Technique Spotlight: Minimally Invasive Plate Osteosynthesis in Humeral Shaft Fractures

Indications

Surgical treatment of humeral shaft fractures is indicated after inadequate closed reduction, polytrauma, open fractures, bilateral injuries, and ipsilateral forearm fractures requiring surgical intervention. Excessive body mass index (BMI) or habitus forces the humerus into an unacceptable varus posture in a patient who otherwise would be best treated initially in a functional brace (i.e., smoker, diabetes).

It should be noted that the majority of humeral shaft fractures will meet criteria for nonoperative, conservative management. These fractures tolerate a great deal of deformity and malunion before becoming functionally limiting. This includes ≤20 degrees of anterior angulation, ≤30 degrees of varus/valgus coronal alignment, and ≤3 cm of shortening. Because the humerus possesses such anatomic forgiveness, establishing rigid stability with absolute anatomic reduction of the fracture site is not critical. Furthermore, an overly aggressive soft tissue dissection in an effort to perfectly align the fracture may be detrimental to the healing of the fracture.

When surgical intervention is indicated, traditional open reduction with internal fixation through an extensile approach has been the gold standard. However, this surgical approach is also associated with increased operative time, risk of triceps denervation, as well as increased risk of iatrogenic radial nerve injury. Minimally invasive plate osteosynthesis (MIPO) is a technique where plate fixation is achieved through minimized incisions, submuscular placement, and avoidance of fracture site exposure. This is an attractive option that minimizes soft tissue disruption while preserving humeral shaft union rates. Historically, intramedullary nailing (IMN) has been an attractive option due to its ease of application through a minimally invasive technique; however, the attendant rotator cuff morbidity and increased risk of neurovascular injury with distal interlocking screw placement have led to a decline in its use.

There have been numerous studies that have compared the various surgical fixation techniques for humeral shaft fractures. In direct comparison studies, MIPO compares favorably with ORIF (open reduction internal fixation) and IMN. MIPO also carries a high union rate with decreased risk of iatrogenic radial nerve injury compared with ORIF and IMN. MIPO plating, with less triceps dissection and soft tissue disruption, can allow for early elbow motion and weight-bearing which is especially beneficial in the polytrauma scenario. This technique has also been shown to decrease operative time and blood loss when compared with ORIF. ^, While ORIF aims for rigid fixation and primary bone healing, the goal of MIPO fixation is relative stability and secondary bone healing with a long plate “working length.” It utilizes intact soft-tissue envelopes and indirect reduction techniques to achieve acceptable alignment, minimizing disruption of developing callus and periosteal vascularization. This technique is similar to the goals of an IMN technique but avoids the shoulder complications (rotator cuff injury, shoulder pain, etc.) seen in humeral nailing.

There are specific indications and contraindications for MIPO. It is indicated for diaphyseal humeral shaft fractures ( Fig. 34.1A–B ) from the surgical neck of the humerus to 10–12 cm proximal to the distal articular surface. There is no role for MIPO plating with intra-articular fractures where an anatomic reduction is necessary. Contraindications include pathologic fractures, active infection, soft-tissue injuries that preclude appropriate incisions, vascular injury requiring exploration and repair, and radial nerve dysfunction. The latter two conditions require extensive exposure, thereby limiting the benefits of the minimally invasive technique. Radial nerve palsy in a blunt, closed, or gunshot wound injury does not absolutely preclude the MIPO technique, although once the decision has been made to operate, most upper extremity surgeons favor identifying and establishing the degree of nerve injury to predict and guide postoperative expectations and management.

A relative contraindication remains surgeon comfort and level of experience with this technique.