The forearm should be considered as a joint consisting of two long bones and three ligamentous restraints: the an- nular ligament complex, the interosseous membrane (IOM), and the triangular fibrocartilage complex (TFCC).
There are two articular components as well: the proximal (PRUJs) and distal radioulnar joints (DRUJs), which permit rotation of the radius on a relatively fixed ulnar axis.
If the forearm is now looked upon as a joint, diaphy- seal fractures should be considered intraarticular and therefore deserve – as in any other fracture that disrupts an articular surface – accurate anatomic reduction to guarantee full restoration of function. This same principle should be taken into consideration for the surgical recon- struction of nonunited and malunited forearm fractures.
Although open reduction and compression plate fixa- tion of forearm fractures invariably restores anatomy and function with a relatively low rate of complica- tions,1–5 surgical reconstruction of forearm nonunions and malunions represents a more difficult challenge in which despite achieving bony union, correcting defor- mity, and relieving pain, complete and symmetrical restoration of forearm rotation is difficult to obtain, but may be certainly improved to a reasonable functional arc of pronation and supination.
This is due to the frequent concomitant derangement of the PRUJS and DRUJs as well as the IOM commonly associated with the bony deformity of the nonunited or malunited forearm bones. In both scenarios, symmetric shortening of both bones may not alter the congruity of the PRUJ or the DRUJ, provided there is no significant associated angular deformity. Conversely, shortening of a single fore- arm bone with or without angular deformity will automati- cally affect the articular anatomic relationships of either the PRUJ or DRUJ. Loss of the physiological bow of the radius is responsible for limited pronation, whereas reduction of the interosseous space associated with angular or ad latus (translation) deformity leads to secondary contracture of the IOM and decreases forearm rotation.
Posttraumatic radioulnar synostosis is a less frequent complication, but its management, although currently well standardized, does not exclude recurrence in pa- tients with special risk factors.
In this chapter, we describe the current principles of management of both simple and complex diaphyseal
forearm nonunions and malunions in adults, and present treatment recommendations for both primary and recur- rent radioulnar synostosis.
Finally, any of the above can be aggravated by infection, soft tissue defects, soft tissue contracture, neurovascular deficit, and stiffness of the neighboring joints (elbow and wrist).
Treatment
The goals of treatment must extend beyond obtaining bony union to ensure anatomic restoration of skeletal alignment and both congruity and stability of the PRUJs and DRUJs.
Preoperative assessment should include a careful clinical examination of the whole upper extremity to document the residual forearm function and that of the neighboring joints, the soft tissue condition, and the neurovascular sta- tus. Laboratory studies including an electromyogram for nerve lesions or aspiration and cultures in infected cases are routinely performed. For the radiographic assessment, comparative x-rays of both forearms including the elbow and wrist joints are considered essential for the preopera- tive planning and correction of deformity or shortening associated with the nonunion. Most of the simple, straight- forward cases do not need additional imaging. Computed tomography (CT) may be helpful to rule out the presence of sequestrae in infected cases, and assess rotatory deformity and congruity of the DRUJ. Magnetic resonance imaging is reserved to evaluate additional soft tissue lesions such as the TFCC, the IOM, and muscle defects. Arteriograms are useful to document the patency of the vascular axes in nonunions following severe high-energy trauma, particu- larly when planning microvascular reconstruction of large bony defects.
Surgical Treatment
General Principles
Disregarding the localization of the forearm nonunion, hypertrophic well-vascularized nonunions are managed with decortication of the callus and stable plate fixation, whereas atrophic nonunions need rigid fixation and au- tologous bone grafting. These principles of nonunion management advocated by Müller7and Weber and Çech6 over 40 years ago have stood the test of time and are asso- ciated with a high success rate.
Small diaphyseal defects may be bridged with a struc- tural corticocancellous iliac graft, fixed to the plate. In larger diaphyseal bone defects up to 10 cm, in which a cir- cumferential well-vascularized soft tissue bed is present, long bridging plates and morcellized iliac bone grafts are the procedure of choice because diaphyseal stability and skeletal continuity, length, and alignment are readily achieved along with rapid functional recovery.8
Vascularized bone grafts are reserved for those situa- tions of large defects in which conventional bone graft- ing procedures have failed and in those cases with poor
vascularized bed and massive scarring as in chronically infected cases or in situations with composite soft tissue and skeletal defects following mutilating injuries.9,10
Creation of a one-bone forearm for the treatment of large diaphyseal defects (most commonly in the ulna) is a valid alternative,11–13but skeletal continuity is restored at the expense of loss of forearm rotation. For this reason this modality remains, in our view, the ultimate salvage procedure. Other valid alternatives of nonunion manage- ment such as electrical stimulation,14,15the use of bone morphogenic protein,16,17or the use of the Ilizarov tech- nique18will not be discussed because we do not routinely use these options.
