title: Influence of skin incision position on physiological and biochemical changes in tissue after primary total knee replacement - a prospective randomised controlled trial.
abstract: BACKGROUND
  Influence of skin incision position on physiological and biochemical changes in tissue after primary total knee replacement. A prospective randomised controlled trial. The blood supply to the skin covering the anterior knee has been shown to arise predominantly from blood vessels on the medial side of the knee. Skin incisions for primary Total Knee Replacement (TKR) positioned medially therefore risk creating a large lateral skin flap that may be poorly perfused. Poorly perfused skin is likely to result in hypoxia at the wound edges and consequently may lead to delayed wound healing and complications.
  
  
  METHODS
  We have carried out a randomised controlled trial (n = 20) to compare blood flow on both the medial and lateral sides of two commonly used skin incisions in TKR (midline and paramedian). We have also assessed interstitial biochemistry (glucose, pyruvate and lactate levels) in the presumed at risk lateral skin flap of both incision types.
  
  
  RESULTS
  In both incision types tissue hyper-perfusion occurs post-operatively and is maintained for at least 3 days. We found no significant difference between blood flow between the two incision types on the medial side of the incision at either day 1 (p = 0.885) or day 3 post-op (p = 0.269), or, on the lateral side of the incision (p = 0.885 at day 1, p = 0.532 at day 3). Glucose levels are maintained post-operatively in the at risk lateral flap with only minimal changes. Lactate levels rise post-operatively and remain elevated for at least 24 hours. However, the levels did not reach levels suggestive of critical ischaemia in either incision group and no significant difference was observed between incision types.
  
  
  CONCLUSIONS
  We conclude that the use of a paramedian incision results in only minimal biochemical changes, which are unlikely to alter wound healing.
  
  
  BACKGROUND
  ISRCTN06592799 .
authors.affiliation: Orthopaedic Research Unit, Glasgow Royal Infirmary, Gatehouse Building, 84 Castle St, Glasgow, G4 OSF, UK.
authors.forename: David Q
authors.initials: DQ
authors.lastname: Donaldson
authors.affiliation: Orthopaedic Research Unit, Glasgow Royal Infirmary, Gatehouse Building, 84 Castle St, Glasgow, G4 OSF, UK.
authors.forename: Matthew
authors.initials: M
authors.lastname: Torkington
authors.affiliation: Orthopaedic Research Unit, Glasgow Royal Infirmary, Gatehouse Building, 84 Castle St, Glasgow, G4 OSF, UK.
authors.forename: Iain C
authors.initials: IC
authors.lastname: Anthony
authors.affiliation: Orthopaedic Research Unit, Glasgow Royal Infirmary, Gatehouse Building, 84 Castle St, Glasgow, G4 OSF, UK.
authors.forename: Eugene F
authors.initials: EF
authors.lastname: Wheelwright
authors.affiliation: Orthopaedic Research Unit, Glasgow Royal Infirmary, Gatehouse Building, 84 Castle St, Glasgow, G4 OSF, UK. Mark.blyth@ggc.scot.nhs.uk.
authors.forename: Mark Jg
authors.initials: MJ
authors.lastname: Blyth
authors.affiliation: Orthopaedic Research Unit, Glasgow Royal Infirmary, Gatehouse Building, 84 Castle St, Glasgow, G4 OSF, UK.
authors.forename: Bryn G
authors.initials: BG
authors.lastname: Jones
mesh_terms: D000368:Aged; D019645:Arthroplasty, Replacement, Knee / Q000379:methods*; D062109:Dermatologic Surgical Procedures / Q000379:methods*; D045604:Extracellular Fluid; D005260:Female; D005947:Glucose / Q000378:metabolism; D006801:Humans; D019344:Lactic Acid / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000378:metabolism / Q000503:physiopathology / Q000601:surgery*; D011446:Prospective Studies; D019289:Pyruvic Acid / Q000378:metabolism; D012039:Regional Blood Flow / Q000502:physiology; D012867:Skin / Q000098:blood supply; D013524:Surgical Flaps; D014945:Wound Healing / Q000502:physiology
chemical_list: D019344:Lactic Acid; D019289:Pyruvic Acid; D005947:Glucose