Patellar Height Ratios

Abstract

Three blinded observers on three separate occasions calculated four commonly employed patellar height ratios on the knees of 15 patients who had three lateral radiographs each. The observers used the same measurement instrument, a hand-held goniometer ruler, to determine the relative reliability of each patellar height ratio. The measurements by the three observers were examined, and the error and reliability of the four methods of measurement were tested statistically. Among the four methods of measuring patellar height that we studied, the Blackburne-Peel method most consistently reproduced the patellar height index. Interobserver measurement error averaged 0.06 for all ratios. Values greater than 0.06 represented real patellar height changes. The ratios were not significantly affected by the change of knee flexion angle from 30 degrees to 50 degrees. Side-to-side patellar height measurement differences averaged 0.16, which suggests that the healthy contralateral limb is not reliable as a control. Mild arthritic changes decreased variability of measurements by an average of 24% because small osteophytes better defined the articular margins of the patella.

Assessment of Patellar Height Measurement Methods From Digital Radiography

“…The impact of skeletal maturity has sometimes also been assessed. In many cases, these analyses have used radiographs on abnormal or diseases knees 15 , 17 , 19 , 20 , 21 , 22 . Even fewer studies have compared inter-observer concordance between the commonest methods for measuring patellar height in normal knees, i.e.…”

Evaluation of patella alta using MRI measurements in adolescents

“…[51314] These methods evaluate the patella height indirectly according to various tibial reference points. [15] Numerous studies have compared these measurement methods, and different authors have emphasised the various advantages of the different methods.…”

“…[15] Numerous studies have compared these measurement methods, and different authors have emphasised the various advantages of the different methods. [71011121314] Over time, taking other indices into consideration, modifications have been made to some of the indices themselves, such as for the Insall–Salvati index, which has been updated as the modified Insall–Salvati index.…”

Radiographic Assessment of the Opening Wedge Proximal Tibial Osteotomy

“…They also warned that measurements using the Blackburne and Peel and the Caton and Deschamps indices are also abnormal in cases of low pseudo-patella (18) , and thus should not be used in isolation to determine the retraction of the patellar tendon. Barnett et al (3) suggested that because these are indices that use a line traced out by the tibial plateau, they may lead to reduced accuracy 34 , 35 , 36 .…”