Tactics Approaches
Our preferred surgical exposure for the radius is the exten- sile approach described by Henry,19 in which the whole bone from the radial head to the wrist joint can be exposed medially to the brachioradialis on the volar aspect of the forearm. In the proximal third the major advantage is that both the deep and superficial branches of the radial nerve can be protected as the supinator muscle is detached from the proximal shaft. Extension of the incision proximally to the elbow flexion crease further permits exposure of the anterior capsule of the elbow joint, particularly the lateral compartment and the PRUJ. In the midshaft area the inser- tion of the pronator teres is well visualized, and the inser- tion of the central part of the IOM can be exposed at this level. In the distal point the radius may be widely exposed partially elevating the insertion of the flexor pollicis longus muscle and further distally the pronator quadratus.
The whole of the ulna is exposed with a longitudinal incision over its subcutaneous border between the ex- tensor and flexor carpi ulnaris (FCU) muscles. If expo- sure of the DRUJ is needed, the incision may be extended distally by swinging it dorsally over the ulnar head at the neck level ending at the junction of the fourth and fifth carpometacarpal joints. In this manner the superfi- cial branch of the ulnar nerve remains safely in the me- dial subcutaneous flap. The PRUJ is exposed through a posterolateral approach between the anconeus and ex- tensor carpi ulnaris. (ECU) If scars of previous surgery are present, usually these are utilized to avoid additional soft tissue disruption and iatrogenic devascularization.
Preparation, Reduction, Fixation, and Bone Grafting
Hypertrophic nonunions require minimal exposure of the nonunion site to preserve the well-vascularized a callus on both fragments. Limited decortication at the surface of plate application is all that is needed. Because these
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nonunions are generally elastic, the associated deformity is usually corrected by carefully molding the plate to the nor- mal anatomy of the shaft segment. The plate is securely fixed to the proximal fragment and deformity correction is gradually obtained with strategic use of the compression device and bone clamps applied to the distal fragment. This works very nicely when the plate comes to lie on the con- vexity of the angulation, acting as a tension band implant. If the convexity of the angulation faces the opposite bone re- ducing the interosseous space, associated IOM release is mandatory. The prebent plate is then fixed in a bridging mode to which one screw is inserted in the most proximal and one in the most distal plate hole. Thereafter using Ver- brugge bone clamps the ununited bone ends are approxi- mated to the plate, thus recreating the interosseous space.6 Following reduction, axial compression can be achieved with eccentric introduction of screws of a dynamic com- pression (DC) plate. Molding of the plate with the appropriate curvature is particularly important in the midshaft area of the radius, whereas less plate bending is needed in the proximal and distal thirds. For the ulna, being practically a straight long bone, a slight bend at the nonunion site is helpful to obtain compression at the oppo- site cortex as in acute fracture fixation.
Atrophic nonunions require a more careful preparation of the site including resection of necrotic areas to bleeding bone, as well as devitalized intermediate fragments. The obliterated medullary canal on both ends is routinely opened with an awl or a drill bit that accommodates to its diameter. Although relatively small defects created after débridement of a bone forearm nonunion may be stabi- lized with plates creating a symmetric skeletal shortening, whenever possible we prefer to maintain length using bridging plates and interpositional bone grafting. This is particularly important in the treatment of large defects of one bone, while the opposite bone is intact.
If the radius presents with a pseudoarthrotic defect, there is severe radial deviation and shortening of the distal fragment, as well as disruption of the DRUJ with a positive ulnar variance, which equals the amount of radial shortening (Fig. 18–1). A pronatory rotational deformity is frequently present as well as palmar displacement of the distal fragment.
Because these chronic nonunions are invariably associ- ated with soft tissue contracture, restoration of length and realignment of the DRUJ can be obtained with a com- bination of soft tissue release and intraoperative tempo- rary distraction. Soft tissue release includes resection of
Figure 18–1 (A,B) Large defect nonunion of the distal third of the ra- dius. Notice distal radioulnar joint disruptions, severe shortening, and radial deviation of the distal fragment. Middle: Intraoperative roentgenograms with the distractor in place. Notice realignment of the
distal radioulnar joint. (C,D)Radiographs at 12 months following volar bridge plating and autologous morcellized iliac crest cancellous bone grafting. Notice cortical remodeling of the interposed graft.
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Solutions for Complex Upper Extremity Traumascarred nonviable tissue surrounding the nonunion area, detachment and partial resection of the contracted IOM, and subperiosteal detachment of the brachioradialis ten- don from the distal radius. If severe contracture of the DRUJ is present, release of the pronator quadratus and re- section of the volar DRUJ capsule are recommended.
