Abstract
Background
Chronic Achilles tendon (AT) ruptures pose a significant reconstructive challenge. While various surgical techniques have been described, comparative data between open allograft augmentation and endoscopic autograft transfer remain scarce.
Methods
This study evaluated 41 patients with chronic AT rupture treated surgically: 21 underwent open repair with tendon allograft (Group A) and 20 received endoscopic transfer of the flexor hallucis longus (FHL) tendon (Group B). Complications were recorded, and clinical outcomes were compared between groups.
Results
At a minimum 24-month follow-up, both groups showed excellent functional and clinical outcomes. Complication rates were low and comparable: two in Group A (wound dehiscence, deep vein thrombosis) and three in Group B (tibial nerve irritation, plantar pain, insufficient tensioning of the tendon transfer).
Conclusions
Both techniques achieved high patient-reported outcomes and low complication rates. Open repair with allograft provides durable reconstruction in complex cases, while endoscopic FHL transfer offers a less invasive alternative.
Level of evidence
Level III, retrospective comparative study.
1
Introduction
Acute achilles tendon (AT) rupture is a common injury, with a reported incidence of 31–55 per 100,000 per year in Scandinavian countries . A chronic AT tear usually results from a neglected or misdiagnosed acute rupture. Although the exact incidence of chronic AT ruptures is unknown, up to 20–25 % of acute AT tear are missed and lead to chronic AT ruptures . There is no consensus in defining a chronic lesion; however, a systematic review by Flint et al. suggests that the term chronic should be used to define a rupture presenting at least four weeks after the initial injury .
It is known that early diagnosis and surgical treatment of acute AT tear provides good clinical and functional outcome with a low failure rate . When acute AT ruptures are untreated, the lesion will spontaneously heal with a scar tissue bridge between the two stumps . Nevertheless, the poor quality of the new tissue will lead to tendon elongation and the potential risk for rerupture , . Furthermore, the force arm of the gastrocsoleus complex is lengthened, leading to weakened heel-rise strength. Additionally, the gastrocsoleus complex becomes atrophic due the retracted proximal stump, exacerbating the plantarflexion strength loss on the affected side. The reduced plantarflexion strength affects activities of daily living, sport activities .
Delayed diagnosis and reconstruction of AT tears after six weeks is a technically challenging and demanding surgery with inconsistent outcomes . Many different surgical methods have been reported for the reconstruction of chronic AT ruptures: V-Y myotendinous lengthening, turndown flaps, tendon transfers (peroneus brevis, flexor digitorum longus, gracilis, and flexor hallucis longus [FHL]), and allografts/synthetic grafts, have been reported ,,,, . Recently, different studies reported good results of endoscopic assisted minimally invasive reconstruction for chronic AT ruptures using the FHL tendon ,, . However, no compartive studies have directly compared endoscopic FHL transfer with more traditional tenchniques. This study aimed to compare the clinical results of endoscopic FHL transfer with open allograft augmentation in patients with chronic AT tears.
2
Material and methods
This was a retrospective comparative study including patients treated across three centers for chronic AT tear. All adult patients with chronic AT tear (> 6 weeks) were considered for inclusion. The AATR was diagnosed by a physical examination with evaluation of the soft tissues, palpation of the Achilles tendon, evaluation of plantar flexion against resistance and the Thompson test. When available, rupture of the tendon was confirmed using ultrasound or MR imaging. Only patients with AT tear in the middle third of the tendon were included. The exclusion criteria were: (i) patients who were < 18 years of age at the time of surgery; (ii) follow up < 24 months; (iii) patients. The study was conducted according to the Declaration of Helsinki concerning medical research and written informed consent was obtained from all the patients. To evaluate the postoperative status of patients, the Achilles tendon Total Rupture Score (ATRS) , the American Orthopedic of Foot and Ankle Society (AOFAS) ankle−hindfoot score , and visual analogue scale (VAS) were used for evaluation of the clinical efficacy of the surgery during the final clinical follow-up visit, conducted at a minimum of 24 months after surgery.
2.1
Surgical procedures
Open surgery was performed in one center while two centers performed endoscopic procedures treatment. Both surgeries were performed with the patient prone, under regional anaesthesia and a tourniquet was placed on the thigh. The foot was positioned at the edge of the operating table.
In the open group, a 10-cm to 15-cm longitudinal median skin incision was made. The paratenon, if not disrupted, was incised longitudinally in the midline for the length of the skin incision. Scar tissue in both the proximal and distal stumps was excised to reach viable tendon. A shortening Z-plasty was performed to restore the correct length of the tendon, which was verified intraoperatively by comparing the resting tension of the healthy side . The tendon suture was subsequently reinforced using a tendon allograft, which was inserted through the distal and proximal stumps and sutured. The patient maintained immobilization in a plaster cast without weightbearing for 6 weeks, with suture removal approximately 14 days after surgery. After cast removal, gradual weight bearing was permitted for the next 4 weeks, combined with active and passive ankle mobilization to recover dorsiflexion. At 12 weeks post-surgery, full weight-bearing was allowed, and the initiation of muscle strengthening activities commenced.
