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Employing Free Semitendinosus Allograft For Repair Of A Chronic Achilles Tendon Rupture

Large defects in chronic Achilles tendon ruptures pose a significant challenge to the foot and ankle surgeon. Accordingly, these authors discuss the use of semitendinosus allograft to repair these defects in two cases.

The Achilles tendon is the most commonly injured tendon in the lower extremity due to sports-related injuries.1 This is due to the “watershed area” of the Achilles tendon, approximately two to six cm proximal to the insertion and with a decreased vascular supply due to lack of surrounding muscle and a thin paratenon.2 Therefore, this portion of the Achilles tends to be a common rupture site.3 

Clinicians typically diagnose an Achilles rupture by noting a palpable defect to the area and via a positive Thompson test, demonstrated by a lack of plantarflexion with compression of the posterior calf over the gastrocnemius muscle. If physical findings are not conclusive, imaging studies can assist with the diagnosis. One may utilize magnetic resonance imaging (MRI) or ultrasound to diagnose acute or chronic ruptures.4 

A chronic Achilles tendon rupture is defined as presenting four to six weeks after the original injury.5 According to the American Academy of Orthopaedic Surgeons, if there are at least two physical examination findings indicating an Achilles tendon rupture, advanced imaging is not necessary.4 Although there is still debate regarding surgical versus non-surgical management of acute Achilles ruptures, most surgeons opt for surgical intervention when treating a chronic Achilles rupture.5 

With a defect greater than 3.0 cm, an end-to-end anastomosis is typically not recommended.6 There are many different techniques and graft types used to bridge an Achilles defect over 3.0 cm, including autografts, allografts, and synthetic grafts. This case series demonstrates the use of a free semitendinosus allograft to bridge the defect in a chronic Achilles tendon rupture. 

A Closer Look At The Patient Presentations 

Patient 1. A healthy 28-year-old male with no past medical history “felt a pop” in his left posterior leg while playing volleyball in June of 2014. He initially followed up with his chiropractor, who ordered an MRI. The MRI revealed a full-thickness tear of the Achilles tendon with the center of the tear approximately six cm above its insertion into the calcaneus. There was also retraction of the torn fibers approximately three cm proximally up the leg. However, the patient did not keep follow up appointments with his chiropractor after the MRI. He presented 30 days later to the emergency department due to continued pain and lack of propulsion in gait. He was a construction worker and felt the injury was affecting his work performance. 

A clinical evaluation revealed a palpable dell in the left Achilles tendon and a positive Thompson test. The left posterior ankle exhibited mild edema was at the time with neurovascular status intact. There was pain upon palpation to the posterior leg and heel. Muscle power was 4/5 to the left lower extremity. He was admitted to the hospital from the emergency department for surgical intervention.

Patient 2. A 37-year-old healthy male with no significant past medical history injured his left posterior leg while playing basketball in November 2014. Of note, he suffered a ruptured right Achilles tendon in 2007 and underwent surgical repair. The patient presented to the emergency department the day of injury. A physical examination revealed a palpable dell in the left Achilles tendon and there was a positive Thompson test. One could also appreciate non-pitting edema of the left ankle and intact neurovascular status to both extremities. 

The patient was advised to undergo surgical repair at that time. However, he decided to follow up with his previous surgeon. That surgeon no longer accepted his insurance, which delayed intervention by seven weeks. The patient returned to the emergency department for re-evaluation in January 2015 approximately 44 days after the initial injury. He was subsequently admitted for surgical intervention.

Of note, both patients denied recent fluoroquinolone use.

Key Intraoperative Findings And Step-By-Step Pearls

For each patient, there was prone positioning, application of a thigh tourniquet inflated to 300 mmHg and general anesthesia. The surgeon directed attention to the posterior inferior leg overlying the Achilles tendon and made an incision approximately six cm long and slightly medial to avoid the course of the sural nerve. Reflection of the paratenon revealed fibrotic scar tissue within the Achilles watershed area. This tissue was friable, weak and nonviable. After the removal of all non-viable tissue, a 4.0 cm deficit remained between the proximal and distal ends of the Achilles tendon in both patients. 

After making a stab incision through the proximal and distal stumps of the tendon from medial to lateral, the surgeon pulled a fresh-frozen free semitendinosus allograft through each of the stab incisions, and sutured the graft back onto itself with the patient's foot in a plantarflexed position (See second image above). The surgeon proceeded to tack the graft to the Achilles tendon in all four corners with an absorbable suture (See third image above). After suturing the midportion of the graft onto itself with a nonabsorbable suture, the surgeon then cut the excess semitendinosus tendon (See fourth image above). Using one of the free ends of the excess tendon, the surgeon cut the allograft longitudinally, fanned it out and wrapped it circumferentially to create an allograft jacket around the repair site (See fifth image above). After a layered closure, surgeons applied a short leg cast in plantarflexion. 