Intraoperative progressive distraction of the nonunion is achieved with the use of the AO femoral distractor,20plac- ing one 4.5-mm Schanz pin into each radial fragment. Dis- traction should be performed slowly over a period of 30 minutes (Fig. 18–1). Visual control of the median nerve to avoid excessive sudden tension is important, although one stage restoration of posttraumatic skeletal shortening up to 2.5 to 3 cm is usually not associated with neu- rapraxia. However, this may occur if the peripheral nerve is tethered and adherent to scarred tissue. Therefore, inspec- tion of the nerve and neurolysis should be performed accordingly. Realignment of the DRUJ is assessed with fluo- roscopy, and passive forearm rotation is controlled at this point. If reduction of the DRUJ is not obtained despite distraction, a shortening osteotomy of the ulna may be performed simultaneously or delayed to a later date. If severe incongruity of the joint is present with secondary
degenerative changes, prosthetic replacement is advocated.
We no longer perform distal ulna resections because loss of the ulnar head invariably leads to radioulnar convergence and painful instability of the ulnar stump.21
While the distractor maintains alignment, the premolded plate is applied in a bridging fashion. Although most fore- arm nonunions are stabilized with 3.5 limited-contact dynamic compression (LCDC) plates with a minimum of 6 to 8 cortices for screw fixation on each fragment, the 4.5 nar- row DC plate may be recommended as a stronger implant to bridge large defects. Locking plates with angular stability may be also used, especially in osteoporotic bone. Augmen- tation of screw holding power with bone cement is still a valid alternative to increase stability of plate fixation in such situations.
The defect is then grafted with morcellized autologous bone grafts, taking care not to place them close to the IOM. If a soft tissue defect is present in this area, Gelfoam (Pfizer, New York, NY) is applied as a barrier to obliterate the dead space to reduce the danger of radioulnar synos- tosis. For smaller defects up to 3 cm, a corticocancellous strut graft may be interposed and fixed with screws to the plate (Fig. 18–2). The cortical border of the graft is placed
Figure 18–2 (A,B) Oligotrophic nonunion of the radial shaft following insufficient internal fixation of an Galeazzi fracture and early removal of the plate. Notice severe palmar angulation, shortening, and complete disruption of the distal radioulnar joint. (C,D)Following débridement of the necrotic bone ends, the nonunion was realigned and stabilized with
a 3.5 dynamic compression plate; the 3-cm defect was filled with a cor- ticocancellous structural iliac graft fixed to the plate with one screw.
(E,F)Radiographs 6 years after the operation. Notice full remodeling of the graft and restoration of the interosseous space. The patient regained full pronation and supination of her left forearm.
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opposite to the plate surface while the cancellous surface lies on the plate.22Morcellized cancellous grafts are addi- tionally placed in the proximal and distal junctions of the construct.
Restoration of length in smaller defects is achieved by fixing the plate with screws to the distal fragment and ap- plying the articulating tension device in distraction mode on the proximal end of the plate. This device permits a maximal excursion of 40 mm. Alternatively, for shorter distances and absence of soft tissue contractures a lami- nar spreader applied between the plate and a separate cortical screw can be used.23,24
A less common scenario is the nonunited ulna with a large defect and an intact radius. According to the short- ening and angulation, a concomitant dislocation of the radial head may be present. Similar tactical steps as described for the radius are recommended. In long- standing cases, an open reduction of the radial head and annular ligament reconstruction may become necessary.
If degenerative cartilage changes are present, prosthetic replacement of the radial head is preferred to resection, to obviate late proximal radius migration and secondary disruption of the DRUJ.
Infected Nonunions
If the nonunion presents with a draining sinus and ac- tive infection, an aggressive débridement; removal of implants, external fixation, temporary irrigation-suction;
and a prolonged course of parenteral antibiotics are per- formed as the first stage of the treatment. Sequential débridements and repeat cultures may become neces- sary in cases where the inflammatory signs persist.
Definitive reconstruction as described for the atrophic nonunion with large defects is indicated as soon as both the clinical and laboratory parameters of active infec- tion have normalized. It must be kept in mind, that revascularization of free morcellized cancellous graft is directly dependent on the vascularity of the soft tissue envelope. If the soft tissues surrounding a chronic infected nonunion reveal massive scarring, are devital- ized, or are associated with loss of muscle substance microvascular free tissue transfer is advisable (Fig. 18–3).
The most commonly used graft is an osteocutaneous fibular graft pedicled on the peroneal vessels.25,26The composite graft is placed into the defect having the per- oneal vessels in an appropriate position for an optimal anastomosis to the radial or ulnar recipient vessels according to the particular scenario. To minimize insta- bility and prevent delayed union, the graft junctions are stabilized to the recipient bone ends with plate or screw fixation or a combination of both. The cutaneous por- tion of the graft is sutured into the overlying soft tissue defect.