25 Medializing Calcaneal Osteotomy Abstract The medializing calcaneal osteotomy is a frequently performed procedure usually done in conjunction with a flexor tendon transfer as part of a flatfoot correction surgery. By sliding the posterior tuber of the calcaneus 1 cm medially, the mechanical axis of the limb is medialized, thereby decreasing the stress on the posterior tibial tendon’s mechanics to invert the hindfoot. Additionally, the Achilles tendon insertion is medialized, converting the gastroc-soleus complex into a true plantar flexor and not a hindfoot evertor as occurs when the hindfoot is in valgus. This procedure has a high union rate and is technically reproducible. Keywords: calcaneal osteotomy, medializing, valgus • As part of flatfoot deformity correction: • To medially shift mechanical axis of limb to unload lateral ankle joint. • Standing patient viewed from behind: valgus hindfoot alignment > 5 degrees. • Flexible hindfoot valgus: corrected with a reverse Coleman block test/passive hindfoot inversion of subtalar joint. • Weight-bearing anteroposterior and lateral radiographs of foot. • Saltzman’s alignment view demonstrating hindfoot valgus. • Medially posted orthotics. • Ankle foot orthosis (Arizona brace). • Hindfoot arthritis. • Fixed flatfoot deformity. • Severe flatfoot with Meary’s angle >30 degrees/TN uncoverage >40%. • The goal of the procedure is to stably change the biomechanical axis of the hindfoot. By shifting the calcaneal tuber medially, the posterior leg of the tripod making up the foot is moved medially. This can change the weight-bearing axis of the lower extremity. By doing so, the forces placed across the subtalar joint and to a lesser degree the ankle joint can be changed. In addition, the line of pull of the Achilles tendon is medialized. • Advantages of this procedure are that it is relatively easy to perform, has low morbidity, and has a high rate of success. • Lateral incision over calcaneus inferior to the peroneal tendons. • Oblique osteotomy of the posterior calcaneal tuberosity anterior to a line between the Achilles insertion and the plantar fascial insertion. • Distraction of the osteotomy. • Medial translation of the posterior calcaneal tuber 1 cm. • Rigid fixation of the osteotomy with cannulated screw. • Preoperative preparation should include the planning of the equipment to be used. • A list of the equipment that may be required includes • The patient is placed in a supine position on the operating table. A bump should be placed underneath the ipsilateral hip to facilitate internal rotation of the operative extremity. This type of positioning allows for the surgeon to work over both the lateral and the medial aspects of the foot. This is very useful when performing an acquired flatfoot deformity (AAFD) reconstruction involving both bony and soft-tissue work, such as tendon transfers. • Alternatively, a lateral position can be used. This makes access to the medial aspect of the ipsilateral foot more difficult but in some cases, may be desirable if the medializing calcaneal osteotomy (MCO) is done without the need for additional procedures, and the amount of assistance available during the case is limited. • After the patient has been placed on the table, a bump is placed underneath the ipsilateral hip. This should allow easy access to the lateral heel. A stack of folded blankets for a commercially available foam ramp to the pool lower extremity above the nonoperative contralateral side can be helpful. • The last step before prepping should be placement of a high thigh tourniquet on the ipsilateral lower extremity. Alternatively, a sterile tourniquet may be placed on the midportion of the leg if desired. • The patient then undergoes a standard prep and drape of the lower extremity. The lateral hindfoot is then palpated in an effort to try and localize the superior and inferior orders of the calcaneal tuber. This is fairly easy on most patients but may be more difficult with in those with a high body mass index. Also, if possible, palpation of the sural nerve is performed. If the surgeon is able to identify the nerve, its path may be marked with a surgical marker. In the event that the sural nerve cannot be palpated, the line of the incision is made approximately midway between the tip of the fibula and the posterior border of the calcaneus. The incision should be aligned perpendicular to the long axis of the calcaneal tuber. The length of this incision does not need to be much longer than the superior/inferior thickness of the calcaneal tuber (Fig. 25.1). • The skin is then incised. Care should be taken to identify the sural nerve in the subcutaneous tissues. Once this has been identified, the nerve is then retracted superiorly to give better access to the lateral wall of the calcaneus. Once the nerve has been protected and moved out of the way, dissection can be carried out straight to the lateral wall of the calcaneus. • A small soft-tissue elevator can be used to create a 2-mm channel in the periosteum (Fig. 25.1). After this has been done, the sagittal saw is used to create the osteotomy. This should be perpendicular to the long axis of the calcaneal tubercle. Care should be taken not to plunge through the medial cortex of the calcaneus. If possible, we choose to finish the osteotomy through the medial portion of the calcaneus using an osteotome. • After completion of the osteotomy, the fragments need to be distracted to allow stretching of the soft tissues and compliance of the soft tissues. This greatly eases the translation of the posterior fragment. Osteotomes can be used to start this process (see below). • A smooth laminar is inserted and the osteotomes are removed. Arms of the laminar spreader should be inserted deeply enough to allow the tip to slightly overhang the medial cortex of the osteotomy site. This allows for optimal cortical support of the arms of the laminar spreader during distraction of the osteotomy fragment and prevents compaction of the soft cancellous bone (Fig. 25.2). A second osteotome may also be placed within the osteotomy site. After both laminar spreaders have been inserted, they are expanded to allow distraction of the posterior calcaneal fragment from the main body of the calcaneus. Distraction should be at least 1-cm wide. This position is held for a few minutes to allow the soft tissues to gently stretch. This stretching will facilitate easy translation of the calcaneal fragment prior to fixation. • After a few minutes of distraction, a guide pin may be inserted into the posterior calcaneal osteotomy fragment in preparation for provisional fixation of the osteotomy after translation has been obtained. If this is done, the pin is inserted approximately 5 to 7 mm medial to the lateral cortex of the posterior fragment and slightly inferior in the fragment as well (Fig. 25.3). This positioning allows for advancement of a lag screw beyond the osteotomy site and into the anterior process of the calcaneus without breaching the medial cortex and potentially harming the medial neurovascular structures. This screw position gives excellent purchase especially in patients who have a relatively short calcaneal tuber in which it may be difficult to fully advance all the threads of a partially threaded screw across the osteotomy site.
25.1 Indications
Together with flexor digitorum longus (FDL) transfer for posterior tibial tendon reconstruction.
Stage 2A flatfoot.
25.1.1 Clinical Evaluation
25.1.2 Radiographic Evaluation
Flatfoot deformity with Meary’s angle > 4 degrees but < 30 degrees.
Talonavicular (TN) uncoverage of 20 to 40%.
Absence of hindfoot (subtalar/TN) arthritis.
25.1.3 Nonoperative Options
25.1.4 Contraindications
25.2 Goals of Surgical Procedure
25.3 Advantages of Surgical Procedure
25.4 Key Principles
25.5 Preoperative Preparation and Patient Positioning
Sagittal saw/micro-sagittal saw.
Self-retaining retractor.
Cannulated screws or a specially designed fixation plate.
Bone tamp.
Mallet.
Absorbable monofilament sutures.
Skin stapler.
25.6 Operative Technique
Musculoskeletal Key
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