Malunion of Hand Fracture

Patterns of malunion

Malunion is the most common bony complication of phalangeal fractures. The following four patterns of deformity are recognized:

• Malrotation
• Volar angulation
• Lateral angulation
• Shortening

Malrotation usually is seen after oblique or spiral fractures of the proximal and middle phalanges. The best method of assessing malrotation is to ask the patient to make a fist and look for digital overlap.

In adults with proximal phalangeal fractures, volar angulation exceeding 25-30° may result in pseudoclawing. This deformity makes using the hand awkward and can result in a fixed flexion contracture of the proximal interphalangeal (PIP) joint. The appearance may be aesthetically unacceptable.

Lateral angulation and malrotation often occur concomitantly. If correction is considered, the components of the deformity must be carefully identified.

Shortening may occur after a comminuted fracture is allowed to heal in a collapsed fashion or after a long spiral fracture.

In malunion of metacarpal neck fractures, sunken knuckle may be the clinical presentation. It is more of a cosmetic problem than a functional problem. In metacarpal shaft malunion, tendon imbalance and intrinsic contracture of the PIP joint may occur; however, function may still be preserved.

Other aspects of malunion

Intra-articular malunion occurs when intra-articular anatomy is not restored. Unreduced condylar fractures that extend into the PIP joint may produce pain, angulatory deformity, limited mobility, and, ultimately, degenerative arthritis.

Regarding metacarpal fractures, malunion can follow a transverse fracture, which results in dorsal angulation in the sagittal plane. Compensatory hyperextension (pseudoclawing) at the metacarpophalangeal (MCP) joint can result. Malunion after a spiral or oblique fracture results in malrotation. In patients with second and third metacarpal fractures, dorsal angulation is bothersome both cosmetically (pseudoclawing) and functionally. The prominent metacarpal head in the palm can be painful when the individual grips.

Rotational malunion of metacarpal fractures results in overlapping of the affected finger over an adjacent finger. The cosmetic deformity is often marked, and the grip is often impaired.

After crushing injuries or open fractures, shortening and associated problems of the soft tissue (eg, tendon adhesions, poor skin coverage, neurologic deficit) may occur.

Malunion most commonly affects the scaphoid among the carpal bones. Malalignment after union is evident as carpal collapse initially, and is reflected later in direct measurements of intrascaphoid alignment. The lateral appearance on radiographs shows the typical humpback scaphoid, which describes a deformity resulting from flexion angulation between the proximal and distal poles. Scaphoid malunion can alter carpal mechanics, leading to pain, weakness, limited motion, and degenerative arthritis.

Relation between metacarpal shortening and joint function

Some authors have performed cadaveric studies to find the relationship between metacarpal shortening and extension of the MCP joint or the PIP joint. Strauch et al observed that for every 2 mm of shortening of the metacarpal, there was a 7° lag in extension of the MCP joint.[5] However, this is not seen clinically, because of the ability of the MCP joint to hyperextend.

Vahey et al found that for every 1 mm of shortening of the proximal phalanx, there was a 12° lag in PIP joint extension.[6] They also found that there was a linear relation between shortening of the proximal phalanx and lag in PIP joint extension and that increased angulation of the phalangeal fracture led to increased lag in extension of the PIP joint.

Malunion of hand fractures may result from inadequate treatment or failure of treatment. Accurate anatomic restoration may not be the goal of nonoperative treatment or even certain operative treatments for hand fractures. Hence, inaccurate anatomic restoration after treatment may not be considered evidence of inadequate treatment.

Most fractures of the hand bones occur in young, active adults who are involved in many various occupational and sporting activities. If these fractures are not managed carefully, they may result in malunion. This may lead to loss of function due to malalignment, malrotation, or shortening, which may result in decreased and disordered motion of fingers and poor outcomes.

The frequency of malunited fractures may be high in the hands, but few of these malunions require treatment. This is especially true with malunion of metacarpal neck fractures of the little fingers, which seldom produce deformity or interfere with function and therefore typically require no treatment.[2] In a study by Tubiana, out of 10,000 hand injuries, only 30 malunions required treatment.[7]

If treated carefully, with adherence to the principles described (see Treatment), most phalangeal and metacarpal malunions heal without clinically significant complications. Complications may include recurrence of deformity, neurovascular complications, or both.

