Operative Techniques in Orthopaedic Surgery (4 Volume Set) 1st Edition

249. Operative Treatment of Radius and Ulna Diaphyseal Nonunions

Rena L. Stewart

DEFINITION

images A diaphyseal forearm fracture is generally considered to be a nonunion if healing has not taken place within 6 months.

images Nonunions are generally classified as hypertrophic or atrophic, an important distinction in treatment selection.

images Hypertrophic nonunions have abundant callus and a rich blood supply and result from inadequate stability of fracture fixation. This type of nonunion is rare in the forearm and constitutes less than 10% of nonunion cases.9

images Atrophic nonunions are characterized by poor blood supply and little or no callus formation.

images Nonunion of the forearm diaphysis is rare because of the success of current techniques of plate and screw fixation. Nonunion rates of only 2% in the radius and 4% in the ulna are reported.2

ANATOMY

images The forearm consists of the radius and ulna, joined at either end by the proximal and distal radioulnar joints (PRUJ and DRUJ, respectively) (FIG 1).

images The ulna is straight, while the radius has both an apex radial and apex dorsal curvature.

images It can help to think of the forearm as a joint rather than a pair of long bones.

images Pronation and supination are achieved by rotation of the curved radius about the straight ulna.

images Both the curvature of the radius and the integrity of the interosseous space and interosseous membrane (IOM) must be maintained for the forearm “joint” to function optimally.

images The diaphyseal portions of the radius and ulna are surrounded by complex anatomy, including neural and vascular structures, that must be considered during any surgical approach. Both radius and ulna are covered by muscle proximally, while the ulna emerges distally to be subcutaneous.

images

FIG 1  The two bones of the forearm form a functional unit, with the axis of rotation extending from the radiocapitellar joint to the distal radioulnar joint.

PATHOGENESIS

images Nonunions of the diaphysis of the forearm are rare and result most commonly from incorrect or inadequate treatment.

images Inadequate fixation, generally less than six cortices of screw fixation proximal and distal to the fracture, will increase the rate of nonunion.

images Lack of attention to critical surgical principles such as creating compression across the fracture site (either with the use of an interfragmentary screw or a compression plate) also leads to nonunion.

images Nonoperative treatment results in markedly increased rates of nonunion and other complications.2 With the exception of isolated, minimally displaced ulnar shaft fractures, all adult diaphyseal forearm fractures require operative management.

images Comminution increases the risk of nonunion, with 12% of comminuted, diaphyseal fractures going on to develop nonunion after treatment with dynamic compression plates.11

images Fracture characteristics that increase the risk of nonunion include extensive devascularization and periosteal stripping, bone loss, and infection.

images Open, comminuted fractures with bone loss have the highest rate of nonunion.7

images Patient comorbidities known to increase rates of nonunion include diabetes mellitus, steroid use, malnutrition, and renal dysfunction.

NATURAL HISTORY

images Once a nonunion of the forearm is established, it will not go on to heal spontaneously.

images If significant shortening of either the radius or ulna occurs, the intricate anatomy of the entire forearm “joint” can be disrupted. Malalignment of the DRUJ secondary to such shortening can cause pain and lead to loss of motion at the wrist.

images Loss of motion secondary to pain, particularly pronation and supination, can lead to shortening and fibrosis of the IOM. This can lead to permanent loss of rotational motion in the forearm.

PATIENT HISTORY AND PHYSICAL FINDINGS

images Patients with nonunion of the diaphysis of the radius or ulna most commonly present with pain.

images This pain frequently worsens with attempts to use the extremity for lifting or pushing, but may also occur at rest.

images Resisted rotational movements are frequently painful, such as turning a key in a lock.

images It is important to explore whether infection could be the cause of the nonunion. Important history includes whether or not the original fracture was open, whether postoperative complications or drainage developed, and whether the patient has received antibiotics.

images During the physical examination, the examiner should do the following:

images Palpate the nonunion site for pain.

images Grasp the bone on either side of the nonunion and attempt to flex and extend the nonunion to assess fracture stability and healing. Palpable motion and increased pain indicate lack of union.

images Loss of flexion–extension in the elbow may result from pain. Loss of pronation and supination indicates deranged forearm anatomy or pain.

images Loss of flexion or extension at the wrist may indicate pain or scarring of muscle and tendons or IOM around the nonunion. Loss of radioulnar deviation may indicate DRUJ abnormality secondary to shortening at the nonunion site.

