Reviewing The Medial Malleolar Osteotomy For Enhanced Access To Large Osteochondral Lesions

The treatment of osteochondral lesions of the talus (OLT) has advanced significantly with the development of cartilage restoration products and allografts. Our arthroscopy skills and volume continue to progress, and we are able to reach and treat lesions successfully through minimally invasive approaches. 

More advanced arthroscopy skills along with the known morbidity of medial malleolar osteotomies have narrowed the indications for this procedure. Since the need for this procedure has significantly decreased, we may not be as familiar with performing these osteotomies as we have in the past. Accordingly, I have tried to outline some tips in performing this osteotomy for both the novice and the advanced surgeon.

One indication for performing a medial malleolar osteotomy is gaining access to large posteromedial talar dome lesions. For a medial approach, one should perform this centrally along the medial malleolus posterior to the great saphenous vein and nerve. One can make an anterior arthrotomy in order to identify the joint line and utilize a Hohmann retractor to protect and retract the saphenous nerve and vein. The surgeon should take care to protect soft tissue posterior to the medial malleolus as well. Identify and retract the posterior tibial tendon, and place a Hohmann retractor anterior to the tendon. The posterior tibial tendon is difficult to mobilize and may require opening the sheath to allow fragment mobilization. 

The most common medial malleolar osteotomies are transverse and chevron-shaped osteotomies. I prefer the chevron osteotomy for several reasons: ease of use, stability and greater visualization. Prior to either osteotomy, I recommend inserting the appropriately sized guide wires for the screws you plan to use for fixation. After inserting the guide wires, be sure to confirm placement on both anteroposterior (AP) and lateral radiographs. Once you have confirmed this, I recommend drilling, inserting the screws and then removing them prior to performing the osteotomy. This will allow for easy fixation placement after completing the osteotomy. 

Several studies highlight the utility of medial malleolar osteotomies. Leumann and colleagues noted that the optimal anatomic location at which to perform the osteotomy and reduce cartilage damage is at the medial curvature at the transition of the tibial plafond to the medial malleolus.¹ Although this approach proven useful in reducing cartilage damage, you want to make sure that your osteotomy will be large enough to gain visualization of the medial lesion.² You can study and plan for this preoperatively with computed tomography (CT) imaging. It is helpful to use a guide wire to define the apex of the chevron osteotomy and confirm placement with intraoperative fluoroscopy on AP and lateral views prior to performing the osteotomy. This enables surgeons to confirm how much of the tibial plafond will be affected. 

It is also important to reduce periosteal dissection to maintain blood supply. Begin the osteotomy with a saw under fluoroscopy parallel to the guide wire. Finish with an osteotome in order to reduce risk of injury to the talar cartilage. You can then reflect the distal malleolus inferiorly in order to gain access to the medial talar dome while keeping the deltoid ligaments intact. By doing so, you are protecting the blood supply to the medial malleolus. A toothed lamina spreader may be useful to reflect the malleolus and maintain visualization while treating the talar lesion. After repair of the talar lesion, one should reduce the medial malleolus anatomically and insert fixation screws. When performing a more vertical medial malleolar osteotomy, consider a buttress plate to avoid superior displacement and increase stability.^3,4 I will typically repair the thick periosteum over the osteotomy and the posterior tibial tendon sheath if I opened it intraoperatively.

When performing these osteotomies, it is important to recognize the potential associated risks including delayed union, nonunion and progressive arthritic joint degeneration.⁵ These osteotomies are not without complications but one can reduce the risk with attention to detail and appropriate use of fixation. 

Summarizing The Intraoperative Pearls

1. Protect the soft tissue structures anteriorly and posteriorly with Hohmann retractors.
2. Minimize periosteal dissection by only doing so at the osteotomy site.
3. Utilize a guide wire for the apex of the chevron osteotomy and confirm on AP and lateral fluoroscopic views prior to the osteotomy.
4. Pre-drill the screws prior to the osteotomy. 
5. Utilize fluoroscopy while performing the saw cuts.
6. Using a toothed lamina spreader may help increase exposure to the medial talus and allow you to retract the fragment.

Dr. Pirozzi is a Fellow of the American College of Foot and Ankle Surgeons (ACFAS), and serves as Vice President for ACFAS Region 2. She is in private practice in Phoenix, Ariz. 

References

1. Leumann A, Horisberger M, Buettner O, Mueller-Gerbl M, Valderrabano V. Medial malleolar osteotomy for the treatment of talar osteochondral lesions: anatomical and mobidity considerations. Knee Surg Sports Traumatol Arthrosc. 2016;24(7):2133-2139.

2. Navid DO, Myerson MS. Approach alternatives for treatment of osteochondral lesions of the talus. Foot Ankle Clin. 2002;7(3):635-649.

3. Jiang D, Zhan S, Wang Q, Ling M, Hu H, Jia W. Biomechanical comparison of locking plate and cancellous screw techniques in medial malleolar fractures: a finite element analysis. J Foot Ankle Surg. 2019;58(6):1138-1144. 

4. Tol JL, Struijs PA, Bossuyt PM, Verhagen RA, van Dijik CN. Treatment strategies in osteochondral defects of the talar dome: a systemic review. Foot Ankle Int. 2000;21(2):119-126.

5. Easley ME, Orr J, Nunley III JA. Osteochondral Autologous Transfer Procedure for Repairing Articular Cartilage Defects in the Talus: OATS Procedure. In: Kitaoka HB (ed.). Master Techniques in Orthopaedic Surgery: The Foot and Ankle, 3^rd edition. Philadelphia: Lippincott, Williams and Wilkins; 2013.