Look for this and other related articles in Instructional Course Lectures, Volume 59, which will be published by the American Academy of Orthopaedic Surgeons in March 2010:"The Management of Complex Fractures and Fracture-Dislocations of the Hand," by Jesse Jupiter, MD, Hill Hastings, MD, and John T. Capo,MDForearm rotation is the most important contribution to the rotational mobility of the upper limb1. The two-bone unit with its proximal and distal radioulnar joints, and its rotational axis connecting the centers of the two, have been viewed as a single bicondylar joint. When combined with rotational motion of the shoulder, forearm rotation permits the hand to be positioned through an entire 360° arc of motion. With the shoulder fully abducted, nearly all of the rotational motion of the upper limb occurs through the forearm1. Activities such as accepting objects in the palm of the hand require nearly full forearm supination, while many other functional tasks require some degree of pronation. It has been suggested that, in addition to rotation along the axis of the forearm articulation, the distal aspect of the ulna moves in both adduction and abduction planes with forearm rotation, although some believe that this perceived motion may be due to axial rotation of the humerus2,3.
Look for this and other related articles in Instructional Course Lectures, Volume 59, which will be published by the American Academy of Orthopaedic Surgeons in March 2010:"The Management of Complex Fractures and Fracture-Dislocations of the Hand," by Jesse Jupiter, MD, Hill Hastings, MD, and John T. Capo,MD
"The Management of Complex Fractures and Fracture-Dislocations of the Hand," by Jesse Jupiter, MD, Hill Hastings, MD, and John T. Capo,MD
The interosseous membrane, which is considered to be better described as a ligament, also contributes to the longitudinal stability of the forearm4-7. The central band contributes to the axial stability of the forearm, while the dorsal oblique band adds to the stability of the proximal radioulnar joint and the distal membranous portion functions as a secondary stabilizer of the distal radioulnar joint7.
When the forearm is considered to be a joint, diaphyseal fractures constitute intra-articular lesions and therefore require accurate anatomic reduction to ensure full function. The same principle applies to surgical reconstruction of malunited forearm fractures.
Surgical management of a diaphyseal malunion is a challenge because, despite the achievement of osseous union, correction of deformity, and relief of pain, complete and symmetrical restoration of forearm rotation is difficult to obtain8. This is due to the associated derangement of the proximal and distal radioulnar joints and the interosseous membrane9,10. Shortening of a single forearm bone with or without angular deformity automatically affects the articular anatomic relationships of either the proximal or the distal radioulnar joint. Loss of the physiological bow of the radius limits pronation, and reduction of the interosseous space associated with angular or translational deformity can lead to osseous impingement and secondary contracture of the interosseous membrane, further reducing forearm rotation10 (Fig. 1-A).
Diaphyseal malunion in adults may be due to insufficient reduction, usually with nonoperative treatment, or may be an iatrogenic deformity after an attempted osteotomy. The deformity may include one or both bones of the forearm. The clinical scenario presents as restriction of forearm rotation, pain and instability of the radioulnar joints during pronation and supination, and often a cosmetic problem. Symptoms may be decreased by correcting all components of the deformity, including length discrepancy, angulation, rotation, and the bow of the radius9.
In children over ten years of age and adults, restoration of normal anatomy and neighboring joint relationships following posttraumatic deformity can be achieved only with corrective osteotomies. This together with the appropriate soft-tissue release improves forearm rotation, while realignment of the radioulnar joints provides stability. Because there are no generally valid normal values, the contralateral, healthy forearm is used for preoperative planning. Fluoroscopy, computed tomography scans, and cross-sectional magnetic resonance imaging are used to assess rotational malalignment while three-dimensional plastic models based on the computed tomography scans are used to assess complex deformities11-13.
Pathomechanics of Forearm Malunions and Clinical Correlation with Forearm Rotation
The influence of ulnar and radial malalignment on rotational motion has been demonstrated experimentally on cadaver forearms14-17. The amount of angulation directly correlates with the restriction of pronation and supination. Deformities in the distal third of the forearm, but not those in the middle or proximal third, decrease pronation14. Angulations of up to 10° in the middle third of the radius or ulna, or both, do not limit rotation, but deformities of 20° restrict forearm rotation by at least 30% and angulations of >20° result in even greater restrictions14,15. Rotational deformities may also displace and decrease the pronation-supination arc of motion18,19.
