ROTATION PLASTY PROSTHESES, A PROSTHETIST'S PERSPECTIVE

Eugene Banziger, CPO (c)


Introduction:

Patients who have become victims of Osteosarcoma and as a result had to undergo a rotation plasty procedure are not the majority of the amputee population. This procedure, however, needs to be performed for certain sarcomas of the lower limb. Due to the low number and distribution of those patients, only a limited number of Prosthetist's are exposed to this patient group, (there are less rotation plasty patients then prosthe-tists). This results in limited experience for individual practitioner unless he or she may has several clients of this type of. In the past, patients confronted with this disease required life saving surgeries like short above knee or hip disarticulation amputations. This procedure always limited the lifestyle considerably for those patients. Rotation Plasty procedures and the design of appropriate prosthetics will allow those patients to function the same or better then Below Knee Amputees. To assist I wish to share my thoughts and experiences with others who may attempt fittings currently or in the future.

This paper will outline the patient interview, assessment, fabrication methods, fitting issues, component selection, thought on visual appeal and other considerations.

Patient Interview:

Patient sitting, displaying 180-degree rotated right leg

This probably should be worded "Patient Family Interview". In order to obtain a treatment plan, which will result in a successful outcome, not just the patient*should to be interviewed. The family plays a vital part in the overall successful patient fitting process. All aspects and concerns of family members need to be addressed, such as school environment, activities, family concerns, appearance and functional aspect, component selection, and much more. They need to be informed of the limitations of function and cosmetic appearance; otherwise the outcome will be compromised. Always take the time to sit down, even in successive fittings, and listen carefully to all the concerns. Sometimes they are not always instantly presented and it is an art to see beyond the spoken word. But by following these rules a sense of trust can be developed and the clinician is on the way to a successful. treatment plan.

The Multidisciplinary Team:

In most of instances, especially with new patients who have recently undergone rotation plasty surgery, a multidisciplinary team is involved with the patient. The members of that team have usually had the chance to interact with the patient pre and post surgery and acquire a vast knowledge of the patient and the family prior to the prosthetists involvement. The physiotherapist, social worker, occupational therapist and the surgeon can be of valuable assistance at all times. These patients, particularly the pediatric ones, are usually followed in a clinic setting and the input from the clinic is essential to a positive outcome.

Clinical Evaluation and Measurements:

Patient standing, right leg not touching the ground

Careful examination is fundamental. Range of motion measurements are essential for the subsequent alignment of the prosthesis. The clinical picture presents a lower limb with the foot rotated 180 degrees. Usually the tibia / fibula is attached to the femur at the level of the lesser trochanter, and the ankle joint acts as a knee joint. This allows keeping the main hip muscle system to stay intact. In some instances you may see the hip joint fused. Muscle strength and weight of the patient will determine the activity level and the subsequent component selection. Skin condition and scarring will direct prosthetic interface materials to be used and trimlines to be established. Range of motion in the Forefoot and the toes need to be checked. Measurements are taken longitudinal and circumferentional as needed. Taking a plaster negative mold is still the only way to acquire an exact positive reproduction of the residual limb.

I take my mold with the patient sitting with the edge of his buttock, ankle extended to the maximum. I apply a spandex type stumpsock to the patients leg to achieve some slight tissue compression / firmness. Plaster is applied over a strip of polyethylene. The plaster mold is cut open over the polyethylene strip with a knife and removed. The plaster mold is filled with Plaster of Paris, the mold subsequently removed and discarded. The result is a positive replication of the patient's leg with the foot ankle in a comfortable maximum extension.

Plaster Modifications:

Placement of the sulcus support is crucial

Plaster mold modifications are done as usual, smoothing the thigh section and build-ups at the ankle joints need to be made. The foot, which is the weight-bearing component, needs special consideration. The heel and part of the arch are the major weight bearing areas. I like to make a generous sulcus support as an additional support area. This results in weight distribution over as wide an area as possible, not unlike a ladies high heel shoe. The support under the sulcus will result in a much healthier foot over the lifetime of these patients. A distal build up over the toes needs to be made so the end of the toes will not touch the end of the prosthetic socket under while bearing weight. Light smoothing of the dorsal area of the foot completes the modification process.

Check Socket:

I always fabricate a clear check socket from the plaster mold. The check socket is in two pieces for fitting, the foot section with a dorsal opening, and the thigh section as an anterior shell. I prefer an anterior rigid shell for the reason that soft closures on the posterior aspect ease sitting much like in sports bracing. For the external knee joints, placed at the anatomical ankle joints I like to utilize lightweight joints made from Titanium. The joints also need adjustable extension and flexion stops. I use the ones made by Fillauer Orthopedics. They do not corrode, but are somewhat flexible and therefore require some modifications to the lamination lay-up later on. I like the limited motion stops, as they support the ankle at the end of the ROM.

Remember, we are using an anatomical ankle joint as a functional knee joint and we need to protect this joint for many reasons and many years to come.

I start my fitting with the foot piece. Trimming is required until the foot just slips into the socket. If a dorsal foot opening is desired, design this now. Check for weight bearing under the heel, arch and sulcus support. (The sulcus support is made of firm foam, taped in so it can easily be moved if needed). Check for range of motion and trim as needed. The thigh section needs to be trimmed to size. I like to stay as far proximal as possible to provide maximum support and not to have the trim lines over any of the surgical scars. Now it is time to roughly align the side joints and combine the two sections. Check for correct positioning of the joints and again assure that the maximum amount of ROM is maintained without compromising support and weight bearing.

