Mid-term outcome following revision surgery of clavicular non- and malunion using anatomic locking compression plate and iliac crest bone graft

The presented study collective consists of 14 consecutive patients with a mean age of 41 years and a male–female ratio of 4:3 comparable to other outcome studies concerning age and gender [7, 15, 16]. 9 patients developed non- or malunion despite of previous operation of their acute clavicle fracture in external hospitals. Failure of the initial surgical treatment was most commonly present in case of a biomechanically insufficient fixation as shown in Fig. 4: Patient No. VI was initially treated by a non-locking plate fixation with only two screws in the lateral fragment and one screw in the fracture gap. Therefore the strong moments of tensions and bending as well as torsional forces impacting on the clavicular midshaft led to failure of the plate fixation with secondary dislocation and migration of one screw. The findings of Gilde et al. [17] that non-locking plates result in a higher non-union rate in comparison to locking plates in the treatment of midshaft clavicular fractures confirm the relevance of angle stable implants. In addition locking plates lead to promising results even in high demanding clavicular non-unions such as long standing non-unions with poor bone stock [18] and non-unions of the distal clavicle [19].

Major complications in the treatment of clavicular non- and malunion as performed in the presented study contain loss of plate fixation [20], persistent non-union and soft-tissue complications [5]. In the presented study none of these complications were observed. However a total complication rate of 21% is rather high. Anterior iliac crest bone grafting is a very common surgical procedure in patients suffering from non-unions, delayed fracture union or traumatic bone loss [21] to obtain a high qualitative and quantitative bone graft. Common complications contain pain, irritation of the nerve and infection at the donor site. Secondary fractures of the anterior iliac spine, as observed in the current patient collective, are well-known but very rare and only case reports are described in the literature [22]. These patients present with circumscribed pain and loss of range of motion most commonly following an overload of the inserting muscles. In case of non-displaced fractures conservative treatment can lead to bony union without functional residuals as described for patient No. IV. However, in a few cases presenting with severe displacement such as patient No. VIII plate fixation of the anterior iliac spine is indicated and was performed so as described previously. To avoid secondary fractures a sufficient safety distance of at least 2 cm should be maintained in anterior iliac bone graft harvesting [23].

In 5 of 14 enrolled patients elective implant removal was performed by the patients’ explicit request because of complaints such as pain if carrying a heavy backpack or sensitivity to weather changes. In the current literature, routine removal of metal implants remains a controversial issue with a lack of evident guidelines in the surgical treatment of acute clavicle fractures as well as of clavicle non- or malunions. Due to the typical surgical risks and complications, implant removal should only be performed in symptomatic patients after a detailed discussion of potentially available treatment options. Compared to other bony sites of the upper limb, removal of metal implants is most commonly performed in the clavicle [24], most likely because of the prominent subcutaneous position of the implant especially in athletes with poor soft tissue coverage. In our collective, in 5 patients removal of implants was performed at the earliest time point two years after surgery and only after integration of the bone graft and bony union had been proven by CT. However, one patient presented five weeks after elective implant removal with a re-fracture of the clavicle. She reported a sudden onset of pain in her shoulder during swimming. Although swimming constitutes a questionable adequate trauma we recommend to restrain from sport activities for at least 8 weeks after implant removal. However, evidence for a reasonable recommendation is lacking and benefit as well as risks of implant removal have to be investigated in further studies.

Follow-up evaluation was performed during the routine follow-up examinations at the outpatient clinic by assessing the Constant Score. The original Constant Score values were converted according to Gerber et al. [13] to receive a normative age- and sex-specific relative Constant Score. At a mean follow-up of 27 months the mean relative Constant Score significantly improved by 21 points in the presented patient collective (p < 0.05; see Table 1). The functional results are comparable to other authors who operatively treated non- or malunions of the clavicle. Jubel et al. [7] reported a relative Constant Score of about 95% at a follow-up of 18 months after intramedullary nailing of clavicular non-unions. The authors state that performing surgery without using an iliac crest bone graft constitutes a relevant advantage of intramedullary nailing. However, the requirement of a bone graft is not depending on the used implant but rather on the local bone defect size. In addition intramedullary nailing leads to inferior biomechanical rotational stability in comparison to plate fixation [25]. McKee et al. [20] published the results of non-locking plate fixation in 15 patients suffering from malunions of the clavicle after initial conservative treatment. The authors found a significant improvement of pre- to postoperative self-assessed DASH scores. Nevertheless, in their study loss of plate fixation was seen in one patient and another patient developed a non-union. Hence we consider intramedullary nailing or single non-locking plate fixation in non- or malunions of the clavicle with a significant clavicle shortening in comparison to the healthy contralateral side as an insufficient approach due to the remaining instability allowing for movement with an increased risk of loss of fixation or persisting non-union. In the presented patient collective radiographically bony union occurred in all patients after a mean interval of 8–18 weeks in conventional radiography. In case of implant removal a preoperative computed tomography was performed. However one patient presented five weeks after elective implant removal with a re-fracture of the clavicle. Therefore computed tomography cannot guarantee bony consolidation even in asymptomatic patients.

The major drawbacks of the presented study are its retrospective nature without the assessment of a control group and the low number of included patients. However the most studies focusing on the outcome of clavicular non- or malunions contain a comparable number of cases due to the general low incidence of non-unions of the clavicle. The low incidence is also the reason that we found no comparative study published in the literature. Another drawback presents the postoperative rehabilitation that was performed on an outpatient basis. Thus it was not performed in a standardized way and although physiotherapy should be done according to a standard protocol we cannot guarantee the patient’s compliance.