APPROPRIATE TIBIAL TUNNEL ANGLE AND KNEE FLEXION ANGLE FOR AIMING FEMORAL INSERTION IN ENDOSCOPIC ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION.

Abstract

Abstract

Background Endoscopic ACL  reconstruction is the high technically demand orthopaedic procedure. Careful surgical techniques are necessary to avoid intraoperative complications. The endoscopic femoral aimer must be inserted via the tibial tunnel. If we do not place the knee in the appropriate position, the aimer will point to the incorrect position.

Objective To identify  the appropriate  tibial  tunnel  angle  (TTA)  and  knee  flexion  angle (KFA) and  the relationship between  these  two  angles.

Design Descriptive  study

Setting Gross  laboratory

Subjects Embalmed cadavers.

Materials &  Methods 104 cadaveric  knees of  54  cadavers  were  explored.  A 2.0 mm.  K-wire  was  drilled  to  the  ACL   tibial  footprint  with  different  TTA  40^o,55^o,70^o while changing  the  KFA to 60^o,75^o,90^o respectively.    Lateral   radiographic   imaging was done for every pair of  TTA  and KFA to evaluate whether K-wires pointed to the femoral wire loops.

A  K-wire was drilled to the ACL tibial footprint with TTA 40^o, and  the knee was flexed until the K- wire  pointed  to the femoral  wire  loop. Lateral radiographic imaging was done and the KFA was measured. These procedures were repeated again by changing TTA to 55^o and 70^o.

Results The  most appropriate TTA and KFA was TTA 55^o/ KFA 75^o which made the K-wires pointed  correctly 78.64%. The means of KFA when TTA  40^o, 55^oand 70^o were 98.85^o, 78.30^oand 56.39^o respectively. The relationship was presented in  the  following equation: KFA =  155.6-1.4 TTA, R² = 0.80.

Conclusion The  KFA at  55^o TTA is  not  equal  to  KFA at  TTA 40^o or 70^o.   We, therefore, propose the  reverse linear relationship  between KFA and  TTA  which may  guide  the  arthroscopist  to place the knee in less flexion  when using more TTA while  aiming  femoral tunnel and vice versa.