Morphological study of CT image of posterior pilon variant fracture and its possible clinical significance

Combined vertical and external rotational force in plantarflexion position produces posterior pilon fracture: A preliminary cadaveric study

BACKGROUND

Posterior pilon fracture is speculated to occur by a combination of rotation and axial load, which makes it different from rotational posterior malleolar fracture or pilon fracture, but is not validated in vitro. The aim of the current study is to investigate the injury mechanisms of posterior pilon fracture on cadaveric specimens.

METHODS

Eighteen cadaveric specimens were mounted to a loading device to undergo solitary vertical loading, solitary external rotational loading, and combined vertical and external rotational loading until failure, in initial position of plantarflexion with or without varus. The fracture characteristics were documented for each specimen.

RESULTS

Vertical loading force combined with external rotation force diversified the fracture types resulting in pilon fracture, tibial spiral fracture, rotational malleolar fracture, talar fracture or calcaneal fracture. Vertical violence combined with external rotational loading in position of 45° of plantarflexion and 0° of varus produced posterior pilon fracture in specimens No. 13 and 14.

CONCLUSION

Combination of vertical and external rotational force in plantarflexion position on cadaveric specimens produce posterior pilon fracture.

A systematic review of posterior pilon variant fractures

Posterior pilon variant ankle fractures (PPVF) are a unique subtype of posterior malleolar fractures which have been a source of controversy and confusion in recent years. There has not been a thorough literature review previously written on the topic. Database searches of PubMed and Embase were conducted from inception until June 2023. The key words included "pilon variant," "posterior pilon variant," and "posterior pilon" fractures. Outcomes were evaluated by union time, rates of delayed union, nonunion, malunion, and complication. A total of 15 articles relevant to surgical repair of pilon variant fractures were included in the literature review. The unique mechanism of injury has been reported to involve both rotational and axial forces, leading to involvement of the posterior and medial aspects of the distal tibia. Pilon variant fractures can be suspected by several characteristics on radiographs and have a high confirmation rate via CT images. Multiple systems have been proposed to classify this fracture pattern, but there is no consensus on the ideal classification system. Surgically, direct fixation has shown better short-term clinical outcomes versus indirect fixation or no fixation. PPVF have a distinct fracture pattern involving the posterior and medial columns of the distal tibial plafond, and results from a mechanism intermediate to rotational and axial forces. These fractures are more severe than tri-malleolar fractures due to increased rates of articular impaction and incongruity. Future classification systems should focus on joint surface area and the tibial pilon column involved to avoid confusion with less severe posterior malleolar fractures.

The treatment of a malunited posterior pilon fracture with talar dislocation: A staged surgical treatment protocol

BACKGROUND

Malunited posterior pilon fractures with talus dislocation (mPPFtd) are rare and there are no appropriate treatment strategies. The purpose of this study was to introduce a stepped strategy featuring preliminary soft tissue management according to the Ilizarov principle and delayed open reduction and internal fixation (ORIF) through a modified posteromedial approach to overcome rigid soft tissue contracture.

METHOD

From February 2015 to August 2021, 12 selected patients with mPPFtd who were treated with the staged protocol (Group A) were retrospectively analysed. The clinical and radiographic outcomes were evaluated using the American Orthopaedic Foot and Ankle Society (AOFAS) ankle-hindfoot score, the visual analogue scale (VAS) score, and the Burwell-Charnley score. Moreover, this case series was compared with some cases of fresh fracture (Group B) in patients that had the same baseline data from our previous study.

RESULTS

In Group A, the average length of time between the date of injury and the date of surgery was 4.8 ± 3.3 months. The average time to external fixator distraction, as the first-stage treatment, was 13.4 ± 1.0 days. In the second stage of ORIF, the posterosuperior dislocation of the talus was corrected with osteotomy and leverage manoeuvres. According to the Burwell-Charnley score system, the reduction quality was excellent in 9 cases and good in 3 cases. After a mean follow-up of 3.8 ± 2.1 years, there were no infections, wound healing problems, or nerve injuries in our cohort, and union was observed in all fractures without a loss of reduction. The baseline data of the two groups were not significantly different (p>0.05). The mean AOFAS score in Group A was 85.0 ± 10.5 and that in Group B was 95.4 ± 6.1 (p<0.05). The mean VAS score in Group A was 1.7 ± 1.4 and that in Group B was 0.7 ± 0.9 (p<0.05).

CONCLUSION

A staged surgical treatment strategy characterized by soft tissue management will improve the treatment of mPPFtd and produce satisfactory clinical outcomes.

LEVEL OF EVIDENCE

Level IV, retrospective case series.

Incidence and clinical results of tendinous injuries in calcaneus and pilon fractures

PURPOSE

The aims of this study were: (1) to define the incidence of tendinous injuries in calcaneus and pilon fractures with different fracture severity and (2) to determine the clinical impact of such injuries.

