Objective: To investigate the clinical efficacy of total hip arthroplasty (THA) via the direct anterior approach (DAA) for the treatment of hip ankylosis in the lateral position.
Methods: A retrospective analysis was performed on the clinical data of 24 patients (39 hips) who underwent THA via the DAA in the lateral position for the treatment of hip ankylosis between January 2016 and December 2018. We performed bilateral THA for fifteen patients and unilateral THA for nine patients. Operation time, intraoperative blood loss, length of incisions, straight leg-raising time, length of postoperative hospital stay, operation-related complication, prosthesis position, radiological outcomes, postoperative pain relief (evaluated by VAS) and functional rehabilitation [evaluated by Harris hip score and range of motion (ROM)] were analyzed to determine clinical efficacy. These clinical data were compared and statistically analyzed with the clinical data of another 23 patients (28 hips) who underwent THA via the posterolateral approach (PLA) for the treatment of hip ankylosis in the lateral position.
Results: Follow-up was performed at 12-15 months. The incision length in the DAA group and the PLA group was (11.12 ± 1.69 vs. 14.36 ± 3.42) cm, the intraoperative blood loss was (371.25 ± 120.55 vs. 396.80 ± 101.21) ml, the operation time was (122.47 ± 25.40 vs. 138.47 ± 24.45) min, the postoperative hospital stay was (9.59 ± 4.62 vs. 12.08 ± 3.58) days, and the straight leg elevation time was (9.20 ± 2.12 vs. 12.34 ± 3.25) days, respectively. The prosthesis of the two groups was in a good position: The average angle of cup anteversion in the DAA group and the PLA group was (10.76 ± 2.84 vs. 15.36 ± 3.42)°, and the average angle of cup abduction in the DAA group and the PLA group was (40.00 ± 3.45 vs. 41.21 ± 2.85)° (P > 0.05). The VAS score, ROM and Harris score at different follow-up time points were significantly improved in the two groups compared with those before surgery. In the first 3 months after surgery, the VAS score, ROM and Harris score of the DAA group were significantly better than those of the PLA group (P < 0.05), but with the extension of the follow-up time, there was no significant difference in the above indicators between the two groups (P > 0.05). One case of greater trochanteric fracture occurred in the DAA group. Two cases of hip posterior dislocations occurred in the PLA group, and no dislocations occurred after manual closed reduction and hip fixation in bed for 1 month to the last follow-up. No complications such as infection, deep vein thrombosis, fat embolism, prosthesis loosening, limb length inequality or joint dislocation were reported.
Conclusion: THA via the DAA for the treatment of hip ankylosis in the lateral position was safe and effective and had the advantage of reduced trauma, quicker recovery of hip function, lower incidence of postoperative dislocation and ability to expose the acetabulum fully and fit the prosthesis properly, providing satisfactory clinical efficacy.
Keywords: Ankylosing spondylitis (AS); Direct anterior approach (DAA); Lateral position; Posterolateral approach (PLA); Total hip arthroplasty (THA).