Non-Unions About the Elbow

The Problem

Modern techniques of fracture fixation and our understanding of fracture biology have improved the outcomes of all fracture surgeries, including those about the elbow. Nonetheless, failure of fracture healing, also referred to as non-union, may occur in this anatomic location along with the burden of devastating functional sequelae. The elbow is an intricately constructed joint, relying on well-defined articulations between the distal humerus, olecranon, coronoid process, and radial head for stability. A non-union developing at any one of these sites severely compromises the joint’s ability to maintain stability through full range of motion (ROM) and may significantly inhibit the patient.

The main complaints associated with non-union about the elbow include pain, instability, and loss of function. This trio of symptoms must be recognized and addressed in the post-traumatic patient in order to restore joint function and patient functionality. Risk factors for non-union about the elbow fall into four general categories: excessive motion, avascularity, gapping or bone loss, and infection. Most patients are pushed for early motion after initial surgery to prevent elbow stiffness; in the presence of an unstable construct this standard rehabilitation protocol may lead to non-union.

Prior to current open reduction internal fixation (ORIF) techniques, most non-unions occurred in the setting of low-energy injuries that were treated non-operatively. These non-unions were usually hypertrophic and occurred as a result of sub-optimal methods of approximation. Currently, an increasing number of elbow non-unions are atrophic and may be complicated by infection, bone loss, soft tissue deficit, and nerve damage. The complex reconstructive processes used to treat these “more advanced” non-unions come at the risk of further complications: motor and sensory deficit, continued non-union, and pain syndromes such as reflex sympathetic dystrophy.

There is a non-union incidence of up to 5% in distal humerus fractures. Distal humerus non-unions are twice as common in females, most especially the elderly. The incidence of non-union is between 1-5% in olecranon fractures; significant because non-union is a known and accepted complication of olecranon osteotomy for exposure in distal humerus fracture fixation. Non-union of the radial head and neck are uncommon, likely because the radial head is frequently resected in highly comminuted fractures. When non-union does arise at this site it is often asymptomatic and expectant management is the norm.

Clinical Presentation

When evaluating a patient with non-union about the elbow, details regarding the initial injury should be carefully sought after. The history and physical exam should make concerted effort to understand all details of the initial injury mechanism, fracture characteristics, and any subsequent treatment attempts. The patient may also present with general risk factors for non-union – mentioned in the prior section – which must be identified and addressed appropriately. Non-unions about the elbow present with clinical features common to all non-unions including persistent pain, loss of function, and feelings of clicking or motion within the bone. As with all non-unions, the patient must be screened for signs of infection at initial presentation.

Patients with non-union of the distal humerus usually present with severe stiffness at the elbow. When the patient does attempt to range the forearm through full flexion or extension, motion may occur through the non-union site as opposed to through the joint. In many cases, pain will be present at the supracondylar level, as this is where most distal humerus non-unions occur. A thorough neurovascular exam is required as patients may present with neurapraxia. Bone stock may be especially poor secondary to progressive bone resorption and a windshield wiper effect of loosening hardware; these changes will be evident on radiographic imaging. The status and location of previous skin incisions should be clearly documented.

Non-union of the proximal ulna and olecranon may also present with severe stiffness of the elbow. Again, the patient will present with pain and tenderness. Some degree of instability is generally present, although grossly abnormal motion may not be as apparent as in the distal humerus. However, gross instability and dislocation may be experienced when a considerable portion of the coronoid process fails to achieve union.

Diagnostic Workup

Like all other patient encounters, a thorough history and physical exam are paramount in the diagnostic workup of non-unions about the elbow. The history should account for the mechanism and severity of the initial injury including: high vs. low energy, open vs. closed, associated injuries, what operations have been performed, how many operations have been performed, and any complications thereafter. The post-injury course should also be delineated with special attention being paid to: what residual disabilities are present? Has the patient attended physical therapy? Are there tobacco/substance abuse issues? What is their occupation? To what level of function do they expect to return? Is the injury significantly affecting lifestyle?