What About The Post-Op Results?

Both patients had an uneventful post-operative period. There were no post-operative infections. Both patients were non-weightbearing with crutches for six to eight weeks and partial weightbearing in a CAM boot without crutches for an additional two to four weeks. Once the patients transitioned to full weightbearing, their only restrictions were running, jumping and other high-impact activities for the remainder of the recovery period of up to six months.

Four years after the procedure, patient 1 reported no pain and had full plantarflexion range of motion. The patient denied any complaints related to the surgical site. He participates in all prior activities and returned to work as a construction worker.

Patient 2 was unable to follow up. However, during a phone interview that occurred at two years post-operatively, the patient denied pain and stated he had returned fully to normal activity with no limitations. He relayed no complications since his post-operative course discharge to the present time.  

What The Literature Reveals

Young and colleagues employed a similar approach for chronic Achilles tendon ruptures, but there are some differences in their technique.7 Not only did they use a free gracilis tendon, these authors had a different method of reinforcing the tendon graft to the Achilles tendon. Young and coworkers sutured the gracilis tendon to the Achilles tendon at each entry and exit point with further reinforcement using partially-attached plantaris tendon autograft. In our case studies, we reinforced/the graft by tacking the graft onto itself rather than the Achilles tendon. 

In this case study, we discussed two cases of chronic Achilles rupture repair using free semitendinosus allograft. Due to the chronic nature of the rupture in both cases, the gap of the tendon rupture after debridement was greater than four cm. In the classification developed by Kuwada, a grade III tear constitutes any rupture with a defect measuring three to six cm.6 Surgical repair is recommended via an end-to-end anastomosis with autogenous tendon graft flap or synthetic graft. When there is a grade IV tear with a defect greater than six cm, the surgeon can perform a gastrocnemius recession. 

Since the publication of Kuwada’s recommendations, several surgeons have used various techniques in repairing chronic Achilles ruptures including turndown flaps, tendon transfers, tendon grafts and augmentation with synthetic materials.8 Common tendons surgeons use in transfers to reinforce the repair of chronic Achilles tendon ruptures include the flexor hallucis longus, the flexor digitorum longus and the peroneus brevis.9 However, transfer of the flexor hallucis longus tendon can result in weakening of hallux flexion and even flexion of the ankle.10 The flexor digitorum longus can affect propulsion strength.11,12 Similar to a flexor hallucis longus tendon transfer, a peroneus brevis tendon transfer can affect the ankle by weakening eversion.13,14 Since both patients in our review were young and active, there was concern for weakening of muscle function with a tendon transfer. This led to the decision to use a free semitendinosus allograft instead.

Sarzaeem and coauthors published a study evaluating open Achilles tendon repairs with gaps greater than six cm while using free semitendinosus grafts in a variety of techniques.15,16 The study authors noted good functional results with an improvement in the Achilles Tendon Rupture Score.15,16 In two studies, Maffulli and coauthors recommended the use of the semitendinosus graft in ruptures with a large gap due to its length and strength.17,18 In another report on Achilles tendon repair, Maffulli and colleagues used a free semitendinosus tendon graft as well as an interference screw.9 

Although the use of internal fixation in the repair of chronic Achilles ruptures may be useful and beneficial, there are inherent associated risks. Wound dehiscence is a common complication. Open Achilles tendon repairs have a nine percent incidence of superficial infections.14 In the presence of a superficial infection, there is always the possibility of bacteria seeding to any implanted hardware. 

In Conclusion

Complications are possible with any surgery and risk reduction should be a factor in determining which technique and procedure will best suit your patient. In using a free semitendinosus allograft, we achieved positive long-term outcomes in both cases. This technique eliminates the possibility of muscle strength loss as well as bacterial seeding to implanted hardware. Therefore, we recommend use of a free semitendinosus allograft in the repair of chronic Achilles ruptures with large gaps. 

Although this case study was limited with only two patients, the technique can provide another alternative in treating chronic Achilles ruptures. While this procedure is not a first-line treatment due to cost, it is a reliable and proven technique when the deficit is too large for primary repair.  

Dr. Cheema is a previous Chief of Orthopedic Surgery at Saint Barnabas Medical Center in Livingston, NJ. He retired in 2018.

Dr. Hart is an Associate of the American College of Foot and Ankle Surgeons and is in private practice in Union, NJ.

Dr. Patel is an Associate of the American College of Foot and Ankle Surgeons and is in private practice in Central Florida.

Dr. Sawh is an Associate of the American College of Foot and Ankle Surgeons and is in private practice in Central Florida.

Online Exclusives
By H. Mahmood Cheema, MD, Zachary T. Hart, DPM, Jalpen Patel, DPM and Dayana J. Sawh, DPM
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