Endoscopic Flexor Hallucis Longus Transfer for the Management of Acute Achilles Tendon Ruptures: A Prospective Case Series Report With a Minimum of 18 Months' Follow-Up

Current treatment concepts for Achilles tendon rupture

Achilles tendon rupture is a common and primary cause of lower limb tendon injury suffered during sports-related activities. The causes of Achilles tendon rupture include the calf muscle and tendon overuse, poor tendon quality, and various medical conditions. Historically, acute Achilles tendon rupture was treated conservatively. However, historical techniques are now associated with an increased risk of rerupture. To address this problem, open repair has been proposed. Open repair is associated with a reduced risk of rerupture; however, it is also closely associated with wound complications, like wound infection, whose treatment is time-consuming and costly. Therefore, minimally invasive Achilles tendon repair has been proposed as a promising option with acceptable functional outcomes. Nevertheless, despite its benefits, minimally invasive Achilles tendon repair is associated with increased risks of sural nerve injury and rerupture. In this review, we evaluate the currently used treatment strategies for acute Achilles tendon rupture and their historical evolution to provide evidence-based recommendations for physicians.

Endoscopically Assisted Percutaneous Harvesting of the Flexor Hallucis Tendon in Zone 2: An Anatomical Study

BACKGROUND

Flexor hallucis longus (FHL) transfer is a well-established method for treating chronic Achilles tendon ruptures and tendinopathy. Harvesting of the FHL tendon in zone 2 results in greater length but is also associated with an increased risk of injury to the medial plantar nerve and requires an additional plantar incision. Because of the anatomic proximity of the FHL tendon to the tibial neurovascular bundle in zone 2, the purpose of this study was to investigate the risk of vascular or nerve injury with arthroscopic assisted percutaneous tenotomy in zone 2 of the FHL tendon.

METHODS

Endoscopically assisted percutaneous FHL transfer was performed on 10 right lower extremities from 10 cadaveric human specimens. The FHL tendon lengths and the relationship between FHL tendon and the tibial neurovascular bundle at zone 2 was analyzed.

RESULTS

We observed a complete transection of the medial plantar nerve in 1 case (10%). The mean length of the FHL tendon was 54.7 ± 9.5 mm and the mean distance from the distal stump of the FHL tendon to local neurovascular structures was 1.3 ± 0.7 mm.

CONCLUSION

There is a risk of neurovascular injury after endoscopic FHL tenotomy in zone 2. The tenotomy site is within 2 mm of the local neurovascular structures in the majority of cases. The additional length gained from this technique is unlikely to be required for the majority of FHL tendon transfer procedures. If additional length is needed, we would recommend the use of intraoperative ultrasonography or a mini-open approach to minimize injury risk.

LEVEL OF EVIDENCE

Level V, expert opinion.

Primary augmentation of percutaneous repair with flexor hallucis longus tendon for Achilles tendon ruptures reduces tendon elongation and may improve functional outcome

PURPOSE

Achilles tendon ruptures (ATR) result in loss of strength and function of the gastrosoleus-Achilles tendon complex, probably because of gradual tendon elongation and calf muscle atrophy, even after surgical repair. Flexor hallucis longus (FHL) augmentation not only reinforces the repair and provides new blood supply to the tendon, but also protects the repair, internally splinting the repaired Achilles tendon, maintaining optimal tension. We prospectively compared the clinical outcomes of patients with acute ATR, managed with either percutaneous repair only or percutaneous repair and FHL augmentation.

METHODS

Patients with acute ATR undergoing operative management were divided into two groups. Thirty patients underwent percutaneous repair under local anesthesia, and 32 patients underwent percutaneous repair augmented by FHL tendon, harvested through a 3 cm longitudinal posteromedial incision, and transferred to the calcaneus, under epidural anesthesia. All patients were treated by a single surgeon between 2015 and 2019 and were followed prospectively for 24 months.

