J Bone Joint Surg Br
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J Bone Joint Surg Br · Jul 2008
The effect of quadriceps contraction during weight-bearing on four patellar height indices.
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. ⋯ 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.
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Children presenting with Perthes' disease before their sixth birthday are considered to have a good prognosis. We describe 166 hips in children in this age group. The mean age at onset of the disease was 44 months (22 to 72). ⋯ We confirm that the prognosis in Perthes' disease is generally good when the age at onset is less than six years. In severe disease there is no significant difference in outcome after conservative or operative treatment (p > 0.05). Catterall grade-III hips had a better outcome according to the Stulberg and Mose criteria than Catterall grade-IV hips, regardless of the method of treatment.