There have been numerous reports of the management in regarding to various displacement of S-H Ⅱ distal tibia physeal fractures [1, 3, 8, 10, 11, 12]. However, there has been sporadic report composing exclusively of severe displaced fracture. To the best of our knowledge, this study represents the largest series, in one institution, involving S-H Ⅱ distal tibia fractures alone with initial displacement of > 3mm treated by ORIF.
For these fractures, several retrospective cohort studies [8, 9, 16, 17] and one systematic review [18] demonstrated that there was no significant difference in PPC rate between open reduction and closed reduction. Some of these studies, however, were performed among varying displacement of the fractures. Moreover, there was a lack of random controlled study for displaced fractures. Recently, a magnetic resonance imaging study showed that periosteum was entrapped in all 15 displaced S-H Ⅱ distal tibia fractures [19]. And up to 60% of cases had residual displacement > 2mm after closed reduction [11]. We attempted to minimize reduction attempts prior to operation and remove the entrapped periosteum and apply gentle manipulation during operation so as to avoid further damage to the physis [16, 20]. The incidence of PPC was 29.4% in our series, which was less than that reported in literatures. Russo et al. [8] showed a 53% PPC rate in S-H Ⅱ fractures with displacement > 2mm treated with ORIF after failure of closed reduction.
Previous studies have shown that multiple factors were attributable to PPC, including initial or residual displacement [1, 6, 11, 16, 21], mechanism of injury [9, 10, 22], age at injury [16], reduction attempts [1, 14]. In our study, we found no significant correlation between the rate of PPC and mechanism of injury. This may be associated with the relative less proportion of PER that was more susceptible to PPC [9, 10, 22]. Similarly, no significant correlation between PPC and the energy of injury was found. Generally, it was thought that high-grade injury to the physis was associated with the occurrence of PPC [1, 11]. Margalit et al. [11] categorized falls from ≥ 1.5m or a motor vehicle accident as high-energy injury and demonstrated that patients with high-grade injury had 12 times greater of PPC. In our series, we categorized falls from ≥ 1m or motor or e-bike vehicle accident as high-energy injury, from which the growth plate may not suffer sufficient force.
Dias and Tachdjian [15] emphasized that the abnormal force which caused the injuries would sum and such injuries always occurred in a sequence of grades. In our series, we found that the amount of initial displacement in patients with associated fibula fracture was greater than that with intact fibula. Although Spiegel et al. [21] found no association between associated fibula fracture and PPC, we did find significant association between the rate of PPC and associated fibular fracture, which was in accordance to previous literatures [2, 5, 17]. We speculated that injuries with associated fibula fracture may lead to more severe damage to the tibial growth plate than that with intact fibula.
The timing of surgery for physeal fracture is of paramount importance. Petratos et al. [23] suggested that reduction should be performed within one day of damage and the probability of growth arrest will be six fold greater, if the fracture was treated beyond 24 hours. In the present study, the mean interval was delayed to 3.7 days after injury due to significant swelling of the ankle. However, there were two patients with varus deformity of the ankle who were treated on the sixth and ninth day after injury. Given the rarity of the deformity, we cannot conclude whether this isolated case was due to the delayed reduction or not. But we think the earlier the reduction, the lower rate of PPC.
Although we have paid more attention to the displaced S-H Ⅱ fractures, the incidence of PPC, as shown in our study, is still higher than anticipated. We thought this may be due to the shearing force on the Kump’s pump of the physis or the crushing force on the physis at the time of the injury [24].
A limitation of our present study was only a retrospective cohort study. A randomized controlled study should be performed to look at displaced fractures treated surgically vs non-surgically to investigate the risk factors of PPC. Another limitation was less length of follow-up. The average length from injury to diagnosis of PPC was 7 months, even two years after injury [5, 8]. Therefore, the patients with S-H Ⅱ distal tibia fractures should be followed for at least one year to identify the PPC early.
In conclusion, open reduction internal fixation is beneficial to reduce the risk of PPC for displaced S-H Ⅱ distal tibia physeal fractures. The presence of associated fibula fracture plays an important role in the fracture outcome.