In the endoscopic group, two portals were used: medial and lateral para-achilleal. Blunt dissection of the soft tissues was performed to reduce the risk of injury to the sural nerve. A 4.0-mm arthroscope was then placed through the lateral portal, and the correct point for the medial portal is identified using the light of the arthroscope as a guide, just anterior to the Achilles tendon. The posterior chamber of the ankle was cleaned, taking care not to exceed the limit of the FHL in order to avoid damaging the medial neurovascular structures. An endoscopic calcaneoplasty was performed in patients where deemed necessary (9 cases out of 20 treated with this technique) using a 4.0 mm bone burr to remove the posterosuperior edge of the calcaneus, an important step to allow for the placement of the transfer as close as possible to the Achilles insertion. The Rouviere and Canela fascia were then incised proximally to visualize the muscle belly of the FHL, facilitating greater mobilization and trajectory towards the posterior portion of the calcaneus. The ankle and hallux were fully plantar flexed, and a clamp was introduced through the posteromedial portal to grasp the FHL tendon and retract it proximally to achieve maximum tendon length (preferably not less than 20 mm), sectioning it with arthroscopic scissors introduced through the same portal. The harvested tendon was withdrawn outside the posteromedial portal, and a Krackow suture was performed on the free distal stump of the tendon. A looped K-wire was then inserted through the posteromedial portal, identifying the point for creating the half tunnel for the transfer, directed from the dorsomedial to the plantar lateral aspect under direct arthroscopic visualization. The calcaneal tunnel was produced using a powered drill, with length and diameter corresponding to those of the harvested FHL. The free stump of the FHL tendon, through the previously performed suture threaded into the loop of the K-wire, was introduced into the calcaneal half tunnel. While maintaining tension on the suture and keeping the ankle in plantar flexion to mimic the resting tension of the healthy side, the FHL was secured with an interference screw. The transferred tendon was then visualized and palpated through both the posteromedial and posterolateral portals to ensure proper fixation. The portals were subsequently sutured, and a dressing and compressive bandage were applied. The ankle was immobilized in plaster cast in plantar flexion for 14 days, during which the patient was allowed to ambulate without weight-bearing. After suture removal at two weeks, the foot was positioned at 90 ° in walker boot and patients could gradually increase weight-bearing for an additional 15 days. Approximately 30 days post-surgery, the boot could be removed, allowing for full weight-bearing ambulation and the initiation of specific rehabilitation.
2.2
Statistical analysis
All analyses were performed using SPSS Version 23.0 (SPSS Statistics V20; SPSS, Inc, an IBM Company, Chicago, IL). An unpaired t -test was conducted for comparison of the normally distributed variables; the Mann–Whitney U test was used for variables with non-normal distributions. Differences in proportions for categorical variables was assessed with the use of chi-squared tests. The P value was set at a significance level of 0.05.
3
Results
A total of 21 patients underwent Achilles tendon reconstruction and augmentation with allograft (group A), and 20 patients underwent FHL endoscopic transfer (group B).
Group A consisted of 19 males (90.5 %) and 2 females (9.5 %), while group B included 18 males (90 %) and 2 females (10 %). The average age was 55 ± 14.4 years for group A (range 24–82) and 54.2 ± 15.2 years for group B (range 27–77).
In group A, 18 patients had chronic lesions, 3 had re-ruptures of previously acute injuries treated conservatively. In group B, 16 patients had chronic lesions, and 4 had re-ruptures.
The interval between injury and surgery in group A was 23.3 ± 22.0 weeks (range 7–101), while for group B it was 16.8 ± 9.2 weeks (range 7–41). The mean follow-up was 62.3 ± 28.2 months (range 16–109) for group A and 38.05 ± 21.0 months (range 24–84) for group B.
The demographic characteristics were comparable between both groups (p > 0.05), except for the follow-up (p < 0.05).
The mean ATRS score in group A was 92.1 ± 8.9 (range 59–100), while in group B it was 93.0 ± 9.8 (range 62–100). The mean AOFAS score was 97.3 ± 6.2 (range 74–100) for group A and 94.3 ± 9.3 (range 60–100) for group B.
Residual pain, assessed using the VAS score, was 0.3 ± 1.3 (range 0–6) in group A and 0.6 ± 1.1 (range 0–4) in group B.
Two cases of complications were noted in group A: one patient experienced wound dehiscence, necessitating a procedure for skin coverage with a dermo-epidermal graft and remained in a cast for an additional 4 weeks, this led to a mild delay in rehabilitation, but did not significantly impact final outcome scores (both ATRS and AOFAS scores were 100); another patient developed deep vein thrombosis (DVT) despite receiving prophylaxis with low molecular weight heparin, which was treated with medical therapy.
In group B, three complications occurred: one patient developed progressive joint stiffness and tibial nerve compression symptoms, requiring a second surgery for open posteromedial nerve decompression and arthrolysis, during which scar entrapment suggestive of perineural fibrosis was identified; the complication likely resulted from fibrotic adhesion rather than intraoperative error, and a more conservative dissection near the tarsal tunnel may help prevent similar cases in the future; another patient experienced plantar pain at the surgical site, necessitating a local release procedure approximately 2 months after surgery, which was likely related to soft-tissue irritation caused by the graft passage through the calcaneal tunnel and may be prevented by optimizing tunnel positioning with minimal graft prominence; in the third case, the final tension of the transfer was deemed insufficient, but the patient was able to perform daily activities without limitations, so no surgical revision of the tendon transfer was undertaken.
No re-ruptures were reported in either group. Table 1 summarizes the data regarding the analyzed outcomes.
Table 1
Clinical Outcomes of the study groups; sd: standard deviation.
| Group A | Group B | P value | |
|---|---|---|---|
| ATRS score (mean±sd) | 92.1 ± 8.9 | 93.0 ± 9.8 | P > 0.05 |
| AOFAS score (mean±sd) | 97.3 ± 6.2 | 94.3 ± 9.3 | P > 0.05 |
| VAS score (mean±sd) | 0.3 ± 1.3 | 0.6 ± 1.1 | P > 0.05 |
| Complications (n.) | 2 (9.5 %) | 3 (15 %) | P > 0.05 |
| Re-intervention (n.) | 1 | 2 |
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