Semitendinosus Allograft Augmentation of Lateral Ankle Ligament Reconstruction

45 Semitendinosus Allograft Augmentation of Lateral Ankle Ligament Reconstruction


Steven M. Raikin


Abstract


Failure of rehabilitation for chronic lateral ankle ligament instability often requires surgical reconstruction. Direct anatomic surgical techniques (Broström–Gould) have been described with good long-term outcomes. There are certain situations where direct repair cannot be achieved or where the patient`s available tissue quality or underlying deformity would lead to high failure rates. In these situations, local repair can be augmented with near anatomic reconstruction utilizing allograft semitendinosus tendon. This avoids risking injury to the previously described utilization of the patient’s peroneus brevis tendon (Chrisman–Snook type procedures), which will weaken the dynamic stabilizers of the lateral ankle. An additional advantage is utilizing biologic tissue to enhance local tissue deficiency, positioned isometrically to optimize function and stability.


Keywords: ankle instability, semitendinosus, allograft, augmentation, cavovarus, ligament laxity


45.1 Indications


• Recurrent deformity from failed modified Broström type anatomic reconstruction.


• Recurrent deformity from nonanatomic split peroneus brevis reconstruction.


• Poor local tissue quality due to generalized ligamentous instability (Ehlers–Danlos syndrome).


• Severe varus ankle deformity (varus talar tilt >30 degrees based on weight-bearing radiographs) with complete loss of locally usable tissue.


• Severe hindfoot varus deformity with concomitant lateral ankle ligament instability.


• Associated high-grade tears of their peroneus brevis tendons requiring reconstruction with concern that the dynamic stabilizer of the ankle would be suboptimal and augmentation utilizing an allograft would be beneficial.


45.1.1 Pathology


• Lateral ankle ligament instability.


• Recurrent sprains of the ankle.


• Associated pathology (described earlier) precluding direct anatomic repair.


45.1.2 Clinical Evaluation


History

• Recurrent ankle sprains.


• History of failed physical therapy.


• History/family history of generalized ligamentous instability:


image Ehlers–Danlos syndrome.


image Marfan’s syndrome.


image Recurrent joint instability (shoulder, patella, etc.).


• History of prior surgical reconstruction.


Examination

• Lateral ankle ligament instability:


image Positive anterior drawer test.


image Positive varus stress test.


• Scars from previous surgical repairs may be present.


• Peroneus brevis dysfunction/pain/weakness despite adequate therapy.


• Evaluate for associated cavovarus deformity.


• Evaluate for generalized ligamentous instability:


image Beighton score > 6/9.


45.1.3 Radiographic Evaluation


• Weight-bearing ankle and foot radiographs should be obtained:


image May be normal in many cases.


image Evaluate for cavovarus deformity (hindfoot or forefoot driven).


image Varus talar tilt >30 degrees (without additional varus stressing of the ankle).


• Magnetic resonance imaging (MRI):


image Assess for associated pathology:


image Peroneal tendon pathology.


image Osteochondral lesions talus.


image Ankle/hindfoot arthritis.


45.1.4 Nonoperative Options


• Physical therapy with focus on peroneal strengthening and proprioception training.


• Brace immobilization:


image Semi-rigid ASO (Ankle Stabilizing Orthosis) brace usually insufficient for these severe instability cases.


image Rigid ankle–foot orthosis (AFO; Arizona brace or molded ankle–foot orthosis [MAFO] brace) usually required.


• Activity modification.


45.1.5 Contraindications


• Immune compromise (high risk for allograft transplantation).


• History of or active perioperative site infection.


• Inadequate bone stock for required bone tunnels (usually fibular).


• Severe ankle arthritis requiring arthrodesis (in patient who is not a candidate for ankle arthroplasty that can be performed concomitantly with this procedure).


45.2 Goals of Surgical Procedure


• Lasting stability of the lateral ankle ligamentous complex.


• Maintenance of ankle function and range of motion.


• Prevention of recurrent ankle instability.


45.3 Advantages of Surgical Procedure


• Fresh frozen allograft can be utilized.


• This is freely available in most institutions.


• No immune typing or cross-matching is required.


• No donor site morbidity.


• Allows anatomic positioning of bone tunnels for ligament reconstruction.


45.4 Key Principles


• Anatomic positioning of bone tunnels:


image Anterior talofibular ligament (ATFL) footprint in talus.


image ATFL insertion into fibular.


image Common flexor tendon (CFT) insertion into fibular.


image CFT attachment into calcaneus.


• Adequate length on semitendinosus allograft.


• Interference fixation into bone tunnels.


• Fixation in ankle eversion with maximal tightness of allograft.


• Procedure can be performed in isolation, or combined with anatomic ligament repair.


45.5 Preoperative Preparation and Patient Positioning


• Lateral or sloppy lateral position with a wedge or beanbag under the ipsilateral hip.


• Calf or thigh tourniquet can be used.


• Concomitant procedures are carried out as needed.


45.6 Operative Technique


• The exposure for the reconstruction is dependent on associated procedures.


image If this is the primary procedure, as with cases of Ehlers–Danlos syndrome where the local tissue quality is known to be deficient, a more percutaneous approach can be used. Four small incisions are utilized, one over the ATFL insertion footprint into the talus, a second at the ATFL insertion into the anterior distal fibular, one posterior to the distal fibula, and a final incision over the lateral calcaneus at the calcaneofibular ligament (CFL) insertion (Fig. 45.1a).


image If peroneal or lateral ankle joint exposure is required, the procedure is performed through a curvilinear incision along the path of the peroneal tendons, posterior to the fibula. The flap is elevated in order to gain access to ATFL and CFL (Fig. 45.1b).


45.6.1 Graft Preparation


• Different tendon allograft can be used. The semitendinosus tendon is optimal due to the length of the tendon, which should be at least 20 cm long.


• The allograft is thawed and soaked in antibiotic solution prior to use.


• On the back table, a whipstitch is run through each end of the tendon, tubularizing the tendon (Fig. 45.2).


• A “Chinese finger trap” wrapping suture can be placed around the tendon end with absorbable suture to bullet-tip the end of the tendon and prevent fraying and jamming of the tendon during passage through the bone tunnels.


• Suture ends are left long to pull and tension the tendon through the bone tunnels.


• We usually manually pre-tension the tendon prior to implantation, but the necessity for this remains controversial.


• The thickness of each end of the tendon is measured utilizing a known diameter measuring system (Fig. 45.3).



Jul 19, 2019 | Posted by in SPORT MEDICINE | Comments Off on Semitendinosus Allograft Augmentation of Lateral Ankle Ligament Reconstruction
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