title: Area of Skin Numbness After Total Knee Arthroplasty: Does Minimally Invasive Approach Make Any Difference From Standard Approach?
abstract: Skin numbness after total knee arthroplasty (TKA) was reported in relation to injury of the infrapatellar branch of saphenous nerve (IPBSN).
  
  
  
  Phase I study: A nonrandomized and nonconsecutive selection of 30 patients undergoing unilateral TKA, using minimally invasive surgery approach, and 30 patients having standard approach were included. Area of skin numbness was periodically evaluated and compared until 1-year follow-up (FU). Phase II study: we dissected 15 normal cadaveric knees and followed the course and distribution of IPBSN.
  
  
  
  Twenty-nine predominantly female patients in each group completed 1-year FU with no differences in demographic data. Both the groups had significantly improved Knee Society Score clinical and function scores with no statistical differences. The numb areas in both the groups similarly decreased from 2 weeks (51.7 cm2vs 51.1 cm2) to 1 year (2.1 cm2vs 2.4 cm2) with similar percentages of no skin numbness at 1 year (69% vs 65%). The IPBSN branched from saphenous nerve before exiting the adductor canal and ran longitudinally and obliquely. It was found as a single nerve in 20%, a 2-branch nerve in 67% and a 3-branch nerve in 13%. All branches crossed the knee midline between superior patellar pole and tibial tubercle.
  
  
  
  Clinical study showed that TKA using minimally invasive surgery approach provided similar area of skin numbness to standard approach. Numbness area gradually decreased at serial FUs in both the groups. The cadaveric study demonstrated that the IPBSN consistently gave no branch passing the knee midline above superior patellar pole.
authors.affiliation: Faculty of Medicine, Department of Orthopaedics, Chulalongkorn University, Bangkok, Thailand.
authors.forename: Aree
authors.initials: A
authors.lastname: Tanavalee
authors.affiliation: Department of Orthopedic Surgery, Taksin Hospital, Bangkok, Thailand.
authors.forename: Arak
authors.initials: A
authors.lastname: Limtrakul
authors.affiliation: Department of Orthopedic Surgery, Ratchaburi Hospital, Ratchaburi, Thailand.
authors.forename: Pathomporn
authors.initials: P
authors.lastname: Veerasethsiri
authors.affiliation: Faculty of Medicine, Department of Orthopaedics, Chulalongkorn University, Bangkok, Thailand.
authors.forename: Chavarin
authors.initials: C
authors.lastname: Amarase
authors.affiliation: Faculty of Medicine, Department of Orthopaedics, Chulalongkorn University, Bangkok, Thailand.
authors.forename: Srihatach
authors.initials: S
authors.lastname: Ngarmukos
mesh_terms: D000368:Aged; D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects* / Q000379:methods / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D006987:Hypesthesia / Q000209:etiology*; D007717:Knee; D007719:Knee Joint / Q000294:innervation*; D008160:Lumbosacral Plexus; D008297:Male; D019060:Minimally Invasive Surgical Procedures / Q000009:adverse effects* / Q000706:statistics & numerical data; D010329:Patella / Q000294:innervation; D059348:Peripheral Nerve Injuries / Q000209:etiology*; D011446:Prospective Studies; D013848:Thigh; D013977:Tibia
keywords: MIS approach; TKA; minimally invasive surgery; skin numbness; total knee arthroplasty