A Closer Look At Allografts For Lateral Ankle Ligament Reconstruction
Take care to retract the superficial peroneal nerve branches. Use a #15 blade to perform sharp dissection to release both the ATF and CF ligament off the tip of the lateral malleolus. Try to preserve their attachment to the talus and calcaneus to help with proper placement of the graft. At this point, you should have adequate exposure to the lateral aspect of the body-neck junction of the talus, the distal portion of the lateral malleolus and the lateral wall of the calcaneus just inferior and posterior to the critical angle of Gissane.
During dissection, the allograft should be thawing on the back table. Peroneus longus allograft works well. The graft length is between 19 and 22 cm. This will provide enough for two grafts if necessary. Cut the graft into two 10-cm pieces. The reconstruction begins at the tip of the lateral malleolus. Position one end of the graft into the tip of the lateral malleolus and secure it with a bio-tenodesis screw. Start just anterior to the tip of the malleolus and orient the tunnel slightly posterior as you advance the tunnel superiorly.
There are two key points here. First, take care to avoid using too large of a screw and splitting the lateral malleolus. A 6- or 7-mm diameter screw works well. Second, do not aim too horizontal to exit the posterior aspect of the malleolus. The tunnel is primarily a superior direction.
Once the proximal portion of the reconstruction is stable, start on the two distal attachments. At this point, fluoroscan is recommended on the patient’s original ligaments to help identify the proper location for the insertion of the allograft. Split the allograft longitudinally so it has a “Y” shape as it exits the tip of the lateral malleolus. Position the foot in a dorsiflexed and everted position. Create a tunnel under the peroneal tendons and pass the posterior arm of the allograft under the tendons.
With the foot everted, secure the allograft into the calcaneus with a bio-tenodesis screw oriented lateral to medial. This is typically a 5- or 6-mm screw. While maintaining the foot position, insert the anterior arm of the allograft into the talus from lateral to medial. The length of the screw into the calcaneus is 20 to 25 mm and the length of the screw into the talus is 10 to 15 mm.
Avoid making the allograft too long. If the allograft is too long, it will “bunch” up in the osseous tunnel and the surgeon will not be able to tension this properly with the bio-tenodesis screw. As the surgeon tightens the screw, the allograft should be tight. If it is not tensioning as one tightens the screw, remove the screw and trim some of the graft so it is shorter.
Check the reconstruction by lifting the leg off the table. The heel should stay in a neutral position. My personal philosophy with this repair is better too tight than too loose. Perform layered closure with the capsule. Place the leg in a splint with slight eversion and dorsiflexion.
Pertinent Insights On The Post-Op Course
Place the patient in a non-weightbearing compression splint for two weeks. The position of the splint is everted and dorsiflexed. The patient then wears a walking cast for two weeks. Then advance the patient to a walking boot for four weeks. I also recommend a night splint during this period of time. Patients can start range of motion exercises. At eight weeks post-op, the patient can wear a shoe with an ankle brace when walking outside.
Physical therapy can also start at this time. The physical therapist must be aware of the extent of the surgery and not treat this like a typical ankle sprain. Return to sports takes about four months on average. I recommend the use of an ankle brace with return to sports for at least six to nine months.
Dr. Grambart is the foot and ankle surgeon for the Division of Orthopedics at the Carle Clinic Association in Champaign, Ill. He is a Clinical Instructor at the University of Illinois School of Medicine. Dr. Grambart is a Fellow of the American College of Foot and Ankle Surgeons.