Patella alta: Difference between revisions

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== Outcome Measures  ==
== Outcome Measures  ==


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Several methods are used to determine the presence of patella alta. Insall and Salvati were the first to describe a method of establishing patellar height on the basis of the ratio of the length of the patellar tendon to the diagonal length of the patella on lateral radiographs. Various techniques, including those by Blackburne and Peel, Caton et al., and de Carvalho et al., have since been developed in the attempt to classify patellar position. In the modified Insall-Salvati ratio, patellar bone length is replaced with patellar articular cartilage length. The Insall-Salvati index, however, is the most widely accepted method because of its lack of dependence on the degree of knee flexion and its established MRI criteria<ref>Syed A. Ali, Robert Helmer and Michael R. Terk; Patella Alta: Lack of Correlation Between Patellotrochlear Cartilage Congruence and Commonly Used Patellar Height Ratios; AJR November 2009 vol. 193 no. 5 1361-1366.</ref><ref>JEROLD E  et al; Patella Alta and Patella Infera, THEIR ETIOLOGICAL ROLE IN PATELLAR DISLOCATION, CHONDROMALACIA, AND APOPHYSITIS OF THE TIBIAL TUBERCLE; J Bone Joint Surg Am. 1975 Dec;57(8):1112-5</ref><br>The Insall-Salvati ratio is the ratio of the patella tendon length to the length of the patella. This can be measured on a lateral knee xray or sagittal MRI. Ideally the knee is 30 degrees flexed<ref>Insall J, Salvati E.; Patella position in the normal knee joint. Radiology 1971; 101:101–104
Blackburne JS, Peel TE. A new method of measuring patellar height. J Bone Joint Surg Br 1977; 59:241–242</ref><br>The Blackburne-Peel ratio is used to assess patellar height, and determine presence of patella alta. A lateral radiograph of the knee with 30 degrees of flexion is obtained, and a horizontal line at the level of the tibial plateaux is drawn. Perpendicular to this line vertically and a measurement (B) made of the distance between the horizontal line and the inferior aspect of the patellar articular surface. A second measurement (A) is made along the patellar articular surface.<ref>Syed A. Ali, Robert Helmer, Michael R. Terk; Patella Alta: Lack of Correlation Between Patellotrochlear Cartilage Congruence and Commonly Used Patellar Height Ratio; AJR November 2009 vol. 193 no. 5 1361-1366</ref><br>• A/B is a measure of patellar height<br> Normal value = ratio of 0.8. <br> Patella alta = ratio &gt;1.0<br><br>


== Examination  ==
== Examination  ==

Revision as of 18:21, 4 September 2012

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Search Strategy[edit | edit source]

The following databases have been used to find information about "Patella alta": Pubmed, Medscape, Google scholar, Pedro, Online database of the VUB
Words that have been used: Patella alta, Conservative treatment AND patella alta, Patella alta AND physical therapy, Patellar dislocation & Etiology

Definition/Description[edit | edit source]

Patella alta or high-riding patella refers to an abnormally high patella in relation to the femur. The patella sits high on the femur where the groove is very shallow. Here the sides of the femoral groove provide only a small barrier to keep the high-riding patella in place. A strong contraction of the quadriceps muscle can easily pull the patella over the edge and out of the groove, leading to a patellar dislocation. This condition has been associated clinically with patellofemoral dysfunction and is considered a predisposing factor for the development of patellofemoral pain (PFP). Patella alta is also characterized as instability of the Patella[1][2][3] 

Clinically Relevant Anatomy[edit | edit source]

Patella_alta:_Clinically_relevant_anatomy

Etiology[edit | edit source]

Patella Alta can occur as the result of a sports injury, though the large majority of the time it is a congenital/developmental condition that is unrelated to trauma. Its pathophysiology is not completely clear, but it is hypothesized that one of the causes of Patella Alta, are abnormally long patellar tendons (>52 mm)[4][5] 

Characteristics/Clinical Presentation[edit | edit source]

