title: In vivo testing of knee stability after rotating-hinge total knee arthroplasty: a comparison of 2 knee systems.
abstract: Rotating-hinge knee prostheses are used for reconstruction in cases of severe articular compromise and major bone loss. Biomechanical studies revealed that rotating-hinge designs with long and cylindrical pegs are more stable than devices with short and more tapered ones. Twenty-five patients underwent clinical examination using ultrasound, radiographs, and 3 different rating systems to examine the in vivo stability and functional outcome of 2 rotating-hinge knee systems. Overall, the study revealed that a stable reconstruction could be achieved with both tested devices, with good functional outcome. The results for medial and lateral lift-off during flexion and extension in ultrasonography were comparable, whereas the measured distraction of the Limb Preservation System (LPS/M.B.T.; DePuy, Warsaw, Indiana) was lower compared with the S-ROM Noiles prostheses (DePuy). The implant, the new formed capsule, and the remaining soft tissues have to maintain joint stability. Soft tissue reconstruction, especially the medial gastrocnemius flap, and the newly formed periprosthetic scar seems to prevent distraction of several millimeters. In addition, determining the lift-off with ultrasonography showed that the shape of the peg does not influence implant's stability against lateral directed forces.
authors.affiliation: Department of Orthopaedic Surgery, Medical University of Graz, Graz, Austria.
authors.forename: Joerg
authors.initials: J
authors.lastname: Friesenbichler
authors.forename: Mathias
authors.initials: M
authors.lastname: Glehr
authors.forename: Patrick
authors.initials: P
authors.lastname: Sadoghi
authors.forename: Werner
authors.initials: W
authors.lastname: Maurer-Ertl
authors.forename: Florian
authors.initials: F
authors.lastname: Ott
authors.forename: Andreas
authors.initials: A
authors.lastname: Leithner
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019544:Equipment Failure Analysis; D005260:Female; D006801:Humans; D007593:Joint Instability / Q000175:diagnosis* / Q000601:surgery*; D007719:Knee Joint / Q000601:surgery*; D007720:Knee Prosthesis; D008297:Male; D008875:Middle Aged; D011474:Prosthesis Design; D016059:Range of Motion, Articular; D020127:Recovery of Function; D016896:Treatment Outcome