STUDY DESIGN AND METHODS

CT-scans of 121 patients with calcaneus and pilon fractures were retrospectively analyzed over a 4-year period. The tendinous injuries were identified and correlated with the type of fracture (location and classification). Clinical analysis was performed using the American Orthopedic Foot and Ankle Society (AOFAS) and SF-36 (Short Form-36 Health Survey) scores.

RESULTS

Tendinous injuries were observed in 36% of all CT-scans analyzed, with the most common injury being incarceration (n = 20) and dislocation (n = 24). Calcaneus fractures sanders type 3/4 were 9 times more prone to tendon injury (p < 0.001; OR 8.67; 95% CI 2.49-30.24). Pilon fractures Ruedi-Allgower type 2/3 were 8 times more prone to tendon injury (p = 0.005; OR 7.5; 95% CI 1.72-32.80). No significant differences (p > 0.05) were found in AOFAS and SF-36 scores between patients with/without tendon injuries for fractures with the same severity.

CONCLUSION

The incidence of tendon injuries in calcaneus/pilon fractures is high and may be underreported. Calcaneus fractures are prone to peroneal tendon injury. In pilon fractures, it is important to look for tibialis posterior tendon injury, especially entrapment. The presence of tendinous injuries does not affect function and pain for the same type of calcaneus and pilon fractures at the long term.

LEVEL OF EVIDENCE

Level 3 retrospective study.

Early outcomes of a novel bicruciate-retaining knee system: a 2-year minimum retrospective cohort study

INTRODUCTION

Bicruciate retaining (BCR) total knee arthroplasty (TKA) was designed to simulate natural knee kinematics and improve proprioception by retaining both the ACL and PCL. While the prospect of the design appears favorable to patients, previous designs have demonstrated modest survivorship rates compared to traditional designs. This study aims to report the early functional outcomes and implant survivorship of a novel BCR design.

MATERIALS AND METHODS

A multi-center, retrospective study was conducted identifying BCR TKA patients from 2016 to 2017. Patient demographics, quality outcomes, and post-operative complications were collected. A Kaplan-Meier analysis was used to evaluate revision-free survival.

RESULTS

One-hundred thirty-three patients with a mean follow-up time of 2.35 ± 0.25 years (range: 2.00-2.87 years) were identified. Patients receiving BCR TKA were, on average, 61.46 ± 9.27 years-old, obese (BMI = 31.80 ± 6.01 kg/m²), predominantly white (71.4%), and female (69.9%). The device was most often implanted using standard instruments (85.7%) compared to computer-assisted navigation (13.5%). Average length-of-stay was 1.77 ± 0.97 days. Six patients had a reoperation; three (2.5%) full revisions occurred for: infection (n = 1), arthrofibrosis (n = 1), and ACL rupture (n = 1); one (0.8%) tibial revision occurred for: arthrofibrosis; two (1.5%) liner exchanges occurred for: infection (n = 1) and arthrofibrosis (n = 1). Kaplan-Meier survivorship analysis of cumulative failure at 2-year showed a survival rate of 96.2% (95% confidence interval, 91.2-98.4%) for all-cause reoperation, 97.3% (91.6-99.1%) for aseptic revision, and 100% for mechanical failure.

CONCLUSION

Survivorship was 96.2% for all-cause reoperation, 97.3% for aseptic revision, and 100% for mechanical implant failure at 2-years. This novel BCR TKA demonstrated no implant-related complications and excellent survivorship outcomes over 2 years with comparable revision rates to those previously reported in the literature.

Computed tomography-based classifications of posterior malleolar fractures and their inter- and intraobserver reliability: a comparison of the Haraguchi, Bartoníček/Rammelt, and Mason classifications

INTRODUCTION

Complex ankle fractures often include fractures of the posterior malleolus. The most clinically relevant posterior malleolus fracture classifications are computed tomography (CT) based. These classifications aim to enable clear communication and help develop treatment strategies. This study investigates the inter- and intraobserver reliability of the Haraguchi, Bartoníček/Rammelt and Mason posterior malleolar fracture classifications.

MATERIALS AND METHODS

CT scans of 113 patients with a mean age of 56.2 (SD ± 17.8) years and fractures involving the posterior malleolus were analyzed twice by 4 observers with different levels of training. The posterior malleolar fractures were classified according to Haraguchi et al., Bartoníček/Rammelt et al. and Mason et al. The intraobserver and interobserver reliabilities were determined by calculating Cohen's and Fleiss' kappa values.

RESULTS

We found substantial multi-rater interobserver agreement for all three classifications. The Haraguchi classification 0.799 (CI 0.744-0.855) showed the highest agreement, followed by the Bartoníček/Rammelt 0.744 (0.695-0.793) and Mason 0.717 (CI 0.666-0.768) classifications. Subgroup analyses showed substantial to perfect agreement for the Haraguchi and substantial agreement for the Bartoníček/Rammelt and Mason classifications independent of observer expertise. The intraobserver reliability was perfect for three and substantial for one of the observers. However, the classifications have certain pitfalls and do not consider the number of fragments, articular surface impressions, or intercalary fragments.

CONCLUSION

All classifications show substantial, if not perfect inter- and intraobserver reliabilities independent of observer level of expertise.