Isolated Fracture Dislocation of Medial Humeral Condyle Without Elbow Dislocation: Mechanism of an Unreported Injury

Abstract

Dislocations of elbow are often associated with fractures in proximal radius and/or ulna. In adults, fracture dislocations involving humeral condyle are exceptional and have been reported only in association with lateral humeral Condyle. Medial condyle Fracture dislocations have not been reported in adults. We present a curious case of isolated fracture dislocation of medial humeral condyle in an adult in a setting of supracondylar—intercondylar fracture of distal humerus in which elbow joint remains in position, while medial condylar fracture fragment gets dislodged from olecranon notch. A possible mechanism of injury is explained.

Introduction

Fracture dislocations of elbow in adults, have associated fractures usually in radius and/or ulna [1]. Fracture dislocation involving humeral condyle are common in paediatric population, but complex elbow dislocations with associated distal humeral fracture have been reported only exceptionally in adults [1]. Most common type of such dislocations is lateral condyle fracture dislocations [1]. Dislocations with supracondylar-intercondylar component are rare [2]. Medial condyle fracture dislocations in adults have never been reported.

We report a curious case of isolated anterior dislocation of the medial condyle of humerus in a case of supracondylar-intercondylar bi-column fracture of distal humerus, wherein lateral condyle fragment along with part of trochlea stays within its position in olecranon notch without any disruption of either the humeroulnar articulation or radio-capitellar articulation.

Case Report

A 20-year-old female reported to our hospital 6 days after slipping in a Sarson field (Mustard field), landing on left elbow and sliding for a few feet. Injury was closed with bruise on medial aspect. X rays (Fig. 1) and CT scan (Figs. 2 and 3) films are shown. Please note isolated anterior dislocation of Medial condyle fragment, with rest of articular surface still within olecranon notch. Also note minimally displaced, very low, lateral column fracture with intact radio-capitellar articulation. Fracture is classified as OTA 1.3 C1 with medial condyle dislocation. Closed reduction of dislocation had already been tried at secondary care centre and had been unsuccessful. No immediate attempt was made for any closed reduction at our centre. Patient had no other associated injury.

Fig. 1.

AP and lateral radiographs. Please note isolated dislocation of Medial Condylar Fragment. Supracondylar Component is not easily apparent

Fig. 2.

3D-CT Spots: views from anterior and medial aspect. Please note Mildly displaced Supracondylar Fracture line. Medial Condylar Fragment is dislocated anteriorly and locked against coronoid process. Please note empty medial part of olecranon notch

Fig. 3.

3D-CT Spots: views from Lateral and posterior aspect. Please note Intact radio-capitellar articulation in views from Lateral aspect and Intact Humero-ulnar articulation of Lateral condylar Fragment Supracondylar Fracture line. Note how lateral pillar of trochlea is with Lateral Condylar Fragment

After pre-anaesthetic work up, patient was taken up for surgery under general anaesthesia. A gentle closed reduction was attempted but it was difficult to get any hold on dislocated fragment which was locked against the coronoid process and reduction attempt was unsuccessful. No aggressive attempts at achieving closed reduction were made to avoid any aggravation of mildly displaced lateral column.

Surgery was done in lateral decubitus position with arm supported on a post with forearm hanging free to permit elbow flexion upto 120°–130°. A standard midline posterior incision was made. An olecranon chevron osteotomy was done under Image Intensifier control to place level of osteotomy at most distal part of bare area of olecranon notch to permit more direct access to the coronoid process, where dislocated fragment was locked.

The dislocated fragment was found rotated and carrying the attachments of common flexor origin and medial collateral ligament. Dislocated fragment could be unlocked from coronoid process in 100 to 110 degree of flexion. Moderate valgus force was applied to the elbow for relocation of dislocated fragment into the Olecranon Notch. The manoeuvre was not particularly difficult and reduction was achieved easily after de-rotation in hyperflexion.

Intercondylar fragments were converted into single fragment using two intercondylar wires passed from lateral to medial. Anatomical reduction of supracondylar component was then achieved and provisionally fixed with multiple K wires. Lateral column was stabilised with lateral column plate. Lateral column fracture was very low and only two 2.4 mm screws could be accommodated in capitellar area around already placed Intercondylar K wires.

