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Varus posteromedial rotatory instability is a relatively rare elbow injury, that has been infrequently reported in published literature. We intended to evaluate the outcomes of surgical management of this rare injury with anteromedial coronoid fixation, and, in selected patients, lateral ulnar collateral ligament (LUCL) repair.
Methods
Between 2017 and 2020, we identified 12 patients with anteromedial coronoid fractures, and a varus posteromedial rotatory instability, who underwent surgery for fixation of the coronoid fracture, with or without LCL repair. All the included patients were either O'Driscoll subtype 2-2, or subtype 2–3. All the 12 patients were followed up for a minimum of 24 months, and their functional outcomes assessed using the Mayo Elbow Performance Score (MEPS).
Results
The mean MEPS recorded in our study was 92.08, and the mean range of elbow flexion achieved was 124.2°. The mean flexion contracture in our patients was 5.83°. Three of our twelve patients (25%) suffered from elbow stiffness even at final follow-up. The results were graded as Excellent in eight, Good in three, and Fair in one patient.
Conclusion
Coronoid fractures and LUCL disruptions associated with varus posteromedial rotatory instability can be reliably managed by employing a protocol that combines radiographic parameters, as well as intra-operative assessments of stability. While surgical intervention successfully restored stability, there is a learning curve to the management of these injuries and complications are not uncommon, particularly elbow stiffness. Hence, in addition to surgical fixation, emphasis should also be placed on intensive post-operative rehabilitation to improve outcomes.
This simple classification, proposed by Regan & Morrey, held its own for decades, before it was decided that there was a need to revisit the classification of these injuries. While being reproducible in varied settings, the simplicity of this classification is its biggest Achilles heel.
Recognizing these limitations, O'Driscoll et al. proposed a more descriptive classification for these injuries, which takes into consideration the integrity of the all-important anteromedial facet of the coronoid and size of the fracture fragment(s). This was soon followed by a description of varus posteromedial rotatory instability of the elbow.
This injury occurs secondary to axial loading of the elbow with a varus force, with the forearm in internal rotation. Ever since this description of anteromedial coronoid fractures and their role in elbow instability,
there has been a keen interest in the surgical management of these rare injuries, as inadequate surgical stabilization frequently leads to sub-optimal outcomes.
Also, when left unaddressed, these injuries lead to anterior subluxation of the trochlea into the coronoid process causing progressive damage to articular cartilage, predisposing to the development of early osteoarthritis.
Non operative management of these anteromedial coronoid fractures has been shown to be effective in only a select cohort of patients with minimal displacement, and no associated ligamentous injury.
Anteromedial coronoid fractures (hereafter referred to as AMCF), are also associated commonly with injury to the lateral collateral ligament complex, or uncommonly, to the medial collateral ligament complex.
While there is ample literature regarding anteromedial coronoid fractures, there is a relative dearth of published material on varus posteromedial rotatory instability. We therefore decided to document our experience in the diagnosis, planning and management of these rare injuries.
2. Materials and methods
After obtaining clearance from the Institutional Ethics Committee, this study was conducted as a retrospective study at the Government Hospital for Bone and Joint Surgery, Srinagar. Ours is a tertiary care centre, associated with the Government Medical College, Srinagar, in the Indian Union Territory of Jammu & Kashmir.
Looking up on our database between August 2017 and March 2020, a total of 12 patients diagnosed as O'Driscoll types 2, and 3 were included in this study. Patients were selected based on their radiographic, and computed tomography images depicting anteromedial fractures of the coronoid. As we decided to include those anteromedial coronoid fractures associated with ‘varus posteromedial rotatory instability’, patients with associated radial head fractures, terrible triad injuries, proximal olecranon fractures, or patients with Monteggia variants were excluded from the study.
Although radial head fractures have been encountered along with varus posteromedial rotatory instability, this association is very rare, and the presence of a radial head fracture should alert the surgeon to the presence of posterolateral rotatory instability, or a terrible triad injury.
