Clinical Outcomes in Patients With Minimally Invasive Surgical Approach Combined With Plantar Tendon Transfer Repairing Neglected Achilles Tendon Rupture Compared to the Conventional Approach of V-Y Tendon Plasty: A Retrospective Study With Two Years Follow-Up

Unlike acute Achilles tendon rupture (AATR), neglected Achilles tendon rupture (NATR) requires usually tendon grafting procedures for repair tendon defects caused by removing scar tissue. The conventional open surgery of V-Y tendon plasty and minimally invasive technique with plantar tendon transfer had been described, but the long-term ecacy between the two techniques still needs further certication. Methods


Introduction
Achilles tendon (AT) is the largest and strongest tendon as well as the most frequently ruptured tendon in the human body 1 . Acute Achilles tendon rupture (AATR) was commonly caused by vigorous sports such as football, basketball, and tennis, which often developed a neglected Achilles tendon rupture (NATR) with misdiagnosis for more than 4 weeks 2 . A greater tendency of postoperative complications and functional damages could take place in patients with NATR than in acute Achilles tendon rupture 3 . Hence, there is a consent that NATR should be treated with operation unless patients with contraindications of surgery 4 . And Wong J et al. also demonstrated that the increasing rate of AT re-rupture and decreased functional results are related to nonoperative treatment closely 5 .
NATR, which causes the gap formed between the proximal and distal stumps and is lled with numerous scar tissues,might be acquired by the AATR with non-operative treatment for four weeks 6,7 . This scar tissue is too fragile than the normal tendon to meet a good functional recovery. It's suggested to be excised in operation clearly, though the end-to-end repair is di cult to perform. The conventional surgery of V-Y tendon plasty has been reported by some works of literature to repair NATR with a favorable clinical e cacy 8,9 . However, a 10-15cm longitudinal, slightly curved central skin incision would be created to operate the surgery, which will lead to severe trauma and a long postoperative scar on the skin of the posterior leg undoubtedly. On the other hand, various types of minimally invasive surgical approaches have been reported by many researchers for the treatment of NATR with good functional recovery and fewer complications 10,11 Table 1). The operation time and blood loss in surgery and the complications of re-rupture, soft tissue infection, tendon exposure, tendon elongation, and adhesion in postoperative management were collected for analysis. Patients in two groups were taught standard physical exercise therapy and postoperative rehabilitation without immobilization, whose curative effect has been illustrated in our previous research 14 . The evaluation of ATRS, AOFAS were performed at months 3, 6, 12, and 24, and the dorsi exion, the calf circumference, and the heel raise test were evaluated at follow-up month 24.

Surgical Procedure
All surgical procedures were performed by the same surgeon, with the support of the same team. The epidural analgesia and stabilized with a tourniquet in the prone position were applied in all patients. All patients were classi ed into two groups according to different surgical procedures. 25 patients underwent a conventional surgical approach of V-Y tendon plasty in group A. Of these patients, a 15cm longitudinal, slightly curved central skin incision was created from the middle third of the gastrocnemius muscle, and it was also suggested to curve towards the distal end medially to reduce the risk of injury to the sural nerve 15 . The surgical procedure has been relatively mature, and the details were showed as follows (Fig. 1).
The 21 patients, treated with a novel minimally invasive surgical approach that we have reported in previous research, were contained in Group B 16 . Achilles tendon were exposed by two separate longitudinal incisions, which resembled a scythe or letter "J" (Fig. 2) 17 . If necessary, two 3-4 cm connective incisions around the Kager's triangle and extended to the tendon rupture site were permitted. Careful dissection and complete release of tissue adhesions around the Achilles tendon, and the osteophytes with calcaneal tubercle hyperplasia were removed and the scar tissue between the distal and proximal ends of the Achilles tendon was removed too. The ankle joint was in an extreme plantar exion position, and the mean gap between the distal and proximal end of the Achilles tendon rupture was 4.05 ± 1.32 cm (range, 2-6 cm) in group B. In the extreme plantar exion of the ankle joint, PDS-II can be used as the traction line twice, respectively, through the distal incision of the Achilles tendon, and continuous traction for more than ten minutes. From the distal incision, 3-6 longitudinal holes, approximate 2.0cm deep, were drilled in the calcaneus within the calcaneal insertion using a 2.5mm (in diameter) Kirschner wire to ensure the regenerated tendon attached to the bone rmly. After that, a transverse percutaneous calcaneal bone tunnel was drilled with a 3.0mm (in diameter) Kirschner wire to prepare for percutaneous "Yurt bone" suturing 14,17,18 . The plantar tendon was considered to be the most ideal biological suture graft material for strengthening the repair of the Achilles tendon. And the plantar tendon was used to bridge the ends of the distal and proximal Achilles tendon stump which play a dual role in tendon transplantation and bridging suture.