Attention is then turned to the physical exam. The exam should focus on presence or absence of pain at the non-union site, ROM at all adjacent joints, neurovascular exam, and status of the soft tissues. Special attention should be dedicated to identifying limb length discrepancies and rotational or angular deformity. Status of the ulnar nerve should be documented. The physician should be careful to determine pain and disability are caused directly by the non-union and not from underlying ipsilateral pathology such as c-spine/brachial plexus injury, rotator cuff tear, chronic pain syndrome, neuroma, etc.

As in all cases of non-union, a workup for infection is required. This generally mandates a CBC, ESR, and CRP. Remember, intra-operative cultures are gold-standard for diagnosing non-union infection and normal lab values for the aforementioned tests do not absolutely rule-out the diagnosis. Aspiration with cell count, gram stain, and culture may also aid in the diagnosis when infection cannot be ruled out.

A thorough history and physical will determine what imaging is necessary. At the very least, orthogonal X-rays that include adjacent joints are mandatory. Plain films allow for classification of non-unions as hypertrophic or atrophic. This will direct the treating surgeon towards the appropriate surgical intervention. When possible, comparison with earlier films should be made. When X-rays are equivocal but the history and physical provide high suspicion for non-union, CT scans should be ordered. Remember, radiographic presence of a non-union does not require surgical intervention if the risk/benefit profile is not in the patient’s favor.

Radiographs should provide clear understanding of fracture pattern, assess quality of previous internal fixation, and quantify the amount of bone loss. A CT with 3D reconstruction may prove invaluable when attempting to determine remaining bone stock, degree of malunion, and surgical planning. Imaging studies should help determine the feasibility of repeat ORIF versus arthroplasty, the need for structural bone graft, and any special tools required for removal of hardware.

The end result of the workup is a diagnosis that confirms presence of non-union, identifies the type of non-union, and potentially elucidates the etiology of the problem. A concrete understanding of the patient, their level of disability, expectation of recovery, and challenges to treatment must be obtained. Once this is accomplished, proceed to pre-operative planning.

Non-Operative Management

The decision for operative vs. non-operative management for non-unions about the elbow is dictated by the presence of symptoms. Patients who present with “painless non-union” and experience no deficit in ROM or functionality require no active treatment. However, when patients experience pain or decreased joint motion and stability, operative intervention is strongly recommended.

Non-operative management may also be pursued if the risk-benefit ratio of surgery is not in the patient’s best interest. If the patient is a poor surgical candidate and likely to sustain adverse consequences as a result of anesthesia or surgical intervention, then continued non-operative management is preferred. Non-operative management should consist of observation, activity modification, physical therapy, and local pain relief measures.

Indications for Surgery

The majority of patients presenting with a distal humerus non-union will be indicated for ORIF. The major goals of the operation are to identify and protect the ulnar nerve, restore and maintain reduction via a rigid construct, stimulate bone healing with bone graft when necessary, and release any associated joint contracture.

Non-unions of the olecranon are indicated for surgery if they become symptomatic; asymptomatic non-unions that maintain adequate elbow function require no active treatment. Indications for surgery include any patient with poor ligamentous stability, inadequate congruity of the sigmoid notch, loss of the triceps extensor function, or poor mobility of the joint. Pre-surgical planning requires separating patients into one of the following four groups, as each group is amenable to different surgical options: 1) infected non-unions, 2) non-unions with minimal damage to the articular surface of the sigmoid notch, 3) non-unions with substantial damage to the articular surface of the sigmoid notch secondary to arthritis or traumatic loss of the joint surface, and 4) non-unions with poor remaining bone stock.

Surgical Technique

Surgical treatment of distal humerus and proximal ulna non-unions share similar goals: restoration of stability, alignment, and articular architecture. The surgeon must also understand when to employ capsulectomy in conjunction with the bony stabilization to avoid excessive stress at the nonunion site. In addition, the treating physician may need to perform ulnar nerve neurolysis for neuropathy, or arthroplasty when the joint is unreconstructable. Attention to these details will ensure the patient has an optimal probability of regaining elbow function.

