Mechanical Comparison of Headless Screw Fixation and Locking Plate Fixation for Talar Neck Fractures

Locking vs. non-locking plate fixation in comminuted talar neck fractures: a biomechanical study using cadaveric specimens

BACKGROUND

Talar neck fractures are rare but potentially devastating injuries, with early reduction and rigid fixation essential to facilitate union and prevent avascular necrosis. Even small degrees of malunion will alter load transmission and subtalar joint kinematics. Changes in fixation techniques have led to dual plating strategies. While locked plating has perceived advantages in porotic bone and comminution, its biomechanical benefits in talar neck fractures have not been shown.

AIM

To compare the strength of locking vs. non-locking plate fixation in comminuted talar neck fractures.

METHOD

Seven pairs of cadaveric tali were randomised to locking or non-locking plate fixation. A standardised model of talar neck fracture with medial comminution was created, and fixation performed. The fixed specimens were mounted onto a motorised testing device, and an axial load applied.

RESULTS

Peak load to failure, deformation at failure, work done to achieve failure, and stiffness of the constructs were measured. No statistically significant difference was found between locking and non-locking constructs for all parameters.

CONCLUSIONS

Both constructs provide similar strength to failure in talar neck fracture fixations. Mean peak load to failure did not exceed the theoretical maximum forces generated of 1.1 kN when weight-bearing. We would advocate caution with early mobilisation in both fixations.

Biomechanical comparison of headless compression screws versus independent locking screw for intra-articular fractures

PURPOSE

Headless compression screws (HCS) have a variable thread pitch and headless design enabling them to embed below the articular surface and generate compression force for fracture healing without restricting movement. Locking screws have greater variety of dimensions and a threaded pitch mirroring the design of the HCS. The objective of this study is to determine whether locking screws can generate compression force and compare the compressive forces generated by HCS versus locking screws.

METHOD

A comparison between 3.5-mm HCS versus 3.5-mm locking screws and 2.8-mm HCS versus 2.7-mm locking screws was performed using a synthetic foam bone model (Synbone) and FlexiForce sensors to record the compression forces (N). The mean peak compression force was calculated from a sample of 3 screws for each screw type. Statistical analysis was performed using the one-way ANOVA test and statistical significance was determined to be p =  < 0.05.

RESULTS

The 3.5-mm Synthes and Smith and Nephew locking screws generated similar peak compression forces to the 3.5-mm Acutrak 2 headless compression screws with no statistically significant difference between them. The smaller 2.7-mm Synthes and Smith and Nephew locking screws initially generated similar compressive forces up to 1.5 and 2 revolutions, respectively, but their peak compression force was less compared to the 2.8-mm Micro Acutrak 2 HCS.

CONCLUSION

Locking screws are able to generate compressive forces and may be a viable alternative to headless compressive screws supporting their use for intra-articular fractures.

A comparative study of three different approaches in treatment of talar neck fractures

Purpose

The primary objective of this study was to observe and compare the radiographic and clinical outcomes among three different approaches which are anteromedial, anterolateral and combined approach in patients of talar neck fractures. The secondary objective was to observe various complications.

Material and method

A total of 30 patients underwent open reduction and internal fixation (ORIF) from September 2018 to march 2020 were selected retrospectively. 10 patients were there in each group. Talar neck fractures were classified according to Hawkins classification. All patients underwent ORIF with 4 mm Herbert screws. The follow-up examination included radiological evaluation, clinical and functional outcomes according to American Orthopaedic Foot and Ankle Society hind-foot score (AOFAS).

Results

30 patients were followed up for an average of 20.85 months (range 16-24). The mean time to bony union was 17.25 weeks, 17.35 weeks and 15.92 weeks in groups operated with anteromedial approach, anterolateral approach and combined approach respectively. The mean AOFAS hind-foot score was 76.34, 77.16 and 78.34 at 18th month follow-up in all three groups respectively. In each group, 1 patient had deep wound infection and 2 patients had superficial wound infection. Subtalar arthritis was the most common complication.

