[Clinical effect of Corail femoral prosthesis with different offset in total hip arthroplasty].

Objective: To explore the early clinical efficacy of primary total hip arthroplasty(THA) with Corail standard stems (KS type) and high offset stems (KHO type), by analyzing the postoperative radiographic parameters of different offset of femoral components with Corail stem which has a neck-shaft angle of 135 ° in unilateral primary THA, by comparing the measurement results on both sides and analyzing the reconstruction of the postoperative femoral offset and the hip joint function recovery.

Methods: A retrospective analysis was made of 186 patients with unilateral hip joint lesions who underwent the first total hip arthroplasty with Johnson & Johnson Corail prostheses from January 2015 to June 2017. According to the use of femoral prostheses with different eccentricities during the operation, the patients were divided into high eccentricity group and standard eccentricity group. In the high eccentricity group, there were 52 cases of Corail high eccentricity prosthesis(KHO type), including 20 females and 32 males;aged 21 to 71 years old with an average of(50.6±13.2) years;body mass index(BMI) was (26.0±4.1) kg/m. The standard eccentricity group included 134 Corail standard femoral stem prostheses(KS type), 57 females and 77 males;aged 18 to 77 years old with an average of (47.3±14.0) years;BMI was (25.3±3.5) kg/m. The abduction arm, femoral eccentricity, acetabular eccentricity and the length difference of lower limbs were measured on the postoperatively positive X-ray film of the hip joint. Harris score and related complications were recorded before and after the operation, and the stability of the prosthesis was analyzed.

Results: There were significant differences in femoral eccentricity, joint eccentricity and abduction arm between the affected side and the healthy side in the high eccentricity group(<0.05). There were significant differences in femoral eccentricity and acetabular eccentricity between the affected side and the healthy side in the standard eccentricity group(<0.05). There were significant differences in combined eccentricity, abduction arm and length of lower limbs between two groups(<0.05). In the high eccentricity group, the abduction arm of the affected hip joint was positively correlated with the femoral eccentricity, acetabular eccentricity and joint eccentricity(=0.633, <0.001;=0.384, =0.005;=0.690, <0.001). The same results were also obtained in the healthy side(=0.688, <0.001;=0.574, <0.001;=0.765, <0.001). In the standard eccentricity group, the abduction arm of the affected hip joint was positively correlated with the femoral eccentricity, acetabular eccentricity and combined eccentricity(=0.734, <0.001;=0.418, <0.001;=0.749, <0.001). The same results were also obtained in the healthy side(=0.775, <0.001;=0.397, <0.001;=0.773, <0.001). The difference of the length of both lower limbs was significantly correlated with the difference of bilateral joint eccentricity and bilateral abduction arm (=0.376, =0.006;=-0.346, =0.012). There was no significant correlation between the difference of the length of both lower limbs and the difference of bilateral joint eccentricity and bilateral abduction arm (=-0.009, =0.919;=-0.036, =0.682). There was no significant difference in Harris score between two groups at the last follow-up(>0.05). At the last follow-up, Trendelenburg was negative in all patients in both groups, and the prostheses were stable.

Conclusion: Both Corail standard stem and high offset stem may be effectively reconstruct the femoral offset, reconstruct the anatomical structure and biomechanics of the hip joint, and maintain the length of lower limbs and the stability of the hip joint in the unilateral primary total hip arthroplasty. Although the offset of the femur was not reconstructed normally in some cases, the stability of the components and postoperative function were not affected.