Correction of Excessive Tibial Plateau Angle and Limb Shortening in a Juvenile Dog Using a Hinged Circular Fixator Construct and Distraction Osteogenesis

An 18-week-old Rhodesian Ridgeback puppy that was hit by a car sustained a Salter-Harris type III fracture of the left proximal tibial physis and ipsilateral diaphyseal femoral and tibial fractures. The diaphyseal fractures were successfully stabilized with bone plate fixation. Premature closure of the caudal aspect of the proximal tibial physis, secondary to the proximal physeal fracture, resulted in an excessively high tibial plateau angle (TPA) of 50° with a limb length discrepancy of 13% by 24 weeks of age. The deformity was addressed by performing a proximal tibial osteotomy and subsequent distraction osteogenesis to reduce the TPA while concurrently lengthening the crus. A radial osteotomy was performed in the proximal metaphyseal region and the hinged fixator was applied. Distraction was initiated the day following surgery at a rate of 1 mm per day as measured along the caudal cortex of the tibia with a rhythm of three distractions daily. Distraction was terminated 19 days postoperatively. Sequential distraction of the osteotomy resulted in 17 mm of tibial lengthening and a final TPA of 3°. The fixator was removed 52 days after application. Complications included wire tract inflammation involving the wires securing the proximal segment and a calcaneal fracture which required bone plate stabilization. The left pelvic limb was only 8% shorter than the right pelvic limb and the dog had only a subtle lameness 12 months after surgery. The hinged circular fixator construct allowed for both the reduction of the TPA and limb segment lengthening in this dog.

Effects of the Elbow Flexion Angle on the Radial Nerve Location around the Humerus: A Cadaver Study for Safe Installation of a Hinged External Fixator

Background: This study aimed to investigate whether the distance between the radial nerve and rotational center of the elbow joint when observing from the lateral surface of the humerus changes according to passive elbow joint flexion for safe external fixation with a hinged fixator of the elbow joint. Methods: Twenty fresh-frozen cadaveric arms were dissected. The points where the radial nerve crosses over the posterior aspect of the humerus, crosses through the lateral center, and crosses over the anterior aspect of the humerus were defined in the lateral view of the elbow joint, using fluoroscopy, as R1, R2, and R3, respectively. The distances between the rotational center and each point on the radial nerve were measured when the flexion angle of the elbow joint was 10°, 50°, 90°, and 130°. Results: The distances between the rotational center and R1, R2, and R3 were 118 mm, 94 mm, and 65 mm, respectively, when the flexion angle was 10°; 112 mm, 93 mm, and 74 mm, respectively, for 50°; 108 mm, 93 mm, and 77 mm, respectively, for 90°; and 103 mm, 94 mm, and 83 mm, respectively, for 130°. The distance between the rotational center and R2 was constant regardless of the flexion angle. With elbow joint extension, the distances between R1 and R3 increased; the safe zone, a region where the radial nerve would not be located on the humerus, was the smallest in extension. When the elbow joint was flexed, the distances between R1 and R3 decreased; the safe zone was the largest in flexion. Conclusions: This study showed that the radial nerve location on the humerus varied based on the flexion angle of the elbow joint; the safe zone may change. A half-pin can be likely inserted safely, avoiding the elbow joint extension position.

Additional external hinged fixator after open repositioning and internal fixation of acute elbow instability in non-compliant patients

This is a retrospective analysis of the clinical and radiological outcome in 11 patients with complex acute posttraumatic elbow instability after dislocation. These patients had also been treated with a hinged external fixator after open reduction, capsular and ligamentous reconstruction and internal fixation, because of an expected diminished compliance, to avoid a secondary dislocation of the internal fixation. Concentric stability and a sufficient range of motion of the elbow joint were achieved in all cases. Non-compliant patients were classified by the surgeon as not compliant or not able or not willing to cooperate post-operatively for various reasons, such as alcoholism, drug abuse, mental disability, cerebral trauma or senile dementia. Non-compliant patients had undergone open reduction and internal fixation of an acute posttraumatic unstable elbow. The addition of a hinged external fixator allows early intensive mobilization, and can protect and improve the clinical outcome after these complex elbow injuries. This evaluation remains, of course, largely subjective and decision making is not easy because in most cases, the patient was not known before surgery. Thus, the only patient exclusion criteria in this study was surgeon classification as “compliant”.