Persistent Elbow Instability

Introduction

The osseous and soft tissue constraints of the elbow create a stable articulation with four functional degrees of freedom: flexion, extension, supination, and pronation. Varus and valgus freedom is negligible for functional purposes. The added degrees of freedom afforded by rotation, as well as the obligatory varus stress on the elbow that accompanies shoulder abduction, make instability of this joint more complex than that seen elsewhere. As outlined in other chapters (see Chapter 35, Chapter 36, Chapter 43 ), acute instability can be restored by understanding the mechanism causing instability, the structures damaged, and the reconstructive and rehabilitative algorithms for repair and recovery. Neglected dislocations represent the other end of the temporal spectrum and require a different algorithm (see Chapter 52 ).

There is a subset of elbow instability pathology that has been recognized for some time but first formally examined in 2007. Persistent elbow instability (PEI) was defined as continuous subluxation or dislocation after initial treatment for an elbow dislocation with a coronoid fracture. This instability, presenting as incongruity of the ulnohumeral joint, is present on static radiographic examination and persists despite the initial orthopedic management ( Fig. 49.1 ). The initial management may be as simple as a closed reduction. Typically, the initial treatment is more complex, including radial head repair/arthroplasty/resection, coronoid fixation, proximal ulnar fixation, and collateral ligament repair. The incongruity of PEI is different than the “drop sign,” which typically resolves with return of muscle function, when present after dislocation or fracture–dislocation ( Fig. 49.2 ).

$FIG 49.1, Persistent elbow instability. (A) Initial fracture–dislocation with incongruous ulnohumeral articulation. (B) Surgical intervention consisting of a radial head resection and fixation of the ulna fails to keep the elbow reduced.$

$FIG 49.2, “Drop sign”: in contrast to persistent elbow instability (PEI). There is increased distance between the ulna and distal humerus, yet the joint remains congruous. This may be noted with or without fracture and may occur after surgery. This is in contrast to PEI where there is loss of congruency of the joint.$

The last 25 years have seen a coalescence of information relating to the understanding of elbow instability. Dissemination of now well-understood mechanisms of injury and resultant pathology has taken much of the unpredictability out of the treatment of acute elbow fracture–dislocations. PEI represents a higher level of complexity of elbow pathology, one which is better understood now than in 2007 but one for which reliable and reproducible solutions are still sought.

The initial report in 2007 defined the definitive treatment to gain stability as the “index” operation. The same definition for PEI and index operation will be utilized in this chapter. Reports subsequent to 2007 have provided more information on PEI, but there is yet to be a reliable treatment algorithm like the one that has been developed with posterolateral rotatory instability with dislocation, radial head fracture, and coronoid fracture (the terrible triad). Papandrea et al. identified clinically significant worse outcomes when the index operation was delayed for more than 6 weeks from the original injury. This window was noted again in the study done by Sørenson and Søjbjerg in 2011.

The treatment for PEI is difficult and not uniformly successful ( Fig. 49.3 ). Multiple factors must be taken into consideration when planning for reconstruction. Initial evaluation should include consideration for salvage with fusion or arthroplasty, if the articulation has been damaged such that a congruent and painless joint surface cannot be restored. Despite the difficult nature of these cases, the comprehensive principles are simple: the elbow needs to be congruent in all planes, there need to be enough osseous constraints to keep the elbow reduced in the long term, the osseous structures need adequate support (temporary or permanent) to result in long-term stability, and sufficient ligamentous tissue support needs to be present, reconstructed, or supported until healing is concluded.

$FIG 49.3, Attempted reconstruction of persistent elbow instability. Anteroposterior (AP) (A) and lateral (B) of a fracture–dislocation after reconstruction with a radial head and repair of the lateral ulnar collateral ligament. The joint is pushed by the overextended radial head prosthesis into varus, as demonstrated by the overhang of the sublime tubercle on the distal humerus. Postoperative AP (D) and lateral (C) of the index operation. The distal humerus was partially resurfaced, the collaterals were reconstructed, and a revision to the radial head was done. At the time of surgery, the coronoid was repaired with sutures. Images reveal that while there has been improvement in the static varus alignment, the coronoid did not heal in a position to provide adequate buttress. Clinically, the patient still has varus/valgus instability. This case may have benefited from more rigid fixation of the coronoid with a buttress plate or even an allograft.$

Etiology

PEI occurs after an elbow fracture–dislocation, and the resultant instability is not definitively resolved by the initial intervention. The occurrence of PEI in and of itself does not indicate substandard care by the initial treating physician. It can occur even in the most experienced hands.

