Distal Radius Malunion



Fig. 7.1
The different patterns of carpal response to dorsal tilt. Both patients are young and have a similar degree of deformity. In (a) the carpus has subluxed as a whole dorsally. In (b) a zigzag collapse has occurred (Copyright Dr. Piñal 2011)



Park et al. [7] have further subdivided this DISI type pattern of “compensation” into two subtypes: A type I, in which the deformity is correctable after osteotomy and a type II (or fixed), in which the osteotomy will have no or minimal effect. It seems that the latter group may, in fact, be patients whom, in addition to having an extra-articular malunion, have an unrecognized scapho-lunate dissociation. Stiffening of the wrist ligaments in the older patient has also been implicated as responsible for the fixed nature of the type II. Prognosis after osteotomy for the type II group is considerably worse [8].

Loss of the volar tilt of the radius also has dramatic consequences on the ulno-carpal and distal radio-ulnar joint mechanics and load distribution. The load bone, by the head of the ulna, will increase by 50 % with a dorsal tilt of only 10° and by 67 % at 45° [2, 3]. Furthermore, the congruency and contact areas at the sigmoid fossa will be changed, thus creating a pre-arthrotic state and diminishing forearm rotation [9]. Besides this, Pogue et al. showed that shortening beyond 4 mm, 0° radial inclination, 30° of palmar inclination, or 15° of dorsal inclination could not be attainable unless the styloid were fractured, or the TFC were detached. This study gave biomechanical support to the frequent finding of DRUJ instability in the setting of malunions [10].

Symptoms on the ulnar side of the wrist and altered joint biomechanics will further worsen as a consequence of shortening of the radius that frequently accompanies radius malunion. The TFC will be locked as a result of shortening [3, 9, 11] and the load transmitted through the head of the ulna will be increased exponentially [3, 12]. In a series of experiments, Short et al. [12] demonstrated that only 2.5 mm of ulnar lengthening (radius shortening) increases the load borne by the head of the ulna from the normal 21% to as much as 42%, as the load through the radius decreases and concentrates dorsally.

Loss of radial inclination has a debatable effect. Radial inclination losses of up to 0° have minimal impact and, even then, only a slight decrease in grip strength has been reported. Malrotations in the axial plane [13], although responsible for lack of pronation-supination (particularly in Smith type malunions), are self-corrected at the time of surgery if a volar preformatted plate is used.

Intra-articular malunions have a much worse prognosis, due to the rapid development of secondary osteoarthrosis. Baratz et al. and Wagner et al. [14, 15] have demonstrated that step-offs at the radio-carpal joint cause abnormal concentrations at the edges of the step-offs (up to eight times the basal value) and abnormal motion of the corresponding carpal bone. Loss of cartilage will occur early in this setting and osteoarthritis will be the end result [16].



Indications


There is no universally accepted definition of distal radius extraarticular malunion to guide the treating surgeon as to when and how to treat. Acceptable limits of the three key radiographic parameters (volar tilt, radial inclination and ulnar variance) have not been even clarified. Although most authors use the contralateral wrist as a reference, Schuind et al. [17] reported that the normal wrist does not provide a better reference than normal values obtained from a database. Thus, Prommersberger et al. [18] defined the normal limits as within one standard deviation of the mean values of the general population: 8.5–15.5° for volar tilt, 21.5–26.5° for radial inclination and −2.5 to 0.5 mm for ulnar variance. To complicate things further, in the decision making process some patients (particularly older) might have severe deformities with minimal symptoms, while others (particularly young and active) with minimal deformities complain bitterly of pain or limitations. To summarize, in my view any patient who has lost any of the three key parameters of radius alignment and has pain and/or decreased range of motion and/or instability (at the radiocarpal, midcarpal or distal radio-ulnar joints) is a candidate for surgery provided he/she is fit for the operation. Prearthrotic conditions, such as dorsal tilt of more than 20° [25], is on itself an indication in a young-active individual.

Furthermore surgery is no longer contraindicated in older individuals with osteoporosis, provided rigid volar locking plates are used. Previous reflex sympathetic dystrophy is also no longer a contra-indication, provided measures are taken to prevent recurrence at subsequent surgery. The involvement of a pain management consultant is strongly recommended.

As for the timing of surgery, there is general agreement that an intra-articular malunion should be undertaken as soon as possible, to avoid irreversible cartilage damage. In extra-articular malunions, some surgeons prefer to wait until tissue equilibrium has been reached and maximal function has been regained. Jupiter and Ring [19], in a comparative study, concluded that early surgery provided earlier return to work, less total disability time and less need for bone graft. The final functional results were equally good for both early or late osteotomy groups.


