Skeletal Radiology

, Volume 33, Issue 8, pp 445–450 | Cite as

MRI criteria for patella alta and baja

  • Nogah Shabshin
  • Mark E Schweitzer
  • William B Morrison
  • Laurence Parker
Scientific Article



To determine the range of the patellar tendon length to patellar length ratio on magnetic resonance imaging (MRI) of the knee in order to aid in the establishment of MRI criteria for patella alta and baja.


Two hundred and forty-five patients ages 6–85 (mean 44) years who went through 262 consecutive 1.5 MRI studies of the knee performed during November 2000 through February 2001 were evaluated, regardless of their clinical symptoms.


Patellar length (PL) and patellar tendon length (TL) were measured by a single musculoskeletal radiologist on sagittal images by a line connecting the superior and inferior patellar poles and the shortest length of the inner margin of the tendon respectively. TL/PL ratio was subsequently calculated. The distribution of ratios was evaluated; the extreme 2.5% at each end of the distribution was defined as patella alta and baja.


The TL/PL ratio ranged between 0.56 and 1.71 (mean 1.05). After plotting the ratios, we noted an asymmetric curve skewed to the left. Based upon calculation of the extreme 2.5% of the ratio at each end of the plot, we determined that the MRI definition of patella alta and baja is a ratio of TL/PL of more than 1.50 and less than 0.74 respectively. We found that females had significantly higher TL/PL ratio than males (1.0878 and 1.0032 respectively). Ratios defined for patella alta and baja were 1.52 and 0.79 respectively in females and 1.32 and 0.74 respectively in males (p<0.0001).


Patella alta and baja are determined as TL/PL of more than 1.50 and less than 0.74 respectively, somewhat different than traditionally quoted radiographic and previously described MRI criteria.


Patella Magnetic resonance imaging (MRI) Knee 


  1. 1.
    Grelsamer RP, Meadows S. The modified Insall–Salvati ratio for assessment of patellar height. Clin Orthop 1992; 282:170–176PubMedGoogle Scholar
  2. 2.
    Miller TT, Staron RB, Feldman F. Patellar height on sagittal MR imaging of the knee. AJR 1996; 167:339–341PubMedGoogle Scholar
  3. 3.
    Grana WA, Krieghauser LA. Scientific basis of extensor mechanism disorders. Clin Sports Med 1985; 4:247–257PubMedGoogle Scholar
  4. 4.
    Insall J, Salvati E. Patella position in the normal knee joint. Radiology 1971; 101:101–104PubMedGoogle Scholar
  5. 5.
    Kannus PA. Long patellar tendon: Radiographic sign of patellofemoral pain syndrome. Radiology 1992; 185:859–863PubMedGoogle Scholar
  6. 6.
    Von Gumppenberg S, Jacob RP, Engelhardt P. Does Osgood-Schlatter disease modify the position of the patella? Z Orthop Inhre Brenzgeb 1984; 122:798–802Google Scholar
  7. 7.
    Aparicio G, Abril JC, Calvo E, Alvarez L. Radiographic study of patellar height in Osgood-Schlatter disease. J Pediatr Orthop 1997;17:63–66CrossRefPubMedGoogle Scholar
  8. 8.
    Tria AJ JR, Alicea JA, Cody RP. Patella baja in anterior crutiate ligament reconstruction of the knee. Clin Orthop 1994; 299:229–234PubMedGoogle Scholar
  9. 9.
    Noyes FR, Wojtys EM, Marshall MT. The early diagnosis and treatment of developmental patella infera syndrome. Clin Orthop 1991; 265:241–252PubMedGoogle Scholar
  10. 10.
    Mann FA, Wilson AJ, Gilula LA. Radiographic evaluation of the wrist: What does the surgeon want to know? Radiology 1992; 184:15–24PubMedGoogle Scholar
  11. 11.
    Sackett DL, Haynes RB, Tugwell P. Clinical epidemiology, a basic science for clinical medicine. Boston/Toronto: Little, Brown 1985: 51–55Google Scholar
  12. 12.
    Boot-Itt SB. The normal position of the patella. AJR 1930; 24:389–394Google Scholar
  13. 13.
    Blumensaat C. Die lageabweichungen und verrenkungen der kniescheibe. Ergebn Chir Orthop 1938; 31:149–223Google Scholar
  14. 14.
    Blackburne JS, Peel TE. A new method of measuring patellar height. J Bone Joint Surg 1977; 59:241–242Google Scholar
  15. 15.
    de Carvalho A, Andersen AH, Topp S, Jurick AG. A method for assessing the height of the patella. Int Orthop 1985; 9:195–197PubMedGoogle Scholar
  16. 16.
    Caton J, Deschamps G, Chambat P, Lerat JL, Dejour H. Les rotules basses-a propos de 128 observations. Riv Chir Orthop 1982; 68:317–325Google Scholar
  17. 17.
    Norman O, Egund N, Ekelund L, Runow A. The vertical position of the normal patella. Acta Orthop Scand 1983; 54:908–913PubMedGoogle Scholar
  18. 18.
    Linclau L. Measuring patellar height. Acta Orthop Belg 1984; 50:70–74PubMedGoogle Scholar
  19. 19.
    Ficat RP, Hungerford DS. Disorders of the patello-femoral joint. Baltimore: Williams and Wilkins, 1977Google Scholar
  20. 20.
    Iwano T, Kurosawa H, Tokuyama H, et al. Roentgenographic and clinical findings of patellofemoral osteoarthritis. Clin Orthop 1990; 252:190PubMedGoogle Scholar

Copyright information

© ISS 2004

Authors and Affiliations

  • Nogah Shabshin
    • 1
    • 2
  • Mark E Schweitzer
    • 3
  • William B Morrison
    • 2
  • Laurence Parker
    • 2
  1. 1.Department of Diagnostic ImagingChaim Sheba Medical CenterTel-HashomerIsrael
  2. 2.Department of RadiologyThomas Jefferson Medical CollegePhiladelphiaUSA
  3. 3.Department of RadiologyNew York University/Hospital for Joint DiseaseNew YorkUSA

Personalised recommendations