In the pre-operative period, all the patients were subjected to plain orthogonal radiographs, and computed tomography. Emphasis was made to look for signs of ulnohumeral instability. These included the notorious ‘drop sign’,
narrowing of the medial ulnohumeral joint space, widening of the lateral ulnohumeral joint space, or any other irregularity of the ulnohumeral joint. Three-dimensional CT reconstruction was utilized in all cases for better depiction of fracture configuration. It also helped in the exclusion of other closely related elbow injuries. MRI was not performed in our cases, as our management algorithm was dependent on radiographic and computed tomographic measurements, and intra-operative stress testing.
Post-operatively, and on follow-up visits, all patients were assessed using plain radiographs.
3. Surgery
All surgeries were performed by the lead author under general anaesthesia, or a brachial plexus block. All patients were operated under tourniquet control. A medial Flexor-Pronator split approach (Hotchkiss) was utilized in most cases.
This approach splits the flexor pronator mass and elevates the pronator teres, flexor carpi radialis, and palmaris longus along with brachialis from the anterior elbow capsule. This approach gives good access to the anterior elbow capsule and the tip of the olecranon. Access to the base of the coronoid, however, is poor. For larger coronoid fractures, where access to the base is needed for medial plate fixation, the posteromedial Taylor and Scham approach was utilized.
In this, after isolating the Ulnar nerve, the entire flexor-pronator mass is elevated extraperiosteally from posterior to anterior to expose the base of the coronoid. Depending on the size of the coronoid fracture and comminution, internal fixation was achieved using plates or screws, or both. A protocol similar to the one employed by Rhyou and colleagues was used for decision making regarding fixation of the fragments, and regarding repair of the lateral ulnar collateral ligament LUCL (Fig. 1).
Following fixation of the anteromedial coronoid, stress testing was performed to rule out persistent varus instability. Only in those cases where there was persistent varus instability following coronoid fixation, was the LUCL repaired.
Fig. 1Management protocol for anteromedial coronoid fractures. LCL, lateral collateral ligament. Protocol is similar to the one employed by Rhyou et al.
In some cases the coronoid fracture was too comminuted (or too small) to allow stable fixation using hardware; so suture anchors were employed instead.
Valgus stress testing was also performed to rule out instability following completion of coronoid fixation, with or without LUCL repair. The medial collateral ligament (MCL) was not repaired in our study. Following fixation of the coronoid, the elbow was subject to varus stress testing under fluoroscopic guidance. A firm-end feeling, congruent ulnohumeral joint eliminated the need for an LUCL repair. A lateral approach was employed for fixation of the lateral ulnar collateral ligament, when needed.
Post-operatively, and on follow-up visits, all patients were assessed using plain radiographs. Pain, range of motion, and assessment of daily function was done using the Mayo Elbow Performance Score (MEPS).
Between 2017 and 2020, we reviewed a total of 12 patients in our study (ten men, and two women) with an anteromedial facet fracture of the coronoid process. Five were O'Driscoll type 2-2, and seven were O'Driscoll type 2–3. All of these patients were managed by surgery, details of which have been described in Table 1. The mean patient age was 31.08 years (21–48 years).
Table 1Patient, and fracture characteristics of the subjects included in the present study.
Of the five patients with O'Driscoll subtpe 2-2 injury, two fractures were fixed using buttress plates, two were fixed using suture anchors, and one fracture was fixed using a Herbert's screw. Three of these cases required repair of the LUCL, via a lateral approach. All the cases of LCL repair, were achieved using suture anchors. One such case is shown in Fig. 2, Fig. 3.
Fig. 2Pre-operative and post-operative x-rays of a patient (Subject 09). a,b: lateral, and anteroposterior views following injury. Avulsion of lateral collateral ligament (red arrow), lateral ulnohumeral joint space widening (yellow arrow). c,d: Post-operative x-rays showing fixation of coronoid, as well as lateral collateral ligament. Also seen here is restoration of lateral ulnohumeral congruity (white arrow, c).
