Arthroscopic findings and treatment of maisonneuve fracture complex

Background The Maisonneuve fracture complex (MFC) is a well-known lower leg injury. However, the optimal treatment is still not clear and there is limited data on concomitant injuries of cartilage. Therefore, the aim of our study was to report the incidence of incidental cartilage injuries and their management in arthroscopic treatment of MFC. Patients and methods Between February 2018 and February 2021 all patients presenting with MFC in our department were treated with diagnostic ankle arthroscopy and percutaneous syndesmotic screw or suture-endobutton fixation. In case of instable cartilage, it was debrided and according to the International Consensus Meeting on Cartilage Repair of the Ankle, in grade IV lesions < 10 mm or < 100 mm2 area the subchondral bone was microfractured. Results Eighteen patients, 16 male and two female, with a mean age of 48.1 years, were included. In all cases, instability of the distal tibiofibular articulation was confirmed arthroscopically. Injuries of the cartilage were found in 56% of the cases and in 31% of the patients surgical intervention was required. In three talar and one tibial lesion additional arthroscopic bone marrow stimulation with microfracture of the subchondral bone was performed. Conclusions Ankle arthroscopy is a helpful method to guide fibular reduction and to detect and address associated cartilage injuries. Due to the high rate of chondral lesions, addressing these arthroscopically may contribute to better postoperative results. Level of evidence IV


Introduction
"La fracture du péroné", or better known as Maisonneuve fracture complex (MFC) was first described by the French surgeon Jacques Gilles Maisonneuve in 1840 [1]. The injury typically consists of a fracture of the proximal fibula with disruption of the distal tibiofibular syndesmosis and a deltoid rupture or medial malleolus fracture.
The mechanism of the injury was described by Pankovich as a strong external rotation force with the foot in slight supination and in neutral or slight pronation in later stages [2].
Regarding therapy, some authors reported of nonoperative treatment: Pankovich [2] treated the MFC nonoperatively in cases without rupture of the deltoid ligament, interosseous ligaments, or medial malleolus fracture and Merrill [3] suggested that these are often more stable than generally assumed. According to the Lauge-Hansen classification, this could be possible, but sometimes it is difficult to differentiate between partially and total ruptured syndesmotic ligaments preoperatively. Therefore, MFC should be assumed as an unstable injury, and most authors recommend operative treatment [4][5][6][7][8][9]. Stufkens [9] for treatment of Maisonneuve fractures: the medial  malleolus should be fixated, the torn deltoid ligament  need not be directly repaired, syndesmotic instability can  be treated with one or two 3-or 4-cortical screws which can be placed percutaneously, and the proximal fibular fracture does not require direct internal fixation. However, the optimal operative management is not clear and various options are under debate.
Moreover, Hintermann [10] and Loren [11] reported of an incidence of cartilage lesions, including chondral defects and osteochondral lesions, in ankle fractures of 79.2%, respectively 63%. Yoshimura [8] reported that all patients with MFC, who underwent ankle arthroscopy, had cartilaginous damage to the medial section of the talar dome. Therefore, we started to treat patients with Maisonneuve fracture arthroscopically to detect and address concomitant injuries. The aim of this study was to retrospectively evaluate the incidence of cartilage injuries in these patients.

Materials and methods
Between February 2018 and February 2021 all 18 patients presenting with MFC, 16 men and two women, were treated consecutively with ankle arthroscopy in our department. The mean age at time of surgery was 48.1 years (range 23 to 74 years). Eleven MFCs were sports related, six occurred as a result of an ankle sprain while walking, and one patient had a motorcycle accident (Table 1).
MFC was confirmed with radiographs of the ankle and knee. In 5 patients an additional CT-scan and in 3 patients an MRI of the ankle was performed.
Preoperatively, prophylactic antibiotics were given intravenously. All Arthroscopies were performed or attended by a national-board certified foot and ankle surgeon in spinal anaesthesia and tourniquet control. Therefore, patients were set in supine position, no ankle distractor was applied, and saline was injected to inflate the ankle joint. Routinely, a 4 × 152.5 mm/30° arthroscope with standard anteromedial and anterolateral portals was used to access the ankle.
An anterior ankle examination, as described by Ferkel [12], was used to verify syndesmotic instability and to check for cartilage injuries. External rotation stress test was used to assess syndesmotic injury. Frank syndesmosis instability was defined by ≥2 mm displacement of the lateral malleolus ( Fig. 1) [13]. Lesions of the cartilage were classified according to the International Cartilage Repair Society (ICRS) grading system [14].
Instable cartilage was debrided and, as recommended by the International Consensus Meeting on Cartilage Repair of the Ankle, in lesions < 10 mm or < 100 mm 2 area subchondral bone was microfractured [15].
After addressing cartilage damage, avulsed ligaments and debris of the distal tibiofibular syndesmosis was resected with a 4 mm shaver to allow proper positioning of the fibula into the incisura. Closed reduction was performed with a sharp reduction clamp and controlled arthroscopically and fluoroscopically. Length to the fibula was restored and internal rotation as well as medial translation was assessed. Fixation of the fibula was either achieved with percutaneous placement of two tricortical 3.5 mm stainless steel screws or suture-endobuttons (TightRope ® , Arthrex, Naples, FL).
Medial malleolar fractures were addressed with open reduction and screw fixation, whereas deltoid ligament disruptions were treated non-operatively in the context of postoperative immobilization with cast or walking boot. In cases of arthroscopy and microfracture of talus or tibia, or suture-endobutton fixation of the fibula, patients were instructed for partial weight-bearing (15 kg) for 6 weeks and with screw fixation only partial weightbearing (15 kg) for 2 weeks, followed by 4 weeks of full weight-bearing. According to our postoperative standard protocol syndesmosis screws were removed 6-8 weeks postoperative.

