Arthroscopic Treatment of a Malunion of a Posteromedial Tubercle Fracture of the Talus.

Posteromedial ankle impingement is rare and uncommonly associated with a fracture. Bone resection of the fragment is the recommended treatment. In this report, we describe the step-by-step surgical technique of arthroscopic resection of a malunion of a posteromedial talus fracture to correct the impingement.

Cedell described talus fracture in 4 young active sportsmen in 1974. These injuries are rare, and from then until now, only a few cases have been reported. The patient may arrive in the emergency department with pain and tenderness in the posteromedial region of the talus. However, most of the time, the injury's similarity to an ankle sprain on normal anteroposterior and lateral ankle radiographic views may contribute to misdiagnosis or delayed diagnosis.

Different treatments of this injury are supported in the literature: conservative treatment of nondisplaced or minimally displaced fractures, open reduction–internal fixation for displaced fractures, or fracture excision for malunion of displaced fractures that cause posteromedial ankle impingement.2, 3

Technique

The diagnosis can be made using anteroposterior and lateral ankle radiographs (Fig 1) and computed tomography (Fig 2).

Fig 1

Preoperative anteroposterior and lateral radiographs of a right ankle showing a posteromedial talus fracture (arrow).

Fig 2

Preoperative 3-dimensional right ankle reconstruction showing a displaced posteromedial talus fracture with malunion (arrow).

Preoperative Setup

The patient is placed in the prone position with application of a thigh tourniquet to provide a bloodless surgical field. All bony prominences are padded. A small support is situated under the lower leg, making it possible to move the ankle freely. The ankle should be kept in a plantar-flexed position to relax the neurovascular bundle. The operative leg is prepared and draped in standard fashion. No traction is required.

Portal Placement

According to the recommendations of Van Dijk et al, the posterolateral portal is created through an incision at the level of or slightly above the tip of the lateral malleolus, just lateral to the Achilles tendon. Careful palpation of the Achilles tendon before portal insertion reduces the risk of damaging the tendon. Blunt dissection to the level of the joint is carried out with a small mosquito clamp directed anteriorly, pointing in the direction of the interdigital web space between the first and second toes. It is exchanged with a 4.5-mm arthroscope shaft (Arthrex, Naples, FL) with a blunt trocar.

The posteromedial portal is made just medial to the Achilles tendon, at the same level as the posterolateral portal. A mosquito clamp is introduced and directed toward the arthroscope shaft at 90° to touch this shaft; it should pass the neurovascular bundle without a problem. A 4.0-mm 30° arthroscope (Arthrex) is used through the posterolateral portal. The posterolateral portal is used as the viewing portal, and the posteromedial portal serves as the working portal (Fig 3). If there is any difficulty in determining whether the arthroscope is inserted correctly, confirmation of its position by fluoroscopy is recommended.

Fig 3

The patient is in the prone position. Portal placement is shown for the right ankle. Placement of the posterolateral portal is performed just lateral to the Achilles tendon at the level of the tip of the malleolus. A 4-mm 30° arthroscope is in position. The posteromedial portal is made just medial to the Achilles tendon, at the same level as the posterolateral portal. A shaver is introduced and directed toward the arthroscope shaft.

Surgical Correction of Posterior Ankle Impingement

Before the surgeon addresses the pathology, it is paramount to identify the flexor hallucis longus (FHL) and confirm that it moves with passive motion of the hallux. A base loop is passed around the tendon. The FHL is used as the medial border of the working area, which helps prevent injury to the neurovascular bundle. Then, debridement starts with an arthroscopic shaver (Arthrex) and radiofrequency device (Arthrex) inserted through the posteromedial portal.

When soft-tissue debridement is complete, the fracture malunion is clearly defined (Fig 4). Then, it is time to perform resection. This may include partial or total resection to correct the impingement (Fig 5). We perform partial resection of the fragment with a motorized 4.0-mm burr (Arthrex) to restore the normal shape of the posterior talus. We check, under arthroscopic control, that range of ankle motion is completely restored and posterior ankle impingement is corrected (Fig 6).

Fig 4

Arthroscopic view of the posteromedial aspect of the right ankle from the posterolateral portal. The fracture malunion (yellow arrow) and posterior ankle impingement are visualized. A shaver is introduced through the posteromedial portal. The flexor hallucis longus is on the medial side with a base loop around it (green arrow).

Fig 5

Arthroscopic view of the posteromedial aspect of the right ankle from the posterolateral portal. Partial resection of the fracture malunion (arrow) is performed. A burr is introduced through the posteromedial portal.

Fig 6

Arthroscopic view of the posteromedial aspect of the right ankle from the posterolateral portal. Final reshaping of the posterior talus is performed, and posterior ankle impingement (red arrow) is corrected. The flexor hallucis longus is on the medial side with a base loop around it (green arrow).

