Opportunistic Biological Augmentation during Acute Achilles Tendon Repair: A Novel Surgical Concept With Three-Year Follow-Up—A Case Report

Clinical presentation

A 43-year-old male presented 2 days after sustaining a right Achilles tendon injury during recreational football. He reported sudden posterior ankle pain with inability to plantarflex or push off. He had no significant past medical history.

Clinical findings

• Positive Thompson test ^[7]
• Palpable gap over the Achilles tendon
• Loss of active plantarflexion strength.

Imaging

Ultrasound confirmed a complete Achilles tendon rupture with loss of continuity and a hypoechoic defect at the rupture site. At 3-year follow-up, ultrasound demonstrated restored tendon continuity with no evidence of re-rupture (Fig. 1a and b).

Operative findings and technique

Open repair was performed 6 days post-injury under general anesthesia with the patient in the prone position. A posterior longitudinal incision (~11 cm) was used with careful protection of the sural nerve.

Intraoperative findings

The rupture margins demonstrated (Fig. 2a, b, c, d):

• Severely frayed and macerated tendon ends
• Poorly defined margins consistent with “mop-end” appearance
• High-risk tissue quality for standard repair.

Primary repair

The Krackow locking-loop technique was performed using non-absorbable polypropylene sutures. Tendon approximation was achieved with appropriate tension balanced against the contralateral side. A circumferential running polypropylene suture was added to reinforce the repair construct and reduce gap formation (Fig. 2e and f).

Biological augmentation

A substantial viable local soft tissue was identified interposed between the repaired tendon and the posterior tibial surface. Its macroscopic appearance – including mixed pink-red coloration with white fibrous streaking, punctate bleeding on gentle manipulation, supple musculotendinous consistency, and anatomical location – was presumed to represent traumatically avulsed tissue arising from the distal gastrosoleus musculotendinous complex (yellow arrows, Fig. 2c and d). Histological confirmation was not obtained, as biopsy was not clinically indicated; the intraoperative decision was based on macroscopic assessment of viability, and histological analysis would not have altered the surgical plan regardless of the tissue type identified. Rather than discarding it, the tissue was preserved and sutured directly over the repaired tendon, where it served as a biological onlay augmentation layer (yellow arrows, Fig. 2e and g). The wound was closed in layers (Fig. 2g) and the ankle immobilized in plantar flexion using a below-knee cast.

Post-operative management

Post-operative management followed a conservative, staged protocol as documented in the medical record:

• Weeks 0–5: Below-knee cast in plantar flexion
• Weeks 5–7: Posterior slab in neutral (plantigrade) position
• Week 7: Removal of immobilization – wound healed and tendon strength clinically accepted; the patient was encouraged to begin gentle self-directed ankle mobilization
• Week 8 (~2 months): Formal supervised physiotherapy initiated; partial weight-bearing (PWB) commenced; range-of-motion (ROM) exercises continued
• Week 11: PWB with single crutch; ROM exercises continued
• Week 13 (~3 months): Full weight-bearing (FWB) achieved; occasional ankle swelling noted, managed with limb elevation and continuation of ROM exercises.

Following the 13-week clinic visit, the patient did not attend further scheduled appointments. All subsequent rehabilitation milestones were reported by the patient at the 3-year follow-up assessment and are based on patient recall.

Return-to-sport timeline (Table 1)

Outcome at 3 years

At final follow-up, the patient demonstrated (Fig. 3):

• Full return to competitive football
• No pain or functional limitation
• Full symmetric ankle range of motion
• Successful single-leg heel-rise
• No significant calf atrophy
• Negative Thompson test.

Although numerical goniometric values were not formally recorded, clinical examination and supplementary photographic documentation (Fig. 3d and e) confirmed symmetrical full ankle motion comparable to the contralateral side. Video documentation of the post-operative full range of motion is available as supplementary material, comprising three video clips: Bilateral heel-rise (Video 1),

single-leg heel-rise on the operated side (Video 2), and ankle range of motion on the operated side (Video 3). The Achilles Tendon Total Rupture Score (ATRS) was 100/100, with maximal scores across all domains including pain, stiffness, muscle strength, and daily activities ^[8].

