Osteotomies combined with soft tissue procedures for symptomatic flexible flatfoot deformity in children

Background: The indications for surgery, timing, and procedure in children with flexible flatfoot deformity remain controversial. For marked deformities, combined procedures are preferred to correct multiple plane deformities. Thus, this study aimed to evaluate the outcomes of osteotomies combined with soft tissue procedures in children with flexible flatfoot aged 9-14 years. Methods: From July 2014 to October 2017, 28 children (47 feet) with flexible flatfoot with an average age of 11.7±2.1 (range 9-14) years underwent osteotomy combined with soft tissue surgery. The American Orthopaedic Foot and Ankle Society (AOFAS) ankle-hindfoot score and Foot and Ankle Outcome Score (FAOS) were used to evaluate the preoperative and postoperative clinical outcomes. The talo-navicular coverage angle (TNCA) and talar–first metatarsal angle (T1MA) on the foot anteroposterior view, calcaneal pitch angle and Meary’s angle on the foot lateral view, and calcaneus valgus angle (CVA) on the Saltzman view were also observed. Results: All patients were followed up for an average duration of 29.7±8.6 months. Mean AOFAS and FAOS significantly improved from 56.6±8.0 and 47.4±9.5 preoperatively to 88.4±3.9 and 83.2±6.8 at final follow-up (P<0.001). respectively. There were statistically significant differences between preoperative and postoperative scores in all FAOS subscales (P<0.001). Radiographic parameters, such as TNCA (P<0.001) and T1MT (P<0.001) on foot AP views, calcaneal pitch angle (P=0.014) and Meary , s angle (P<0.001) on foot lateral views, and CVA (P<0.001) on Saltzman views, were significantly improved. All patients and their parents were satisfied with the functional outcomes. Conclusion: Osteotomies combined with soft tissue procedures are an effective strategy for flexible flatfoot deformity in children, as it results in favorable radiographic and functional outcomes. obtained excellent outcomes without complaints of lateral discomforts. These results may be due to the utilization of Cotton osteotomy and the strong adaptative ability in children.

The patients with a thigh tourniquet were placed in the supine position on operation table under general anesthesia in addition to the regional nerve block. First, we performed gastrocnemius recession or percutaneous Achilles lengthening according to the preoperative Silfverskiold test. Then, an incision is made below the tip of the fibula along with the peroneal tendon. The sural nerve should be protected. After the subperiosteal dissection, a 45º osteotomy was performed with an oscillating saw. The posterior aspect of the calcaneus was translated medially at approximately 0.5-1.0cm to realign the hindfoot. The K-wire was used to fix the fragment temporarily. We raised the lower limb and evaluated the heel alignment under direct vision. It was exactly determined with an intraoperative Saltzman view. The MDCO was fixed with two 4.0-mm cannulated screws. If the epiphysis was open, a contoured mini-plate or K-wire was used for fixation ( Fig. 1a).
Following the MDCO procedure, midfoot abduction was evaluated clinically. Then, we extended the incision over the calcaneocuboid joint for the LCL procedure. The osteotomy cut was made 1 cm posterior to the calcaneocuboid joint. With the osteotomy distracted, the position of the talus relative to the navicular is checked clinically and radiographically. Once the position is corrected, the allograft with an appropriate size was used to maintain the reduction. Fixation was performed with K-wire, cannulated screw or plate (Fig. 1f).
After completing the hindfoot osteotomy, medial soft tissue reconstruction was performed. A medial incision was made over the posterior tibial tendon (PTT). We debrided and repaired the mild or moderate PTT tear. If the PTT presented a large, extensive and degenerative lesion, repair and flexor digitorum longus (FDL) transfer were adopted. FDL was harvested from the Henry's knot and passed from the plantar to dorsal direction through a drill hole and sutured to itself in mild inversion. The deltoid and spring ligaments were evaluated. Imbrication suturing before FDL transfer was performed with appropriate tension. In children with a painful accessory navicular bone, which was more prevalent among this age group, we always tried to use screw for fixation of the accessory bone, if the bone fragment was large enough. The excision of the entire accessory navicular bone and reattachment with the suture anchor were necessary if the bone was small (Fig. 1b-d).
At the completion of the soft tissue procedures, Cotton osteotomy was performed with residual improved from 56.6±8.0 preoperatively to 88.4±3.9 at final follow-up (P<0.001). A statistically significant difference was shown in the mean FAOS scores, which improved from 47.4±9.5 preoperatively to 83.2±6.8 at final follow-up (P<0.001). There were statistically significant differences between preoperative and postoperative scores in all FAOS subscales (P<0.001). Radiographic Three patients had complications. One patient had sural nerve palsy, but the symptoms disappeared after neurotrophic drug treatment for 6 months. One patient had residual pain in the medial foot, which was relieved by using custom-made insole and gradually disappeared after 3 months. Another patient with diabetes had superficial infection. With careful wound care and oral antibiotic treatment, the incision healed at 1 month postoperatively. Nonunion and delayed union were not present in our cohort. All the patients returned to previous sporting activities without functional limitation and pain. Some authors previously observed that LCL or double calcaneal osteotomy was optimal for severe forefoot abduction deformity and also better realigned the midfoot transverse plane deformities [5,9,17]. A cadaveric study also reported that LCL can restore 60% of hindfoot valgus deformities associated with 100% forefoot abduction deformity [18]. In the current study, there were 16 feet that underwent LCL and 13 feet that underwent double calcaneal osteotomy. They all obtained satisfactory outcomes except for one patient who had sural nerve palsy for 6 months. Thus, it is critical to expose the sural nerve under direct visualization and protect it carefully during operation. The most common complication of LCL was calcaneocuboid subluxation and increased risk of calcaneocuboid arthritis [15], which did not occur in our patients. The patients with an average age of 11.7 years had a strong growth potential to remodel the soft tissue balance. Furthermore, joint degenerative changes did not occur because of the short follow-up time.
Osteotomy and FDL transfer procedures are widely accepted in adults, and they have facilitated flatfoot reconstruction and resulted in excellent outcomes [19]. Accompanied with hindfoot osteotomies, soft tissue procedures maximally maintain the stability of the medial column and restore  Although still controversial, when a patient still has a symptomatic flatfoot with painful accessory navicular bone, overall foot alignment reconstruction should be performed rather than dealing with accessory bone alone. In addition, the large accessory navicular bone was fixed with a screw in this study, which differed from Cha's procedure [24]. We think that the bone-to-bone healing is easier than the tendon-to-bone healing.
The Cotton osteotomy is an excellent adjunct to hindfoot correction procedures. When the residual forefoot supination is present after restoring hindfoot alignment, Cotton osteotomy is indicated. Our study showed that children who underwent osteotomies combined with soft tissue procedures achieved promising clinical and radiographic outcomes. However, this study has several limitations.
Firstly, the patients underwent different combinations of corrective surgeries and had different preoperative conditions. It was difficult to assess objectively the efficacy of each procedure.
Furthermore, the sample size was small, which can result in a statistical bias and preclude the definitive conclusion of the operative procedures. Finally, we did not analyze the outcome until the epiphysis closed. As children grew older, the reconstruction results will perhaps change gradually.
Thus, a prospective randomized controlled study involving a larger number of patients and longer follow-up time is warranted to determine the efficacy of osteotomies combined with soft tissue procedures in children.

Conclusion
The osteotomy method combined with additional soft tissue procedures is an effective treatment for flexible flatfoot in children, as they achieve significant improvement in functional and radiographic outcomes.    showed the talo-navicular coverage angle (TNCA) on the foot AP view.