Postoperative Management
According to our previous research, similar postoperative management in all patients was recommended 14 . All patients in two groups were advised to lie prone or lateral on the bed without xation or orthosis and with the knee at 60° exion and the ankle joint at 45° plantar exion. In addition, patients were instructed for an early active motion of the ankle and knee joints by a detailed physical rehabilitation regimen from postoperative day 1. In this program, the increasing intensity of motion exercises was initiated at postoperative day 10, followed by another increase at week 3. Full weightbearing exercise, standing on the toes, and squatting were initiated at postoperative week 4. It should be noted that the exercise of tiptoe stepping on the operated side of the tendon on the balance 3 ~ 9 kg from postoperative day 3 was a novel component of the present program, which was greatly useful not only for reducing the patient's fear of early motion of the ankle joint but also for the surgeon to determine the time of walking with weight-bearing exercises according to the increase in tiptoe stepping. respectively, and the defects in two groups after the debridement of the scar tissue of the Achilles tendon were 7.04 ± 1.90 cm (range, 4-11 cm) and 4.05 ± 1.32 cm (range, 2-6 cm), respectively (Table 1).
There were signi cant advantages of group B than A in operation time and blood loss (P < 0.001). Of 25 patients in group A, the soft-tissue infection was exposed to three patients which included two surface infections and one deep infection. And a tendon exposure just exposed to group A. On the other hand, only one tendon re-rupture was found in group B. Of all patients, there was no occurrence of tendon elongation or adhesion by ultrasonography, MSCT in two groups ( Table 2).  (Table 3). Two groups both have good recovery of calf circumference, dorsi exion, and heel raise test at follow-up months 24 (Fig. 3). However, there were much better in group B than group A by the heel raise test (Fig. 4) (Table 4).

