Exercises for a Patellar Fracture - Static Quadriceps Contraction (left leg)
Figure 2 – Static Quadriceps Contraction (left leg)

Knee Bend to Straighten

Bend and straighten your knee as far as you can go without pain and provided you feel no more than a mild to moderate stretch (figure 3). Gradually increase movement as tolerated over a number of sessions provided the exercise is pain free. Repeat 10 – 20 times provided there is no increase in symptoms.

Exercises for a Patellar Fracture - Knee Bend to Straighten (right leg)
Figure 3 – Knee Bend to Straighten (right leg)

Hip Extension in Standing

Begin this exercise standing at a table or bench for balance. Keeping your back and knee straight, slowly take your leg backwards, tightening your bottom muscles (gluteals) (figure 4). Hold for 2 seconds then slowly return to the starting position. Repeat 10 times provided the exercise is pain free.

Exercises for a Patellar Fracture - Hip Extension in Standing (right leg)
Figure 4 – Hip Extension in Standing (right leg)

Intermediate Exercises

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Advanced Exercises

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Other Exercises

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Rehabilitation protocol for patellar fracture

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Some of the most commonly recommended products by physiotherapists to hasten healing and speed recovery in patients with this condition include:

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