Some patients may develop stiffness and decreased mobility. Most poor results are documented in elderly patients (>65 years) and in patients with crush injuries or extensive soft-tissue contractures. A combination of these factors increases the risk of compromised results. Proper selection of implants and quick rehabilitation may improve the prognosis.

In a study comparing 218 little-finger metacarpal shaft and neck fractures treated nonoperatively (with no attempt at fracture reduction) with 44 treated operatively with fracture reduction and fixation, severity of palmar angular deformity did not affect the outcome of nonoperatively treated fractures.[2]  There were no differences in outcome between operatively treated and nonoperatively treated metacarpal neck fractures; and Disabilities of the Arm, Shoulder, and Hand (DASH) scores and aesthetic outcomes were better for metacarpal shaft fractures treated nonoperatively than for those treated operatively.

Potenza et al reported clinical and radiographic medium-term results for 24 fingers in 20 patients who underwent surgery for posttraumatic malunion of the proximal phalanx.[8]  In all cases, corrective osteoclasia or osteotomy was done at the malunion site, followed by miniplate and screw fixation or by screw fixation only. Corrective osteoclasia was performed when malalignment was addressed within 6 weeks after injury. Two patients who had two fractures underwent additional surgery to improve function and range of motion.

Final follow-up occurred at a mean of 24 months after corrective surgery.[8]  Good or excellent clinical and radiographic results were obtained for all patients. An improvement in grip strength was demonstrated by all patients. The mean score on the DASH symptom scale was 5 points. The researchers concluded that osteotomy in situ, in conjunction with stabilization by miniplates or screws, is effective for correcting posttraumatic malunions of the proximal phalanges of the fingers.

Malunited hand fractures are not usually difficult to diagnose. Most patients provide a history of injury associated with the deformity. The form of treatment the patient received should be noted. Such treatment may include both nonoperative measures (eg, splinting, immobilization, or physiotherapy) and operative measures (eg, internal or external fixation).

The patient history must include the following:

• Age
• Occupation
• Hand dominance
• Function and restriction of hand function after the fracture
• Effect of the malunion on his or her activities

Commence the hand examination by comparing the affected hand with the uninjured hand. Note any obvious swelling or deformity. Look for the anatomic bony landmarks and their relations with each other, and compare them with those of the healthy hand. Abnormal positioning may indicate a malunited fracture or tendon rupture or adherence. The deformity should be categorized in each plane, including the ulnar-radial plane and the volar-dorsal plane. Also important is the rotational alignment. (See the image below.)

The most important aspect of the examination is the functional assessment of the hand. Because the fingers converge with flexion and diverge with extension, certain deformities can be appreciated with the fingers in flexion. The ability to make a complete fist must be assessed. Because the flexor digitorum profundus tendons of the fingers work in unison, any restriction in the movement or decrease in the length of one finger may seriously affect the power of the patient's hand grip. Hence, it may notably interfere with normal function of the hand.

Grip strength should be measured by using a dynamometer, and the results can be compared with those of the healthy hand. Normal maximum grip strength is 52 kPa in men and 31 kPa in women. The pinch-grip strength can be measured by using a manual pinch meter. However, a pinch-grip analyzer can be used to measure both pinch and grip strengths, and it may be a useful tool for objectively assessing hand function.

The examination must include neurologic and vascular assessments. Any previous scar due to surgery or injury should be assessed to facilitate the planning of incisions if surgery is contemplated.

Most malunited fractures of the hand can be detected with the help of plain radiography. The three common views (ie, anteroposterior, lateral, and oblique) yield adequate information.

Computed tomography (CT) and magnetic resonance imaging (MRI) may be helpful in the assessment of complex articular injuries or carpal injuries. Three-dimensional (3D) planning based on CT data may provide useful data about the deformity, facilitate the development of patient-specific instruments, and improve the accuracy of surgical correction.[9]

In cases of carpal bone fractures, radioisotope scanning may be useful.

Indications for surgical treatment of hand malunion include the following:

• Pain
• Loss of function
• Cosmetic deformity
• Loss of motion in the neighboring joint
• Bony exostosis causing skin irritation and posing a threat of tendon attrition

When treating hand malunions, one must remember that the potential risks of surgery (eg, tendon adhesions and joint stiffness) may outweigh any anticipated advantage.

The absolute contraindication for surgery is local infection. Relative contraindications include a functionless limb, poor bone quality, and poor general medical condition.

