Dislocation of modern design rotating hinge total knee arthroplasty : case series and narrative review

Acta Orthop Belg. 2020 Jun;86(2):303-312.

Abstract

Knee dislocation is an infrequent complication after rotating hinge total knee arthroplasty (RHTKA). The aim of the present study was to describe our experience with dislocating RHTKA in a consecutive prospective large series, its occurrence rate, causative mechanisms and to perform a review of available literature. In total, six dislocations were observed in 303 RHTKA procedures (NexGen RHK, ZimmerBiomet, Warsaw, Indiana, US) at a mean of 10 (range, 2 - 24) months after surgery. This results in a 2% dislocation rate, which is lower than the 3.1% cumulative rate reported earlier in literature. Men and women were distributed equally, with a mean age of 56 years old. The indication for RHTKA among the six dislocations was revision in 4 cases and primary arthroplasty for the other 2 cases. Analysis revealed that the main mechanism of hinge dislocation was forced knee flexion with concomitant extensor mechanism insufficiency (4/6 cases). The second cause was unscrewing of the locking pin (2/6 cases). This is probably caused by the screw home mechanism that results in a counterclockwise torque -and therefore a loosening- effect on locking bolts, specifically in right-sided RHTKA. Obesity probably predisposes to hinge dislocation since 83% of patients in this series were obese (BMI, range 34 to 52). The findings of this study suggest that dislocation of RHTKA is a rare complication that could happen to obsese patients without an adequate extensor mechanism. Level of evidence : IV.

MeSH terms

  • Arthroplasty, Replacement, Knee* / adverse effects
  • Arthroplasty, Replacement, Knee* / instrumentation
  • Arthroplasty, Replacement, Knee* / methods
  • Biomechanical Phenomena / physiology*
  • Bone Nails
  • Bone Screws
  • Female
  • Humans
  • Knee Dislocation* / diagnosis
  • Knee Dislocation* / etiology
  • Knee Dislocation* / physiopathology
  • Knee Dislocation* / surgery
  • Knee Joint* / physiopathology
  • Knee Joint* / surgery
  • Knee Prosthesis
  • Male
  • Middle Aged
  • Obesity / epidemiology
  • Osteoarthritis, Knee / surgery*
  • Outcome and Process Assessment, Health Care
  • Postoperative Complications* / diagnosis
  • Postoperative Complications* / epidemiology
  • Postoperative Complications* / physiopathology
  • Postoperative Complications* / surgery
  • Prosthesis Design
  • Reoperation / methods
  • Risk Factors