Surgical Techniques and Rehabilitation


Procedures to the radius, the ulna or both may be needed to treat distal radius malunion. To avoid confusion however, in this chapter they will be considered individually, although the surgeon should keep in mind the number of procedures that may have to be undertaken during the operation. Except in cases where there is no (or minimal) radial deformity (where an ulnar procedure is all that it is required) the operation always follows three steps;

1.

a radial osteotomy,

 

2.

an ulnar sided procedure to address impaction,

 

3.

re-exploration of the ulnar side (including an arthroscopy!) to assess and treat DRUJ instability.

 


Dorsal Angulated Malunion


Simply speaking there are two ways of repositioning the dorsally tilted radius: a dorsal opening wedge, or a volar closing wedge. In the latter, further shortening of the radius obliges one to undertake a concomitant ulnar procedure to restore normal ulna variance. It is also important to remember that, whilst by definition all fractures in this group have the distal radial articular surface tilted dorsally, not all Colles’s type malunions will have concomitant radius shortening. True shortening will occur only when there has been volar metaphyseal comminution, or when the continuity of the volar cortex has been lost, due to dorsal translation of the distal fragment. In many of the dorsally tilted malunions however, the volar cortex acts as a hinge point at the fracture line and the distal fragment rotates, but does not translate. This occurs if there is only dorsal comminution: the distal fragment, unsupported dorsally, pivots on the volar cortex, slowly rotating in the cast [20], or when the reduction was insufficient from the beginning. This represents what we have named as a “sagittal rotational malunion”, where there is no shortening despite the appearance on a posterior–anterior radiographic view (Fig. 7.2) [21].

A328677_1_En_7_Fig2_HTML.jpg


Fig. 7.2
Malunited distal radius fracture with true dorsal tilting and apparent shortening of the radius. (a) The sclerotic rim appears to show a positive ulnar variance, and the dorsal tilt of the distal radius (b). (c) The contour of the distal radius has been highlighted by dots, it can be seen that volar rim of the radius (V) is actually distal to the head of the ulna, although the dorsal rim (D) is proximal. (d) On the same P–A view as (a), the volar lip (with dots) is clearly distal to the head of the ulna confirming the inaccuracy of the variance measured in (a). A fine grey line has been drawn tangentially to the ulnar dome across all the radiograms. A fine black line marks the volar rim of the radius (From del Piñal et al. [21] with permission)

Such a sagittal rotational malunion can, however, be recognised on the lateral radiograph, by the “preservation” of the volar cortex and by having the anterior rim of the radius longer (more distal) than the head of the ulna, confirming the absence of shortening (Fig. 7.3a). This distinction is important with regard to management; a pure sagittal malrotation will respond to a much simpler de-rotational osteotomy. Whilst if there has been shortening it will need a more complex tri-dimensional reconstruction or a Wada procedure (see below).

A328677_1_En_7_Fig3_HTML.jpg


Fig. 7.3
Pure sagittal malrotation: diagnostic pointers, planning and execution (same case as in Fig. 7.1). (a) A clear hinge point corresponding to the original fracture line can be seen (arrow), attesting to preservation of the volar cortex length. The distal volar rim can be seen distal to the head of the ulna confirming the ulna minus variance (stippled in black). (b) The hinge point will be used as the rotation point of the distal fragment. (c) Pure rotation on the fulcrum will correct dorsal tilting preserving the radial length. (d) The result on this patient. A fine grey line has been drawn tangentially to the ulnar dome across all the radiographs. A fine black line marks the volar rim of the radius (From del Piñal et al. [21] with permission)

When true shortening exists, the Fernandez’s method [8] of preoperative planning using tracing paper on the deformed side and transporting it to the healthy side in order to give a three-dimensional model of the bone graft is recommended (Fig. 7.4). Although Fernandez’s method is somewhat inexact as compared to computer-generated models [22, 23], it is of an enormous help at the time of surgery and technique accesible to all.

A328677_1_En_7_Fig4_HTML.gif


Fig. 7.4
Planning of the correction as advocated by Fernández. Top left demonstrates the K-wire placement to intraoperatively reference the correction of the dorsal tilt. Bottom left view shows the sagittal correction after the osteotomy with resultant dorsal bone gap. Top right, precorrection loss of radial inclination and radial shortening. Bottom right, postcorrection alignment demonstrates that the cortex is opened more on the dorsal radial than the dorsal ulnar side (In Ref. [8] with permission from the Journal of Bone and Joint Surgery)


Opening Wedge Osteotomy- Volar Approach


Whether there is pure malrotation in the sagittal plane, or a combination with shortening or loss of radial tilt, I always use a volar approach as initially described by Lanz [24]. The time honoured dorsal approach, championed by Diego Fernández (osteotomy, cortico-cancellous interpositional bone graft and dorsal plating) [8], although compared to the former, is an easier technique, has the major drawback of requiring a plate to be applied on the dorsal surface. The latter runs an increased risk of extensor tendon damage. In addition, a second operation for plate removal is more likely.

