Abstract
BackgroundIn total hip arthroplasty performed via the posterior approach, repairing the posterior soft tissues is a conventional method for preventing postoperative prosthetic joint dislocation. The aim of this study was to verify whether obturator externus repair played the main role and what was the mechanism of the repair preventing the dislocation.MethodsIncluded were 188 patients who underwent primary cementless total hip arthroplasty via the posterior approach. The patients were divided into a repair group (n = 94) and a non-repair group (n = 94). Patients of repair group received additional obturator externus repair while patients of non-repair group did not. The range of motion of hip joint was assessed before and after operation. Data were compared between the two groups. A p value < 0.05 was considered statistically significant.ResultsBefore operation and under anesthesia, with regard to internal rotation of hip joint, the mean values of repair and non-repair groups were 24° ± 16/28° ± 15 (p = 0.2933). The mean values of the groups were 13° ± 8/15° ± 9 immediately after repair (p = 0.5672). Range of internal rotation 1 year after operation were 15° ± 8/19° ± 9 (p = 0.0139). Specifically, the values in repair group were lower than those in non-repair group. During a 5-year period of postoperative follow-up, hip joint dislocation occurred in one patient of non-repair group. No dislocation was observed in repair group.ConclusionWhen THA is performed via the posterior approach, repairing the obturator externus may decrease the risk of postoperative prosthetic joint dislocation by reinforcing the posterior soft tissues of the hip joint.Level of evidenceTherapeutic study, Level IVa.
Highlights
The posterior approach is the most commonly used approach for total hip arthroplasty (THA), but is associated with a high incidence of postoperative prosthetic joint dislocation (PPJD) [1,2,3], a serious complication
The obturator externus tends to retreat into the deeper wound when it is dissected from the greater trochanter, rendering it difficult to identify the stump of obturator externus
Our study showed that obturator externus repair, as a part of posterior repair in THA via the posterior approach, did not impair deep flexion of the hip joint
Summary
The posterior approach is the most commonly used approach for total hip arthroplasty (THA), but is associated with a high incidence of postoperative prosthetic joint dislocation (PPJD) [1,2,3], a serious complication. The early reports showed that repairing the posterior soft tissues could prevent PPJD [4,5,6,7,8,9,10,11,12], but it is still unclear which posterior structure plays the main role and what is the mechanism by which such repair prevents PPJD. THA via the posterior approach involves four structures, i.e., (1) the piriformis tendon, (2) the conjoined tendon formed by the superior gemellus, obturator internus, and inferior gemellus, (3) the obturator externus, and (4) the posterior joint capsule. Gudena et al [16] described the functional anatomy of the obturator externus in 2015 Those studies showed that the piriformis tendon and short external rotators are the important structures for preventing PPJD. In total hip arthroplasty performed via the posterior approach, repairing the posterior soft tissues is a conventional method for preventing postoperative prosthetic joint dislocation. The aim of this study was to verify whether obturator externus repair played the main role and what was the mechanism of the repair preventing the dislocation
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