title: A novel method for measuring medial compartment pressures within the knee joint in-vivo.
abstract: A novel method for the measurement of knee joint forces in-vivo is described. A thin (0.2mm) flexible electronic pressure sensor was inserted through a narrow arthroscopic portal into the osteoarthritic medial compartment of the knee joint. The sensor partially covered the load bearing area. The surgery was performed under local anaesthetic during normal arthroscopic examination following patient consent. Results are presented for 11 patients. The method was used in a pilot study to assess the effects of four valgus knee braces on medial compartment forces. An analysis of variance could not detect un-loading by any brace although there were large variations in force output. These variations may be attributable to shifts in the sensor position. In-vivo measurement of joint force is technically feasible.
authors.affiliation: Bioengineering Institute, University of Auckland, Floor 6, 70 Symonds Street, Auckland, New Zealand. i.anderson@auckland.az.nz
authors.forename: Iain A
authors.initials: IA
authors.lastname: Anderson
authors.forename: Andrew A
authors.initials: AA
authors.lastname: MacDiarmid
authors.forename: M
authors.initials: M
authors.lastname: Lance Harris
authors.forename: R
authors.initials: R
authors.lastname: Mark Gillies
authors.forename: Rhona
authors.initials: R
authors.lastname: Phelps
authors.forename: W R
authors.initials: WR
authors.lastname: Walsh
mesh_terms: D000704:Analysis of Variance; D001182:Arthroscopy; D001696:Biomechanical Phenomena; D001915:Braces; D004582:Electronics, Medical; D005240:Feasibility Studies; D006801:Humans; D007719:Knee Joint / Q000503:physiopathology* / Q000601:surgery; D009985:Orthopedics / Q000379:methods*; D010003:Osteoarthritis / Q000503:physiopathology* / Q000601:surgery / Q000628:therapy; D010865:Pilot Projects; D011312:Pressure; D019736:Prostheses and Implants