[Case-control study on effect of anterolateral and posterolateral approaches on early postoperative hip abductor strength in total hip arthroplasty].

OBJECTIVE: To compare the difference of early postoperative hip abductor strength and function between improved Gibson anterolateral approach (group A) and conventional Gibson posterolateral approach (group B) in patients who had underwent total hip arthroplasty (THA).

METHODS: Among 149 patients performing total hip arthroplasty,130 patients were followed up and were randomly divided into two groups (19 unqualified cases were excluded). Group A included 65 cases who underwent anterolateral approach, and the other group included 65 cases who underwent posterolateral approach. In the group A, male:female = 26:39,with an average age of (72.5 ± 8.3) years old, BMI of (24.7 ± 3.7) kg/m², and hip abductor strength of (1.08 ± 0.49) N · m/kg. In the group B, male:female = 30:35, with an average age of (71.6 ± 7.1) years old, BMI of (25.5 ± 3.9) kg/m², and hip abductor strength of (1.05 ± 0.51) N · m/kg. In the age-related control group, male:female = 33:32, with an average age of (73.1 ± 7.5) years old, BMI of (24.2 ± 3.8) kg/m², and hip abductor strength of (1.17 ± 0.53) N · m/kg. The age, BMI, hip abductor strength, anatomy of surgical approach, hip abduction angles and Harris score in all patients were evaluated at the day before surgery and at 1, 2, 3, 6, and 12 months after surgery. All preoperative clinical data (age, BMI and abductor strength of the uninjured side limb ) of these cases had no significant differences.

RESULTS: At 1, 2, 3, 6, and 12 months after surgery, the hip abductor strength in group A were (0.53 ± 0.13), (0.66 ± 0.21), (0.85 ± 0.15), (0.95 ± 0.19), (1.03 ± 0.13) N · m/kg respectively, while in group B were (0.46 ± 0.14), (0.57 ± 0.18), (0.78 ± 0.12), (0.85 ± 0.18), (0.98 ± 0.14) N · m/ kg respectively.The differences between the two groups at the 6th months after operation were significant; the hip abduction angles in group A were (25.35 ± 4.31)°, (36.53 ± 5.13)°, (48.07 ± 1.62)°, (61.53 ± 1.77)°, (68.62 ± 3.16)°,while in group B were (23.47 ± 2.41)°, (33.42 ± 4.23)°, (46.64 ± 2.51)°, (60.96 ± 1.75)°, (67.47 ± 4.36)°. The differences between the two groups at the 3rd month after operation were significant. Harris score in the group A were 72.23 ± 2.57, 79.36 ± 3.91, 84.75 ± 3.17, 88.63 ± 2.16, 95.21 ± 1.37 repectively ; while in the group B were 71.58 ± 3.62, 78.96 ± 2.21, 83.97 ± 3.57, 87.92 ± 2.94, 94.83 ± 1.62 respectively. There were no significant differences between them.

CONCLUSION: Owing to less muscles interrupted, the THA with improved Gibson anterolateral approach offers a better improvement in earlier hip abductor strength and abduction angle compared with the conventional surgery.