Letter Regarding “Dual-Incision Achilles Tendon Repair Using Krackow Sutures With Over-the-Top Knot Placement for Early Rehabilitation Without Immobilization: A Retrospective Case Series”

Dear Editor,

We have read with great interest the recent article by Yasuda et al ¹ on the dual-incision Achilles tendon repair technique. The authors present a valuable and innovative concept, and their results are promising. We commend them for exploring a rehabilitation protocol that seeks to eliminate routine postoperative immobilization, which, if proven safe and effective, could represent a significant advance in patient care.

We have been actively investigating similar concepts related to repair biomechanics of the Achilles tendon and early functional rehabilitation following its repair, including the biomechanical advantages of different suture configurations ² and the biological role of the paratenon.^3,4

Our findings are aligned with the hypothesis that minimizing stress concentration at the repair site and preserving local biology are key to successful outcomes.^5,6

However, after carefully reviewing the article, we would like to offer a few constructive observations, primarily concerning the generalizability of the conclusions and the interpretation of the data, which may be of interest to your readership.

Generalizability of the Rehabilitation Protocol and Hospital Stay

The authors successfully demonstrate excellent outcomes in a setting with a mean postoperative hospital stay of 7.7 ± 5.6 days. As they acknowledge, this is significantly longer than the standard in many health care systems, where Achilles tendon repairs are often performed as outpatient procedures or with an overnight stay. The close clinical monitoring and supervised rehabilitation possible within this prolonged inpatient period are not easily replicable in an outpatient setting. Although this does not invalidate the findings by Yasuda et al, it is important to explicitly state that the safety of the protocol, particularly the “no immobilization” component, may be highly dependent on this level of supervised care. The conclusions would be strengthened by a clearer distinction between the surgical technique’s inherent stability and the favourable environment provided by the inpatient protocol.

Absence of Objective Biomechanical and Imaging Data

The authors’ discussion relies on previously published experimental data to estimate the tensile strength of their construct. However, without direct, objective measurements of the repair’s healing, such as serial ultrasonography or magnetic resonance imaging (MRI) to assess tendon elongation, gap formation, or structural remodelling, the assertion of ‘mechanical stability’ remains somewhat indirect. Our own work suggests that subtle tendon elongation can occur even in the absence of overt re-rupture, which may affect long-term function but is not captured by the Tegner score alone.^7,8 Including such objective measures in future prospective studies would provide a more robust foundation for the conclusions.

Clinical Significance of the ‘Lack of Immobilization’

Although the absence of re-rupture is excellent, it is worth noting that the Tegner Activity Scale (TAS) scores did not show a significant improvement, with the median score actually decreasing from 7 to 6. This suggests that, although patients reported to have returned to their pre-injury activity level, they may not have fully returned to their pre-injury function or intensity. In our studies on early mobilization, ⁹ we have found that although early mobilization improves recovery time, it does not necessarily guarantee a superior final outcome compared with more traditional protocols. It would be valuable for the authors to discuss whether the considerable effort and resources required for this intensive, non-immobilized protocol led to a clinically superior outcome compared with a standard rehabilitation protocol that includes a short period of protected weight-bearing. ¹⁰

In summary, we believe this is a well-conducted and promising case series that introduces a novel and compelling surgical technique. However, a more cautious interpretation of the results is warranted. The favourable outcomes appear to be the product of a specific and intensive perioperative environment. It would be premature to conclude that the “no immobilization” aspect is the primary driver of the success, or that the surgical repair technique alone enables this. We look forward to reading the authors’ future work, particularly prospective, randomized studies that could definitively validate these findings in a broader, outpatient setting.

Thank you for considering our perspective

Filippo Spiezia, MD, PhD
Department of Health Sciences, University of Basilicata, Potenza, Italy
Department of Orthopaedics and Trauma Surgery, San Carlo Hospital, Basilicata, Italy
Email: spieziafilippo@gmail.com

Francesco Oliva, MD, PhD
Università degli Studi di Roma San Raffaele Telematica, Rome, Italy

Filippo Migliorini, MD, PhD
Department of Orthopaedic and Trauma Surgery, Academic Hospital of Bolzano, 39100, Bolzano, Italy.Department of Life Sciences, Health, and Health Professions, Link Campus University, 00165, Rome, Italy

Nicola Maffulli MD, MS, PhD, FRCP, FRCS(Orth)
Department of Trauma and Orthopaedic Surgery, University La Sapienza, Rome, Italy
Centre for Sports and Exercise Medicine, Barts and the London School of Medicine and Dentistry, Mile End Hospital, Queen Mary University of London, London, England