The Mason Classification for radial head fractures may be the most widely used [7]. Type 1 fractures are nondisplaced marginal fractures. Type 2 fractures are marginal fractures with displacement and type 3 fractures are comminuted fractures of the entire head [7]. In his original paper, Mason proposed nonoperative treatment for type 1 fractures and operative treatment for type 3 fractures [7]. Recent studies have validated that nonoperative treatment of isolated type 1 radial head fractures is reasonable, with 95 % of patients in one large series obtaining excellent or good outcomes [8]. In the setting of elbow instability with a type 1 fracture, nonoperative treatment may still be considered as long as there is a concentric reduction and a stable range of motion with no evidence of subluxation with flexion and extension. Type 3 fractures continue to be treated operatively with general consensus. The optimal treatment of type 2 fractures remains controversial. Some authors have reported excellent results after nonoperative treatment of certain isolated type 2 fractures [8] while others have reported very good results with operative treatment [9]. In the setting of complex dislocations , operative repair of type 2 fractures should be performed to maintain its role as a secondary stabilizer in the setting of an injured MCL.

In type 3 fractures, radial head arthroplasty offers better outcomes when it is made in the acute phase. Morrey [10] reported 92 % good outcome in the acute phase and 48 % good outcome when it is made in chronic phase. The worst result is seen in cases of delayed radial head arthroplasty. The use of allograft for reconstruction is unpredictable and in our opinion, should be avoided.

If the radial head is absent in the subacute setting due to a prior resection, it commonly needs to be replaced in order to help maintaining posterolateral and valgus stability in cases of chronic subluxation or instability. It is unclear which type of radial head arthroplasty is superior. However, the surgeon should not believe that radial head replacement alone solves the problem of an unstable elbow if the rest of anatomical structures involved are not addressed (Fig. 14.3).

In a concentrically reduced ulnohumeral joint , one can expect ligamentous healing. In acute ligamentous injury with associated complex instability, primary repair is often feasible. However, in delayed cases, the surgeon should prepare for ligament reconstruction. Repair and reconstruction techniques are described in previous chapters, and we encourage the reader to review them. Occasionally, especially when there has been an associated neurologic injury, one may find significant heterotopic ossification that needs to be removed and compels the surgeon to undergo a ligament reconstruction (Fig. 14.4).

Regan and Morrey [11] described three types of coronoid fracture. Type I fractures involve the tip of the coronoid, type II fractures involve more than the tip and less than 50 % of the coronoid, and type III fractures involve greater than 50 %. O’Driscoll et al. [4] described an alternative classification system involving three fracture types. Type 1 is a tip fracture, type 2 is an anteromedial facet fracture, and type 3 is a fracture through the base of the coronoid process. This classification stresses the importance of identifying fractures of the anteromedial facet of the coronoid caused by a varus force, leading to posteromedial rotatory instability.

Classical recommendations have been to fix all Regan-Morrey type II and III coronoid fractures as well as any type I fractures associated with instability. In type I fractures, many authors feel that there is not enough evidence of instability associated with this particular fracture type. Therefore, some authors do not feel there is enough evidence supporting the importance of their repair of this fracture type. The coronoid process has three significant soft tissue insertions : the anterior joint capsule, the brachialis muscle and the ulnar collateral ligament. Anatomic evidence demonstrates that the capsule usually attaches below the tip of the coronoid process and the anterior band of the MCL attaches more distal [12, 13]. Repair of fractures, depending on size, will also incorporate some or all of these soft tissue insertions playing an important role in elbow stability.

Josefsson [14] reported four cases in a series of patients that experienced recurrent instability after an initial elbow dislocation . All patients that re-dislocated had an associated fracture of coronoid that was not repaired at the time of initial treatment. Terada [15] demonstrated that repair of type I fractures could improve stability. Clinical evidence reported by Pugh [16] corroborates that finding, stating that type I injuries usually represent a capsular injury. Although in the acute setting fixation of small coronoid fragments may not be necessary, all these clinical findings stress the importance of addressing all possible stabilizers when dealing with persistent instability.

The coronoid fracture in the setting of elbow dislocations remains a significant cause of persistent instability, and it remains incompletely solved. It is still unknown what percentage of the coronoid is necessary to maintain elbow stability. However, it is rather clear that in type I fractures the issue is not the bone, but the anterior capsule.

In 2004, Schneeberger [17] demonstrated that elbows with a defect of 50 or 70 % of the coronoid, loss of the radial head, and intact ligaments could not be stabilized by radial head replacement alone; however, additional coronoid reconstruction was able to restore stability.

Because of its critical role in rendering stability, we try to fix all acute Type 3 fractures when possible and reconstruct it in those fractures that are not amenable to repair, such as those with extensive comminution. Type II fractures may be treated nonoperatively if the radiocapitellar joint can be reconstructed, the lateral ligament is repaired and the elbow is found to be stable through a full arc of motion. However, if the radial head is not amenable to fixation, a type II coronoid fracture may need to be fixed in addition to radial head replacement.

Repair alternatives include suture lasso technique, screw fixation (anterior to posterior or posterior to anterior) and plate fixation. Grant et al. [18] reported that the suture lasso technique was more stable than the other techniques intraoperatively, both before and after LUCL repair, and at final follow-up. Open reduction internal fixation (ORIF) was associated with a higher prevalence of implant failure, and suture anchors were associated with a higher prevalence of malunion and nonunion. Greater stability with fewer complications can be achieved with the use of the suture lasso technique for fixation of small coronoid fractures (Fig. 14.5). If the fracture is big enough, screw or plate fixation is probably the optimal technique (Fig. 14.6)

The most common scenario in the subluxed elbow presenting 3–6 weeks after the initial injury involves absence of a competent coronoid. In this situation there are several reconstruction options. Esser [19] in 1997 described reconstruction with radial head autograft. Moritomo [20] in 1998 published reconstruction with olecranon autograft; and Kohls-Gatzoulis [21] in 2004 and Chung [22] in 2007 reported good outcomes with iliac crest bone autograft.