October 16, 2019
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Midsubstance repair is an alternative technique to treat Achilles tendon ruptures

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The minimally invasive midsubstance surgical technique for acute midsubstance Achilles tendon ruptures passes sutures longitudinally through the distal Achilles stump and anchors proximal sutures into the calcaneus for early range of motion and weight-bearing.

The midsubstance SpeedBridge (Arthrex) technique may be particularly helpful for distal Achilles tears when a limited amount of the patient’s tendon is available.

Distal anchor preparation

If fixation of the proximal Achilles tendon sutures to bone is desired, the midsubstance construct can be used instead of distal Achilles tendon percutaneous suture passing. Two longitudinal incisions are made along the posterior aspect of the heel at the peripheral insertion of the Achilles tendon distal to the maximal convexity. Incisions are spaced along the sides of the Achilles tendon insertion. A 3.5-mm drill and drill guide are used through each incision and placed flush against bone (Figure 1). The drill is inserted into bone and oriented slightly convergent towards midline and slightly plantar. Each drill hole widened using a tap.

Figure 1. If direct fixation of the proximal Achilles tendon to bone is desired, the midsubstance construct can be used instead of percutaneous suture passing through the distal Achilles tendon. Longitudinal incisions 2-mm long are made along the distal aspect of the Achilles tendon insertion. A 3.5-mm drill and drill guide are used through each incision, oriented slightly convergent toward midline and slightly plantar (a). Each drill hole is widened using a 4.75-mm tap (b). A suture passer is used through the center of the distal Achilles tendon stump and through the proximal incision to retrieve one side of the proximal sutures (c). Suture passing is repeated for the other pair of sutures (d).
Figure 2. Sutures are cycled 10 times to remove residual creep in the sutures proximally (a). The ankle is plantar flexed to tension the Achilles tendon and held in place by an assistant. Each pair of sutures are passed through the eyelet of a 4.75-mm SwiveLock anchor (Arthrex) and each anchor is gently malleted into the corresponding calcaneal drill hole followed by hand tightening until the anchor is flush with bone (b). Paratenon, subcutaneous tissue and skin closure is performed followed by placement of a splint vs. tall CAM boot (c).

Source: Andrew R. Hsu, MD

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A rigid suture passer with inner Nitinol wire is passed longitudinally through the center of the distal Achilles tendon stump using controlled, continuous pressure. The surgeon’s dominant thumb guides the sharp tip of the passer through tendon. The passer is brought out through the proximal incision to retrieve one pair of proximal sutures. During suture passing, the Nitinol wire is drawn back to the tip of the passer. Then, the entire device is removed from the distal incision. Trying to pass the sutures only through the inner Nitinol wire can result in suture tangling and increased resistance.

The above steps are then repeated for the sutures on the opposite side. Suture pairs are placed under maximal tension and cycled 10 times to remove any residual suture creep (Figure 2).

Achilles tensioning, anchor insertion

The ankle is plantar flexed to tension the Achilles so that end-to-end proximal and distal tendon apposition is achieved. An assistant holds tension on the opposite pair of sutures to ensure that Achilles tension does not change prior to anchor insertion. The rupture site should be palpated to confirm that no residual gap or excessive overlap of the tendon ends is present. Sutures are passed through the eyelet of the 4.75-mm anchor, which is gently malleted into the calcaneal drill hole and hand tightened until the anchor is flush with or slightly buried in the bone.

The position of the drill holes can be rechecked with a short, blunt K-wire prior to anchor insertion because their relative position will change as the ankle is plantar-flexed. Before removing the anchor insertion handle, the tip of a mosquito clamp can be used to “feel” the bony surface and confirm if the anchor is flush or buried.

With the ankle still held in plantar flexion, the above steps are repeated and the other anchor is inserted. Sutures are cut flush with the anchor followed by carrying out wound irrigation and layered closure of the paratenon and subcutaneous tissues.

Stages of rehabilitation

After either percutaneous or midsubstance surgery, a soft dressing is placed over the incision(s). Patients are typically made non-weight-bearing in an equinus posterior mold splint or tall controlled ankle motion (CAM) boot with heel lifts. Some surgeons may allow immediate range of motion and partial weight-bearing depending on their preference. Early range of motion with weight-bearing is encouraged more for the midsubstance construct since the proximal tendon is secured directly to bone and has less risk of early elongation or suture pullout from the tendon.

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If the incision is healed at 2 weeks, sutures are removed and patients are made partial weight-bearing in a tall CAM boot with gentle active range of motion exercises. If there is concern about wound healing, sutures are maintained for an additional 1 week to 2 weeks with local wound care, as needed.

After 3 to 6 weeks, progressive weight-bearing begins with peel-away heel lifts. These are about 2-cm thick, in three layers, each of which is removed as pain allows every 3 to 4 days. The goal is being full weight-bearing with the foot flat at 5 to 6 weeks after surgery.

Physical therapy that focuses on ankle motion and Achilles stretching and strengthening is started at 5 to 6 weeks depending on the patient. From 6 to 10 weeks after surgery, patients are transitioned into normal shoe wear with increasing activities. No dorsiflexion past neutral is allowed for 10 to 12 weeks after surgery as over-lengthening of the tendon can occur with excessive dorsiflexion and lead to decreased push-off strength. Impact activities are allowed based on pain and swelling starting at 12 weeks. Full return to baseline athletic activities and sports may not occur until a full 5 to 6 months after surgery.

Disclosures: Anderson reports he is a paid consultant for Amniox, Artelon, Arthrex, Bioventus, DJO, NuVasive, Wright Medical Technology and Zimmer Biomet. Berlet reports he is a paid consultant for Artelon, DJO, Wright Medical Technology and Zimmer Biomet. Hsu reports he is a paid consultant for Arthrex.

This is part 2 of a two-part Surgical Technique article. In part 1, the authors discussed the percutaneous Achilles repair technique.