There were seven patients diagnosed with an O'Driscoll subtype 2–3 injury. Although all of these were classified as PMRI, two of these were also associated with elbow dislocations at the time of injury. Six of these seven fractures were managed using buttress plates and screws, one case was fixed using a Herbert screw. Four of these cases required LUCL repair, and it was achieved in all cases using suture anchors. One such case is shown in Fig. 4, Fig. 5, Fig. 6, Fig. 7, Fig. 8.
Fig. 4Pre-operative AP (a), and Lateral (b) radiograph of anteromedial coronoid fracture associated with varus posteromedial rotatory instability.
Fig. 6Taylor and Scham approach for obtaining access to the base of the Coronoid. The Ulnar nerve has been isolated and retracted away from the field (arrow).
At the conclusion of the surgery, there was no instance where we encountered valgus instability. Hence, we did not explore the medial collateral ligament, and did not attempt repair in any case.
All the patients were followed up for a minimum of 24 months. The mean duration of follow-up was 29.7 months, with a standard deviation (±) of 6.4 months. The mean flexion of the elbow achieved in our series was 124.2° (±16.2°). The mean flexion contracture in our patients was 5.83° (±3.6°). The mean MEPS was 92.08 (±10.1). The results were graded as Excellent in eight, Good in three, and Fair in one patient. All our patients had resumed their pre-injury occupations at final follow-up.
Three of our patients (25%) suffered from elbow stiffness, even at final follow-up. Two of these cases were O'Driscoll type 2–3, where fixation was achieved using mini-fragment plates. Following fixation, elbow was deemed stable, and lateral repair was not performed. One case with stiffness had a type 2-2 fracture, and his fracture was stabilized using a screw. Intra-operative examination suggested instability on varus stress testing, and hence, lateral repair was also performed.
5. Discussion
The purpose of the present study was to review our centre's surgical experience in the management of Varus Posteromedial Rotatory Instability and associated anteromedial coronoid fractures (AMCF).
The management of these anteromedial coronoid fractures changed significantly after the proposal of a new classification system by O'Driscoll et al. Although appearing relatively benign and innocuous on plain x-ray films, these injuries are significant for their potential to disrupt normal elbow biomechanics, and predispose to secondary osteoarthritis of the joint.
described in detail their experiences regarding conservative management of coronoid fractures. While reporting excellent outcome in six patients, and good outcome in four patients, they acknowledged their exclusion of patients with ligamentous instabilities, and recommended surgical management for such cases. Moon et al.,
in their short series of three patients, described non-operative management of AMCF, with varus posteromedial rotatory instability. All their patients had O'Driscoll subtype II, minimally displaced fractures. They reported an excellent outcome in all three cases.
in their series of anteromedial fractures of the coronoid, reported signs of osteoarthritis at 26 months follow-up in six of their 18 subjects treated sub-optimally. They concluded that AMCFs associated with elbow dislocation/subluxation, or instability, are best managed by secure fixation of the coronoid facet. Similar studies have consistently demonstrated better functional outcomes following surgical fixation.
Good outcome using anatomically pre-formed buttress plates for anteromedial facet fractures of the coronoid—a retrospective study of twenty-four patients.
In their study, the authors neglected all coronoid fractures ≤ 5 mm. However, we chose fixation of smaller fragments as well, by means of suture anchors.
Among the handful of studies documenting PMRI, there have been some differences in the diagnosis, and subsequent handling of LUCL injuries as well. Rhyou et al.,
However, intra-operative clinical examination guided their final surgical management.
The decision to undertake LUCL repair was made only after addressing the coronoid fragment(s). Only in those cases where varus stress testing demonstrated instability, was the LUCL repair undertaken. We repaired the LUCL in seven (58%) out of our 12 patients. A systematic review on anteromedial coronoid fractures, and associated posteromedial rotatory instability concluded that general guidelines for repair of the LUCL are lacking, and that LUCL repair was performed in 70% of their studied patients. Consensus however, favours examination under anaesthesia with fluoroscopy to rule out instability before opting for or against LUCL repair.