PEI can be the result of incomplete recognition and treatment of the initial trauma. This includes utilizing closed reduction and casting for some fracture–dislocations. Simple closed treatment can work for complex elbow fracture–dislocations, but success with this is the exception rather than the rule. Closed treatment is appropriate when there is little to no displacement and the elbow appears stable after reduction. As long as the postreduction parameters are acceptable and continue to be met with close clinical and radiographic surveillance, this treatment can be successful. It is imperative that the treating surgeon follow this type of injury closely, as PEI is often generated from what initially was felt to be a stable injury. Loss of reduction does not indicate definite failure, as long as it is diagnosed without delay. The literature has thus far demonstrated poor outcomes after 6 weeks of PEI. Even before 6 weeks, if an elbow remains dislocated or subluxed in a cast or splint, cartilage damage, bone loss, and soft tissue contracture can occur, making index treatment more difficult. For this reason, it is critical to image an elbow fracture–dislocation frequently (at a minimum of every 2 weeks) when closed treatment is chosen. If PEI develops, it should be treated immediately to mitigate significant damage or contracture.

The mechanism of injury leading up to PEI often includes a fall on an outstretched hand from variable height but may also include axial load sustained during a deceleration injury such as a motor vehicle accident. The resultant pattern of injury depends not only on the axial load but also on the varus or valgus component of force and position of forearm rotation during the moment of impact. The injury may produce posterolateral elbow rotatory instability (PLRI), posteromedial rotatory instability (PMRI), or a transolecranon elbow fracture–dislocation (a Monteggia variant) (see Chapters 36 and 42 ).

Acute Injury Patterns That Can Lead to PEI

PLRI

Posterolateral rotatory instability is now a well-defined pattern of injury that typically occurs from a fall on an outstretched hand (see Chapters 36 and 71 ). Axial load is applied to the hand/forearm while the elbow sustains a valgus stress and a supination rotational force. The acute treatment is discussed in Chapter 35, Chapter 36, Chapter 71 . PLRI may result in a simple elbow dislocation, but following reduction, this type of injury is typically rendered stable. Recurrent instability is the repeat subluxation or dislocation from a reduced position that results from an unhealed lateral (ulnar) collateral ligament. Repair (if acute) or reconstruction (if chronic) of the lateral ulnar collateral ligament (LUCL) will render this recurrent elbow instability pattern stable and is covered in Chapter 71 . Persistent instability, which is distinctly different from recurrent instability, is rarely, if ever, the result of a simple elbow dislocation. In simple dislocations, by definition, there is no bony compromise, and generally the flexor-pronator mass and common extensor mass remain largely intact, which provides sufficient stability to allow for concentric healing of the injured collateral ligaments, even with early mobilization. Rarely, a high-energy dislocation occurs without bony injury but with complete disruption of the flexor and extensor tendon origins from the epicondyles, known as an “internal degloving” injury. The absence of the stabilizing effect of the ligaments and muscular stabilizers can render the elbow persistently unstable without bony injury, and surgical management may be required to maintain joint congruity. This is an unusual situation with a distinct clinical appearance of massive swelling, which is generally recognizable. If there is persistent subluxation of the ulnohumeral joint on a static radiograph after what appears to be a “simple” elbow dislocation, additional imaging of the joint should be obtained and the coronoid assumed to be fractured until proven otherwise.

PLRI often results in a fracture of the coronoid, the radial head, as well as a dislocation—the so-called terrible triad injury. The acute treatment of this injury has been well described, and successful algorithms have been developed for the treatment (see Chapter 43 ). Despite the proven treatment for terrible triad injuries, stable joint reduction is not always achieved with the initial management. Pitfalls to successful management include failure to restore radial head stability, neglected or inadequate repair of the LUCL complex, and failure to recognize the contribution of the coronoid fragment to the anterior joint “buttress” resisting posterior translation, especially in elbow extension.

Acute PLRI repair does not need to include the repair of smaller coronoid fractures, so long as the radial head is repaired or replaced, and the soft tissues, including the lateral collateral ligament (LCL) are repaired such that the elbow is stable. Underestimating the size of the coronoid fracture and not fixing it may lead to PEI. During surgical treatment of a terrible triad injury, testing the stability of the elbow after reestablishing radial head stability and LUCL competence should reveal if the coronoid fracture is critical to elbow stability. Although more common with PMRI, unappreciated extension of the coronoid fracture into the sublime tubercle may contribute to PEI.

