title: Two-Year Outcomes of a Randomized Trial Investigating a 6-Week Return to Full Weightbearing After Matrix-Induced Autologous Chondrocyte Implantation.
abstract: BACKGROUND
  Matrix-induced autologous chondrocyte implantation (MACI) has demonstrated encouraging outcomes in treating patients with knee cartilage defects. Postoperatively, the time required to attain full weightbearing (WB) remains conservative.
  
  
  OBJECTIVE
  We hypothesized that patients would have no significant clinical or radiological differences or graft complications after an 8-week or 6-week return to full WB after MACI.
  
  
  METHODS
  Randomized controlled trial; Level of evidence, 1.
  
  
  METHODS
  A total of 37 knees (n = 35 patients) were randomly allocated to either an 8-week return to full WB that we considered current best practice based on the existing literature (CR group; n = 19 knees) or an accelerated 6-week WB approach (AR group; n = 18 knees). Patients were evaluated preoperatively and at 1, 2, 3, 6, 12, and 24 months after surgery, using the Knee Injury and Osteoarthritis Outcome Score, 36-Item Short Form Health Survey, visual analog pain scale, 6-minute walk test, and active knee range of motion. Isokinetic dynamometry was used to assess peak knee extension and flexion strength and limb symmetry indices (LSIs) between the operated and nonoperated limbs. Magnetic resonance imaging (MRI) was undertaken to evaluate the quality and quantity of repair tissue as well as to calculate an MRI composite score.
  
  
  RESULTS
  Significant improvements ( P < .05) were observed in all subjective scores, active knee flexion and extension, 6-minute capacity, peak knee extensor torque in the operated limb, and knee extensor LSI, although no group differences existed. Although knee flexor LSIs were above 100% for both groups at 12 and 24 months after surgery, LSIs for knee extensor torque at 24 months were 93.7% and 87.5% for the AR and CR groups, respectively. The MRI composite score and pertinent graft parameters significantly improved over time ( P < .05), with some superior in the AR group at 24 months. All patients in the AR group (100%) demonstrated good to excellent infill at 24 months, compared with 83% of patients in the CR group. Two cases of graft failure were observed, both in the CR group. At 24 months, 83% of patients in the CR group and 88% in the AR group were satisfied with the results of their MACI surgery.
  
  
  CONCLUSIONS
  Patients in the AR group who reduced the length of time spent ambulating on crutches produced comparable outcomes up to 24 months, without compromising graft integrity.
authors.affiliation: School of Sport Science, Exercise and Health, University of Western Australia, Crawley, Australia.
authors.forename: Jay R
authors.initials: JR
authors.lastname: Ebert
authors.affiliation: School of Sport Science, Exercise and Health, University of Western Australia, Crawley, Australia.
authors.forename: Peter K
authors.initials: PK
authors.lastname: Edwards
authors.affiliation: Perth Radiological Clinic, Subiaco, Australia.
authors.forename: Michael
authors.initials: M
authors.lastname: Fallon
authors.affiliation: School of Sport Science, Exercise and Health, University of Western Australia, Crawley, Australia.
authors.forename: Timothy R
authors.initials: TR
authors.lastname: Ackland
authors.affiliation: Perth Orthopaedic and Sports Medicine Centre, West Perth, Australia.
authors.forename: Gregory C
authors.initials: GC
authors.lastname: Janes
authors.affiliation: School of Surgery (Orthopaedics), University of Western Australia, Crawley, Australia.
authors.forename: David J
authors.initials: DJ
authors.lastname: Wood
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002358:Cartilage, Articular / Q000000981:diagnostic imaging / Q000293:injuries* / Q000601:surgery*; D019902:Chondrocytes / Q000637:transplantation*; D005260:Female; D006801:Humans; D007718:Knee Injuries / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000534:rehabilitation* / Q000601:surgery*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D019637:Orthopedic Procedures / Q000379:methods; D010147:Pain Measurement; D016059:Range of Motion, Articular; D013997:Time Factors; D019415:Torque; D014182:Transplantation, Autologous; D016474:Weight-Bearing; D055815:Young Adult
keywords: gait; matrix-induced autologous chondrocyte implantation (MACI); rehabilitation; weightbearing