Central third fascia slide technique may restore function in Achilles tendon defects
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Patients who sustain an Achilles tendon rupture that is left untreated or fails conservative measures can go onto have substantial impairment in gait and push-off strength, leading to decreased function.
During preoperative planning the surgeon must be ready to debride the poor-quality degenerative tissue that has filled the gap. The gap size dictates the reconstruction options with little to no evidence-based outcomes to support the selected option. For gaps less than 2 cm, an end-to-end repair or step cut is recommend; for gaps between 2 cm to 4 cm, a V-Y fascial advancement is recommended; and for gaps 4 cm to 6 cm, a central third turn down has been recommend. Another variable to consider is the addition of a flexor hallucis longus (FHL) tendon transfer. The FHL has been shown to hypertrophy over time, adding additional strength with minimal functional loss to the great toe. Gaps larger than 6 cm cause a unique surgical dilemma with no clear consensus on surgical reconstruction technique.
Source: Kevin D. Martin, DO, FAAOS, FAANA
The present article describes a technique for chronic Achilles tendon defects of larger than 6 cm. The central third fascia slide technique with FHL transfer provides adequate excursion and strength while avoiding use of an allograft.
The central third fascia slide technique is a reconstructive technique that is utilized to treat large, chronically gapped Achilles tendon tears, usually larger than 5 cm to 6 cm. The technique described here is a variation of the V-Y tendinoplasty and fascia turndown method in which the gastrocnemius complex fascia is slid down rather than being “turned down.” This reconstructive technique, like its predecessor, restores gastrocsoleus complex function in damaged or absent Achilles tendons.
Description
The central third fascia slide technique utilizes a posterior midline incision, maintaining full-thickness flaps. A complete debridement of the degenerative Achilles tendon is performed, and the gap is measured. If the gap is greater than 5 cm to 6 cm, the central third fascia slide should strongly be considered, as it eliminates the need for an allograft and serves as a local autograft.
Next, the deep compartment fascia is split and the FHL tendon is identified and cautiously separated from the surrounding tissue, protecting the medial neurovascular bundle. The FHL is then pulled proximally with the ankle and great toe plantarflexed allowing for maximum excursion. An FHL tenotomy is then performed at the level of the subtalar joint, at the junction of zone 1 and zone 2 of the FHL tendon. This location should allow for adequate tendon preparation and transfer. The end of the tendon is tubularized with nonabsorbable suture and measured.
Next, the insertion site is prepared. If the injury is a chronic avulsion, then all the soft tissue to the Achilles insertional footprint is removed and a small saw or rasp is used to contour the calcaneus and establish a bleeding bone bed for tendonous healing. If the gap is proximal, the Achilles footprint is kept intake and incorporated into the repair. A Beath pin is placed approximately 1 cm anterior to the Achilles footprint, dorsal central to plantar distal and out the bottom of the foot. An appropriately sized reamer is then utilized to prepare the tunnel, and the shuttling suture is passed out the plantar aspect of the foot.
The gastrocnemius fascia is evaluated, and any fatty or subcutaneous tissue is removed. The length of the graft needed to fill the Achilles gap is marked, and a bone-tendon-bone style double-blade scalpel (10 mm) is used to sharply release the central 10 mm of the gastrocnemius fascia. The undersurface of the fascia is stripped of any muscular attachments, and the fascia is slid onto the Achilles footprint (previous prepped as above). Two 2.6-mm all-suture FiberTak soft anchors (Arthrex) are placed 1.5 cm from the end of the graft, one medial and one lateral. The two knotless mechanisms are passed through the fascial graft, linked and tensioned down to bone, creating a rip-stop and approximating the fascia down to bone. The collagen-coated suture tape from each anchor is then passed through the fascia just proximal to the rip-stop, crossed and brought distally in a speed-bridge configuration and secured with a 3.9-mm BioComposite SwivelLock Anchor (Arthrex), one medial and one lateral. This configuration maximizes biomechanics and allows the excess nonabsorbable suture to be ran up each side of the graft in a locking configuration.
With the ankle in maximum plantarflexion (20° to 30°), the FHL is pulled into the tunnel and secured with a biotenodesis screw. Maintaining tension at proximal graft and distal gastrocnemius fascia, the graft is secured and the central donor site is closed with the nonabsorbable suture. The repair is tensioned in 20° to 30° on plantarflexion. A meticulous layered closer is performed trying to restore the paratenon and minimize tension across the skin. A well-padded short-leg splint is applied in 20° of plantarflexion.
Postoperative rehabilitation
- non-weight-bearing splint in 15° to 20° of plantarflexion (0 to 2 weeks);
- hands-free crutch to maintain cyclic muscle contractions;
- weight-bear as tolerated in a walking boot with a 1.5-cm heel lift, crutches as needed (2 to 4 weeks);
- initiate blood flow restriction therapy if available;
- transition to a 1-cm heel lift and may discontinue the use of crutches if pain allows (4 to 6 weeks);
- weight-bearing as tolerated in boot with no lifts (6 to 8 weeks); and
- wean from boot into semi-rigid supportive shoes with small heel lift (8 to 12 weeks).
The patient should be able to resume activities of daily living by 3 to 4 months, with a gradual return to all low-impact (no jumping, no running) physical activities by 4 to 6 months. This postoperative protocol has produced favorable results but should be tailored to individual patient needs.
Important tips
- Debride the Achilles until viable tendon is reached, then measure the defect.
- Tension the FHL 15° to 20°, and the fascia slide in maximum plantarflexion.
- Perform a meticulous layered closure, preserving the paratenon as much as possible.
- Incomplete closure of the fascia harvest site may predispose to seroma or hematoma formation.
- Splint for the first 10 to 14 days, allowing for soft tissue and wound healing. Customize the rehabilitation per the individual patient’s needs and abilities while under the guidance of a physical therapist.
Advantages: The Achilles turndown flap technique can lead to the formation of scar tissue at the focal point of the turndown, a region also known as the hinge point, and thus can perpetuate scarring of the repair site. The technique also avoids allograft and associated costs.
Disadvantages: The technique uses a large incision with potential wound healing issues in patients who often have compromised healing potential.
On the horizon: Newer techniques utilizing an endoscopic FHL transfer without reconstruction of the Achilles are showing early encouraging results. The endoscopic transfer mitigates the potential risk of the large incision while benefiting from the added strength of the FHL. My current practice is to discuss each option with the patient and weigh the risk and benefits of each.
- For more information:
- Kevin D. Martin, DO, FAAOS, FAANA, can be reached at The Ohio State University Wexner Medical Center. Martin’s email: kevin.martin@osumc.edu.
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