IMAGING AND OTHER DIAGNOSTIC STUDIES

images Plain radiographs are essential for diagnosis. This should include AP and lateral views of the forearm, elbow, and wrist.

images Comparative views of the contralateral forearm, elbow, and wrist are also essential for preoperative planning.

images Plain radiographs will allow the surgeon to determine if the nonunion is hypertrophic (FIG 2A) or atrophic (FIG 2B).

images CT is helpful in identifying synostosis, assessing rotational deformity, and evaluating the size of the gap between bone ends at the nonunion site. CT also allows assessment of the DRUJ and PRUJ.

images The metal suppression CT technique minimizes the bright scatter created by retained hardware.

images MRI is rarely used but can allow further evaluation of the IOM.

images A technetium-99m bone scan followed by an indium111–labeled leukocyte scan may be indicated when suspicion of an infected nonunion exists.

images False-positive and false-negative results occur.

DIFFERENTIAL DIAGNOSIS

images Malunion

images Infection

images IOM injury

images Painful hardware

NONOPERATIVE MANAGEMENT

images The goal of treatment is to alleviate pain and restore function to the forearm. This can rarely be accomplished without surgical intervention.

images In rare circumstances (if the patient is a high risk for surgery due to comorbidities, for example), an external bone stimulator can be used.

images A minority of patients develop a stable, fibrous nonunion that is painless and allows good function. Nonoperative management can be considered in such patients.

SURGICAL MANAGEMENT

images In all nonunions of the forearm, the first considerations are the patient's level of pain and function.

images The surgeon should not elect to operate based on radiographic findings alone.

images All patients with nonunions should undergo a workup to determine if the cause of the nonunion is infection, particularly after open fractures.

images The workup should include careful history of open fracture, drainage, or postoperative complications after initial surgery.

images Blood should be obtained for a complete blood count, erythrocyte sedimentation rate, and C-reactive protein.

images Nuclear medicine imaging should be performed if the suspicion of infection is high.

Preoperative Planning

images All imaging studies should be reviewed and pathoanatomy recognized.

images Plain radiographs should be reviewed for presence or absence of callus in order to categorize the nonunion as hypertrophic or atrophic.

images If a nonunion of the forearm is hypertrophic (which is rare), it may be treated by simple revision of hardware, creating compression across the fracture site with either a compression screw or a compression plate. This is the same technique that should be used for initial management of radius or ulna fractures (see Chap. HA-4).

images If any possibility of infection at the nonunion site exists, plans must be made to search for infection when the nonunion site is opened, and to have an alternative treatment plan if infection is encountered.

images Preoperative antibiotics may be held until cultures are obtained from the nonunion site (ensure the tourniquet is not inflated if antibiotics are administered later in the case).

images

FIG 2  A. Radiograph showing an infected, hypertrophic nonunion. The abundant callus formation indicates a biologically active nonunion. B. Radiograph showing an atrophic nonunion. There is complete absence of callus at the fracture site. The problem in an atrophic nonunion is lack of biologic activity. (Courtesy of Thomas R. Hunt III, MD.)

images Intraoperative culture swabs and tissue for aerobic, anaerobic, and fungal cultures should be obtained from sites within the nonunion.

images Patients should be made aware that if severe infection is encountered, the planned procedure may need to be altered. For example, if frank purulence is encountered, the nonunion repair may be abandoned in favor of débridement and irrigation with possible antibiotic bead placement and even external fixation if stability is compromised.

images Template the radiographs to ensure selection of proper plate size and length.

images DCP, LCDCP, and combination locking plates are all appropriate.

images A minimum of six cortices of screw purchase proximal and distal to the nonunion is critical. This may require plates longer than those available in a standard plating set.

images In osteoporotic bone, the use of locking plates should be considered.

images If bone graft will be required, the type of graft should be determined preoperatively. While autograft is still considered the gold standard, a vast array of bone graft substitutes are now available. The surgeon's preference and familiarity with various bone graft substitutes may guide this choice. It is important to determine if a structural graft will be required, as this may necessitate the use of autograft.

images Patients should be counseled regarding the possible need for (and risks associated with) various types of autograft, including the possible need for a tricortical iliac crest or fibula graft if significant bone loss is encountered.

images A vascularized fibula graft may be used to fill large defects, especially those associated with infection.1,4,6,12

images A complete examination of range of motion of the elbow and wrist, including pronation and supination, should be performed under anesthesia.

