Distal Humeral Fractures

Introduction

Distal humeral fractures are infrequent, when compared to other fractures and comprise approximately 1% to 2% of all adult fractures and 10% of humeral fractures. The population distribution of such fractures tends to be bimodal, with a peak in the 2nd and 3rd decades and a second peak in the 6th to 8th decades. The topic is variably covered in Chapter 44, Chapter 45, Chapter 46, Chapter 47, Chapter 48 .

Nonsurgical Management

Nonoperative options of soft sling or plaster cast (bag of bones) might be considered in cases in which reconstruction is not an option by virtue of patient or surgical factors. In debilitated patients, not considered to be surgical candidates, such management will compromise upper limb function and is considered unsatisfactory in approximately 40% of cases. As such, this is seldom considered as a viable option.

Fracture Fixation

A prerequisite for osteosynthesis is to develop a rigid fixation construct that synchronously allows stable fixation and early joint motion. However, there are three main fracture factors that adversely affect the ability to reconstruct the distal humeral fracture:

• 1

  Comminution: if the distal humeral articular surface is significantly comminuted ( Fig. 92.1A ), not only is it not possible to fix all the bony fragments, but the cartilage surface would also have undergone considerable injury, leading to a suboptimal bearing surface.

  

• 2

  Size of fracture fragment(s): it is straightforward to understand the issues with a large number of small bony fragments, with a significant number made up of small osteochondral fragments. Additionally a transcondylar or very low supracondylar fracture also poses the same problem of the ability to hold the fracture sufficiently rigid while allowing joint motion ( Fig. 92.1B and C ).

• 3

  Quality of bone: good quality young bone allows better fixation than does osteopenic/osteoporotic, older bone.

In a young population of average age 35 years, distal humeral articular surface fractures treated with internal fixation achieved good and sustainable results—an average flexion arc of 106 degrees, average forearm rotational arc of 165 degrees, and Mayo Elbow Performance Score (MEPS) of 91—although 40% required secondary procedures. A chronologically older group of patients with distal humeral fracture fixation can be successfully fixed: one study reported 75% good/excellent range of motion. Other studies of the older patient have not found the same favorable outcome. However, in the osteoporotic case, compromised fixation leads to one of two outcomes. First, if motion is attempted prior to bony union, the fixation may fail, leading to fracture nonunion. Helfet et al. demonstrated that despite good surgical technique and adequate internal fixation, 2% to 10% of such patients develop nonunions. Secondly, if early motion is sacrificed, a stiff joint is anticipated. Pajarinen and Bjorkenheim correlated immobilization greater than 3 weeks was an independent predictor of a poor functional score. Thereby, when the principle of rigid internal fixation with early joint mobilization cannot be adhered to, then joint replacement must be considered (Table 9.1).

Acute Total Elbow Arthroplasty

Given the preceding discussion, when the fracture is judged to be unpredictably unreconstructable, joint replacement is considered. There is a well-established body of literature of successful outcomes of joint replacement for acute fracture at the hip, shoulder, and less commonly at the knee. Total elbow replacement has been proven effective in numerous traumatic conditions: distal humeral nonunions, posttraumatic arthritis, and chronic fracture–dislocations.

The use of elbow replacement for acute fracture was described 20 years ago by Cobb and Morrey. Of 21 patients averaging 72 years with a mean surveillance of 3.5 years, there was only one reoperation, that being due to a traumatic fracture of the humeral stem (see Table 92.1 ). Based on the MEPS, there were 15 excellent outcomes and 5 good results. In 2004, the Mayo experience was extended to 43 patients, with a mean of 7 years' follow-up. Of note, 19 patients in this cohort had preexistent rheumatoid arthritis. The average flexion arc was 107 degrees, with a MEPS of 93/100. Five patients underwent revision: septic loosening ( n = 1), implant breakage following trauma ( n = 3), and aseptic loosening ( n = 1). Hence, although the revision rate increased from 5% at 3 years to 12% at 7 years, the outcomes were quite favorable.

Since then a growing body of literature clearly documents this as the treatment of choice of the comminuted fracture in the older patient ( Box 92.1 ). All except one of these reports employed a linked implant. Somewhat surprisingly, with a follow-up of 3.5 years the MEPS was 95 and the average arc of flexion was 98 degrees. No dislocations were reported. The most recent study provides insight into the longer term function of linked elbow arthroplasty. An impressive 89.5% of Coonrad-Morrey implants survived at a 10-year follow-up, with three patients requiring a revision implantation due to aseptic loosening, bushing failure, and infection. The reported complications after total elbow arthroplasty (TEA) for acute fracture are summarized in Box 92.2 .