Pilon fractures

NB This page is from the 2005 Hyperbook.
Last evidence check January 2005.

A pilon fracture is a fracture of the distal tibia involving the tibial plafond. Obviously there is some potential overlap with the more severe malleolar fractures; pilon fractures are usually understood to be those with involvement of the central plafond, although this has not been formally defined.

Pilon fractures account for about 5% of tibial fractures. It is difficult to estimate incidence accurately because almost all reported series are from major trauma centres and hence represent a very selected population.

Biomechanics

Ruedi and Allgower reported a seminal series of pilon fractures in 1980, most of which were low-energy twisting factures. However, almost every other series has found that a large majority of pilon fractures are caused by high-energy axial impaction injuries, with motor vehicle accidents and falls from 3 metres or more the commonest mechanisms of injury.

Pre-tensioning of the Achilles tendon and the position of the ankle and foot at the moment of impact may have an effect on the severity and anatomy of the fracture.

Classification

Two main classifications are used. Ruedi and Allgower described three groups:

I - no comminution or displacement of joint fragments
II - some displacement but no comminution or impaction
III - comminution and/or impaction of the joint surface

The AO long bone group universal classification of fractures groups distal tibia fractures as 43 and divides this into:

43A: extra-articular – most would not recognise these as pilon fractures, although they appear in some series
43B: partial articular fractures with some connection between part of the joint surface and the diaphysis
43C: complete articular fractures with no connection between the joint surface and diaphysis – most pilon fractures fall into this group which is subdivided into:
- 43C1: no comminution of epiphysis or metaphysis
- 43C2: comminution of metaphysis but not epiphysis
- 43C3: comminution of both metaphysis and epiphysis (corresponding roughly to Ruedi-Allgower group III, many pilon fractures are in this category)


AO C3 pilon (aren't they all!) - moderate displacement

More severe, open, C3 pilon with severe articular impaction and comminution

Clinical features

Most patients have a history of a high-energy axial injury and may have other associated injuries of the calcaneum, knee, hip or spine. Some series report polytrauma in 10-20% and 10-30% open fractures, but these were from level-1 trauma centres. Compartment syndrome of the foot has occasionally been reported after pilon fractures.

Assessment

Full ATLS primary and secondary survey is required for major injuries. Examine for neurovascular injuries, compartment syndrome and associated skeletal injuries. Assess the patient’s overall medical fitness, especially a history of vascular disease, diabetes or inflammatory arthritis and any major medical illness.

Plain AP and lateral radiographs should be obtained, along with imaging of any other associated injuries. Other initial investigations are obtained as clinically indicated.

CT is very useful in assessing pilon fractures. Tournetta (1996) found that CT influenced management in 60% of patients. Except in the emergency situation, we would not operate on a pilon fracture without a CT. Other imaging modalities probably add little to plain films and a CT, although this has not been formally evaluated.


CT of the first fracture above. The arrow indicates the primary fracture line. An incision here will lead to minimal soft tissue stripping (Tornetta 1996)

Management

Initial management includes resuscitation, pain control and splintage. Partial reduction may be indicated to prevent skin breakdown. Open injuries should be documented, cleaned and dressed.

Non-surgical management in a cast with avoidance of weightbearing in view of the disrupted plafond may be useful in a few undisplaced fractures (Ayeni 1988). Ayeni used plaster for 12 weeks and NWB for 10 weeks; there are no data to show whether such protracted restriction is necessary. Ayeni found that displaced or comminuted fractures did poorly in casts.

Surgery can be divided into two main groups:

Open reduction and internal fixation: popularised by Ruedi and Allgower, who emphasised plating the fibula to regain length, reduction of the plafond and bone grafting to support the articular surface followed by medial buttress plating. A long anteromedial incision was used, with undermining to reach the fragments. Unfortunately this has been associated with a high incidence of wound failure. More recently, reduction of the articular surface through a small incision related to the main fracture line without undermining, followed by minimally invasive insertion of a low-profile plate to attach the articular fragment to the shaft has been proposed and reported to have alower incidence of wound problems.
External fixation to regain length, often with minimally invasive reduction and stabilisation of the articular fragments. Bridging unilateral fixators, hybrid frames and full circular frames have been used.

