Fig. 5.1
(a) Crush injury with TM dislocation, and fractures of the fourth and fifth metacarpals. Initial treatment with percutaneous K-wires, performed at an outside Hospital before transfer to our institution. (b) TM joint ORIF. Dorsal plate in the fourth metacarpal, and laterally applied in the fifth metacarpal, with supplemental cancellous bone graft. (c) Final X-ray
It is difficult to definitively establish the presence of a non-union in a bone of the hand. The radiographic appearance alone is unreliable. The majority of closed hand fractures, without mal-alignment, are solid enough to begin motion at 3 weeks, which is long before union appears on x-ray [1]. Frequently it is difficult to distinguish between delayed and non-union, particularly when there is bone hypertrophy. Deformity and implant failure after operative treatment are, however, reliable indicators of non-union.
In delayed unions with hypertrophic callus formation, fracture lines can be seen radiographically for several months in a fracture that will subsequently heal uneventfully. If there is doubt then a ´wait and see´ policy is probably the best option, with continued splinting and only gentle mobilization. Surgical intervention only being undertaken when conservative treatment has clearly failed.
In contrast, in nascent malaligned fractures [2], our policy is to undertake open reduction and fixation (Fig. 5.2a, b). This approach saves time and often the procedure is easier. Conversely, children have the innate ability to remodel any fracture, the important factors being the skeletal age, the location of the fracture in respect to the growth plate and the amount and plane of malalignment [3]. In addition, in contrast to adults, stiffness is not a major concern in the pediatric population.
Fig. 5.2
(a) Failed percutaneous fixation with K-wires. (b) Secondary ORIF with a plate and a lag screw
Classification
A Metacarpal Malunions
Metacarpal malunions may be classified as either extra-articular or intra-articular.
Extra-articular malunions can be classified into three different patterns:
Rotational malunion: appears after a spiral or oblique shaft fracture, causing a troublesome overlapping of the affected finger over an adjacent finger during flexion (‘scissoring’). Each degree of metacarpal fracture rotation may produce as great as 5° of rotation at the fingertips. Cosmetic deformity is often marked and grip is impaired. Rotational deformities have poor prognosis in children, being the deformity that continues despite growth.
Malunion with angulatory deformity: after a transverse shaft fracture, the pull of the interossei flexes the distal fragment, creating an apex dorsal deformity. This is particularly bothersome in the second and/or third metacarpals, as the index and middle CMC joints have less compensatory mobility than those in the ring and small fingers. Cases with severe angulation results in a dorsal prominence aesthetically displeasing and a prominent head in the palm. There may be compensatory hyperextension at the MCP joint that results in a pseudoclaw deformity when the digit is fully extended. In children, angulatory deformity in the plane of joint motion almost always remodels.
Fractures to the neck of the second to fifth metacarpals are followed by characteristic volar angulation to a variable degree (Fig. 5.3). Because function is acceptable, minor degrees of angulatory malunion can be accepted, up to about 40° in the little finger, and 30° in the other digits [4]. Substantial angulated fractures of the metacarpal neck of the small finger (a so-called boxer’s fracture) often present with a significant cosmetic deformity (sunken knuckle), although rarely, in our experience, palmar projection of the metacarpal head resulting in long term pain or indeed loss of function.
Fig. 5.3
Malunion after fifth metacarpal neck fracture. Disability was minor, and the patient refused surgery
Metacarpal shortening: usually appears after an oblique fracture with incomplete reduction. Loss of knuckle contour is noted, being located more proximal than normal.
A severe shortened malunion occurs usually after an open crush fracture with bone loss. Strauch et al. [5] examined the relationship between shortening of the metacarpal and an inability to fully extend the MCP joint (extensor lag) in a study on cadavers. They observed an average 7° lag for every 2 mm of shortening. They speculated that the fact that this amount of lag is not usually observed clinically, may be related to the capacity of the MCP joint to hyperextend.
Intra-articular malunions have been classified into three types:
Malunited intra-articular fractures of the base of the first metacarpal, which have healed with residual displacement of the joint surface. These cases are prone to develop secondary degenerative change in the mid to long term, although this is unpredictable. In addition, radiographic appearances do not always correlate with the clinical result.
