Chalmers Brian P, Pallante Graham D, Taunton Michael J, Sierra Rafael J, Trousdale Robert T
Department of Orthopedic Surgery, Mayo Clinic, Rochester, MN, USA.
Clin Orthop Relat Res. 2018 Feb;476(2):305-312. doi: 10.1007/s11999.0000000000000026.
Revision THA to treat recurrent instability can itself be complicated by recurrent instability, and when this occurs, this problem is difficult to treat. Some patients' THAs will continue to dislocate despite use of a constrained liner. One option in this difficult-to-treat group is conversion to a dual-mobility (DM) construct, but there are few data on this approach.
QUESTIONS/PURPOSES: (1) What were the Harris hip scores in a small group of patients whose constrained liners were converted to DM constructs to treat recurrent dislocation? (2) What were the redislocation, rerevision, and DM construct retention rates in these patients?
We conducted a retrospective analysis of a longitudinally maintained institutional database maintained by individuals other than the treating surgeons to identify patients undergoing conversion of constrained liners to DM constructs in revision THA from 2011 to 2014. We identified 16 patients who underwent revision of dislocated constrained liners to DM constructs. Two patients died before 2-year followup, leaving 14 patients available for followup at a minimum of 24 months and a median of 37 months (range, 24-71 months). Indications for conversion to DM constructs included patients with dislocation of multiple prior constrained liners, patients with at least partial abductor functioning and soft tissue tensioning, and patients at very high risk for recurrent instability as an alternative to resection arthroplasty. Ten patients (10 of 14) underwent DM conversion at the time of cup revision, whereas four patients (four of 14) had a DM construct cemented into a preexisting cup. Median age was 65 years (range, 53-93 years). Median number of prior hip surgeries was five (range, three to 10) and seven patients (seven of 14) had dislocated more than one constrained liner.
Harris hip score improved from a median of 57 (range, 55-67) to 84 (range, 68-96) postoperatively (p < 0.001). Three patients (three of 14) experienced a redislocation. Two (two of 14) of these patients were closed reduced and treated successfully nonoperatively; one (one of 14) patient experienced an intraprosthetic dislocation and underwent modular exchange. One patient (one of 14) underwent early resection arthroplasty for acetabular loosening after complex acetabular reconstruction. Overall, all other patients (13 of 14) retained a DM construct at final followup.
Conversion to a DM construct shows promise as a salvage option in high-risk, multiply operated on patients with dislocated constrained liners undergoing revision THA for recurrent instability. The ability to close reduce a dislocated DM construct is a distinct advantage over constrained liners. However, longer followup is required given that three of 14 redislocated, and one of those underwent revision for persistent instability at short-term followup.
Level IV, therapeutic study.
翻修全髋关节置换术（THA）治疗复发性不稳定本身可能因复发性不稳定而变得复杂，当这种情况发生时，这个问题很难治疗。尽管使用了限制性衬垫，一些患者的THA仍会继续脱位。对于这个难以治疗的群体，一种选择是转换为双动（DM）结构，但关于这种方法的数据很少。
问题/目的：（1）一小部分将限制性衬垫转换为DM结构以治疗复发性脱位的患者，其Harris髋关节评分是多少？（2）这些患者的再脱位、再次翻修和DM结构保留率是多少？
我们对一个由非治疗外科医生维护的纵向维护的机构数据库进行了回顾性分析，以确定2011年至2014年在翻修THA中接受限制性衬垫转换为DM结构的患者。我们确定了16例将脱位的限制性衬垫翻修为DM结构的患者。两名患者在2年随访前死亡，其余14例患者至少随访24个月，中位随访时间为37个月（范围24 - 71个月）。转换为DM结构的指征包括多个先前限制性衬垫脱位的患者、至少有部分外展肌功能和软组织张力的患者，以及作为切除性关节成形术替代方案的复发性不稳定高风险患者。10例患者（14例中的10例）在髋臼翻修时进行了DM转换，而4例患者（14例中的4例）将DM结构用骨水泥固定到现有的髋臼杯中。中位年龄为65岁（范围53 - 93岁）。先前髋关节手术的中位次数为5次（范围3 - 10次），7例患者（14例中的7例）脱位超过一个限制性衬垫。
术后Harris髋关节评分从中位57分（范围55 - 67分）提高到84分（范围68 - 96分）（p < 0.001）。3例患者（14例中的3例）出现再脱位。其中2例（14例中的2例）通过闭合复位并成功进行非手术治疗；1例患者（14例中的1例）发生假体内部脱位并接受了模块化置换。1例患者（14例中的1例）在复杂髋臼重建后因髋臼松动接受了早期切除性关节成形术。总体而言，所有其他患者（14例中的13例）在最终随访时保留了DM结构。
对于因复发性不稳定接受翻修THA且脱位的限制性衬垫的高风险、多次手术的患者，转换为DM结构作为一种挽救选择显示出前景。与限制性衬垫相比，闭合复位脱位的DM结构的能力是一个明显的优势。然而，鉴于14例中有3例发生再脱位，其中1例在短期随访时因持续不稳定接受了翻修，因此需要更长时间的随访。
IV级，治疗性研究。