Positioning

images The patient should be positioned supine with the operative arm extended on a radiolucent arm table.

images A nonsterile or sterile tourniquet may be applied, but full access to the elbow is necessary.

images Because restoration of the radial bow is a critical component in restoring forearm motion, intraoperative radiographs showing the entire radius are essential. For this reason, use of the mini C-arm should be avoided in favor of regular fluoroscopy, with its much larger field of view.

images The selected site for harvest of autograft should also be prepared and draped.

Approach

images The approach to either the radius or ulna should generally be through the original surgical incisions.

images Approach to the radius is most commonly volar through the standard Henry approach. Proximal nonunions of the radius may be more easily accessed via a dorsal Thompson approach, particularly in muscular individuals.

images Care should be taken to identify and protect the posterior interosseous nerve during this approach.

images The ulna is accessed along the subcutaneous border in the interval between the flexor carpi ulnaris and the extensor carpi ulnaris.

images Care should be taken to identify and protect the dorsal cutaneous branch of the ulnar nerve distally.

images In all cases, preservation of blood supply is key to healing of a nonunion. Therefore, periosteal stripping should be kept to a minimum and the use of cautery should be restricted to vessel coagulation.

TECHNIQUES

PLATE FIXATION FOR TREATMENT OF FOREARM NONUNIONS

Preparation of the Nonunion

images  Determine the correct length of the radius or ulna by measuring the corresponding contralateral bone.

images  Expose the nonunion site and search for evidence of infection. If found, send specimens for Gram stain and culture and abort the planned procedure. Perform a two-stage reconstruction.

images Thoroughly débride all necrotic and infected bone and soft tissue. Remove all hardware.

images Place antibiotic-loaded PMMA beads in the gap.

images Begin a multiweek course of antibiotics before proceeding with definitive nonunion repair.

images  If infection is considered unlikely, after removal of all hardware, thoroughly débride the nonunion site of all necrotic and inflammatory tissue, synovial membranes, and sclerotic or avascular bone (TECH FIG 1A).

images Tools such as curved curettes, small rongeurs, and a small high-speed burr (with copious irrigation to prevent thermal injury to the bone) are helpful.

images Flatten the bone ends to allow for excellent fragment-to-fragment contact with compression.

images  Open the sclerotic bone ends using sequentially larger diameter drills.

images Pass these drills proximally and distally as far as possible to open the medullary canals (TECH FIG 1B).

images  Restrict elevation of muscle and periosteum to only what is needed to thoroughly débride the nonunion and to realign the bone.

images  Realign the bone and restore length by manipulating fragments with bone-holding forceps.

images Use of a small skeletal distractor, small external fixator, or lamina spreader aids in restoration of length.10

images  Measure the length of the residual bone defect directly and, taking into consideration the preoperative plan, determine the appropriate bone graft to use.

Compression Plating Without Bone Graft

images  In rare cases with minimal or no bone loss at the nonunion site, the bone may be plated in situ without causing shortening. Because the bone remains at normal length, the relationship of the radius and ulna at both the DRUJ and the PRUJ is not disrupted and rotation will be preserved.

images

TECH FIG 1  A. Complete débridement of the nonunion site is the essential first step. Any fibrous or necrotic material must be removed and the bone ends delivered. B. Medullary canals are opened using increasing-diameter drill bits to allow vascular ingrowth.

images This technique may also be used if there is nonunion of both the radius and the ulna. Both bones may then be shortened a symmetrical distance.

images  After bone preparation as detailed above, anatomically align the bone ends and precisely apply a compression plate using the same technique employed for acute forearm fractures.

images Ensure that compression of the bone ends is achieved.

images  If a small bone gap exists after compression, the other forearm bone may then be shortened to restore the length relationship.

images Because this approach involves surgery on a normal bone, this strategy should be used with caution.