Conclusion

There is no significant difference between the three groups in terms of AOFAS hind-foot score, further combined approach provides better visualization of talus fractures and early bony union but it takes longer duration of surgery with increased post-operative complications in comparison with other two groups.

The role of cadaveric simulation in talus fracture research: A scoping review

BACKGROUND

Talus fractures are rare (<1% of all fractures), and their rarity limits the number of studies available to guide management. In instances such as this, cadaveric studies can play an important role. The purpose of this scoping review was to identify and describe the current body of literature on cadaveric studies of fractures of the talus.

METHODS

Through multiple electronic database searches (Medline, Embase, Scopus) we identified a broad body of cadaveric research into talus fractures, and these were classified into 4 main themes. Study characteristics were summarised along with any descriptive results and conclusions.

RESULTS

The search yielded 484 articles of which 19 met the inclusion criteria. They provide valuable insights into benefits and drawbacks of surgical approaches to the talus, particularly with regard to direct visualisation of anatomic reduction, and risks of neurovascular or tendon compromise. For talar neck fractures it is clear that cannulated screws offer superior fixation over plates, however, are inferior when considering anatomic reduction of the fracture. Direct visualisation of fracture reduction is far superior to intraoperative radiographic assessment, and mal-reduction leads to reduced subtalar joint range of motion, midfoot deformity, and increased joint contact pressures.

CONCLUSIONS

This study provides a summary of the existing literature surrounding the use of cadaver studies in fractures of the talus. We have identified gaps in the literature, particularly surrounding strength of fixation of new locking plate fixation techniques.

Union Rates of Talar Neck Fractures With Substantial Bone Defects Treated With Autograft

BACKGROUND

This study evaluated the union rate of talar neck fractures with substantial bone defects treated acutely with autologous tibial bone graft during primary osteosynthesis.

METHODS

A case series at a level 1 trauma center was performed to identify consecutive patients who underwent operative fixation of talar neck fracture with autograft (Current Procedural Terminology codes 28445 and 20902) between 2015 and 2018. "Substantial bone defect" was defined as a gap greater than 5 mm in the sagittal plane and greater than one-third of width of the talar neck in the coronal plane. Postoperative foot computed tomographic (CT) scans were obtained for all patients. Primary outcome was union, and secondary outcomes were malunion, avascular necrosis (AVN), post-traumatic arthritis (PTA), and patient-reported outcomes (PROs).

RESULTS

Twelve patients with 12 fractures were included in the series, with an average length of follow-up of 26 months (range: 7-55) The average age was 34 years (17-59), and the most common mechanism of injury was motor vehicle crash. The Hawkins classification of the fractures was 4 type II (2 type IIA and 2 type IIB) (33%) and 8 type III (67%). Four fractures (33%) were open fractures. Union was achieved in 11 patients (92%). There was 1 malunion (8%). AVN was identified on postoperative CT scans in 11 patients (92%). Three of these 11 eventually showed collapse. Ten patients (83%) had radiographic evidence of some degree of ankle PTA, and 12 patients (100%) had radiographic evidence of some degree of subtalar PTA. Average Patient-Reported Outcomes Measurement Information System-Short Form score was 37 (32-45) and average Foot and Ankle Ability Measure activities of daily living and sports subscale scores were, respectively, 61 (31-87) and 31 (0-71), respectively. Average visual analog scale score was 5 (0-10), and average Foot Function Index was 49 (7-89). SF-36 scores showed fair to poor outcomes in the majority of patients.

CONCLUSION

In this relatively small series, tibial autograft in primary osteosynthesis of comminuted talar neck fractures with substantial bone defects is associated with excellent union rates and low malunion rates. Despite high union rates, secondary outcomes of AVN with or without collapse, ankle and subtalar PTA, and relatively low PROs were common.

LEVEL OF EVIDENCE

Level IV, case series.

