The goal of this study was to report the number of CPT cases that achieved union at final followup, number of refractures, the secondary procedures required to achieve union, repair fractures, and/or correct angular deformities, and amount of limb length discrepancy. The natural history of CPT is recalcitrant nonunion, progressive LLD and deformity, and recurrent refracture even after initial union [4
]. The primary objective of treatment for CPT is to obtain union. The secondary objective is to maintain union. In addition, many associated deformities of length and angulation should be addressed in the comprehensive management of CPT. Therefore, unless all patients have reached skeletal maturity, the refracture rate reported is always lower than actual [4
We had no control group in this retrospective study and it is therefore difficult to know exactly which factor of our combined approach was responsible for the healing of CPT. None of the patients in our series had reached skeletal maturity, and the average followup from the index operation was 4.3 years (range, 2–10.7 years). Additional refractures are expected until patients reach skeletal maturity. However, we believe the combination treatment (ie, periosteal grafting, bone grafting, internal rodding, and Ilizarov fixation) provides the best combination of biologic and mechanical properties for healing and is preferable to any of these methods in isolation. The recent addition of pharmacologic management including bisphosphonates and rhBMP is promising and is consistent with our shotgun technique of management.
What is remarkable is that all patients in our study achieved primary union. In comparison, the initial union rate in the EPOS multicenter study using the Ilizarov method was 75.5% (82 of 108 patients) [16
]. In another study, initial union was achieved in 17 of 21 patients [3
]. Using IM rodding alone, unequivocal union was obtained in only 11 of 23 patients [21
]. In two further recent studies on the use of IM rodding, the initial union was achieved in 18 of 21 patients [10
] and four of 12 patients [26
]. The use of BMP with IM rodding failed to achieve union in four of five patients [27
]. Of particular note is that all patients are united at the time of followup and at the time of writing of this manuscript (Tables , ). There is no other series in the literature with such a high maintained union rate. Boero et al. [3
] reported seven of 21 patients with persistent nonunion at the time of review with average age at treatment of 8.8 years (range, 1.3–17 years). Kim and Weinstein [26
] failed to achieve union in three of 12 cases with average age at treatment of 2.5 years (range, 0.5–8.8 years). Ohnishi et al. [32
] failed to achieve union in 15 of 73 using a variety of methods in a Japanese multicenter study in which the average age at treatment onset was 4.6 years (range, 0.9–15 years). Johnston [21
] failed to obtain union in three of 23 and had tenuous or possible nonunion in nine of 23 using IM rodding for a group of patients whose average age at treatment onset was 3.7 years (range, 0.9–9.4 years). Dobbs et al. [10
] had two of 21 cases that did not unite during a long-term followup study in which the average age at treatment was 5.1 years (range, 0.9–11 years).
Refracture in our series occurred in eight of 20 patients (Table ). All were retreated and all obtained union of the refracture site. One to five refractures occurred in 47 of 108 patients treated by the Ilizarov method in the multicenter EPOS study [16
]. Refracture occurred in 12 of 21 patients treated with IM rodding in the Dobbs et al. [10
] study. Most other studies [26
] show similar or higher refracture rates for all the various methods. El-Rosasy et al. [14
] showed the combination of intramedullary nailing with external fixation reduced the refracture rate from 68% (with the Ilizarov device alone) to 29% (IM nailing and external fixation).
The use of the Ilizarov device allows simultaneous correction of leg-length difference and ankle valgus (Table ). The average LLD at the time of review was 0 cm (range, –7 to 3 cm). Five of 20 patients had LDTA outside of the range of 85° to 95° (Table ). Seven had ADTA outside of the range of 75° to 90° (Table ). Some of these ankles might need additional surgery in the future. Since all the patients use protective orthotic devices, the foot and ankle position has not been symptomatic.
As can be seen from the selected group of studies discussed above, all previous methods resulted in recalcitrant CPT in 13% to 50% of cases. All have used one or more parts of the method applied in this series (eg, Ilizarov fixation, bone grafting, IM rodding, BMP, zoledronic acid, limb lengthening). None have combined all these methods or included the use of periosteal grafting.
Some authors suggest the results of treatment are better when the patient is older [3
]. The average age in this series is very young (Table ). Therefore, observing such good results with patients who are so young is even more remarkable.
The pathology of CPT is still unknown. During the past 100 years, a number of theories have been suggested to explain the development of the disease. Pathologic changes in the periosteum are one factor that could explain the pathologic changes in congenital pseudarthrosis of the tibia [17
]. Codivilla [8
] was the first to suggest the use of osteoperiosteal grafting from the sound tibia to provide all the tissues involved in the formation and growth of bone, especially the periosteum. McElvenny [29
] reported a markedly thickened, closely attached periosteum that caused constriction of the bone with subsequent atrophy and pseudarthrosis. The findings presented by McElvenny were echoed by Boyd [4
] and Boyd and Sage [5
], who suggested that CPT was caused by aggressive osteolytic fibromatosis and that those findings had been confirmed by specimens of amputated legs. Blauth et al. [2
] reported the findings of a pathology study of 10 patients with CPT and postulated the thickened periosteum might be caused by myofibroblast overgrowth [19
]. A recent report [17
] suggested the thickened periosteum was caused by neural-like cells that form a tight sheath around the small periosteal vessels, causing narrowing or obliteration of the vessels. This results in disturbance of the blood circulation of the periosteum, which in turn results in impaired oxygen and nutrient supply of the subperiosteal bone with subsequent fracture and recalcitrant nonunion.
There is reason to believe combining BMP and bisphosphonate treatment with zoledronic acid may be a useful adjunct. In a review of CPT, Johnston and Birch [22
] advocated using BMP as an adjuvant treatment in all primary and recalcitrant cases. Despite optimism with the use of BMP, one must also consider theoretical risk of tumorigenesis because BMP stimulates the RAS pathway, which is also a tumor pathway. Patients with CPT have a propensity for both benign and malignant tumors. Although there has never been a report of such a complication, it should be discussed with patients since rhBMP is not FDA-approved for children or for CPT.
CPT is a biological problem as well as a mechanical problem [31
]. Many pathologic studies confirm periosteum plays a key role in the pathogenesis of CPT. Our protocol of combined procedures addresses both mechanical and biologic aspects of the disease, including complete excision of diseased periosteum and the use of combined bone grafting and periosteal grafting with Ilizarov external fixation and IM rodding of both the tibia and fibula to achieve and maintain union.