title: MR-guided focused ultrasound for the novel and innovative management of osteoarthritic knee pain.
abstract: BACKGROUND
  Severe knee pain associated with osteoarthritis (OA) is one of the most common and troublesome symptoms in the elderly. Recently, local bone denervation by MR-guided focused ultrasound (MRgFUS) has been demonstrated as a promising tool for pain palliation of bone metastases. The purpose of this study was to develop a novel treatment for knee OA using MRgFUS, and to validate its safety and efficacy.
  
  
  METHODS
  Eight patients with medial knee pain and eligible for total knee arthroplasty were included. MR-guided focused sonication treatments were applied to bone surface just below the rim osteophyte of medial tibia plateau with real-time monitoring of the temperature in the target sites. The pain intensity during walking was assessed on a 100 mm visual analog scale (VAS) before and after treatment. Pressure pain thresholds (PPTs) were also evaluated over several test sites adjacent to the sonication area and control sites one month after treatment.
  
  
  RESULTS
  Six patients (75%) showed immediate pain alleviation after treatment, and four of them demonstrated long-lasting effect at 6-month follow up (mean VAS reduction; 72.6%). In responders, PPTs in medial knee were significantly increased after treatment (Median; pre- 358 kpa vs post- 534 kpa, p < 0.0001). There were no adverse side effects or complications during and after treatment.
  
  
  CONCLUSIONS
  These initial results illustrate the safety and efficacy of the newly developing MRgFUS treatment. Significant increase of PPTs on treated area showed successful denervation effect on the nociceptive nerve terminals. MRgFUS is a promising and innovative procedure for noninvasive pain management of knee OA.
  
  
  BACKGROUND
  Trial Registration: UMIN000010193.
authors.affiliation: Department of Orthopaedic Surgery, Kochi Medical School, Kochi University, Oko-cho Kohasu, Nankoku 783-850, Japan. ikeuchim@kochi-u.ac.jp.
authors.forename: Masashi
authors.initials: M
authors.lastname: Izumi
authors.forename: Masahiko
authors.initials: M
authors.lastname: Ikeuchi
authors.forename: Motohiro
authors.initials: M
authors.lastname: Kawasaki
authors.forename: Takahiro
authors.initials: T
authors.lastname: Ushida
authors.forename: Kazuo
authors.initials: K
authors.lastname: Morio
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Namba
authors.forename: Thomas
authors.initials: T
authors.lastname: Graven-Nielsen
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Ogawa
authors.forename: Toshikazu
authors.initials: T
authors.lastname: Tani
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D018771:Arthralgia / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology / Q000628:therapy*; D005080:Exercise Test; D005260:Female; D006801:Humans; D053783:Magnetic Resonance Imaging, Interventional; D008297:Male; D020370:Osteoarthritis, Knee / Q000150:complications / Q000175:diagnosis / Q000503:physiopathology / Q000628:therapy*; D010147:Pain Measurement; D017288:Pain Threshold; D010865:Pilot Projects; D011446:Prospective Studies; D012720:Severity of Illness Index; D013997:Time Factors; D016896:Treatment Outcome; D014464:Ultrasonic Therapy / Q000009:adverse effects
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