Pseudarthrosis of rib fractures is rarely observed, and, to our knowledge, only nine cases have been described in the English-language literature1-9. In one case the suggested treatment consisted of restriction of movement. In three cases resection of the pseudarthrosis was described, and in two cases an association with a synovial cyst was found.
We present three cases in which pseudarthroses of rib fractures were treated with open reduction and internal fixation with use of locking compression plates. All patients were informed that data concerning their cases would be submitted for publication, and they consented.
Case 1. A fifty-six-year-old man experienced thoracic trauma eight months prior to the time of presentation. He sustained fractures of the eighth, ninth, and tenth ribs on the left side. A thoracic drain was placed to treat a pneumothorax, and the rib fractures were treated nonoperatively. Eight months after the injury, the patient complained of persistent pain, especially during deep inhalation and coughing. The patient had a visual analog score of 6 (of 10) for pain. Physical examination revealed a painful area on the left side of the thorax. Conventional radiography showed a pseudarthrosis of the ninth rib; the fractures of the eighth and tenth ribs were consolidated. A computed tomography scan confirmed the diagnosis and suggested interposition of tissue within the fracture of the ninth rib. Because of the duration of the complaints and the lack of improvement with nonoperative measures, osteosynthesis of the ninth rib was performed. Interposition of muscle tissue within the fracture was confirmed during the operation, and the tissue was removed. Osteosynthesis was carried out with use of a small-fragment locking compression plate with self-drilling unicortical screws (Synthes; West Chester, Pennsylvania). Intraoperatively, the patient had development of a pneumothorax, for which a pleural drain was introduced. After a follow-up period of nineteen months, the patient was completely pain-free, with a visual analog scale score of 1.
Therapeutic Considerations
While planning the first operation, we presumed that the shortest self-drilling locking head screws would not penetrate the second cortex of the rib sufficiently to create a pneumothorax. In practice, this proved otherwise. Because of this complication, we developed a different technique involving the use of the locking compression plate drilling guide with an integrated drill with limited penetration (LCP Universal Drill Guide 3.5, item number 323.505; Synthes) (Fig. 1).
This readily available device enables controlled drilling to a depth of 6 mm. In order to evaluate whether this technique would work in practice, we performed a laboratory test on a human cadaver. Three ribs were exposed on the right side of the thorax in the midaxillary plane.
We tested three different operative techniques of reconstruction with a locking compression plate. On the upper rib, the first technique was performed with normal manual pre-drilling of both cortices and insertion of non-self-drilling (green) unicortical screws. Care was taken not to penetrate the pleura. On the middle rib, the shortest self-drilling (blue) locking head screws were inserted without any pre-drilling.
On the last rib, our third technique was used. With use of the previously described locking compression plate drilling guide (item number 323.505), holes were drilled to the maximum depth permitted by the drill (6 mm). Subsequently, the shortest self-tapping screws (10 mm) were inserted.
The three ribs were then carefully extracted, with the parietal and visceral pleurae being left intact. Inspection of the dorsal side of the first two ribs showed penetration of the parietal pleura at all screw locations. Furthermore, injury to the upper part of the right lung, due to the manual pre-drilling, was revealed. The third rib showed no parietal pleural penetration; at most, there was a translucent subpleural spot where the drill of the locking compression plate guide had reached subpleural tissue. As a result of these findings, two subsequent patients with pseudarthrosis of the ribs were managed with the new technique.
Case 2. A forty-four-year-old man experienced thoracic trauma six months before the time of presentation. He sustained seven rib fractures (involving the third through ninth ribs) on the left side. The patient experienced persistent pain on mobilization after nonoperative therapy. He had a visual analog scale score of 7 (of 10) for pain. Compression of the entire left side of the thorax during physical examination was painful. Conventional radiography revealed pseudarthrosis of the third, sixth, seventh, eighth, and ninth ribs; the fourth and fifth ribs were healed. Because of the severity and persistence of pain, osteosynthesis was performed on the seventh, eighth, and ninth ribs. The surgical approach was through one incision. During the operation, hypertrophic pseudarthroses with completely mobile fracture ends were seen at all three levels. Osteosynthesis was performed with use of three small-fragment locking compression plates. The locking compression plate drilling guide with an integrated drill with limited penetration was used to prepare drill-holes, which were filled with non-self-drilling unicortical screws. The postoperative course was uneventful, and, after twenty-six months of follow-up, the patient was completely pain-free, with a visual analog scale score of 1 for pain.
