A Modied Posterolateral Approach for the Treatment of Posterior Malleolar Fracture

Background: To observe the clinical effect of a modied posterolateral approach internal xation in the treatment of posterior malleolar fracture. Method: From January 2015 to October 2018, 30 cases involving lateral and posterior malleolar fracture patient data were treated in our department. we observed operation time, fracture healing time and postoperative complications. At the time of the last follow-up, we evaluated ankle joint function by the American Orthopedic Foot Ankle Society (AOFAS) ankle- hindfoot scale, the Short Form-36 (SF-36) outcome Tools and the American Academy of Orthopaedic Surgeons (AAOS) Foot and Ankle Questionnaire. Result: In this group of 30 patients, the operation time of the patients was 80-120min (median 90min). The 25 patients were followed up for more than 1 year. 3 ~ 5 months after the operation, all the patients had bony healing. 3 cases with supercial wound infection. No other complication was found. The mean AOFAS scores at the postoperative 6-month, 12-month, and nal follow-up were 78.4 (range, 72–90), 89.4 (range, 80–96), and 90.8 (range, 84–96), respectively. The mean SF-36 scores at the postoperative 12-month and nal follow-up were 82.4 (range, 77.6–90.6) and 84.6 (range, 77.8–92.6), the mean AAOS scores at the postoperative 12-month and nal follow-up were87.8 (range, 79–95), 90.6 (range, 82–96). Conclusion: Modied posterolateral approach avoided stripping the muscular origins of exor hallucis longus, reduced the adhesion, and can x the lateral and posterior malleolar fracture in the same incision, is worth popularizing in that: trimalleolar stretch, can't hallux exion deformity, but when dorsiex the ankle, it hallux exion deformity.


Background
Ankle fracture is the most common fracture in orthopedic clinical work [1], and represent about one-tenth of all fractures [2]. Most foot and ankle orthopedist agree that posterior malleolus fragments worsen patient clinical outcomes [3][4][5]. In all ankle fractures, the incidence of posterior malleolus involvement ranges from 7 to 44% [2,6,7]. The surgical method and indication of posterior malleolus fracture are still controversial [7][8][9]. The size of posterior malleolus fracture ranges from shell-like fragments to fragments involving more than 40% of the distal tibia articular surface. Although most foot and ankle orthopedic surgeons agree that the fragments involving more than 25-30% of the surface of the distal tibial should be xed [10][11][12], there are still many surgeons believe that the surgical indications of posterior malleolar fragment should be expanded [8,[13][14][15]. When the posterior malleolar fragment size is small , it can be reduced and xed by minimally invasive approach, such as percutaneous reduction and cannulated screw xation [15]. When the posterior malleolus fracture is large enough, posterior buttress plate can provide more reliable xation [7]. Many ways have been described for open reduction and internal xation of posterior malleolus fracture [16][17][18][19][20], such as the posterolateral approach and posteromedial approach.
The entry of the posterolateral (PL) approach was through the interval between the exor hallucis longus muscles and the peroneal muscles. The attachment of the exor hallucis longus muscle will be strippinged from the bula sometimes. Then the exor hallucis longus muscle adhesion and hallux exion deformity will happen after operation. The posteromedial approach have been shown to expose the back of the ankle well [21], but the adjacent blood vessel and nerve may be injured by overstretching the soft tissues [19,22], and the fractures of the lateral malleolus require additional surgical incision. In recent years our team applied a modi ed posterolateral approach to expose the posterior malleolar fracture which can reduce damage to adjacent tissues.

Exclusion and Inclusion Criteria
This study reviewed a case series of ankle fracture involving posterior malleolar fracture and laternal malleolar fracture from January 2015 to October 2018. The inclusion criteria were (i) The age older than

Surgical Techniques
The injured ankle joint was xed by a brace which can help reduce swelling and alleviate pain. If combined with ankle subluxation or dislocation, and reduction was di cult to maintain, calcaneal traction will be given. When the swelling goes down, and the "wrinkle" sign appears, open reduction and internal xation will take place. After anesthesia, the patient was placed in a lateral prone position with the injured side facing up. Along with the posterior edge of the lateral malleolus and the middle point of the outer edge of the Achilles tendon , we make a longitudinal incision parallel to the outer edge of the Achilles tendon to the anterolateral arc of the lateral malleolus gure1 . Take care to protect the small saphenous vein and sural nerve. Exposing the underside of the Achilles tendon, the fascia on the surface of exor hallucis longus will be found. Cut the fascia and pull the exor hallucis longus to outside gure2 , posterior malleolus fracture will be found under the exor hallucis longus. The fracture lines can guide reduction of the posterior malleolar fragments, especially the medial fracture line and the top of the fracture line. After reduction, buttress plate was placed close to the joint line. Laternal malleolus fracture was xed by lateral anatomical plate, and medial malleolus fracture was xed by hollow screw.

