Wednesday, November 12, 2008

Agility Implant




source: http://www.myanklereplacement.com/binary/org/DEPUY/images/joint/ankle/new/Agility.jpg


The Agility ankle prosthesis was designed by Dr.Frank Alvine was first inserted in a patient in 1984 and it was the first ankle replacement to receive FDA approval. It is used in the majority of ankle arthroplasties performed in the United States. It is a semi-constrained, two part prosthesis which resurfaces the medial, lateral and superior articular surfaces of the ankle joint.

It consists of a titanium tibial component with sintered titanium beads and a cobalt-chromium talar component with sintered cobalt-chromium beads. A modular polyethylene inserts locks into the tibial component. The first ankles were all constructed of titanium but since 1989 cobalt-chromium has been used due to loosening of two talar components in the first 3 years. Thicker tibial component was also used start from the first time due to two broken components in the first 21 ankles implanted.

The tibial articular surface is larger compared to the talar component as this will allow axial rotation. The problem with this was that during the axial rotation, incongruent articulation will take place on the articulating surface. On the other hand, during the dorsiflexion and plantarflexion, congruent articulation can be achieved. When Agility prosthesis is inserted, it is combined with an arthrodesis of the tibiofibular syndesmosis using one, or more, which commonly was two screws.

Thursday, November 6, 2008

Ankle arthrodesis or Total ankle replacement?





It may be that you have known it or not, ankle arthrodesis is referring to fusion of our joint. This is including the process of gluing the related joint bones together using screw or any attachment methods that are available. This process will cause our joint to lose it normal upwards and downwards movement which surely disturb our daily walking ability. This will also increase the stress applied to the joint. Due to the fixation of the joint, it will leads to arthritis at the joint near to it that can cause more complication afterwards. This is one reason why Total Ankle Replacement becomes favorite among nowadays patients.

Experience will be needed in order to put in the implant nicely to avoid complication to the amputees in the future. Surgeon that have undergo many time of surgery will be better in completing the surgery process. This is important as different people will have different conditions and that is why there will be many variable to be considered during the insertion of the implant.

After receiving this implant, patients will be able to do their simple movements back. It is better to avoid activities that can overstress the joint. Patients can cycle, walk, hike, climb and even ski after the surgery and rehabilitation. They should avoid doing activities that can cause the joint to experience repetitive pounding and great stress such as running and heavy labor.

Good candidate for receiving this implant are those who are 50 years and over of age, not too heavy and not too active. Surgeons need to observe the receiver joint’s range of motion, having diabetes or not, nerve condition and bone quality. In some cases, arthrodesis is more suitable for patients as their range of motion of the joint is very small and they will less likely to realize the effect of arthrodesis to their joint’s movements. Diabetes and nerve condition need to be considered because they will affect the condition of the implant. Poor bone quality will disturb the performance of the implant and can cause loosening of the implant or broken of the bone.

After surgery, rehabilitation is very crucial so that patients can train they “new ankle joint”. After removing the surgery stitch, cycling and swimming can help to train the joint.