Talar head fractures: An observational study of 33 talar head fractures derived from the Swedish Fracture Register

Background: Reports in the literature on talar head fractures are rare and limited to case reports and small case series. Questions/Purposes: This study aimed to describe a national cohort of talar head fractures for fracture characteristics, associated injuries, treatment, and reoperations. Methods: We reviewed all radiographs of patients enrolled in the SFR between 2011 and 2021 showing talar head fractures (AO/OTA 81-A3). We excluded those with talar head avulsion fractures, misclassified, multiple reg-istrations, or with a privacy notice in their medical records. The cohort was reviewed using medical records and radiographs at a minimum 2-year follow-up. Results: The study included 32 patients (33 fractures) ≥ 18 years of age. The median age was 32 (range 18 – 65) years, 84 % were men, and the main trauma mechanisms were motor vehicle accidents (28 %) and falls from heights (28 %) and graded as high-energy injuries in 50 % of the cases. 18 (55 %) were displaced and 15 (45 %) had comminuted fractures. 14 talar head fractures (42 %) had multiple injuries to the same foot. 21 patients (66 %) underwent surgical treatment, most commonly with screw fixation. Surgery was performed in 15 of 18 patients with displaced fractures. Four patients were reoperated, one with arthrodesis of the talonavicular joint and three for implant removal. No cases of avascular necrosis were identified. Conclusions: Talar head fractures are rare and occur mainly in men. They are associated with other foot injuries. Most talar head fractures are treated operatively. In this case series, we did not identify any case of avascular necrosis. Levels of Evidence: IV, retrospective observational cohort study

These fractures are caused by a compressive force through the sustentaculum of the calcaneus or an axial load through the navicular joint.Plantar flexion or dorsiflexion and inversion in combination with axial compression of the foot have been proposed as the mechanisms of injury that result in talar head fractures [17][18][19][20].This type of trauma produces mainly two fracture patterns: a crush injury to the articular surface with comminution or a noncomminuted two-part shear fracture [21].
Few studies have investigated the outcome of talar head fractures in adults.Therefore, this study describes the demographics, fracture characteristics, associated foot injuries, treatment, reoperations and complications of talar head fractures.

Study design and setting
This retrospective study was based on data from the Swedish Fracture Register (SFR) [22].The SFR, established in 2011, is a national quality register for managing fractures.
The register contains data on injury mechanisms, including low-or high-energy fracture classification and treatment (operative or nonoperative) of Swedish citizens with a fracture sustained in Sweden.
Detailed data on patient and fracture characteristics, injury mechanism, and fracture treatment are recorded in each affiliated department through a pre-specified digital form by the physician or orthopedic surgeon.Patients with a unique 12-digit personal identification number (PIN), given to all Swedish citizens at birth or after permanent immigration, are registered in SFR [23].The PIN includes the date of birth, and a 4-digit number first introduced in 1947 and modified to the present form in 1967.The PIN is the key for registration of patients in national registers, cross-linkage and identification of patients in medical records.
The proportion of departments affiliated with the SFR has increased gradually, from 40 % of orthopedic departments in January 2014 to full national coverage (54 of 54 departments) in January 2021.Compared to the Swedish National Patient Register, the completeness of registration of foot fractures was 56 % in 2022 [24].

Patients and data collection
We included patients ≥18 years of age with a talar head fracture with the International Statistical Classification of Diseases and Related Health Problems 10th Revision (ICD-10) codes S92.1/S92.10/11registered in the SFR between 2011 and 2021 (Fig. 1).All radiographs were first reviewed only to include clear talar head fractures and to exclude fractures erroneously classified.We reviewed only patients registered as talar head fractures and excluded those with small dorsal avulsion fragments of the talar head and misclassified fractures (Fig. 1).Patient were followed for a minimum of 2 years or until death.
Next, we used the unique PIN to collect data through a review of medical records and analysis of all contributing departments to verify and ensure the completeness of the data.

Data collection
Patient data from the SFR and review of the medical records included the following outcome variables: age, sex, type of trauma mechanism, injury cause, associated foot injuries, other injuries, fracture classification (81-A3.1 and 81-A3.2,Fig. 2), fracture displacement classified as displaced (>2 mm) and undisplaced, American Society of Anesthesiologists (ASA) classification, initial treatment, secondary surgery, and date of death.Reoperations were divided into implant removal, arthrodesis, re-osteosynthesis due to mechanical failure or surgical debridement due to deep postoperative infection (including antibiotics and implant retention).Missing data are presented in Table 1.

Statistics
Variables are presented as proportions of all fractures.Nominal variables are shown as proportions of all fractures and scale variables as median or means and range.We used SPSS (IBM SPSS Statistics for Mac, Version 28.0, Armonk, NY: IBM Corp. USA) for all statistical analyses.

Ethics
The study complied with the ethical principles of the Helsinki Declaration and was approved by the Swedish Ethical Review Authority (2022-04531-01-amendments 2023-00249-02, 2023-06071-02.

Patients and descriptive data
We identified 32 patients (33 fractures) classified as talar head fractures (81-A3) (Fig. 1).The most common exclusion reasons were avulsion or talar process fractures (n = 27, Fig. 1).32 patients (27 men) with a median age of 32 (range 21-65) years were included, and all were classified as ASA 1 or 2 (Table 1).The median time from injury to operatively treated fractures was 6 (range 0-72) days.The median follow-up was 76 (range 24-130) months.None of the patients died during the follow-up period.