Postoperative Protocol
In the rst 2 weeks postoperatively, the injured ankle joint was xed by a brace. Patients were advised to raise the limb and encouraged to activate the toes and the knee to help reduce swelling. The patients started ROM exercises after the brace was removed, and kept non-weight-bearing for 2 months. Patients begined partial weight bearing at 2 months after operation, with full weight bearing by 3 months.
Operative time, fracture healing time and postoperative complications were recorded, Postoperative Xrays were performed at the rst week after surgery, 1-month, 3-month, 6-month, 12-month to Judge fracture healing. We evaluated the functions of all patients using American Orthopedic Foot and Ankle Society (AOFAS) scores at the 6-month, 12-month and nal follow-up [24], using the Short Form-36 (SF-36) outcome Tools and the American Academy of Orthopaedic Surgeons (AAOS) Foot and Ankle Questionnaire at the 12-month and nal follow-up visits [25][26] ,

Results
In this group, the operation time of the patients was 80-120min (median 90min). A total of twenty-ve of the thirty patients in our study were followed up for 12 to 18 months, with a median of 14 months. All cases healed 3 ~ 5 months after the operation.

Discussion
The indications for surgical treatment of posterior malleolar fracture remain a controversy [7][8][9]. Fragment size of the posterior malleolar fragment still affected treatment decisions [8,27,28]. As routinely, fragments of the posterior malleolus which are more than 25%-30% of the distal tibia articular surface will be treated surgically [10][11][12]28]. However, a lot of recent literature argue that surgical xation of small fragments of the posterior malleolus may have a better effect on the clinical effects [8,13,15]. And also, posterior malleolus xation relates to syndesmotic stability [14,[28][29][30]. Then it may allow an opportunity to avoid standard syndesmotic xation with screws, which bring about many complications[31].
Many surgical approaches both direct and indirect reduction have been reported [7,19]. Indirect percutaneous reduction and hollow screw xation is minimally invasive surgery, but it does not allow adequate visualization of the fragment to reduce the displaced posterior malleolus fragment. Studies have shown that this technique does not achieve the same level of anatomic reduction of the posterior malleolus as direct reduction [7]. Some posterior approach have reported in the literatures, such as the posterolateral approach and posteromedial approach [16][17]. The posteromedial approach, which near the ankle tube, the neurovascular bundle may be injuried by traction when operation. And it provides excellent visualization of the medial two-thirds of the posterior malleolus, but cannot provide visualization and exposure of the lateral one-third, syndesmosis, and bula, which are always involved in trimalleolar fracture [19]. The posterolateral approach which hinges on the peroneal tendons laterally and the exor hallucis longus muscle medially,can permit safe exposure of approximately onehalf of the posterior malleolus, but the achilles tendon and the exor hallucis longus muscle belly make it di cult to get more medial [19]. And if you want to expose more widely and proximally, the attachment of the exor hallucis longus muscle will be strippinged from the bula, then the exor hallucis longus muscle adhesion and hallux exion deformity may happen after operation ( gure 3). A modi ed posteromedial approach had been reported in the literature [16],which hinges on the tibialis posterior and exor digitorum longus and neurovascular bundle medially, and the exor hallucis longus muscle and tendon laterally. It can provide a good exposure of the the distal posterior malleolus [19], bu tIt does not expose the bula fracture .
Our approach is a hybrid-type of the posterolateral approach and the modi ed posteromedial approach. It combines the advantages of the two approaches. The skin incision is same to the posterolateral approach which is along with the middle point of the outer edge of the Achilles tendon and the posterior edge of the lateral malleolus. The inside tissue space learns from the modi ed posteromedial approach, which expose the posterior malleolar fracture between the exor hallucis longus and neurovascularbundle. Firstly, it is able to reduce and x both the posterior and lateral malleolus fractures by one skin incision; secondly, it will help to reduce the damage to the exor hallucis longus when exposing posterior malleolar fracture, then the exor hallucis longus muscle adhesion and hallux exion deformity will be avoided; thirdly, It permits exposure of the Similar range of the distal posterior malleolus to the modi ed posteromedial approach. Especially, it can well expose the inner margin of the fracture block of posterior malleolus, which play an important role in reducing posterior malleolus fracture anatomically.

Conclusions
In our case series, we reduced and xed both the posterior and lateral malleolus fractures by the modi ed posterolateral approach successfully, and the complications were rare. We believe that the modi ed posterolateral approach is a surgical approach worth popularizing.
This study is our rst report of this modi ed posterolateral approach. Our aim was to provide a new modi ed posterolateral approach that can help the surgeon expose the lateral and posterior malleolus well. At the same time, the injury to hallux long exor muscle is reduced. It has some limitations, such as a small sample size, retrospective study design,no control group. We need future prospective cohort studies and randomized controlled clinical trials with a big sample size.  Figure 1 the incision of the modi ed posterolateral approach Figure 2 pull the exor hallucis longus to outside we can see the area in where we place the plate and screw. Figure 3