Patellar tendon tear

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Definition

A tear to the patellar tendon tear can be partial, with only some fibers torn, or a complete tear with total seperation between the patella and the tendon.



Clinically Relevant Anatomy

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Epidemiology /Etiology

 Injury

A patellar tendon rupture can be caused by a sudden contraction of the quadriceps against resistance.
When a strong force affects the knee, a tear can arise. This can happen when movements like jumping, falling,  weight lifting,… are performed. It’s most common that a tear arises when the knee is bent and the foot planted on the floor, f.e. when a basketball player lands of a jump. A tear can also arises by the great impact to the front of the knee by a fall.

 Surgery

There’s a higher risk for a tear when a previous major knee surgery  is done, like a total knee arthroplasty and an anterior cruciate ligament construction with central one third patellar tendon autograft.

 Tendon weakness

Caused by: 

- Patellar tendonitis  (http://www.physio-pedia.com/index.php/Patellar_Tendinitis)
- Chronic diseases like chronic renal failure, hyper betalipoproteinemia, rheumatoid arthritis (http://www.physio-pedia.com/index.php/Rheumatoid_Arthritis), systemic lupus erythmatosus (SLE) (http://www.physio-pedia.com/index.php/Systemic_Lupus_Erythematosus), diabetes mellitus (http://www.physio-pedia.com/index.php/Diabetes), infection.
- Steroid injections
- Tendon calcification
- Collagen disorders
- Fatty tendon degeneration
- Metabolic disorders

Characteristics/Clinical Presentation

The following symptoms are typical for someone with a patellar tendon tear:

- The patient is unable to continue activity 
- The patient can’t resume weightbearing or does so only with assistance 
- An indentation at the bottom of your kneecap where the tendon tore.
- Bruising
- Cramping
- Tenderness 
- A proximally displaced patella, because it’s no longer anchored to your shinbone 
- Incomplete extensor function 
- Walking will be difficult, due to the knee buckling or giving way
- Hemarthrosis

Sometimes people can feel a tearing or popping sensation, followed by pain and swelling.

When a tear is caused by a medical condition, like tendonitis, the tendon usually tears in the middle.

Differential Diagnosis

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Diagnostic Procedures

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Outcome Measures

Most patients undergoing early primary repair achieve nearly full return of knee motion and extension strength, although persistent quadriceps atrophy is common. Patients who underwent a delayed repair have greater persistent quadriceps atrophy.

A total recovery of a patellar tendon rupture takes about 6 months normally, but many patients reported that they required 12 months before reaching their goals.

Examination

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Medical Management

The treatment depends of the age, the activity level and the size of the tear of the patient.

Surgical repair reattaches the torn tendon to the kneecap. It’s better that the repair is performed early after the injury. An early repair, within 2 to 6 weeks, may prevent the tendon from scarring and tightening in a shortened position. In delayed diagnoses, more than 6 weeks after the rupture, quadriceps contracture and fibrous adhesions make the surgical repair and restoration of the patellar tendon length more complicated. Surgical repair is necessary to reestablish optimal extensor function.

Physical Therapy Management

Nonsurgical treatment of a patellar tendon tear

This kind of treatment takes place by patients with a small, partial tear.


Immobilization is important in this treatment. Incomplete lessions are treated with a cylindrical cast in extension for 6 weeks. This will keeps your knee straight to help it heal. Crutches are used to help you in avoiding putting all of your weight on your affected knee. As heeling progresses, the amount of flexion allowed by the brace may be increased. Exercises to strengthen the quadriceps muscles can be done. In addition straight leg raises can be executed. When the brace is unlocked, the patient can exercise with a higher range of motion and more strengthening exercises will be done to restore the strength and range of motion.

Postoperative rehabilitation of a patellar tendon tear

Classic rehabilitation involves the use of a cylinder cast for 6 weeks. The patient is allowed to bear weight as tolerated with crutches in the cast. Active flexion to 45° with passive extension may be started short after the operation, as well as isometric quadriceps and hamstring exercises. After 6 weeks the patient is converted to a control-dial hinged knee brace. The brace begins at 0 to 40 degrees and advanced to 10 degrees per week over the next 6 weeks. In this period, progressive quadriceps, hamstring strengthening and gait training are also performed. The brace is discontinued when the patient has adequate quadriceps function and 90 degrees of motion. Resistive strengthening and continued range-of-motion activities may be done after the brace is discontinued. When the patient has an adequate quadriceps control, isokinetic exercices and sport-specific functional rehabilitation may be started.    

Rehabilitation should focus on regaining range of motion and quadriceps control, followed by increasing muscle mass and sport-specific functions. 

It’s generally accepted that the knee should be immobilized in extension postoperatively for the tendon to heal without tension on the repair. Therefore, 6 weeks of immobilization in a cylinder cast was done routinely by many surgeons with generally good results.
More and more surgeons are starting passive knee motion immediately after surgery, controlled movements early after the repair. An early range of motion would reduce the risk of stiffness and the need for secondary manipulation.

The timeline for physical therapy and also the type of exercises will be individualized to the patient. It’s based on the type of tear, surgical repair, medical condition, and the specific needs of the patient. 

Resources

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Clinical Bottom Line

References

1. R. Wilkerson and S. J. Fischer, “Patellar Tendon Tear”, orthoinfo.aaos.org, February 2016. [Online]. https://orthoinfo.aaos.org/en/diseases--conditions/patellar-tendon-tear (Level of evidence: 5)


2.  Tommaso Bartalena, Maria Francesca Rinaldi, Patellar tendon rupture: radiologic and ultrasonographic findings, Western Journal of Emergency Medicine – jun 2009


3.  http://emedicine.medscape.com/article/1249472-overview#a0102


4. Jerome G. Enad, Patellar tendon ruptures, Southern medical journal – v92 n6 pg563-566 jun 1999


5.  Michael I. Greenberg, Greenberg's text-atlas of emergency medicine, pg 527

6.  Nicola Maffulli, Per Renström, Wayne B. Leadbetter, Tendon injuries: basic science and clinical medicine - pg172-175

 7. Peter T. Simonian, Brian J. Cole, Sports injuries of the knee: surgical approaches – pg175-181

 8. Giles R. Scuderi, Alfred J. Tria, The Knee: A Comprehensive Review - pg313-322