title: The effect of tibial component sizing on patient reported outcome measures following uncemented total knee replacement.
abstract: When performing total knee replacement (TKR), surgeons are required to decide on the most appropriate size of tibial component. As implants are predominantly selected from incremental sizes of a preferred design, it may be necessary for a surgeon to slightly under or oversize the component. There are concerns that overhang could lead to pain from irritation of soft tissues, and an undersized component could lead to subsidence and failure. Patient reported outcome measures were recorded in 154 TKRs at one year postoperatively (in 100 TKRs) and five years post-operatively (in 54 TKRs) in 138 patients. The Oxford Knee Score (OKS), WOMAC and SF-12 were recorded, and a composite pain score was derived from the OKS and WOMAC pain questions. Tibial component size and position were assessed on scaled radiographs and implants were grouped into anatomic sized tibial component (78 TKRs), undersized component (48 TKRs), minor overhang one to three mm (10 TKRs) or major overhang ≥ 3 mm (18 TKRs). There was no statistically significant difference between the mean post-operative OKS, WOMAC, SF-12 or composite pain score of each group. Furthermore, localisation of the site of pain did not correlate with medial or lateral overhang of the tibial component. Our results suggest that tibial component overhang or undersizing is not detrimental to outcome measures or pain.
  
  
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authors.affiliation: Department of Orthopaedics, Southern General Hospital, 1345 Govan Road, Glasgow G51 4TF, United Kingdom. Electronic address: simon.abram@doctors.org.uk.
authors.forename: Simon G F
authors.initials: SG
authors.lastname: Abram
authors.affiliation: Department of Orthopaedics, Southern General Hospital, 1345 Govan Road, Glasgow G51 4TF, United Kingdom.
authors.forename: Andrew G
authors.initials: AG
authors.lastname: Marsh
authors.affiliation: Department of Orthopaedics, Southern General Hospital, 1345 Govan Road, Glasgow G51 4TF, United Kingdom.
authors.forename: Alistair S
authors.initials: AS
authors.lastname: Brydone
authors.affiliation: Department of Orthopaedics, Southern General Hospital, 1345 Govan Road, Glasgow G51 4TF, United Kingdom.
authors.forename: Fiona
authors.initials: F
authors.lastname: Nicol
authors.affiliation: Department of Orthopaedics, Southern General Hospital, 1345 Govan Road, Glasgow G51 4TF, United Kingdom.
authors.forename: Aslam
authors.initials: A
authors.lastname: Mohammed
authors.affiliation: Department of Orthopaedics, Southern General Hospital, 1345 Govan Road, Glasgow G51 4TF, United Kingdom.
authors.forename: Simon J
authors.initials: SJ
authors.lastname: Spencer
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects / Q000295:instrumentation*; D002484:Cementation; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007720:Knee Prosthesis / Q000009:adverse effects*; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000601:surgery*; D010149:Postoperative Pain / Q000209:etiology*; D063868:Patient Outcome Assessment; D017060:Patient Satisfaction; D011446:Prospective Studies; D017755:Prosthesis Fitting / Q000009:adverse effects*; D013997:Time Factors
keywords: Arthroplasty; Knee; Outcome; Pain; Replacement