Introduction

A non-united fracture of the distal humerus threatens the function of the entire upper limb. The involved elbow joint may be stiff, or grossly unstable, painful and associated with peripheral nerve dysfunction.¹ The non-union will compromise function of either the ipsilateral shoulder, hand, or both.

While fractures of the distal humerus are uncommon (2–6% of all fractures),^2,3 the unique regional anatomy, with the articular surfaces supported by limited bone yet subject to substantial reactive joint forces in normal daily activities, presents significant impediments to successful surgical fixation and functional outcome.

In this chapter we will present a comprehensive approach to the assessment, classifications, surgical management and outcomes of the treatment of those fractures of the distal humerus that fail to heal.

Background/aetiology

As our patients live longer, the incidence of upper extremity fractures including those involving the distal humerus is increasing. In addition, what we are seeing are more complex fractures occurring at or distal to the olecranon sulcus and associated with osteoporotic bone. These factors are providing the surgeon with an increasing challenge to achieve stable internal fixation that facilitates bone healing without complication. It is also leading to more interest in the use of total elbow arthroplasty as a primary form of fracture treatment.⁴ Closed or open distal humeral fractures are also seen in younger patients associated with higher-energy injuries. In each of these situations failure of bone healing has become a well-recognized adverse sequela.⁵ Additional risk factors contributing to non-union include obesity, alcoholism and patient unreliability, as well as advanced osteoporosis.⁶

Presentation, investigation and treatment options

A patient with a non-united distal humeral fracture will present with a dysfunctional upper limb. Pain at the non-union site, lack of elbow mobility, instability, distal hand compromise due to postsurgical swelling or peripheral nerve dysfunction, together with loose or prominent prior internal fixation devices, are all reasons for the patient to seek medical attention.

Clinical evaluation includes a careful and thorough history of the original injury, surgical treatment, and any medical or postsurgical complications. The patient’s overall medical health, such as diabetes, tobacco usage or treatment for osteoporosis, represents important potential risk factors. It is also paramount to determine the patient’s pre-injury functional status, limb dominance, extent of independence and social support.

The patient’s physical examination involves a careful assessment of the entire upper limb. The mobility of the adjacent joints including the ipsilateral shoulder, forearm, wrist and hand may be compromised from prolonged immobilization, postsurgical swelling or peripheral nerve injury or compression. The latter is particularly relevant as ulnar nerve compromise is now well recognized as a sequela of elbow trauma and surgical reconstruction and may be the source of pain as well as motor and sensory dysfunction in the hand.¹

Examination of the affected elbow must document the location and extent of previous surgical incisions, the adequacy and compliance of the soft tissue envelope, and joint mobility and/or instability. A grossly unstable or flail non-union will prevent the patient from effectively lifting the forearm against gravity (Fig. 20.1).

Figure 20.1 An unstable flail supracondylar nonunion. (A) In neutral. (B) Inability to lift the arm due to the instability.

Owing to the disturbed local anatomy at the non-union site, standard radiographs of the elbow may not adequately define the morphology of the nonunion. While evaluation of the original fracture and/or postoperative radiographs will be helpful, these are not always available. The distal articular fragment(s) of the non-union may be flexed due to capsular contracture and appear on the radiographs to be anatomically smaller than in reality.⁷ In these situations, or when non-unions occur within the articular surfaces, 3-D CT imaging may be extremely useful.

Careful assessment of the patient’s disability, associated risk factors, pre-injury functional status, and type and location of the non-union will allow the surgeon to develop an individualized treatment plan best suited to the patient’s needs and surgeon’s confidence and experience.

Treatment options will include a hinged functional brace for patients too infirm for surgery or who do not wish to undergo an additional surgical procedure; realignment with internal fixation and capsular release, or total elbow arthroplasty.¹

Surgical techniques and rehabilitation

The tactics of surgical treatment of a distal humerus non-union will depend upon the location and morphology of the non-union. Non-unions may be classified as supracondylar, intra-articular, or combined extra- and intra-articular (Table 20.1).⁷

Table 20.1 Classification of distal humeral non-unions based upon anatomical location

Non-union at the supracondylar level

Patient positioning, either lateral decubitus or prone, is dependent upon the surgeon’s preference but it is important to be able to flex the elbow to more than 120° in order to facilitate both surgical exposure and radiographic control. The iliac crest is prepared in the event that autogenous bone graft is required.

We prefer using a sterile tourniquet, although some might avoid this owing to the potential length of the reconstructive procedure. A straight dorsal surgical incision provides extensile exposure; however, prior incisions must be considered and included if possible (Fig. 20.2 (video)).

Figure 20.2 A 57-year-old executive with 18-month history of a painful non-union. (A) Radiograph of the supracondylar non-union with broken plates. (B) Video. (C) Functional outcome.