In the future, expanded use of bioabsorbable implants made of polyglycolic acid or poly-L-lactic acid may have advantages over the traditionally used pins, screws, and plates. These bioabsorbable plates will help avoid the need for second procedures to remove implants, which are the main causes of loss of function from iatrogenic causes. Further development of low-profile implants with high tensile strength will allow adequate mobility during postoperative rehabilitation and thereby help prevent stiffness.

The hand is a highly complex structure that requires integrated function of extrinsic and intrinsic motor units across a complex and limited bony and articular framework. The hand also functions as a sensory organ and an organ of communication. All these factors should be considered before reconstruction is undertaken.

Goals of surgical treatment

The goals of treatment are to restore disordered function and, occasionally, to correct cosmetic deformity. Accordingly, the malunion should be carefully studied with an eye to understanding the original deforming forces. Important principles in the management of malunions include the following:

• Rotational deformities are most disabling yet frequently not appreciated; a 10° rotational malunion results in a 2-cm overlap at the fingertip; alignment should always be checked with the fingers flexed in the palm
• An appropriate form of osteotomy and subsequent fixation must be tailored to each individual deformity; familiarity with osteotomy techniques and alternative forms of fixation affords flexibility in treating deformities
• The soft tissues must be inspected carefully for scarring, adhesions, and contractures; careful protection of delicate structures by judicious tenolysis and arthrolysis may be needed at the time of osteotomy
• Appropriate, functional postoperative rehabilitation is a must for good results; otherwise, even the best surgery produces suboptimal results

A carefully planned osteotomy is necessary and must be executed with the least possible further damage to soft tissues. Techniques of osteotomy must be tailored to the biomechanical requirements for proper realignment of the malunited fracture.

Seo et al described an osteotomy technique for correcting malunion of the proximal phalanx that is minimally invasive and is performed under local anesthesia.[10] They reported that this technique has the advantage of permitting active flexion and extension, which leads to more accurate reduction and earlier recovery.

Preparation for surgery

Adequate surgical planning requires adequate preoperative assessment. The patient's neurovascular status should be assessed before any intervention is performed. Intraoperative fluoroscopy or radiography should be used to ensure that adequate fixation is achieved before the patient leaves the operating room. Joint motion should be assessed after fixation so that postoperative expectations can be established.

Malunion of phalangeal fractures

Clinically significant malrotation results in functional impairment and usually necessitates osteotomy through the phalanx or the metacarpal. (See the images below.)

Phalangeal osteotomy corrects the malunion at its site of origin, allows simultaneous correction of angular deformities, and permits concomitant soft-tissue procedures such as tenolysis or capsulotomy. Phalangeal osteotomies can be either step-cut[11] or transverse, which are performed with a power saw. Step-cut osteotomies are fixed with either small AO (Arbeitsgemeinschaft für Osteosynthesefragen [Association for the Study of Osteosynthesis]) screws or Kirschner wires (K-wires); transverse osteotomies can be held with a plate or with K-wires.

Metacarpal-base osteotomies[12] for malrotation correction can achieve up to 18-19° of correction in the index, long, and ring fingers and up to 20-30° in the small fingers.

Volar angulation of 25-35° results in fixed flexion deformity of the proximal interphalangeal (PIP) joint. This requires correction by means of either closing- or opening-wedge osteotomy and fixation with K-pins. The opening wedge requires a bone graft to fill the gap, whereas the closing wedge may result in shortening of the finger.

Lateral angulation of phalangeal fractures is corrected in the same manner as volar angulation—that is, by performing osteotomies with a power saw.

Shortening due to a comminuted fracture that is allowed to heal in a collapsed fashion or that occurs after a long spiral fracture can be corrected with an appropriately fashioned intercalary graft insertion. When a spiral fracture of the phalanx heals in a shortened position with a distal spike on the proximal fragment, blocking flexion of the digit, careful removal of the spike may be all that is required.

Unreduced condylar fractures extending into the joint require corrective osteotomy, arthrodesis, or arthroplasty.

Malunion of metacarpal fractures

Dorsal angulation usually occurs in the second or third metacarpal and is bothersome, both cosmetically and functionally, in that it weakens the grip of the hand (see the images below). Correction is achieved with closing- or opening-wedge osteotomies or fixation with K-wires or AO plates.

The closed wedge is preferred over the open wedge for two reasons. First, healing of only one surface is required, unlike the open wedge, in which healing of two surfaces is required. Second, the intrinsics can accommodate some shortening with a closed wedge, whereas with an open wedge, lengthening of the bone occurs. Such lengthening may aggravate the intrinsic tightness, especially when posttraumatic intrinsic muscle contracture has occurred.

