Nonunion of the Fractured Clavicle: Evaluation, Etiology, and Treatment

Surgical treatment

Indications

The main indication for surgery is symptomatic nonunion. Pain at the nonunion site is the most frequent symptom and thus the most common reason for operative intervention. Static or progressive neurovascular compromise is another indication for surgery, as well as extremity dysfunction due to ptosis, stiffness, or weakness.

Procedure Options

The various procedures can be divided into two main categories: salvage and reconstructive.^[1] Salvage procedures attempt to alleviate symptoms or deformities without achieving bone union. Reconstructive procedures, however, are designed to achieve bone union. Within each category, there are multiple procedures.

Salvage procedures involve removing a bony prominence or performing a partial or total claviculectomy to provide relief from painful grating or to release entrapped neurovascular structures. Abbott and Lucas^[38] pointed out that the middle third of the clavicle may be removed without significant disability as long as the distal and proximal portions are left intact. Rowe^[5] noted that removal of the entire clavicle results in a "surprisingly good functional and cosmetic appearance" but stated that this should be done only after a patient has had several unsuccessful bone-grafting procedures and is "sufficiently" disabled. Connolly and Dehne,^[34] however, wrote that resection of the midclavicle should be avoided because it is likely to lead to delayed problems. They stated that patients in general are not satisfied with their result or appearance after resection. Overall, taking into account the important functional role of the clavicle and the successful reconstructive options available, an attempt should be made to achieve bone union in an anatomic position for nonunited symptomatic clavicular fractures.

Reconstructive procedures include a wide array of fixation methods for the treatment of clavicular nonunions, ranging from external fixation^[18] and threaded and unthreaded pins^[11,39,40] to plate and screw osteosynthesis.^{[12,15,19,20,21,41,42,43,44,45]} Schuind et al^[18] used a Hoffman external fixator (Howmedica, Rutherford, NJ) to treat both acute fractures and nonunions and had a 100% union rate. Two pins were placed in the medial fragment in an ascending anterior-posterior or almost horizontal direction to avoid the pleural dome, and two pins were inserted in the lateral fragment in a superior-inferior and anterior or almost vertical direction. The external fixator was used for an average time of 51 days. According to Schuind et al,^[18] indications for this type of fixation are an open fracture or a septic nonunion, in which the risk of deep infection is high if internal fixation is used.

Another form of surgical treatment is intramedullary pin fixation and autogenous bone grafting. Boehme et al^[15] described a technique in which a skin incision is made in the Langer line, centered directly over the nonunion site; a modified Hagie pin (Zimmer, Warsaw, Ind) is inserted into the intramedullary canal after excising the fibrous nonunion. The pin is drilled from the nonunion site out through the intra-medullary canal of the distal fragment. A small skin incision is made over the pin at the posterolateral aspect of the shoulder. The pin is then retracted from the clavicle until its end is at the level of the nonunion site. The fracture is then reduced, and the pin is drilled across the fracture site and into the medial fragment. The tip of the pin is left palpable in the subcutaneous tissue laterally to allow for its removal under local anesthesia after the fracture is healed. Autogenous bone graft is then placed around the nonunion site.

Boehme et al^[15] achieved a 95% healing rate in 21 patients using the preceding technique. Capicotto et al^[40] obtained a 100% union rate with a similar procedure using Steinmann pin (Richards, Memphis, Tenn) fixation. Boehme et al^[15] noted that the advantages of intramedullary pinning over other forms of fixation, particularly plate and screw osteosynthesis, include a cosmetically acceptable incision; less dissection of the soft tissues; and, after healing, easy removal of the pin through a small incision under local anesthesia. In addition, the intramedullary pin is a load-sharing device, as compared with plates and screws, which are load-bearing devices. Therefore, osteoporosis (which occurs under a plate as a result of stress shielding) is less severe with an intramedullary pin, and the likelihood of refracture through osteoporotic bone after hardware removal is diminished. One disadvantage of this technique, however, is the lack of rotational control with the pin.^[12,20] Boehme et al^[15] recognized this, and in their early postoperative regimen, they limited forward flexion to a maximum of 90° to "eliminate" rotational forces. Another disadvantage of pin fixation is the potential for pin breakage and pin migration, which results in serious neurologic and pulmonary complications.^[46,47,48]

Connolly and Dehne^[34] described a technique using Knowles pin (DePuy, Warsaw, Ind) fixation, which the authors believe is particularly suitable for hypertrophic nonunions. A small Knowles pin is inserted from the anterior cortex of the medial fragment into the lateral fragment under fluoroscopic guidance. According to the authors, the Knowles pin locks against the anterior cortex and permits good fracture fixation and compression. One main advantage of this technique is that, as in intramedullary pin fixation, there is minimal periosteal stripping. Advantages over intramedullary pin fixation include avoidance of the often difficult placement of intramedullary pins because of the sigmoid shape of the clavicle and avoidance of the loosening and migrating of Steinmann pins.