Talus Fractures: All I need to know

Talus fractures result following high energy trauma and can lead to significant functional impairment. The complex morphology of the talus, it's multiple articulations and tenuous blood supply translate into significant challenges that must be overcome to achieve the best possible outcomes. Despite advances made in their management, they continue to have high complication rates. Nonetheless, restoration of normal alignment will optimise outcomes. In this article, we report on the epidemiology, anatomy, classification, patient evaluation and current evidence for the management of talus fractures.

Talar fracture: Epidemiology, treatment and results in a multicenter series

INTRODUCTION

Talar fracture is rare. Treatment is surgical for neck and/or body fractures with displacement. The aims of the present study were to collect epidemiological data on talar fractures, and to assess the impact of trauma via various functional scores and radiographic impact in the medium term.

HYPOTHESIS

Displaced talar fracture shows negative medium-term functional and radiological/clinical impact.

MATERIAL AND METHODS

A multicenter retrospective study was performed with a minimum follow-up of 12 months post-trauma. Inclusion criteria included radiographic assessment at a minimum 12 months post-trauma and data on 3 functional scores: SF12, AOFAS and FAAM. 225 patients were initially included, 81 of whom had follow-up with functional and radiological/clinical assessment.

RESULTS

Fracture reduction was anatomic in 61% of cases when CT was performed; reduction quality was independent of approach (p>0.05). 45% of patients showed subtalar osteoarthritis at a mean 2 years, significantly related to reduction defect (p<0.05). Mean AOFAS score was acceptable, at 74/100. Factors for functional prognosis comprised: reduction quality, hindfoot alignment, subtalar osteoarthritis, and talar osteonecrosis with dome collapse.

DISCUSSION

Talar fracture led to late complications with socioeconomic impact. Subtalar osteoarthritis affects almost half of patients within some months of trauma. Optimal reduction is the key to fair progression. Postoperative CT assessment now seems mandatory.

LEVEL OF EVIDENCE

IV; multicenter retrospective study.

Talar Neck and Sustentaculum Fracture Fixation

SUMMARY

Talar neck fractures are uncommon fractures that result from high-energy trauma causing bony and soft tissue injury. When combined with sustentaculum fractures, care must be taken to plan the approach and fracture fixation strategy. We present a 57-year-old woman who experienced a motor vehicle accident, sustaining a Hawkins II talar neck fracture with associated sustentaculum tali fracture. We demonstrate the dual-incision approach to the talar neck with medial screw and lateral plate fixation. The sustentaculum fixation was accomplished with cannulated screws through a direct medial approach.

Fractures of the Talus: Current Concepts

Talus fractures continue to represent a challenging and commonly encountered group of injuries. Its near-complete articular cartilage surface, and its role in force transmission between the leg and foot, makes successful treatment of such injuries a mandatory prerequisite to regained function. Familiarity with the complex bony, vascular, and neurologic anatomy is crucial for understanding diagnostic findings, treatment indications, and surgical techniques to maximize the likelihood of anatomic bony union. This review details the structure and function of the talus, a proper diagnostic workup, the treatment algorithm, and post-treatment course in the management of talus fractures.

Biomechanical Comparison of Tension Band Fixation of Patella Transverse Fracture: Headless Screws Versus Headed Screws

OBJECTIVE

This study aimed to investigate the stability and strength of tension band wire fixation using headless compression screws versus headed screws for transverse patella fractures.

METHODS

Six matched pairs of fresh-frozen cadaveric knees with transverse osteotomies created at the midpoint of the patella were surgically fixed, with one knee randomly receiving fixation with headless screws (Acumed Acutrak 4/5) and the other with headed screws (Synthes 4.0 partially threaded cannulated screws). The specimens were mounted onto a servohydraulic load frame in a 45-degree flexed position and loaded through the quadriceps tendon. Interfragmentary movement was recorded with a motion analysis system. The initial fixation stiffness, range of interfragmentary motion, and strength of the headless screw construct were compared with the headed screw construct. Failure was defined as either a sudden drop in applied tendon force or 2 mm of separation on the anterior surface of the patella (ie, clinical failure), whichever occurred first.