Dynamic stress testing under anaesthesia significantly clarifies the extent of ligamentous injury and enables the surgeon to adopt a targeted approach to these injuries, rather than treat radiological findings alone. Also, some studies have reported that the role of MRI in diagnoses of LUCL injuries is itself controversial, as there are instances of altered signal intensities even within normal LUCL ligament in the absence of any injury.
Surgical repair of the medial collateral ligament (MCL) is a controversial step in the management of PMRI. It has been shown that only in the presence of both: an anteromedial coronoid fracture and an LCL injury, rupture of the MCL contributes to significant elbow instability.
Considering this, it has been found that MCL repair following fixation of the coronoid and LCL is not necessary, unless there is persistent residual instability after management of these two lesions. Also, the MCL has significant potential for spontaneous healing. Hence, even in the presence of an anteromedial coronoid fracture and rupture of the MCL, only the coronoid fracture needs fixation.
This was evident in our study as well, where we did not encounter any instance of elbow instability after addressing the coronoid; and the LUCL, where necessary.
The most commonly reported long term complication is secondary osteoarthritis.
Good outcome using anatomically pre-formed buttress plates for anteromedial facet fractures of the coronoid—a retrospective study of twenty-four patients.
Heterotopic ossification (HO) is another commonly reported complication in the studies evaluating AMCF. However, we did not encounter any patient developing heterotopic ossification during follow-up. One of the reasons for this could be that the studies reporting HO have included patients with terrible triad injuries: injuries that are well-known to be associated with a significant risk of developing HO.
These studies have included patients diagnosed with PMRI, as well as those diagnosed with other traumatic lesions of the elbow. Even though our study did not record any instance of HO, three of our patients still suffered from elbow stiffness at final follow-up. There were no clinical or radiographic signs of instability or osteoarthritis in these cases. Mean follow-up duration in these cases was 26.7 months and mean elbow range in these three patients was 78°. We did not perform any additional surgical procedure on any of these patients.
There are some limitations in our study. Firstly, the sample size is too small to draw definitive conclusions. Owing to the extremely rare nature of this injury, similarities drawn between our study and those that have been published are also confounded by the fact that many studies include anteromedial coronoid fractures associated with all traumatic elbow lesions, and not just varus posteromedial rotatory instability. Secondly, owing to the variations in injury characteristics, our included patients were managed by a variety of surgical methods. This does not allow for a valid comparison of outcome between the subjects. Thirdly, intra-operative assessment of instability is a very subjective method of determining the need for LUCL repair. However, for want of a better assessment tool, it is not entirely possible to eliminate this error, except for ‘standardizing’ within our own study by utilizing a single surgeon for all the cases.
6. Conclusions
Owing to the scarcity of clinical research regarding this injury, there has always been ambiguity regarding the optimal methods of fixation, and management of associated lesions. From our limited experience in handling these peculiar lesions, we conclude that the sole determinant of the mode of fixation is often the fragment size, and presence of varus elbow instability following coronoid fixation. The medial collateral ligament can safely be ignored if a stable elbow is achieved following fixation of the coronoid and the lateral ulnar collateral ligament. Patient, as well as the surgeon must be pro-active in timely institution of a physical therapy program to combat elbow stiffness. Further research is needed to streamline the protocols of managing varus posteromedial rotatory instability within the wider gamut of elbow disruptions.
Ethical approval
Institutional and Ethical approval has been obtained from Institutional Ethics Committee, Government Medical College, Srinagar vide Order no. 78/EC/17/2021.
Location
Government Hospital for Bone & Joint Surgery, Srinagar.
CRediT authorship contribution statement
Ansarul Haq Lone: Conceptualization, Methodology. Muhammad A. Hamid: Writing – original draft, Writing – review & editing. Zubair A. Geelani: Project administration. Yawar Naseer: Project administration.
Declaration of competing interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Good outcome using anatomically pre-formed buttress plates for anteromedial facet fractures of the coronoid—a retrospective study of twenty-four patients.
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