PMRI

PMRI has been more recently described and defined (see Chapter 30 ). This injury occurs after an axial load but with a varus stress and pronation of the elbow and forearm (see Chapter 36 ). This pulls the lateral side of the joint open, preserving the radial head from fracture, but still tearing the LUCL. The medial trochlea is driven into the base of the medial coronoid, causing a range of fractures, from small impaction injuries at the sublime tubercle to comminuted, multifragment fractures of the coronoid ( Fig. 49.4 ). Less commonly, there may be smaller tip fractures of the coronoid if the trochlea “rides up” on the coronoid, instead of driving through it. These smaller fragments may not include the articular portion of the sublime tubercle but still can have subluxation of the ulnohumeral joint ( Fig. 49.5E ).

$FIG 49.4, (A) Anteroposterior view of an elbow after varus posteromedial injury. Note the impaction to the joint surface, which occurs from the trochlea being driven into the medial face of the coronoid. There is no radial head fracture. A subtle widening of the radiocapitellar joint indicates injury to the lateral ulnar collateral ligament. (B) Computed tomography scan of the same patient demonstrates the extent of damage to the articular surface of the ulna that would be expected to cause arthritis if left untreated.$

$FIG 49.5, (A) Anteroposterior radiograph of an elbow with varus posteromedial rotatory instability (VPMRI) looks innocuous. (B) Oblique radiograph shows medial joint incongruity. (C) Lateral radiograph appears to have congruous joint but does show abnormality at the coronoid. (D) Three-dimensional (3D) computed tomography (CT) scan demonstrates fracture of the anteromedial coronoid. (E) Joint incongruity from VPMRI clearly demonstrated on 3D CT.$

PMRI almost always includes a fracture to the coronoid, and although it may be small, it is usually clinically significant. PEI may develop after PMRI injuries when the pathology is underappreciated. Lateral radiographs are usually unremarkable, often showing only a small “chip” fragment off of the coronoid without significant disruption of ulnohumeral congruity. Since the radial head is not fractured, the lateral side of the elbow is often felt to have avoided injury. On the contrary, the LCL is typically torn, and lack of varus restraint on the lateral side increases the stress on the coronoid medially. Small medial coronoid fractures often involve the sublime tubercle. With the loss of lateral support, the medial trochlear surface “rests” in the defect of the sublime tubercle coronoid fracture, rendering the joint incongruous. If not rectified, this will lead to subtle yet clinically significant PEI ( Fig. 49.5 ). Although large case series are not available, individual clinical experiences have demonstrated that this continued subluxation will lead to rapid posttraumatic osteoarthritis.

Transolecranon Fracture–Dislocation

Transolecranon fracture–dislocation may be deceptively complex, especially to the unsuspecting or less experienced surgeon. The end of the humerus is driven through the olecranon, causing a fracture. The comminution may be severe, typically extending into the coronoid ( Fig. 49.6 ). The radial head is usually not spared and will often sustain a fracture to at least part, if not all, of the head and/or neck. Ulnohumeral stability after rigid fixation of the ulnar fractures is dependent on the status of the attachment of the collateral ligaments to the sublime tubercle and christa supinatoris. At times, these ligament attachments are fractured from the body of the olecranon. Failure to include these fractured attachment sites in the olecranon fixation may lead to PEI. Disruption of both the proximal and distal ends of the collateral ligaments is extremely rare.

$FIG 49.6, (A) Lateral radiograph of a transolecranon fracture–dislocation. There is significant comminution, and it is difficult to appreciate the anatomy of the coronoid. (B) Anteroposterior view of the same patient demonstrates alignment of the medial coronoid to the humerus, with the appearance of a relatively simple olecranon fracture pattern. The radial head dislocation is apparent. (C) An attempt at fixation neglected to address the coronoid fragment, which is incongruous with the distal humerus at the medial joint. This is, by definition, persistent elbow instability.$

Transolecranon fracture–dislocations are typically obvious in the damage caused, yet PEI still may result from the underappreciation of the role of the fractured coronoid ( Figs. 49.6 and 49.7 ). There can be difficulty in treating the medial coronoid fracture fragments due to a lack of access, once the major fracture fragments are reduced and stabilized.