Diaphyseal Deformity and Instability of the Distal Radioulnar Joint
Instability of the distal radioulnar joint can occur with angulation, malrotation, and length discrepancy of one or both forearm bones19. The loss of the normal spatial orientation of the joint surfaces prevents anatomic healing of acutely torn ligament restraints. This is true for fractures localized to the distal third of the radius20,21. If the fracture heals with a skeletal deformity, instability, subluxation, or complete dislocation with incompetence of the triangular fibrocartilage complex may occur21. Palmar subluxation of the distal part of the ulna is associated with dorsally angulated diaphyseal malunion. Conversely, malreduced Galeazzi fractures with persistent palmar angulation and pronated rotational malalignment are associated with dorsal displacement of the distal part of the ulna and complete loss of active supination.
Associated Disorders of the Proximal Radioulnar Joint
Chronic dislocation of the radial head can result from an unreduced Monteggia fracture with persistent angulation of the ulna or be associated with a forearm malunion with a discrepancy between the lengths of the radius and the ulna. An angulated metaphyseal malunion of the proximal part of the radius leads to incongruity of the radial head in the sigmoid notch and results in severe limitation of pronation. In general, valgus malalignment of the proximal part of the radius results in lateral subluxation of the radial head, creating substantial incongruity of both the proximal radioulnar joint and the radiocapitellar joint.
Surgical Techniques
Types of Osteotomies
A transverse osteotomy is preferred to treat a "simple" rotational or translational deformity. Moderate lengthening with angular correction in the plane of the osteotomy can be achieved with oblique osteotomies22,23. Rotational correction with oblique osteotomies is limited because rotation automatically induces a change in angular alignment and opens the osteotomy on one side, reducing the contact surface. For complex diaphyseal malunions, for which angular, rotational, and length adjustments are to be made, the single-cut osteotomy oriented in the combined oblique plane of deformity based on a mathematical analysis of the malalignment has been proposed24. Further refinements for planning and performing the single-cut osteotomy by applying a geometrical methodology were reported by Meyer et al.25. For an exact calculation of the true angle of deformity, Nagy recommended the use of tables that readily provide these values on the basis of projected angles of the deformity on anteroposterior and lateral radiographs26. During the performance of a single-cut osteotomy, the decision to create a closing or opening wedge osteotomy depends on the amount of length discrepancy of the involved bone. In patients with extreme bowing of the radius or a malunited segmental fracture, a double-level osteotomy may be required to restore alignment of the anatomic axis. Classically, step-cut osteotomies, although technically more demanding, have been used to lengthen long bones, thereby avoiding the need for bone-grafting. An isolated rotational deformity is corrected with a transverse osteotomy27. Osseous defects created by lengthening require bone-grafting except in children, in whom rapid periosteal bone-healing readily fills the bone gap.
Deformity characterized by >4 cm of shortening of one forearm bone, such as occurs following physeal trauma, is better addressed with progressive distraction/osteogenesis techniques that employ external fixation.
Preoperative Planning
The contralateral, normal forearm is used as a guide for preoperative planning as the correctional osteotomy should reproduce the osseous geometry of the normal side. Exact anteroposterior and lateral radiographs of both the radius and the ulna, including the proximal and distal joints, should be obtained. This may be difficult, especially when limited forearm rotation prevents the patient from placing the forearm in neutral rotation. In these cases, the correct position for exposure must be determined under an image intensifier. The distal epiphysis is used as the reference for the radius, and the humeroulnar joint is used for the ulna.
The contours of the healthy and deformed bones in both projections are drawn on separate sheets of tracing paper (Figs. 1-B and 1-C). The location of maximal deformity is determined by simple superimposition of the drawings. The angular deformity in both planes is measured with use of the values of these projected angles; the true angle of deformity and the orientation of the deformity in space are calculated with use of established tables19. In contrast, rotational deformity is determined by inspecting the relationship of the bicipital tuberosity to the radial styloid and the relationship of the coronoid process to the ulnar styloid. The exact degree of radial and ulnar torsion is measured by comparing the computed tomography or magnetic resonance images of the two forearms. The bicipital tuberosity and the square section of the radius at the level of the Lister tubercle are used to determine radial torsion, whereas the trochlea and the ulnar styloid are most commonly used for the ulna12,28. Rotational malalignment of the radius of >30° and rotational malalignment of the ulna of >20° should be corrected, since these values exceed the physiological limits of individual variations6.