Fabrication:

Fabrication: Alignment of joints

I like to use a semi-firm foam interface to provide comfort in the prosthesis. Foam interfaces provide friction, a positive characteristic as it aids in suspension. I always line at least the foot section. Under weight bearing extreme forces are apparent, particularly over the dorsum of the foot, which is usually quite sensitive. I line the dorsum with soft tissue substitute-type foam. A normal acrylic lamination is performed using nylglass and carbon reinforcement materials for strength. It is important to include an I-beam reinforcement to the anterior thigh section to provide good M-L stability within the system. It is advisable to consult the patient / family in respect to some patterns and / or transfer-fabrics to be incorporated into the laminations to provide an appealing and "cool looking" prosthesis. After the lamination is complete the assembly of the socket and components can begin.

Components:

Components are the choice of the pros-thetist, who considers the needs of the patient in the selection. The components need to be reliable, lightweight and serve the need. In some active patients impact reducing pylons are indicated, some may need adjustable heel features, and for recreational limbs I favor the Carbon Graphite Foot Shank Systems as they are water proof and reliable. Consider components with dynamic feature whenever possible as we are treating a highly active and motivated population. Funding issues unfortunately may limit the choice of components, and so the above-mentioned systems are not always the ones of choice.

Static and Dynamic Fitting:

Dynamic alignment

At this time it all comes together, patient, components and socket. Foot, Ankle, and Modular System are assembled. The Foot-Socket is glued to the lower modules, either at the end of the toes or in the area of the arch, depending on the ROM of the patient. The fittings are performed as with any prosthesis, checking for comfort, support alignment, ROM etc. At this time I tape the prosthesis to the patient with fiber tape and perform an assessment of the dynamics as the patient walks. The most challenging part is the Trendellenberg type of shift. This is due to weak hip abductors. Remember, there has been a major intervention and the patient has been at rest for quite some time due to surgery and chemotherapy. Initially those patients will present a lateral shifting to compensate, but we expect this to disappear as they become more mobile and with physiotherapy. By proper medial lateral shifting of the weight line in respect to the foot this however can be overcome for the most part. Again check for maximum support, proper weight distribution, comfort and maximum ROM. The patient will need to guide you; they know best. There is no compromise, as mistakes at this time will cost dearly after the prosthesis has been completed.

Leg prosthesis

Finishing:

The choice of finishings are, as in the case of conventional prostheses, either hard or soft. The components such as dynamic ankles, impact-reducing pylons will dictate soft finish. We at times are requested to provide prosthesis with rigid hollow external finishes. They are more labor intensive, but the patients like them for their recreational limbs. Recreational prostheses will be used at the beach and in the water, and need to be water proofed. In general I use Carbon Graphite Systems like Springlite Feet with a foam connection to the hollow hard shell. The posterior obturator is padded and a Velcro closure is usually desired over the dorsum of the foot. The posterior closure over the "thigh" has a tongue incorporated and two 1 1/2" Velcro straps suffice to hold the system firmly to the foot. Suspension is gained by the closure over the dorsum of the foot and the posterior area over the heel by the cupping of the foot section especially in extension where it is needed most.

Conclusions:

Boy walking with leg prosthesis

The ultimate goal is to provide a prosthetic device which serves all the needs of the patient. The prosthesis needs to be lightweight, functional, comfortable, rugged, easy to maintain and cosmetically appealing.

It has been my experience that the sulcus support has proven beneficial not only for weight bearing, but it provides better proprioception to the prosthesis as the toes can curl around it and have somewhat of a "grasping function". Further the foot does not seem to hammock in the stumpsock and much greater comfort is gained. In the past I have seen cramping of toes and joint pain in the MTP and IP joints from that hammock effect, which can be reduced with the sulcus bar.

The other important feature is the limited motion joint system. As we transfer an ankle joint to the level of a knee joint we need to understand the forces created on that ankle. Support needs to be provided in the ML plane, and motion limiters need to be applied at the end of each motion range, extension and flexion. This way the patient will feel secure and confident. Otherwise the patient will always have the fear of spraining the ankle. We know only too well how this can compromise confidence and mobility.

Lastly, the prosthesis needs to be appealing. We are fortunate to have other options available to finish prosthetic devices. The old Caucasian color, for example, would not be my personal choice. Modern designs can enhance the appeal of prosthesis for this exceptional age group of patients. It takes some additional effort to provide the above choices, but it is well worth it and the subsequent rewards are unrivaled. The client will feel special and the family members will be indebted for that special effort and thought going into the patient treatment process.

Please allow me to verify, that fittings of this kind are very individual. One needs to understand that the above text only can be used for guidance only, as individual patients have individual concerns and needs.

The Author:

Director, Prosthetics /Orthotics
Kelowna General Hospital
Kelowna, BC

Acting Director , GF Strong Rehab Center,
Vancouver, BC

Consultant to BC Children's Hospital
Vancouver, BC

Secretary, Canadian Board of Certification of P & O

Editor / Publisher, ACPOC NEWS

Authors Address:

Eugene Banziger, CPO
Director, Prosthetics Orthotics
Kelowna General Hospital
2268 Pandosy Street
Kelowna BC
Canada V1Y 1T2

E-mail: banziger@direct.ca