The ulnar nerve must be carefully mobilized, preferably for at least 6 cm proximal and distal to the cubital tunnel. The nerve is commonly surrounded by fibrosis that will limit its normal excursion following elbow mobilization, unless sufficiently mobilized and placed into the surrounding soft tissues (Fig. 20.3).

Figure 20.3 Step-by-step surgical fixation of a supracondylar level non-union. (A) Extensile exposure and mobilization of the ulnar nerve. (B) Following olecranon osteotomy the distal fragment can be mobilized. (C) The anterior capsule and synovial non-union are debrided through the non-union site. (D) The capsule is elevated off the distal aspect of the humerus shaft. (E) The distal end of the humerus shaft is contoured into a ‘V’. (F) Provisional fixation is done with smooth K-wires. (G) Stable impaction of the two fragments. (H) The lateral implant is applied first. (I) Close-up view of the impacted two fragments secured with two plates. (J) Bone graft placed around the impaction site. (K) Anteroposterior (AP) and lateral X-rays at 1 year.

A non-union at the supracondylar level can be effectively exposed through a triceps split, by exposure on either side of the triceps, or through an olecranon osteotomy. Whatever the chosen approach, elevation of the olecranon from the distal humeral articular surface must be done with extreme caution to avoid avulsion of articular cartilage that has become adherent due to lack of movement at the joint surfaces. Unless a total elbow arthroplasty is to be considered, we prefer exposure through an olecranon osteotomy created with a chevron cut with the apex pointing distally.

Once the non-union site is exposed, the posterior elbow capsule must be completely excised to permit mobilization of the distal articular fragment as well as the ulnotrochlear joint. The anterior capsule is readily accessed through the non-union site and excision will permit full exposure of the fracture fragments. The synovial membrane must also be excised to facilitate a more vascular environment.

The distorted anatomy will inhibit correct alignment of the fracture and, to improve this situation, the fracture ends should be carefully debrided. More stable impaction of the two fragments can be achieved by creating a trough in the distal fragment into which the contoured distal end of the humerus can be impacted. Provisional fixation with large, smooth K-wires placed through the medial and lateral aspects of the distal joint will not impede the placement of the definitive plate and screws.

The techniques of plate fixation will vary considerably based on the size of the distal fragment, the extent of the underlying osteoporosis, as well as the type and availability of implants. Although anatomically shaped implants have been developed for the distal humerus, the often-distorted anatomy that occurs with non-unions will frequently require contouring of standard plates. A third plate has proven to be useful in cases where limited bone exists in the distal fragment particularly if it is only possible to achieve one screw purchase per plate.⁸ Given that there is often incomplete bony contact, cancellous iliac crest graft should be used to fill in areas of bony defect (Fig. 20.4).

Figure 20.4 A very distal non-union in a 38-year-old male with gross instability. (A) AP X-ray of the non-union. (B) AP X-ray following stable fixation with three plates. (C) Lateral X-ray post surgery. (D, E) Functional outcome.

Combined intra- and extra-articular non-unions

The operative technique of reconstruction of a non-union, both within the articular surfaces as well as more proximally, is extremely complex. Preoperative planning is essential to determine whether or not such surgery should be considered. If surgical treatment is offered to the patient, the extensile exposure, capsular release, and articular and bony realignment are similar to that already described for supracondylar non-unions. With primarily lateral-sided problems, however, an extensile lateral approach can be used. By elevating both the brachioradialis and the long radial wrist extensor anteriorly and the lateral triceps posteriorly, the elbow can be ‘hinged’ open, exposing the anterior articular surface (Fig. 20.5). Fixation again requires plate contouring and, depending on the fracture configuration, a third plate may once more be necessary.

Figure 20.5 An intra-articular non-union of the lateral column. (A) AP X-ray of the nonunion. (B) Intraoperative view of the nonunion. (C, D) Lateral and AP X-rays of the healed non-union. (E, F) Functional outcome.

It is remarkable that the risk of avascular necrosis of the mobilized and realigned articular fragments is rare.

Outcome and literature review

Operative fixation of supracondylar distal humeral non-unions have variable functional results. In one of the largest publications, with a total of 52 patients, Helfet and Rosen treated 27 non-unions at the supracondylar level. Union was achieved in all 27, though complications were found in eight patients: four with postoperative ulnar nerve neuropathy, two with radial nerve neuropathy, two with deep infection and one with a compartment syndrome.³ In the senior author’s experience of 39 non-unions at the supracondylar level, all but four united after the index procedure, with only one patient requiring a second operation, following which union was successful.⁷ A subgroup of 15 patients with very unstable non-unions at the supracondylar level were reviewed by Ring et al.¹⁵ Of these, 12 of the non-unions united. Three failed to heal and were converted to total elbow arthroplasty. In the 12 that achieved union, the average arc of ulnohumeral motion was 95°, with an excellent Mayo Elbow Performance Index in two, good in nine and fair in one. When comparing these very unstable supracondylar-level non-unions with those with retained hardware or fibrous non-unions, it was evident that these are a more complex subgroup to treat.