Results
In all 18 cases, a frank instability of the distal tibiofibular articulation was confirmed in intraoperative stress testing. Four patients had an arthroscopically confirmed disruption of the deltoid ligament and six patients a fracture of the medial malleolus. Furthermore, 11 patients had a radiologically approved additional posterior fracture of the distal tibia or tibial avulsion fracture of the posterior inferior tibiofibular ligament.
Traumatic lesions of the cartilage were found in 10 of 18 ankles (56%). The medial aspect of the talar dome was involved in eight cases, while tibial articulation was affected in 2 patients. A wide range of different (osteo-) chondral lesions was seen intraoperatively (Figs. 2 and 3) and classified as shown in Table 1. With exception of the patient with the grade I talar lesion, additional operative treatment was needed in nine cartilage lesions. Therefore, all nine patients were treated with arthroscopical debridement of ruptured and loose cartilage. In three talar and one tibial lesion additional bone marrow stimulation with microfracture of the subchondral bone was necessary.
Postoperative treatment was performed according to our standard protocol with partial weight-bearing for 6 weeks or partial weight-bearing for 2 weeks, followed by 4 weeks of full weight-bearing and screw removal after 6 weeks.
Twelve patients were available for a short-term followup. Mean time to follow-up was 15 months (range 3 to

Discussion
Treatment of MFC varies widely; traditional therapy consists of open or percutaneous techniques with restoration of the ankle mortise and syndesmosis screw fixation.
Kalyani [16] reported in a review, including 61 patients in 4 studies, of excellent results in 47.54%, good in 40.98%, fair in 4.92% and poor in 6.55% as well as an ankle arthrosis rate of 16% after an follow-up period from 25.3 months to 6.4 years. Furthermore, a high rate of associated cartilage lesions in common ankle fractures of up to 79.2% [10,11] and 100% in MFC [8] have been described. According to this data, a high rate of concomitant cartilage injuries is confirmed in our study. Therefore, ankle arthroscopy might be a favourable method to detect and subsequently treat associated injuries. In general, the incidence of complications in ankle arthroscopy is low. Imade [17] reported of one patient with compartment syndrome following ankle arthroscopy after MFC. In our own patient collective, as well as in the report of Yoshimura [8], were no complications as a result of ankle arthroscopy found.
Furthermore, the mechanism of injury was supposed to be a strong external rotation force with the foot in slight supination and in neutral or slight pronation in later stages [2]. Based on the fact that there was no damage to the posterior malleolus in their patient collective, Yoshimura [8] concluded that there is a strong possibility that the MFC could be a pronation external rotation type fracture according to the Lauge-Hansen classification. In four of our patients MFC occurred in a ski boot while skiing; Fritschy [18] also reported of Maisonneuve injuries in professional skiers with rigid ski boots, in which pronation or supination is theoretically impossible. Therefore, the mechanism of injury and potentially associated intra-articular damage have to be thought about. In all cases an apparent syndesmosis instability of at least 4 mm was seen Fig. 2 A variety of (osteo-)chondral lesions were found arthroscopically: cartilage hematoma (a) as well as instable talar (b) and tibial (c) cartilage injuries, which were debrided and subchondral bone microfractured Regarding limitations of this study, the small and heterogenous patient collective has to be disclosed. Furthermore, there was no control group, a short follow-up time and no long-time results available. On the other hand, the strength of this paper represents the largest number of study participants with MFC who were treated arthroscopically in current literature and all patients were treated by a national-board certified foot and ankle surgeon.

Conclusions
Ankle arthroscopy is helpful to detect and treat cartilage lesions of talus and tibia in MFC, as well as to guide fibular reduction. To avoid secondary complications, we do not recommend using endobutton fixation for MFC and early screw removal. Furthermore, the long-term results of this technique compared to conventional open surgery need to be evaluated in a larger patient cohort. Nonetheless, due to the high rate of chondral lesions, addressing these arthroscopically may contribute to better postoperative results.