Rotational malunion results from overlapping of the affected finger over the adjacent finger. Cosmetic deformity is often marked, and grip is impaired. Correction is achieved through a metacarpal-base osteotomy.[12] During the operation, a longitudinal mark is made on the metaphysis with an osteotome prior to the osteotomy. Then, the osteotomy is performed with a power saw perpendicular to the mark. The rotation is corrected and fixed with several K-wires or AO plates.

Intra-articular metacarpal malunions are difficult to correct with osteotomies. However, correction can be achieved by maintaining reduction with screws and plates or with screws and cancellous bone grafts.[3]  Treatment with K-wires and a costal cartilage graft has been reported.[13]

Malunion in carpal bones

The scaphoid is the usual site for carpal malunion.[14] Malunion of other carpal bones is rare. Malunion of the scaphoid is best prevented. If malunion of the scaphoid is detected soon after union, corrective osteotomy can be considered. Late malunion of the scaphoid is best managed symptomatically. Finally, scaphoid cheilectomy or radial styloidectomy can be considered if symptoms persist.

Optimal site for osteotomy

Whether osteotomy for malunion of metacarpals and phalanges in the hand should be done at the original fracture site or at a separate site is a matter of debate. Correction at the fracture site is generally preferred, in that it addresses the issue at the site of pathology (ie, malunion) and thus can correct the combined deformity (translation, rotation, and angulation). Furthermore, it enables the surgeon to perform tenolysis and capsulolysis at the same time. It especially avoids the zigzag deformity produced by the osteotomy away from the fracture site.

A corrective osteotomy performed at the level of the fracture site is called a focal osteotomy, whereas one performed away from the original fracture site is called an extrafocal osteotomy.

Extrafocal osteotomies do not restore the normal anatomy. However, there are instances where this may be preferred, as in the case of a malunion resulting from a complex or compound fracture that can be treated by a single osteotomy rather than a focal osteotomy. The latter may have to be complex, and the metacarpal or the phalanx may not lend itself to such a complex procedure. Extrafocal osteotomy is also preferred in articular malunions when there is enough joint space or if the articular fragment is too small to be interfered with.

Opening-wedge vs closing-wedge osteotomy

Basically, an osteotomy can be a closing-wedge or an opening-wedge procedure. A closing-wedge osteotomy has the advantage of inherent stability with no additional bone graft; however, it shortens the digit. An opening-wedge procedure may need a structural bone graft, but this is not always the case, as when secure fixation is obtained with a plate and screw, where cancellous bone graft can be used as supplementation.

Karthik et al reported good long-term results from the use of closing-wedge osteotomy with temporary intramedullary K-wire and plate fixation to treat 14 symptomatic malunited metacarpal fractures in 12 patients.[15]  At a mean follow-up of 46 months (range, 12-78), patients had signnificantly better Disabilities of the Arm, Shoulder, and Hand (DASH) scores, and all of them had a score of excellent according to the Büchler criteria and, by final follow-up, were able to resume their preinjury work and sports activities.

Securing of osteotomy

As with any other fracture, different options are available, including plaster immobilization, K-wire fixation, plate-and-screw fixation, and external fixator application. An osteotomy can be left alone only if there is inherent stability at the osteotomy site, which can occur with step-cut osteotomies. Basal osteotomies can be held with K-wires. However, plate-and-screw fixation is preferred for rigid fixation and immediate postoperative mobilization to prevent stiffness and adhesions and thereby improve function.

Timing of osteotomy

The timing of operative intervention is vital, especially in malaligned fractures proceeding to established malunion. If the fracture malalignment is addressed surgically within 10 weeks, then the fracture site can be exposed, the callus can be removed to recreate the original fracture, and the fracture can be managed with appropriate fixation.

When functional loss is predicted from the amount of malalignment at the time of evaluation, there is little value in waiting to perform the correction. However, in cases with milder deformities, it is better to wait to do a corrective osteotomy until the degree of functional loss can be estimated.

Most surgery in the hand is undertaken to promote function. Early mobilization is essential to ensure a good outcome. Delaying motion beyond 3 weeks leads to arthrofibrosis and a poor functional outcome. Optimal surgical treatment should allow adequate postoperative motion, and to achieve a good outcome, patients should be encouraged to move their fingers daily.