Cancellous Bone Grafting

images  Cancellous bone grafting is generally used for small defects up to 3 cm that can be effectively stabilized with a plate.

images Gaps of up to 6 cm have been successfully treated using cancellous bone for grafting.9

images  Firmly pack the cancellous autograft into the residual nonunion defect after the plate is applied.

images  Ensure the graft does not escape from the nonunion site and come to lie on the IOM (TECH FIG 2).

Structural Corticocancellous Autograft Bone Grafting

images  Structural autograft harvested from the anterior or posterior iliac crest is used for larger defects.

images  Expose the superior crest and define the inner and outer tables.

images  Utilize a water-cooled sagittal saw and osteotomes to harvest a tricortical block of bone from the iliac crest. Additionally, harvest cancellous bone to fill defects that may present.

images The graft should be slightly larger than that required based on preoperative planning.

images  Precisely contour the graft to fit snugly into the defect. Square the ends of the graft to match the ends of the bone fragments.5

images Alternatively, cut both the bone ends of the radius or ulna and of the bone block chamfered, or on the bias, to increase the area of bony contact.3 This also allows the graft to be wedged securely in place.

images  Insert the graft before plate fixation and fill any residual gaps with cancellous bone after plate application.

images

TECH FIG 2  The nonunion gap is distracted if necessary to recreate the normal anatomic bone length. A 3.5-mm plate with a minimum of three screws proximal and distal should be used. Cancellous bone graft is inserted and packed in the nonunion gap.

Nonvascularized Structural Fibula Autograft With Cortical Allograft Bone Grafting

images  An appropriate-length segmental graft is harvested from the fibula and placed into the defect.

images  The fibula is approached laterally, via the intramuscular plane between the peroneal muscles and the soleus.

images  A cuff of muscle 2 to 3 mm in thickness should be left to protect the periosteum.

images  The IOM is incised longitudinally, taking care to avoid the posterior neurovascular bundle.

images  The fibula is osteotomized proximally and distally to create an appropriate-length graft.

images Complications of fibular harvest are rare but include transient motor weakness, peroneal nerve palsy, and flexor hallucis longus (FHL) contracture.

images A minimum of 6 cm of the distal fibula must be retained to avoid adversely affecting the distal tibiofibular syndesmosis and ankle joint function.

images  Insert the fibula graft into the defect and then apply the plate as described below, first placing the two screws just proximal and just distal to the nonunion to gain initial compression.

images  Select a cortical allograft several centimeters longer than the defect.

images Tibial allograft is recommended due to its suitable thickness and mechanical characteristics, which provide excellent screw purchase.8

images  Place the cortical allograft along the outer cortex of the bone, opposite the plate, spanning beyond the length of the fibula allograft.

images  Insert the remainder of the screws so that they pass through the plate and then the patient's bone and finally into the cortical allograft on the opposite side (TECH FIG 3).

images

TECH FIG 3  Combined intercalary autograft and allograft strut technique described by Moroni et al.8 After débridement of the nonunion site, an intercalary graft of appropriate length is harvested from the patient's fibula and placed in the gap. A cortical allograft is placed opposite to the plate, and screws are placed passing though the plate, the patient's radius or ulna, and finally the allograft strut.

COMPRESSION PLATE FIXATION

images  Select a 3.5-mm (small fragment) compression plate of adequate length to ensure a minimum of three or four screws (six to eight cortices) on either side of the nonunion.

images Always err on the side of a longer plate.

images Thinner locking plates may be considered when structural fibular autografts are combined with cortical allograft struts.

images  Fix the plate to the bone in compression (ensuring that proper length is maintained) with one screw proximal and one screw distal to the nonunion, then use full-length fluoroscopic views or radiographs of the forearm to ensure restoration of length, bow, and joint alignment.

images Compare with the contralateral forearm.

images  Insert the remaining screws.

images Ideally, screws are not placed into the graft itself and the graft is stabilized by the compression created by the plate (TECH FIG 4).

