Great difficulty and more failures were the descriptions of a chronic Monteggia fracture-dislocation. A great advance has been witnessed recently, focusing on exploring the better surgery reduction outcome; however, the consensus has never been made about a perfect protocol procedure to achieve satisfactory results. Our surgical procedure is based on the hypothesis that the ulnar osteotomy plays the most crucial role in achieving stable radial head reduction; hence, we calculated a new reference of PUL for the first time using in Monteggia disease, focusing on providing valuable information for the clinical use.
The ligament reconstruction technique was changed a lot and controversial. Forearm fascia, the remnant annular ligament, biceps or triceps tendon, and palmaris longus tendon graft were reported for the annular ligament reconstruction[13–15], for which was recommended for the importance in stabilizing the radioulnar joint and the forearm rotation [16, 17]. However, Rahbek and cols[18] had reconstructed the ligament in 10 patients and compared with six patients not did it, having no difference in the final result. Soni et al.[19] also reported a good outcome without ligament reconstruction in any six patients. Delmont et al. also performed a multicenter study comparing the ulnar osteotomy with annular ligament reconstruction or without it, no significant difference in clinical, functional outcomes between groups was found. In our research, open reduction of the radial head with remnant annular ligament repositioning or without ligament repairing and reconstruction was performed to obtain the reduction. However, the maintenance of this reduction should be achieved by optical ulnar osteotomy and enough lengthening.
Several issues should be addressed about ulnar osteotomy. The first one is the position of the osteotomy. Center of rotation angulation (CORA) and proximal part of ulnar metaphysis were the most mentioned position for osteotomy. However, the nonunion or delayed union problem was more prominent at the CORA site[20, 21]. Ulnar malunion was also blamed for the difficult of the radial head reduction[20]. Moreover, a proximal osteotomy was recommended for having an unnoticeable posterior curvature and avoiding forearm rotation restriction because the whole interosseous membrane (IOM) remains constant[18]. The second issue is quantitative of ulnar elongation and posterior bending angle. From our data, the more lengthening, the more angulation was needed. Three patients failed the reduction having an insufficient lengthening or angulation. Then, we ameliorated the technique based on the value of PUL, we concluded that the lengthening of the ulnar to more than the normal PUL was warranted. An open wedge angle proportional to the elongation was also needed, which allows for a stable reduction of the radial head in flexion, extension, pronation, and supination. In this way, the outcomes turn out well. This kind of osteotomy not only leaves room for the radial head reduction but also tensions the IOM against forces that would lead to recurrent radial head dislocation[4, 22].
After osteotomy, different internal or external fixation was reported to fix the ulnar. David et al. [14] reported the K-wire to stabilize the osteotomy and had no complications in 6 patients. Rahbek et al.[18] also stated that rigid fixation or pin with less stability could stabilize the osteotomy. However, this construct only provides relative stability, which may be inadequate for the older patients, the proximal osteotomy site, and maintaining the angular correction. Recently, external fixation has been reported to be a safe and effective methods to treat this injury. Bor, Yuan, and Lu [23–25] all reported their experience using external fixation to capture the ulna osteotomy's optimal position to achieve the best possible reduction of the radial head. However, wearing huge external fixation for several months might leave psychological problems. Pin tract infection, neurovascular problems, malunion, and the delayed union should also be addressed for this construction. Nowadays, rigid fixation with plate is more accepted, allowing for a post-operative ROM, minimizing contracture[26]. We modified the technique by putting plate into the ulnar's lateral or medial side instead of the backside. First, it could diminish the stress applied to the plate without plate bending, which reduces the risk of plate breakage. Second, it is more aesthetic and comfortable for patients because the palpable pain or bump will vanish.
The IOM has been reported to play an important role in the longitudinal and transverse stability of the forearm[27]. The recommended osteotomy on the proximal side also maintains the IOM's stouter distal fibers, better translating ulnar correction to the intact radius [26]. Soubeyrand et al[27] describe this structure as the middle radioulnar joint, which is a fibrous joint, allowing pronosupination and ensuring forearm stability. From our research, the obvious difference of MID between pre-operation with the final follow-up of these successful cases also explained the functional effect of IOM. As for the challenging patients whose radial head unstable after the scar tissue is dissected and the elongation and angulation of ulnar are finished, we might increase supination slightly, and then, the radial head was reduced. This fact highlights the crucial role played by the IOM in forearm stability.
The present study had limitations. First, this is a retrospective study to evaluate PUL's value in the treatment of chronic Monteggia lesion, however, this is the first to bring up this reference; more randomized controlled trials or prospective studies are required for further validation. Second, all patients need longer follow-up to confirm if there are any delayed redislocation.
In conclusion, we emphasize the importance of the ulnar osteotomy to obtain and maintain reduction of the radiocapitellar joint in chronic Monteggia lesions by addressing both length and angular. Enough elongation to at least normal PUL and balanced angulation of the osteotomy is warranted to keep satisfactory outcomes. It is more aesthetic and safer to put the plate into the lateral or medial side of the ulnar. The functional effect of IOM cannot be neglected during the surgeries. Iliac crest autograft is recommended to avoid nonunion of ulnar osteotomy after lengthening.