title: The effect of quadriceps contraction during weight-bearing on four patellar height indices.
abstract: The effect of weight-bearing on the height of the patellar using four radiological indices was studied in 25 healthy men using lateral radiographs of the knee in 30 degrees of flexion non-weight-bearing and weight-bearing. The position of the patella was quantified using the Insall-Salvati, the modified Insall-Salvati, the Blackburne-Peel and the Caton indices. The contraction of the quadriceps on weight-bearing resulted in statistically significant proximal displacement of the patella with all four indices studied. The mean Insall-Salvati index was 0.919 (SD 0.063) before and 1.109 (SD 0.042) after weight-bearing (p = 0.001), while the mean modified Insall-Salvati index was 0.734 (SD 0.039) before and 0.896 (SD 0.029) after weight-bearing (p = 0.041). Similarly, the Blackburne-Peel index was 0.691 (SD 0.09) before and 0.807 (SD 0.137) after weight-bearing (p = 0.012). The mean Caton index was 0.861 (SD 0.09) before and 0.976 (SD 0.144) after weight-bearing (p = 0.023). The effect of quadriceps contraction should be considered in clinical studies where the patellar position indices are reported.
authors.affiliation: Centre for Arthroscopic and Shoulder Surgery, IASO General Hospital, Athens, Greece. cky@ath.forthnet.gr
authors.forename: C K
authors.initials: CK
authors.lastname: Yiannakopoulos
authors.forename: E
authors.initials: E
authors.lastname: Mataragas
authors.forename: E
authors.initials: E
authors.lastname: Antonogiannakis
mesh_terms: D000328:Adult; D006801:Humans; D008297:Male; D009119:Muscle Contraction / Q000502:physiology*; D010329:Patella / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D017847:Patellar Ligament / Q000000981:diagnostic imaging / Q000502:physiology*; D052097:Quadriceps Muscle / Q000000981:diagnostic imaging / Q000502:physiology*; D011859:Radiography; D016474:Weight-Bearing / Q000502:physiology*