The Tibia

Fractures of the tibial shaft can occur after repetitive loading (stress fractures) or following a single major traumatic event. The tibia is a subcutaneous bone on its anteromedial margin and so any significant displacement of the fracture is likely to result in an open injury. This skin over the tibia is also a notoriously poor healer, and therefore the open fracture of the tibia is an especially challenging problem for the trauma surgeon.

Mechanism of injury

The mechanism of injury is particularly important with respect to the energy involved, likely contamination of the wound and subsequent problems with healing.

Stress fractures

Stress fractures are particularly common in the tibia, particularly in runners. The patient initially complains of pain during exercise, then pain during and after exercise, and finally pain at all times. On examination there may he little to find except for the fact that the tibia may be tender to percussion. Initially the X-ray may be normal but after some weeks a faint haze of callous may form locally over the site of the invisible fracture. This X-ray, if combined with a history of continuous pain, is also characteristic for osteosarcoma. Careful imaging with MRI or CT scan should be able to distinguish these two diagnoses.

Management of stress fractures. This condition can prove very difficult to manage. It may occur at a crucial phase in an athlete’s training programme and at some stage, preferably sooner rather than later, it is going to become clear that training for the next few months, or indeed that season, is over. This can be very difficult for an athlete to accept, but until it is the condition is unlikely to settle. One problem may be the boredom that sets in if the significant proportion of the day, which was previously devoted to sport, is now to be spent resting. The alternative is to devise forms of exercise which are as strenuous and as time-consuming as the original activity, but which do not stress the tibia. For runners the nearest sport is cycling, a more remote possibility swimming. As the fracture is incomplete, it should not require any extra protection.

Low-energy direct blow fractures to the tibia

The tibia may be broken by a direct blow such as a bumper injury to a pedestrian. Despite the low-energy nature of the injury the skin and soft tissues may be damaged over the fracture, so the fracture may be technically open. If the fracture is a simple transverse fracture or a small butterfly fragment the fracture may be stable to axial compression. In this case nonoperative treatment will be best. If, however, there is a large butterfly fragment the fracture is likely to be unstable and treatment in plaster may lead to unacceptable shortening. Because of its subcutaneous position the tibia is ideally suited to the use of an external fixator (Fig. 23.36), except that the tibia is slow-healing bone and external fixators on the whole delay healing rather than stimulate it. Nevertheless, an external fixator offers a viable option where facilities for internal fixation are limited, or where it is felt that the damage to the skin and soft tissues over the bone makes the risk of internal fixation too high.

Internal fixation can be performed using either a plate or an intramedullary nail. A plate cannot be fixed on the anteromedial border of the tibia because it is subcutaneous. If there is any soft tissue defect then a careful plan will need to be made with the plastic surgeons to ensure that cover of the fracture and plate can be obtained. This may mean rotating a musculocutaneous flap. A plate cannot be applied if cover cannot be obtained. Some surgeons apply bone graft to all tibial shaft fractures which are plated because of their reputation for poor healing.

The tibia is well suited to intramedullary nailing (Fig. 23.37), especially using the newer type of unreamed nail. Fixation can be obtained without unduly disturbing the frac­ture. Proximal and distal locking provides control of axial compression and gives rotational stability. A nail allows immediate mob ilisation of the patient, although with the un-reamed nail they should probably remain partial weight-bear­ing on crutches for the first 6—8 weeks. The technique can apparently be used without undue risk of infection even in open fractures provided that there is no significant contamination or major soft-tissue damage. The operation should only be performed by an experienced team with excellent X-ray image intensifier facilities as the complication rate of this operation is high even in experienced hands.

Operative technique for unreamed intramedullary nailing

The patient is placed supine on a fracture operating table and the tibia set either vertically with the femur horizontal or horizontally with the femur vertical with the tibia above the rest of the table. Either way, the opposite leg must be put in a different position so that the image intensifier can get a clear AP and lateral view of the whole length of the tibia. The knee must be bent up to the right angle to obtain access to the front of the tibia. A Steinmann pin may be inserted into the calcaneum to provide the traction needed to hold the tibia straight. If the tibia is allowed to hang vertical then the weight of the tibia will provide that traction, but access from the image intensifier may be more difficult. A small incision is made over the medial margin of the patella tendon and the entry area on the extra-articular superior surface of the tibia is identified by pushing back the fat pad with a periosteal elevator. An entry hole is made into the tibia in the midline 2 cm back from the anterior margin. A guide pin is inserted and a check made on the image intensifier that the pin is indeed central and can be induced to pass down the tibia, not out of the posterior cortex. This is only possible if the knee is flexed at least 90 degree so that the roll back of the knee joint moves the femoral condyles and patella back out of the way. It also relies on the entry point being made well enough forward to allow the pin to pass vertically down the tibia without impinging initially on the anterior cortex and further down on the posterior cortex.

