The decision-making approach in complex tibial plateau fractures can be particularly controversial when PL and PM columns are involved [1, 4, 11, 12, 14, 16, 18, 19, 31]. In our opinion, the management of the PL column depends especially on the associated column(s) and the Main Deformity Direction (MDD), understood as a theoretical vector of global columns displacement or deformity [4]. Especially in two-column PM + PL and multi-columnar PM-MDD fractures, we believe that an optimized deep posteromedial interval approach could potentially offer a better direction to manage the deformity of the PL and PM columns in these cases [4]. In this sense, the MOL approach was designed to improve the access to the PL column through a deep posteromedial interval [4].

Several approaches, with different skin and fascia incisions and positions, have been previously described through the deep posteromedial interval between medial gastrocnemius and pes anserinus [1, 4, 8, 9, 34]. The classical posteromedial approach in the supine position uses a longitudinal skin incision 2 cm posterior to the posteromedial border of the tibia [7, 35]. This approach can be useful for simple metaphyseal PM column fractures. However, the knee flexion and the location of the incision can be a limitation when treating more complex PM column fractures [4, 9]. The Lobenhoffer approach uses a longitudinal straight incision slightly posterior, along the border of the medial gastrocnemius, performed in prone position with knee extension [8, 9]. This approach improves the management of PM column [9]. However, in our opinion, the medial location of the skin and fascia incision can limit access to the PL column. Krause et al. [11] in a cadaveric study, using the Lobenhoffer approach, refer to visibility of only fractions of the posterolateral central (PLC) segment, but a valid labelling of these regions was not consistently possible. The Luo approach (posterior reverse L-shaped approach) in prone position adds to the longitudinal incision of the Lobenhoffer approach, with a transverse incision from the centre of the popliteal fossa and develops a full thickness fasciocutaneous flap [1, 10]. Several authors agree that the Luo approach can improve access to the PM and PL column [1, 23]. Nevertheless, other authors referred limitations in the PL column exposure using the Luo approach [12, 13, 31, 32]. Orapiriyakul et al. [12], in a cadaveric study, considered a blinded area for the Luo approach when the fracture of the PL column is located more than 43.72% lateral to the lateral tibia spine. Additionally, the correct screw direction or even the capacity of placing the proximal screws of the posterior plate, when fixing the PL column, may be considered difficult using Lobenhoffer or Luo approaches [3, 12, 16]. Owing to these limitations, several authors recommend to associate specifically designed posterolateral approaches [20, 22, 25] to address the PL column even in two-column PM + PL fractures [11, 12].

In this cadaveric study using the MOL approach, we were able to obtain a successful and safe exposure of the PL and PM columns. The incision near to the posterior midline avoids the limitation for PL column access generated by the skin and fascia with the traditional Lobenhoffer approach [3] and avoids the extensive flap of the Luo approach [12, 16]. The oblique incision also optimizes access to the PL column at the proximal level, even potentially allowing perpendicular screw placement (Figs. 9 and 10), while maintaining a good exposure to the PM column.

Specifically designed posterolateral approaches through extended anterolateral (EAL), lateral or posterolateral incisions [3, 4, 20, 22,23,24,25,26,27,28] can be excellent options to address the PL column in certain situations, not discussed in this paper, such as one-column PL or two-column L + PL fractures [4]. However, in two-column PM + PL fractures or in multi-columnar PM-MDD fractures, the MOL approach can constitute a favourable option to manage the PM and PL columns. It can offer better control of the deformities (Fig. 7) without requiring additional posterolateral approaches [4]. These posterolateral approaches also have their own limitations and risks, including potential injury to the lateral collateral ligament, the common peroneal nerve, the lateral sural cutaneous nerve and especially the anterior tibial artery which represents the distal limit for exposure and plating in these approaches [13, 22, 29]. In this regard, the MOL approach offers the additional advantage to overcome the distal limitation imposed by the anterior tibial artery in posterolateral approaches. This allows for a complete exposure of the PL column, from the articular level to distal fragments, without limitations on the use of longer posterolateral plates (Figs. 6 and 10). In certain complex multi-columnar fractures, especially in PL-MDD fractures, both the MOL approach and the EAL approach can also serve as complementary options for PL column management [4].

