A hybrid technique combining intramedullary pinning with extramedullary plate fixation in unstable and comminuted radial head fractures following on-table reconstruction

Mason type III fractures refer to comminuted fractures involving the entire radial head displaced from the shaft [1]. The common surgical treatments for such complicated injuries, such as radial head resection (RHR), radial head arthroplasty (RHA) and open reduction and internal fixation (ORIF), have their merits and demerits, respectively. Since there is lack of long-term and large-volume studies in comminuted radial head fractures, the optimal treatment has not reached a consensus [2, 3]. Currently, it has been well recognized that the radial head is an important stabilizer of the forearm and elbow [4]. The emergence of specific radial head implants and innovative techniques have made ORIF preferable to preserve the integrity of the fractured radial head [5, 6].

On-table reconstruction technique is first described by Businger et al., which allows the radial head fragments fixed on the operation table with preliminary fixation using reduction clamps and 1 mm Kirschner wires [7]. This technique provides an optional treatment method and solves a critical challenge that ORIF is almost impossible to repair comminuted fractures with more fragments. Subsequent published series have proved the availability of this technique. Kiran et al. [8] have shown that following Ex situ reconstruction technique, six patients with Mason type-III radial head fractures have a satisfactory motion of elbow with the mean Broberg and Morrey score of 90 points. But non-union occurs in three patients and avascular necrosis in one patient in their study. Latterly, in another study by Everding et al. [9], the mean Mayo Elbow Performance score is 82 points and DASH score is 20 points with asymptomatic non-union occurred in one patient, and no signs of avascular necrosis are observed. Additionally, several on-table techniques using polylactide pins or surgical glue are reported with satisfactory to good surgical outcomes [10, 11]. Accordingly, this technique provides an optional solution for complicated radial head fractures. Nevertheless, since only a few studies have investigated small amounts of patients with conflicting complication rates, the treatment effects of on-table technique may be discrepant in different cases and its reliability needs to be evaluated cautiously in the practical surgical process.

In the present study, we found that some reconstructed radial heads after mini T-type plate fixation were prone to displace from the radial neck during surgery, characterized by a poor radiocapitellar contact and incongruity between the radial head and neck, and we named it unstable comminuted radial head fractures. In these cases, RHR may be considered as a remedial solution since internal implant has largely lost its effects. However, in the present study, a hybrid technique that combined intramedullary pinning with extramedullary plate fixation was manipulated to maintain the stability of fixation and restore the normal alignment in these unstable fractures, with RHR avoided. Additionally, we also retrospectively compared a series of patients surgically treated with RHR or our hybrid technique due to unstable comminuted radial head fractures, and to further assess the clinical and radiological outcomes of this technique. Therefore, the purpose of this article mainly was to ascertain whether the intramedullary pining fixation could be a remedial operation for unstable comminuted radial head fractures after on-table reconstruction technique.

Patients participated in the current analysis with an average follow-up of (38.6 ± 4.5) months for the experimental group and (32.0 ± 6.3) months for the control group, respectively. Figure 5 illustrated the typical cases.

At present, there is considerable conflicting evidence in the literature regarding the treatment of comminuted and displaced fractures of the radial head [2, 3, 6]. RHR as early treatment was once considered as a simple and useful approach. Clinical and radiological results from a retrospective review have documented good recovery in MEPS (from 79 to 100), DASH (from 4 to 15), and an acceptable elbow ROM (average 120°)following radial head resection [19]. Mebouinz et al. [20] have demonstrated radial head resection can restore elbow functionality at a rate of 81%. However, due to the damaged radiocapitellar contact, RHR has an increased risk of complications such as instability of valgus or posterolateral rotation, decreased strength, and degenerative changes in elbow and wrist [21]. Chen et al. [22] have reported that relative to RHR, RHA and ORIF can maintain higher Broberg-Morrey elbow joint scores, and they both show better efficacy in reducing pain, larger range of motion, and lower complication rates. Also similar to our study, seven patients with ORIF had a higher elbow functional scores compared with control group. The results were accordant with previous views that ORIF was a good option for Mason type III fractures with a low level of associated injury [23]. Nevertheless, no significant difference in the mean values of ROM of the injured elbow between two groups was found in the present study.

Biomechanical researches have proved the critical role of the radial head as a secondary stabilizer against both valgus and posterolateral instability of the elbow, especially in those cases with the medial collateral ligament or interosseous membrane of the forearm injury [4, 24]. Thus, being aware of the importance of the radial head for elbow function, RHA and ORIF are preferable in restoring normal radiocapitellar contact and anatomical structure. Several excellent short to midterm results have shown better operation outcomes in comminuted radial head fractures treated with RHA, which might be a preferred solution for such fractures but have inherent drawbacks, such as heterotopic ossification, joint stiffness, hardware loosening, and radiocapitellar osteoarthritis, particularly when the prosthesis overstuffs the radiocapitellar joint and further alters the biomechanics of the radial head [25‐27]. Consequently, ORIF might be the initial surgical solution to retain the integrity of the fractured radial head, so as to maintain normal articulation and bone stock. If ORIF fails early, it can still be converted into RHA.

A majority of previous studies have reported that comminuted radial head fractures with operative fixation have a high failure rate, nonunion, and osteonecrosis [28]. Moreover, severe Mason type-III radial head fractures are usually defined as “unsalvageable” or “unrepairable” type, which appears impossible to be treated with ORIF [29]. Nevertheless, the progress in implant technology and new fixation techniques have gradually overturned the established views. Particularly, on-table reconstruction technique has been reported and verified clinically. Several studies that exclusively focus on such technique for the complex radial head fractures have revealed satisfactory functional outcomes [7‐9]. This technique is not limited to the narrowing anatomical joint space, and allows the reconstructed radial head to replant with the use of plate, which should be worthy of supporting and popularizing. However, in view of the different characteristics of comminuted radial head fractures, difficult extent to fix fragments and a variety of internal implants, the stability of fixation in the reconstructed radial head tends to be discrepant and remains to be assessed in different cases.