There are two options available for surgical management of non-unions about the elbow: 1) restore fixation via rigid internal construct (often the most appropriate option) or 2) elbow replacement in cases of unreconstructable intra-articular non-unions or those already possessing post traumatic arthritis. Criteria for internal fixation include adequate bone stock to achieve rigid fixation construct, reversibility of articular pathology that is present, and a patient that will be compliant with a post-operative rehabilitation program. When these three criteria are met, there is a high likelihood that surgical fixation will achieve a desirable outcome. Inability to fulfill all criteria warrants consideration of elbow arthroplasty or non-operative management depending on other clinical factors.

Technique for Distal Humerus Non-Union Repair

Goals of ORIF in distal non-union include: achieve adequate reduction and stable internal fixation, stimulate bone healing with graft substitutes when necessary, protect the ulnar nerve, and release joint contracture to prevent transmission of forces through the non-union site.

During the pre-operative planning stage, the surgeon must decide whether there is a possibility that elbow arthroplasty will be utilized. This decision will determine what approach to the elbow will be employed; if the decision will be made intra-operatively, a triceps-sparing bilateral approach should be utilized to avoid olecranon osteotomy. When there is little doubt that the non-union can be treated with standard internal fixation, a posterior approach with chevron osteotomy provides superb exposure and sufficient work space.

Once the incision is made, attention is directed towards identifying and protecting the ulnar nerve. As most patients will have had previous surgery, there is a high likelihood that the anatomy may be distorted by scar tissue about the surgical site. In this case, dissection may be started several centimeters more proximal to the medial epicondyle so that the nerve is more easily identified. Once identified, the nerve should be tagged and mobilized throughout the length of the operative field. In cases of ulnar nerve neuritis, a thorough neurolysis may provide dramatic improvement.

After the ulnar nerve is addressed and protected, deep exposure may be completed. Upon exposure of the surgical site, tissue should be sampled for pathology and microbiology. Next, soft tissue contracture should be addressed. This requires identification and removal of soft tissue fibrosis and excision of the posterior and anterior fibrotic capsule when present.

The non-union site should now be well visualized. Any sclerotic bone should be excised to ensure apposition occurs between viable bony surfaces. The non-union site is adequately reduced with care taken to avoid excessive flexion/extension, varus/valgus, and malrotation of the distal humerus in relation to the diaphysis. When reduction is satisfactory, bony compression should be achieved between fragments and the need for a structural bone graft should be evaluated and employed when appropriate. When an intracondylar split is present, rigid fixation is usually best achieved with two parallel plates applied to the medial and lateral columns of the distal humerus and secured with multiple long distal screws, similar to the construct used in acute distal humerus fracture fixation. These screws will often interdigitate and increase the construct’s stability. Bone graft is then securely placed within the non-union site.

Technique for Olecranon/Proximal Ulna Non-Unions

The goals of surgery for olecranon and proximal ulna non-unions are to restore congruity of the sigmoid notch, restore ligamentous stability, restore function of the triceps extensor mechanism, and ensure functional mobility of the joint. Operative strategy will largely depend on two factors: amount of joint surface area involved and severity of articular surface damage sustained in the sigmoid notch. If the articular surface is maintained, both excision of the proximal fragment or internal fixation are viable treatment options. When the sigmoid notch has sustained severe damage to the articular surface, excision of the proximal fragment, or distraction arthroplasty are viable treatment modalities.

Excision of the proximal fragment is only indicated if the fragment constitutes less than 50% of the joint surface. This is accomplished by excising the proximal bony fragment and advancement of the triceps tendon to the intact olecranon. When this is done, the anterior surface of the triceps tendon should be directly aligned with the articular surface of the proximal ulna, rather than aligned with the posterior cortex of the ulna. This apposition provides more stable articulation with the distal humerus at the expense of a mildly reduced lever arm.