Malunited fracture-dislocations of the CMC joints of the long fingers. Unfortunately, early diagnosis is often missed as a clinical deformity is obscured by swelling on the dorsum hand. In addition, radiographic examination is also often inconclusive, requiring a CT scan to reveal the true nature and severity of the injury. If the fracture is missed, surprisingly in our experience the pain does diminish over 12 months or so, although the patient can be left with stiffness and deformity.
Metacarpal head malunion: usually this occurs after an oblique fracture within the metacarpal head, often in the sagittal plane. Any displacement of the joint surface leading to joint incongruity should be corrected as early as possible. This is also our policy with vertically or horizontally directed fractures in a coronal plane. In skeletally immature patients, subsequent deformity can also be a consequence of failure of normal growth due to an epiphyseal plate injury.
Phalangeal Malunions
Classified into four types:
Rotational malunion: appears after oblique or spiral fractures of the proximal and middle phalanges. If severe, overlapping of the finger occurs whilst making a fist.
Angulatory deformity: unstable shaft fractures of the proximal phalanx, typically present with angulation convex in a palmar direction. More rarely, lateral angulation can occur. Some deformities are mixed or multiplanar. Any angulatory deformity after a fracture of the middle phalanx is dependent upon the nature of the injury and location of the fracture. Distal fractures commonly show volar angulation, believed to be due to the strong pull of the flexor sublimis tendon on the proximal fragment, whilst the distal fragment is extended by the terminal extensor tendon. In a metaphyseal fracture, located proximal to the superficialis tendon insertion, the proximal fragment is pulled into extension through the action of the central extensor tendon. However, any deformity in displaced fractures is probably more related to the force and direction of the initial trauma, rather than any subsequent tendon pull.
Articular malunion: the most frequent cause is a condylar fracture of the proximal phalanx. Weiss and Hastings [6] established an x-ray classification system, with four main patterns:
type I: involved an oblique palmar pattern. The fracture line extends from the proximal metaphyseal flare of the distal aspect of the proximal phalanx, to the intercondylar sulcus at the distal articular surface. The small fragment lies palmar to the phalangeal shaft. This accounted for almost 80 % of condylar fractures, with the little finger the most commonly involved.
type II: involved a long oblique fracture line, with the plane of the fracture sagitally oriented.
type III: represents a dorsal coronal fracture, due to hyperflexion of the PIP joint.
type IV: a small palmar coronal fragment, is produced by hyperextension of the PIP joint.
Being highly unstable fractures, they are frequently misdiagnosed and/or inadequately treated (Fig. 5.4). Proper reduction with manipulation is impossible. The fractured condyle often suffers further displacement with significant angulatory deformity and joint incongruity, frequently only discovered several weeks later. A malunited unicondylar fracture results in very considerable disability and is challenging to manage surgically. Preoperative evaluation is made by PA projection (to assess articular step-off) and lateral (to see palmar displacement of the condyle) and oblique radiographs to identify the fracture line.
Fig. 5.4
Unicondylar displaced fracture, which was not properly treated, causing pain, deformity and limitation of flexion
Clinical Pearl
In unicondylar proximal phalangeal unstable fractures, oblique radiographs are mandatory to assess displacement. Reduction must be anatomic. Fixation with two screws is preferred, to allow early motion.
Malunion after fractures involving the condyles of the middle phalanx appears less frequently, especially after unicondylar fractures. In our series bicondylar fractures are more frequent. In these cases reconstruction is often impossible and a secondary DIP joint fusion may be necessary.
Phalangeal shortening severe enough to be symptomatic is a rare complication. Vahey et al. [7] performed a cadaver study to determine the effect of shortening and angulation of the proximal phalanx on extensor lag at the PIP joint. However, a linear relationship was observed between the lag and shortening (12° of lag/1 mm of shortening) and increased angulation was seen to result in a proportionately increased lag. The severity of any associate soft tissue injury is more significant for the outcome than bone shortening.
Surgical Techniques in Malunions
Surgeons have long debated whether it is preferable to correct the malunion at the site of the fracture, or to perform a corrective procedure at a separate site. Osteotomy, at the site of the original fracture, has the greatest potential for correction of the deformity and subsequent contracture, although it also has the potential for producing adhesions. Extrafocal osteotomy is perhaps a better option after a complex fracture, allowing the surgeon to work with more healthy bone. Each case must be individualized and preoperative planning is crucial.
