5 intramedullary nail application principles and surgical techniques!

Basic principles of intramedullary nailing

1. History of intramedullary nailing

In 1910, Lilienthal aluminum intramedullary nails were used to treat femoral shaft fractures.

In 1913, Schone used silver intramedullary nails to treat forearm fractures. 

Kuntscher (1900-1972) made great contributions to intramedullary nail fixation. 

The 1960s and 1970s were a period of rapid development of intramedullary nails. 

my country has been using them in large quantities since the 1990s.

2. Open reduction and closed reduction

1. Limb fractures can be surgically reduced under direct vision or closed under X-ray monitoring.

2. Open reduction fracture healing time is relatively long, intraoperative bleeding is more, and open reduction further destroys the blood supply to the fracture end.

3. It is recommended to use closed reduction as much as possible. A traction reducer can be used, or a small incision can be made on the fracture plane to pry and reduce, thereby minimizing interference with the blood supply to the fracture end.

4. For closed reduction failure, bone fragment flipping or piercing surrounding tissues, and large displaced fracture fragments, surgical open reduction can be used.

3. Fixation mechanism of intramedullary nail

1. The method of intramedullary nail internal fixation is symmetrical central internal splint fixation.

2. The fixation of fracture by intramedullary nail is stress-distributing fixation, not stress-shielding fixation, which is conducive to the shaping of callus.

3. Central fixation is theoretically superior to cortical external fixation, which can reduce the force arm, reduce the incidence of valgus angulation and internal fixation failure.

4. Intramedullary nail fixation provides the basis for closed reduction or limited open reduction.

4.Advantages of intramedullary nails

1. Fewer complications

2. Expanded scope of surgical indications

3. Firm fixation

4. Early joint function training

5. Early weight bearing

6. Can be used in combination with other internal fixation

Basic Types and Techniques

1. Locking and non-locking intramedullary nails

2. Dynamic and static locking intramedullary nails

3. Medullary expansion and non-medullary fixation techniques

4. Open and closed fixation techniques

Interlocking and non-interlocking

Ordinary intramedullary nails have poor axial stability and relatively low torsional strength, but they have a certain elasticity and can recover after deformation, causing only a small amount of intrabone sliding.

Interlocking intramedullary nails have better anti-rotation and anti-compression effects, good fixation stability, and conform to the principle of biological fixation. They are widely used in long bones of the limbs. Especially for multi-segment and comminuted fractures, they have better stability than ordinary intramedullary nails.

Dynamization of static fixation

Static locking intramedullary nails produce very little stress masking and are currently mostly advocated for non-routine action of dynamization.

For fractures that have not healed at 6 to 8 months postoperatively, in situ bone grafting or replacement of expanded intramedullary nails with dynamization is commonly used.

Dynamization may be used as a means to promote fracture healing. It is not recommended routinely because it may lead to limb shortening and rotational deformity.

Marrow expansion and non-marrow expansion

Marrow expansion can insert intramedullary nails with larger diameter and greater strength, which is conducive to early functional training and reduces the rate of broken nails.

Marrow expansion can produce a large amount of bone debris with osteoinductive effect, which is conducive to fracture healing.

Marrow expansion will damage the blood supply of nutrient vessels and endosteal membrane, but blood vessels can regenerate along the cavity of intramedullary nails. Marrow expansion can also increase blood circulation in surrounding soft tissue muscles, thereby promoting fracture healing.

Marrow expansion relatively increases the chance of infection and embolism, and should be used with caution for open fractures, multiple injuries, and complex injuries.

Advantages of medullary expansion

① After medullary expansion, the contact area between the intramedullary nail and the bone increases, which improves the stability of fixation. 

② After medullary expansion, a larger diameter intramedullary nail can be used, which increases the strength of the intramedullary nail and reduces the rate of broken nails. 

③ Bone debris after medullary expansion can induce new bone formation, which is conducive to fracture healing.

Compared with medullary expansion intramedullary nails, non-expanded intramedullary nails have the following advantages

① Shorter operation time and less bleeding. 

② Less interference with endosteal blood flow in cases with severe soft tissue injuries.