Leaving the guide pin in place a circular cutter should be introduced over this pin to open up a entry hole in the top of the tibia. A guidewire should then be introduced and passed beyond the fracture down to the sclerotic remains of the growth plate immediately above the ankle joint. Its length should be measured and an unreamed nail mounted on its introducer, checking that the proximal screw guides are on the medial side and that the nail’s curve is concave anteriorly. The nail should be gently driven down, taking great care that initially it does not penetrate the posterior cortex. When it reaches the fracture site the nail should be driven slowly across the fracture site under direct image intensifier control until the tip is lust above the ankle joint. The image intensifier should then be centred over the distal holes making sure that the image of each hole is round and not oval, and is exactly in the centre of the image intensifier screen. Through a small skin incision the drill should then be passed through the bone and through the locking hole. The length of screw needed is measured with a depth gauge, and the two distal screws are introduced from the medial side. The traction should then be removed and the nail at the proximal end hammered back a little to draw the two fragments together, as they may be slightly distracted when the nail is driven down. The jig is used to put locking screws in the proximal end after once again checking that rotation is correct.

A final check is made using the image intensifier to ensure that all screws are passing through the nail and engaged on both cortices (Fig. 23.38). A check is also made of the distal circulation. Postoperatively, sensation should be checked and the patient put under observation to ensure that circulation to the foot is maintained and that a compartment syndrome is not developing. The operation and immediate postoperative period should be covered with prophylactic antibiotics. The patient can start mobilising the next day but should remain on crutches until the fracture starts to unite. If the patient cannot he trusted to be careful then it may be wise to put on a plaster gaiter to protect the nail.

Management of the severely crushed tibia

In the high-energy injury to the tibia or where there are has been severe crushing, the fracture may be highly unstable, contaminated and surrounded by damaged soft tissues which cannot cover the fractures (Fig. 23.39). The patient will need resuscitating and a check made for other injuries. The neuro­vascular status of the foot distal to the fracture will also need to be checked. Where possible, Polaroid photographs should be taken and then the fracture site wrapped in sterile saline swabs. The management of this fracture is going to be by a team approach but the continuous re-exposure of the fracture for each member of the team to inspect should be avoided as this will increase the overall risk of infection. The first decision which will need to be made is whether the limb is salvageable at all or whether an early amputation will provide the quickest return of the patient to active life. In the case of land mine injuries, the damage appears to be more severe the further distal one goes and the decision on amputation can be a simple one. In isolated injuries of the tibia, however, the decision will depend on the age of the patient and the function of the distal limb. If the patient is elderly or the distal limb’s sensational vascular supply is compromised then serious consideration must be given to whether the unit has the expertise to provide this patient with a sensate and functional foot and union of the tibia. The worst possible scenario is to find that the limb is not salvageable after a year of heroic effort. By then the patient’s morale will be sapped and amputation is unlikely to lead to a rapid return to independent living. In contrast, an early amputation followed by rapid rehabilitation through a limb-fitting unit might have allowed return to work within 6—8 weeks.

Complications of tibial fracture and their management

Loss of circulation to the foot

This is the most important complication and treatment must be started immediately. If the limb is angulated it should be put straight immediately in case the cause is merely kinking vessels to the foot. If this does not produce an immediate improvement in circulation and the patient is young enough for a repair of the vessels distal to the trifurcation to be a possiblity, then arrangements need to be made immediately for surgery with an arteriogram on the table. In some units a temporary stent is inserted to start reperfusion of the foot before stabilisation of the fracture is attempted. In other units the fracture is first stabilised. Otherwise there is a risk of disrupting the vascular repair when stabilising the fracture. However, stabilising the fracture significantly prolongs the warm ischaemic time of the foot so if it is decided to stabilise the fracture first then this must be done as quickly as possible. When circulation returns to the lower limb there is a high probability of developing a compartment syndrome. Fasciotomies will usually be required.