Complications

Although we have not encountered any complications with this procedure, the major complication is injury to the tibial neurovascular bundle. It is recommended to keep the ankle in plantar flexion during the procedure and keep the instruments lateral to the FHL.

Postoperative Rehabilitation Protocol

The patient is discharged on the day after surgery using crutches. Weight bearing is allowed. A rehabilitation program to gain full mobility and strength is followed. A control computed tomography scan is ordered 1 month after surgery (Fig 7). Return to sports is gradually permitted, based on functional demands, with the most demanding activities being avoided until 3 months after ankle arthroscopy.

Fig 7

Three-dimensional reconstruction 1 month after arthroscopic resection of a malunion of a posteromedial talus fracture showing correction of posterior ankle impingement (arrow).

A step-by-step summary of our technique is provided in Table 1. Pearls and pitfalls are presented in Table 2, and advantages and disadvantages are listed in Table 3. Key steps of the procedure are shown in Video 1.

Table 1

Step-by-Step Summary of Arthroscopic Treatment of Malunion of Posteromedial Talus Fracture

1. Position the patient in the prone position with application of a thigh tourniquet to provide a bloodless surgical field. 2. Keep the ankle in a plantar-flexed position to relax the neurovascular bundle. 3. Establish the posterolateral and posteromedial portals. 4. Use a 4-mm 30° arthroscope inserted through the posterolateral portal. 5. Identify the FHL and confirm that it moves with passive motion of the hallux. 6. Start debridement with an arthroscopic shaver and radiofrequency device inserted through the posteromedial portal. 7. Identify the fracture malunion. 8. Perform partial resection of the fragment with a motorized 4.0-mm burr. 9. Check, under arthroscopic control, that range of ankle motion is completely restored and posterior ankle impingement is corrected.

FHL, flexor hallucis longus.

Table 2

Pearls and Pitfalls

Pearls	Pitfalls
Use the prone position; pad all bony prominences.	Pressure sores and lateral femoral cutaneous nerve neuropathy
Note that no traction is required.	No free movement of ankle
Keep the ankle in a plantar-flexed position.	Neurovascular bundle injury
Perform careful palpation of the Achilles tendon.	Achilles tendon injury
Identify the tip of the lateral malleolus for correct portal placement.	Incorrect portal placement
Use the arthroscope shaft as a guide to place the posteromedial portal.	Neurovascular bundle injury
Use fluoroscopy to confirm the position and direction of the arthroscope if necessary.	Incorrect portal placement
Identify the FHL by passive motion of the great toe and pass a base loop around the tendon.	Neurovascular bundle injury
Perform a detailed examination of posterior ankle impingement.	Incorrect portal placement
Identify the fracture malunion.	No identification of fracture malunion
Reshape the posterior talus.	No impingement correction
Avoid excessive bone resection.	Excessive bone resection leading to ankle instability
Check complete ankle motion and correction of posterior ankle impingement.	No improvement in clinical results

Table 3

Advantages and Disadvantages

Advantages

The procedure allows excellent access to the posterior ankle compartment.

The procedure is minimally invasive.

The procedure allows posterior ankle impingement to be corrected.

The recovery time is shorter.

Disadvantages

The technique is challenging.

Neurovascular bundle injury can occur.

An experienced arthroscopist is required.

The operative time is longer.

Discussion

Posteromedial talus fracture has a potential for delayed diagnosis.2, 3, 5 First, it is a rare injury. Second, it shows similarity to an ankle sprain on standard ankle radiographs. To avoid future morbidity, it is important to diagnose this fracture at the time of the initial presentation.

Careful clinical and radiographic evaluation is required to obtain a prompt diagnosis. Tenderness over the deltoid ligament on physical examination should raise suspicion. If no abnormal findings are observed on routine trauma views of the ankle, a more precise examination should be scheduled. Ebraheim et al. described, in a cadaveric study, the utility of a 30° external rotation view of the ankle as a radiologic method to diagnose a posteromedial tubercle fracture of the talus. They recommended its use with the 3 routine trauma views of the ankle.

A computed tomography scan and magnetic resonance imaging should be requested if radiographic evaluation findings are normal. Malunion of a posteromedial fracture might be the cause of posteromedial ankle impingement and persistent posteromedial ankle pain. Bone excision is recommended in these cases.2, 3, 7

Open surgical treatment through a posteromedial approach has the risk of damaging the neurovascular structures. If it is necessary to improve visualization of the ankle and subtalar joints, an external fixator should be placed intraoperatively. Often, open surgical treatment is followed by a short period of immobilization. The arthroscopic approach has many advantages. It is a surgical procedure with less morbidity. It offers good access to the posterior ankle compartment. Malunion of a posteromedial fracture can be visualized and treated, and no immobilization is required.2, 4 We recommend this surgical procedure to perform a partial resection of a malunion of a posteromedial fracture to correct posterior ankle impingement.