How to Fabricate a Custom Transtibial Rigid Removable Dressing

The benefits of fitting a rigid removable dressing (RRD) soon after transtibial amputation surgery have been well documented. RRDs enhance healing by immobilizing and supporting soft tissues. They prevent post-operative edema, protect the residuum from possible falls or trauma, and enable frequent access to the limb wound site. 1 RRDs also help acclimate the limb to a total-contact environment, reduce phantom sensations and pain, and are effective in volume control. RRDs can be worn full time while the preparatory prosthesis is being fabricated and should be used during pre-prosthetic training and therapy. They are also a useful tool that can be worn intermittently with the prosthesis until the patient has built up tolerance to a full-time wear schedule. This project began about ten years ago in an effort to fabricate a low-profile, lightweight, custom transtibial RRD on-site using simple tools and materials. The model is essentially a modern version of the RRD designed and developed by Yeong-Chi Wu, MD, and Harold Krick, CP, at the Rehabilitation Institute of Chicago in 1977. 2 Some of the materials are different, but overall, the concept and design were inspired by their work. Evidence-based medicine from a retroactive study of the last 40 years of documented clinical work, published in 2018, reveals that post-operative care is one of the four factors that influence successful outcomes for people with transtibial amputations. The two elements of post-operative care that can significantly contribute to prosthetic success are facilitating and arranging an appropriate peer encounter for the patient and the early fitting of an RRD. 2 History Rigid dressings have been used for more than 100 years. There is mention of a Hungarian surgeon fitting post-amputation patients during World War I with a rigid dressing (plaster) and attaching wooden or metal pylons to help with early mobilization for those patients. 3 During the 1970s and 1980s in the United States, nonremovable, thigh-high rigid dressings were used, but they lost favor with physicians because the dressings, which usually need to be cut with a cast saw, did not allow for easy wound inspection. Since that time, a number of custom and prefabricated RRDs have been developed that can be easily donned and doffed for wound inspection and offer access to the surgical site. Compression Therapy Sometimes fitting an RRD can be conjoined with compression therapy depending on the physician’s request. Typically sutures or staples are in place and the residuum is swollen and very sensitive (Figure 1). Prosthetists sometimes fit a loose and stretchy nylon sheath over the residuum first. This helps cover the protruding sutures or staples and prevents the shrinker or socks from catching and pulling them while donning, whether a one-layer Juzo-style or doubled-over Compressogrip-type sleeve is used. Sometimes a donning device such as a section of short, wide circumference (6-, 8-, or 10-inch) PVC pipe can be used to pre-stretch the shrinker and reflect it onto the residuum. This avoids pulling fabric across the sensitive residuum but may be difficult for the patient to manage independently. An alternate method is to apply a long elastic wrap over the sheath using a figure-of-eight pattern, which is less likely to disturb the sutures. Preparing the Residuum Proceed, with or without compression therapy, by applying a loose, stretchy, five-ply sock (and three-ply if no compression garments are used), and then roll on a three-ply post-operative sock. (Note: If there is excessive distal swelling, then acrylic padding will need to be blended in proximally to facilitate donning and doffing.) Use generous sizing for the post-operative sock to prevent bridging inside the RRD since it will become the inner lining of the RRD (Figure 2). Next cut a strip of soft ⅜-inch thick acrylic padding to cover bony prominences like the full length of the tibial crest, including the patella, tibial tubercle, and beveled distal end (which looks kind of like a dog bone), and also a piece to fit over the fibular head (Figure 3). Extend the fibular head and patella pads proximally above the trimline so you can later reflect them back over the rigid dressing to further soften the edges over those sensitive areas. Use 1-inch double-sided tape and add this to the pads and stick them in place on top of the sock. (See video.) Fitting a Distal End Pad Next, select a reticulated distal end pad that fits snugly without any loose spots or creases. Usually 4- or 5-inch works well, as it typically covers the padding over the beveled tibia distally. You want a uniform transition from the distal end pad into the post-operative sock. Once this is fitted distally, mark the top edge by using discreet dots with permanent marker on the sock. Remove the distal end pad and apply sticky-back tape to the post-operative sock where the end pad is located. To prevent creasing and folds, you may find it easier to invert and roll on the distal end pad once the tape is in place. Finally, use permanent marker to make discreet dots on the sock for the proximal trim line beginning with mid-patella and making a sloping line to just underneath the knee crease posteriorly to allow for knee flexion. (See video available at opedge.com.) Synthetic Casting Tape Wrap Now you are ready to begin the wrap. Three- or 4-inch rolls of synthetic casting tape can be used. This is a loose wrap with no roping. Start by wrapping two layers evenly about 1.5 inches above the marked trimline and then wrap the excess diagonally across the residuum in similar fashion to an elastic bandage. (Note: You will not cover the entire residuum with this first roll unless the residuum is very short or small). Use just one roll, and once the end is reached go back to the proximal edge and gently and uniformly roll down the edge before it sets up around the entire limb to create a round edge; continue until you see the dots marking the trimline. This technique creates the beginning of a soft, rounded edge for a material that is otherwise inherently abrasive. Finish with one or two more wraps to cover the limb with approximately two