Case 3. A forty-two-year-old man experienced high-energy thoracic trauma with multiple rib fractures (involving the fourth through tenth ribs) on the left side. During the outpatient clinic visits, the patient complained of persistent pain in the left flank. He had a visual analog scale score of 7 (of 10) for pain. A three-dimensional computed tomography reconstruction revealed pseudarthroses of the sixth, seventh, and eighth ribs (Fig. 2-A). Because of the patient's complaints of persistent pain, osteosynthesis of the sixth, seventh, and eighth ribs was performed. Through one incision, the three hypertrophic pseudarthroses were identified and osteosynthesis was performed with use of three locking compression plates, each with six non-self-drilling unicortical screws, after drilling with use of the drill guide with the limited-penetration drill-bit. The postoperative course was uneventful. Eighteen months after the placement of the three locking compression plates, the patient still experienced some discomfort with certain movements, probably because of the hardware. However, the character of the pain differed completely in comparison with the preoperative pain. The patient had a visual analog scale score of 3 for pain. A three-dimensional computed tomography scan showed complete consolidation of the fracture sites (Fig. 2-B). Because of the discomfort, the implants were removed. The patient then had a visual analog scale score of 1 for pain.
Pseudarthrosis of the rib is rare; therefore, nonoperative measures seem warranted in most cases. However, the cross-sectional surface area of a single rib is not greater than 60 square mm10. Thus, in some cases a sufficiently large contact surface may not be present to allow the healing process to occur. Given that ribs move an average of 25,000 times per day with respiration, it is surprising that pseudarthrosis of the ribs is not seen more frequently. It is possible the phenomenon is not often recognized or is asymptomatic.
The first patient in the present study had an isolated pseudarthrosis of one rib, with consolidation of the adjacent ribs. These findings suggest that stability was not an issue, which was supported by the observation that the pseudarthrosis was due to soft-tissue interposition.
Both of the latter two patients originally had seven rib fractures with five (Case 2) and three (Case 3) hypertrophic pseudarthroses. The hypertrophic character of the nonunions suggested a problem with fracture stability. Thus, stabilization through osteosynthesis seemed to be a logical approach.
The diagnosis of pseudarthrosis of rib fractures should be considered when a patient complains of persistent pain during movement and/or deep inspiration. The diagnosis can be confirmed by means of conventional radiography; however, in our opinion, a thoracic computed tomography scan is more accurate for confirming the diagnosis and for providing essential information for preoperative planning. With conventional radiography, it is difficult to determine the exact location of the pseudarthrosis or pseudarthroses; however, this is of great importance when open reduction and internal fixation of three ribs is planned through one incision.
Because of the unique anatomy of the rib, there are specific challenges to internal fixation. The rather flat structure of the rib provides less screw purchase and could present some difficulty in achieving rigid osteosynthesis, especially if one prefers to perform unicortical fixation in order to reduce the risk of pleural penetration. The use of a locking plate with angled screws instead of a standard non-locking plate is preferable because it is the most rigid osteosynthesis system available11.
In the case of our first patient (Case 1), we had thought that the shortest unicortical locking compression plate screws would be short enough to prevent a pneumothorax, but they were not. In the cadaver study, it was confirmed that even the shortest self-drilling unicortical screws (10 mm) will penetrate the second cortex of the rib. The use of the locking compression plate drill guide with controlled limited penetration (item number 323.505; Synthes) seemed to be a safe method in the cadaver study as no penetration of the pleural tissue was seen. Our other two patients (Cases 2 and 3) were managed with this new technique, and in both cases there were no perioperative or postoperative complications and the pseudarthroses healed. This finding supports our hypothesis that stabilization of a symptomatic pseudarthrosis should be carried out and that the technique presented here can result in safe osteosynthesis and bone healing. 