CAN PREOPERATIVE CLASSIFICATIONS FOR HIP DYSPLASIA PREDICT RESTORATION OF OPTIMAL HIP ROTATION CENTRE?

Abstract

Introduction: Operative treatment of secondary osteoarthritis due to congenital hip disease (CHD) in adults presents a challenging issue. Various classifications have been proposed for congenital hip disease in search for the best treatment option. Aim of this prospective study is to find measurements important in preoperative planning and their correlation with postoperative results.

Materials and Methods: We have included 64 patients (70 hips) with CHD consecutively scheduled for operation. Preoperatively congenital hip disease was classified according to Crowe, Hartofilakidis and Eftekhar and center of rotation was determined using Ranawat’s method. Distance between ideal and actual center rotation was measured. Further, distance between medial acetabular wall and medial pelvic rim (medial bone bulk) in the line of ideal center of rotation was measured. Another measurement was distance between ideal acetabular roof point and medial pelvic rim. On the postoperative radiographs centre of the femoral head was recorded.

Correlation between Crowe, Hartofilakidis and Eftekhar classifications with distance between ideal and postoperative center rotation and medial bone bulk were calculated using Pearson correlation. Correlation was also analyzed using information about distance between ideal acetabular roof point and medial pelvic rim.

Results: Data analysis showed that there is the strongest connection between degree of CHD determined using Eftaker classification and distance between ideal and actual rotation center (r=0.417, p=0.011). Crowe and Hartofilakidis classifications also shows statistically significant connection, however not that strong (r= 0.384, p=0.021 for Crowe and r=0.373, p=0.025 for Hartofilakidis). Eftaker classification shows the strongest correlation with medial bone bulk r=0.425, a p=0.010. Similar is Crowe classification (r=0.341, p=0.042), while there is no statistically significant correlation with Hartofilakidis classification. Results also shows that when there is higher degree of congenital hip disease there is thinner bone bulk in line of ideal acetabular roof (for Crowe r= −0.360, p=0.031, for Hartofilakidis r= −0.354, p=0.34).

Conclusion: Results show that severity of dysplasia according to Crowe, Hartofilakidis and Eftekhar correlates with postoperative position of rotation center. Eftekhar classification gives the best insight to how much medial bone bulk is available. For bone bulk on the acetabular roof predictions can be made using both Crowe and Hartofilakidis system. However, one classification still does not provide with all information we found important for correct endoprothesis placement in relation to center of rotation especially about acetabular depth, and bone mass on the medial acetabular wall and acetabular roof.