Orthopedic implant company study on biomechanics of fracture stability. The study has found out that mobilization of adjacent joints and the function of the musculature appears to be beneficial for fracture healing. Our researchers also quote that it is important to understand the motion at the fracture site and how it may be controlled to avert the happening of any kind of progressive deformities.
Our lab studies on the above-the-knee amputations connected well with our in vivo analysis. It also linked with the in vivo and in vitro studies of a similar nature conducted by other leading orthopedic surgical instruments experts. The studies have also demonstrated that the motion that takes place at the fracture site is elastic and is recoverable. This recovery happens once the load is relaxed.
Role of Surrounding Soft Tissues:
To understand the role of surrounding tissues, we will take into account a fracture brace that allows joint function and movement of the bone fragments. In such kinds of orthopedic implants & instruments such as spine implants, locking plates, etc, there is a measurable load borne by the implants, which is the brace in this case. Most of these loads are borne by the soft tissues.
They also allow small amounts of motion of the bone fragments. However, these movements are completely elastic which means are recoverable upon relaxation of the load. This elasticity is very important as it does not let the progressive deformity occur. Apart from load-bearing the soft tissues also control the amount of motion. This is related to the lit of the brace and also to the extent of soft tissue damage.
In our orthopedic implants company study, we found that the soft tissues have two major mechanisms for load deportment and provision of stiffness to the limb when included in a fracture brace.
The initial mechanism is related to soft tissue incompressibility. The muscle compartments act as fluid-like structure surrounded by an elastic fascia container (Facia is a band or sheet of connective tissue, primarily collagen, beneath the skin). An active load distorts the compartments of fixed volume (incompressible fluid).
This leads to changes in their shape which stretch the fascia boundaries. When a relatively rigid container, like a fracture brace, bound these compartments they can displace only under a load. This displacement happens only until they have filled all the gaps within the container (fracture brace). The muscle mass becomes rigid once this slack is taken up in the system. This rigidity occurs because the boundaries which are the walls of the brace, in this case, do not move. The elastic, fascial boundaries of each muscle return to their original shape once the load has been relaxed. This brings the fragments to their novel positions.
This initial mechanism of load-bearing in the soft tissues is imperative only during the early stages of management. These are the times when little healing has taken place in the bone or soft tissues.
During this initial stage, the fragments are loose and rely heavily on the soft tissues for support until callus forms. Finally, the soft tissues rely a lot on the degree of fit of the fracture brace. This is important in order for this mechanism to be effective.
This mechanism is only effective for short term fractures. Our orthopedic surgical instrument doctors state that for long-term use, this mechanism cannot be relied upon, since the dimensions of the soft tissues change with time through the loss of edema, atrophy, viscoelastic creep and fluid flow. Viscoelastic creep is a phenomenon that occurs when viscoelastic materials are subjected to a step constant stress. In such cases, these materials experience a time-dependent increase in strain and this is called viscoelastic creep.
During long term use, the fit of the brace also cannot be maintained indefinitely unless it is frequently adjusted. Loss of this fit generally results in an increased slack in the system. This increased slack further amplifies the displacement of the fragments which is required to produce mechanical equilibrium between the applied forces and the resistance of the tissues.
Our finest orthopedic implants experts experience that the "hydraulic" effect of the tissues is not responsible for the long-term maintenance of the length of the limb.
Shortening initially happens by the degree of soft tissue damage. However, with quick and dynamic loading, the soft tissue compartments act as incompressible fluids. This causes the volume of the tissue to be rigid.
In this orthopedic implant company study, we can conclude that hydraulics can control the motion of the fragments. It can also provide support for the intact tissues by escalating the stiffness of the limb. This probably protects them from further harm.
Orthopedic implants experts also think that hydraulics is also responsible for the control of motion of the fragments before the callus has developed. Further, it provides a significant degree of stiffness observed in loaded limbs with fresh fractures fit like with fracture braces.
On this note, we can summarize that hydraulics control certain rapid fluctuations in the system. But, it is equally important to understand that it does not control slow progressive changes in the system.