Operative Techniques in Orthopaedic Surgery (4 Volume Set) 1st Edition

502. Chevron-Type Medial Malleolar Osteotomy

Bruce Cohen

DEFINITION

images Lesions of the medial talar dome can be very challenging to manage operatively, particularly as they tend to be located in the central or posteromedial aspect of the ankle and are often difficult to access or visualize.

images Various techniques have been described to provide adequate or improved exposure for posteromedial talar dome lesions. Options include arthroscopic techniques, standard arthrotomy, tibial grooving, or medial malleolar osteotomy.

images With the recent interest in new techniques for the treatment of osteochondral lesions of the talar dome, appropriate exposure of both medial and lateral talar dome lesions has become very important.

images Osteochondral allograft insertion and other cartilage replacement techniques are moving to the forefront of orthopaedic foot and ankle care and rely on adequate exposure of the lesion itself. The chevron-type medial malleolar osteotomy is a very stable, reproducible osteotomy that allows excellent exposure to the tibiotalar joint.

ANATOMY

images Pertinent anatomy related to osteotomies of the medial malleolus includes the adjacent structures such as the posterior tibialis tendon and the adjacent neurovascular bundle. The medial malleolus is subcutaneous and convex on its medial border and slightly concave on its lateral surface. The posterior surface includes the malleolar sulcus, which contains the posterior tibialis tendon and the flexor digitorum longus tendon. The distal portion contains the attachment of the deltoid ligament.

PATHOGENESIS

images Lesions of the medial talar dome that require treatment by adjunctive osteotomy include talar body fractures, osteochondral lesions of the talar dome, and other intra-articular lesions.

NATURAL HISTORY

images Advantages proposed for the use of a medial malleolar osteotomy include excellent visualization and wide exposure for débridement or fixation of fragments. Possible disadvantages include the need for prolonged postoperative immobilization and the risk of degenerative ankle arthrosis or nonunion, as well as prominent hardware. No previous study has specifically addressed the results and the morbidity of a medial malleolar osteotomy.

IMAGING AND OTHER DIAGNOSTIC STUDIES

images Standard ankle radiographs are mandatory. Intra-articular lesions, including talar fractures and osteochondral lesions of the talus, can be evaluated with MRI or CT scans.

SURGICAL MANAGEMENT

Preoperative Planning

images Preoperative planning primarily focuses on the planning required for the talar lesion, or fracture, that is being addressed. For comminuted talar body fractures, preoperative CT scans are essential not only for planning the potential fixation but also for evaluating the extent of the articular injury.

images In planning for the treatment of osteochondral lesions, MRI techniques can be helpful in evaluating the size and location of the lesion and the extent of articular involvement and screening for other articular abnormalities.

images CT scans can be helpful in determining the presence of cystic lesions and especially determining whether the lesion is “contained” and appropriate for consideration of osteochondral transplantation.

Positioning

images The patient is positioned supine.

Approach

images A standard medial approach is used, with the incision centered on the medial malleolus and slightly curved distally. Care is taken to avoid injury to the saphenous vein and nerve.

TECHNIQUES

CHEVRON-TYPE MEDIAL MALLEOLAR OSTEOTOMY

images  A chevron-type transmalleolar osteotomy is performed in the following manner.

images  After standard exposure of the medial malleolus, open the posterior tibialis tendon sheath at the level of the ankle mortise.

images  Retract the posterior tibialis tendon itself and protect it posteriorly.

images  Predrill and tap the medial malleolus with a 2.5-mm drill.

images  Make the chevron-shaped osteotomy with a microsagittal saw. The apex is directed proximally and the limbs of the chevron are extended from the mortise level (TECH FIG 1A,B). In the AP plane, the osteotomy is angled toward the junction of the medial malleolus and tibial plafond articular surface (TECH FIG 1C).

images  Complete the osteotomy with a fine hand osteotome, avoiding a “Kerf” effect within the joint.

images  Retract the osteotomized medial malleolus, releasing anterior and posterior soft tissues as necessary for exposure of the talar dome while maintaining the superficial and deep attachments of the deltoid ligament (TECH FIG 2).

images  At the conclusion of the procedure, stabilize the osteotomy using two 4.0-mm partially threaded cancellous screws (Synthes, USA) (TECH FIG 3).

images

TECH FIG 1  A. Incision for medial malleolar osteotomy. Chevron-type medial malleolar osteotomy in (B) lateral plane and (C) AP plane.

images

TECH FIG 2  Intraoperative pictures of osteotomy.

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TECH FIG 3  Postoperative radiographs, AP view.

images

POSTOPERATIVE CARE

images The patient is placed in a plaster splint for 10 to 14 days postoperatively. Active range of motion is begun after 10 to 14 days (or when the wound has sealed) and the patient is placed in a removable short-leg cast brace. Non–weightbearing ambulation is maintained until radiographs, repeated at about 6 weeks, confirm maintenance of reduction.