Patients in whom non-unions extended into the ulnotrochlear joint fared less well despite gaining successful union. Increasing experience with these more complex non-unions led McKee to retrospectively review a combination of his own patients and those of the senior author.¹⁶ Seven of 13 patients reviewed had a malaligned intra-articular non-union. The mean age of the entire group was 39.7 years, with an average preoperative arc of motion of 43°. Nine patients had preoperative ulnar neuropathy. The elbow reconstructions were performed an average of 13.4 months following the original injury. At a mean follow-up of 25 months, union was achieved in all patients, with an average postoperative arc of motion of 97° and with a Mayo Elbow Performance Index that was excellent in two, good in eight and fair in three.

Use of vascularized fibular grafts¹⁷ has resulted in successful outcomes in two of the senior author’s patients where the original problem included complex wounds leading to infection and segmental bone loss. This technique has also had a successful outcome in four of five patients in the reported experience of Beredjiklian et al.¹⁸

The senior author has reported three cases of intra-articular non-union.¹⁹ One involved the anterior capitellum, one the capitellum and trochlea and one the posterior trochlea. These were originally treated with internal fixation. The preoperative arc of elbow flexion was 80°, 35° and 25°, respectively. All three non-unions healed, with an average follow-up of 34 months. The capitellar non-union showed partial avascular necrosis on follow-up X-rays. All patients obtained elbow flexion of 130° with an average flexion contracture of 27°. The mean Mayo Elbow Performance Index was 85 points.

The senior author reported on five patients with infected intra-articular non-unions over a 4-year period. In this series, four of the five patients achieved union of the fracture with the Ilizarov external fixator, although secondary cancellous bone grafting was required at the supracondylar level. These patients obtained a functional range of motion.²⁰ Similarly, in a series of six patients by Brinker et al,²¹ five patients achieved union with the Ilizarov external fixator. In both series the operative approach involved removal of the hardware, release of the ulnar nerve, debridement, autogenous bone grafting and application of the external fixator.

It has been widely thought that adult patients presenting with advanced ulnar nerve lesions with intrinsic muscle wasting had a poor prognosis of recovery after operative neurolysis. However, in a study of 20 consecutive patients treated following primary failure of fracture fixation and with an associated ulnar nerve lesion, a high rate of patient satisfaction was found as well as improved ulnar nerve sensory and motor function.²²

Experience with linked semi-constrained total elbow arthroplasty for patients who are not amenable to internal fixation has been reported in a series by Cil et al.²³ Ninety-one patients underwent total elbow arthroplasty for distal humeral non-union, with a mean follow-up of 6.5 years. Sixty-seven patients had no or mild pain, whereas 79 had moderate or severe pain preoperatively. Seventy-seven patients rated the outcome as better or much better. Twenty patients had fair or poor Mayo Elbow Performance Scores. Implant failure risk was increased by the following factors: patient age less then 65 years, two or more prior surgeries and a history of infection. In a review of 19 patients, 14 of whom had complex distal humeral non-unions associated with an unstable or flail elbow, Ramsey et al¹⁰ found functional motion in all of the patients with total elbow arthroplasty. The average arc of flexion ranged from 25° to 128°. The patients had little or no pain, although four complications were recorded.

The use of total elbow arthroplasty as a salvage procedure is also supported by the work of Friggie et al.²⁴

Complications of treatment

Following revision surgery for distal humeral non-unions, elbow contracture, ulnar nerve dysfunction and pain associated with the implant are all potential complications.¹⁵ Elbow contracture release should be offered to patients with an ulnohumeral arc of motion of ≤80°. Ulnar nerve neuropathy may be transient but when it is not consideration should be given to obtaining electrical studies and re-exploring the nerve to be sure it is fully released and transposed.

Conclusions/personal view

A number of factors are important when attempting to restore union and achieve a functional elbow for a patient with a distal humeral non-union. A careful preoperative clinical assessment is essential and appropriate radiological investigation, including CT, should be requested. At operation an extensile exposure is required and the ulnar nerve must be carefully mobilized. The contracture of the capsule should be excised and any intra- and extra-articular adhesions released. Revision fixation of the fracture with autologous bone grafting is then performed in order to achieve stable fixation.

Using this approach the majority of distal humeral non-unions can be successfully treated and bony union achieved. Where this is not possible, total elbow arthroplasty is an alternative and can be expected to give satisfactory results.