Abstract
BackgroundWhile cam resection is essential to achieve a good clinical result with respect to femoroacetabular impingement (FAI), it is unclear whether it should also be performed in cases of borderline developmental dysplasia of the hip (DDH) with a cam deformity. The aim of this study was to evaluate improvements in range of motion (ROM) in cases of cam-type FAI and borderline DDH after virtual osteochondroplasty using a computer impingement simulation.MethodsThirty-eight symptomatic hips in 31 patients (11male and 20 female) diagnosed with cam-type FAI or borderline DDH were analyzed. There were divided into a cam-type FAI group (cam-FAI group: 15 hips), borderline DDH without cam group (DDH W/O cam group: 12 hips), and borderline DDH with cam group (DDH W/ cam group: 11 hips). The bony impingement point on the femoral head-neck junction at 90° flexion and maximum internal rotation of the hip joint was identified using ZedHip® software. Virtual osteochondroplasty of the impingement point was then performed in all cases. The maximum flexion angle and maximum internal rotation angle at 90° flexion were measured before and after virtual osteochondroplasty at two resection ranges (i.e., slight and sufficient).ResultsThe mean improvement in the internal rotation angle in the DDH W/ cam group after slight resection was significantly greater than that in the DDH W/O cam group (P = 0.046). Furthermore, the mean improvement in the internal rotation angle in the DDH W/ cam and cam-FAI groups after sufficient resection was significantly greater than that in the DDH W/O cam group (DDH W/ cam vs DDH W/O cam: P = 0.002, cam-FAI vs DDH W/O cam: P = 0.043).ConclusionVirtual osteochondroplasty resulted in a significant improvement in internal rotation angle in DDH W/ cam group but not in DDH W/O cam group. Thus, borderline DDH cases with cam deformity may be better to consider performing osteochondroplasty.
Highlights
While cam resection is essential to achieve a good clinical result with respect to femoroacetabular impingement (FAI), it is unclear whether it should be performed in cases of borderline developmental dysplasia of the hip (DDH) with a cam deformity
The mean body mass index (BMI) in the cam-FAI group was significantly higher than that in the DDH W/O cam group (P = 0.012). positive crossover sign was seen in 9 hips out of 38 hips, and it was seen most in cam-type FAI group
Here, we demonstrated that patients with borderline DDH with cam and cam-type FAI showed similar and significant improvement in the internal rotation angle after virtual osteochondroplasty; the procedure was not effective for those with borderline DDH without cam
Summary
While cam resection is essential to achieve a good clinical result with respect to femoroacetabular impingement (FAI), it is unclear whether it should be performed in cases of borderline developmental dysplasia of the hip (DDH) with a cam deformity. FAI causes hip pain during squatting or deep flexion and may reduce range of motion (ROM) at that joint [4] These morphological abnormalities can be corrected by osteochondroplasty, which releases the bony impingement and improves ROM. While cam resection is essential to achieve a good clinical result with respect to FAI [9, 10], it is unclear whether it should be performed in cases of borderline DDH In this regard, computer simulated virtual osteochondroplasty may provide the answer from the point of view of improvement in ROM
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