Is Distraction Bone Block Arthrodesis better than Subtalar Arthrodesis for Malunited Calcaneal Fractures with Subtalar Arthritis? A Retrospective Case Series

INTRODUCTION

Displaced intra-articular calcaneal fractures is a challenging situation to perform and to obtain a satisfactory reduction and internal fixation for optimum results. Inadequate reduction/ mismanagement/conservatively managed displaced calcaneal fracture leads to subtalar arthritis, broadening of heel, loss of hind foot height, and hindfoot malalignment (varus/valgus deformity).¹ The incidence of subtalar arthritis following conservative treatment of calcaneal fracture is reported to be between 27% and 54% in two short-term studies^2,3 and as high as 91% in a 15-year follow-up study reported by Ibrahim et al.⁴ Various symptoms with which patients present due to these associated delayed complications are painful heel, heel widening, loss of heel height, anterior tibiotalar, and peroneal impingement.^5–7 Decreased hindfoot height leads to limb shortening and leads to the lever arm dysfunction of the Achilles tendon, and increased hindfoot width may cause subfibular peroneal tendon impingement. Ankle impingement of any type can also occur after calcaneal fracture, including posterior ankle impingement, which may arise from the bone spike immediately posterior to the depressed posterior calcaneal facet.^8,9 Painful subtalar arthritis from the incongruous joint due to malunited intra-articular calcaneal fractures has been treated successfully with arthrodesis across the joint.¹⁰ Isolated subtalar arthrodesis was considered as effective treatment for hindfoot pathology by Joveniaux et al.¹¹ While Carr et al. described the technique of distraction bone block arthrodesis and demonstrated effective correction of hindfoot malalignment and good clinic-radiological outcome.^10,12 There are no studies comparing the clinical and radiological outcome of in situ fusion vs distraction arthrodesis in the recent literature. The only comparative study for in situ fusion is in 1999 by Huang et al.,⁸ where he had compared the in situ fusion vs sliding corrective osteomy. Is restoration of hind foot alignment possible in all cases and does the restoration of radiological parameters affect clinical outcome needs to be studied. The present study is aimed at comparing the results between the in situ and the distraction group based on clinical scores and radiological parameters. Our hypothesis is clinical results of the distraction arthrodesis is better than in-situ fusion from the available literature.

MATERIALS AND METHODS

This study is a retrospective study of patients who were operated during January 2015 and March 2018 and included all the patients who presented with malunited calcaneal fracture and subtalar arthritis. All patients with previous history of calcaneal fracture, treated either surgically or conservatively, with symptoms of subtalar arthritis and painful subtalar movements and/ anterior and lateral ankle impingement were included for the study. Patients with adjacent joint arthritis, bilateral involvement, and those who had undergone arthrodesis of adjacent joints were excluded from our study.

We had a total of 36 patients who underwent either of the two procedures, in situ or distraction bone block arthrodesis with minimum follow-up of 6 months. All the patients who presented during early study period from January 2015 to November 2016 were operated with in situ fusion and patients during later half December 2016 to March 2018 underwent distraction arthrodesis. This is a retrospective comparison study of two procedures done with all patients during different periods of time, where group I had 22 patients underwent in situ arthrodesis and group II had 14 patients underwent distraction bone block arthrodesis by a single orthopedic surgeon. Preoperative range of movements of the ankle and subtalar joint were assessed using a goniometer. Follow-up was done at 6 weeks, 3 months, 6 months, 1 year, and final follow-up. Functional scores, (hind foot AOFAS), radiological assessment to compare the pre- and postoperative parameters, were done at final follow-up.

RESULTS

In situ group included 17 males and 5 females with mean age of 44 ± 12.99 (range, 24–76), whereas the distraction group had 10 males and 4 females with mean age of 37 ± 9.91 (range, 24–57). Mean follow-up in the in situ group was 19.26 ± 10.66 months and distraction group was 12.91 ± 4.48 months. All patients from both the groups reported better subjective outcome in the operated limb, 24% as excellent, 51% as good, 19% as average, and 6% as poor. All patients achieved levels of independent mobilization without support at an average of 4.5 months. Active dorsiflexion improved from mean of 9° preoperatively (range, 4–17°) to 11° postprocedure (range, 6–16), whereas plantar flexion decreased from mean of 29° (range, 20–37) to 23° (range, 16–26) postoperatively at final follow-up. In the in situ group, two patients had superficial infection with wound gaping in 1, were managed conservatively with a course of oral antibiotic and regular dressings. In distraction group, 1 patient had a superficial infection at the operative site, one had a late collapse but had a good functional result. Functional assessment done using AOFAS scores showed statistically significant improvement postoperatively in both groups when compared to preoperative scores with p value <0.005. In the in situ group, the mean score postoperatively was 73.83 ± 17.33 SD when compared to 80.33 ± 3.65 in the distraction group (Table 1). Although the score improved in the distraction group as with in situ group, the difference was not statistically significant (p value 0.371). Assessing radiological parameters in the in situ group and distraction groups, there was no significant improvement postoperatively as shown in Table 2. All the radiological parameters (Figs 3 to 5) in the distraction group showed better restoration than the in situ group parameters, but the difference was not statistically significant.