Only one RCT has compared internal and external fixation. Wyrsch et al (1996) reported no difference in clinical outcome, but a higher incidence of severe soft tissue complications in the ORIF group. Allocation to treatment was not truly randomised and there were, in fact, more severe injuries in the external fixation group. The power of the study was low. Fixation was usually performed within the first week when the soft tissues might be expected to be swollen. It is difficult to draw useful conclusions from this study.

Several other retrospective comparative series have been reported (eg Williams 1998, Blauth 2001, Pollak 2003) with variable results.

Series reporting the results of external fixation include Watson (2000) – Ilizarov frame for severe soft tissue injuries only, Angelen (2001), Blauth (2001) – historical comparison group for minimally invasive plating, Tornetta (2003), Okcu and Aktuglu (2004), Williams (2004) and Pollak (2004). The results vary widely, partly because some series selected more severe fractures for external fixation. Most series carried out limited open reduction and screw fixation of the joint surface in addition to external fixation, and a variety of frame configurations were used. Okcu and Aktuglu compared transarticular and non-bridging Ilizarov frames retrospectively; the Ilizarov group got a better range of movement but the Olerud ankle scores were similar. Williams compared external fixation with and without fibular plating; fibular plating prevented malunion but at the cost of many lateral wound complications, and the malunions were asymptomatic – Williams recommended a selective approach to fibular plating. In most series the rate of wound infection with fixators was lower than in ORIF and pin track infection rates were manageable. Malunion rates vary from 4-20% and some series report a number of metaphyseal-diaphyseal non-unions.

Series reporting the results of ORIF include Ruedi and Allgower (1988), Teeny and Wiss (1993), Watson (2000) – for mild soft tissue injuries only, Paterson and Cole (1999), Blauth (2001) and Syed and Panchbani (2004). Teeny and Wiss were among the first to draw attention to the high rate of wound problems in high energy injuries fixed by the methods of Ruedi and Allgower – half their grade III injuries had poor clinical results due to a combination of inadequate reduction, malunion (23%), non-union (27%) and infection. Restricting ORIF to those with mild soft tissue injuries (Tscherne grades 0-1), Watson reported 14% wound failure, 5% deep infection, 11% non-union and 4% malunion. Both Paterson and Cole and Blauth advocated temporary external fixation or traction with delayed ORIF at about 14 days (Blauth also used minimally-invasive plating rather than the traditional technique). Paterson and Cole’s series consisted of 22 AO 43C3 fractures only but they had no wound problems or deep infections, one malunion and one non-union. Blauth had a 12% infection rate but no malunion or non-union. Syed and Panchbani described a percutaneous screw technique which is applicable in Ruedi/Allgower I and II fractures and avoids wound problems without significant bone healing problems in a small series.

At the moment bridging, hybrid or circular external fixation, or delayed ORIF, possibly with minimally invasive plating, can all be justified for the management of pilon fractures. Techniques for both internal and external fixation have improved since Wyrsch’s RCT, and further large trials with better methodology, perhaps across several centres to get adequate numbers, would be justified. However, these are quite heterogenous fractures, and it may be difficult to apply the results of even quite a large trial. It may be that several options will continue to have a place, with each surgeon being responsible to monitor their own complications.

Stabilisation of pilon fractures

Traditional AO plate fixation	AO LCP pilon plate - the plate sits off but is not a problem	AO hybrid frame

Outcomes

A number of recent series (Marsh 2003, Pollak 2003, Williams 2004) have concentrated on the overall clinical outcomes of pilon fractures, using general outcome measures such as the SF-36 as well as ankle scores. All agree that after 2-5 years, patients who sustain a pilon fracture still have significantly poorer general health scores than the average population. 15-30% were disabled and 40% had changed jobs as a result of the fracture. OA was present in 50% or more patients, usually within 2 years, but clinical outcome correlated poorly with OA severity. The overall rate of fusion for post-traumatic OA was about 10%. Marsh found that patients continued to improve for up to 5 years after a pilon fracture and this should be borne in mind when assessing results from shorter follow-up. The main predictors of final outcome were the severity of the original injury (in all series) and the quality of the initial reduction.