$FIG 49.7, Lateral radiograph of an elbow with persistent elbow instability. Anatomic fixation of the olecranon to shaft was done with K-wires and a tension band. The coronoid fracture fragment was not secured, and the humerus has subluxed anteriorly.$

Underestimating the size or importance of the coronoid fracture can lead to the development of PEI, which can develop in all three types of injuries: PLRI, PMRI, and transolecranon fracture–dislocations. Recognition alone of the importance of the coronoid fracture is not enough. The fixation must not only be anatomic in the load-bearing portions but mechanically sound enough (on its own, or augmented) to withstand the posterior vector forces applied by the brachialis, biceps, and triceps muscles, which occur even in the immobilized elbow. Failure to anatomically reduce and provide fixation for clinically significant coronoid fractures will leave a patient at high risk for collapse of the fracture and the development of PEI.

Additional Considerations: Etiology

Body Habitus

The obligatory varus stress to the elbow with shoulder abduction can be mitigated with proper body mechanics. Bracing may also help, but the brace must fit. Obese body habitus can negatively affect both. The obese patient may have anatomy that precludes the ability to have true neutral position of the shoulder in relation to abduction/adduction, because the humerus is always levered into abduction by soft tissue. An abundant soft tissue envelope also precludes accurate fitting of a brace, as the brace may shift distal, or rotate, both of which will misalign the brace's center of rotation (COR) with the patient's true COR.

External fixation, previously the only effective treatment to add exogenous skeletal stability to an elbow, is more difficult to utilize in the arm of an obese patient. When additional stability is deemed necessary in this patient population, bridge plating or an internal joint stabilizer may be indicated (see Chapter 48 ).

Noncompliance

Noncompliance may be the most difficult of all causes of PEI to rectify. If a patient is unwilling or unable to follow directives to maximize the chance of a good recovery, it is hard to justify treating PEI.

Medical Comorbidities

Issues known to affect healing, such as smoking, poorly controlled diabetes, and malnutrition, as well as many other metabolic disorders, should be addressed prior to surgery if possible. Although excessive delay in treatment of PEI is to be avoided, aggressive treatment of medical issues such as insulin-dependent diabetes mellitus (IDDM) and nutritional status should be addressed to minimize risk and facilitate healing. Smoking cessation cannot be overlooked and falls into the category of patient compliance. Nicotine supplements such as patches or gum may be helpful for smoking cessation but still contribute to decreased tissue perfusion and are less desirable than abstinence. Patient understanding of the gravity of the situation can be a powerful motivator.

Treatment

Reconstruction for PEI has been reported in several small studies. The injury pattern, treatment algorithms, and outcomes have been heterogeneous, making evidence-based recommendations difficult. Before reconstruction is undertaken, the quality of the joint surface needs to be considered. If the cartilage quality is not sufficient for function, salvage should be considered by fusion or total elbow arthroplasty ( Fig. 49.8 ).

FIG 49.8, The initial step once persistent elbow instability (PEI) has been diagnosed is to determine if reconstruction or salvage is more appropriate.

When a surgeon and patient encounter PEI, there needs to be understanding by both parties of the complexity of the situation and the importance to recreate a stable elbow in a timely fashion. As previously noted, there is a narrow window for success that appears, at least with current techniques, to close after approximately 6 weeks from the initial injury. While timing is important, surgical reconstruction must be carefully planned and executed.

The proper workup of PEI includes obtaining a history, physical examination, imaging, and potentially laboratory work. Only then can definitive surgical planning begin. In addition to the typical parameters followed, evaluation of the PEI patient requires a level of detail that many orthopedic injuries do not require. Any previous documentation should be reviewed, including all previous operative notes. After an understanding of the etiology of the PEI, as well as a proper workup, one can begin the process of reconstructive planning. There are basic tenets that, if followed, should lead to a stable elbow, at least in the operating room. With PEI, the challenge occurs not only in getting to this point but also in maintaining the stability throughout the recovery and rehabilitation to provide long-term stability, decreased pain, and improved function. Stability is more important to obtain than motion. A stiff but stable and concentric elbow is preferred to one with motion and subluxation or instability.

Preoperative Treatment

History

The history should include details of not just the interventions, but also the original injury. Soft tissue injury, especially open fractures, should be well understood by the treating surgeon. If surgery was performed, any issues of delayed or problematic wound healing may indicate an indolent infection. An understanding about whether the elbow was initially stable after surgery and subsequently became unstable or whether the injury was never adequately stabilized may be helpful. Nerve injury, either prior to the original injury or subsequent to any treatment, needs to be delineated.

