Nonunion of the clavicle—introduction
Introduction
Most fractures of the clavicle involve the midshaft. Fortunately surgery is rarely indicated for these fractures because in the vast majority of cases nonoperative treatment will lead to an acceptable result—even if, in general, healing leads to some kind of malunion and shortening of the clavicle in comparison to the noninjured side.
A recent systematic review of 2,144 midshaft clavicle fractures showed that nonoperative treatment of 1,145 fractures resulted in a nonunion rate of 5.9%. When limited to 159 displaced fractures, the nonunion rate increased to 15.1% [1].
It is obvious that open fractures, initial displacement, and comminution predispose to the development of nonunions. The same is valid for fractures of the lateral clavicle. This might be one of the reasons for the tendency to stabilize dislocated fractures by minimally invasive techniques, such as flexible nails.
In the past, one of the etiological factors for the development of a nonunion was the insufficient initial operative treatment. We will have to wait and see if minimally invasive techniques will lead to better results.
Concerning the treatment of midshaft nonunions, plate fixation seems to be the method of choice [2, 3]. For lateral, or the extremely rare medial nonunions, tension band constructions are useful [4].
Classification
Beside the location (middle, outer, and lateral third), the type (atrophic, oligotrophic, and hypertrophic) of nonunion is important for the choice of treatment. The defect nonunions are a special problem.
Preoperative evaluation
Complaints by patients typically range from a mild aching during overhead activities to a severe and disabling persisting pain with impaired function of the shoulder girdle and upper limb; esthetic problems may be another reason to request treatment (Fig 2.1.1-1).
A concomitant symptom of nonunion often not recognized or mentioned in the literature is brachialgia which is present in about 30% of the patients [3]. Brachialgia is defined as a paresthesia or any numbness in the arm with or without associated muscle weakness. Usually this involves the medial aspect of the arm and is caused by compression of the brachial plexus by the medial fragment, which is pulled downwards (Fig 2.1.1-2), or by excessive callus formation.
Extensive diagnostic evaluation is not necessary. Local pain, crepitation, and pathological motion are easy to palpate.
A careful neurological examination is very important as the subclavicular area not only contains the brachial plexus, but also the subclavian vessels. Neurovascular symptoms may range from mild brachialgia to a full-blown thoracic outlet syndrome. Preoperative documentation of those mostly ulnar nerve symptoms is important because they can also appear after an inadequate stabilization of the nonunion, especially in hypertrophic midshaft nonunions where the medial cord crosses the clavicle.
Plain AP x-rays of both clavicles generally are sufficient for radiographic diagnosis. CT scans are not necessary and an MRI may exceptionally be used when there is evidence of severe neurovascular symptoms.
Preoperative planning
Midshaft clavicular nonunion
Plating, often in combination with iliac crest bone grafts, is the method of choice. Flexible nails do not provide the necessary absolute stability for the treatment of a clavicular nonunion.
The gold standard, based on biomechanical considerations, is the superior plate position. Treating a series of 28 midshaft nonunions the author used the straight dynamic compression plate (DCP) 3.5. Possible alternatives are the reconstruction plate 3.5 and the new generation contoured locking compression plate (LCP). Putting the plate on the superior surface of the clavicle means a noninvasive, easy access without extensive devascularization of the bone. It allows waving of the plate to create bridging bone formation under the plate by autogenous cancellous bone grafts and thus avoiding callus formation at the inferior part of the clavicle, which could lead to brachial plexus impingement syndromes. A possible disadvantage is the fact that the plate lies directly under the skin, often an indication to remove the implant after healing of the nonunion. This is one of the reasons why some authors prefer the anteroinferior position of the plate (LC-DCP), which might need a more invasive approach [5]. A good indication for the anteroinferior plate may be the hypertrophic midshaft nonunion after conservative fracture treatment in which the inferior callus has to be removed anyway. Superior plate position is clearly indicated in cases of earlier interventions; inferior plating would denude both surfaces of the clavicle as well as large defect nonunions in which the plate has to be fixed at the very end of the clavicle, which is almost impossible from below. The various plate positions are shown in Fig 2.1.1-3.
Independent of the final plate position, standard nonunion techniques are used: careful decortication, opening of the medullary canal on both sides with drill holes (no further shortening by resection), resection of the inferior excess callus in case of a hypertrophic nonunion to avoid postoperative neurovascular impingement.
Reduction of the nonunion and comparison with the opposite, healthy side will show if lengthening by an interposition bone graft is necessary. Shortening by compression of the nonunion of more than 1cm should be avoided; glenohumeral and/or scapulothoracic dysfunction or even a thoracic outlet syndrome could be the consequence.
Draping of the ipsilateral iliac crest is part of the preoperative planning. Only in real hypertrophic nonunions without shortening the excessive callus can be used as a bone graft under the wave plate or around the nonunion if an inferior plate is used.
In smaller defects, or if lengthening is necessary, a bicortical interposition bone graft taken from the inside of the iliac crest (see chapter 1.4.2 “Autogenous bone grafting in the treatment of nonunions”) is compressed by a straight DCP 3.5. The medial and lateral aspects of the graft are sculptured into pegs and plugged into the prepared medullary canals on either side. The cortical part of the autogenous cancellous bone graft is used to reconstruct the inferior border of the clavicle in order to create a smooth surface, avoiding any excessive callus formation (Fig 2.1.1-4). Furthermore, positioning of the cortical side of the bone grafts opposite to the plate increases the biomechanical strength of the construct. Three screws on both sides of the nonunion provide sufficient stability.
Even large defect nonunions can be bridged by multiple iliac autogenous cancellous bone grafts. Vascularized grafts are not necessary, combined fixation techniques allow for a stable internal fixation (Fig 2.1.1-5).
Related posts:
Wave plate fixation of an atrophic midshaft clavicular nonunion
Infected nonunion of the clavicle
Anteroinferior plating of midshaft clavicular nonunions
Lateral clavicular nonunion with torn coracoclavicular ligaments
Lateral clavicular nonunion with intact coracoclavicular ligaments
Midshaft clavicular nonunion
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