Comparison of lateral approach versus anterolateral approach with Herbert screw fixation for isolated coronal shear fractures of humeral capitellum

Fractures of the humeral capitellum are rare injuries [1]. Due to the intraarticular and complex nature of these injuries and their rarity, it has been technically challenging to treat these injuries [2‐4]. Inadequately treated fractures may lead to a severe compromise in function owing to the restricted range of motion (ROM). Currently, open reduction and internal fixation with an aim to provide stable and congruent joint has been considered to be a standard treatment [5].

The choice of surgical approach is one of the main areas of interest in the surgical management of fractures. For coronal shear fractures of capitellum, namely capitellar fractures without involvement of posterior aspect, most reports have used the lateral approach of elbow joint [6‐16]. Though favorable outcomes have been reported, exposure range of the anterior aspect of the distal humerus is inadequate through this approach. Benefiting from excellent visualization and allowing access to easier perpendicular fracture screw fixation, the anterolateral approach of elbow joint has also been adopted to treat this type of fracture in several reports [17‐21]. However, this approach carries a risk of iatrogenic injury to the radial nerve.

So far, the optimal approach for the treatment of capitellar shear fractures remains inconclusive. In this study, we aimed to prospectively review and compare the early clinical and radiographic outcomes of this kind of fractures treated with open reduction and internal Herbert screw fixation through the lateral approach or the anterolateral approach. To the best of our knowledge, this is the first report of such a comparison.

The demographics and results of the patients were presented in Table 1. Fourteen patients were assigned to lateral approach group, and 12 patients in anterolateral approach group. No significant difference was detected in the distribution of the age, gender, injury mechanism, Dubberley fracture classification, and follow-up duration between the two groups.

All fractures healed well in their normal anatomic position as seen on radiographs. At the final follow-up, no evidence of avascular necrosis of the fragments was found. No patients had any subjective complaints of instability of the elbow. The average ROM in the affected elbows of lateral approach group and anterolateral approach group was 135° ± 8° and 133 ± 10° in flexion-extension respectively, with an average loss of motion of 9° and 11° respectively compared with the unaffected elbows. ROM in supination-pronation in the affected elbows of lateral approach group and anterolateral approach group averaged 168° ± 7° and 170° ± 6°, with an average loss of motion of 10° and 8° respectively compared with the unaffected elbows. No significant difference was found between the two groups with respect to the ROM in supination-pronation, ROM in pronation-supination, loss of flexion-extension motion, or loss of pronation-supination motion (p > 0.05). The average MEPI score was more than 90 for both groups. No significant difference was found with respect to MEPI score between the two groups (p > 0.05). All patients were satisfied with the operative outcome and returned to their previous activity levels. No evidence of avascular necrosis, posttraumatic osteoarthritis, or heterotrophic ossification was found.

The choice of surgical approaches is usually based on the fracture type and complexity, comfort of the orthopedic surgeon, and protection of the blood supply. For capitellar coronal fractures, the most commonly used approach is the lateral approach of elbow joint [6‐16]. This approach was characterized by anatomic safety and simplicity, and adequate exposure of the radiocapitellar compartment. However, the visualization of the trochlea and medial articular extension is limited. One surgical technique can be used to improve the exposure range. The elbow is flexed to facilitate placement of blunt Hohmann retractors deep to the brachialis and the anterior capsule and over the medial column. This can facilitate maximal exposure of the anterior aspect of distal humerus [7]. Even so, we found that the manipulation of fracture reduction and internal fixation was difficult for Dubberley type 3A fractures, because operating space for factures is confined. Inevitably, operation time would be prolonged. All the surgeries via this approach in this series obtained accurate reduction and rigid fixation. However, we think that a single lateral approach probably could not address all type 3A fractures, especially those factures with trochlea comminution. Dubberley et al. suggested that a supplemental medial-based exposure, flexor-pronator split, should be prepared to perform, if the medial aspect of the trochlea cannot be seen adequately or reduction cannot be confirmed from the lateral approach [2].

The anterolateral approach has also been used in several reports for these injuries to achieve satisfactory outcomes [17‐21]. In the current study, with respect to clinical outcomes as determined by postoperative ROM of elbow and MEPI Score, no statistical difference was observed between two surgical approaches. The average MEPI score was more than 90 for both groups, which corresponds to an excellent outcome. These results are consistent with several related studies, which showed that poor results were only obtained in capitellar fractures with posterior comminution [2, 8‐10]. Based on our experience, the anterolateral approach can expose the capitellum and trochlea widely by directly approaching the anterior aspect of the elbow. It makes the reduction of fracture fragments more easily and accurately. Furthermore, fixation screws can be placed more easily perpendicular to the fracture line from anterior to posterior. So the use of anterolateral approach can circumvent the disadvantages of the lateral approach, such as limited visualization of the fracture fragment and relative difficulty of putting the screws from anterior to posterior. This can explain that operation time via anterolateral approach was less in this series of patients. The disadvantage for anterolateral approach is that the dissection carries a risk of iatrogenic injury to the radial nerve. In this case series, one incomplete posterior interosseous nerve injury occur, which recovered soon without residual compromise. Furthermore, no severe never injury complications were reported in literatures for this approach. In our opinion, accurate understanding of the neurovascular anatomy of this approach is fundamental in avoiding iatrogenic injury. The incidence of radial nerve injury is very small with direct visualization and careful retraction. Hence, the anterolateral approach is a safe way to fix coronal shear fractures of capitellum.

Many types of internal fixation devices have been reported for reconstruction of capitellar fractures [22‐25]. In a sawbone model biomechanical testing, Bryan and Morrey type I fractures were fixed with K-wires, Herbert screws, AO screws, and fine-threaded wires. The results showed that reconstructed fractures with screws were significantly more stable [25]. Herbert screws fixation has become popular for coronal shear fractures of the capitellum and good clinical results have been published because the advantages offered by these screws include excellent compression at the fracture fragments, stable fixation, and nonprominence of the implant intraarticularly [26].

Based on our findings, both lateral approach and anterolateral approach with Herbert screw internal fixation are suitable for coronal shear fractures of capitellum with satisfactory early outcomes. Compared with the lateral approach, the anterolateral approach made the surgical procedure easier and time saving in current series. The anterolateral approach was characterized by sufficient visualization of the joint including the medial articular surface, ease of achieving anatomic reduction and perpendicular fixation with screws in anterior to posterior direction. When the medial aspect of the trochlea is involved for capitellar coronal fractures, the anterolateral lateral approach should be preferred.