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; and 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; and 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. The patients in this study were on the same degeneration stage (IV stage) according to Kellgren–Lawrence (K–L) grading scale(15). This study was approved by the Ethics Committee of Jinhua Central Hospital (approval number LGF19H060005). All of the patients included in this study provided signed informed consent.
Surgical methods
All surgeries were performed by the same surgical team comprising a chief surgeon (15 years of experience) and two attending surgeons (6 years of experience). All patients were implanted a cementless prosthesis (Zimmer, USA) under general anesthesia through tracheal intubation. The blood lost during the and within 6 hours postoperatively was collected using an autologous blood recovery system, and the volume of blood loss was recorded. In patients with intraoperative blood loss >500 mL, autologous blood transfusion was conducted. The patient grouping was done according to the administered surgical approach, which was based on the disease condition of the patient. However, the standard surgery was suggested for obese patients.
Surgery in the standard group
In the standard group, the patient was first administered general anesthesia and then 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. Then, a T-shaped incision was made to cut open the articular capsule. The hip joint was then dislocated and the femoral neck was resected at 1 cm above the lesser trochanter. Next, 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 were performed at the proximal end of the femur 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
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 was made on the affected hip. 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. Later, the procedure described for the standard group was performed, with hip joint dislocation by internal rotation, hip bending, and knee bending. Then, osteotomy was performed at the femoral neck, 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 the patient’s condition and surgical risk before anesthesia) (16), visual analog scale (VAS) score for pain, and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score, and Oxford hip score (OHS), were collected. Intra- and postoperative 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 degree of injury before and at 48 hours postoperatively, as well as changes in inflammation-related indicators, including creatine kinase (CK), myoglobin, and 72-hour 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 were recorded at 8 weeks postoperatively. Pain intensity (1 to 7 days postoperatively) was assessed using the VAS. The WOMAC score was used to assess the severity of arthritis and effects of the treatment preoperatively and at 8 weeks postoperatively, according to symptoms and signs of the patient (17). The Harris score and OHS score were used to assess the recovery of hip joint functions. X-ray and CT were performed to assess the position of the prosthesis after operation (18).
The patients were followed up twice through clinical visits or telephone calls at 2 and 8 weeks postoperatively. The Harris score, OHS, WOMAC score, X-ray film, and CT scan were assessed and recorded during each follow-up session.
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 were represented using mean ± standard deviation (SD) and those with skewed distribution were described as median and range. Independent samples t-test was performed for comparisons between the two groups. The chi-squared test was carried out for comparing categorical data. Multi-factor analysis of variance was adopted for assessing the postoperative Harris, WOMAC, and Oxford scores, as well as VAS score on day 7 postoperatively. P < 0.05 was considered statistically significant.