Neurological damage to the lower limb

If the soft-tissue damage around the fracture is so extensive that the nerves cannot be repaired then primary amputation should be considered. An insensate limb is unlikely to be of any use to the patient. If the nerves are damaged in con­tinuity, then some recovery can be expected and salvage of the limb should be attempted. In closed injuries it is likely that damaged nerve is in continuity and reasonable recovery can be expected provided that the blood supply to the foot is restored as quickly as possible.

Infection

Infection of closed tibial fractures should be rare but of open tibial fractures is common. All fractures with a puncture wound over them, however small, should be treated as open fractures with contamination. They are all treated in the same way. The skin edges of the wound should be excised and the wound extended so that a clear view of all damaged tissue can be obtained. Any dead and necrotic tissue should be removed and the wound should be washed out with several litres of saline. The wound should be left open and re-inspected at 24 hours. Again, any necrotic or contaminated tissues should be excised and the wound washed out. This process should be repeated until the wound is clean. When this occur delayed primary close can be performed. Throughout this time high levels of intravenous broad-spectrum antibiotics should be used aimed at covering Staphylococcus, Streptococcus and Clostridium. If infection develops when internal fixation is in place then the surgeon is caught on the horns of a dilemma. Stabilisation of the fracture is needed to bring infection under control but foreign material may be acting as a focus for the infection. If a nail is in place then exchange nailing may need to be performed under intravenous antibiotic cover. If a plate has been used then this too may need to be replaced and all infected tissue excised and the wound washed out. An alternative is to change fixation to an external fixator while removing all internal metal ware.

Compartment syndrome

A compartment syndrome may develop at any time in the first 48 hours after the accident or after surgery. The patient usually complains of severe unremitting pain with some numbness in the foot. The foot may be cold but there may still be pulses even though a compartment syndrome is developing. Passive Dorsiflexion of the toes produces severe pain in the leg. There are no reliable investigations for compartment syndrome and if the condition is suspected then the suspicion should be acted on.

Operation note for fasciotomies

The Mubarek fasciotomy is probably the most reliable form as it ensures that all four compartments are decompressed. An anterolateral incision allows the anterior and perineal compartment to be entered through one incision. Care is taken not to damage any nerves running in the fascia. The fascia is divided, first with a sharp knife and then with a pair of scissors, under direct vision. If a compartment syndrome is present the muscle will pout out a deep purple in colour, and if the fasciotomy was performed soon enough the muscle will then pink up. A second incision is then made posteromedially allowing decompression of the superficial and deep posterior compartments. The deep posterior compartment is the most likely site for a compartment syndrome. If any dead muscle is found it should be excised. Even if no dead muscle is found the wound should be left open and reinspected at 24—48 hours when it will be easier to see whether muscle is dead or viable. At that stage all dead muscle can be excised and closure performed with a split skin graft or with a fasciotomy closure device (Fig. 23.40).

Nonunion

Atrophic nonunion of the tibia is not uncommon. The blood supply to the mid shaft of the tibia is not good and the soft-tissue cover is also minimal. High-energy trauma may strip the periosteum off the tibia and infection may further com­promise healing ability. If after 8—12 weeks the tibia is showing no radiological signs of union then delayed union is occurring and may go on to nonunion. If a plate or nail has been used there is a risk that the metalwork will fatigue before the fracture unites. Bone grafting can be used to stimulate callus formation. If an intramedullary nail is already in place then exchange nailing may need to be considered to stabilise the fracture with a new nail which has not yet started to fatigue. Hypertrophic nonunion usually develops if there is too much movement at the fracture site. This is unlikely to occur if internal fixation or an external fixator is used but might occur if a plaster is used to hold the fracture.

Treatment. The fracture site should be opened and the cleft of the fracture cleaned of all fibrous tissue. Consideration should then be given to inserting a reamed nail or putting on a carefully moulded plate to compress the fracture ends and stabilise them. Bone graft should then be put around the fracture site. The patient should only be mobilised under careful supervision of a physiotherapist.