Application of intramedullary nail

Humeral interlocking intramedullary nail

Indications for humeral nails

The indications for humeral interlocking intramedullary nails in the treatment of humeral shaft fractures are: fractures with vascular and nerve damage, multiple injuries, unstable fractures, pathological fractures, and proximal humeral fractures.

The range that can be fixed is from 2cm below the humeral head to 3cm above the olecranon fossa. You can choose to fix it from the shoulder with an antegrade intramedullary nail or from the elbow with a retrograde nail.

Characteristics of humeral nails

The surgical fixation methods for humeral shaft fractures are basically plate fixation and intramedullary nail fixation.

Plate fixation has strong anti-rotation and anti-bending properties and is firmly fixed, but the surgical trauma is large, the probability of infection is high, and the radial nerve is easily damaged.

Modern humeral interlocking and self-locking nails overcome the shortcomings of ordinary intramedullary nails such as axial instability, poor rotation control, and the need for additional fixation, so that the fracture is firmly fixed, the blood loss is small, the soft tissue stripping is less, and the medullary expansion is equivalent to local bone transplantation, the load is evenly distributed, the callus appears early, and functional exercise can be started after surgery.

Femoral interlocking intramedullary nail

Indications for femoral interlocking nails

All types of fractures 2cm below the trochanteric vertebra and more than 9cm from the knee joint.

Old fractures of the middle part of the femoral shaft.

Patients with failed plate internal fixation.

Features of femoral interlocking nail

Mechanical advantages

The force arm of femoral interlocking intramedullary nail for fixing fractures is longer than that of steel plates, and the force is evenly distributed on the central axis of the entire bone, which is not easy to bend and deform.

The locking nails at both ends of the intramedullary nail make the bone form a whole from top to bottom, and the locking nails at the distal end can reduce the torque arm of the intramedullary nail in the bone, prevent shortening and rotation, and achieve maximum stability and firmness for fracture fixation.

Gamma Interlocking Intramedullary Nail

Gamma nail indications

Applicable to various types of peritrochanteric fractures, especially subtrochanteric fractures.

Extended Gamma nail (reconstruction nail) indications

high subtrochanteric fractures, trochanteric combined with femoral shaft fractures.

Advantages of Gamma nail

Developed by combining sliding hip screw with intramedullary nail technology, the main nail is closer to the inside of the medullary cavity than the dynamic hip plate, so the Gamma nail conducts the patient's weight closer to the femoral calcar than the dynamic hip plate, increasing the mechanical strength of the implant. For subtrochanteric fractures involving medial cortical comminution, the Gamma nail avoids the need for fracture anatomy reconstruction, so it is beneficial for intertrochanteric fractures or subtrochanteric fractures.

Retrograde intramedullary femoral nailing

Indications of retrograde femoral nails

Mainly used for supracondylar femoral fractures, including supracondylar comminuted fractures and intercondylar "T" and "Y" comminuted fractures involving the articular surface.

It can also be used for femoral fractures below the isthmus of the femur.

Femoral shaft, supracondylar femoral, and intercondylar fractures within 20CM from the knee joint.

Those who have failed plate fixation.

Characteristics of retrograde femoral nailing

Supracondylar femoral fracture is a serious fracture with difficulty in firstly, reduction and secondly, strong internal fixation. There is a high incidence of complications such as fracture non-union and delayed healing.

Retrograde interlocking intramedullary nailing is a commonly used method to treat distal femur fracture in recent years, which has good mechanical stability, can effectively control the posterior displacement and rotational displacement of the distal end of the fracture, and helps in the early joint movement.

Supracondylar combined femoral stem fracture is fixed with lengthened supracondylar intramedullary nailing, which solves the problem that is difficult to be solved by interlocking intramedullary nailing of the femur. The instrument is simple to operate, accurate in positioning, reliable in fixation, and the patient can perform early functional knee exercises after surgery.

Tibial interlocking intramedullary nails

Indications for tibial nailing

Stable fractures in the middle 1/3 of the tibia: transverse fractures, short oblique fractures, pseudarthrosis.

