Re-dislocation after corrective osteotomy for chronic dislocation of the radial head in children

Quantitative Analysis for the Change in Lengths of the Radius and Ulna in Missed Bado Type I Monteggia Fracture

BACKGROUND

In missed Monteggia fracture (MMF) cases, ulnar angulation and lengthening by osteotomy are required to reduce the dislocated radial head. This study aimed to clarify the abnormal discrepancy in length between the radius and ulna in MMF. We tested the hypothesis that the increase in the abnormal discrepancy in length between the radius and ulna relates with the duration of radial head dislocation.

METHODS

In total, 24 patients with MMF were studied and classified into 2 groups, according to the duration of radial head dislocation, including the early group (n=9, within 3 y) and the long-standing group (n=15, older than 3 y). The lengths of the radius (Lr) and ulna (Lu) were measured. The difference in length between the ulna and radius (DL=Lu-Lr) was calculated on both the affected (DLaff) and normal (DLnor) sides. DLnor-DLaff, which represented an abnormal discrepancy in both bones, was analyzed for correlation with the duration of radial head dislocation and the age at initial injury.

RESULTS

The affected and normal sides had no differences in the Lr of both the groups and in the Lu of the early group. However, in the long-standing group, Lu was significantly smaller in the affected side than in the normal side (P=0.001). In the long-standing group, DLaff was significantly smaller, owing to decreased length of the ulna, than DLnor (P=0.003). The DLnor-DLaff was positively correlated with the duration of radial head dislocation and was negatively correlated with the age at injury.

CONCLUSIONS

In chronic MMF cases, the length of the ulna was shorter in the affected side than in the normal side. Therefore, ulnar lengthening is necessary to resolve this abnormal discrepancy and reduce the radial head. Because excessive ulnar lengthening has risks of postoperative complications, one of the surgical options is gradual ulnar lengthening or shortening osteotomy of the radius.

LEVEL OF EVIDENCE

Level III-Prognosis study.

Chronic Monteggia

PURPOSE OF REVIEW

The chronic Monteggia may lead to pain, mobility limitation, progressive valgus deformity, lateral elbow instability, late ulnar nerve paralysis, and degenerative changes. In this review, we discuss the current procedures in the literature focused on correcting chronic Monteggia to avoid these complications.

RECENT FINDINGS

Correction of the ulnar deformity with elongation and angulation of the ulna in the opposite direction of the dislocation of the radial head is the most important factor for the reduction and consequent preservation of the radial head. This correction reestablishes the relation of the ulna with the radius and increases the space of the interosseous membrane, providing greater stability after the reduction. The correction may be performed in the acute phase and stabilized with a properly molded plate and screws, or done progressively with an external fixator.

SUMMARY

The chronic Monteggia may occur along with undiagnosed lesions, such as plastic deformation of the ulna with radial head dislocation, or after an unsuccessfully treated acute Monteggia lesion. This condition may go unnoticed, thus requiring attention to the physical examination and imaging tests. Chronic Monteggia may be treated by ulnar osteotomy with progressive correction with an external fixator. However, the most common treatment is transverse proximal ulnar osteotomy, capsulotomy and removal interposed tissue, reduction of the radial head to the capitellum and temporary transcapitellar fixation, ulnar fixation with a straight plate molded to the ulnar deformity, which is usually deviated dorsally, removal of the transcapitellar Kirschner-wire, stability test, and, if necessary, annular ligament reconstruction.

The relationship between the morphological axis and the kinematic axis of the proximal radius

PURPOSE

Surgical procedures for impaired forearm rotation such as for chronic radial head dislocation remain controversial. We hypothesized that the morphological axis of the proximal radius is important for stable forearm rotation, and we aimed to clarify the relationship between the morphological axis and the kinematic axis of the proximal radius using four-dimensional computed tomography (4DCT).

METHODS

Ten healthy volunteers were enrolled. Four-dimensional CT of the dominant forearm during supination and pronation was obtained. The rotation axis of forearm rotation was calculated from all frames during supination and pronation. The principle axis of inertia, which represents the most stable rotation axis of a rigid body, was calculated for the proximal radius by extending its surface data incrementally by 1% from the proximal end. The angle between the kinematic rotation axis and the morphological rotation axis of each length was calculated.

RESULTS

The rotation axis of the forearm was positioned on the radial head 0.0 mm radial and 0.4 mm posterior to the center of the radial head proximally and 2.0 mm radial and 1.2 mm volar to the fovea of the ulnar head distally. The principle axis at 15.9% of the length of the proximal radius coincided with the forearm rotation axis (kinematic axis). Individual differences were very small (SD 1.4%).

CONCLUSION

Forearm rotation was based on the axis at 16% of the length of the proximal radius. This portion should be aligned in cases of severe morphological deformity of the radial head that cause "rattling motion" of the radial head after reduction procedures.

The minimum follow-up required for radial head arthroplasty: a meta-analysis

AIMS

The primary aim of this study was to define the standard minimum follow-up required to produce a reliable estimate of the rate of re-operation after radial head arthroplasty (RHA). The secondary objective was to define the leading reasons for re-operation.

MATERIALS AND METHODS

Four electronic databases, between January 2000 and March 2017 were searched. Articles reporting reasons for re-operation (Group I) and results (Group II) after RHA were included. In Group I, a meta-analysis was performed to obtain the standard minimum follow-up, the mean time to re-operation and the reason for failure. In Group II, the minimum follow-up for each study was compared with the standard minimum follow-up.

RESULTS

A total of 40 studies were analysed: three were Group I and included 80 implants and 37 were Group II and included 1192 implants. In Group I, the mean time to re-operation was 1.37 years (0 to 11.25), the standard minimum follow-up was 3.25 years; painful loosening was the main indication for re-operation. In Group II, 33 Group II articles (89.2%) reported a minimum follow-up of < 3.25 years.

CONCLUSION

The literature does not provide a reliable estimate of the rate of re-operation after RHA. The reproducibility of results would be improved by using a minimum follow-up of three years combined with a consensus of the definition of the reasons for failure after RHA. Cite this article: Bone Joint J 2017;99-B:1561-70.