images  Close the wound routinely and apply an above-elbow or sugartong splint.

images

TECH FIG 4  Modified Nicoll technique with tricortical iliac crest graft. The graft is chamfered, allowing the graft to be compressed as the plate is applied.

images

POSTOPERATIVE CARE

images The longer motion is delayed after surgery, the greater the chance the patient will develop stiffness. Therefore, early active range of motion (ROM) should be initiated at the first postoperative visit, except in cases with more tenuous fixation.

images Use of the arm for activities of daily living is encouraged.

images If the patient has difficulty in achieving satisfactory ROM with active, active-assisted, and gentle passive ROM, static progressive splints may be used.

images Having the patient sleep in a static extension splint may significantly improve elbow extension.

images Heavy lifting, pushing, and weight bearing are delayed until radiographic evidence of healing is present, often 3 to 6 months after the index procedure.

OUTCOMES

images When precise surgical techniques are used, such as creating stable compression across structural grafts, high rates of union are expected.

images Rates of healing from 95% to 100% are reported for all of the methods described in this chapter.3,8,9

images Failure of union is related to recurrence of previous infection in nearly all cases. The prognosis for infected nonunions should be guarded.

images Patient satisfaction does not correlate directly with bony healing. In multiple studies only two thirds of patients achieved good or excellent results.3,5,8,9

images Unsatisfactory results are associated with poor postoperative motion in the majority of cases.

images Other injuries to the upper extremity (common in highenergy trauma associated with nonunions) contributed to unsatisfactory overall function in a minority of patients.9,10

images Because nonunion of the forearm diaphysis is a rare condition, no comparative studies of treatment methods exist, including the use of bone graft substitutes.

COMPLICATIONS

images Infection

images Graft displacement

images Recurrent nonunion and hardware failure

images Loss of motion

images Synostosis

images Pain or other complications at the autograft harvest site

REFERENCES

1.     Adani R, Delcroix L, Innocenti M, et al. Reconstruction of large posttraumatic skeletal defects of the forearm by vascularized free fibular graft. Microsurgery 2004;24:423–429.

2.     Chapman MW, Gordon JE, Zissimos AG. Compression-plate fixation of acute fractures of the diaphyses of the radius and ulna. J Bone Joint Surg Am 1989;71A:159–169.

3.     Davey PA, Simonis RB. Modification of the Nicoll bone-grafting technique for nonunion of the radius and/or ulna. J Bone Joint Surg Br 2002;84B:30–33.

4.     Dell PC, Sheppard JE. Vascularized bone grafts in the treatment of infected forearm nonunion. J Hand Surg Am 1984;9A:653–658.

5.     Grace TG, Eversman WW. The management of segmental bone loss associated with forearm fractures. J Bone Joint Surg Am 1980;62A: 1150–1155.

6.     Jupiter JB, Gerhard HJ, Guerrero J, et al. Treatment of segmental defects of the radius with use of the vascularized osteoseptocutaneous fibular autogenous graft. J Bone Joint Surg Am 1997;79A: 542–550.

7.     Moed BR, Kellam JF, Foster JR, et al. Immediate internal fixation of open fractures of the diaphysis of the forearm. J Bone Joint Surg Am 1986;68A:1008–1017.

8.     Moroni AG, Rollo G, Guzzardella M, et al. Surgical treatment of isolated forearm non-union with segmental bone loss. Injury 1997;28: 497–504.

9.     Ring D, Allende C, Jafarnia K, et al. Ununited diaphyseal forearm fractures with segmental defects: plate fixation and autogenous cancellous bone-grafting. J Bone Joint Surg Am 2004;86A: 2440–2445.

10. Ring D, Jupiter JB, Gulotta L. Atrophic nonunions of the proximal ulna. Clin Orthop Relat Res 2003;409:268–274.

11. Ring D, Rhim R, Carpenter C, et al. Comminuted diaphyseal fractures of the radius and ulna: does bone grafting affect nonunion rate? J Trauma 2005;59:436–440.

12. Safoury Y. Free vascularized fibula for the treatment of traumatic bone defects and nonunions of the forearm bones. J Hand Surg Br 2005;30B:67–72.



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