title: A constrained device with increased range of motion prevents early dislocation.
abstract: Constrained components can treat or prevent instability after total hip arthroplasty. Some previous designs have shown a high rate of early dislocation. These early dislocations appear to be secondary to component impingement and levering out of the femoral head. We report the early rate of dislocation in 81 consecutive patients undergoing constrained total hip arthroplasty using a novel constrained device that allows substantially more range of motion and a higher lever out strength. One hip redislocated at 6 months followup, for a success rate of 98.8%. The success rate was 93% for patients for whom a constrained device was placed during revision for recurrent instability. This device allows a higher range of motion before prosthetic impingement and maintains a higher levering out strength when impingement occurs. These changes should provide long lasting hip stability in these difficult cases.
authors.affiliation: Joint Implant Surgeons, Inc., Columbus, OH, USA. BerendKR@joint-surgeons.com
authors.forename: Keith R
authors.initials: KR
authors.lastname: Berend
authors.forename: Adolph V
authors.initials: AV
authors.lastname: Lombardi
authors.forename: Michael
authors.initials: M
authors.lastname: Welch
authors.forename: Joanne B
authors.initials: JB
authors.lastname: Adams
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects* / Q000295:instrumentation*; D015331:Cohort Studies; D005260:Female; D006617:Hip Dislocation / Q000000981:diagnostic imaging / Q000209:etiology / Q000517:prevention & control*; D006622:Hip Prosthesis; D006801:Humans; D007593:Joint Instability / Q000000981:diagnostic imaging / Q000209:etiology / Q000517:prevention & control; D008875:Middle Aged; D011474:Prosthesis Design; D011475:Prosthesis Failure; D017755:Prosthesis Fitting; D011859:Radiography; D016059:Range of Motion, Articular / Q000502:physiology*; D020127:Recovery of Function; D012189:Retrospective Studies; D018570:Risk Assessment; D012680:Sensitivity and Specificity; D013997:Time Factors