Surgical Techniques in Metacarpal Malunions
Extra-Articular Rotational Malunion
One option is the corrective step-cut osteotomy described by Manktelow and Mahoney [8]. Two hemitransverse osteotomies on opposite sides of the metacarpal diaphysis are produced and connected by a dorsal longitudinal cut. A longitudinal strip of dorsal cortex is then removed (it is important to remember that 1.3 mm of dorsal bone results in 1 cm of fingertip correction). Afterwards a longitudinal fracture is created in the volar diaphyseal surface. Bone fixation is undertaken by several lag screws. This osteotomy provides a large bone surface to promote healing, although it is technically a demanding procedure.
Osteotomy of the metaphysis is easier technically. Stern et al. [9] recommends placing a longitudinal mark on the metaphysis with an osteotome. The osteotomy is made with an oscillating saw, perpendicular to the mark. Afterwards a K-wire, inserted perpendicular to the distal shaft, acts as a ´joystick´ to correct rotation of the distal fragment. Fixation is accomplished with multiple K-wires, or preferably with a plate and screws.
Extra-Articular Malunion with Dorsal Angulation
A closing wedge osteotomy at the level of the fracture is a less demanding procedure technically. If possible, consider an incomplete osteotomy preserving the intact opposite cortex, or at least the volar periosteum allowing it to act as a hinge.
A triangular wedge is removed and a plate and screws are applied to allow good fixation and early motion. Yong et al. [10] reported a double osteotomy, proximal and distal to the apex of the dorsal angulation, obtaining a trapezoidal segment of bone, which is rotated and re-inserted as a bone graft, again being fixed with a plate. If there is associated significant metacarpal shortening, an opening wedge osteotomy using a trapezoid interpositional iliac crest bone graft is undertaken, again fixed with a dorsal plate to allow early motion.
Metacarpal Shortening
If this is less than 1 cm and without angular deformity, it usually does not require correction. In extreme cases however, an opening wedge osteotomy with interposition of a structural bone graft, usually from the iliac crest, can be undertaken with a dorsal plate fixation. A gradual distraction with an external fixator is also an option, although associated soft tissue contracture may make this difficult.
Surgery after a high energy injury is more difficult and requires awareness with regard to local blood supply, concomitant nerve lesions and tendon injuries. In complex open fractures with bone loss, following thorough debridement provisional osseous stability is achieved with spacer wires, supplemented with external fixation. Rarely, skin coverage is attained in the emergency procedure and is usually performed over the next days when the wound is surgically clean.
For most open fractures with bone loss, a single block of corticocancellous graft harvested from the iliac crest and fashioned to fit into the defect, will provide the definitive bone reconstruction. In some more severe cases, however, a free vascular bone graft may be required.
Intra-Articular Malunion
The treatment of displaced intra-articular fractures of the base of the first metacarpal has improved with the use of fixation (K wires, screws and plates or mini external fixators), with the additional use of bone graft or bone substitutes as appropriate. This surgery, however, can be difficult and does not always have a favourable outcome. It is however worth attempting in young patients. To treat malunited symptomatic Bennett´s fracture, Giachino [11] reported removal of a block of bone of the radial aspect of the first metacarpal, big enough to correct the articular step-off, but leaving a radial basal fragment big enough to be fixed with two screws to the ulnar articular fragment. After complex articular fractures with residual depressed fragments, secondary reconstruction is rendered more difficult. In more long standing cases, if pain persists after initial conservative treatment, fusion of the TM joint is recommended, or alternatively in low demand patients, arthroplasty may be an option.
Fracture-dislocations of the CMC joints of the long fingers present in various guises. Often residual malunion with persistent CMC subluxation, particularly of the index and middle fingers, can be well tolerated. Chronic subluxation of the fourth and fifth metacarpals, however, is sometimes symptomatic and requires treatment.
In the early cases with a malunion of less than 8 weeks, the best option is an intra-articular corrective osteotomy through the fracture site. This should be supplemented by internal fixation. The aim of surgery is not only to achieve a congruent surface, but allow motion to begin as early as possible. Whilst K-wire fixation is an option, mini-cannulated screws may be more optimal. In the long term normal joint motion is rarely achieved, but reasonable grip and pain relief can be attained.