When the non-union involves greater than 50% of the sigmoid notch, yet the articular surface is generally well maintained, internal fixation provides the best chance at desirable outcome. A successful outcome is contingent on good ulnohumeral reduction, rigid fixation, and bone grafting. Three methods are available for achieving adequate fixation: tension band wiring, plating, and intramedullary lag screw fixation. Tension band wiring may be employed when the proximal fragment maintains adequate alignment. Care should be taken to avoid narrowing of the sigmoid notch, as this may predispose the patient to future arthrosis. Plating may be employed for oblique or transverse non-unions of the olecranon; anatomic plates specifically contoured for olecranon may prove especially useful. In instances of severe comminution or unstable fractures that involve the coronoid process and rupture of the medial collateral ligament, plating may be the only reliable method of reduction. As with tension band wiring, it is imperative that anatomic reduction is achieved and measurements of the sigmoid notch are restored to baseline.

Intramedullary lag screw fixation is appropriate only for single piece oblique or transverse olecranon fractures in which axial compression stabilizes the fracture but does not decrease the olecranon-to-coronoid distance. The lag screw must have sufficient length to gain adequate purchase in the metaphysis of the ulna. Murphy et al. have shown that strength of fixation is superior for intramedullary lag screw coupled with tension band wiring than either entity alone.

Non-unions involving greater than 50% of the sigmoid notch and complicated by destruction of the articular surface warrant consideration for distraction arthroplasty with internal fixation or joint replacement. Distraction arthroplasty involves use of an external fixation device placed to maintain distraction at the ulnohumeral interface. The non-union is first addressed with internal fixation methods described in the previous paragraph, and then the external fixator is placed with approximately 2-3 mm of distraction. Although the mechanism of action remains unknown, Morrey et al. have shown favorable results with this treatment modality.

Joint replacement is reserved for situations where pain and instability are supreme and the patient accepts noticeable limitation in activity; it is considered a true salvage procedure. This modality is effective in elderly patients sustaining severe arthrosis secondary to initial injury. When performed because of olecranon non-union with severe articular surface injury, union can be expected in about 50% of patients. However, the function of a stable undisplaced fibrous non-union is similar to that of a solidly united fracture in the setting of total elbow replacement.

Pearls and Pitfalls of Technique

There are three fundamental principles to successful surgical treatment of non-unions about the elbow: protecting the ulnar nerve, releasing all contractures, and achieving stable fixation with or without grafting. Failure to accomplish all of these goals will result in sub-optimal outcomes.

Identifying and protecting the ulnar nerve is of paramount importance during all non-union operations; failure to do so may damage the nerve and leave the patient with greater impairment than was present pre-operatively. While this may sound like an elementary goal, the surgeon must remember that many non-unions about the elbow may take place in the setting of prior surgical intervention. As such, the anatomy may be distorted by scar tissue and prior nerve transposition. Often times, beginning dissection slightly more proximal to the medial epicondyle will allow identification of the nerve in its proper anatomic relationships. The nerve may then be tracked throughout its course in the surgical field, facilitating identification and tagging of the structure. If the patient presents pre-operatively with motor weakness or paresthesia in the ulnar distribution, a thorough neurolysis may be warranted.

Upon initial evaluation of the patient, any ROM deficit secondary to joint contracture should be noted so that they may be anticipated and addressed intra-operatively. Contractures alter the anatomic mechanical axis of the elbow joint and, in the presence of non-union, may transmit motion forces across the non-union site instead of through the elbow joint. Failure to release these contractures will subject hardware to improper forces and increase the risk of hardware failure and persistent non-union. Therefore, adequate release serves to both increase elbow ROM and protect hardware from undue stress. Any posterior approach to the elbow will provide adequate access for resection of the posterior capsule and posterior band of the medial collateral ligament. The anterior portion of the capsule may then be resected through the non-union site.

