Myatt Darren, Stringer Howard, Chapman James, Fischer Ben E, Mason Lyndon
Trauma and Orthopaedic Department, Liverpool University Hospitals NHS Foundation Trust, Liverpool, UK.
University of Liverpool, Liverpool, UK.
Bone Jt Open. 2025 Apr 17;6(4):446-453. doi: 10.1302/2633-1462.64.BJO-2024-0132.R1.
Occult posterior malleolar fractures (PMFs) associated with tibial shaft fractures are thought to occur most commonly in spiral fracture types of the tibia. We hypothesize that tibial diaphyseal fracture patterns would be associated with certain PMFs, highlighting the pathomechanics of the injury.
A retrospective review was performed on data collected between 1 January 2013 and 9 November 2020. The inclusion criteria were patients aged over 16 years with a diaphyseal tibial fracture who had undergone a CT of the affected lower limb. The Mason and Molloy posterior malleolar fracture classification system was used to describe the morphology of the PMFs.
There were 764 diaphyseal fractures identified. Of these, 442 met the inclusion criteria. A total of 107patients (24.21%) had PMF extensions. The classification of the PMFs according to Mason and Molloy revealed eight type 1 fractures (7.48%), 60 type 2A (56.07%), six type 2B (5.61%), and 33 type 3 fractures (30.84%). The most common PMF seen in this study was the minor rotational pilon (type 2A). PMFs generally occur in combination with spiral diaphyseal fractures (42A1, 42B1, 42C1, and 43A1). The majority of PMFs were undisplaced pre-surgical intervention. Only the 2B subtype (major rotational pilon) had a significant association with fracture displacement.
This study highlighted an association between spiral tibial shaft fractures and type 2A posterior malleolus fractures. Unlike the PM fractures of the ankle, the majority of PM fractures associated with tibia fractures are undisplaced. We theorize that unlike the force transmission in ankle fractures, where the rotational force is in the axial plane in a distal-proximal direction, in the PM fractures related to tibia fractures, the rotational force in the axial plane progresses from proximal-distal. Therefore, the force transmission which exits posteriorly, finally dissipates the force and is thus unlikely to displace.
与胫骨干骨折相关的隐匿性后踝骨折（PMF）被认为最常发生于胫骨的螺旋骨折类型中。我们假设胫骨干骨折模式会与特定的PMF相关，从而突出损伤的病理力学机制。
对2013年1月1日至2020年11月9日期间收集的数据进行回顾性分析。纳入标准为年龄超过16岁、患有胫骨干骨折且接受过患侧下肢CT检查的患者。采用梅森（Mason）和莫洛伊（Molloy）后踝骨折分类系统描述PMF的形态。
共识别出764例胫骨干骨折。其中，442例符合纳入标准。共有107例患者（24.21%）存在PMF延伸。根据梅森和莫洛伊分类系统，PMF的分类显示8例1型骨折（7.48%）、60例2A型骨折（56.07%）、6例2B型骨折（5.61%）和33例3型骨折（30.84%）。本研究中最常见的PMF是轻微旋转型pilon骨折（2A型）。PMF通常与螺旋形胫骨干骨折（42A1、42B1、42C1和43A1）合并发生。大多数PMF在手术干预前无移位。只有2B亚型（主要旋转型pilon骨折）与骨折移位有显著相关性。
本研究突出了螺旋形胫骨干骨折与2A型后踝骨折之间的关联。与踝关节的后踝骨折不同，与胫骨骨折相关的大多数后踝骨折无移位。我们推测，与踝关节骨折中旋转力沿轴向平面由远至近的力传递方式不同，在与胫骨骨折相关的后踝骨折中，轴向平面的旋转力由近至远。因此，向后传出的力最终消散，从而不太可能导致移位。