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Differential Diagnosis[edit | edit source]

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Diagnostic Procedures[edit | edit source]

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Outcome Measures[edit | edit source]

Several methods are used to determine the presence of patella alta. Insall and Salvati were the first to describe a method of establishing patellar height on the basis of the ratio of the length of the patellar tendon to the diagonal length of the patella on lateral radiographs. Various techniques, including those by Blackburne and Peel, Caton et al., and de Carvalho et al., have since been developed in the attempt to classify patellar position. In the modified Insall-Salvati ratio, patellar bone length is replaced with patellar articular cartilage length. The Insall-Salvati index, however, is the most widely accepted method because of its lack of dependence on the degree of knee flexion and its established MRI criteria[6][7]
The Insall-Salvati ratio is the ratio of the patella tendon length to the length of the patella. This can be measured on a lateral knee xray or sagittal MRI. Ideally the knee is 30 degrees flexed[8]
The Blackburne-Peel ratio is used to assess patellar height, and determine presence of patella alta. A lateral radiograph of the knee with 30 degrees of flexion is obtained, and a horizontal line at the level of the tibial plateaux is drawn. Perpendicular to this line vertically and a measurement (B) made of the distance between the horizontal line and the inferior aspect of the patellar articular surface. A second measurement (A) is made along the patellar articular surface.[9]
• A/B is a measure of patellar height
 Normal value = ratio of 0.8.
 Patella alta = ratio >1.0

Examination[edit | edit source]

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Medical Management
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Physical Therapy Management
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Key Research[edit | edit source]

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Resources
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Clinical Bottom Line[edit | edit source]

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Recent Related Research (from Pubmed)[edit | edit source]

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References[edit | edit source]

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  1. ↑ Ward SR, Powers CM; The influence of patella alta on patellofemoral joint stress during normal and fast walking; Clin Biomech (Bristol, Avon). 2004 Dec;19(10):1040-7
  2. ↑ Stefanik JJ et al ; Quadriceps Weakness, Patella Alta, and Structural Features of Patellofemoral Osteoarthritis; Arthritis Care Res (Hoboken). 2011 Oct;63(10):1391-7
  3. ↑ Syed A. Ali, Robert Helmer, Michael R. Terk; Patella Alta: Lack of Correlation Between Patellotrochlear Cartilage Congruence and Commonly Used Patellar Height Ratio; AJR November 2009 vol. 193 no. 5 1361-1366
  4. ↑ Ward SR, Powers CM. The influence of patella alta on patellofemoral joint stress during normal and fast walking. Clin Biomech (Bristol, Avon). 2004;19:1040-7
  5. ↑ Ward SR, Terk MR, Powers CM.; Patella alta: association with patellofemoral alignment and changes in contact area during weight-bearing.; J Bone Joint Surg Am. 2007
  6. ↑ Syed A. Ali, Robert Helmer and Michael R. Terk; Patella Alta: Lack of Correlation Between Patellotrochlear Cartilage Congruence and Commonly Used Patellar Height Ratios; AJR November 2009 vol. 193 no. 5 1361-1366.
  7. ↑ JEROLD E et al; Patella Alta and Patella Infera, THEIR ETIOLOGICAL ROLE IN PATELLAR DISLOCATION, CHONDROMALACIA, AND APOPHYSITIS OF THE TIBIAL TUBERCLE; J Bone Joint Surg Am. 1975 Dec;57(8):1112-5
  8. ↑ Insall J, Salvati E.; Patella position in the normal knee joint. Radiology 1971; 101:101–104 Blackburne JS, Peel TE. A new method of measuring patellar height. J Bone Joint Surg Br 1977; 59:241–242
  9. ↑ Syed A. Ali, Robert Helmer, Michael R. Terk; Patella Alta: Lack of Correlation Between Patellotrochlear Cartilage Congruence and Commonly Used Patellar Height Ratio; AJR November 2009 vol. 193 no. 5 1361-1366


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