The final method of fixation is plate and screw osteosynthesis (Fig 3). Edvardsen and Odegard^[41] described a technique consisting of debridement and trimming of the bone ends, placement of a cortical bone transplant posteriorly and metal plate anteriorly, and fixation of the plate to the clavicle and cortical bone transplant with screws. A 100% union rate was achieved in 6 patients with posttraumatic nonunion. With the cortical bone graft posteriorly and plate anteriorly, the construct is stable, but an extensive amount of soft tissue stripping anteriorly and posteriorly is needed. Manske and Szabo^[12] treated 10 nonunions with an AO 3.5-mm dynamic compression plate (Synthes, Paoli, Penn) and iliac crest cancellous bone graft. Radiographically, all the clavicles united at an average of 19 weeks after surgery, and all the patients had full, painless range of motion.

Jupiter and Leffert^[20] reported on an 89% union rate after plate fixation and bone grafting in 18 nonunited fractures of the middle third of the clavicle. The authors emphasized the importance of restoring the normal length of the clavicle because shortening can cause abduction weakness and can increase the moments and forces at the site of the fracture.^[16,20] Seiler and Jupiter^[42] specifically addressed the restoration of clavicular length in a more recent study; they used intercalary tricortical iliac crest bone grafts to treat clavicular nonunions with bony defects. Preoperatively, the authors obtained a view of the contralateral clavicle to establish the normal length of the clavicle, and they determined the size of the bone graft by comparing the anteroposterior radiographs of each clavicle. The nonunion site was debrided, and the medullary canals were opened medially and laterally with a drill bit. They procured a tricortical iliac crest that was 1.5 times larger than the calculated defect. The graft was then placed in the defect and secured to the medial and lateral fragments with a limited contact dynamic compression plate, compressing both the medial and lateral junctions. The authors reported union in all eight patients treated with this technique within 3 months of surgery. Olsen et al^[21] also emphasized the importance of reestablishing native clavicular length. These authors, however, just used autologous cancellous bone graft to fill the defect rather than a tricorticocancellous graft.

More recently, Ballmer et al^[49] emphasized the importance of restoring clavicular length. These authors treated 37 delayed union and nonunion fractures with decortication, plate osteosynthesis, and bone grafts, and they achieved a 95% union rate. Nine patients required tricorticocancellous grafts to restore clavicular length. The authors' indication for using the tricorticocancellous graft was clavicular shortening >1.5 cm compared with the contralateral clavicle.

Boyer and Axelrod^[45] described a technique that entailed shortening the clavicle. The nonunion is excised by cuts at 45° to the long axis of the clavicle, and either a pelvic reconstruction or dynamic compression plate with a lag screw (to provide interfragmentary compression) is used for fixation. Cancellous bone is then placed at the nonunion site. The authors stated that their technique respects AO principles for the treatment of nonunions, allows early mobilization, and minimizes morbidity at the donor site (ie, cancellous bone graft is procured rather than tricorticocancellous graft). In their study, all seven patients with clavicular nonunions healed and returned to normal function. The average reduction in length of the clavicle was 1.5 cm. However, according to the authors, the resultant lack of restoration of the shoulder width proved to be cosmetically acceptable and gave excellent function.

The final issue for plate and screw fixation is the type of plate used. Bradbury et al^[44] compared the results of an AO dynamic compression plate (Synthes, Paoli, Penn) and an AO pelvic reconstruction plate for treatment of clavicular nonunion. The authors reported a 97% union rate (31 of 32 nonunions) and noted no significant differences between the two plates. They stated, however, that the reconstruction plate was much easier to contour to the sigmoid shape of the clavicle.

Mullaji and Jupiter,^[19] on the other hand, prefer a 3.5-mm low-contact-dynamic compression plate (LC-DCP). The authors reported a 100% union rate in six patients treated with the LC-DCP. Valuable features of the LC-DCP include a structured under-surface that preserves the blood supply beneath the plate, avoidance of stress risers after implant removal, and oblique undercuts to the screw holes that allow for insertion of lag screws up to an angle of 40°. Also, the plate is made of titanium, which is twice as flexible as steel, thus rendering it less prone to fatigue failure when used to span a defect. A feature that is specifically valuable to treatment of clavicular nonunions is the uniformly placed screw holes without a solid middle section, which facilitates introduction of a screw or screws into the intercalary bone graft. Also, the uniform bending stiffness of the plate allows easier contouring in multiple planes, important in the clavicle because of its complex shape. Finally, the LC-DCP has universal screw holes that allow compression in either direction and thus permit compression of the intercalated graft to both the medial and lateral fragments.

Overall advantages of plate and screw osteosynthesis over other methods of fixation include excellent control of rotation and the ability to restore the normal length of the clavicle. Also, according to Jupiter and Leffert,^[20] the apex of deformity in a clavicular nonunion is superior; therefore, a plate applied to the superior surface can act as a tension band, which enhances compression across the fracture. Disadvantages to plate fixation include the need for wider exposure and increased periosteal stripping, which can disturb the blood supply to the healing fragments. Also, a larger exposure is required for hardware removal, necessitating another surgical procedure. The potential for refracture after plate removal is increased because of osteoporosis below the plate and stress risers at the empty screw holes (Fig 4).

J South Orthop Assoc. 2000;9(1) © 2000  Southern Medical Association

Cite this: Nonunion of the Fractured Clavicle: Evaluation, Etiology, and Treatment - Medscape - Mar 01, 2000.