December 2020

12/30/2020 | BY Cheryl R. Lawing, MD, Shriner’s Healthcare for Children - Florida 

5 Tips for Pinning a Supracondylar Humerus Fracture

1. Recognize the Deformity:  

Supracondylar humerus fractures can be more than just a sagittal plane issue. Varus deformity can be easy to miss at the time of injury in type II fractures, when one is easily focused on the lateral radiograph. Carefully analyze your AP radiograph, looking for medial column comminution that will result in ultimate varus deformity. (See figure 1) This can be subtle in Gartland type II fractures and is easy to overlook if focused solely on the extension deformity.  

Bauman’s angle can be used to help assess for coronal plane deformity.1 Bauman’s angle is measured by a line down the center of the humeral shaft and a line tangential to the capitellum (See Figure 2). Normal angles were reported by Baumann to be between 75 and 80 degrees.2 A subsequent study showed the average Baumann’s angle to be 72 degrees, with a standard deviation of 4 degrees and a 95% confidence interval in normal elbows between 64 and 81 degrees.3 Rotation of the elbow, however, can have an impact on measurements.4 If in doubt of coronal plane deformity, radiographs of the uninjured contralateral elbow can be obtained for comparison. 

 Figure 1: Medial comminution will result in varus deformity if not treated appropriately 
Figure 2: Bauman’s angle is measured by a line down the center of the humeral shaft and a line tangential to the capitellum. The image on the left shows the uninjured contralateral right elbow with a normal Bauman’s angle. The image on the left shows the injured left elbow with medial comminution that has resulted in varus deformity. 

2. Document a good neurovascular exam and know when to act emergently.  

Neurovascular exam can be difficult to elicit in an anxious and hurting child but is essential in the decision making process. From a vascular standpoint, palpation of the radial artery is important. Vascular injury has been reported in up to 38% and nerve injury in up to 49% of patients with displaced type III supracondylar humerus fractures.5 

If the radial pulse is absent, it is essential to carefully evaluate the perfusion of the hand. Hand temperature, color, swelling, and digital turgor are important indicators of perfusion. Capillary refill should be compared to the uninjured side. Antecubital ecchymosis and skin puckering raise concern for possible underlying neurovascular injury. Compartments should be palpated. In children, signs of compartment syndrome are typically increasing anxiety and agitation as well as need for pain medication.6 When neuropraxia and nerve injuries are present, sensory deficits can mask compartment syndrome and very close observation is necessary. The majority of patients with concomitant nerve injuries can still be treated with closed reduction. However, they should be observed inpatient post-operatively to monitor for compartment syndrome.7 

A pale pulseless hand needs emergent intervention. Gentle traction and splinting in 30-45 degrees of flexion can sometimes restore perfusion by decreasing the tension on the anterior neurovascular structures.8 If this restores perfusion, urgent operative intervention is still necessary. If the hand remains cold and pale, emergent operative intervention is necessary. Closed reduction and percutaneous pin fixation is performed. If perfusion is not returned, anterior exploration is necessary to investigate arterial injury entrapment in the fracture. This can be done through a 4-5 cm transverse anterior incision in the antecubital flexion crease.8 (Figure 3) 

In the case of a pink (perfused) pulseless hand, CRPP can be attempted on an urgent, rather than emergent, basis. If the pulse does not return after closed reduction but the hand remains well perfused, inpatient observation for 24-48 hours is necessary to monitor for compartment syndrome.9,10 

 

Figure 3: A curvilinear incision over the antecubital fossa creates good exposure for evaluation of neurovascular injury. The anterior structures of the elbow will be draped over the distal edge of the distal humeral metaphysis. 

 

 

3. Obtain good stability with good pin spread:  

Appropriate pin fixation with good pin spread is necessary to achieve stability. You should visually divide the fracture into thirds. Pins should be in separate thirds of the fracture. If too close together, the fracture will still be rotationally unstable. Once two lateral pins have been placed with appropriate spread, the elbow can be stressed under pulse fluoroscopy to assess coronal and sagittal stability. If additional fixation is needed, a third lateral pin has been shown to provide good stability.11,12 However, depending on the fracture obliquity, a medial pin may be necessary to provide better stability.  