RESULTS

The percutaneous only group was younger than the augmented one (35.4 ± 8.0 vs 40.4 ± 6.6 years, p = 0.01). In the augmented group, 25 patients stayed overnight and only 5 were day cases, whereas in the percutaneous only group 4 patients stayed overnight and 28 of them were day cases (p < 0.001). The duration of the procedure was significantly longer in the augmented group (38.9 ± 5.2 vs 13.2 ± 2.2 min, p < 0.001). At 24 months after repair, the Achilles tendon resting angle (ATRA) was better in the augmented group (-0.5 ± 1.7 vs -4.0 ± 2.7, p < 0.001), as was Achilles tendon rupture score (ATRS) (91.7 ± 2.2 vs 89.9 ± 2.4, p = 0.004). Calf circumference of the injured and the non-injured leg did not differ between the groups, as did the time interval to single toe raise and the time interval to walking in tiptoes. Although plantarflexion strength of the operated leg was significantly weaker than the non-operated leg in both groups, the difference in isometric strength of the operated leg between the groups was not significant at 24 months (435 ± 37.9 vs 436 ± 39.7 N, n.s.).

CONCLUSION

Percutaneous repair and FHL tendon augmentation may have a place in the management of acute Achilles tendon ruptures, reducing tendon elongation and improving functional outcome.

LEVEL OF EVIDENCE

Level II.

Early analysis shows that endoscopic flexor hallucis longus transfer has a promising cost-effectiveness profile in the treatment of acute Achilles tendon ruptures

PURPOSE

Current options for treating an Achilles tendon rupture (ATR) include conservative and surgical approaches. Endoscopic flexor hallucis longus (FHL) transfer has been recently proposed to treat acute ruptures, but its cost-effectiveness potential remains to be evaluated. Therefore, the objective of this study was to perform an early cost-effectiveness analysis of endoscopic FHL transfer for acute ATRs, comparing the costs and benefits of current treatments from a societal perspective.

METHODS

A conceptual model was created, with a decision tree, to outline the main health events during the treatment of an acute ATR. The model was parameterized using secondary data. A systematic review of the literature was conducted to gather information on the outcomes of current treatments. Data related to outcomes of endoscopic FHL transfers in acute Achilles ruptures was obtained from a single prospective study. Analysis was limited to the two first years. The incremental cost-effectiveness ratio was the main outcome used to determine the preferred strategy. A willingness-to-pay threshold of $100,000 per quality-adjusted life-year was used. Sensitivity analyses were performed to determine whether changes in input parameters would cause significant deviation from the reference case results. Specifically, a probability sensitivity analysis was conducted using Monte Carlo simulations, and a one-way sensitivity analysis was conducted by sequentially varying each model parameter within a given range.

RESULTS

For the reference case, incremental cost-effectiveness ratios exceeded the willingness-to-pay threshold for all the surgical approaches. Overall, primary treatment was the main cost driver. Conservative treatment showed the highest direct costs related to the treatment of complications. In the probabilistic sensitivity analysis, at a willingness-to-pay threshold of $100,000, open surgery was cost-effective in 50.9%, minimally invasive surgery in 55.8%, and endoscopic FHL transfer in 72% of the iterations. The model was most sensitive to parameters related to treatment utilities, followed by the costs of primary treatments.

CONCLUSION

Surgical treatments have a moderate likelihood of being cost-effective at a willingness-to-pay threshold of $100,000, with endoscopic FHL transfer showing the highest likelihood. Following injury, interventions to improve health-related quality of life may be better suited for improved cost-effectiveness.

LEVEL OF EVIDENCE

Level III.

Outcomes of Percutaneous Achilles Repair Compared With Endoscopic Flexor Hallucis Longus Tendon Transfer to Treat Achilles Tendon Ruptures

BACKGROUND

Both percutaneous and endoscopically assisted methods are reported to produce good results in the surgical management of acute Achilles tendon ruptures. The aim of this retrospective study was to compare between a percutaneous method and a recently described isolated endoscopically assisted flexor hallucis longus (FHL) transfer method as surgical means of management in patients with acute Achilles tendon ruptures.

METHODS

One hundred seventeen patients were included in the current study and divided into 2 groups: 59 patients who underwent percutaneous Achilles repair (PAR Group) and 58 patients who underwent isolated endoscopic FHL transfer (FHL Group) were compared. Patients were clinically evaluated using American Orthopaedic Foot & Ankle Society (AOFAS) ankle-hindfoot score, Achilles tendon Total Rupture Score (ATRS), and Achilles tendon resting angle (ATRA) measures. In addition, ankle plantarflexion power, FHL dynamometry, Tegner activity levels, and return to previous levels of activity were also documented for all patients.

