Hawkins Classification
Fractures of the neck of the talus
Hawkins LG · J Bone Joint Surg Am · 1970
Hawkins introduced a classification system for vertical talar neck fractures based on pattern of dislocation and demonstrated that higher degrees of adjacent joint displacement strongly correlate with an increased risk of avascular necrosis of the talar body. He also identified subchondral radiolucency on follow-up radiographs (Hawkins sign) as a reliable early indicator of intact vascularity and bone viability.
Citation & links
Hawkins LG. Fractures of the neck of the talus. J Bone Joint Surg Am. 1970 Jul;52(5):991-1002.
Key findings
- 1.Established a three-stage classification for vertical talar neck fractures: Type I (nondisplaced), Type II (displaced fracture with subtalar subluxation or dislocation), and Type III (displaced fracture with dislocation of both the subtalar and tibiotalar joints).
- 2.Avascular necrosis of the talar body directly correlated with increasing injury severity: 0% in Type I (0 of 6), 42% in Type II (10 of 24), and 91% in Type III (21 of 23).
- 3.Closed reduction proved successful in only a minority of displaced injuries and carried a substantial risk of residual malalignment, highlighting the need for accurate anatomical reduction.
- 4.First identified the 'Hawkins sign'—subchondral radiolucency of the talar dome visible on mortise or AP ankle radiographs between 6 to 8 weeks post-injury—reflecting osteoclastic resorption and indicating preserved blood supply.
- 5.Absence of subchondral radiolucency (persistence of relative subchondral sclerosis due to surrounding disuse osteopenia) indicated talar body osteonecrosis.
- 6.Post-traumatic subtalar and tibiotalar arthrosis were frequent long-term sequelae, particularly following displaced injuries or osteonecrosis with collapse.
Background
Prior to this publication, talar neck fractures were recognized as high-energy, potentially debilitating injuries, but their natural history, optimal surgical management, and predictors of avascular necrosis (AVN) remained poorly understood. Proposed interventions varied widely, ranging from nonoperative casting to primary arthrodesis or acute talectomy. Hawkins conducted this study to systematically categorize vertical fractures of the talar neck according to adjacent joint displacement, evaluate clinical and radiographic outcomes, and determine the incidence and prognostic factors of post-traumatic AVN.
Methods
Retrospective multicentre case series evaluating 57 vertical talar neck fractures in 55 patients treated across three clinical centres. Hawkins personally reviewed 43 patients and evaluated injury radiographs, treatment strategies (closed reduction versus open reduction with or without internal fixation), long-term complications, and plain radiographic features of talar revascularisation.
Clinical implications
The study established an enduring framework for risk-stratifying talar neck fractures and redefined management by demonstrating that anatomical reduction is paramount to minimize post-traumatic arthritis and re-establish joint congruency. It cautioned against non-anatomic closed reduction and provided surgeons with a practical radiographic tool ('Hawkins sign') to determine talar viability at 6 to 8 weeks, directly guiding postoperative weight-bearing protocols.
Critical appraisal
This paper represents a landmark descriptive series that provided the structural foundation for talus fracture classification and introduced an essential radiographic sign. However, limitations include its retrospective design, historical and non-standardized fixation modalities (such as Kirschner wires or smooth pins rather than modern rigid anatomical compression screws/plates), absence of CT imaging, single-observer classification without inter-/intra-observer reliability statistics, and lack of modern validated patient-reported outcome measures.
Teaching note
A core FRCS/EBOT topic: candidates must define Hawkins Types I–III (and note the 1978 Canale & Kelly addition of Type IV involving talonavicular dislocation) alongside their respective historical AVN rates (Type I: 0–10%, Type II: ~40%, Type III: ~90%, Type IV: up to 100%). Candidates must also accurately describe the pathophysiology and timing of the Hawkins sign: subchondral osteopenia seen at 6–8 weeks post-injury indicating revascularisation, which relies on intact blood flow causing resorption in disuse.
Exam-tested points
- ›Classification: Type I = nondisplaced neck fracture; Type II = subtalar subluxation/dislocation; Type III = subtalar and tibiotalar dislocation; Type IV (Canale & Kelly modification) = Type III plus talonavicular joint subluxation/dislocation.
- ›AVN incidence from the original series: Type I = 0% (modern literature quotes 0–10%); Type II = 42%; Type III = 91%.
- ›Hawkins sign: subchondral radiolucent band beneath the subchondral bone of the talar dome visible 6–8 weeks after injury on an AP/mortise ankle radiograph.
- ›Pathophysiology of Hawkins sign: active hyperaemic bone resorption in the setting of disuse osteopenia, which can only occur if microvascular perfusion is preserved (rules out AVN).
- ›Vascular anatomy of the talus: main supply is via the artery of the tarsal canal (branch of posterior tibial), deltoid branch (posterior tibial), artery of the sinus tarsi (peroneal and anterior tibial anastomoses), and anterior/posterior capsular branches.
- ›Emergency management of displaced talar neck fractures: urgent anatomical reduction to relieve skin tension and reduce compromise of remaining capsuloligamentous vascular pedicles.
- ›Canale view: specialized plain radiograph obtained with the foot in maximum equinus, 15 degrees pronation, and 75 degrees cephalad beam angle to visualize talar neck profile and varus malalignment.
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