Medical Legal cases: Ankle fractures

Ankle fractures

Ankle anatomy

The ankle joint is composed of 3 bones:

• The tibia (shin bone)
• The fibula
• The talus

The inner (medial) side of the ankle is part of the tibia, and the outer (lateral) part is formed by the tip of the fibula. These both articulate with the talus, forming the ankle joint.

The ankle joint is held together by ligaments connecting the tibia and fibula to the talus, calcaneus (heel bone found under the talus) and navicular (bone in the midfoot).

The deltoid ligament is found on the medial side of the joint, and is attached at the medial malleolus of the tibia and connects to the calcaneus, the navicular and to the talus.

The anterior and posterior talofibular ligaments on the lateral side of the joint connect the lateral malleolus of the fibula to the talus.

The calcaneofibular ligament is attached at the lateral malleolus and to the calcaneus.

The ankle joint allows plantarflexion and dorsiflexion. Inversion and eversion (rolling inward and outward) occur at the subtalar joint.

Types of ankle fractures

Ankle fracture refers to breaks of the distal ends of the tibia and fibula called the malleoli. Fractures may involve either one side or both sides (bimalleolar fracture) and sometimes also involve the back of the tibia (posterior malleolus).

Fractures can be classified according to the site and number of malleoli involved:

• Isolated medial malleolus fracture
• Isolated lateral malleolus fracture
• Bimalleolar fracture (medial and lateral)
• Trimalleolar fracture

 Another common way of classifying ankle fractures is the Weber System. This is based on the level of the fracture of the fibula. Just above the ankle joint, there is a strong band of tissue called the 'syndesmosis' which joins the tibia and the fibula and is a key stabilising feature of the ankle joint.

Weber A fracture involves a break in the fibula below the syndesmosis. As the syndesmosis is intact, the fibula and tibia are stabilised against each other.

Weber B fracture involves a break at the level of the ankle joint and syndesmosis. The latter may be partially torn and the fracture may displace thus destabilising the ankle joint. The medial malleolus may be fractured or the deltoid ligament may be torn.

Weber C fracture involved a break above the level of the syndesmosis, with the disruption of the syndesmosis. This causes a widening between the tibia and fibula. Medial malleolus fracture and injury to the deltoid ligament is usually present.

 How does the injury occur?

Ankle fractures can occur as a result of high-energy trauma, e.g. falls from heights, road traffic collisions and sports injuries.

In the elderly population with osteoporosis, low-energy fractures occur as a result of small forces on weak bones. And simple trip and twisting of the ankle can result in a fracture.

 How is the injury diagnosed?

Patients present with pain, swelling and inability to weight bear. Displaced fractures or dislocations cause deformity of the joint and this may also affect the circulation and nervous supply to the foot. High-energy injuries can result in open fractures.

Radiographs of the ankle should include a mortise view to visualise the ankle joint space and a lateral view.

CT scan may sometimes be required in complex fractures involving the talus or tibial plafond.

MRI scan may be needed in outpatient management to assess ligamentous injuries.

 What are the management options?

Treatment depends on the type and severity of the fracture. Simple stable fractures with no displacement or talar shift are generally treated non-operatively. Initally a backslab plaster is applied in the emergency department and this is later either completed to a full cast or changed to a full cast once the swelling subsides. This is usually done on follow-up in the fracture clinic.

Sometimes closed manipulation is required before application of plaster. This is the case for displaced fractures or dislocations.

In cases of fractures with minimal talar shift, closed manipulation and application of plaster may be the definitive treatment, whereas in cases of dislocations, this is merely the first stage before surgery.

Surgical treatment is needed if the fracture is unstable or displaced. This involved open reduction of the fracture and internal fixation with plate and screws.

When there is significant injury to the soft tissues around the ankle joint causing swelling, this must be allowed to subside before surgery can be carried out. The leg is elevated and ice-packs used to help relieve the swelling.

If the fracture is very unstable such that it cannot be held reduced in a backslab plaster to allow the swelling to subside prior to definitive surgery, staged surgery may be indicated. This involved the application of a temporary external fixator before definitive internal fixation. An external fixator is also indicated in certain cases of open fractures. This can also be used as a definitive form of fixation.

 What are the restrictions associated with the injury?

Patients can be allowed to weight bear in a walking cast in cases of stable undisplaced fractures. For all other cases, they need to remain non-weight bearing on the affected side for about 6 weeks, and have to use crutches or a Zimmer frame.

Some elderly patients may not be able to manage weight-bearing on only one leg and may need a wheelchair and help transferring.

Depending on the mode of treatment, patients need repeat radiographs usually at 1, 2 and 6 weeks to check the position of the fracture and assessment of healing.

Weight bearing, either full or protected using crutches, is usually started at 6 weeks.