Discussion
NATR has been an important challenge to surgeons for a long time, due to the high rate of misdiagnosis of AATR more than four weeks 2 . A large amount of scar tissue lled in the gap between the proximal and distal ends of the ruptured Achilles tendon, which will take a negative impact on the normal reconstruction of the tendon. Thus, an operation removing this scar tissue for a better functional recovery was required undoubtedly. However, the conventional operation repairing the Achilles tenon always need to perform a large skin incision. Therefore, a minimally invasive surgical approach that can complete the clear tissue is the direction that surgeons have been exploring.
Various operative techniques have been reported to repair NATR with a good outcome 8,9,[19][20][21][22] [24][25][26][27][28] . However, the clinical outcome of patients with NATR who underwent a minimally invasive surgical approach still needs to evaluate furtherly. In the present study, we compared the 25 patients who underwent the conventional open operation (V-Y tendon plasty) with the 21 patients who were treated by the two separate minimally invasive surgical approaches that have been reported in our previous research to provide an experience for the operative selection to treat in NATR.
In this study, the minimally invasive surgical technique involved two joint incisions in the shape of a longitudinal ipped scythe or letter "J" is currently our technique of choice for repairing AT partial injury in NART patients, as we feel the additional biological properties of the minimal incision are important for the higher activity demands 14,17,29 . In this study, the two incisions were disconnected and shortened to approximately 3.5cm respectively 16 . Along the gap between the surface projections of Kager's triangle and the posterior tibial artery to the border of Kager's triangle, the curves were extended by the distal sections; the proximal sections stopped at 12-14cm approximately above the AT insertion on the posterior calcaneus. The liner sections' length of the incisions was almost 3-4cm. The veins which supply blood to the wound to promote healing were protected by this particular incision shape effectively. In addition, the separation of the proximal ends of the ruptured tendons from the surrounding tissues to pull out the tendon for tension-free suturing should be avoided to minimize the impact on the local blood circulation.
Apart from the above advantages, there was a modest impact on the local blood circulation, rapid recovery of sports function, and fewer complications are reported in the minimally invasive surgical approach too. In the eye of anatomy, the blood circulation of AT depends on the posterior tibial and peroneal arteries through the tendon sheath arteries. Besides, the sheath arteries were nourished by the proximal peroneal artery, which connects with the posterior tibial artery to supply sheath arteries to the heel together, in the middle of the surface projection of Kager's triangle (at the same horizontal level of the ankle joint). Since that, there are tra c veins between the saphenous and the small saphenous. Unfortunately, these veins are in the great possibility of damaged unavoidably when V-Y tendon plasty was performed, which will put a negative impact on tendon healing further. In our observation, compared with the conventional approach of the V-Y tendon plasty technique, the minimally invasive technique provides a better situation for patient's postoperative exercise with less blood loss and short operation time ( Table 2).
Complications related to the avascular nature of the posterior midline or "S" incision, are common, including high skin tension after suturing and wrinkled heavily, increasing the chance of necrosis of skin as well as soft tissue infection, which may cause tendon exposure eventually. In group A, there were three cases of soft tissue infection, two cases of super cial infections, and one case of deep infection, and there was one case of tendon exposure. In group B, there was one case of Achilles tendon re-rupture (  26 . Therefore, it is inevitable that the conventional open surgery will damage the soft tissue in the ankle and the course of tendon restoring, but there is an obvious advantage engaged in this surgical plan to repair a large tendon defect after resection of scar tissue (Table 1).
In a word, the minimally invasive surgical approach takes advantage of subcutaneous adipose tissue between the malleolus and AT and beneath Kager's triangle to promote incision closure and wound healing 14,17,18,32 . The scythe-shaped incision chosen by the above surgery alleviates the pressure of the wound during early functional exercise, which can prevent tendon exposure and minimizes damage to the scar by shoes effectively. In this present study, the clinical outcome in two groups was evaluated by ARTS, AOFAS, dorsi exion, calf circumference, and Heel raise test with least two years follow-up (Tables 3  and 4). Compared with group A, patients with the minimally invasive surgical approach experienced a desirable functional recovery at months 3, 6, and 12. However, the difference between the two groups was shrunk over time gradually and there was no difference between the two groups at year two (Table 3).
Moreover, patients in group B had a better outcome in heel raise test compared with patients in group A at follow-up year two, which may relate to earlier functional exercise (Table 4). Patients with a minimally invasive technique more like to accept an early high-intensity ankle exercise, which will better for the early functional recovery and the heel raise. Therefore, for patients with large Achilles tendon defects, we still recommend the use of the conventional operation to repair, but for patients with the defect (≤ 6cm), we deem that the minimally invasive surgical approach with less trauma, fewer complications, and high aesthetics should be advised.

Conclusion
In the present study, patients who underwent the minimally invasive surgical approach showed superiority in decreasing blood loss and accelerating wound healing, which prevented tendon infection and exposure. Compared with the conventionally traumatic technique, the minimally invasive surgical approach allowed earlier functional rehabilitation therapy, which promoted reconstruction of the Achilles tendon 14,17,29 . And it is an optimal choice to treat patients with less tendon defect (≤ 6cm) after removing scar tissue. All methods in this retrospective study were carried out in accordance with the Declaration of Helsinki. This study was approved by the Ethics Committee of The First Aliated Hospital of Xinjiang Medical University. Written informed consent was obtained from all patients for their data to be recorded in our study.

Consent for publication
Informed consent was obtained from all patients for their data to be published in our study.
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