Internal fixation of “Nutcracker” Fracture of the cuboid- Stryker VariAx 2 Foot System

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The cuboid bone is the keystone of the lateral longitudinal arch of the foot. Together with the calcaneus and the lateral two rays of the foot (the 4th and 5th metatarsals and corresponding phalanges) it makes up the central bone in the lateral column of the foot. The medial column then is composed of the talus, navicular, cuneiforms and the medial three rays of the foot. Owing to its intimate relationships with its surrounding architecture, the cuboid is rarely injured in isolation, especially in higher energy injuries where navicular fractures are often also associated and my colleague in Sheffield, Mr Mark Davies has described these in the Navicular Fracture Orthoracle Operation.
The, calcaneo-cuboid joint together with the talonavicular joint, forms the transverse tarsal joint, crucial for effective gait – absorbing energy in heel strike and stiffening to aid in propulsion. The combination of these two joints is commonly referred to the Chopart joint.
The term Nutcracker Fracture was coined by Hermel and Gershon-Cohen in the Radiology journal in 1953. It was because of the compressive forces that exist towards the cuboid in forced abduction that they felt the bone burst as if it were in a Nutcracker
Acute, traumatic fractures of the cuboid bone are relatively uncommon with an incidence of 1.8/100,000/year and are frequently associated with other midfoot fractures (Classification and epidemiology of mid-foot fractures AUCourt-Brown CM, Zinna S, Ekrol I; The Foot. 2006;16:138). The severity of the cuboid fracture lie on a spectrum dependent upon the amount and nature of the energy imparted across the bone. Injuries range from simple ligamentous avulsions associated with ankle sprains through to crush injuries not only involving the cuboid but also the navicular and have been comprehensively classified into five groups in a recent paper from the Sheffield Foot and Ankle Unit. These latter, high-energy injuries have been shown to correlate with significant long-term morbidity and adverse function especially in the multiply injured patient. Failure to restore the anatomic relationships of the bony components within both columns, together with their relative column length, can result in significant morbidity. Like navicular fractures, those of the cuboid bone can be subtle and diagnosis is frequently delayed, either through inadequate imaging or the presence of other significant, distracting injuries in the multiply injured patient.
This case is a 27 year old male who was the driver of his car involved in a front end collision. He sustained an isolated injury to his right foot which was initially missed in the Emergency Department who felt that his foot radiographs were normal. The injury was thankfully recognised in the fracture clinic where the abnormal contour of the articulation between the cuboid and the 4th and 5th metatarsals was spotted. From that fracture clinic he subsequently underwent a CT scan defining the injury as seen above. In light of the displacement at the joint surgery was recommended and he underwent the procedure described here one week post injury.

INDICATIONS
I use the following features of the fracture on CT scan to determine whether operative reduction is needed:
1. significant adjacent joint disruption,
2. lateral wall blow out interfering with peroneal tendon excursion,
3. lateral column shortening which will result in late abduction or pes planus deformity
4. instability (particularly in type 5 fractures with navicular involvement)

SYMPTOMS & EXAMINATION
Swelling and an indicative history are the cardinal features. Usually the violence has been high energy, a fall from height or a road accident but beware of the innocuous low energy fall which can result in a fracture which can be easily missed too though will still result in pain and swelling. The swelling and the site of pain are usually well localised to the cuboid bone and fracture site.
IMAGING
Plain radiographs should be a series that includes lateral, antero-posterior and an oblique view. If the injury is seen or even suspected then in my practice a CT scan is ordered. This is vital to clarify the pattern of injury, define associated injuries and allow classification. From this, the degree of adjacent articular damage can be elucidated and the stability of the lateral column can be deduced. If there is significant disruption to the joint surfaces or the cuboid is fractured such that the lateral column is short then surgery should be considered.
ALTERNATIVE OPERATIVE TREATMENT
If the lateral column is very short and the fracture includes a distal calcaneal fracture or subluxation of the 4th and or 5th tarso-metatarsal joints then a bridging external fixator is a useful alternative and may be left as definitive treatment for 6 weeks as the image above which was for a different case with dislocations of the 4th and 5th metatarsals in addition to the cuboid fracture.
If the joint surface cannot be restored at the time of surgery, the the joint involved, be that the Calcaneocuboid or the 4/5th tarso-metatarsal joints, could be bridged with a locking plate internally. This will need to be removed later however to allow motion of the lateral column to be regained – I remove these plates at 3 months though I have only rarely used them.
In complex and displaced fractures fusion might be tempting. In my opinion this should be avoided if at all possible. The cuboid bone articulates proximally and distally to allow the flexibility of the lateral column of the foot. it is this lateral column motion which allows the foot to accommodate for uneven terrain. Fusions result in significant alterations of gait and the residual stiffness is poorly tolerated by all but the most sedentary.
NON-OPERATIVE MANAGEMENT
If the joints either side are not involved, the lateral wall is not significantly blown out and the lateral column is both out to length and stable then non-operative management is indicated. This involves a period (usually 6 weeks) of immobilisation in a boot with physiotherapy for range of motion at the transverse tarsal joint and I prefer to keep the patient non-weight bearing for 6 weeks to avoid late deformity with fracture displacement. Non-operative management is associated with a poor outcome for displaced fractures however (see references below)
CONTRAINDICATIONS
Significant co-morbidities or vascular compromise are contraindications to operative involvement. Non compliance is for me a relative contra-indication as I am concerned about wound healing problems in those that do not adhere to our advice.
TIMING OF SURGERY
Early intervention makes reduction easiest but respect for soft tissues remains paramount. To this end a very swollen foot should wait. Sometimes the swelling can take 2 or 3 weeks to resolve. If there is significant instability (type 5 fractures particularly) I would advocate bridging fixators to gain stability and keep the foot “safe” whilst swelling settles. The pins should be positioned in such a way as to avoid the wound.