Some patients may need physiotherapy once they start mobilising to regain their range of movement and normal strength.

 What are the long-term issues with the injury?

Post-traumatic arthritis is rare if the fracture is treated by anatomic reduction and fixation.

Wound problems occur in 4–5 % of patients who undergo surgical management.

Deep infections are rare (1–2 %), but the risk increases significantly (20%) in diabetic patients.

Complex open fractures with soft tissue damage have a worse prognosis than isolated closed ankle fractures.

Further surgery may be required for removal of metalwork if it becomes prominent or problematic.

Cast immobilisation may cause deep vein thrombosis and pulmonary embolism.

Are there are references that I need to consider?

Return to sports after ankle fractures: a systematic review.

Br Med Bull. 2013; 106:179-91

Del Buono A; Smith R; Coco M; Woolley L; Denaro V; Maffulli N

Abstract:

INTRODUCTION: This review aims to provide information on the time athletes will take to resume sports activity following ankle fractures.

SOURCES OF DATA: We systematically searched Medline (PubMED), EMBASE, CINHAL, Cochrane, Sports Discus and Google scholar databases using the combined keywords 'ankle fractures', 'ankle injuries', 'athletes', 'sports', 'return to sport', 'recovery', 'operative fixation', 'pinning', 'return to activity' to identify articles published in English, Spanish, French, Portuguese and Italian.

AREAS OF AGREEMENT: Seven retrospective studies fulfilled our inclusion criteria. Of the 793 patients, 469 (59%) were males and 324 (41%) were females, and of the 356 ankle fractures we obtained information on, 338 were acute and 18 stress fractures. The general principles were to undertake open reduction and internal fixation of acute fractures, and manage stress fractures conservatively unless a thin fracture line was visible on radiographs.

AREAS OF CONTROVERSY: The best timing to return to sports after an acute ankle fracture is still undefined, given the heterogeneity of the outcome measures and results. The time to return to sports after an acute stress injury ranged from 3 to 51 weeks.

GROWING POINTS: When facing athletes with ankle fractures, associated injuries have to be assessed and addressed to improve current treatment lines and satisfy future expectancies.

AREAS TIMELY FOR DEVELOPING RESEARCH: The best timing to return to sports after an ankle fracture has not been established yet. The ideas of the return to activity parameter and surgeon databases including sports-related information could induce research to progress.

 Determinants of outcome in operatively and non-operatively treated Weber-B ankle fractures.

Arch Orthop Trauma Surg. 2012; 132(2):257-63

Van Schie-Van der Weert EM; Van Lieshout EM; De Vries MR; Van der Elst M; Schepers T

Abstract:

INTRODUCTION: Treatment of ankle fractures is often based on fracture type and surgeon's individual judgment. Literature concerning the treatment options and outcome are dated and frequently contradicting. The aim of this study was to determine the clinical and functional outcome after AO-Weber B-type ankle fractures in operatively and conservatively treated patients and to determine which factors influenced outcome.

PATIENTS AND METHODS: A retrospective cohort study in patients with a AO-Weber B-type ankle fracture. Patient, fracture and treatment characteristics were recorded. Clinical and functional outcome was measured using the Olerud-Molander Ankle Score (OMAS), the American Orthopaedic Foot and Ankle Society ankle-hindfoot score (AOFAS) and a Visual Analog Score (VAS) for overall satisfaction (range 0-10).

RESULTS: Eighty-two patients were treated conservatively and 103 underwent operative treatment. The majority was female. Most conservatively treated fractures were AO-Weber B1.1 type fractures. Fractures with fibular displacement (mainly AO type B1.2 and Lauge-Hansen type SER-4) were predominantly treated operatively. The outcome scores in the non-operative group were OMAS 93, AOFAS 98, and VAS 8. Outcome in this group was independently negatively affected by age, affected side, BMI, fibular displacement, and duration of plaster immobilization. In the surgically treated group, the OMAS, AOFAS, and VAS scores were 90, 97, and 8, respectively, with outcome negatively influenced by duration of plaster immobilization.

CONCLUSION: Treatment selection based upon stability and surgeon's judgment led to overall good clinical outcome in both treatment groups. Reducing the cast immobilization period may further improve outcome.

 Risk factors for ankle fracture.