Unstable fractures within 60% of the length of the middle tibia: fractures near the metaphysis, long spiral fractures, segmental fractures, comminuted fractures, fractures with bone defects.

Characteristics of tibial nailing

Interlocking intramedullary nailing of tibia is mostly used for mid tibia fractures.

Although it can also be used for proximal and distal tibia fractures, the complication rate is higher, malunion occurs more often, the fracture end has ≧1cm of movement in 1/2 of the cases, and 1/4 of the fixation fails.

Literature reported better outcome of distal tibia fracture than proximal tibia fracture after routine fixation of fibula.

Surgical techniques

Preoperative preparation of special equipment

Orthopedic bed (traction bed) or standard fluoroscopic surgical bed; retractor; image intensifier.

Correct selection of intramedullary nail length for preoperative endoprostheses

Radiograph

contralateral limb length measurement

Intramedullary nail diameter

x-ray isthmus width

Intramedullary nail length measurement

1.Translucent ruler determination under C-arm machine

The distal and proximal ends of the bone were on the centerline of the ray; the ruler was parallel to the diaphysis.

2.Length measurement according to body surface markings

Femur: tip of greater trochanter → lateral knee space or superior pole of patella; tibia: medial-lateral knee space → anterior aspect of ankle joint in dorsiflexion of foot.

Intramedullary Nail Insertion Technique - Entry Point Approach

Longitudinal axis of the medullary cavity in a straight line

Not too close to the entry point

Appropriate length: dilated - long; undilated - short

(Indirect confirmation of entry point; no pulp dilation, no soft tissue protection required)

Parallel femoral intramedullary nail entry point

Preparation of the entry point for a parallel femoral intramedullary nail

Hip flexion and adduction

Longitudinal incision proximal to the greater trochanter

Not too far back

Placement of the guide pin

Placement of the soft tissue shield

Retrograde femoral intramedullary nail entry point

30° knee flexion

Long axis of the guide pin in the same direction as the medullary cavity of the distal femoral stem

Insertion of the Kirschner pin into the distal femur via the patellar ligament through the protective sleeve: orthogonal - middle of the intercondylar fossa of the femur; lateral - Blumensaat's line

Starting point of PCL without injury

Parallel tibial intramedullary nail entry point

On the centerline of the medullary cavity

Anterior margin of tibial plateau

As high as possible without damaging the plateau

Maximum knee flexion

Incision tibial tuberosity-inferior pole of patella along the medullary cavity

Open the medullary cavity: guide pin at 15° to the sagittal plane of the longitudinal axis of the tibial stem

Position of the image intensifier

Marrowing techniques

Electrically powered reduction

fresh fractures

Manual reduction

old fracture with pseudoarthrosis, sclerosis in the medullary cavity

No tourniquet under inflation

blood circulation is the best coolant

Repositioning techniques

Parallel femoral intramedullary nailing

Reasons for difficulty in restoring femoral fractures

Thick soft tissue wrapping does not allow direct access to the bone

Needle entry point cannot be visualized directly

Hip joint adduction → iliac fascia tension → fracture shortening

Tibial fracture reduction

Manipulation

Mostly subcutaneous and easy to palpate

Stabilized fracture - mid or distal A and B type fracture

Oblique fractures - overkill

Intramedullary nailing→displacement tools

Ancillary reduction measures

Point reduction forceps

tibia; percutaneous or wound use

Large retractors (braces)

delayed reduction; limb shortening

Temporary Schanz screws

① Femur, tibia

② As close to the fracture line as possible

③ Proximal fracture single cortical use

④Use a universal chuck with a T-handle for easy maneuvering

Poller nail

①Metaphyseal fracture (correcting the line of force, stabilizing the restoration, restoring the operation)

② oblique fracture of distal tibia or femur (shear stress → pressure)

③ Poorly positioned intramedullary nails enter the old medullary channel during secondary surgery

④ Poor point of entry, poor proximal fracture alignment (screw placed perpendicular to the possible displacement of the endoplant)

Extra wide tourniquet

① tibia

② supplemented by traction or retractor

③ Use with caution in severe soft tissue injuries

④ Keep it short

⑤ Prohibit medullary expansion in the inflated state

Nail locking sequence: distal then proximal

Advantages

ease of knockback, compression of fracture breaks; elimination of separation; reduction operations.

