Introduction

Avulsion fractures of the calcaneal tuberosity are uncommon injuries. It constitutes 1-3% of all calcaneal fractures (1) whereas calcaneal fractures comprise only 1-2% of all fractures (2). Up to date, there are only limited literatures on the treatment of these fractures.

The most common cause of avulsion fractures of the calcaneal tuberosity is forced dorsiflexion of the foot (1). Other causes such as concentric contraction of gastrocnemius-soleus complex with the knee in full extension and direct trauma are also described (1). Factors that increase the risk of such fractures include diabetes, female, osteoporosis and neuropathic diseases (3). Patients with these fractures usually present to the hospital early due to painful swelling and difficulty in weightbearing. Minimally displaced fractures can be treated conservatively (4). Significantly displaced fracture usually requires early surgical treatment with open reduction and internal fixation to avoid skin necrosis as the fragment may impinge the fragile skin of the posterior heel (4). Even with treatments, there is a high complication rate up to 61.9%, with soft tissue complication rate up to 39.4% (5, 6). In this report, we describe a case of neglected avulsion fracture of the calcaneal tuberosity in a patient with pre-existing neurological deficit. In order to minimise complications in this high-risk patient, she was treated with osteoscopic assisted percutaneous reduction and screw fixation.

Case report

A 64-year-old woman with history of hypertension, subarachnoid haemorrhage with right hemiparesis and fracture right patella was admitted to our orthopaedic unit for right foot pain and swelling after a fall about 8 weeks ago. She reported no bruises, wounds or blisters over her right foot all along. Initially, she attended to a Chinese medical practitioner and she was treated with topical medication. However, with persisted pain despite treatment, she decided to attend the emergency department for further investigation. On examination, there was no obvious deformity, swelling or tenderness over her right foot. X-ray and CT scan of her right foot revealed a Beavis type II avulsion fracture of the calcaneal tuberosity with sclerotic and smooth fracture edges.

Surgery was performed under general anaesthesia. The patient was placed on prone position. A 1 cm stab incision was made over lateral side of fracture site under image intensification. Osteoscopy was performed through the stab wound using standard arthroscopy setup including a 30-degree arthroscope. Another 1cm stab incision was made over medial side of fracture site under osteoscopic guidance for insertion of osteoscopic instrument. Fracture callus was debrided by 4.0mm arthroscopic shaver until bleeding cancellous bone was observed. After debridement, 5mm stab incisions medial and lateral to Achilles tendon at the superior aspect of the posterior calcaneus were made. The ankle was plantarflexed and fracture fragment is reduced with pointed reduction forceps. Small bone void was noted after reduction. ChronOS Strip Bone Void Filler was inserted to the fracture site. Two bicortical 6.5mm cannulated screws were inserted over guide wires perpendicular to the fracture line in standard fashion. Short leg cast was applied with ankle in 10 degrees of plantarflexion. A window over posterior aspect of the cast was made for wound care. Postoperatively, she was put on non-weight-bearing walking for 8 weeks, partial weight-bearing walking for another 6 weeks and full-weight-bearing walking afterwards. Short leg cast was changed to ankle-foot-orthosis in plantigrade at week 4 postoperative and active mobilization exercise was allowed. The wounds healed well in 2 weeks postoperative. Radiographic union of the fracture was confirmed week 13 after the operation. In week 30 postoperative, the patient had good active range of motion of the ankle. She was satisfied with small and nicely healed scars. She could stand on tip toes, and she was able to walk with one stick for more than 1 hour. The Visual Analogue Scale for pain was 2/10 and the AOFAS (American Orthopaedic Foot & Ankle Society) hindfoot scale was 84 out of 100.

Figure 1

X-ray right foot showing a displaced avulsion fracture of the calcaneal tuberosity. Fracture callus can be seen.

Figure 2

CT scan of right foot showing displaced avulsion fracture of the calcaneus with sclerotic edge

Figure 3

Photo demonstrating osteoscope and arthroscopic shaver inserted into fracture site through two small stab wounds

Figure 4

Intraoperative osteoscopy showing callus at fracture site

Figure 5

Intraoperative osteoscopy showing bleeding from cancellous bone after debridement of callus with arthroscopic shaver

Figure 6

X-ray of the right ankle showing the lateral view on the first postoperative day

Figure 7

X-ray of the right ankle showing the axial view on the first postoperative day

Figure 8

Photo showing postoperative scar at posterior foot

Figure 8b

Photo showing postoperative scar at lateral foot

Figure 9

Photo showing active dorsiflexion of the foot

Figure 10

Photo showing active plantarflexion of the foot

Figure 11

Photo showing patient standing on tip-toe viewing from the back

Figure 12

Photo showing patient standing on tip-toe viewing from the side

Figure 13

Lateral X-ray of the right ankle showing healed calcaneus fracture with no loosening of screws at week 30 postoperative

Figure 14

Axial X-ray of the right calcaneum showing healed calcaneus fracture at week 30 postoperative

Discussion

Avulsion fracture of the calcaneal tuberosity was classified by Beavis et al into 3 types (7) . Type 1 is a “sleeve” fracture. Type II is a “beak” fracture in which there is an oblique fracture line running posteriorly from just behind Bohler’s angle. Type III is the infra-bursal avulsion fracture from the middle third of the posterior tuberosity (7). Soft tissue complications are not uncommon as the displaced fracture fragment may cause skin impingement at the posterior heel (8, 9). In many cases, this fracture can be treated with open reduction and internal fixation using minimally invasive posterior approach (4). However, for patients who presented late, callus formation over fracture ends may render percutaneous reduction difficult and may increase risks of malunion or non-union. Standard extended lateral approach can be used for better exposure, but it carries risks of damaging the sural nerve and vascular supply of soft tissues leading to skin edge necrosis and infection. The use of osteoscopy can preserve soft tissues and reduce risk of neurovascular injuries as only small stab incisions are needed. Moreover, it provides direct visualisation of the fracture site with magnified image projects onto large monitors. This allows more precise debridement of callus while preserving vascularised bone (10). Complete removal of fibrotic tissue and callus can be confirmed by presence of bleeding cancellous bone. Besides, this technique only requires standard arthroscopic equipment which is readily available in many centres, and it does not carry extra surgical risks. There are some drawbacks of this technique. It requires trained nurses and surgeon for operating osteoscopic instruments (10). Extra time is needed for set up of the equipment (10). Operation time may be longer comparing with open reduction and internal fixation (10).

In our case, osteoscopy was useful in removing callus and allowed good reduction of the displaced fracture. There was no postoperative wound complication or secondary loss of fixation. AOFAS score (84) of the patient was higher than the mean AOFAS score (74.36) in the study conducted by Carnero-Martín et al (5). She had low pain score with good functional outcomes despite her premorbid status.

In conclusion, this study demonstrates that osteoscopy assisted percutaneous reduction and fixation of avulsion fractures of calcaneal tuberosity results in good surgical and functional outcomes. This technique may also be used in other extra-articular calcaneus fractures or tongue type intra-articular calcaneus fractures, but its efficacy needs to be confirmed in larger number of patients.