Conversely, plating volarly is more technically demanding, as it allows no alterations once the plate is fixed distally. On the other hand, it rarely requires plate removal, as tendinitis is unusual (provided the appropriate length of screws is used). The initial problems with Lanz’s technique, related to the implant size and the lack of stability of the construct when length was also corrected, have been overcome with modern fixed-angle plates. As a matter of fact, the exact application of these plates to the malunited epiphysis will automatically correct any malunion. Furthermore, the stability provided by the plate allows immediate rehabilitation, without the need of structural bone graft [25]. Last but by no means least, placement of the plate volarly will spontaneously correct any malrotation of the distal fragment in the axial plane.

Again when planning the procedure we would recommend a technique described by Fernandez [8]. Measurements are taken from the lateral radiographs. The key point is to fix the distal component of the plate, forming an angle (“correction” angle) with the diaphysis equal to the preoperative measured dorsiflexion plus 5°, in order to achieve some physiologic palmar tilt (Fig. 7.5).

A328677_1_En_7_Fig5_HTML.jpg


Fig. 7.5
(a) Correct placement of the plate can be assured intraoperatively by fluoroscopy when the stem of the plate creates an angle with the diaphysis of the same amount as (plus 5º) the dorsal tilt plus 5° (to restore the volar tilt). (b) In this setting “automatic” correction of the deformity will occur (Copyright Dr. Piñal 2011)

The operation is performed under axillary block, on an outpatient basis. The arm was exsanguinated and a tourniquet applied. Bone from the olecranon is harvested through a 2.5 cm transverse incision. The cavity is then filled with Surgicel® and the wound closed in a single layer, using a 3/0 subcuticular nylon.

Access to the malunion site is through a 6–8 cm incision, radial to the flexor carpi radialis sheath (FCR), with a 10 mm radially directed back cut at the proximal wrist crease. By dissecting with a knife on the radial aspect of the FCR sheath, the sheath can usually be preserved intact, but, more importantly, the radial artery will stay safely lateral. The space between the FCR and radial vessels is developed. A large constant branch from the radial vessels to the radial aspect of the pronator quadratus should be identified and coagulated. This muscle is then sharply elevated subperiostically and reflected ulnarly. Proximally, some fibres of the flexor pollicis longus are reflected ulnarly. This will expose the malunion site, the distal epiphysis and the radial shaft. Dissection now proceeds on the dorsum of the radius, going superficial to the brachioradialis, which is left undisturbed, except in cases of major radius shortening. The whole layer of thickened-scarred periosteum is elevated on block and then divided by making several transverse cuts, proximal to the extensor tendon compartments, until the tendons themselves are exposed. Unless this is done, proper reduction of the epiphyseal fragment would not be attainable, as this scarred tissue acts as a check-rein to volar tilting of the distal fragment.

At this moment the fixation plate is applied volarly, prior to the osteotomy, as recommended by Lanz [18, 24]. The transverse part of the plate is placed as distally as possible and always distal to the hinge point of the malunion. Guide K-wires are invaluable to ascertain that the distal pegs will be subchondral, as this will guarantee a strong hold. If the surgeon is satisfied with the fluoroscopy image, all the distal screws and pegs are inserted. As mentioned previously, at the end of this part of the operation, the plate should form an angle with the radial shaft (correction angle) equivalent to the amendment needed in the sagittal plane. To avoid the loss of any volar cortical bone by the cut of the saw, the osteotomy is performed using a 1 mm diameter K-wire. A series of perforations parallel to the articular surface, to the dorsal cortex, are made along the exact hinge point of the malunion (Fig. 7.6). Once the osteotomy is completed, the surgeon applies force dorsally to the distal-radius and plate to produce an osteoclasis of the weakened volar cortex. Quite frequently several attempts are needed and in some cases an oscillating saw is required to cut the very sturdy medial (ulnar) cortex. The distal-radius/plate block is then reduced to the shaft of the radius, by pushing volarly with the fingers on the distal fragment, as in a closed Colles’ reduction. The use of a lamina spreader to distract the collapsed dorsal space greatly helps achieve reduction. Other manoeuvres, such as the use of bone clamps to bring the stem of the plate to the shaft of the radius, are to be avoided as this may cause the screws to be pulled out of the bone. Once the plate adapts to the volar shaft cortex without undue force, it is held temporarily by two bone clamps. It is now critical to perfectly reduce the volar cortex, as otherwise shortening and incomplete volar tilt correction will ensue. Once this has been checked radiologically the rest of the screws are inserted and a bone graft applied. Thereafter pronator quadratus is closed, if possible, over the plate, by preplacing three resorbable stitches and tightening them in pronation. The skin is closed with subcuticular 3/0 nylon. In every case a standard exploratory dry arthroscopy follows the osteotomy [26]. Synovectomy, soft tissue procedures and/or ulnar styloid excision is undertaken as required (Fig. 7.7) (see “Ulnar side procedures” later).