To decide whether an opening or a closing-wedge osteotomy is suitable, the ulnar variances of the malunited and healthy sides are compared. If a single-cut closing-wedge osteotomy is performed, the wedge should include the true angle of correction. The base of the wedge is measured in millimeters and is included in the preoperative drawing. In an opening-wedge osteotomy, a variable amount of lengthening can be achieved with use of an interpositional bone graft, preferably a compression-resistant corticocancellous graft from the iliac crest. This graft, which may be triangular or trapezoidal in shape, should also include the true angle of deformity.
Techniques for Diaphyseal Osteotomies
We prefer the Henry approach for exposure of the entire radius29. Proximal extension of this approach allows the surgeon to perform an anterior elbow joint arthrotomy to treat associated pathological conditions of the proximal radioulnar joint. Subperiosteal detachment of the supinator muscle and protection of the motor branch of the radial nerve are necessary for proximal osteotomies, whereas temporary release of the pronator teres may be needed for a midshaft malunion. The interval between the flexor and extensor carpi ulnaris is used to expose the ulna.
When both the radius and the ulna are malunited, the ulna should be realigned first. The radial realignment can then be "fine-tuned" to correct length and angular discrepancies to obtain accurate congruency of the radioulnar joints.
The site of the osteotomy (the apex of maximal deformity) is determined in the operating room on the basis of the distance from the distal or proximal end of the bone as measured on preoperative radiographic images. Before the osteotomy is performed, two Kirschner wires are placed to mark the exact anteroposterior and lateral planes proximal and distal to the osteotomy. A plate (usually a six or eight-hole 3.5-mm compression plate) is temporarily fixed to the proximal fragment and is contoured to achieve the desired correction. In the middle third of the radius, shaping the plate to reconstruct the physiological radial bow is of paramount importance.
The plate is then removed, and the base of the wedge is marked. If the angular deformity has markedly reduced the interosseous space, the scarred interosseous membrane should be released and partially resected prior to the osteotomy to facilitate reduction of the osteotomy. If a closing-wedge osteotomy is planned, the converging cuts are oriented in the plane of the true deformity. The osteotomy is closed with an intact periosteal hinge, and the plate is reapplied and is fixed to the distal fragment with one screw. The quality of the reduction is checked with fluoroscopy, and the amount of passive rotation is determined. If there is no substantial increase compared with the preoperative range of motion, a release of the interosseous membrane is performed. If, despite these measures, a reasonable improvement in rotation is not obtained, the radius should be derotated to achieve a balanced arc of rotation with at least 50° of pronation and 50° of supination. If bone graft is needed, interpositional corticocancellous bone blocks are preferred. If additional morselized grafts are used, they should not be placed adjacent to the interosseous membrane, as doing so increases the risk of creating a radioulnar synostosis. Associated subluxation of the distal radioulnar joint with malunion of the radial shaft (a healed Galeazzi fracture) usually does not require open reduction of the joint. Restoration of radial length and angular deformity should result in adequate congruity and stability of the joint.
Early active and passive-assisted range-of-motion therapy is begun on the second postoperative day. If passive motion does not reach 60% of that on the contralateral side by four weeks postoperatively, dynamic splinting for pronation and/or supination is begun. Strengthening is started at six to eight weeks after the surgery, and full weight-bearing and sports are allowed once solid bone-healing has been confirmed.
Techniques for Posttraumatic Chronic Radial Head Dislocations
Chronic radial head dislocations are less common in adults than they are in children, but they may be seen in a patient with a neglected initial subluxation associated with a complex high-energy forearm injury or in one with bipolar fracture-dislocations30-33. The most important factor responsible for the chronic dislocation is insufficient reduction leading to posttraumatic ulnar shortening (Fig. 2-A), not the loss of ligamentous restraints such as the anular ligament and the proximal part of the interosseous membrane. The discrepancy between the lengths of the radius and ulna is readily assessed by comparing radiographs of the affected and contralateral forearms. Open reduction of the radial head with simultaneous radial shortening is performed through a proximally extended Henry approach. The elongated capsule of the lateral elbow compartment is exposed between the brachioradialis and brachialis muscles after isolating and protecting the radial nerve. The proximal part of the radial shaft is exposed through subperiosteal detachment of the supinator muscle while the posterior interosseous nerve is visualized. The radius is shortened by the difference between the lengths of the ulnae on the affected and healthy sides (Fig. 2-B). The plate is temporarily fixed with two screws into the proximal fragment. The predetermined transverse segment of bone is removed, and the plate is reapplied under compression. After the radius is shortened, the radial head usually reduces without tension against the capitellum. The elbow should be examined in full flexion, extension, and rotation to prove that the radial head is stable. Then, the capsule is closed, with resection of any excessive capsular tissue. Reconstruction of an anular ligament is not necessary if spontaneous reduction is maintained through a passive range of motion.