Reduction techniques for delayed & nonunion surgery

Problems that may be encountered with delayed surgery

Axial deformity (shortening, angulation and or displacement)

Growth in of granulation tissue

Early bone scabs

Sclerosis of fracture breaks with closure of the medullary cavity

Osteoporosis

Possible intraoperative problems

Deflection of the expander and the intramedullary nail → intramedullary nail penetration of the cortex

Angular deformity → retractor

Dislocation of severed ends → Poller's nail, plate fixation

Methods to prevent abnormal force lines

Proximal - correct entry point

Distal - intramedullary nail in the center of the medullary cavity

Complications of Intramedullary Nailing

★Infection

★Nerve damage

★Distorted healing of fractures

★Medical Fractures

External rotation, torsion, valgus, internal rotation, angulation

★Adjacent joint pain

★Fat embolism

★Heterotopic ossification

★Pulmonary embolism

★Re-fracture

★Thrombosis

★Joint stiffness

★Non-union of fracture, bone nonunion

★Internal fixation failure

★Limb shortening

★Other

Complications--Infection

1.Early on, open fractures were considered a contraindication to intramedullary nailing.

2.The incidence of postoperative infection in open fractures depends on the status of soft tissue injury and contamination

The incidence of infection after open fracture depends on the state of soft tissue injury and contamination as well as the manner in which the soft tissue is managed.

3.Thinner intramedullary nails increase the chance of infection; non-expanded locking intramedullary nails fixation is relatively poor, and the bone ends have

The non-expanded locking intramedullary nail fixation is relatively poor, with microscopic movement of the broken end of the bone as well as residual cavity, which is easy for bacterial growth.

4. The use of expanded and limited expanded medullary fixation not only improves the stability of the fracture, but also avoids the creation of a dead space.

Fat Embolism Syndrome

1.The incidence of FES of long tubular bone fractures is 0.5% to 2%.

2. Expansion of the medulla and non-expansion of the medulla has no significant effect on pulmonary ventilation.

3.When expanding the medulla, the technique should be gently kneading, avoiding too much force and rough operation.

4.the current diagnosis of FES still adopts the criteria proposed by Gurd in 1974, and the treatment after diagnosis will delay the best time for treatment and may have serious consequences.

Delayed fracture healing and bone nonunion

Various factors affect fracture healing after intramedullary nail fixation, and the causes may be analyzed as follows.

1.soft tissue embedded in the fracture end

2. Separation of transverse fracture ends

3. Older age of the patient

4. Open fracture, serious soft tissue injury, serious local hemodialysis or infection.

5. Poor intramedullary nail fixation

6. Combined diabetes mellitus or other consumptive diseases.

Medical Fractures

Medically induced fractures are mainly secondary fractures caused by improper manipulation during intramedullary nail fixation.

Intraoperative attention should be paid to

1. Inaccurate selection of the nail entry point may lead to proximal fracture.

2. Do not forcefully push in the expansion of the medulla.

3. The entrance of pulp expansion should be in the same direction as the direction of nail insertion.

4. Do not use force when inserting intramedullary nails into the distal end.

Pain in neighboring joints

1. Placement of an intramedullary nail involves soft tissue and even the joint capsule in the vicinity of at least 1 joint.

2. The tibial plateau is connected to the anterior edge of the medial meniscus by the transverse knee ligament and forms a safe zone above the tibial tuberosity up to this point. If the nailing point is too close to the top or the diameter of the intramedullary nail is too large, it can cause damage to the intra-articular structures, resulting in postoperative knee pain.

3. Proximal protrusion of intramedullary nail and heterotopic ossification are the main causes of hip pain after femoral intramedullary nail surgery.

4. Proximal protrusion of intramedullary nails, proximal locking nail irritation and rotator cuff interference are the main causes of shoulder pain after humeral intramedullary nailing.