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

Study Design and Patient Population

This retrospective study included patients treated for acute Achilles tendon rupture at our institution between August 2020 and September 2025. During this period, 45 consecutive patients underwent surgical repair using a dual-incision technique with a Krackow locking suture and over-the-top knot placement. All procedures were performed by experienced orthopaedic surgeons at our institution following a standardized operative protocol.

Inclusion and Exclusion Criteria

The inclusion criteria were as follows: (1) acute Achilles tendon rupture diagnosed by clinical examination; (2) surgical repair performed within 3 weeks of injury; (3) postoperative follow-up of at least 6 months; and (4) follow-up continued until functional recovery plateaued, defined as no further improvement in activity level.

The exclusion criteria were (1) chronic Achilles tendon rupture; (2) rerupture or revision surgery; (3) open or infected injuries; and (4) loss to follow-up before 6 months postoperatively or before functional recovery plateau.

Seven patients were lost to follow-up before 6 months postoperatively, leaving 38 patients for inclusion in the final analysis. Among these, 35 patients had individually reached at least 12 months of follow-up and were included in the functional outcome analyses.

Surgical Technique

All procedures were performed under general anesthesia with the patient in the prone position. Two longitudinal skin incisions (approximately 3 cm each) were made proximal and distal to the rupture site, positioned 2 to 3 cm from the rupture margins. The paratenon over the rupture site was preserved.

For the distal tendon stump, a Krackow locking stitch was placed using Takumi LIGAFIT tape (Aimedic MMT Co, Ltd; width, 1.2 mm). The suture was initiated in intact tendon distal to the rupture, with 3 locking loops placed laterally and 3 medially. The sutures were passed subcutaneously beneath the preserved paratenon using a suture retriever and delivered to the proximal incision.

For the proximal tendon stump, a Kessler stitch was placed using Surgilon (No. 2; Covidien LLC). The suture ends were passed distally through the same subcutaneous tunnel, and traction was applied to approximate the tendon stumps without exposing the rupture site.

A reversed Krackow locking stitch was then applied to the proximal tendon, beginning adjacent to the rupture site and advancing proximally toward the myotendinous junction, with 3 locking loops placed on both the lateral and medial sides. Lateral and medial sutures were matched to maintain anatomical alignment.

With the ankle in maximal plantar flexion, symmetrical tension was applied to restore tendon continuity. The knots were tied on the proximal tendon away from the rupture interface, completing the over-the-top configuration. Final tension was adjusted to achieve approximately 10° greater plantar flexion compared with the contralateral side. The plantarflexion angle was assessed intraoperatively by the operating surgeon through clinical comparison with the contralateral side. The paratenon was preserved, and the subcutaneous tissue and skin were closed with nylon sutures. Postoperatively, a soft dressing consisting of sterile gauze, cast padding, and an elastic bandage was applied without rigid immobilization.

The surgical steps of the dual-incision Achilles tendon repair using Krackow sutures with over-the-top knot placement are illustrated in Figure 1.

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Figure 1.

Surgical technique for dual-incision Achilles tendon repair using Krackow sutures with over-the-top knot placement. (A) A Krackow locking stitch is applied to the distal tendon stump through the distal incision. (B) The distal Krackow sutures are passed proximally through a subcutaneous tunnel created along the medial aspect of the Achilles tendon to minimize the risk of injury to the sural nerve. A Kessler stitch is placed in the proximal tendon stump through the proximal incision, and the suture is passed distally through the subcutaneous pathway. (C) The proximal tendon stump is approximated by traction on the Kessler suture, and a Krackow locking stitch is applied to the proximal tendon. (D) Intraoperative view after completion of the tendon repair. (E) Schematic illustration demonstrating the configuration of the Achilles tendon repair and suture pathway.

Postoperative Rehabilitation Protocol

Postoperative immobilization was not used. Controlled ankle range-of-motion exercises were initiated immediately after surgery.

Partial weightbearing with a step-to gait pattern was initiated once ankle dorsiflexion reached neutral (0°). Progression to a step-through gait was permitted at 3 weeks postoperatively.

Double-leg heel-raise exercises were initiated at 2 months postoperatively, followed by single-leg heel-raise exercises at 3 months. Jogging was permitted once patients were able to perform single-leg heel raises without difficulty. Return to sports activities was allowed at approximately 4 months postoperatively.

Follow-up and Outcome Evaluation

Functional recovery was assessed using the Tegner Activity Scale (TAS), a validated activity level scale ranging from 0 (sick leave or disability) to 10 (participation in competitive sports at an elite level), commonly used to assess functional outcomes in patients with knee and lower extremity injuries. The preinjury TAS was obtained by patient interview at the initial visit. Postoperative TAS was evaluated during routine outpatient follow-up and/or telephone interviews to determine recovery of activity level.

Patients were followed until their postoperative TAS reached a plateau, defined as no further improvement in activity level.

In addition to TAS, functional recovery was further evaluated by recording the time required to achieve a step-to gait pattern and the time to independent ambulation without assistive devices during the postoperative rehabilitation period.

Statistical Analysis

Continuous variables are presented as means and standard deviations, whereas ordinal variables are presented as medians and ranges. Exact 95% confidence intervals for rerupture and complication rates were calculated using the Clopper-Pearson method. All analyses were descriptive and exploratory in nature. Statistical analyses were performed using jamovi version 2.6 (The jamovi project, Sydney, Australia).

Principal Findings

This retrospective consecutive case series evaluated clinical outcomes after Achilles tendon repair using a Krackow locking stitch combined with proximal knot relocation (over-the-top configuration) through a dual-incision approach. The principal finding of this study was that this construct allowed early functional rehabilitation without routine postoperative immobilization while maintaining structural stability, as no reruptures were observed during follow-up. In addition, most patients returned to their preinjury activity level, and complications were limited to superficial surgical site infections.