Discussion
Several outcome studies have shown that satisfactory functional improvement can be expected after surgical correction of forearm malunions sustained in childhood34-37. Trousdale and Linscheid reported that the results in adult patients treated within a year after the initial injury were substantially better than those in adults who were treated later38. In a recent report by Nagy et al., seventeen patients with a malunited forearm fracture were divided into three groups according to the clinical problem and the presentation of the deformity: (1) limitation of pronation, (2) limitation of supination, and (3) distal radioulnar joint instability19. Ten patients had osteotomies of both the radius and the ulna, and seven had an osteotomy of the radius alone. The interosseous membrane was released in nine patients. Bone-healing was uneventful in all cases, and no complications, infections, refractures, or synostoses occurred. Sixteen of the seventeen patients reported subjective improvement, whereas one patient needed a repeat osteotomy to treat a residual symptomatic deformity and then had improvement as well. Patients with limited supination had better functional improvement after the osteotomy than did those with limited pronation. Stability of the distal radioulnar joint was restored after skeletal realignment of the radius without adjuvant ligament reconstruction, and release of the interosseous membrane did not impair function, including strength and stability.
General Reconstructive Options
The management of diaphyseal skeletal defects of the forearm is a complex, often multistage process, and vascularized fibular transfer has proven to be an effective reconstructive procedure in this setting39-44. Defects of <6 cm can be successfully treated with cancellous autograft or allograft, although this approach is less predictable in the presence of infection or following radiation therapy44,45. Alternatively, external fixation with bone transport works well and can be used to treat gaps of up to 3 cm, but the external fixation usually must be in place for several months and is fraught with complications such as infection and stiffness46,47. An additional reconstructive option for segmental bone loss is the creation of a one-bone forearm, but this eliminates all forearm rotation and should be considered to be a final salvage option48,49.
Free bone transfer with microsurgical anastomoses is technically challenging and is associated with some donor site morbidity but has several distinct advantages50-52. Vascularized grafts heal rapidly, and periosteal new bone formation begins early irrespective of graft length. In contrast, nonvascularized grafts must undergo revascularization and creeping substitution before they are fully consolidated53,54. Because of its size and cortical nature, use of a free vascularized fibular graft is the treatment of choice for large segmental defects of the forearm50,55,56. Up to 26 cm of the fibula on a single vascular pedicle is available for reconstruction57.
In the presence of associated soft-tissue defects in the forearm, a skin paddle of up to 10 × 20 cm can be transferred with the fibula. This skin pedicle is based on the peroneal artery, and a 6 × 7-cm graft based on each septal perforator can be transferred with the fibula as an osteoseptocutaneous flap for single-stage reconstruction of combined skeletal and soft-tissue defects in the forearm44,50,55,58-61. The skin paddle also serves as a means of monitoring the vascular status of the graft60.
Osteoseptocutaneous Free Vascularized Fibular Flaps
The vascular pedicle of the vascularized fibular osteoseptocutaneous flap is the peroneal artery55,56. The artery has two venae comitantes and lies in the posterior compartment of the leg between the tibialis posterior and flexor hallucis longus muscles.
Clinical and cadaver evidence suggests that the best location for the skin paddle is at the junction of the middle and distal thirds of the fibula, 8 to 12 cm proximal to the ankle mortise, where the most consistent supramalleolar septocutaneous perforator is located62.
Preoperative angiography of the lower limb is not recommended routinely but is recommended for patients with atherosclerosis or symptoms of vascular insufficiency. Angiography of the recipient upper extremity, especially when there has been trauma or previous surgery, is indicated to establish the pedicle length that will be needed. An abnormal result of the Allen test should also prompt angiography. When planning the length of the fibular graft, one should err on the side of a longer graft. Achieving an appropriate final length is critical for alignment of the distal radioulnar joint, and it is much easier to trim excess bone than to make up for a residual deficit in length.