As with acute fracture, stable internal fixation is required when surgically correcting non-unions. An unstable construct will permit micro-motion at the non-union site and increase the likelihood of persistent non-union. When choosing the method of internal fixation, the surgeon should opt for the strongest construct that appropriately stabilizes the non-union.

Potential Complications

Infection, persistent-non-union, construct failure, ulnar nerve palsy, and contracture are all potential complications arising from surgical intervention of non-unions about the elbow. The odds of encountering such complications are greatly decreased when applying the basic principles mentioned in prior sections.

Indolent infection should always be ruled out via intra-operative cultures of the non-union site. Remember, the patient with normal lab values and benign X-ray may still harbor an infected non-union. Failure to identify and adequately treat chronic infection of the non-union site may result in acute osteomyelitis, surgical site infection, or persistent non-union.

The risks of persistent non-union and construct failure can be minimized by choosing appropriate internal fixation constructs and performing an adequate capsular release. As mentioned previously, a contracted capsule transmits motion to the non-union site instead of through the elbow; these inappropriate forces are applied to the fixation construct and substantially increase the likelihood of failure. Fixation constructs should be designed for maximal strength within what is appropriate for the non-union. Achieving maximal axial compression is essential when fixing olecranon non-unions because constructs at this site are subjected to distracting forces as the triceps contracts and pulls the proximal olecranon fragment.

Post-operative contracture must also be addressed to ensure beneficial outcome for the patient; if the non-union is fixed but the joint remains functionless due to contracture, the surgery cannot be considered a success. This poor outcome can be avoided by allowing the patient to actively range the elbow through an arc of motion (30-130 degrees of flexion for distal humerus non-unions or 0-90 degrees of flexion for olecranon non-unions) beginning 5-7 days post-operatively. Allowing ROM is contingent on achieving rigid internal fixation at the time of surgery. Heterotopic ossification may still be encountered despite aggressive rehabilitation, but it is usually of little consequence unless encountered in the brachialis muscle or anterior capsule.

Post-operative Rehabilitation

Surgery for non-unions about the elbow is performed to achieve bony union and restoration of motion. Both requirements are necessary to achieve a favorable outcome. Most would agree that bony union is more important than restoring motion, as contracture release may always be addressed with a separate operation if the non-union heals with persistent stiffness. However, both union and functional ROM may be achieved when adequate rehabilitation is implemented. An aggressive post-operative rehabilitation program may only be instituted when the surgeon is confident that stable internal fixation has been implemented.

Distal Humerus Rehabilitation

Immediately post-operatively, patients should be placed in a well-padded posterior splint. On the first post-operative day, they may be fitted with a hinged elbow brace. Active or active-assisted range-of-motion exercises are started under supervision of a physical or occupational therapist, as soon as the soft tissue allows.

The physician should consistently perform a thorough examination at follow-up visits to determine healing stage and correlate with rehabilitation; in other words, healing progression should be matched with physical therapy progression. If motion loss is encountered, the quality and quantity should be documented. Bony motion blocks will be impassable and abrupt, visualized on radiographs, and not expected to resolve with physical therapy. Motion blocks due to early articular adhesions may have an elastic feel at end ranges of motion and may be minimized with increased aggressive physical therapy.

Olecranon Rehabilitation

Similar principles apply for olecranon rehabilitation regiments with one exception: flexion beyond 90 degrees should not be permitted for 4-6 weeks. Olecranon fixation has a tendency to fail in the axial plane, as tension from the triceps insertion is transmitted across the non-union site. This stress can be minimized by blocking flexion beyond 90 degrees until bony union is reliably achieved. In the meantime, patients should be encouraged for early active ROM beginning approximately 5 days after surgery, provided they are placed in a brace locked at 90 degrees of flexion.

Outcomes/Evidence in the Literature

Mitsunaga, M.M., Bryan, R.S., Linscheid, R.L.. “Condylar nonunions of the elbow”. J. Trauma. vol. 22. 1982. pp. 787CrossRef(Mitsunaga et al. published the first report on 25 patients treated with internal fixation for non-union of the distal humerus and demonstrated that up to 30% of patients required additional operations for revision.)

