Guided growth with tension band plate or definitive epiphysiodesis for treatment of limb length discrepancy?

In children with open epiphyses and predicted leg length discrepancy (LLD) at maturity between 2 and 5 cm, epiphysiodesis is the treatment of choice [1]. Phemister was the first who published an open fusion technique of the growth plate [2]. Over the years, less invasive techniques for irreversible growth arrest have been described and are most commonly performed percutaneously [3, 4]. Potentially reversible epiphysiodesis techniques became more and more popular [5, 6]. A guided growth technique with tension band plates—so-called eight-plates—first described by Stevens et al. for angular correction received also popularity for correction of LLD [7]. Effective correction of LLD with tension band plates has been reported in two studies [8, 9].

Recently, however, the efficiency of epiphysiodesis for LLD correction with tension band plates was doubted and irreversible epiphysiodesis was favored in several studies [10‐12].

The purpose of the present study was therefore to find out if definitive percutaneous epiphysiodesis is superior to tension band plate epiphysiodesis for LLD correction.

The study was approved by the institutional review board and by the local ethics committee.

Data from all patients undergoing epiphysiodesis for correction of LLD between January 2006 and December 2012 was collected retrospectively. Study inclusion criteria were LLD correction with epiphysiodesis and a minimum follow-up of 12 months after surgery. Patients with additional correction of angular deformities, skeletal dysplasia, malignancy, Blount disease, or follow-up less than 1 year were excluded.

Skeletal age was analyzed according to the method of Greulich and Pyle [13]. Expected LLD at maturity had to be at least 2 cm as an indication for surgery.

Thirty-eight patients were included in the study, with 21 in the DE group and 17 in the TE group. The average age at surgery was 13.6 years. There were no statistical differences between the groups, apart from the location around the knee where surgery was performed (p = 0.021) and sex (p = 0.02). Detailed patient demographics are illustrated in Table 1.

Etiologic factors of LLD are listed in Table 2.

The average final follow-up was at 578 days. The reduction of the LLD in 12 months was 5.7 mm in patients treated with TE and 8.4 mm with DE, respectively. This difference was, however, statistically not significant (p = 0.22). The percentage of improvement after 1 year was 26% in the TE group and 36% in the DE group. Detailed results at 1-year follow-up are depicted in Table 3.

In 27 patients, the reduction of LLD was analyzed at 2-year follow-up. Patients treated with TE (n = 15) had a reduction of 12.2 mm (55% improvement) and those treated with DE (n = 12) of 17.9 mm (77% improvement), respectively. Again, these differences were not statistically significant (p = 0.16).

Individual results of tibial and femoral length correction did not show any statistically significant differences at 1- and 2-year follow-up as well (Table 4). Interestingly, after 2 years, tibial length correction was better in the TE group than in the DE group (p > 0.05).

In the present study, both evaluated epiphysiodesis techniques showed sufficient LLD correction. However, as supposed in previous studies, LLD correction with tension band plating seems to be slightly less effective compared to definitive epiphysiodesis. Nevertheless, the differences of 5.7 mm versus 8.4 mm after 1 year and 12.2 mm versus 17.9 mm of LLD correction after 2 years were not statistically significant in the present study. In the individual analyses of tibial or femoral epiphysiodesis, differences are even less distinct (Table 4).

Patients treated with TE had a higher revision rate in our study. Two patients (11.7%) had to undergo a second surgery because of malalignment, whereas no patient had that problem in the DE group. In both groups, one patient underwent secondary DE due to insufficient LLD correction after 1 year (5.9% vs. 4.8%). In these patients, only epiphysiodesis of one epiphysis around the knee was performed initially. As a consequence, additional epiphysiodesis of the untreated epiphysis was necessary to correct LLD.

One further issue worth to discuss is the fact that all patients after TE were scheduled for a second surgery to remove the metal. On the one hand, the rate of additional surgery should be as minimal as possible. On the other hand, the principle of TE as a guided growth technique gives the possibility to react in case of corrected LLD and avoid overcorrection. Furthermore, one can react in cases of malalignment with partial metal removal or additional unilateral tension band plating.

This present study represents one of the largest reported series in the literature comparing TE with DE. However, one weakness is the limited number of patients.

Further limitations of the current study should be acknowledged. The study was retrospective and patients were not randomized or matched. However, only one published study in the literature with a retrospective design as well had a higher number of patients included [8]. That study did not give any results in terms of mechanical axis deviation, though. Bayhan et al. included 24 patients in an eight-plate group (TE) and 48 patients in a percutaneous group (DE). In their study, both groups showed to be effective for LLD correction. However, the percentage of improvement was significantly lower in the eight-plate group with a p value of 0.031 (41 vs. 58%), which was calculated as the initial minus final discrepancy, and the result was divided by the initial discrepancy. There was, however, no evaluation of tibial or femoral treatment individually in that assessment. In the individual analysis of femoral and tibial correction, no significant differences were found in that study. In both groups, final LLD below 2 cm was reached, with an average correction of 12 mm in the eight-plate group and 16 mm in the percutaneous epiphysiodesis group. These results are very similar to our results with final LLD correction of 12.2 mm in the TE groups and 17.9 mm in the DE group, respectively.

Some authors of further studies formulated the lower efficiency for LLD correction observed with eight-plate epiphysiodesis more clearly. Gaumétou et al. concluded that growth arrest observed after eight-plate technique was unpredictable and lower than that achieved with percutaneous epiphysiodesis using transphyseal screws (PETS) [10]. However, there was no control group in the study. Thirty-two patients were included and an expected growth arrest was calculated. Tibial efficiency with 42% was lower than femoral efficiency with 68% of expected growth arrest at final follow-up at 18 months.

Stewart et al. published a study on 27 patients with 11 treated with dual eight-plate and 16 treated with a physeal ablation technique, similar to the DE group in the present study [12]. Statistically significant difference was shown with 15.5 mm LLD correction in the ablation group compared to 4 mm in the eight-plate group. However, the study had major limitations that were published in a letter to the editor of Kaymaz et al. [15]. Technical and methodological errors are listed in that article.

A further limitation of the present study was that no individual analysis regarding etiologic factors was performed. However, the etiologies of LLD in both groups are listed in Table 2 and are considerably similar.

As a result of the inferior LLD correction with higher complication and revision rate, we personally do not use tension band plates anymore for that indication in our department, except in very rare cases of combined complex angular and length deformities in young children.

As reported in earlier studies, temporary epiphysiodesis with tension band plating seems to correct LLD less powerful compared to definitive percutaneous epiphysiodesis. However, in the present study, the differences of LLD correction were not statistically significant. Sufficient LLD correction to an average of below 2 cm could be reached in both groups, though. Definitive epiphysiodesis had a lower revision rate (4.8% vs. 17.6%). We do not recommend the use of tension band plates for LLD correction due to inferior correction with higher complication and revision rate.