Mason type III fracture of the radial head is defifined as a comminuted, displaced fracture involving the entire radial head.For Masson III radial head fractures, capitellectomy is often used in the early stages. Although a satisfactory range of motion of the elbow joint can be obtained in the early stage, the stability of the elbow joint is significantly decreased in the long-term. With increased knowledge of the applied anatomy and biomechanics of the elbow joint, the radial head is considered an important structure to maintain lateral stability of the elbow joint and transmit load. Excision can cause elbow varus deformity, radial displacement, unstable elbow joint and other complications. Due to the radial head’s contribution to elbow stability, in absence of other bony or ligamentous lesions both internal fixation and prosthesis can be good treatment in these kinds of fractures[12, 13].
However, a prosthesis is expensive, and prosthesis loosening, sinking, and prosthesis wear may occur in the long-term after surgery. It is necessary to consider the patient's age, elbow function requirements, and economic factors comprehensively before concluding if a prosthesis is the best treatment. When considering a prosthesis, the following points should be addressed: 1) the osteotomy plane must be accurately grasped. If it is too high, the implanted prosthesis will be tight. If it is too low, the implanted prosthesis will be unable to make contact with the capitellum and result in an unsatisfactory surgical effect; 2) selecting the appropriate radial head prosthesis. If the diameter of the radial head prosthesis does not match that of the upper radioulnar joint, it can lead to the cam effect and affect the rotation center of the elbow joint; 3) it is necessary to repair the anterior joint capsule, lateral collateral ligament, and extensor insertion. Checking the stability of the elbow joint with the varus and valgus tension during the operation, to ensure the dynamic and static stability of the elbow joint to the greatest extent, is very important.
The on-table reconstruction technique refers to the removal of all the fracture pieces of the radial head and precise reduction under direct vision on the operating table. As Masson III fractures involving the articular surface of the radial head are often more than three pieces, the in vivo space for reduction is narrow, and reduction is usually more difficult. In our study, the larger fracture fragments were removed out and reduced by screws,the small fracture fragments were temporarily fixed with multiple fine Kirschner wires. The radial head was then put back into the elbow joint cavity for miniplate fixation after complete external splicing. The literature reports that this technique does not increase the probability of ischemic necrosis of the radial head[14, 15]. In the past, it was considered that the reduction and fixation were difficult in patients with more than 3 pieces of fracture and the failure rate of internal fixation and the probability of nonunion were high. However, in recent years, with the clinical application of the on-table reconstruction technology for Masson III radial head fractures, open reduction and miniplate fixation can obtain satisfactory clinical efficacy[14, 15]. The miniplate with a low notch has good flexibility and elasticity. It is easy to shape during operation and can provide good stability. However, the disadvantages of on-table reconstruction combined with miniplate fixation are as follows: 1) patients with obvious bone defects are more likely to form fracture non-union at a later stage; 2) for multiple elbow injuries, it generally needs to be fixed for 2-4 weeks, and too long a braking time is not conducive to the early functional exercise of the elbow.
There are several limitations in this study, including its retrospective nature, the small sample size, and the short follow-up time. The medium and long-term efficacy and safety need to be further confirmed in future studies. A randomized prospective trial with a large sample size and long-term follow-up is required to make more definitive conclusions.