Ackerman, G., Jupiter, J.B.. “Non-union of fractures of the distal end of the humerus”. J. Bone Joint Surg. Am. vol. 70. 1988. pp. 75(Ackerman et al. published on a series of 20 patients and showed that 94% achieved union, but results were fair or poor in 65% of patients; most patients experienced persistent long-term disability despite achieving union.)

Jupiter, J.B., Goodman, L.J.. “The management of complex distal humerus nonunion in the elderly by elbow capsulectomy, triple plating, and ulnar nerve neurolysis”. J. Shoulder Elbow Surg. vol. 1. 1992. pp. 37(Jupiter et al. published a report on six elderly patients with non-union of the distal humerus. The authors emphasized that internally fixing the non-union is not the only goal of non-union operations, and demonstrated that outcome could be improved when attention was directed at protecting the ulnar nerve and resecting contracted tissue. They describe non-unions of the distal humerus as, “a blend of non-union, extreme periarticular fibrosis, and a traumatized and dysfunctional ulnar nerve”. When the goals of surgery addressed all three of the aforementioned pathologies, five out of six patients achieved good or excellent results.)

Helfet, D.L., Kloen, P., Anand, N.. “Open reduction and internal fixation of delayed unions and nonunions of fractures of the distal part of the humerus”. J. Bone Joint Surg. vol. 85-A. Am 2003. pp. 33(Helfet et al. reported on 52 patients and demonstrated that union was achieved in 51 cases. The mean final arc of motion was 94 degrees.)

Ring, D., Jupiter, J.B.. “Operative treatment of osteochondral nonunion of the distal humerus”. J. Orthop. Trauma. vol. 20. 2006. pp. 56(Ring et al. reported on 15 patients, with 12 achieving union and 95 degrees of mean arc of motion.)

Papagelopoulos, P.J., Morrey, B.F.. “Treatment of nonunion of olecranon fractures”. J. Bone Joint Surg. Br. vol. 76. 1994. pp. 627(Papagelopoulos and Morrey reported on 24 patients treated for olecranon non-union, 20 of which underwent operative fixation. Sixteen patients were treated with ORIF and four were treated with ORIF and distraction arthroplasty secondary to severe arthritis. All 20 patients experienced mild to moderate relief of pain after the operation. Of the 16 treated with ORIF, the mean arc of motion improved from 87 degrees to 98 degrees. However, in the four patients in which distraction arthroplasty was used, the mean arc of motion improved from 48 degrees to 95 degrees. All patients experienced an increase in their daily functional abilities.)

Sanchez-Sotelo, J., Morrey, B, Sanchez-Sotelo, J. “Chapter 23: Non-union and Malunion of Distal Humerus Fractures”. The Elbow and Its Disorders. 2009. pp. 349-358. (A detailed and thorough text on the diagnosis and management of distal humerus non-union.)

Papagelopoulos, P, Coonrad, R, Morrey, B., Morrey, B, Sanchez-Sotelo, J. “Chapter 26: Non-union of the Olecranon and Proximal Ulna”. The Elbow and Its Disorders. 2009. pp. 401-418. (A detailed and thorough text on the diagnosis and management of olecranon non-union.)

Smith, W, Pallister, I, Moholkar, K., Ziran, B, Smith, W. “Chapter 6: Non-unions of the Upper Extremity”. Fractures of the Upper Extremity. 2005. pp. 107-147. (A chapter on the management of non-unions in the upper extremity.)

Summary

Non-unions about the elbow lead to a painful, unstable, and poorly functional upper extremity. The treating physician must correctly diagnose the non-union as well as decide on the proper intervention. Good to excellent results can be expected if the patient is compliant with post-operative rehabilitation and the surgeon addresses the three pillars of treatment: rigid fixation, protecting the ulnar nerve, and releasing capsular contractions.

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