Early Functional Rehabilitation

Traditional postoperative management after Achilles tendon repair commonly involved cast immobilization in plantarflexion for several weeks to protect the repair site. However, increasing evidence supports early functional rehabilitation. A systematic review and meta-analysis by McCormack and Bovard demonstrated that early mobilization after surgical repair was associated with rerupture rates comparable to cast immobilization while improving patient-reported outcomes and facilitating earlier return to activity. ⁸

Similarly, meta-analyses comparing operative and nonoperative treatment have shown that structured functional rehabilitation reduces differences in rerupture rates between treatment strategies.^2,3 Experimental studies further suggest that controlled mechanical loading enhances collagen alignment, increases tensile strength, and reduces adhesion formation during tendon healing, providing biological support for early mobilization protocols.^9,10

However, most published early rehabilitation protocols still incorporate functional bracing or controlled ankle motion orthoses during the early postoperative phase.^2,3,8 In contrast, the present rehabilitation protocol did not include routine postoperative immobilization. Although the retrospective design and absence of a control group limit definitive conclusions, the absence of rerupture in this series suggests that when sufficient initial fixation strength is achieved, external immobilization may not be mandatory in selected patients. The mean hospital stay in the present study was relatively longer than that typically reported in Western countries, where Achilles tendon repair is frequently performed as an outpatient procedure. In our institution, patients were hospitalized during the early postoperative period to allow supervised rehabilitation and close clinical monitoring. This inpatient setting may have facilitated early mobilization and contributed to the favorable outcomes observed in this series. However, it may also limit the generalizability of our findings to outpatient settings.

Mechanical Considerations of Proximal Knot Relocation

The mechanical integrity of tendon repair depends on suture configuration and knot behavior. The Krackow locking stitch has demonstrated favorable biomechanical properties and strong tendon purchase compared with other core suture techniques in cadaveric testing. ¹² However, suture knots can function as stress concentrators, and failure frequently occurs adjacent to the knot.

The proximal knot relocation technique described by Turker et al ¹¹ positions the knot away from the rupture interface. Relocating the knot proximally may reduce stress concentration at the tendon ends and promote more uniform load distribution across the repair construct. This mechanical configuration may help maintain repair stability even during early functional rehabilitation without postoperative immobilization.

In the present study, a 4-strand Krackow configuration using Takumi LIGAFIT tape provides an estimated ultimate tensile strength of approximately 3708 N, which exceeds peak Achilles tendon forces reported during walking (2.0-2.6 kN). ¹³ Although in vivo loading conditions are dynamic and influenced by neuromuscular control, this mechanical margin may contribute to the structural stability observed despite early mobilization. Recent studies have reported increasing use of suture anchor fixation techniques for Achilles tendon repair, particularly in minimally invasive and insertional approaches. These techniques may provide secure fixation and facilitate early mobilization. However, some reports have also indicated a potential increase in complication rates associated with anchor-based fixation compared with traditional suture techniques. Therefore, although anchor-based methods represent an important contemporary trend, their relative advantages and limitations remain under investigation. ¹⁴

Biological Considerations

Biological preservation is also critical for tendon healing. The paratenon contributes to vascular supply and facilitates tendon gliding. Experimental studies have demonstrated that paratenon disruption may impair tendon healing and alter the remodeling process.

By using a dual-incision approach and avoiding direct exposure of the rupture site, the present technique preserves the paratenon envelope. Maintenance of this biological environment may help preserve vascularity and reduce peritendinous adhesions, potentially contributing to the low rate of wound complications observed in this series. ¹⁵

Early Loading and Functional Recovery

Mechanical loading during gait progression influences the stress experienced by the Achilles tendon. Step-to gait reduces plantarflexion torque during terminal stance, whereas step-through gait increases tensile loading. Previous biomechanical analyses have estimated peak Achilles tendon forces during walking and running to reach approximately 2.7-3.5 times body weight. ¹³ In addition, biomechanical analyses of the gait cycle have demonstrated that Achilles tendon loading increases as the contralateral limb advances and crosses the stance limb during late stance, reflecting the release of stored elastic strain energy. ¹³ To minimize excessive tensile loading during the early postoperative period, step-to gait was therefore initially adopted in our rehabilitation protocol.

The Achilles tendon also functions as a major elastic energy-storage structure, storing and releasing elastic strain energy during locomotion. ¹³ Restoration of tendon continuity with a mechanically stable repair may facilitate earlier recovery of this energy-storage function and support functional rehabilitation.

Comparative clinical studies of early weightbearing protocols have reported rerupture rates of approximately 2% to 5%.^2,3,8 Although direct comparisons are limited by differences in study design, the absence of rerupture in the present cohort suggests that the combination of strong suture fixation, proximal knot relocation, and preservation of the paratenon may provide sufficient mechanical stability to support early rehabilitation.

Limitations

This study has several limitations. First, the study design was retrospective and lacked a control group treated with conventional postoperative immobilization. Second, the sample size was relatively small. Third, long-term tendon elongation and structural remodeling were not systematically evaluated using imaging modalities such as ultrasonography or magnetic resonance imaging. Fourth, biomechanical strength was inferred from previously published experimental data rather than measured directly in vivo. Fifth, the relatively long hospital stay and supervised rehabilitation protocol may limit the external validity of the findings, particularly in health care systems where Achilles tendon repair is commonly managed on an outpatient basis. Prospective comparative studies are needed to confirm the safety and reproducibility of this technique.