Masato Kiyohara1, Satoshi Hamai2,3, Daisuke Hara1, Daisuke Fujiyoshi4, Satoru Harada1, Kenichi Kawaguchi1,4, Yasuharu Nakashima1. 1. Department of Orthopaedic Surgery, Faculty of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan. 2. Department of Orthopaedic Surgery, Faculty of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan. hamachan@ortho.med.kyushu-u.ac.jp. 3. Rehabilitation Medicine, Kyushu University Hospital, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan. hamachan@ortho.med.kyushu-u.ac.jp. 4. Rehabilitation Medicine, Kyushu University Hospital, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan.
Abstract
INTRODUCTION: This study examined whether the component position or muscle strength affects the cup-head translation under in vivo weight-bearing conditions after total hip arthroplasty (THA). We hypothesized that there was a correlation between the hip offset or abductor strength and cup-head translation during gait. MATERIALS AND METHODS: We prospectively evaluated 31 patients undergoing unilateral cementless primary THA. The cup height, cup/stem offset, and limb length discrepancy were measured on anterior-posterior bilateral hip radiographic images. The isometric muscle strength of the lower limbs was quantified using a handheld dynamometer. Continuous radiographic images were recorded during gait, and cup-head translation was analysed using a computer-assisted method. RESULTS: The average cup height, cup/stem offset, and limb length discrepancy were - 3.8 ± 5.1 mm, 1.2 ± 5.2 mm/- 0.7 ± 7.7 mm, and - 2.1 ± 5.2 mm, respectively. The average hip abductor/flexor and knee extensor strength were 86% ± 18%/85% ± 17% and 88% ± 17% of the contralateral healthy hip, respectively. The average cup-head translation during swing phase of gait was - 0.003 ± 0.31 mm. Multiple regression analyses found no significant independent predictors of cup-head translation (p > 0.05). CONCLUSIONS: The component position or muscle strength did not significantly influence cup-head translation during gait after well-positioned primary THA.
INTRODUCTION: This study examined whether the component position or muscle strength affects the cup-head translation under in vivo weight-bearing conditions after total hip arthroplasty (THA). We hypothesized that there was a correlation between the hip offset or abductor strength and cup-head translation during gait. MATERIALS AND METHODS: We prospectively evaluated 31 patients undergoing unilateral cementless primary THA. The cup height, cup/stem offset, and limb length discrepancy were measured on anterior-posterior bilateral hip radiographic images. The isometric muscle strength of the lower limbs was quantified using a handheld dynamometer. Continuous radiographic images were recorded during gait, and cup-head translation was analysed using a computer-assisted method. RESULTS: The average cup height, cup/stem offset, and limb length discrepancy were - 3.8 ± 5.1 mm, 1.2 ± 5.2 mm/- 0.7 ± 7.7 mm, and - 2.1 ± 5.2 mm, respectively. The average hip abductor/flexor and knee extensor strength were 86% ± 18%/85% ± 17% and 88% ± 17% of the contralateral healthy hip, respectively. The average cup-head translation during swing phase of gait was - 0.003 ± 0.31 mm. Multiple regression analyses found no significant independent predictors of cup-head translation (p > 0.05). CONCLUSIONS: The component position or muscle strength did not significantly influence cup-head translation during gait after well-positioned primary THA.
Entities:
Keywords:
Hip abductor strength; Hip offset; Limb length discrepancy; Replaced hip; Treadmill