If congruent reduction is not possible, or there is severe cartilage damage, options include either arthrodesis, excision arthroplasty or silastic interposition. Trimming off any bony protrudement is also recommended.
Surgical Techniques in Phalangeal Malunions
A dorsal approach is usually preferred, preserving veins in the skin flaps and splitting the extensor tendon to expose the proximal phalanx. If possible, the tendon and the periosteum are elevated in separate layers. If tendon adhesions are present, tenolysis and /or capsulotomy is performed. In recent cases, especially in multiplanar deformities, we prefer to recreate the original fracture line by mobilizing the fracture callus. Fixation has been improved with the new low profile titanium plates, easy to contour and even cut and available in a variety of configurations. The plate is applied on lateral surface when possible. Also self-tapping mini-screws are useful to fix step-cut osteotomies, which again allows early motion.
In mature malunions, different methods of treatment have been reported.
Rotational Malunion
The correction of rotational deformity is particularly difficult to undertake. Weckesser [12] recommended an osteotomy at the base of the corresponding metacarpal to correct this rotational deformity. He undertook fixation with a longitudinal K-wire and two horizontal K-wires through the distal fragment and adjacent metacarpal. Bindra and Burke [13] also described this procedure, this time securing the osteotomy by plate fixation.
This type of surgery is limited by the deep transverse metacarpal ligaments, which restrict rotation. Gross and Gelberman [14] undertook experiments on cadavers to determine the maximal rotational correction of a phalangeal malunion that can be achieved with a metacarpal osteotomy. It was possible to correct up to 18° of malrotation in the index, long and ring fingers and up to 30° of malrotation in the small finger. Releasing this ligament may result in loss of the transverse palmar arch and instability of the MCP joint and is therefore not recommended.
Angulatory Deformity
Volar angulation is difficult to detect when the fracture is at the base of the proximal phalanx, because it is almost always superimposed on the other phalanges on the lateral film. If, however, there is enough malalignment to predict functional loss, then surgery is undertaken. Our preferred technique is to recreate the original fracture line and undertake fixation with either cross K wires or a mini plate.
In mature malunion, an initial period of observation, particularly of the smaller deformity, is recommended to quantify the degree of dysfunction. If the latter is severe, a closing wedge osteotomy at the site of the malunion is performed, leaving, if possible, the opposite cortex intact, the latter acting as a hinge. Fixation is again performed with a mini-plate if proximal fragment is big enough.
For patients with angulatory deformity in the frontal plane, despite shortening the digit, closing corrective osteotomy leaving the opposite cortex intact, is the easiest procedure. Fixation is carried out using a mini-plate if the soft tissues are in a satisfactory condition and with 2 K-wires if they are not. Trumble and Gilbert [15] reported a practical way to design the osteotomy. Lines were drawn parallel to the shaft of the phalanx distal and proximal to the malunion. Afterwards, perpendicular lines are drawn at the location where previous lines intersect at the malunion, outlining in this way the wedge of bone to be removed.
The plate is initially secured to the proximal half of the proximal phalanx, although subsequently only one screw is maintained so the plate can be rotated out of the way, allowing the osteotomy to be undertaken. We would recommend using a power saw with a thin blade and saline irrigation to limit thermal damage. Afterwards the finger is rotated until it is parallel to other digits, with the PIP joint in 90° of flexion. Finally the plate is then secured to the distal fragment.
An opening wedge osteotomy, using a corticocancellous bone graft, requires a lateral plate fixation. This is, however, a difficult procedure and in our opinion very rarely indicated. Additional tenolysis and capsulotomy is carried out, when necessary.
Displaced neck fractures of the phalanges may be missed unless a true lateral radiograph is obtained, showing the rotated head fragment. If some bone contact is maintained, usually union is achieved, especially in young patients. As there is no epiphysis at the distal end of the phalanx, spontaneous remodeling of residual angulation is limited and only significant in young patients [16, 17]. If, however, there is a volar spike present, this can limit PIP flexion. Surgery to remove this spike, often termed osteoctomy or cheilectomy (Fig. 5.5a–c), restores the articular surface and can result in an improvement in flexion, particularly in children [18].