DISCUSSION

The most important finding from our study is distraction arthrodesis restored the hind foot radiological parameter better than the in situ fusion; however, there was no significant difference in the clinical outcome of these patients. Treatment modalities for painful subtalar arthrodesis in patients with malunited calcaneal fracture have been widely discussed in the literature.^1,7,14–16 Selecting an appropriate procedure should be catered on the symptoms that are needed to be addressed, such as extent of pain, duration of symptoms, limitations of daily activities, clinical hindfoot malalignment, and hindfoot height loss. In situ arthrodesis has been traditionally used by many surgeons around the world successfully for treatment of isolated subtalar arthritis, but presence of heel widening, gross depression, and malalignment in various planes require additional interventions to alleviate the patients symptoms. Carr et al.¹² reported the technique of distraction arthrodesis in cases of loss of talocalcaneal height, and the procedure has been replicated in several studies since then. Indication for distraction arthrodesis was recommended when the loss of talocalcaneal height (TCH) was more than 8 mm by Myerson et al.,¹⁷ while others have included signs of anterior tibiofibular impingement as the indication.⁸ In our study, mean TCH was more than 8 mm in both the groups, in situ fusions were done in our earlier cases, and later we have moved to distraction arthrodesis in all the cases. Yu Guang-Rong et al.¹⁸ suggested that the vertical sliding osteotomy with subtalar arthrodesis may be needed for the reconstruction of calcaneal thalamus and subtalar arthrodesis.¹⁸ However, none of our cases needed additional calcaneal osteotomy to correct the hind foot deformities.

We observed satisfactory union in both the groups, and we had 100% union in the in situ group, which was similar to the study by Joveniaux et al.¹¹ One case in the distraction group had a late collapse but was asymptomatic and had good functional outcome at 1-year follow-up. Iliac crest autograft was used for all cases of distraction arthrodesis and did not have nonunion. After harvesting tricortical iliac graft, multiple drill holes in the graft was done to improve the chances of bone graft incorporation to the opposing bone surfaces. In bone block distraction arthrodesis, using an interpositional graft, concern has been raised pertaining to union of the intervening bony surfaces.¹⁹ The union rate of the arthrodesis varied from 90 to 100% in various studies.²⁰ A few studies have reported a rate of union to be 100%^5,21–27 which is similar to our series, where subtalar fusion is achieved by distraction arthrodesis. Allograft usage has demonstrated nonunion as shown by Trnka et al. and hence generally not preferred.¹⁹ Lateral wall exostosis is commonly seen in calcaneal malunion due to height collapse, and its removal to restore the calcaneal width and peroneal tendon impingement is advocated. Many authors performed subtalar distraction arthrodesis using the longitudinal posterior approach just lateral to the Achilles tendon,^28,29 where the lateral wall exostosectomy/excision was not addressed, while others^12,30 performed through posterior approach. In our series, we preferred to use the lateral approach to easily perform excision of the lateral wall and to ensure adequate peroneal tendon release in all our cases. In all, 5.40% of patients had reported paresthesia over the lateral border of foot in distraction group at initial follow-up which recovered at final follow-up; this is in accordance with literature that has reported 0 to 17% incidence of sural nerve neuralgia.^12,14,19,27 The present study observed good results and reproducibility with the extended lateral approach, whereas literature has shown use of posterior approach in few studies.^19,27 The comparison between the in situ and distraction group showed higher AOFAS ankle-hindfoot score postoperatively in the distraction group, but the difference was not statistically significant. Further, distraction arthrodesis restored the hindfoot alignment better than the in situ arthrodesis. However, these anatomical improvements did not seem to have clinical benefits which was also observed by Joveniaux et al.¹¹ Clinical outcomes obtained with distraction subtalar arthrodesis are similar to those obtained with in situ subtalar arthrodesis.^5,15,21,31 Several studies did not show statistical correlation between the heel height and the global outcomes.^15,17 Higher incidence of malunion and non-union has been reported with distraction arthrodesis in the literature¹⁹ which is contrary to our study, where we had 100% union in both the groups. There are few limitations in this study, where sample size is small, follow-up is shorter, and it is a retrospective study. Prospective randomized trials are needed to clearly differentiate the superiority of one technique over the other.

CONCLUSION

Distraction arthrodesis in malunited calcaneal fractures with painful subtalar arthritis shows restoration of radiological parameters better compared to the in situ group; however, there is no significant difference in functional outcome.

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