Abstract
BackgroundAs one of the classical total hip arthroplasty (THA) approaches, the posterior approach is widely used. However, there is a lack of in-depth quantitative researches on the surgical-related injury to the hip external rotators. The purpose of this study is to quantificationally analyse the surgical injury of hip external rotators after posterior THA and explore the effect of the muscle repair on the muscle recovery using the MRI three-dimensional reconstruction technique combined with the clinical assessment.MethodsSixty five patients were eligible to receive a unilateral cementless THA via the posterior approach. During operation, the piriformis tendon was reattached but it was not applicable for the internal obturator muscle. We performed three-dimensional MRI reconstruction of bilateral piriformis and internal obturator muscle along with clinical assessment preoperatively, 6, 12 and 52 weeks postoperatively.ResultsBilateral piriformis and internal obturator muscle were homogeneous preoperatively. Compared with the contralateral side, the volume atrophy and fat-muscle ratio of the piriformis on the operated side increased inconspicuously by 1.64%, 0.26% (p = 0.062, p = 0.071) at 6 weeks and 1.33%, 0.20% (p = 0.057, p = 0.058) at 12 weeks, while 7.28%, 2.09% and 15.71%, 5.14% for the internal obturator muscle (p < 0.01). Up to 52 weeks, the pirformis also showed significant muscle atrophy as well as fatty infiltration (increased by 7.79%, 4.21%; p < 0.01), and 24.18%, 11.91% for the internal obturator muscle (p < 0.01).ConclusionThe THA via posterior approach significantly harms the hip external rotators and the early hip external rotation function. The effective repair could be conducive to the early postoperative recovery of the hip external rotators.Trail registrationThe study has been registered in Chinese Clinical Trial Registry (ChiCTR) before the clical trial started, the Clinical Trial Registry Number is ChiCTR-IOR-17013007. Registered 17 October 2017. The Trial registration is prospective registration.
Highlights
As one of the classical total hip arthroplasty (THA) approaches, the posterior approach is widely used
The aim of this study was to address the following questions using the magnetic resonance imaging (MRI) three-dimensional reconstruction technique in combination with the clinical assessment: 1) What were the changes in the muscle morphology of hip external rotators and the external rotation function after posterior THA? 2) Whether the repair of external rotators contributed to a better amelioration in the muscle morphology postoperatively?
At 6 weeks postoperatively, compared with the contralateral side, the muscle volume of piriformis on the operated side decreased by 1.64% (p = 0.062), while 7.28% for the internal obturator muscle (p < 0.01)
Summary
As one of the classical total hip arthroplasty (THA) approaches, the posterior approach is widely used. The purpose of this study is to quantificationally analyse the surgical injury of hip external rotators after posterior THA and explore the effect of the muscle repair on the muscle recovery using the MRI three-dimensional reconstruction technique combined with the clinical assessment. The posterior approach, known as the “Kocher-Langenbeck approach”, is the most frequently used among multitudinous THA approaches [1, 2]. Concerning this approach, a widespread controversy has been always existed over the surgical injury of the hip external rotators and whether to repair them or not. All of these studies were based on the two-dimensional MRI single layer analysis so that the results lacked precision and objectiveness [9]
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