Humeral Shaft Fractures
Kenneth J. Koval, MD
At the 21st Annual Orthopaedic Trauma Seminar held Feb 28-March 3, 2000, in Snowmass, Colorado, Kenneth D. Johnson, MD presented the surgical indications for plate stabilization versus intramedullary nailing for humeral shaft fixation. Humeral shaft fractures are common injuries, accounting for approximately 3% of all fracture, most can be managed without surgery with anticipated good to excellent results. Appropriate nonoperative and operative treatment of humeral shaft fractures, however, require an understanding of humeral anatomy, the fracture pattern, and the patient's activity level and expectations.
The radiographic views of a suspected humeral shaft injury should include the shoulder and elbow joint. The standard films are anterior-posterior and lateral views of the extremity taken at 90 degrees to each other. The radiographs should be done by moving the patient's whole body as opposed to simply attempting to rotate the injured arm.
The AO/ASIF classification of humeral shaft fractures is based on fracture comminution: Type A are simple (noncomminuted) fractures, Type B have a butterfly fragment, and Type C are comminuted. These classifications are further broken down by fracture pattern.
Humeral shaft fractures generally unite in an acceptable position without surgery Most nondisplaced or minimally displaced humeral shaft fractures can be successfully managed with a coaptation splint followed by a functional fracture brace at 1 to 2 weeks. Patients with displaced, midshaft humeral fractures with shortening -- especially if the fracture has an oblique or spiral pattern -- are candidates for a hanging arm cast.
Open humerus fractures require emergent debridement; fracture stabilization after soft tissue and osseous debridement can reduce the incidence of infection. Fractures that have concomitant vascular injury require stabilization to safeguard vessel healing and repair. Ipsilateral fractures of the humerus and radius/ulna ("floating elbow") are best managed with osseous stabilization followed by early range-of-motion 3] Internal fixation of segmental humerus fractures is recommended; nonoperative treatment is associated with an increased rate of nonunion at 1 or both fracture sites. Bilateral humerus fractures require operative stabilization to facilitate patient self-care. Patients with polytrauma may be unable to sustain the semisitting posture recommended for effective fracture reduction; furthermore, operative stabilization supports the general rehabilitation of these patients.
Pathologic fractures should be internally stabilized to optimize patient comfort and extremity function. Neurologic loss after penetrating stab injury is an indication for nerve exploration. The need for operative intervention secondary to radial nerve dysfunction after fracture manipulation is controversial -- there are advocates for both early nerve exploration and observation. Fractures that cannot retain appropriate alignment are candidates for operative stabilization. Twenty degrees of anterior or posterior angulation, 30 degrees of varus, and 3 centimeters of shortening is acceptable. However, in thin individuals who have a humerus fracture, less angular deformity may be preferable. Obese patients and female patients with large, pendulous breasts are at greater risk for varus angulation after humerus fracture. Fracture malrotation secondary to compensatory shoulder motion is generally well tolerated. Finally, humeral shaft fractures that extend to or include the articular surface also necessitate open repair.
Operative Fixation by Using Plates and Screws
The best functional results after operative humeral shaft fracture management have been reported with use of plates and screws; these implants allow direct fracture reduction and stable fixation of the humeral shaft without violation of the rotator cuff. More definitive indications for use of plates and screws include humeri with small medullary canals or preexisting deformity, proximal and distal humeral shaft fractures that are not amenable to intramedullary nailing, humerus fractures with intra-articular extension, humerus fractures that require exploration for evaluation and treatment of an associated neurologic or vascular lesion, and humeral nonunions.
The operative approach for plating of the humerus is subject to the location and level of the fracture and the need to expose and visualize the radial nerve. The anterolateral approach is preferred for proximal third fractures; the anterolateral and posterior approaches are both adequate for midshaft and distal third fractures.
During fracture exposure, care should be taken not to devitalize butterfly fragments and to avoid excessive stripping of soft tissue. For midshaft humerus fractures, a 4.5-mm narrow dynamic compression plate is typically used. A precontoured plate can be used as a reduction aid, depending on the fracture level. Fracture pattern permitting, the plate should be applied in compression, through use of either the self-compressing holes in the dynamic compression plate or the articulating tensioning device. Lag screws are used in all possible instances. The screw should fixate 8 to 10 layers of cortex proximal and distal to the fracture. Fixation stability is evaluated before closure. The degree of fracture comminution and the amount of soft tissue dissection determine whether a bone graft is needed.
Although use of intramedullary nails for humeral shaft fixation has been a subject of much interest, a high incidence of shoulder pain has been reported after antegrade humeral nailing.[8,9] The best indication for use of an intramedullary nail may be a pathologic humerus fracture.
Most interlocked intramedullary nails depend on proximal and distal screw fixation to provide fracture stability. The screws are able to preserve the alignment of unstable fracture patterns and prevent shortening as well as malrotation. The level of fracture appropriate for interlocked nails is from 2 centimeters distal to the surgical neck to 3 centimeters proximal to the olecranon. The nails can be inserted antegrade through the rotator cuff or retrograde proximal to the olecranon.
To avoid nail impingement under the acromion with antegrade nail insertion, the humeral nail should be embedded below the rotator cuff. However, a high incidence of shoulder pain has been reported with antegrade insertion even if the nail is buried below the cuff. Subacromial impingement may also occur if oblique, proximal locking screws are inserted from proximal-lateral to distal-medial and are located proximal to the equator of the humeral head. During proximal locking screw insertion, the axillary nerve is also at risk for injury.
Close monitoring of the patient during the rehabilitation program is essential to achieve maximum function after both operative and nonoperative management of humeral shaft fractures. Early and vigorous postsurgical range-of-motion exercises of the hand and wrist should be strongly urged. As shoulder pain diminishes, range-of-motion exercises for the shoulder and elbow are initiated. As union progresses, supervised exercises to recover upper extremity strength are started. Postoperative management of the elbow should be done cautiously -- the elbow should not be passively stretched. Myositis ossificans, which has been reported around the elbow after humeral shaft fracture, can be prevented by exclusive use of active range-of-motion exercises.
According to the literature, 4 months is a suitable length of time for union of a humeral shaft fracture to be established.[10,11] If nonunion has occurred, the potential for union no longer exists. The rate of nonunion associated with humeral fractures ranges from 0% to 15%. The areas at greatest risk are the proximal and distal portions of the humerus. Transverse fracture pattern, fracture distraction, soft tissue interposition, inadequate immobilization, and restricted limitation of shoulder motion are all associated with an increased risk for nonunion. Other predisposing factors include older age, poor nutritional status, steroid use, anticoagulation, prior radiation therapy, and fracture immediately adjacent to a burn. Operative management is associated with higher rates of nonunion than nonoperative management.
Nonunion is best treated with compression plating. Surgical objectives include creation of osseous stability, elimination of the nonunion gap, maintenance or restoration of osseous vascularity, and elimination of infection. Two recent series have reported excellent results for treatment of humeral nonunion with compression plating combined with cancellous bone grafting. Barquet and coworkers reported successful union in 24 of 25 (96%) aseptic nonunions of the humerus. Rosen reported a 97% healing rate with 1 surgical procedure in 32 humeral nonunions treated with plates and screws.
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