A328677_1_En_7_Fig6_HTML.jpg


Fig. 7.6
The osteotomy is being performed with a 1 mm k-wire. Notice that the plate stands out of the diaphysis (correction angle) (From del Piñal et al. [21] with permission)


A328677_1_En_7_Fig7a_HTML.jpgA328677_1_En_7_Fig7b_HTML.jpgA328677_1_En_7_Fig7c_HTML.jpgA328677_1_En_7_Fig7d_HTML.jpg


Fig. 7.7
(a, b) Despite the severity of the deformity and the apparent shortening of the radius the patient has a pure malrotation in the sagittal plane, without any shortening of the radius: notice the hinge point and the position of the volar rim distal to the head of the ulna in the lateral. (c, d) Pure derotational osteotomy fully corrects the deformity. (e, f) Lack of flexion is the most prominent complaint in most Colles’ type malunion. (gj) Final range of motion. Notice the improvement in flexion (Copyright Dr. Piñal 2011)

A bandage and volar splint are applied and then the tourniquet is released, maintaining some pressure over the surgical area for 5 min for haemostasis. At the first preoperative visit, 24–48 h later, a removable splint is applied, encouraging self-directed active range of motion exercises. After the 4th-6th week patients are weaned off the splint. No formal therapy is prescribed. Protection of the elbow for 4–6 weeks with skateboard splints is also recommended.

In cases of true concomitant shortening (and angulation) the technique is slightly modified or Wada’s operation (see next section) is undertaken. The dorsal tilt is first corrected, with the plate inserted distally and then reduced to the shaft of the radius. With the help of a laminar spreader at the osteotomy site, the radius is distracted as required. Then, the screws are inserted into the longitudinal stem of the plate, to lock it. It is important, when shortening exists, to step-cut the brachioradialis as otherwise it will limit correction. The tails of the Z-plastied tendon are sutured at the end of the operation. The appropriate graft size is interposed; the graft itself, typically being cortico-cancellous, can be taken from the iliac crest. Modern plates allow the insertion of cancellous bone graft or even bone substitutes. It is, however, quite difficult to correct more than 10–15 mm of radial shortening by an open wedge procedure as proposed previously [8, 27] (see next section). Finally, severe shortening of the radius, more than 3 cm, requires distraction of the radius.


Closing Wedge Osteotomy (Wada’s Procedure)


To avoid the need for bone graft and the risk of non-union, Posner and Ambrose [28] proposed a volar closing wedge osteotomy of the radius, combined with a Darrach procedure to address the distal radio-ulnar joint. The operation is less involved for the patient, as no bone graft is required and for fixation, the better-tolerated volar plate can be used. Despite good results reported at 5 years in a relatively young patient group (40-y-o), most hand surgeons would consider sacrificing a healthy/preservable distal radio-ulnar joint as a disservice to the patient. By the same token, however, when the DRUJ is irreversibly damaged, there is not much point in restoring the radial length. In these cases a Posner-Ambrose procedure, or a closing wedge radial osteotomy combined with a Sauvé-Kapandji, or an ulnar head replacement, are the options of choice.

Wada et al. in 2004 [29] popularized the concept of combining a closing wedge osteotomy of the radius and an open ulnar shortening, rather than a destructive procedure on the ulnar side. Initially they recommend it for the elderly or less demanding patients [29]. However, due to their good results they have now extended their indications to all ages [30].

Only gold members can continue reading. Log In or Register to continue

Stay updated, free articles. Join our Telegram channel

May 22, 2017 | Posted by in ORTHOPEDIC | Comments Off on Distal Radius Malunion

Full access? Get Clinical Tree

Get Clinical Tree app for offline access