Koslowsky et al. [30] have compared four different fixation techniques for the reconstruction of Mason type III fractures in the sawbones model, and find that displacement of the radial head from the neck often occur during plate fixation. Similarly, this issue was observed in the present study after on-table reconstruction of the radial head, leading to a poor radiocapitellar contact and incongruity between the radial head and neck. It is well known that treatment of radial head fractures mainly aims to maximize elbow movement and stability to maintain function [31]. Correct alignment of the radial neck to the reconstructed radial head is crucial for normal rotation in the proximal radioulnar joint. Therefore, only reconstruction of the radial head fails to meet the treatment criterion. Furthermore, many biomechanical studies have shown that the stability in the coronal and sagittal plane largely depends on the anatomical restoration of the radiocapitellar relationship [32].

We analyzed that the unstable displacement might be correlated to the insufficient axial support provided by plate fixation. Both unfirm anchoring force and weak supporting strength from proximal screws to the reconstructed radial head were critical factors. Primarily, the reconstructed radial head with Kirschner wires might block inserting of the proximal screws, and the plate must be placed at “safe-zone,” which mainly limited the amounts, location, and direction of the screws. Moreover, the shape of fracture fragments was not uniform in different cases, so that the expected effects of manipulating on-table reconstruction remained uncertainties. The power drill, Kirschner wires, and proximal screws all probably would break the fragments and made reduction and fixation more complicated. Additionally, differences in plate type and operator’s surgical experience could affect the definitive outcomes, which might be inconsistent with previously reported results. Conclusively, all above-mentioned factors might influence the anchoring force and supporting strength of screws, causing instability between the radial head and neck during plate fixation.

If plate fixation fails to offer reliable axial support, a hybrid technique combining with intramedullary pinning seems useful to compensate for that deficiency. The intramedullary pinning technique is always manipulated in children radial neck fractures, which allows minimally invasive and is easily performed, representing a favorable result with few complications [33]. Sandmann et al. [34] first report that intramedullary pinning not only suits to radial neck fractures in children but satisfactory in adults. A series of superior results have confirmed the feasibility of adult radial neck fractures fixed with intramedullary pinning. Gao et al. [35] has conceived a hypothesis that radial neck component could be stabilized by intramedullary pinning fixation following open reduction and plates or screws fixation in radial head fractures. This hybrid technique was manipulated and verified in our study, by which an additional axial support was obtained in the medullary cavity to prevent the displacement of reconstructed radial head from neck, and maintain restoration of radiocapitellar contact. Also, the use of elastic nail was modified in the present study. The proximal part of the elastic nail was bent, and formed three-point supporting consisting of the nail tip, bending point and nail bottom, which further enhance the axial support to avoid longitudinal displacement of the radial head.

Early failure in plate fixation is not infrequent, particularly in severe comminuted fractures. Ring et al. [28] have shown that 3 of 14 fractures (21.4%) with more than three articular fragments have failure in plate fixation within the first month. Therefore, if there is lack of stability and loss of normal alignment between the reconstructed radial head and neck during plate fixation, incorporating the use of intramedullary pining appears applicable. Moreover, stable fixation in fracture site allows patient to functional exercise early and promotes bone union. Kiran Kumar et al. [8] have reported that only 3 of the 6 patients treated with on-table reconstruction achieve fracture healing after a mean follow-up of 25 months, and one case occurs avascular necrosis of radial head. There is a strong possibility that these complications are attributed to the unstable plate fixation. Comparatively, in the present study, seven patients following additional intramedullary pinning fixation had obtained bone union without avascular necrosis of radial head observed during follow-up. This hybrid technique preserved the integrity of radial head and provided satisfactory elbow function compared with RHR, which was available for selection following unstable plate fixation.

Objectively speaking, there are still some risks and limitations to this technique. Firstly, after plate fixation, distal screws may block insertion of elastic nail. Actually, the axial direction of nail tip is designed to have an angle of approximately 30 degrees with nail shaft. During elastic nail insertion, we suggest that the direction in which nail tip point on the coronal plane should try to keep parallel with the distal screws, and in this way that nail tip can pass through distal screws with the minimum contact area. Additionally, the width of the proximal radial medullary cavity is about 6–7 mm, and the diameter of distal screws we used is 1.5 mm, thus there is a sufficient interspace between screws and medial cortical bone to allow 2.0 mm-sized elastic nail insertion. Secondly, inserting the elastic nail may penetrate the articular surface through the inter-fragmental gap, and cause failure in intramedullary fixation. In addition, the nail tip might potentially lift the fracture fragments, with the articular surface secondary displaced. Therefore, this technique needs the accumulation of operating experiences and learning curves, and the axial support provided by the elastic nail requires further biomechanical exploration. We suggest using the intraoperative fluoroscopy to control the inserting depth of nail, till the nail tip has advanced to the subchondral bone. Lastly, we note that the small number of cases, duration of follow-up and other potential factors could affect the evaluation of the two treatment methods. The influence of selection bias of limited cases may also have affected the evaluation of the results of experimental group in the present study. Hence it needs more quantitative analysis, multi-center studies and patient accumulation to assess the clinical effects of this technique.

On-table technique can offer an optional solution in the surgical treatment of comminuted radial head fractures. However, if there is unstable displacement from the reconstructed radial head to the neck during plate fixation, intramedullary pinning technique can be selected and applied as a remedial option. Indeed, this hybrid approach availably decrease the risks of failure in fixation and provide a good clinical result.