Pin size is another factor to consider. While 1.6 mm diameter pins are most commonly used, the relative size of this pin varies greatly with patient size. Better maintenance of sagittal plane correction has been demonstrated with larger pins. Srikumaran developed the concept of pin size ratio with the diameter of the pin compared to the diameter of the cortex of the midshaft of the humerus. Ratios >0.9 indicate a large pin size and have better ability to prevent loss of sagittal correction, which can occur when undersized pins bend post-operatively.13 

 


4. Safe insertion of medial pins:  

Biomechanically, crossed pins provide increased strength,14,15 though numerous studies have not shown a clinical difference.16 The AAOS clinical practice guideline indicates that surgeons should considering avoiding medial pin placement, if possible, given adequate stability with lateral pins and potential risk of iatrogenic ulnar nerve injury with medial pin placement. Certain fracture patterns will necessitate a medial pin, such as an obliquely oriented fracture with limited proximal medial bone to gain bicortical purchase with lateral entry pins. Given the proximity of the ulnar nerve to the medial pin insertion site, great care must be taken to avoid injury. 

 

 

The most important aspect of medial pin placement is to not place the medial pin with the elbow flexed. The ulnar nerve has been shown to subluxate over the medial epicondyle in around 47% and dislocate anterior to the epicondyle in up to 18% of children when the elbow is flexed more than 90 degrees.17 Skaggs found a significant contribution of ulnar nerve injury in his review of pinning in 345 patients. There was a 4% rate of ulnar nerve injury when the medial pin was inserted with the elbow extended compared to a 15% rate when the pin was inserted with the elbow hyperflexed.11 

In addition to an extended position, a small incision can be used to allow a hemostat to spread soft tissues down directly onto the medial epicondyle to further protect the nerve. A milking maneuver can also be performed with the surgeon’s non-dominant thumb, pushing the soft tissues overlying the medial epicondyle posteriorly while the pin is percutaneously inserted. Oscillating the pin can further decrease the risk of injury to the nerve. 

A reasonable algorithm for treatment is to first place two lateral pins, which can be safely placed while the elbow is held hyperflexed and holding sagittal plane reduction. Once these pins are placed, stability is checked with fluoroscopy. If additional fixation is needed, either a third lateral pin or a medial pin can be placed. If the medial pin is needed, the two lateral pins should provide sufficient stability to allow the elbow to be extended for safe medial pin insertion. Again, never place a medial pin in a hyperflexed elbow.  

5. Be prepared for a Type IV fracture 

Leitch described a type IV fracture that indicates torn periosteum and multi-directional instability.18 This can occur as a result of the injury but can also result from over-aggressive manipulation of the fracture and subsequent tearing of the periosteum. Unfortunately, it is very difficult to predict a type IV fracture preoperatively with radiographs. Potential predictive factors include a flexion angulation of the distal fragment (most predictive), valgus angulation, lateral translation, and the pressence of osseous apposition between the proximal and distal fragments.19 

Without the posterior periosteum for stability, the fracture becomes unstable in both flexion and extension. This can make pinning very difficult and may cause you to adjust your technique and OR set-up. It is very common to use the image intensifier as the table for the procedure, with rotation of the shoulder to allow for a lateral to be checked. However, in these type IV fractures, there is a high risk for losing reduction while rotating the shoulder to check orthogonal images. In these situations, a floating hand table is helpful, allowing the C arm to move around a stationary elbow.  

 

 

 

 

 

 

References: 

  1. Suangyanon P, Chalayon O, Worawuthangkul K, Kaewpornsawan K, Ariyawatkul T, Eamsobhana P. Pediatric elbow measurement parameters: Evaluation of the six angles in inter- and intra-observer reliability. J Clin Orthop Trauma. 2019 Jul-Aug; 10(4): 792–796. 

  1. Baumann E, Beitrage zur Kenntnis der Frakturen am Ellbogengelenk. Unter besonderer Berucksichtighung der Spatfolgen I. Allgemeines und Fraktura supracondylica. Beitr Klin chir 1929;146:1-50. 