layers of material and let set. Once the material has hardened, grasp and reflect the post-operative sock over the cast, remove it, and gently place it near the sink upside down. Cut short pieces of casting tape and apply across the distal end of the dressing as needed for enough strength to resist the impact of a fall. Now reflect the sock onto the cast and cut it about 1.5-2 inches below the trimline. Use another roll of casting tape and bring the wrap edge up just under the round edge and work down across the sock into the cast. This retains the sock over the edge and reinforces the strength of the cast. Try to capture the ends of the short reinforcing pieces with the wrap and blend into the rigid cast. Let the RRD set (Figure 4). Adjusting the Fit, Donning and Doffing, and Sock Management Depending on the length and shape of the residuum, you will probably need to remove the five-ply sock used during casting and don the RRD over a three-ply sock or sometimes even over a one- or two-ply. Gentle contact, not pressure, is the goal, especially if shrinkers have been used. Select the appropriate size fabric suspension sleeve and demonstrate and assist the patient with donning and doffing techniques (Figure 5). This is a good time to explain sock management to the patient and schedule a follow-up in a week to ensure he or she is using the RRD in the correct fashion. Observations If desired, the pads covering the bony prominences could be put in place underneath the three-ply post-operative sock and removed after casting to leave voids. This technique was used in the Wu and Krick model. 2 Advantages This custom RRD is a proven model and has worked well with good clinical benefits. The model is cleaner and faster to fabricate than plaster ones and much lighter. It is less bulky than most prefabricated RRDs and easy to manage. Patients tend to be more compliant with a device that is lightweight and simple to don and doff. It can be fabricated on-site in less than an hour using the tools and equipment described. Although not clinically documented yet, it is probable that a custom RRD is more effective in healing properties than prefabricated models because it more intimately captures unique contours to immobilize and support the soft tissues. Disadvantages Synthetic casting tape, distal end pads, prosthetic socks, and fabric suspension sleeves are more expensive than plaster, cotton padding, and tube socks that are used for the Wu and Krick model, for example. This low-profile model allows for knee flexion and will not prevent knee flexion contractures. Custom RRDs, whatever the model, probably take more time and skill to fit and may be more expensive than prefabricated models. Conclusion Today’s healthcare settings and practices pose timely challenges in post-operative management and early prosthetic intervention for people following amputation. It is imperative to try and intercept those patients before they are discharged from the hospital, which is usually between three and five days post-operatively, and fit them with a custom or prefab RRD and arrange to coordinate an appropriate peer encounter. Bret Laurent, CP, is a retired prosthetist interested in post-operative management of patients following new amputations, especially for at-risk populations in the United States. References Reichmann, J.P., and A. E. Krittter. 2018. Evidence-based post-operative care for transtibial amputees. The O&P EDGE 17(6):30-4. Wu, Y., R. D. Keagy, H. J. Krick, J. S. Stratigos, and H. B. Betts. 1979. An innovative removable rigid dressing technique for below-the-knee amputation. Journal of Bone and Joint Surgery American Volume 61:724-9. Wilson, P. D. 1922. Early weight-bearing in the treatment of amputations of the lower limbs. Journal of Bone and Joint Surgery American Volume 4(2):224-7 . Additional Notes In Figure 3 looking inside the RRD, the padding for the fibular head (to the left) and tibial crest and beveled distal tibia (lower aspect also showing the black, reticulated distal end pad) can be seen. At this time cotton stockinette was used as a liner. The three-ply post-operative socks were used later. In the video, the black, cubed sticky-backed foam was used to pad bony areas. Later, soft 3/8-inch thick acrylic padding used in lamination was used. Also, the RRD fabricated in the video was a cast replacement made some weeks after surgery, so the patient’s residuum was not as swollen or sensitive as most are several days after surgery. The first RRD was made in the hospital and can be seen on the floor. Thanks to Pacific Medical Inc. for permission to use their video. Thanks to Elzer Ramos for camera work, lighting, editing, and time-lapse footage. Thanks to Ralph Nobbe, CPO, for supporting and encouraging early efforts to develop the model. Thanks to Marty and Kary Herman for allowing us to use their rehabilitation for educational purposes. Additional Reading Schon, L. C., K. W. Short, and O. Soupiou, et al. 2002. Benefits of early prosthetic management of transtibial amputees: a prospective clinical study of prefabricated prosthesis. Foot Ankle International 23:509-14. Burgess, E. M. 1971. Immediate postsurgical prosthetic fitting: A system of amputee management. American Journal of Physical Therapy 51:139-143. Jaime, C. Y., K. Lam, and A. Nettel-Aguirre, et al. 2010. Incidence and risk factors of falling in the postoperative lower limb amputee while on the surgical ward. PM&R 2(10):926-34. Sumpio, B., S. R. Shine, D. Mahler, and B. E. Sumpio. 2013. A comparison of immediate postoperative rigid and soft dressings for below-knee amputations. Annals of Vascular Surgery 27(6):774-80. Taylor, L., S. Cavenett, J. M. Stepien, and M. Crotty. 2008. Removable rigid dressings: A retrospective case-note audit to determine the validity of post-amputation application. Prosthetics and Orthotics International 32(2):223-30. Smith, D. G., L. V. McFarland, and B. J. Sangeorzan, et al. 2003. Postoperative dressing and management strategies for transtibial amputations: A critical review. Journal of Rehabilitation Research and Development 40(3):213-24.

How to Fabricate a Custom Transtibial Rigid Removable Dressing

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