Treatment of Ankle Fractures with Open Reduction Internal Fixation via Improved Posterolateral Incision

Introduction

Injuries around the ankle are common, ankle fractures accounting for about 3.9% of all bone fractures and being top of the list of intra‐articular fractures1. In the USA, 26,000 patients with ankle fractures seek medical advice in each year and 25% of them require surgical treatment2. With the population aging and urban traffic becoming more diverse, the incidence of ankle fractures is increasing. The emphasis in surgical treatment of ankle fractures is on anatomical reduction and rigid fixation3. Open reduction and internal fixation is indicated for patients with posterior malleolus fracture fragments involving more than 25%–30% of the joint surface and dislocation more than 2 mm.

Case Presentation and Surgical Technique

A woman aged 64 years was admitted because of pain and movement dysfunction of the right ankle after a fall two hours previously and was found to have right ankle fractures (supination external rotation III degree). Her physical condition and medical history were unremarkable.

On clinical examination there were no skin damage or blisters around the ankle, the right lateral malleolus was significantly swollen, the anterior, lateral and posterior malleolus were very tender but there was no existed over the right medial malleolus. Grating of bone was palpable in the right lateral malleolus and the right ankle joint had a limited range of motion. A right ankle lateral radiograph, three‐dimensional CT scan and bone imaging resulted in a definite diagnosis of right ankle fractures (Lauge‐Hansen classification) supination external rotation III degree, (Danis–Weber/AO classification) type C1. The right lower limb was placed in a plaster cast and elevated. Ice compression was then applied and medication provided to reduce swelling. We confirmed that the optimal timing for surgery was when a dermatoglyphic sign appeared over the right ankle. Surgical treatment was undertaken with the patient's informed consent after performing routine preoperative tests to assess surgical risks. After preoperative discussion, a choice was made to use an improved posterolateral incision that is parallel to the fibular incision, 1 cm posterior to it, and with the distal end curved forward to the lateral malleolus; this allows treatment of both lateral and posterior malleolus fractures via a single incision. The procedure used is as follows: After anesthesia has been achieved, the patient is placed in a left lateral decubitus, disinfected drapes applied and the skin and subcutaneous tissue incised step by step, taking care to protect adjacent anatomic structures; in particular, the tendon of the peroneus longus and peroneus brevis located in the middle of incision, the fibula located posterior to the gap between the tendons of the peroneus longus and brevis, and the flexor hallucis longus adjacent to the tendon. The sural nerve is located anterior to the Achilles tendon and passes obliquely behind the lateral malleolus. The periosteal tissues around the fracture are thoroughly stripped and hematoma and other peripheral soft tissue debrided. While taking care to protect the sural nerve, anatomical reduction and internal fixation of first the lateral malleolus and then posterior malleolus fracture fragments is achieved with screws and plates under direct vision, the fracture of the lateral malleolus being exposed in the gap between the peroneus longus and peroneus brevis. First, two compression screws are used to pressurize and fix fractures. A 1/3 tubular plate is chosen and the fractures reshaped appropriately before placement of the plate. After the plate has been fitted, three screws are placed alternately on each end of it. The external malleolus is fixed, then the posterior malleolus. After exposure of the posterior malleolus fracture in the gap between the peroneus longus tendons and flexor hallucis longus, anatomical reduction and internal fixation with screws and T‐shape plate are achieved under direct vision. Next, C‐arm fluoroscopy is used to confirm accurate reduction of the posterior malleolus and ankle joint with smooth surface, after which a hollow screw is inserted to increase the stability of the posterior malleolus and compress the articular surface of the fracture to promote healing. It is important to ensure that the distal screw of the temporary fixation is loosened before applying compression with the hollow screw. Once the hollow screw is compressing the fracture line at the joint surface, the screw in the buttress plate can be retightened. There is still some controversy about fixation of distal tibiofibular syndesmosis.

In this patient, the operation time was 58 min, and blood loss was 20 mL. No postoperative complications occurred. The duration of follow‐up was 6 months. According to the American Orthopaedic Foot and Ankle Society score (94 points), fracture healing was achieved at 12 weeks, at which time the ankle function was assessed as optimal.

Discussion

At present, the most widely used classifications of ankle fractures are the Lauge–Hansen4 and AO classification based on the Danis–Weber classification5. The supination external rotation (SER) type accounts for about 40%–75% of ankle fractures6, SER III and IV degree being associated with posterior malleolus fractures. When the ankle has been sprained by strong vertical compression, there tend to be larger posterior malleolus fracture fragments. This 64‐year‐old patient had osteoporosis and the mechanism of injury included strong vertical compression strength after a fall from one meter high. She therefore had large posterior malleolus fracture fragments involving close to 50% of the joint surface. Posterior malleolus fractures must be anatomically repositioned; otherwise a smooth ankle surface cannot be guaranteed, especially when there is no direct exposure of the ankle surface to ensure that the cartilage is accurately aligned to achieve anastomosis. With the type of open reduction presented here, it is possible to ensure satisfactory reduction of posterior malleolus fracture fragments and use C‐arm fluoroscopy to determine whether anatomical restoration has been achieved. In terms of fixing posterior malleolus fractures, hollow screw can pressurize fractures involving the articular surface and thus promote fracture healing; however, in terms of biomechanical stability, a separately applied hollow screw is relatively weak and cannot adequately combat the vertical shear force of posterior malleolus fractures. Zhao et al. have reported that posterior malleolus buttress plate fixation achieves greater biomechanical strength than a separately inserted hollow compression screw nailed from front to back or vice versa7.

If there is an external malleolus fracture and the plan is to use a posterior anti‐slide plate, or if a posterior malleolus fracture has occurred in the posterior‐external tibia, a posterolateral incision over the ankle joint is appropriate. The classical posterolateral approach involves a 7 to 10 cm long longitudinal incision from the midpoint of the external malleolus and hamstring. The patient in the video was placed in a left lateral decubitus and our improved posterolateral incision used (parallel to the fibular incision, 1 cm posterior and curved forward distally toward the lateral malleolus). This improved incision is closer to the fibula and creates a smaller local skin flap than the traditional incision, resulting in less injury and better wound healing. We were able to reach the fracture by soft tissue dissection and achieve better exposure of the lateral and posterior malleolus, as well as treat both the lateral and posterior malleolus fractures via a single incision.

Fixation of distal tibiofibular syndesmoses is still controversial. At the Chinese Orthopedic Association conference in 2014, Professor Wang from Jishuitan Hospital concluded that three important complexes are involved in ankle joint stability. If two of them have been preserved, there is no need to fix the distal tibiofibular syndesmosis8. Because the structure of the medial malleolus of our patient was stable (supination external rotation III degree), after reduction and fixation of the fibula, two structures were stable; thus, the distal tibiofibular syndesmosis did not require fixation. Of course, the Cotton test can be used to further determine the stability of the distal tibiofibular syndesmosis and thus facilitate a decision about whether or not to perform fixation.

Postoperative radiography and CT confirmed complete anatomical repositioning of the surface of our patient's ankle fracture, which would have minimized her risk of developing postoperative traumatic arthritis. Because of the strong stability of the biomechanics of her ankle, postoperative exercises could be commenced early and her functional recovery was satisfactory, this mainly being attributable to our thorough preoperative assessment, appropriate operation design, correct timing of surgery, type of surgical incision and skill in performing the reduction and fixation.

Video Image

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Supporting information

Video Image