Surgical considerations

The Krackow technique provides strong tendon fixation and is widely accepted in Achilles tendon repair. Biomechanical studies demonstrate high failure loads, especially when combined with augmentation techniques ^[9]. Alternative techniques such as the Giftbox or triple Kessler methods offer comparable strength profiles, but the Krackow technique remains preferred by many surgeons due to its familiarity and reproducibility ^[10].

In cases with severely compromised tissue quality, primary repair alone may be insufficient, and additional mechanical reinforcement is often required. Circumferential suture reinforcement offers additional mechanical stability and may reduce early gap formation, particularly in poor-quality tendon tissue ^[5]. This approach is simple, cost-effective, and applicable in any surgical setting.

Opportunistic biological augmentation

This case proposes the concept of “opportunistic biological augmentation” – where viable local soft tissue is preserved and utilized rather than excised. The rationale for preservation was based on four considerations:

1. Viability: Confirmed by punctate bleeding on gentle manipulation, contrasting sharply with the avascular macerated tendon ends.
2. Biological contribution: Vascularized tissue may contribute to a favorable biological environment that supports tendon healing through mechanisms including cellular activity, neovascularization, collagen deposition, and tissue remodeling.
3. Mechanical support: The augmentation layer may provide an additional protective covering over the repair construct, potentially helping to shield it during the early healing phase.
4. No donor-site morbidity: Tissue already present within the operative field is utilized ^[4].

The central concept of this report is not the introduction of a new repair technique, but rather a change in intraoperative decision-making: The recognition and preservation of viable local soft tissue that would otherwise be discarded.

This concept aligns with previous descriptions of local tissue augmentation in Achilles reconstruction ^[11,12], but extends its application to the acute setting using tissue that would conventionally be discarded. Hallock described the “Achilles wraparound flap,” using local soleus muscle to enhance healing ^[11], and Maffulli and Ajis advocated local muscle flaps in chronic ruptures ^[12]. This report extends these biological principles to the acute setting.

To the best of our knowledge, no previous publication has formally described the preservation of traumatically displaced viable local tissue as an opportunistic biological augmentation strategy during acute Achilles tendon repair. We therefore propose this as a novel surgical concept warranting further study.

Importantly, the augmentation in this case was not pre-planned. It resulted from an intraoperative judgment when unexpectedly viable local tissue, which would otherwise have been discarded, was encountered during routine exploration of the rupture site. This opportunistic decision represents the essence of the proposed concept: not a new suture technique or a new tissue flap, but a new way of thinking – transforming tissue that would conventionally be discarded into a potentially valuable biological resource without additional planning, dissection, or morbidity.

Unlike conventional augmentation techniques – which require pre-operative planning, tendon harvest, additional dissection, or formal reconstruction procedures – opportunistic biological augmentation is an intraoperative decision based solely on the preservation of traumatically displaced but viable local tissue that would otherwise have been discarded. (Table 2)

This approach requires no additional equipment beyond the standard Achilles tendon repair set, no additional tissue harvest, and no donor-site morbidity. This maneuver did not require appreciable additional operative time or special equipment, as tissue preservation was incorporated into the standard repair steps without a separate operative stage.

