Plecko Michael, Klein Karina, Planzer Katrin, Wähnert Dirk, Behm Pascal, Ferguson Stephen J, Brianza Stefano, Stadelmann Vincent A, von Rechenberg Brigitte
Trauma Hospital Graz (UKH), Goestinger Strasse 24, 8021, Graz, Austria.
Musculoskeletal Research Unit (MSRU), Vetsuisse Faculty, University of Zurich, Zurich, Switzerland.
BMC Musculoskelet Disord. 2020 Dec 3;21(1):806. doi: 10.1186/s12891-020-03781-6.
A new locking screw technology, named variable fixation, has been developed aiming at promoting bone callus formation providing initial rigid fixation followed by progressive fracture gap dynamisation. In this study, we compared bone callus formation in osteotomies stabilized with standard locking fixation against that of osteotomies stabilized with variable fixation in an established tibia ovine model.
A 3 mm tibial transverse osteotomy gap was stabilized in three groups of six female sheep each with a locking plate and either 1) standard fixation in both segments (group LS) or 2) variable fixation in the proximal and standard fixation in the distal bone segment (group VFLS) or 3) variable fixation in both segments (group VFLS). The implantation site and fracture healing were compared between groups by means of radiologic, micro tomographic, biomechanical, and histological investigations.
Compared to LS callus, VFLS callus was 40% larger and about 3% denser, while VFLS callus was 93% larger and its density about 7.2% lower. VFLS showed 65% and VFLS 163% larger amount of callus at the cis-cortex. There wasn't a significant difference in the amount of callus at the cis and trans-cortex in groups featuring variable fixation only. Investigated biomechanical variables were not significantly different among groups and histology showed comparable good healing in all groups. Tissues adjacent to the implants did not show any alteration of the normal structure in all groups.
Variable fixation promoted the formation of a larger amount of bone callus, equally distributed at the cis and trans cortices. The histological and biomechanical properties of the variable fixation callus were equivalent to those of the standard fixation callus. The magnitude of variable fixation had a biological effect on the formation of bone callus. At the implantation site, the usage of variable fixation did not raise additional concerns with respect to standard fixation. The formation of a larger amount of mature callus suggests that fractures treated with variable fixation might have a higher probability to bridge the fracture gap. The conditions where its usage can be most beneficial for patients needs to be clinically defined.
一种名为可变固定的新型锁定螺钉技术已被研发出来，旨在促进骨痂形成，提供初始的刚性固定，随后实现骨折间隙的渐进性动力化。在本研究中，我们在已建立的绵羊胫骨模型中，比较了采用标准锁定固定稳定截骨术与采用可变固定稳定截骨术的骨痂形成情况。
在三组中，每组六只雌性绵羊的3毫米胫骨横向截骨间隙用锁定钢板稳定，其中1）两段均采用标准固定（LS组），或2）近端采用可变固定，远端骨段采用标准固定（VFLS组），或3）两段均采用可变固定（VFLS组）。通过放射学、显微断层扫描、生物力学和组织学研究比较各组间的植入部位和骨折愈合情况。
与LS组骨痂相比，VFLS组骨痂大40%，密度高约3%，而VFLS组骨痂大93%，密度低约7.2%。VFLS组在顺皮质处的骨痂量多65%，VFLS组多163%。仅采用可变固定的组中，顺皮质和反皮质处的骨痂量无显著差异。各研究生物力学变量在组间无显著差异，组织学显示所有组的愈合情况均良好。植入物附近的组织在所有组中均未显示正常结构有任何改变。
可变固定促进了大量骨痂的形成，且在顺皮质和反皮质处分布均匀。可变固定骨痂的组织学和生物力学特性与标准固定骨痂相当。可变固定的程度对骨痂形成有生物学影响。在植入部位，与标准固定相比，使用可变固定不会引发更多问题。大量成熟骨痂的形成表明，采用可变固定治疗的骨折可能更有可能桥接骨折间隙。其使用对患者最有益的情况需要在临床上加以明确。