  1. Williamson DM , C J Coates, R K Miller, W G Cole. Normal characteristics of the Baumann (humerocapitellar) angle: an aid in assessment of supracondylar fractures. J Pediatr Orthop. Sep-Oct 1992;12(5):636-9. 

  1. Camp J, Ishizue K, Gomez M, Gelberman R, Akeson W.J Pediatr Orthop. Alteration of Baumann's angle by humeral position: implications for treatment of supracondylar humerus fractures. 1993 Jul-Aug;13(4):521-5. 

  1. Campbell CC, Waters PM, Emans JB, Kasser JR, Millis MB. Neurovascular injury and displacement in type III supracondylar humerus fractures. J Pediatr Orthop. 1995 Jan-Feb;15(1):47-52. 

  1. Shah AS, Waters PM, Bae DS. Treatment of the “pink pulseless hand” in pediatric supracondylar humerus fractures. J Hand Surg Am. 2013 Jul;38(7):1399-403. 

  1. Harris LR, Arkader A, Broom A, Flynn J, Yellin J, Whitlock P, Miller A, Sawyer J, Roaten J, Skaggs DL, Choi PD. Pulseless Supracondylar Humerus Fracture With Anterior Interosseous Nerve or Median Nerve Injury-An Absolute Indication for Open Reduction? J Pediatr Orthop. 2019 Jan;39(1):e1-e7. 

  1. Badkoobehi H, Choi PD, Bae DS, Skaggs DL. Management of the pulseless pediatric supracondylar humeral fracture. J Bone Joint Surg Am 2015 Jun 3;97(11):937-43. 

  1. Cheng JC, Lam TP, Maffulli N. Epidemiological features of supracondylar fractures of the humerus in Chinese children. J Pediatr Orthop B. 2001 Jan;10(1):63-7. 

  1. Scannell BP, Jackson JB 3rd, Bray C, Roush TS, Brighton BK, Frick SL. The perfused, pulseless supracondylar humeral fracture: intermediate-term follow-up of vascular status and function. J Bone Joint Surg Am. 2013 Nov 6;95(21):1913-9. 

  1. Skaggs DL, Hale JM, Bassett J, Kaminsky C, Kay RM, Tolo VT. Operative treatment of supracondylar fractures of the humerus in children. The consequences of pin placement. J Bone Joint Surg Am. 2001 May;83(5):735-40. 

  1. Srikumaran U, Tan EW, Belkoff SM, Marsland D, Ain MC, Leet AI, Sponseller PD, Tis JE. Enhanced biomechanical stiffness with large pins in the operative treatment of pediatric supracondylar humerus fractures. J Pediatr Orthop. 2012 Mar;32(2):201-5. 

  1. Srikumaran U, Tan EW, Erkula G, et al. Pin size influences sagittal alignment in percutaneously pinned pediatric supracondylar humerus fractures. J Pediatr Orthop. 2010;30:792–798 

  1. Larson L, Firoozbakhsh K, Passarelli R, et al. Biomechanical analysis of pinning techniques for pediatric supracondylar humerus fractures. J Pediatr Orthop. 2006;26:573–578. 

  1. Lee SS, Mahar AT, Miesen D, et al. Displaced pediatric supracondylar humerus fractures: biomechanical analysis of percutaneous pinning techniques. J Pediatr Orthop. 2002;22:440–443. 

  1. Dekker AE, Krijnen P, Schipper IB. Results of crossed versus lateral entry K-wire fixation of displaced pediatric supracondylar humeral fractures: A systematic review and meta-analysis. Injury. 2016 Nov;47(11):2391-2398. 

  1. Zaltz 

  1. Leitch KK, Kay RM, Femino JD, Tolo VT, Storer SK, Skaggs DL: Treatment of multidirectionally unstable supracondylar humeral fractures in children: A modified Gartland type-IV fracture. J Bone Joint Surg Am 2006; 88(5):980-985.  

  1. Mitchell SL, Sullivan BT, Ho CA, Abzug JM, Raad M, Sponseller PD. Pediatric Gartland Type-IV Supracondylar Humeral Fractures Have Substantial Overlap with Flexion-Type Fractures. .J Bone Joint Surg Am. 2019 Aug 7;101(15):1351-1356.