3.3 Distal humerus

1 Introduction

Distal humeral fractures (DHFs) in adults are complex and technically demanding injuries. In contrast to proximal humeral and distal radial fractures, operative fixation is indicated in most cases due to the impact of limited elbow function on activities of daily living. Many controversial and challenging issues include:

Difficult exposure (with or without olecranon osteotomy)
Comminution in the metaphyseal and/or epiphyseal region (with or without bone graft)
Fixation strategies
The role of primary total elbow arthroplasty

In order to achieve acceptable function, immobilization of the elbow should generally be avoided or at least limited to 2–3 weeks with intermittent mobilization.

2 Epidemiology and etiology

Distal humeral fractures account for 7–8% of all adult fractures in the western world [1]. Of more than 2,000 humeral fractures documented in the Swedish fracture registry between 2011 and 2013, only 8% were of the distal third, 79% of the proximal third, and 13% in the shaft. About 83% of humeral fractures affect patients older than 50 years [2]. Robinson et al [3] estimated an incidence of 5.7 cases per 100,000 people per year with a nearly equal male to female ratio. Of these, approximately 6% are isolated fractures of the capitulum humeri [4].

Looking at patient age reveals a bimodal peak: the first one represents 12–19-year-old men with fractures mostly due to high-energy trauma or athletic activities; the second peak is induced by women typically older than 80 years with osteoporotic bone who sustain the fracture after a ground level fall [5–7]. The latter group of patients demonstrated an increasing prevalence from 11 out of 100,000 in 1970 to 30 out of 100,000 in 1995 [8].

With the nondominant arm being affected in up to 89% of patients [7], the mechanism of injury in this population normally involves falling on the outstretched arm with a direct axial force transmitted to the capitulum humeri via the radial head [9]. The spontaneous reduction of a postero lateral elbow subluxation with shearing or compression force to the capitulum and/or the trochlea humeri represents a variant mechanism of injury [10].

3 Classification

In general, we distinguish between extra- and intercondylar DHF as well as capitellar and trochlear fractures. Several classifications of DHFs exist. Fractures are considered “distal” if they are located distal to the fossa olecrani:

In 2003, Ring et al [11] described five injury patterns based on radiographic and intraoperative findings.
The most commonly used classification is from the AO Foundation/Orthopaedic Trauma Association (AO/OTA), with letters from A to C for extraarticular, partial articular, and complete articular fractures. To describe the degree of comminution or give a further definition of the fracture location, the classification is further amended with numerals [5].
Distal coronal fractures (AO/OTA type B3 fractures) are specified and divided in subtypes by Bryan et al and modified by McKee ( Table 3.3-1 ) [12].

**Table 3.3-1** Bryan and Morrey classification of capitellar fractures modified by McKee **[12, 14]**.
Fracture type	Description
I (Hahn-Steinthal)	Coronal shear fracture resulting in osteochondral fragment extending up to the lateral ridge of the trochlea or minimally over it
II (Kocher-Lorenz)	Coronal shear fracture resulting in cartilaginous fragment with little or no subchondral bone attached
III	Fractures resulting in comminution of the capitellar fragment
IV (McKee modification) [13]	Coronal shear fracture of the capitulum and trochlea as a single fragment

4 Decision making

The combination of complex anatomy, fracture comminution, short distal fracture segment, and osteoporotic bone quality makes these fractures difficult to treat [10, 15]. In older patients, a stable fixation to allow for functional treatment is the most important goal. Smaller gaps or steps in the joint surface are of minor importance. An olecranon osteotomy should be avoided so as not to cause additional problems.

4.1 Approach

Numerous approaches to the elbow have been described. Functional outcome does not appear to depend on the approach used [16, 17]. The approaches can be divided into posterior, medial, and lateral approaches. From posterior, we may use an olecranon osteotomy, triceps-splitting, triceps-reflecting [18], and triceps-sparing approaches.

Our preferred approach is the triceps-sparing paratricipital posterior approach according to Alonso-Llames [19]. It allows the surgeon to address medial and lateral aspects of the distal humerus and may be complemented by an olecranon osteotomy if necessary. In older patients, there should always be an attempt to manage fractures without olecranon osteotomy ( Case 1: Fig 3.3-1 ). A tourniquet is not applied routinely.

**Fig 3.3-1a–c** Female patient with an AO/OTA type C3 distal humeral fracture. **a–b** A 3-D computed tomographic scan showing metaphyseal and epiphyseal comminution. **c–d** The 13-month follow-up x-ray showing fracture union.

AO/OTA C1 and C2 fractures are addressed via this approach without compromising the quality of reduction. In severely comminuted fractures, olecranon osteotomy may be necessary.

Due to the uncompromised extensor apparatus, immediate postoperative flexion/extension can be encouraged. Furthermore, this approach seems to be associated with fewer wound healing problems, shorter surgery time, and reduced blood loss compared to approaches involving an olecranon osteotomy ( Case 1: Fig 3.3-2 ) [20].

**Fig 3.3-2a–f** Triceps-sparing paratricipital posterior approach. A double curved skin incision is performed (a). Ulnar and radial full-thickness skin flaps are created and retracted to expose the triceps tendon (b). The ulnar nerve is identified and secured with a vessel loop (c). We do not routinely transpose the nerve at the end of surgery. The triceps tendon is mobilized and looped (d). Now, the radial and ulnar aspect of the elbow can be addressed alternatively by retracting the triceps tendon (**e–f**).

In case of coronal fracture types, leaving the anconeus muscle attached to the proximal ulna, an arthrotomy anterior to the collateral ligaments can be performed ( Case 2: Fig 3.3-3 ).

**Fig 3.3-3a–l** A 75-year-old woman with an elbow fracture dislocation and a fracture of the capitellum and trochlea. **a–e** X-rays images and 3-D computed tomographic scans showing a displaced capitellar and trochlear fracture with epiphyseal/metaphyseal fracture. f Clinical photograph showing the ruptured capsule with the capitellar fracture fragment on the radial side. g Clinical photograph of the ulnar incision. h Fixed ulnar column of the supracondylar fracture by ulnar plate. **i–j** Intraoperative image intensifier x-rays showing good fracture alignment. **k–l** Final follow-up x-rays showing fracture union.

CASE 1

Patient

A 79-year-old woman sustained an AO/OTA type C3 DHF after falling from standing height ( Fig 3.3-1a–b ).

Comorbidities

Osteoporosis
Hypertension
Insulin-dependent diabetes mellitus

Treatment and outcome

Surgery was performed in prone position without olecranon osteotomy. Using the bilateral paratricipital approach, the distal fracture fragments were fixed to each other using joysticks. Applying an inter fragmentary screw created one joint block, which was then fixed to the radial and ulnar column of the distal humerus using dorso-lateral and ulnar plates according to the 90° plating technique. Follow-up at 13 months showed fracture union with active range of motion of 0–15–120° ( Fig 3.3-1c ).

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3.3 Distal humerus