Fine tuning of the reduction of medial fragment to stabilized lateral column was then done. Stable fixation of medial fragment to reconstructed lateral column was achieved with three Interfragmentary screws passed from lateral column to medial column (Fig. 4). Medial column plate was avoided to prevent stripping of attached muscles and ligaments from thin medial condylar fragment. One 2.4 mm Lag screw was finally inserted from medial to lateral above the attached tissues close to the beak of medial fragment to secure the fixation. The ulnar nerve transposition could be avoided because of absence of any major implants medially.

Fig. 4.

Post Op (Upper row) and Union X rays (Lower row): Please note that no major implant has been placed on medial column other than a 2.4 mm IF screw

Reattachment of the olecranon osteotomy was done with tension band wiring. The elbow joint was assessed and was found stable to varus or valgus stress as well as flexion and extension range. The surgical wounds were closed on a drain, sterile dressing was applied, and a posterior splint was applied. Drain was removed after 24 h of surgery.

Post-operative and follow up X-ray (complete follow up of 18 months is available) are shown in Fig. 4. Patient achieved an arc of motion from 5° to 160° flexion. Patient asked for removal of implant before her marriage, due in a few months, and was obliged. Range of motion is shown after removal of Implant (Fig. 5).

Fig. 5.

Range of Motion of Elbow at 18 months: 5° flexion to 160° flexion

Discussion

Terrible triad of Elbow is a recognised common injury pattern comprising of elbow dislocation associated with fractures in proximal radius and/or ulna [1]. However, complex Elbow dislocations with associated fractures in distal humerus in adults are much less common [1]. Results of open reduction and internal fixation are reported as good to excellent in such dislocations [1].

Compared to lateral condyle fracture dislocation; bi-column fracture dislocation is a rarity [2]. Only solitary case report in literature is of a 43-year-old female who sustained injury after falling from a height of 20 ft onto a concrete surface. Elbow dislocation was open. Whole of articular surface, separated from shaft fragment at Supracondylar fracture line, was dislodged out of Olecranon notch as intercondylar fracture line was un-displaced. Patient had associated fractures in acetabulum and bilateral radii. Fractures of the distal humerus was managed by ORIF. The dislocation was treated with closed reduction and splint stabilization in a manner identical to the approach used if the dislocation had presented as an isolated injury. Functional results were not reported.

Compared to reports in literature our case has few rare and unique features which can be enumerated as (1) Supracondylar fracture of humerus with dislocation of elbow in an adult (2) Dislocation is partial with isolated dislocation of medial condyle out of olecranon notch, while rest of joint remains congruent (3) Dislocation occurred in anterior direction. (4) Trauma causing the injury pattern was moderate with no other associated injuries or any open wound.

Furthermore, supracondylar—intercondylar distal humerus fracture line was very low. The Intercondylar fracture line was passing through medial third of Trochlea leaving radio-capitellar articulation completely undisturbed. The lateral 2/3 of the trochlea containing trochlear groove, lateral trochlear ridge along with capitellum formed the lateral articular fragment. This lateral articular fragment stayed within olecranon notch. Such a bi-column fracture with closed partial anterior elbow dislocation is so far an unrecognised entity.

From treatment point of view, except the reduction of anteriorly dislocated fragment which required unlocking from coronoid process in hyperflexion, de-rotation and relocation of the fragment into olecranon notch by opening medial joint line by valgus force; the treatment was by standard lateral column fixation using posterior midline trans-olecranon approach. Medial condylar fragment was much smaller and thinner than usual, and hence plate fixation of medial column was avoided. However, we could insert four Inter-fragmentary screws into the small fragment; three from lateral to medial and one 2.4 mm from medial to lateral and fixation was assessed to be adequate and stable. Avoidance of plate fixation helped us to leave all the muscle and ligament attachments to the small medial condylar fragment undisturbed.

Our case being first of its kind to be reported is off-course noteworthy, but the injury may have been caused by unusual mechanism as explained hereinafter. Elbow dislocations with distal humerus fracture described in literature result from violent trauma ranging from car accident to fall from heights on hard concrete surface. There was always high frequency of associated injuries in the same limb, other upper limb and other parts and dislocations may be compound. Our case was a slip in a Sarson (Mustard) field, where surface is neither hard nor there was any associated injury, nor was it open.

Historically mechanism of supracondylar—intercondylar fractures has been accepted to be an axial load on the elbow, with the olecranon acting as wedge, splitting the medial and lateral columns of the distal humerus. Mechanical studies have shown that bi-column fractures are produced with elbow flexed beyond 90°.

