Patients
This prospective study included consecutive patients who underwent THA in the Orthopedics Department of Jinhua Central Hospital between June 2017 and June 2018. Inclusion criteria were: 1) age ≥18 years; 2) THA for diseases such as osteonecrosis of the femoral head, hip osteoarthritis, and femoral neck fracture; 3) no previous hip arthroplasty. Exclusion criteria were: 1) traumatic arthritis 2) language or communication difficulties, or psychiatric disorders that could not be followed up; 3) concurrent severe internal diseases or severe osteoporosis; 4) BMI >30; 5) old acetabulum fractures accompanied by pelvic deformities or acetabular defects. The patients were assigned to the corrective and standard groups based on the applied surgical methods. This study was approved by the Ethics Committee of Jinhua Central Hospital (approval number LGF19H060005). All the included patients provided signed informed consent.
Surgical methods
All surgeries were performed by the same surgical team comprising 1 chief surgeon (15 years of experience) and 2 attending surgeons (6 years of experience). All patients were implanted a cementless prosthesis (Zimmer, USA) under general anesthesia by tracheal intubation. The blood lost during the operation and within 6 h postoperatively was collected with an autogenous blood recovery system, and blood loss volume was recorded. In patients with intraoperative blood loss >500 ml, autogenous blood transfusion was conducted. The patients were grouped into the corrective and standard groups, respectively, according to the administered surgical approaches, which were selected by surgeons based on disease condition and patient wishes. However, standard surgery was suggested for obese patients.
Surgery in the standard group
After general anesthesia, the patient was placed in the lateral position on the unaffected side, followed by routine disinfection and draping. A line of about 14 cm was drawn from the proximal end of the greater trochanter of the femur to the distal end. Next, the skin, subcutaneous tissues, and fascia were incised layer by layer, and blunt dissection of the gluteus maximus was performed. Next, the hip joint was slightly internally rotated to expose the piriformis muscle, the internal obturator muscle, the gemellus superior and inferior, and the quadrate muscle of the thigh. Muscle terminations were resected with an electric scalpel, and the muscles were folded upward to expose the articular capsule. A T-shaped incision was made to cut open the articular capsule. This was followed by hip joint dislocation and femoral neck resection at 1 cm above the lesser trochanter. Then, the femoral head was retrieved with a special apparatus, with the femoral neck trimmed to an appropriate length. After clearing the acetabular margin, the ligamentum capitis femoris was resected and residual soft tissues in the occipital area were cleared to expose the osseous acetabulum. Acetabular prostheses of different sizes were implanted to determine the ideal match and the osseous coverage. An appropriate prosthesis was selected and placed in the acetabular cup at the position of 45° abduction and 15° anteversion, and screws were used for fixation if necessary. The affected limb was upheld and kept adducted as much as possible. Grooving and reaming at the proximal end of the femur was performed to obtain the ideal size, and the testing model was placed. The femoral head was implanted, and hip joint reduction was performed. The lower leg length, range of motion and hip joint stability were examined.
Surgery in the corrective group
After general anesthesia, the patient was placed in the lateral position on the unaffected side, and routine disinfection and draping were performed. A posterolateral incision at the affected hip was made. Then, an oblique, arch-shaped incision of about 14 cm was made posterior to the greater trochanter of the femur. Next, the skin, subcutaneous tissues, and the fascia were incised, and the quadrate muscle of the thigh, the inferior gemellus, and the distal internal obturator muscle were resected along the posterior margin of femoral tuberosity. The internal obturator muscle was vertically incised, and an L-shaped incision was made for the articular capsule. The tendon of the piriformis muscle, the gemellus superior, the upper part of the internal obturator muscle, and the posterosuperior articular capsule were preserved. Afterwards, the procedures described for the standard group were performed, with hip joint dislocation by internal rotation, hip bending, and knee bending. Then, osteotomy at the femoral neck was performed while the femoral calcar was preserved, and the femoral head was retrieved with a special apparatus. The cavitas glenoidalis and the round ligament were resected, and the acetabular margin was cleared to expose the osseous acetabulum. Acetabular prostheses were implanted to determine the ideal match, and screws were used for fixation if necessary. The affected limb was upheld and kept adducted as much as possible, with grooving and reaming at the proximal end of the femur to obtain the ideal size. Then, the testing model was placed. The femoral head was implanted, and hip joint reduction was performed. The lower leg length, range of motion and hip joint stability were examined.
Data collection and follow up
The baseline data of patients in both groups, including sex, age, body mass index (BMI), initial diagnosis, American Society of Anesthesiologists Classification (ASA) score (assessed according to patient condition and surgical risk before anesthesia) (15), Western Ontario, visual analog scale (VAS) score for the pain, and McMaster Universities Osteoarthritis Index (WOMAC) score, and Oxford hip score (OHS), were collected. Intra- and post- operative parameters in both groups, including incision length, operation time, intraoperative blood loss volume, blood transfusion volume, postoperative drainage volume, and hospital stay, were recorded. The injury degree before and at 48h postoperatively, as well as changes of inflammation-related indicators, including creatine kinase (CK), myoglobin, and 72-h postoperative C-reactive protein (CRP), versus preoperative levels, were also recorded. Postoperative parameters, including times to bedside ambulation, independent stair use and joint dislocation rates 8 weeks postoperative, were recorded. Pain intensity (postoperative 1 to 7 days) was assessed using the VAS. The Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score was used to assess arthritis severity and treatment effects preoperatively and at 8 weeks postoperatively, according to patient symptoms and signs (16). The Harris score and OHS score were used to assess the recovery of hip joint functions. X-ray and CT were performed to assess prosthesis position after operation (17).
The patients were followed up twice by clinical visits or telephone calls at the second and the eighth weeks postoperatively. The Harris score, OHS, WOMAC score, X-ray film and CT scan were assessed and recorded at each follow-up.
Statistical analysis
SPSS22.0 (IBM, Armonk, NY, USA) was used for statistical analysis. GraphPad Prism 7.0 (GraphPad, San Diego, USA) was used for graphing. Continuous variables with normal distribution are mean ± standard deviation (SD); those with skewed distribution were described as median and range. Independent samples t-test was performed for comparisons between the two groups. The chi-square test was carried out for comparing categorical data. Multi-factor analysis of variance was adopted for assessing postoperative Harris, WOMAC and Oxford scores, as well as VAS score on postoperative day 7. P<0.05 was considered statistically significant.