الفهرس 
SURGICAL ANATOMY OF THE HUMERUSOnly 14 pages are availabe for public view
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Abstract
Fractures of the humeral shaft are relatively common injuries that represent approximately 3% of fractures in adults and children.
Most humeral shaft fractures can be managed successfully non-operatively in a functional brace following short-time usage of a coaptation splint or hanging arm cast. This is based on the fact that the arm can tolerate a good amount of malunion with no significant functional deficit owing to the wide range of shoulder and elbow joint mobility.
Operative intervention is indicated in special circumstances including inability to achieve satisfactory position and alignment by conservative measures, and in some fracture patterns.
The surgeon may choose from a variety of options including: external fixation, compression plating, and intramedullary nailing either using multiple flexible nails or the interlocking humeral nail. Optimal results depend on matching your choice with the needs of the patient.
External fixation is infrequently used and generally reserved for severely comminuted fractures with bone loss, severe open fractures, and in cases of infected non-union.
Osteosynthesis with a compression plate remains the gold standard of surgical treatment of humeral shaft fractures with union rates from 95-97%. However, the need for an expert surgeon in plate application techniques, and the relatively higher risk of neurovascular iatrogenic injuries should be in mind. Moreover, additional challenges exist to achieve stable fixation with poor bone quality as in cases of osteoporosis.
Interlocking humeral nail is a good choice in some circumstances including segmental fractures, fractures in osteopenic bone, and in some pathological fractures. However, several complications have been reported with their application including relatively higher rates of non-union, iatrogenic comminution especially in narrow canal diameters and more commonly the shoulder pain and malfunction that reaches up to 16-37% of patients in some recent studies. Moreover, the interlocking nail cannot be used with open physeal plate, and in the presence of gross humeral deformity.
Flexible nails are low-cost implants that have been used a long time ago in fixation of long bone fractures following the description of the Rush brothers IM pinning system since 1927.
Their usage almost completely disappeared from the therapeutic field due to incidence of rotational malunion and nail migration. In the late 1970s, flexible nailing re-appeared with the idea to tailor a system of internal fixation for children’s specific needs. Gradually, the idea of using two elastic nails with opposing curves took shape, and the term elastic stable intramedullary nailing was introduced, and the indications of using flexible nailing in diaphyseal fractures was expanded dramatically as early as 1980.
Fracture healing in flexible nailing is achieved by secondary bone union. On the contrary to rigid fixation, elastic internal fixation needs some degree of relative movement to promote formation of the external callus, which is the physiological callus that forms most rapidly and has the highest biomechanical strength.
Several flexible intramedullary devices are available such as: Ender pins, Hackethal nails and Rush rods (these are stainless steel nails), also the Nancy nails (made of titanium). We can say that both stainless steel and titanium are sustainable for children, whereas stainless steel is definitely the best choice in adolescents often involved in intense activities.
Flexible intramedullary devices are used in the treatment of acute humeral shaft fractures when operative management is indicated. Their usage is preferred in children where injury to the physes is avoided, and in multiply injured adult patients owing to their ease of application and speed of insertion. Recent researches support flexible nailing as a treatment of choice for juvenile bone cysts of the long tubular bones in childhood.
Depending on the location of the fracture, a flexible nail can be easily applied through a proximal or a distal portal. Fractures of the proximal and middle thirds of the shaft should be nailed through a distal entry point(retrograde nailing), and fractures of the distal third are better fixed through a proximal entry point(antegrade nailing). This minimizes the risk of extending the fracture and losing the three-point fixation necessary for these implants.
The postoperative is simple as good stability of the construct generally makes complete immobilization unnecessary. A simple sling is worn. When pain and swelling are controlled about 2–3 days after surgery, the patient is encouraged to do pendulum exercises of the shoulder with advancement to passive range-of-motion exercises of the elbow and shoulder to be repeated as tolerated.
Clinical union often occurs between 6–12 weeks postoperatively (average 9 weeks) depending on the age and bone quality of the patient. In adults, the nails are removed at 6 to 12 months after solid union of the fracture is achieved. In children, prolonged implantation of the nails is not recommended as they will be all the more difficult to remove, so it is advisable to remove the nails as soon as bone union is obtained between the fourth and the sixth postoperative month. The removal procedure is performed on a day-patient basis using the initial incision.
The flexible intramedullary nailing of the humerus is a low morbidity functional surgery, economic, with simple minimally invasive operative technique, with good results, and minimal or no complications.