Distal Femur Fractures & Nonunion- Use of Fibular Graft

The physician may be faced with some complex distal femur fractures or nonunion where the bony stock is not adequate or the fixation may have failed. It may also be a situation where a bone graft cannot be obtained from the patient. In some of these cases, I use an intramedually fibular graft in addition to plate fixation. The intramedullary fibular graft technique can be used in: complicated cases, comminuted fractures with osteoporosis, failure of traditional method of fixation, complex nonunion, and complex supracondylar periprothetic fractures.

How do you perform the technique?

The physician must find the starting point, which is the center of the intercondylar notch just

superior to the Blumensaat’s Line. The physician will insert a guide wire after reduction of the fracture. Then, the physician will ream over the guide wire to the appropriate size of the fibular graft, which you may need to fashion slightly. The physician needs to be sure to change the beaded guide wire to a smooth one and put the fibular graft through the guide wire into the medullary canal across the fracture of the nonunion. If the medullary canal of the fibula is small and it will not go through the guide wire, then place the fibular graft free hand. The physician should be sure that the fibular graft is not prominent through the joint. Next, fix the fracture or nonunion with a plate preferably a locking plate. You can augment the fixation with bone graft, allograft, or bone graft substitute. This procedure can also be helpful in periprosthetic fractures of the distal femur. If the prosthesisi is stable, you will do fixation of the fracture of the nonunion. It will be ideal to use a plate fixation after insertion of an intramedullary fibular graft, especially if the bony stock is very poor and if you can pass the fibular graft through the femoral component.

Isolated Fibular Fractures

Fibular fractures are usually associated with a complex injury, however they can be an isolated fracture. Complex injuries where a fibula fracture can occur include: fracture of the fibula and tibia, ankle fracture, pilon fracture, and Maisonneuve fractures.

Maisonneuve fractures involve a fracture of the proximal fibula associated with an occult injury of the ankle. Isolated fibular fractures are rare and usually the result of direct trauma. The fibula carries about 15% of the axial load and is the site of muscle attachment for the peroneus muscles and the flexor hallucis longus muscle. Check the patient who has a fibular fracture and no other fracture involving the tibia to rule out a possible Maisonneuve fracture, especially if there is no history of direct trauma to the leg. A high index of suspicion is necessary to diagnose and treat this injury. For high fibular fractures, the physician should look for signs of syndesmotic injury. Syndesmotic injury may include an unexplained increase in the medial clear space or the tibiofibular clear space is widened (should be less than 5mm). The x-ray will show the fracture to be rotational or oblique. Maisonneuve fractures require surgery to fix the syndesmosis.

Treatment will consist of reduction and fixation. It is important to determine if the injury is a Maisonneuve fracture or an isolated fibular fracture. An isolated fibular fracture will not need surgery.

Congenital Dislocation of the Knee

Congenital Dislocation of the knee is rare and may occur due to a contracture of the quadriceps. This condition usually occurs in patients with myelo, arthrogryposis, or Larsen’s syndrome. The patient with a congenital dislocation of the knee may have developmental dysplasia of the hip (DDH) and club foot. On examination, the patient will have a hyperextended knee at birth. They may have their foot placed against their face and there will be limited flexion at the knee. The patient may have a dimple or skin crease at the anterior aspect of the knee. You must examine the hip to rule out ipsilateral hip dislocation. 50% or more patients will have hip dysplasia. The etiology is not known; however, it could be due to fetal positioning or congenital absence of the cruciate.

There are grades, or a spectrum, for this deformity. Grade I deformities are referred to as Severe Genu Recurvatum, and the knee is hyperextended. If the range of passive flexion is more than 90°, it is considered to be a simple recurvatum. Grade II deformities are identified by subluxation with a range of 30-90° in passive flexion. Grade III deformities are complete dislocations with a range of passive flexion being less than 30°.

Congenital dislocation of the knee will take priority over treatment of hip dysplasia or club foot. The Pavlik harness and club foot cast will require knee flexion, so the physician will need to treat the knee dislocation first. With Grade I deformities, the initial treatment will be stretching of the knee and serial casting with the knee in flexion. In serial stretching and casting, the goal is to obtain at least 90° of flexion and reduction of the deformity over the course of several weeks. The physician should avoid pseudo-correction through an iatrogenic fracture of the proximal tibial physis. The prognosis is usually good if reduction is achieved without surgery. With Grade II deformities, if the infant is less than 1 month old, you will do serial casting first followed by percutaneous quadriceps recession, especially if the flexion is less than 90°. In Grade III deformities, a V-Y quadricepsplasty with above the knee cast is done in Grade III (frank dislocation), especially if nonsurgical treatment fails to reduce the tibia on the femur.   The result of open surgery is better when it is done in children younger than 6 months. In general, open reduction is reserved for children who did not respond to stretching and cast immobilization. It is important that the hip dysplasia is recognized and the knee dislocation is corrected early. This will help in early reduction of the hip.

Martin-Gruber Anastomosis

Martin-Gruber Anastomosis is median to ulner anastomosis in the forearm. It occurs through a communicating nerve branch between the median nerve and the ulnar nerve in the forearm. This connection carries motor nerve fibers. It can be confusing clinically and also on an EMG. It has a clinical significance for understanding the median nerve lesions and carpal tunnel syndrome. The axons will leave the median nerve or the anterior interosseous nerve crossing through the forearm to join the main trunk of the ulnar nerve, innervating the intrinsic muscles of the hand. The lesion above the communicating branch will affect the median nerve muscles. A lesion below the anastomosis (connecting branch) will not affect the median nerve muscles, it will spare the thenar motor intrinsic muscles of the hand. An isolated ulnar nerve lesion at the elbow will produce an unusual pattern for intrinsic muscle paralysis. Martin-Gruber Anastomosis is the most common anastomosis anomaly between the two nerves. In cases of nerve lesions of the median or ulnar nerve, this anastomosis serves as a conduit or an alternative innervation of parts of the hand and the forearm (it is really a detour). This can be a good explanation of difficult challenges, especially in the differential diagnosis. Incidence is high (about 15%). The physician should factor Martin-Gruber anastomosis into the differential diagnosis and the diagnosis.

If the communicating nerve arises from the anterior interosseous nerve, then a patient with anterior interosseous nerve palsy may present with hand intrinsic weakness, normally supplied by the ulnar nerve. Damage of the ulnar nerve at the wrist will lead to severe deficit of the intrinsic hand function greater than expected. There are other anastomoses available and reported as well as many variations that are possible.

There are three common anastomoses:

1. Ulnar to median anastomosis in the forearm-reverse of Martin-Gruber (Marinacci anastomosis)
2. Ulnar to median anastomosis in the hand (Riche-Cannieu anastomosis)
   1. Connection between the deep branch of the ulnar nerve and the recurrent branch of the median nerve
   2. It carries motor fibers and this anastomosis usually occurs in the region of the thenar and adductor pollicis muscles.
3. Berrettini Anastomosis
   1. Communication between the digital nerves (sensory nerves) arising from the ulnar and median nerves in the hand
   2. Most common nerve anastomosis pattern

When the examination does not make sense and it is confusing, you can consider Martin-Gruber anastomosis.