Khalid Mohamed, Theivendran Kanthan, Cheema Mubashir, Rajaratnam Vaikunthan, Deshmukh Subodh C
Birmingham Hand Centre, University Hospital Birmingham, Selly Oak Hospital, Birmingham, UK.
Clin Biomech (Bristol). 2008 Nov;23(9):1136-40. doi: 10.1016/j.clinbiomech.2008.06.005. Epub 2008 Jul 22.
Bicortical fixation of proximal phalangeal fractures may damage underlying flexor tendons secondary to drilling and screw protrusion in the dorsal-ventral direction. The aim of this study was to measure and compare the pull-out force of unicortical screws compared to bicortical screws in human cadaveric proximal phalanges to identify optimal configuration for internal fixation.
Forty proximal phalanges were harvested. Bicortical and unicortical self tapping 1.7mm screws were inserted into paired phalanges at the distal and proximal metaphysis and at the mid-diaphysis placed in the dorso-ventral direction. Pull-out force of unicortical and bicortical screws were measured and compared.
Bicortical screw pull-out force is significantly higher than that of unicortical screws in the dorsal-ventral direction. Pull-out strength of unicortical screws at the mid-diaphysis was significantly higher than the pull-out strength of bicortical screws at the proximal metaphysis (181.8N versus 31.5N, P<0.0001).
Diaphyseal fixation is stronger than metaphyseal for both unicortical and bicortical configurations. Unicortical mid-diaphyseal is stronger than bicortical proximal metaphyseal screw pull-out strength. This study provides biomechanical data that may be helpful for individualizing fracture fixation techniques at the proximal phalanx.
近节指骨骨折的双皮质固定可能会因钻孔和螺钉在背腹方向的突出而损伤深层的屈肌腱。本研究的目的是测量并比较单皮质螺钉与双皮质螺钉在人体尸体近节指骨中的拔出力，以确定内固定的最佳构型。
采集40根近节指骨。将双皮质和单皮质自攻1.7毫米螺钉以背腹方向插入成对指骨的远端和近端干骺端以及骨干中部。测量并比较单皮质和双皮质螺钉的拔出力。
在背腹方向上，双皮质螺钉的拔出力显著高于单皮质螺钉。骨干中部单皮质螺钉的拔出强度显著高于近端干骺端双皮质螺钉的拔出强度（181.8牛对31.5牛，P<0.0001）。
对于单皮质和双皮质构型，骨干固定均强于干骺端固定。骨干中部单皮质螺钉的拔出强度强于近端干骺端双皮质螺钉。本研究提供的生物力学数据可能有助于近节指骨骨折固定技术的个体化。