Operative treatment and reoperations
Surgery was performed on 21 talar head fractures (64 %) (Table 3).Undisplaced fractures were operatively treated in 6 of 15 fractures (40 %, 5 with screws, 1 plate), and displaced fractures were treated operatively in 15 of 18 patients (83 %, 12 with screws, 2 pins, 1 primary arthrodesis).Of the comminuted fractures, 13 of 15 patients were treated operatively (11 with screws, 1 plate, 1 primary arthrodesis).The noncomminuted fractures were treated operatively in 8 of 18 fractures (44 %, 6 with screws, 2 pins).None of the patients treated non-operatively had later surgery during follow-up.Two patients with a comminuted and displaced fracture initially treated with screws were reoperated, one with arthrodesis of the talonavicular joint and one with extraction of screws.One patient with a comminuted and undisplaced fracture treated with plate fixation was reoperated with implant removal after fracture healing, and a further reoperation with the removal of osteophytes was performed later.One patient with a non-comminuted and displaced fracture treated with pins was reoperated with pin extraction after fracture healing.
Four patients had symptomatic posttraumatic osteoarthritis verified by x-ray in the talonavicular joint (two with associated subtalar  a A patient could have multiple injuries.
dislocation, one with a navicular, cuboideum, calcaneus, and cuneiform fracture, and one with an isolated talar head fracture).One of these patients was reoperated with arthrodesis.No cases of avascular necrosis were identified.

Discussion
Talar head fractures are rare, occurring mainly in men and associated with other foot injuries, and are often managed surgically.In this case series with at a minimum follow-up of 2 years, we found no cases of avascular necrosis, but posttraumatic osteoarthritis occur.
Talar head fractures have been reported to be associated with other lower extremity injuries in [4,[27][28].In the current study high-energy trauma was present in approximately half of the patients.Similar injuries have been described in the setting of high-or low-energy mechanisms [29].In our study, associated foot injuries were present in 42 % of patients, similar to a case series of eight operatively managed talar head fractures reported in the literature [10].
In contrast to Anderson et al., we found an approximately even distribution between comminuted and noncomminuted fractures [10].An explanation for the discrepancy could be that Anderson et al. included only operatively treated fractures, whereas our study comprised all talar head fracture types, regardless of treatment.
A large portion of the fractures were displaced and primarily managed operatively.The talonavicular joint is important for the medial column.Therefore, we believe reduction and fixation are indicated to possibly reconstruct this medial column to reduce the need for surgical intervention for subsequent posttraumatic osteoarthritis.
A treatment algorithm has been proposed in a systematic review published in 2015 [11].Undisplaced fractures are suggested to be treated with cast immobilization and non-weight bearing for 4 to 8 weeks.Displaced fractures with >50 % of talar head involvement or talonavicular joint instability should be considered for open reduction and fixation [11].For displaced fractures with <50 % of talar head involvement and a stable talonavicular joint excision of fracture fragments is an alternative.Surgery with screws, pins, and spanning plates has been described, and even primary fusion of the talonavicular joint is recommended for severe talar head or navicular comminution [10][11].
The main surgical approach in the current series was open reduction and screw fixation (only a few cases were treated with plate or pin fixation).One case was treated with primary talonavicular joint fusion.Notably, undisplaced fractures were also treated with fixation, albeit in a lower proportion than those with displaced fractures.
Our study identified a reoperation rate of 13 %.One patient had an arthrodesis of the talonavicular joint, and three underwent implant removal.
Large differences have been reported between talar head, body, and neck fractures in the risk of developing avascular necrosis [4,30].A recent study on the risk of avascular necrosis after talar fracture found an overall rate of 47 % for neck fractures and 26 % for talar body fractures [30].The head of the talus has a good blood supply, derived mainly from the anterior tibial artery by the tarsal sinus and lateral tarsal arteries [17,20].We did not identify any osteonecrosis during the study period, which concurs with reports that the vascular supply of the talar head provides an adequate healing condition [10,17,[31][32][33].The most common complication was symptomatic posttraumatic osteoarthritis, of which 3 of 4 patients had associated injuries along the Chopart joint, which could have contributed to this finding.Our findings are expected given the proximity to the talonavicular joint.
This study has two major limitations: the retrospective design and the small sample size, resulting in a descriptive presentation of our data.The short to midterm follow-up could mask long-term complications (e. g., symptomatic osteoarthritis and late development of osteonecrosis).
Because of a lack of coverage and completeness during the study period, not all talar head fractures are registered in the SFR.Furthermore, we were not able to identify talar head fractures not entered into the register or classified as other foot fractures.However, these limitations are counterbalanced by the study's strength in using a national quality register to identify the largest cohort of talar head fractures.The use of the unique PIN to collect data through a review of medical records to verify and ensure the completeness of the data is a strength of the present study and minimizes the missing data.
This case series provides data on demographics, fracture classification, potential treatment options, and prognosis regarding reoperations which is valuable for patient counseling.
In summary, talar head fractures are rare and occur mainly in men.Moreover, most of these fractures are associated with other foot injuries.In this case series, we found no cases of avascular necrosis but posttraumatic osteoarthritis could be a concern.

Declaration of Generative AI and AI-assisted technologies in the writing process
No generative AI and AI-assisted technologies were used in the present study or manuscript.special thanks to the valued colleagues around the country who assisted in collecting data and, not least, all participating patients.
* The value is given as median and range.†All values represent the number of patients and percent in parentheses.