title: Effect of a collateral ligament sparing surgical approach on mechanical properties of equine proximal interphalangeal joint arthrodesis constructs.
abstract: OBJECTIVE
  To (1) compare the effect of a collateral ligament sparing surgical approach with an open surgical approach on mechanical properties of proximal interphalangeal joint (PIPJ) arthrodesis, and (2) to determine the percentage of articular cartilage surface removed by transarticular (TA) drilling with different diameter drill bits.
  
  
  METHODS
  Randomized paired limb design.
  
  
  METHODS
  Cadaveric equine limbs (n=76).
  
  
  METHODS
  Cadaveric PIPJ were drilled using a 3.5, 4.5, or 5.5 mm drill bit at 80-84° to the dorsal plane to remove articular cartilage and subchondral bone from the distal articular surface of the proximal phalanx (P1) and the proximal articular surface of the middle phalanx (P2). Bone ends were photographed and the percentage of the projected surface area that was denuded of cartilage was measured. PIPJ arthrodesis constructs (3-hole dynamic compression plate [DCP], two 5.5 mm TA screws inserted in lag fashion, medial and lateral to the DCP; DCP-TA) were created using 2 surgical approaches in paired limbs. A conventional open approach was used in 1 limb and a collateral ligament sparing approach used in the other limb. Constructs were tested to failure in single-cycle 3-point dorsopalmar/plantar or lateromedial bending. Maximum load, yield load, and composite stiffness were compared between techniques.
  
  
  RESULTS
  The 3.5, 4.5, and 5.5 mm drill bits removed 24±4%, 35±5%, and 45±7% of total PIPJ articular cartilage surface, respectively. Constructs with the collateral ligament sparing approach had significantly greater mean yield load (11.3±2.8 versus 7.68±1.1 kN, P=.008) and mean maximum load (13.5±3.1 versus 10.1±1.94 kN, P=.02) under lateromedial bending. Under dorsopalmar/plantar bending there was no significant difference between surgical approaches. The collateral ligament sparing arthrodesis technique had a shorter surgical time (19±3 minutes) compared with the open technique (31±3 minutes).
  
  
  CONCLUSIONS
  A collateral ligament sparing surgical approach to the PIPJ with removal of articular cartilage by TA drilling and arthrodesis by DCP-TA was faster and stronger in mediolateral bending than arthrodesis constructs created with an open surgical approach.
  
  
  CONCLUSIONS
  Preservation of the collateral ligaments and TA drilling for cartilage removal during PIPJ arthrodesis may be a superior approach to the conventional open approach and warrants clinical evaluation.
authors.affiliation: Department of Clinical Sciences, Kansas State University, Manhattan, KS, USA. jbras@vet.ksu.edu
authors.forename: Jose J
authors.initials: JJ
authors.lastname: Bras
authors.forename: James D
authors.initials: JD
authors.lastname: Lillich
authors.forename: Warren L
authors.initials: WL
authors.lastname: Beard
authors.forename: David E
authors.initials: DE
authors.lastname: Anderson
authors.forename: Laura J
authors.initials: LJ
authors.lastname: Armbrust
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Frink
authors.forename: Kevin
authors.initials: K
authors.lastname: Lease
mesh_terms: D000818:Animals; D001174:Arthrodesis / Q000379:methods / Q000662:veterinary*; D001696:Biomechanical Phenomena; D002102:Cadaver; D017885:Collateral Ligaments / Q000601:surgery*; D005552:Forelimb; D006734:Horse Diseases / Q000601:surgery; D006736:Horses; D007592:Joint Diseases / Q000601:surgery / Q000662:veterinary; D014033:Toe Joint / Q000601:surgery