Abstract
INTRODUCTION
The Dorr Bone Classification, devised in 1993 is commonly used to categorize bone types prior to hip reconstruction. The purpose of the present study is to quantify the Dorr classification system using 4 morphologic parameters – morphologic cortical index (MCI), canal-flare index (CFI), canal-bone ratio (CBR), and canal-calcar ratio (CCR).
METHODS
816 hips were reviewed. Demographic data reviewed includes age, sex, and laterality. Each hip was reviewed by 2 separate evaluators for Dorr classification. The MCI, CCR, CBR, and CFI were calculated for each hip on anteroposterior radiographs (Fig 1). One-way ANOVA statistical analysis was used to examine if there are mean differences for each measurement. IRB approval was obtained before collection of data.
RESULTS
The average age of patients was 61 (range 20–96). There were 367 left hips and 449 right hips. The prevalence of Dorr A was 45.8%. The prevalence of Dorr B bone was 38.9% and of Dorr C bone was 15.3%.
One-way ANOVA analysis confirmed the mean differences for each measurement. Measurements of the MCI, CCR, CBR, and CFI were statistically significantly different between the three types of bone. The MCI and CFI were significantly higher in Type A than Type B and higher in Type B than Type C. The CBR and CCR were significantly lower in Type A than Type B and lower in Type B than Type C.
DISCUSSION
To our knowledge, the present study is the first to attempt to quantify the Dorr Bone classification system using MCI, CCR, CBR, and CFI using a large series of patients. Classification of the proximal femur geometry is important as it may play a role in implant fixation for patients undergoing total hip arthroplasty (THA). Furthermore, this information can be used to guide future implant choices.
