Anatomic safe zone for proximal ulnar fixation: a cadaver study.

OBJECTIVE: To study the location and characterization of the safe zone with respect to bony landmarks on volar surface of proximal ulna for the protrusion of various ulnar fixations. MATERIAL AND METHOD: The present study was done on 39 upper extremities from 20 embalmed human, adult cadavers. The average ages of the cadavers were 67.28 +/- 10.96 years (range from 40 to 82 years), 10 females, and 29 males. The safe zone dimensions, both in coronal and sagittal planes, were measured. RESULTS: The distance between median nerve and volar surface of proximal ulna in sagittal plane at 2 cm and 4 cm distal to tip of coronoid process were 0.99 +/- 0.15 cm (range from 0.76-1.32 cm) and 0.85 +/- 0.17 cm (range from 0.64-1.75 cm), respectively. The distances between the lateral border of the proximal ulna and medial border of the median nerve in coronal plane at 2 cm and 4 cm distal to the tip of the coronoid process were 0.95 +/- 0.19 cm (range from 0.66-1.36 cm) and 0.82 +/- 0.14 cm (range from 0.52-1.14 cm), respectively. CONCLUSION: Based on the present results, if intra-medullary screws or K-wire fixations were used, it should theoretically be long enough to reach their proximal ulna in order to bite into the cortical bone, but should not be so long as to cut out into its lateral part and, in the sagittal plane, the protrusion should not be longer than 0.92 cm. Orthopedic surgeons must remain vigilant with regard to any types of fixation in the upper extremity because the risk of neurovascular injury is high.

Vascular anatomy of the proximal fibula from embalmed cadaveric dissection.

OBJECTIVES: To study the vascular pattern of proximal fibula with use of embalmed cadaveric specimens. MATERIAL AND METHOD: The present study was done on 33 lower extremities from 19 embalmed human, adult cadavers. The average ages of the cadavers were 68.6 years (range from 36 to 98 years), 11 females and 8 males. The size and site of vessels around the proximal fibula were recorded. RESULTS: There were three main blood supplies of proximal fibular the epiphyseal artery, the lateral genicular artery, and the periosteal blood supply. They are anterior tibial recurrent artery and posterior tibial artery or artery of the neck of fibula posteriorly. Inferior lateral genicular artery was seen in all specimens (33/33). Among them, 42.4% (14/33) had a single artery with double accompanied veins. The average diameter of artery and veins were 1.71 mm (0.75-2.25), and 1.69 mm (1.30-2.10), respectively. The others were single artery and single vein. The average diameter ofartery and veins were 1.66 mm (0.65-2.14), and 2. 1 mm (0. 95-2.30) respectively. Anterior tibial recurrent artery was seen in 31 of 33 specimens (94%). The average size of artery and accompanying vein were 1.24 mm (0.8-2.1), and 1.86 mm (0.8-2.6), respectively. Posterior tibial recurrent artery was an inconsistent branch that appeared in only 11 of 33 specimens (33%). Artery of the neck of fibula appeared in 24 of 33 specimens (72.7%). The others were replaced by the predominant posterior tibial recurrent artery (7/33) and neither of them was found in two specimens. CONCLUSION: Based on the present results, the authors recommend preserving the epiphyseal blood supply, the inferior lateral genicular artery, and the periosteal blood supply for free epiphyseal transfer In addition, surgeons should pay attention to the variation of posterior periosteal blood supply because its variations will affect the viability percentage of proximal fibular epiphyseal transfer.

Anatomic safe zone of pin insertion point for distal clavicle fixation.

Clavicle fracture is the most common childhood fracture and one of the most common fractures in adults. Only some types of distal clavicular fractures, and dislocation of the acromioclavicular joint, require internal fixation. Many surgeons prefer closed pinning; however, the difficulty inserting many of the various kinds of pins from acromion into the medullary canal, of the distal clavicle, means the likelihood of iatrogenic complications from repeated drilling is heightened. The purpose of the present study was to establish what would be the optimum insertion point and direction for safe intramedullary pinning of the distal clavicle. Embalmed cadaveric shoulders (32) were studied. A bone window was created at the distal one-thirds of the clavicle, approximately 1.5 cm medial from the conoid tuberosity - as wide as could be freely, retrogradely drilled into the medullary canal of the distal clavicle. A 2.0-mm Kirschner wire was inserted until it penetrated the acromion. The point of emergence was recorded as ratio compared with the acromial width and length in coronal and sagittal planes, respectively. K-wire directions were measured as the angle between the K-wire and the reference line from the anterosuperior tubercle of the clavicle to the anterior angle of the acromion. The process was repeated until the acromion fractured 304 drillings were performed on 32 specimens. The length of the sagittal vs.coronal pin insertion point from the anterior vs. lateral borders of the acromion divided by its length vs. width averaged 0.325 +/- 0.04 and 0.397 +/- 0.09, respectively. The angle of the K-wire and the reference was 7.69 +/- 3.04 and 14.59 +/- 4.34 degrees in the coronal and horizontal planes, respectively. At 8 and 10 drillings survival was 0.72 (95%CI: 0.53-0.84) and 0.41 (95%CI: 0.24-0.57), respectively. The optimum pin inserting point for fixation of distal clavicle fracture and acromioclavicular joint dislocation is 32.5% and 39.7% of acromial length and width, respectively. If a 2.0-mm K-wire is used for fixation, drilling should not be repeated drilled more than 8 times to avoid sudden, high risk iatrogenic acromial fracture.