RESULTS

Mean primary interfragmentary motion was 0.31 ± 0.28 degrees for the headed screws and 0.10 ± 0.06 degrees for headless screws under 150 N load (P = 0.03). Mean construct stiffness was 277 ± 243 N/degrees for the headed screws and 510 ± 362 N/degrees for the headless screws (P = 0.03). None of the constructs from either group displayed structural failure before reaching the clinical failure gap of 2 mm. The mean clinical failure strength was 808 ± 183 N for the headless screws construct and 520 ± 241 N for the headed screws construct (P = 0.03).

CONCLUSIONS

Headless screw tension band fixation demonstrated superior biomechanical behaviors over standard headed screw fixation with higher construct rigidity, smaller interfragmentary motion, and greater fixation strength.

Headless compression screw for horizontal medial malleolus fractures

BACKGROUND

Horizontal medial malleolus fractures are caused by the application of rotational force through the ankle joint in several orientations. Multiple techniques are available for the fixation of medial malleolar fractures.

METHODS

Horizontal medial malleolus osteotomies were performed in eighteen synthetic distal tibiae and randomized into two fixation groups: 1) two parallel unicortical cancellous screws or 2) two Acutrak 2 headless compression screws. Specimens were subjected to offset axial tension loading. Frontal plane interfragmentary motion was monitored.

FINDINGS

The headless compression group (1699 (SD 947) N/mm) had significantly greater proximal-distal stiffness than the unicortical group (668 (SD 298) N/mm), (P = 0.012). Similarly, the headless compression group (604 (SD 148) N/mm) had significantly greater medial-lateral stiffness than the unicortical group (281 (SD 152) N/mm), (P < 0.001). The force at 2 mm of lateral displacement was significantly greater in the headless compression group (955 (SD 79) N) compared to the unicortical group (679 (SD 198) N), (P = 0.003). At 2 mm of distal displacement, the mean force was higher in the headless compression group (1037 (SD 122) N) compared to the unicortical group (729 (SD 229) N), but the difference was not significant (P = 0.131).

INTERPRETATION

A headless compression screw construct was significantly stiffer in both the proximal-distal and medial-lateral directions, indicating greater resistance to both axial and shear loading. Additionally, they had significantly greater load at clinical failure based on lateral displacement. The low-profile design of the headless compression screw minimizes soft tissue irritation and reduces need for implant removal.

Talar Neck Fractures Treated Using a Highly Selective Incision: A Case-Control Study and Review of the Literature

We describe a highly selective incision combined with percutaneous manipulation for reduction and internal fixation of talar neck fractures. We retrospectively investigated the clinical data from 29 cases of talar neck fractures treated from January 2009 to June 2013. Fifteen patients (study group) were treated using a 1- to 2-cm limited incision placed on the anteromedial or anterolateral side of the talus, followed by percutaneous reduction and fixation. Another 14 patients (control group) underwent open reduction and internal fixation through a conventional anteromedial or anterolateral approach. All cases were fixed with Herbert screws or cannulated titanium screws. All the patients were followed up for a minimum of 18 (median 24) months. All the fractures displayed bony union at or before the final follow-up visit. The mean American Orthopaedic Foot and Ankle Society ankle scale score in the study group was 75.3 ± 17.7, 9 patients (60%) had good or excellent results, and 3 (20%) developed talar avascular necrosis. The mean ankle scale score in the control group was 78.9 ± 15.2, 9 patients (64.3%) had good to excellent results, and 6 (42.9%) developed avascular necrosis. No statistically significant differences were found in the American Orthopaedic Foot and Ankle Society score, the number of good to excellent outcomes, or the incidence of complications between the incision groups. A highly selective incision combined with percutaneous reduction and internal fixation can be used to treat fractures of the neck of the talus satisfactorily.