TY - JOUR
T1 - Does High Hip Center Decrease Range of Motion in Total Hip Arthroplasty? A Computer Simulation Study
AU - Komiyama, Keisuke
AU - Nakashima, Yasuharu
AU - Hirata, Masanobu
AU - Hara, Daisuke
AU - Kohno, Yusuke
AU - Iwamoto, Yukihide
N1 - Funding Information:
This work was supported by a Grant-in-Aid for Scientific Research from the Japan Society for the Promotion of Science (No. 15K10450).
Publisher Copyright:
© 2016 Elsevier Inc.
PY - 2016/10/1
Y1 - 2016/10/1
N2 - Background High placement of a cementless acetabular cup is often required to have sufficient bone coverage in hip dysplasia. We examined whether a high hip center decreases the postoperative range of motion (ROM) in total hip arthroplasty. Methods Using a computer software, ROM and bone coverage were examined in 32 patients with unilateral osteoarthritis of the hip with Crowe type II or III hip dysplasia. The cup was placed at the anatomic hip center and moved vertically in 5-mm increments. Vertical center of rotation (V-COR) was defined as the distance from the head center to the interteardrop line. The required ROM was defined as flexion ≥110°, internal rotation (IR) at 90° flexion ≥30°, extension ≥30°, and external rotation ≥30°. We determined the V-COR to satisfy the required ROM and cup center-edge angle (Cup-CE) ≥0°. Results Only 40.6% of the patients satisfied Cup-CE ≥0° at the anatomic hip center. Bone coverage increased with the peak at 30, 35 mm of V-COR (90.6% satisfied Cup-CE ≥0°) and decreased at ≥40 mm. Higher V-COR resulted in lower range of flexion and IR, but increased the range of extension and external rotation. The cutoff value from the receiver-operating characteristic curve for both flexion and IR was a V-COR of 35 mm. Conclusion The higher hip center gained more bone coverage but decreased the range of hip flexion and IR. Acceptable V-COR in hip dysplasia was around 35 mm, about 20 mm above the true hip center, in terms of ROM.
AB - Background High placement of a cementless acetabular cup is often required to have sufficient bone coverage in hip dysplasia. We examined whether a high hip center decreases the postoperative range of motion (ROM) in total hip arthroplasty. Methods Using a computer software, ROM and bone coverage were examined in 32 patients with unilateral osteoarthritis of the hip with Crowe type II or III hip dysplasia. The cup was placed at the anatomic hip center and moved vertically in 5-mm increments. Vertical center of rotation (V-COR) was defined as the distance from the head center to the interteardrop line. The required ROM was defined as flexion ≥110°, internal rotation (IR) at 90° flexion ≥30°, extension ≥30°, and external rotation ≥30°. We determined the V-COR to satisfy the required ROM and cup center-edge angle (Cup-CE) ≥0°. Results Only 40.6% of the patients satisfied Cup-CE ≥0° at the anatomic hip center. Bone coverage increased with the peak at 30, 35 mm of V-COR (90.6% satisfied Cup-CE ≥0°) and decreased at ≥40 mm. Higher V-COR resulted in lower range of flexion and IR, but increased the range of extension and external rotation. The cutoff value from the receiver-operating characteristic curve for both flexion and IR was a V-COR of 35 mm. Conclusion The higher hip center gained more bone coverage but decreased the range of hip flexion and IR. Acceptable V-COR in hip dysplasia was around 35 mm, about 20 mm above the true hip center, in terms of ROM.
UR - http://www.scopus.com/inward/record.url?scp=84962644077&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84962644077&partnerID=8YFLogxK
U2 - 10.1016/j.arth.2016.03.014
DO - 10.1016/j.arth.2016.03.014
M3 - Article
C2 - 27067755
AN - SCOPUS:84962644077
SN - 0883-5403
VL - 31
SP - 2342
EP - 2347
JO - Journal of Arthroplasty
JF - Journal of Arthroplasty
IS - 10
ER -