The patient has either a spinal or general anaesthetic for this procedure. Patient is positioned supine with a sandbag or support as there is often the need to turn attention medially for a navicular or medial column fracture and I prefer simply to remove the sandbag to facilitate this. If you are certain that no medial approach will be needed then the patient could be positioned laterally.
I use a thigh tourniquet and prep the limb to and including the knee for alignment purposes.
I use an image intensifier (occasionally a mini C-arm can be used – and has the advantage of being actuated by the surgeon) and I get the arm to come in from the opposite side to the fracture.

The back slab is kept on for two weeks. During this time the patient is asked to keep the limb elevated to horizontal most of the time. They take thromboprophylaxis according to Hospital guidelines (our Trust uses Rivaroxaban a Factor Xa inhibitor) for 2 weeks. After this time I remove the cast and inspect the wound. If all is well and the patient reliable they go into a non-weight bearing removable boot with range of movement advice to be used for a further 4 weeks. If compliance is an issue then a NWB cast is continued for a further 4 weeks.
At 6 weeks post operative a radiograph is taken and if satisfactory then weight bearing can commence with the guidance of a physiotherapist.
As weight bearing becomes easier the boot and crutches are finished with and the patient discharged at 12 weeks review.

Fenton P, Al-Nammari S, Blundell CM and Davies MB. The patterns of injury and management of cuboid fractures: a retrospective case series. BJJ 2016 July;98-B: 1003-8
The largest series of cuboid fractures involving 192 fractures from Sheffield, UK. We classified them and used this classification to guide treatment and provide rationale and strategy for doing so. This publication was followed by our sister classification of navicular fractures which is referenced in the Orthoracle Navicular Fracture case published by my colleague Mark Davies.
Holbein O., Bauer G., Kinzl K. Displaced fractures of the cuboid: four case reports and review of the literature. Foot and Ankle Surgery. 1997;3(2):85–93
There are no long term large series on the outcomes of displaced cuboid fractures and the treatment methods reported vary. Modern articles which are usually case series of no more than 4 cases (as in this article) report on the use of plates to restore the cuboid whilst at the same time preserving motion at the proximal and distal joints. Only Holbein O et al have been prepared to put figures together suggesting that fractures displaced by more than 1mm or where the lateral column is shortened by 3mm or more require operative reduction. They report results in their 4 cases as being good in two and excellent in the other two.
Hermel MB, Gershon-Cohen J. The nutcracker fracture of the cuboid by indirect violence. Radiology. 1953;60:850–4
The original article published in the premier radiology journal in which the Nutcracker term was coined. Theses fractures were described in association with Chopart joint fractures. Read for historic interest only as they recommended fusions as the treatment required as they felt that the lateral border of the foot was ‘primarily rigid and static’. It was easy to publish then!
Sangeorzan BJ and Swiontkowski MF. Displaced fractures of the cuboid. J Bone Joint Surg Br. 1990;72:376–8
The Seattle surgeons with a particular interest in Chopart injuries published a series of 4 cases in which rather than fusions they maintained the length and restored the joints in displaced fractures. They are the forefathers of the Sheffield groups thinking of the column lengths and the value of joint preservation
Main BJ, Jowett RL. Injuries of the midtarsal joint. J Bone Joint Surg Br. 1975;57:89–97
This earlier publication was on 4 cases also of displaced fractures of the cuboid. Treatment of the fractures was non-operative and results were fair to poor in all four which all went on to have triple fusions later.