The reconstruction of the elbow with PEI depends on many factors. One of these factors is whether the PEI is the result of an untreated injury or a failure of previous surgical treatment. In the former situation the bony and soft tissue elements, although damaged, are present in their injured location, and there is no iatrogenic tissue scarring. As noted previously, with passing time, there may be bone and cartilage loss from intact or damaged articular surfaces wearing against other osseous structures, since the joint is not congruent. Therefore, even without surgical intervention, PEI has the propensity for altered anatomy. The presence of failed hardware may have caused additional soft tissue or articular injury. In the latter case, the failed or ineffective fixation (plates, screws, anchors, suture arcades, etc.) must be removed or revised to allow revision surgery to proceed. Caution should be exercised to avoid additional tissue damage during removal. Attention should be paid to the absence of normal bony constraints. Radial head removal is obvious, but excision of relevant coronoid fragments may not be appreciated, especially if a radial head prosthesis is obscuring visualization.

A thorough understanding of the patient's social situation, including stressors and supports, as well as physical demands from ambulation, activities of daily living, occupation, and avocations, needs to be determined. Substance use including nicotine, alcohol, and illicit drug history should be obtained. Although rare, any metal allergies should be determined before reconstruction. The patient and his or her support system need to be engaged to understand the magnitude of the injury and likely less than normal outcome from even the most successful treatment.

Physical Examination

Examination should focus on the soft tissue envelope, previous incisions, and any signs of infection. In rare instances, plans will need to be made for flap closure (local or remote); it is best to preplan for this, rather than making coverage decisions at the end of a challenging case. Concerns regarding infection should prompt the surgeon to consider an infectious disease consult and inform the patient that his or her surgery may need to be staged, if indeed infection is present or suspected. If there is uncertainty, frozen sections should be obtained during surgery from multiple locations and depths of dissection and evaluated for the presence of white blood cells. Although it is best to discuss the specifics of the specimen with the pathologist, concern is usually raised when there are more than five to ten white blood cells per high-power field (5–10 WBCs/HPF). Unfortunately, indolent infection with Propionibacterium may fail to demonstrate pathologic changes on frozen specimens. For this reason, cultures should also be obtained and held for at least 17 days.

The patient with PEI has often been struggling with this injury during the perioperative period. The news that the elbow is not healing properly and may require additional surgery will add to the patient's level of stress and frustration. The elbow will be stiff, and there is little gained by attempting to maximize elbow motion for measurement. It is still paramount to assess motion, not just for comparison to postoperative measurements but, more important, to objectively demonstrate to the patient his or her current limitations. This also provides a framework to discuss realistic expectations following surgical intervention for PEI. Therefore, accurate measurement of the range of motion (ROM) in the flexion and extension plane as well as supination and pronation should be attempted. Presence and location of crepitus should be assessed, along with evidence of objective instability or patient apprehension. Motion and function of the ipsilateral shoulder, wrist, and hand should be documented. Hand swelling and functional limitation combined with shoulder stiffness often coexist with PEI. Instituting therapy preoperatively to address the uninjured joints may facilitate postoperative rehabilitation efforts.

It is imperative to determine if there is sensory and/or motor dysfunction and to document this accurately. Sensory and motor nerve function of the radial, ulnar, and median nerves (including the anterior interosseous nerve) should be recorded. Any deficit should be identified and discussed with the patient. Due to the magnitude of elbow dysfunction, it is common for the injured patient to overlook significant distal pathology, especially intrinsic muscle paralysis or paresis from ulnar nerve damage. Cutaneous neuromas should also be sought out on examination, such that a patient understands they exist prior to an index operation and for consideration of neurolysis or neurectomy.

Imaging

PEI is never a simple situation, and the successful reconstruction is often elusive. Because of this, as much useful radiographic information as possible should be gathered prior to formalizing a plan of reconstruction. Adequate imaging is paramount to understanding PEI, both its causes and potential solutions.

Coonrad et al. describe a “drop sign,” an increased ulnohumeral distance on static lateral radiographs after simple elbow dislocation (see Fig. 49.2 ). There was speculation that this could indicate persistent instability of the elbow. Duckworth et al. reviewed radiographs of the elbow after treatment of a dislocation or fracture–dislocation in patients who demonstrated a “drop sign.” All 23 patients were treated with active exercises and avoidance of varus stress and maintained long-term elbow stability. While a “drop sign” is worth noting, it does not appear to be a harbinger of PEI.

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