The procedure is preferably done with the patient under general anesthesia because of its anticipated duration, but use of a supplementary regional blockade of the donor or recipient limb can assist with postoperative pain control. The patient is placed in the lateral decubitus position, with the affected upper extremity down and lying on an arm-board and the contralateral donor leg up. The arm should be prepared to the axilla, and a sterile tourniquet is used. The donor leg should be prepared to the groin, with sufficient space left for a skin-graft harvest from the proximal part of the thigh, if necessary.
A two-team approach with simultaneous preparation of the recipient site and harvest at the donor site is recommended. The radial artery should be utilized when possible, as it is usually not the primary source of blood flow to the hand. Two recipient veins should be identified and prepared as well.
Although up to 26 cm of viable fibular bone can be harvested, it is preferable to leave 8 to 10 cm of the fibula distally to maintain ankle stability and 7 cm is left proximally for protection of the peroneal nerve. The specific surgical techniques of harvesting the osteocutaneous fibular transfer have been thoroughly described50,58-61.
Before the vascular anastomoses in the forearm are performed, the fibular graft should be placed in its expected final position and a posteroanterior radiograph of the wrist in neutral rotation should be made to verify anatomic restoration of the forearm axis, ulnar variance, and congruity of the distal radioulnar joint. Stable fixation is then achieved with small-fragment compression plates. This can be done by either direct fixation with a compression plate of the site of a transverse osteotomy or conversion to a step-cut osteotomy. Standard microvascular anastomoses of one artery and two veins are done.
Although patients are instructed to not bear weight on the donor extremity for six weeks, they are encouraged to start early motion of the toes and ankle, focusing especially on passive stretching of the great toe, which is prone to the development of a flexion contracture. The forearm and elbow are immobilized in a sugar tong splint or long arm cast until there is radiographic evidence of union.
Results
The reconstruction of defects due to trauma, infection, and tumor have been reported to have encouraging results, with times to union of approximately four months63-66. Adani et al. reported that eleven of twelve patients with a posttraumatic forearm defect, ranging from 6 to 13 cm in length, had successful union at a mean of 4.8 months39. Two patients required additional bone-grafting to achieve consolidation, and an osteoseptocutaneous flap was used in four patients. We previously used an osteoseptocutaneous fibular flap to treat nine patients with a large defect of the radius and an associated soft-tissue defect50 (Figs. 3-A, 3-B, and 3-C). The mean radial defect was 7.9 cm, and the soft-tissue defect averaged 11.8 × 5.9 cm. All cutaneous flaps survived, and all but one patient obtained osseous union at both host-graft junctions. There were no donor site complications. Kumar et al. treated seven patients (five with a tumor and two with an infection) with application of a free vascularized fibular flap to the forearm67. The mean time to union was 3.8 months. There were two nonunions, one of which was converted to a one-bone forearm and the other of which was not treated. Safoury treated eighteen patients with application of a free vascularized fibular graft to the forearm to bridge a posttraumatic segmental defect (mean, 17 cm) and reported a 100% rate of union at a mean of four months68.
Donor site morbidity is not frequent after treatment with a fibular flap, but gait analysis has shown decreased walking velocity in comparison with control values68,69. Ankle valgus is a potential problem in children, and screw stabilization of the distal tibiofibular syndesmosis has been recommended43,70. Ankle malalignment or instability has not been a problem in adults71. Decreased motion and strength of the great toe have also been observed. We believe that avoiding tight closure of the flexor hallucis and peroneal muscles and the skin interval helps to prevent this problem. Complications at the recipient site include nonunion, fracture of the graft, and thrombosis of the vascular pedicle41,50.
The assessment and management of adverse sequelae of traumatic injury to the forearm can be exceedingly complex. The loss of forearm rotation has a substantial impact on effective function of the entire upper limb. The problems can include diaphyseal deformity, bone or soft-tissue loss, or a failure to heal—either alone or often in combination. Careful preoperative planning is essential to accurately define the extent and location of the clinical problem, establish a precise surgical plan, and better inform the patient regarding the risks and goals of the procedure.