Regarding the precise identity of the augmentation tissue: Its macroscopic characteristics – including a mixed pink-red coloration with white fibrous streaking, punctate bleeding on gentle manipulation, supple musculotendinous consistency, and anatomical location between the repaired tendon and the posterior tibial surface – were collectively consistent with traumatically avulsed viable tissue from the distal gastrosoleus musculotendinous complex – though this could not be confirmed histologically. Importantly, the mixed coloration and texture observed intraoperatively (Fig. 2e and f) preclude definitive identification as purely muscular tissue; the white fibrous component suggests a tendinous or fascial contribution alongside the muscular element. Formal histological confirmation was not performed, as biopsy was not clinically indicated in this acute setting. The tissue is therefore described in descriptive anatomical terms rather than as a definitively identified structure. Regardless of its precise histological identity, its macroscopic viability made it a valuable biological augmentation substrate, and its utilization is justified on functional and biological grounds rather than histological certainty.

Functional outcome

The patient achieved a 100/100 ATRS and full return to competitive sport at 3 years, with outcomes appearing comparable to published return-to-sport data following Achilles tendon repair ^[13,14]. Surgical management is also associated with lower re-rupture rates compared with non-operative treatment ^[3,15]. A recent systematic review and meta-analysis reported that 65–100% of patients returned to sport between 3 and 13.4 months post-surgery ^[13,14], while among professional athletes the mean time to return to competitive play is approximately 11 months with a return rate of 76% ^[16]. A scoping review of elite athletes confirmed return rates exceeding 70% following surgical repair ^[17], and a review of return-to-sport outcomes further supports surgery in active patients with high functional demands ^[18]. The 12-month milestone to first competitive match in this case falls within the published range, and the extended timeline to full pre-injury fitness at 16 months is consistent with a cautious approach appropriate for cases with severely compromised tissue quality.

The post-operative rehabilitation milestones documented up to 13 weeks fall within the accepted range for complex Achilles tendon repairs, reflecting an appropriately cautious approach given the poor intraoperative tissue quality. While more accelerated early mobilization protocols have been described ^[19], the graduated progression to FWB at 13 weeks is consistent with published protocols for cases with compromised tendon integrity.

It is important to acknowledge that the favorable outcome reported in this case cannot be attributed solely to the biological augmentation. The meticulous primary repair, circumferential suture reinforcement, and structured early rehabilitation each contributed to the overall result. The present report does not seek to establish causality between the augmentation and the outcome. Rather, it demonstrates the technical feasibility of preserving viable local soft tissue and introduces this maneuver as a potentially valuable biological adjunct that warrants prospective investigation.

Limitations

This is a single case report, limiting generalisability. Histological confirmation of the augmented tissue was not performed, as discussed in Section 3.2; the decision was based on macroscopic assessment of viability, and histological analysis would not have altered the surgical plan. Furthermore, the exact time interval between identification of the viable tissue and its incorporation into the repair was not formally recorded, as the decision to preserve and utilize the tissue was made immediately upon encounter during the operative procedure, without a defined waiting period. Post-operative follow-up was documented in the medical record up to 13 weeks. Beyond this point, the patient did not attend scheduled clinic appointments, and all subsequent milestones – including return to jogging, team training, and competitive match play – were based entirely on patient recall at the 3-year follow-up visit. This represents a limitation in the objectivity of the return-to-sport timeline. Furthermore, the rehabilitation protocol was not formally standardised. Despite these limitations, the robust 3-year functional outcomes – including objective measures such as single-leg heel-rise testing, bilateral calf circumference measurement, and a 100/100 ATRS score – provide meaningful evidence supporting the feasibility and potential value of this approach. Furthermore, because this is a single case report, it is not possible to determine the relative contribution of the circumferential suture reinforcement versus the biological augmentation to the excellent clinical outcome. Because only a single patient is presented, reproducibility of this approach across different rupture patterns and tissue presentations cannot be established. Future prospective comparative studies are required to determine whether opportunistic biological augmentation provides measurable benefits beyond meticulous primary repair alone. Advanced post-operative imaging such as magnetic resonance imaging or ultrasound elastography may also help clarify the structural contribution of preserved augmentation tissue in future studies.

Conflict of Interest:

Nil

Source of Support:

Nil

Consent:

The authors confirm that informed consent was obtained from the patient for publication of this article