OUTCOMES

images A retrospective review was performed on 19 patients who underwent medial malleolar osteotomy for the treatment of pathology of the talar dome.6 Chart review, radiographic examination, and clinical examination were performed in all patients. Fifteen patients had osteochondral lesions of the medial talar dome. All patients failed conservative treatment of these lesions, including a period of immobilization and anti-inflammatory medication. The location of the lesion was in the posterior or central portion of the talar dome in all patients.

images Three patients had medial malleolar osteotomy performed for exposure during internal fixation of displaced talar dome fractures. One additional patient had curettage and bone grafting of a large medial talar cyst.

images About 50% of the patients had undergone prior surgery on the affected ankle. Six patients had a total of nine prior arthroscopic procedures. The average age of the patients was 32 years (range 14 to 51). The length of follow-up was 12 months (range 6 to 43).

images All patients achieved union of the osteotomy both clinically and radiographically. The average time to radiographic union was 7 weeks (range 5 to 12). No failures of fixation were noted.

images Preoperative and postoperative tibiotalar range of motion was measured. At the last follow-up, only 2 of 19 patients had any loss of motion compared to their preoperative evaluation. This decreased range of motion was about 10 degrees of total arc of motion.

images Four patients had slight (less than 2 mm) displacement at the osteotomy site. This displacement was noted immediately postoperatively and was felt to be due to technical errors during the bone cuts for the osteotomy. No progressive displacement was noted in these patients. All four patients were asymptomatic at the osteotomy site and no progressive ankle arthrosis was noted. Three patients had symptomatic prominent screws that resulted in hardware removal. All the screws were removed as an outpatient procedure under a local anesthetic without complications. No postoperative complications, including infection, nonunion, or delayed wound healing, were noted in the study population.

COMPLICATIONS

images Nonuion rates for medial malleolar osteotomy are reported as high as 12%. Theoretically the chevron-type provides excellent stability for fixation.

images Other complications include saphenous nerve injury, with resulting medial ankle numbness or painful subcutaneous neuroma, or posterior tibial tendon laceration, resulting in displacement of the osteotomy and development of progressive arthrosis.

REFERENCES

1.     Alexander AH, Lichtman DM. Surgical treatment of transchondral talar-dome fractures (osteochondritis dissecans). J Bone Joint Surg Am 1980;62A:646–652.

2.     Alexander IJ, Watson JT. Step-cut osteotomy of the medial malleolus for exposure of the medial ankle joint space. Foot Ankle Int 1991;11:242–243.

3.     Berndt AL, Harty M. Transchondral fractures (osteochondritis dissecans) of the talus. J Bone Joint Surg Am 1959;41A:988–1020.

4.     Bryant DD, Siegel MG. OCD of the talus: a new technique for arthroscopic drilling. Arthroscopy 1993;9:238–241.

5.     Canale ST, Belding RH. Osteochondral lesions of the talus. J Bone Joint Surg Am 1980;62A:97–102.

6.     Cohen BE, Anderson RB. Chevron-type transmalleolar osteotomy: an approach to medial talar lesions. Tech Foot Ankle Surg 2002;1: 158–162.

7.     Ferkel RD, Fasulo GJ. Arthroscopic treatment of ankle injuries. Orthop Clin North Am 1994;25:17–32.

8.     Flick AB, Gould N. Osteochondritis dissecans of the talus (transchondral fractures of the talus): review of the literature and new surgical approach of medial dome lesions. Foot Ankle 1985;5:165–185.

9.     Gepstein R, Conforty B, Weiss RE, et al. Closed percutaneous drilling for osteochondritis dissecans of the talus. Clin Orthop Relat Res 1986;213:197–199.

10. Kristensen G, Lind T, Lavard P, et al. Fracture stage 4 of the lateral talar dome treated arthroscopically using Biofix for fixation. Arthroscopy 1990;6:242–244.

11. McCullough CJ, Venegopal V. OCD of the talus: the natural history. Clin Orthop Relat Res 1979;144:264–268.

12. O’Farrell TA, Costello BG. OCD of the talus: the late results of surgical treatment. J Bone Joint Surg Br 1982;64B:494–497.

13. Ove N, Bosse MJ, Reinert CM. Excision of posterolateral talar dome lesions through a medial transmalleolar approach. Foot Ankle 1989; 9:171–175.

14. Parisien JS. Arthroscopic treatment of osteochondral lesions of the talus. Am J Sports Med 1986;14:211–217.

15. Ray RB, Coughlin EJ. Osteochondritis dissecans of the talus. J Bone Joint Surg Am 1947;29A:697–706.

16. Roden S, Tillegard P, Unanderscharin L. Osteochondritis dissecans and similar lesions of the talus. Acta Orthop Scand 1953;23: 51–52.

17. Scharling M. Osteochondritis dissecans of the talus. Acta Orthop Scand 1978;49:89–94.

18. Thompson JP, Looner RL. Osteochondral lesion of the talus in a sports medicine clinic: a new radiographic technique and surgical approach. Am J Sports Med 1984;12:460–463.

19. Yvars MF. Osteochondral fracture of the dome of the talus. Clin Orthop Relat Res 1976;114:185–191.



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