RESULTS

Nine months after surgery, patients in the FHL transfer group were more likely to be able to return to normal activities (91% vs 73%, P < .01). Thirty months after surgical treatment, we found no difference in ATRS, AOFAS, ATRA, ankle plantarflexion strength, or Tegner activity scores between study groups. Overall complications were reported in 6 patients in the FHL group (10.3%) and in 8 patients in the PAR group (13.6%). No major neurovascular or skin complications were encountered.

CONCLUSION

The current study demonstrated satisfactory and comparable results and complications when comparing isolated endoscopic FHL tendon transfer or percutaneous Achilles tendon repairs in the surgical management of acute Achilles tendon ruptures.

LEVEL OF EVIDENCE

Level III, retrospective controlled trial.

Endoscopic Flexor Hallucis Longus Transfer for the Management of Acute Achilles Tendon Ruptures in Professional Soccer Players

BACKGROUND

Acute Achilles tendon ruptures (AATRs) that occur in athletes can be a career-ending injury. The aim of this study was to describe return to play and clinical outcomes of isolated endoscopic flexor hallucis longus (FHL) transfer in active soccer players with AATR.

METHODS

Twenty-seven active male soccer players who underwent endoscopically assisted FHL tendon transfer for acute Achilles tendon ruptures were included in this study. Follow up was 46.2 (±10.9) months after surgery. Return to play criteria and clinical outcome measures were evaluated.

RESULTS

All players returned to playing professional competitive soccer games. Return to active team training was at a mean of 5.8 (±1.1) months postoperatively. However, return to active competitive match play occurred at a mean of 8.3 (±1.4) months. Twenty-two players (82%) were able to return to their preinjury levels and performances and resumed their professional careers at the same soccer club as their preinjury state. One player (3.7%) shifted his career to professional indoor soccer. At 26 months postoperatively, the mean Tegner activity scale score was 9.7 (±0.4), the mean Achilles tendon total rupture score was 99 (±2), and the mean American Orthopaedic Foot & Ankle Society ankle-hindfoot score was 99 (±3). No patients reported any great toe complaints or symptomatic deficits of flexion strength.

CONCLUSION

The current study demonstrated satisfactory and comparable return to play criteria and clinical results with minimal complications when using an advanced endoscopically assisted technique involving FHL tendon transfer to treat acute Achilles tendon ruptures in this specific subset of patient cohort.

LEVEL OF EVIDENCE

Level II, prospective cohort case series study.

Patient reported outcomes and satisfaction following single incision Flexor Hallucis Longus (FHL) augmentation for chronic Achilles tendon pathologies

BACKGROUND

Various procedures exist to augment or reconstruct the Achilles tendon (AT) in patients suffering from chronic pathologies. The aim of this study is to assess patient reported outcomes and satisfaction following single incision FHL augmentation using a short tendon harvest with interference screw fixation.

METHODS

This is a multicentre case series where postoperative patient reported outcome and satisfaction scores were collected on 30 patients. Outcome measures included EQ-5D, EQ-VAS, Achilles Tendon Rupture Scores (ATRS), and satisfaction scores. Scores were also collected on the unaffected limbs for comparison.

RESULTS

Mean patient age was 61 years (range 40-79, SD 11). Mean EQ-5D index value was 0.750 (0.100-1.00, SD 0.238), and mean EQ-VAS score was 74 (36-99, SD 15), at a mean follow-up of 57 months (4-118, SD 32). For patients with ≥24 months' follow-up, a mean deficit of 16 ATRS points was found between the operated and unaffected limb. Overall satisfaction was over 86%. In cases of chronic AT rupture, younger age and increasing time from initial injury to surgery were predictors of greater residual deficit. No serious complications or failures occurred.

CONCLUSIONS

FHL augmentation using short tendon harvest and interference screw fixation is a safe treatment option. It appears to take at least 24 months to functionally recover following this procedure, and despite a residual function deficit, there is a high level of patient satisfaction. Further studies are required to determine optimal patient selection and timing of surgery.