Other authors have proposed direct posterior approaches between gastrocnemius muscles to address PL and PM columns [31,32,33]. These approaches require a more complex dissection and manipulation of the MSCN and popliteal neurovascular bundle. Motor branches of the tibial nerve can also be potentially damaged when separating the gastrocnemius muscles [36, 37]. Chouhan et al. [33], in their series of 22 patients, performing a midline gastrocnemius splitting approach (with a lazy-S shaped skin incision), reported two cases of sural nerve paresthesia. Berber et al. [31] described an approach with an inverted L-shaped skin incision similar to the Luo approach but with a transverse incision from lateral to medial, along the knee crease. The neurovascular structures were identified in the midline between gastrocnemius muscles, followed by retraction or tenotomy of the medial gastrocnemius muscle. In their series of 16 patients, they reported one patient with tibial nerve neuroapraxia, one case of partial sensory neuroapraxia and two cases of arthrofibrosis requiring manipulation [31]. Tenotomy of the medial gastrocnemius muscle is considered an option to improve PL access in posteromedial approaches [31, 38, 39]. However, several authors refer that this tenotomy should be avoided, if possible, owing to unnecessary risk of weakening the gastrocnemius-soleus muscle, late equinus deformity or knee stiffness [3, 12]. In the present study, no cadaveric specimens required medial gastrocnemius tenotomy.

Direct dissection of the popliteal neurovascular bundle is not required in the MOL approach (or in other deep posteromedial interval approaches). Normally, the elevation of the popliteus muscle protects the popliteal artery and the ATA, but anatomical variants should be considered [13]. Several studies reported that 0.8–6% of cases with a pattern where the ATA runs through the anterior surface of the popliteus muscle [40, 41]. In these infrequent situations, the artery could be at risk during the popliteus elevation if the dissection is not performed carefully. In the MOL approach, during the placement of the first Hohmann retractor, the ATA could also potentially be at risk at the level of the crossing, located at 35.7 ± 9.0 mm (range 17–50 mm) distal to the fibular head [29]. Therefore, the safest level for this retractor would be below 50 mm. However, even at the level of the foramen, the ATA can be partially protected during the placement of the retractor by the tibial origin of the tibialis posterior muscle and the location of the artery closer to the fibula (Fig. 4). The ATA runs between the two heads of the tibialis posterior muscle and continues through the interosseous foramen to enter the anterior compartment [42]. At the foramen, the ATA is located at a mean distance of 4.2 ± 0.5 mm from the lateral border of the tibia and 1.5 ± 0.4 mm from the medial border of the fibula [42]. Nevertheless, the mobility of the ATA is relatively poor at this level [32], so careful management of this retractor is essential to avoid vascular damaging.

The risk of damage to cutaneous nerves are part of iatrogenic complications in surgical approaches [43] and are often underdiagnosed [44]. In the Luo and traditional Lobenhoffer approaches, owing to a more medial incision, the saphenous nerve can potentially be damaged [3, 10, 44, 45]. In contrast, Van den Berg et al. [2] commented on the possibility of increasing the risk of damaging the sural structures by performing the incision more lateral. Berwin et al. [34] proposed a straight skin and fascia incision over the middle of medial gastrocnemius, without neurological complications in a series of six patients. In the proposed MOL approach, one of the keys is the anatomical rationale for the location and obliquity of the incision based on the anatomy of the medial sural cutaneous nerve (MSCN) and the cutaneous innervation of the posterior part of the knee [36, 37, 44,45,46,47,48]. The MSCN is the most medial structure of the sural nerve complex [