Osteoporos Int. 2001; 12(2):97-103

Greenfield DM; Eastell R

Abstract:

Ankle fractures are frequently observed in postmenopausal women although the pattern of incidence and risk factor profile suggest that ankle fracture may not be a typical osteoporotic fracture. The aims of this study were to determine the prevalence of osteopenia and vertebral fracture and to evaluate the diagnostic accuracy of dual-energy X-ray absorptiometry (DXA), anthropometry, lifestyle and reproductive factors in women who have sustained an ankle fracture. We studied 103 women aged 50-80 years (mean 63.2, 7.9 SD) with ankle fracture. These were compared with 375 women aged 50-86 years (mean 64.5, 9.1 SD) from a population-based cohort. Bone mineral density (BMD) at the lumbar spine (LS) and contralateral proximal femur (including femoral neck (FN), Ward's triangle (WT) and trochanteric region (TR)) was measured by DXA. Quantitative ultrasound (QUS) of the calcaneus and proximal digits was measured using three different devices. Radiographs of the thoracolumbar spine were taken (anteroposterior and lateral views). There were no significant differences in the prevalence of osteoporosis (T-2.5 level) at the LS, FN and WT sites. The population-based cohort had lower TR BMD than the ankle fracture cohort. Age-and weight-adjusted Z-scores of FN BMD were significantly lower in the ankle fracture group. Age- and weight-adjusted Z-scores of QUS gave contradictory results. There were no differences in the receiver operating characteristics of DXA compared with QUS. Twenty-seven women (7%) of the population-based cohort and 10 women (10%) of the ankle fracture cohort were found to have prevalent vertebral fractures; these were not significantly different.

 Long-term outcome of pronation-external rotation ankle fractures treated with syndesmotic screws only.

J Bone Joint Surg Am. 2013 Sep 4;95(17):e1221-7

Lambers KT, van den Bekerom MP, Doornberg JN, Stufkens SA, van Dijk CN, Kloen P.

Abstract:

BACKGROUND: There is sparse information in the literature on the outcome of Maisonneuve-type pronation-external rotation ankle fractures treated with syndesmotic screws. The primary aim of this study was to determine the long-term results of such treatment of these fractures as indicated by standardized patient-based and physician-based outcome measures. The secondary aim was to identify predictors of the outcome with use of bivariate and multivariate statistical analysis.

METHODS: Fifty patients with pronation-external rotation (predominantly Maisonneuve) fractures were treated with open reduction and internal fixation of the syndesmosis utilizing only one or two screws. The results were evaluated at a mean of twenty-one years after the fracture utilizing three standardized outcomes instruments: (1) the Foot and Ankle Ability Measure (FAAM), (2) the American Orthopaedic Foot & Ankle Society (AOFAS) ankle-hindfoot scale, and (3) the Center for Epidemiologic Studies-Depression (CES-D) Scale. Osteoarthritis was graded according to the van Dijk and revised Takakura radiographic scoring systems. Bivariate and multivariate analyses were performed to identify predictors of long-term outcome.

RESULTS: Forty-four (92%) of forty-eighty patients had good or excellent AOFAS scores, and forty-four (90%) of forty-nine had good or excellent FAAM scores. Arthrodesis for severe osteoarthritis was performed in two patients. Radiographic evidence of osteoarthritis was observed in twenty-four (49%) of forty-nine patients. Multivariate analysis identified pain as the most important independent predictor of long-term ankle function as indicated by the AOFAS and FAAM scores, explaining 91% and 53% of the variation in scores, respectively. Analysis of pain as the dependent variable in bivariate analyses revealed that depression, ankle range of motion, and a subsequent surgery were significantly correlated with higher pain scores. No firm conclusions could be drawn after multivariate analysis of predictors of pain.

CONCLUSIONS: Long-term functional outcomes at a mean of twenty-one years after pronation-external rotation ankle fractures treated with one or two syndesmotic screws were good to excellent in the great majority of patients despite substantial radiographic evidence of osteoarthritis in one-half of the patients. The most important predictor of long-term functional outcome was patient-reported pain rather than physician-reported function or posttraumatic osteoarthritis. There was no significant association between radiographic signs of posttraumatic osteoarthritis and perceived pain in the present series.

LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

 Ankle syndesmotic injury.

J Am Acad Orthop Surg. 2007 Jun;15(6):330-9.

Zalavras C, Thordarson D.

Abstract:

Ankle syndesmotic injury does not necessarily lead to ankle instability; however, the coexistence of deltoid ligament injury critically destabilizes the ankle joint. Syndesmotic injury may occur in isolation or may be associated with ankle fracture. In the absence of fracture, physical examination findings suggestive of injury include ankle tenderness over the anterior aspect of the syndesmosis and a positive squeeze or external rotation test. Radiographic findings usually include increased tibiofibular clear space decreased tibiofibular overlap, and increased medial clear space. However, syndesmotic injury may not be apparent radiographically; thus, routine stress testing is necessary for detecting syndesmotic instability. The goals of management are to restore and maintain the normal tibiofibular relationship to allow for healing of the ligamentous structures of the syndesmosis. Fixation of the syndesmosis is indicated when evidence of a diastasis is present. This may be detected preoperatively, in the absence of fracture, or intraoperatively, after rigid fixation of the medial malleolus and fibula fractures. Failure to diagnose and stabilize syndesmotic disruption adversely affects outcome.