Delayed treatment of missed Monteggia lesion poses several challenges. The probability of obtaining closed reduction of the radial head at that stage is almost negligible, and some form of surgery is required to restore normal anatomy [2
]. However, the reason for surgery is not always clear. Many children are asymptomatic and only present because of the deformity. The other issue is the duration of the ‘missed dislocation,’ which precludes a good result. Authors of the literature have reported successful reconstruction as late as 4 years after injury and, in rare cases, as late as 7 years [20
]. Left untreated, the children adapt well to the anomalous joint position in missed Monteggia fracture, but advancing age can compromise the result of surgery [24
]. There are few reports where surgery has been done in children over 10 years of age with good functional results [7
]. Kim et al. [7
] reported on three cases between 12 and 15 years of age with good success.
In this series, the oldest child was 12 years of age and the longest interval between injury and treatment was 18 months, and both children had an excellent to good outcome. The interval of missed dislocation in the older child was 10 months and probably did not result in significant dysplastic changes in the radio-capitellar joint.
The type of reconstruction varies and there is no clear consensus regarding the treatment of missed Monteggia fracture. Some authors have reported that an open reduction of the radial head is sufficient and an ulnar osteotomy is not required [25
]. Others have reiterated that ulna osteotomy is almost always necessary to restore radial head alignment [23
]. Although simple ulna osteotomies without fixation have been described [28
], the ulna angulation obtained after radial head reduction necessitates internal fixation to prevent re-displacement of the radial head [29
Also, the role of annular ligament reconstruction in maintaining radial head reduction has never been critically analysed. Some authors have advocated its use in every case that requires open surgery on the radio-capitellar joint. Reconstruction involves harvesting a fascial slip from the triceps aponeurosis or the forearm fascia and creating a loop around the radial neck. Speed and Boyd [22
] used a slip from the extensor aponeurosis, Bell Tawse [9
] used the central slip of the triceps fascia and Lloyd-Roberts and Bucknill [10
] modified this using the lateral slip attached distally. In theory, this fascial slip acts both as a dynamic and static stabiliser and prevents radial head subluxation.
Stoll et al. [2
] described eight cases of missed Monteggia fracture treated with annular ligament reconstruction, but also transfixed the radio-capitellar joint with Kirschner wire in two cases to enhance the stability.
We had five cases in which ligament reconstruction was required to maintain the radial head reduction and, in six cases, no ligament reconstruction was performed. The mean age, duration of dislocation and type of lesion were comparable in both of the groups. The decision to perform annular ligament reconstruction was based on the intra-operative stability of the radio-capitellar joint obtained after fixation of the ulna osteotomy. Often, slight distraction with posterior angulation of the ulna would enhance the anatomical alignment of the radio-capitellar joint. This presumably occurs due to the tautness in the interosseous membrane, which provides adequate stability to the radial head in some cases. The precise angulation and distraction would vary in each case, but future biomechanical studies on this subject should clarify the relationship between ulna angulation and enhanced radio-capitellar stability [30
Some authors have used gradual ulna distraction with an external fixator to effect radial head reduction without even opening the joint [14
]. These reports highlight the importance of ulna lengthening and, particularly, angulation in maintaining stability of the radial head. Hasler et al. [20
] reported on 15 cases of missed Monteggia fracture in which external fixation of the ulna osteotomy was combined with open reduction of the radio-capitellar joint [29
]. In their study, no patient underwent annular ligament reconstruction and no re-displacement of the radial head was reported at a mean follow up of 22 months.
Preliminary intra-operative external fixation may help determine precise ulna distraction and angulation before plate fixation. This could obviate the need for annular ligament reconstruction in some cases where radio-capitellar stability may be restored. Although we did not use this technique in any of our cases, external fixation has a potential role in the management of this complex injury.
Inoue and Shionoya [27
] stressed the importance of ulna angulation, as three of their six patients with simple osteotomy without angulation had persistent dislocation of the radial head. Three cases in this series required bone grafting; one case for non-union and the other two to enhance the stability of radial head reduction.
The child with missed lesion for 18 months required annular ligament reconstruction to stabilise the radial head and also ulna distraction–angulation osteotomy with bone grafting. One child in group B required angulation–distraction with bone grafting. The duration of missed dislocation was 11 months. Perhaps the key to adequate radial head reduction is the technique of ulna osteotomy and only a large multicentre series or meta-analysis can shine some more light on this intriguing problem.
Annular ligament reconstruction is not without complications. Gyr et al. [11
] reported on 15 children who underwent annular ligament reconstruction. All children had some limitation of forearm rotation and four cases had asymptomatic radial head re-subluxation. They emphasised that the ligament reconstruction can prevent the need for radial head excision in the future, as dysplastic changes occur commonly in untreated cases. After ligament reconstruction, the restriction of forearm rotation has been reported by several authors, and, also, nerve injury, myositis ossificans and re-displacement of the radial head are some of the documented complications [31
In this study, all children in group A and B had limitation of forearm rotation, pronation was more limited and this could, perhaps, be related to the position of forearm immobilisation in supination and the prolonged duration. However, the limitation of elbow motion did not affect the function of the child.
Residual radial head subluxation was seen in one case in our study. This could be due to laxity in the reconstructed ligament or due to poor initial repair. This has also been reported in other series and is asymptomatic and rarely affects function. Hui et al. [12
] reported residual subluxation in 2 of 15 cases and Rodgers et al. [31
] reported it in 2 of 7 cases in their series.
Seven of the children in this series did not need ligament reconstruction and this probably reflects the favourable results in this series. Eight children in total required ulna plating and, hence, needed bigger incisions. Although we did not look specifically for cosmesis, no child had complained about the scar.
In conclusion, this study stresses the importance of ulna alignment in restoring radial head stability and that annular ligament reconstruction is not always necessary. It would be prudent to quote a line from Campbell’s textbook of Orthopaedics, “regardless of how little or how much re-modelling has taken place, an osteotomy is usually necessary to lengthen the ulna and produce a stable radial head reduction.”