Milch [3] and Bentounsi [1] described mechanism of dislocations of elbow associated with isolated condylar fractures without supracondylar component. Milch emphasised importance of lateral wall of trochlea and explained how, when lateral wall of trochlea remains attached to the fracture fragment, fracture dislocation occurs; and simple fracture occurs when lateral wall of trochlea remains unseparated from humerus. Classically these dislocations are posterior with medial and lateral displacement depending upon the condyle fractured with fracture fragment displacing superiorly towards humerus.

In our case, the dislocated fragment does not have any part of lateral wall of trochlea. Intercondylar fracture line is far medial, leaving all of trochlear groove as well as some part of articular surface medial to it remaining attached to lateral wall of trochlea as part of lateral fragment. Milch [3] beautifully explained the stability provided by accurate fit of contiguous ridges and groves on articular surfaces of distal humerus and proximal radius and ulna. This may be the reason why humeroulnar and radio-capitellar joints did not dislocate in our case.

Most curious in our case is dislocation of medial condylar fragment with fragment displacing inferiorly towards coronoid process, and therefore, we believe that the axial force was not the reason for dislocation in our case. The inferior displacement has been recognised by Milch in fractures but not fracture dislocations. He explains that when force is applied to extended elbow “tension on ulnar collateral ligaments leads to an abduction avulsion fracture with downward displacement of medial condyle.” It is logical to conclude that avulsion force either by Ulnar collateral Ligament or attached Flexors was the underlying mechanism in displacement of the medial condyle fragment in our case.

In Milch description, the condylar fracture line extends obliquely, upwards and medially from joint surface; (1) from Trochlear Groove in Simple Fractures (2) Lateral to lateral wall of Trochlea in fracture dislocations. It is easy to understand why forearm bones will go with fracture fragment in either of these two situations, because accurate fit of contiguous ridges and groves on articular surfaces of distal humerus and proximal radius and ulna remains mostly Intact. In our case, because dislocated fracture fragment was separated medial to the contiguous fit of Trochlear groove and Olecranon-coronoid ridge, the forearm stayed with main articular Fragment in the elbow joint and did not dislocate.

It is interesting to note that intercondylar fracture line in our case was a clean vertical split and not oblique as anticipated in Milch description. Smaller than usual size of medial condylar fragment with verticality of fracture line along with location of the fracture line, medial to trochlear groove, may be the reason that avulsion force was able to pull out the fragment out of joint in our case unlike the scenarios described in Milch paper. Actively contracting flexor muscles may have provided the rotatory and tilting force necessary to ease out the medial condylar fragment out of sigmoid notch of olecranon. In context of active role of flexor muscles in the avulsion in this case, a parallel with epicondylar fracture avulsion seen with elbow dislocation in children and adolescents is difficult to miss [4].

One point of contradiction still remains. From foregoing description, it would imply that avulsion of medial condyle required extended position of elbow, while supracondylar fracture required flexed position of 90°. And our case had both components. From our understanding by detailed discussion with the patient, patient stumbled and fell in flexed position on the point of elbow and then the elbow got extended as the patient slid for a few feet on the slippery field.

Conclusion

A hitherto unrecognised closed, fracture- partial dislocation of elbow is described. various components of the injury viz partial isolated medial condyle elbow dislocation, Intra-articular fracture with fracture dislocation of humeral condyles, supracondylar fracture in combination with elbow dislocation are described in detail with reference to reported cases/case series. The possible mechanism of injury of this unrecognised entity is explained with reference to the existing understanding of mechanism of various components of complex injury.

Author contributions

All authors have contributed to study design, collection andinterpretation of data, literature search, preparation of manuscript and proof reading. Study design: RKM, RT, KM. Data collection: RKM, RT, KM. Data interpretation: RKM, RT, KM. Literature search: RKM, RT, KM. Manuscript writing: RKM, RT, KM. Proof reading: RKM, RT, KM.

Compliance with Ethical Standards

Conflict of Interest

On behalf of all authors, the corresponding author states that there is no conflict of interest.

Ethical Standard Statement

This article does not contain any studies with human or animal subjects performed by the any of the authors.

Consent to Publish

Informed consent was taken from all the individuals regarding publication of their identifying information.