DIFFERENCES IN HIP MUSCLE STRENGTH AND STATIC BALANCE IN PATIENTS WITH TRANSFEMORAL AMPUTATIONS CLASSIFIED AT DIFFERENT K-LEVELS: A PRELIMINARY CROSS-SECTIONAL STUDY

BACKGROUND: Following amputation, patients with lower limb amputations (LLA) are classified into different functional mobility levels (K-levels) ranging from K0 (lowest) to K4 (highest). However, K-level classification is often based on subjective criteria. Objective measures that are able to differentiate between K-levels can help to enhance the objectivity of K-level classification. OBJECTIVE(S): The goal of this preliminary cross-sectional study was to investigate whether differences in hip muscle strength and balance parameters exist among patients with transfemoral amputations (TFA) assigned to different K-levels. METHODOLOGY: Twenty-two participants with unilateral TFA were recruited for this study, with four participants assigned to K1 or K2, six assigned to K3 and twelve assigned to K4. Maximum isometric hip strength of the residual limb was assessed in hip flexion, abduction, extension, and adduction using a custom-made diagnostic device. Static balance was investigated in the bipedal stance on a force plate in eyes open (EO) and eyes closed (EC) conditions. Kruskal-Wallis tests were used to evaluate differences between K-level groups. FINDINGS: Statistical analyses revealed no significant differences in the parameters between the three K-level groups (p>0.05). Descriptive analysis showed that all hip strength parameters differed among K-level groups showing an increase in maximum hip torque from K1/2-classified participants to those classified as K4. Group differences were also present in all balance parameters. Increased sway was observed in the K1/2 group compared to the K4 group, especially for the EC condition. CONCLUSION: Although not statistically significant, the magnitude of the differences indicates a distinction between K-level groups. These results suggest that residual limb strength and balance parameters may have the potential to be used as objective measures to assist K-level assignment for patients with TFA. This potential needs to be confirmed in future studies with a larger number of participants. Layman's Abstract Patients with lower limb amputation (LLA) are classified into different mobility levels, so-called K-levels, which are ranging from K0 (lowest) to K4 (highest). K-level classification is relevant for the patients as it determines the type of prosthetic components available. However, K-level can vary greatly based on the clinician or orthopedic technician individual assessment. Objective data from physical performance tests can help to improve K-level classification. Therefore, muscle strength tests of the amputation stump as well as balance tests were performed in this study to determine whether these parameters have the potential to support K-level classification. Twenty-two participants with a thigh amputation participated in the study (four K1/2-, six K3- and twelve K4-participants). Hip muscle strength on the amputation side was assessed as well as static balance in the double leg stance with eyes open and eyes closed. Analysis of the data showed that all hip strength parameters differed between the K-level groups, with maximum strength increasing from the K1/2 group to the K4 group. Group differences were also seen in the balance parameters with greater body sway for the K1/2 group when compared to the K4 group, especially when participants had their eyes closed. These results show that muscle strength tests of the residual limb and static balance tests may serve as additional measures to improve K-level assignment for patients with LLA. This was only an initial study and further studies with a larger number of participants are required to confirm these results. Article PDF Link: https://jps.library.utoronto.ca/index.php/cpoj/article/view/37456/28905 How To Cite: John S, Orlowski K, Mrkor K.U, Edelmann-Nusser J, Witte K. Differences in hip muscle strength and static balance in patients with transfemoral amputations classified at different K-levels: A preliminary cross-sectional study. Canadian Prosthetics & Orthotics Journal. 2022; Volume 5, Issue 1, No.5. https://doi.org/10.33137/cpoj.v5i1.37456 Corresponding Author: Stefanie John,Department of Sports Science, Faculty of Humanities, Otto von Guericke University, Magdeburg, Germany.E-Mail: [email protected] ID: https://orcid.org/0000-0001-6722-7195

Challenges and Potential in Targeted Muscle Reinnervation in Pediatric Amputees

Targeted muscle reinnervation (TMR) is a powerful new tool in preventing and treating residual limb and phantom limb pain. In the adult population, TMR is rapidly becoming standard of care; however, there is a paucity of literature regarding indications and outcomes of TMR in the pediatric population. We present 2 cases of pediatric patients who sustained amputations and the relevant challenges associated with TMR in their cases. One is a 7-year-old patient who developed severe phantom and residual limb pain after a posttraumatic above-knee amputation. He failed pharmacologic measures and underwent TMR. He obtained complete relief of his symptoms and is continuing to do well 1.5 years postoperatively. The other is a 2-year-old boy with bilateral wrist and below-knee amputations as sequelae of sepsis. TMR was not performed because the patient never demonstrated evidence of phantom limb pain or symptomatic neuroma formation. We use these 2 cases to explore the challenges particular to pediatric patients when considering treatment with TMR, including capacity to report pain, risks of anesthesia, and cortical plasticity. These issues will be critical in determining how TMR will be applied to pediatric patients.

Impact of post- amputation pain syndrome on the results of bone stump formation

Background. To the present day, a high rate of unsatisfactory amputation results still exists. The healing of the bone residual limb, the main support element of the residual limb, is of particular importance. Objective. To study the impact of postamputation pain syndrome on the nature of reparative processes in the bone residual limb. Methods. Three series of experiments were performed on 45 rabbits, 15 in each with mid-third thigh amputation and muscular plasty. In series 1 and 2, a perineural catheter was attached to the sciatic nerve stump during amputation, and mechanical irritation of the nerve was performed daily for 20 minutes in series 1 for 20 days. In series 2, 0.3 ml of 1% lidocaine was injected through the catheter into the circumference of the nerve twice daily for 20 days. Animals of series 3 served as a control. The follow-up periods were 1, 3, 6 months. The study method was histological with infusion of the vessels with ink-gelatin mixture. Results. In series 1, there was a sharp disturbance of the reparative process, which consisted in shape changes, resorption of the cortical diaphyseal plate, stump deformity, absence of bone closure plate formation, and microcirculatory disturbances. In most experiments of the 2nd series, organotypic stumps were formed with normalized microcirculation. In series 3, the results of the residual limb formation were better than in series 1, but worse than in series 2. Conclusion. In the absence of pain syndrome, the bone stump after amputation at the diaphysis level over a period of 1, 3, 6 months retains its cylindrical shape, the structure of the cortical diaphyseal plate, the content of the medullary canal with normal microcirculation, the formation of the bone closure plate, and the completion of the reparative process. The presence of postamputation pain syndrome in the stump distorts the course of the reparative process with the development of pathological remodeling of bone tissue.

Viscoelastic Polyurethane Foams for Use as Auxiliary Materials in Orthopedics

One of the essential factors in prostheses is their fitting. To assemble a prosthesis with the residual limb, so-called liners are used. Liners used currently are criticized by users for their lack of comfort, causing excessive sweating and skin irritation. The objective of the work was to develop viscoelastic polyurethane foams for use in limb prostheses. As part of the work, foams were produced with different isocyanate indexes (0.6–0.9) and water content (1, 2 and 3 php). The produced foams were characterized by scanning electron microscopy, computer microtomography, infrared spectroscopy, thermogravimetry and differential scanning calorimetry. Measurements also included apparent density, recovery time, rebound elasticity, permanent deformation, compressive stress value and sweat absorption. The results were discussed in the context of modifying the foam recipe. The performance properties of the foams, such as recovery time, hardness, resilience and sweat absorption, indicate that foams that will be suitable for prosthetic applications are foams with a water content of 2 php produced with an isocyanate index of 0.8 and 0.9.

Within-subjects Effects of Standardized Prosthetic Socket Modifications on Physical Function and Patient-Reported Outcomes

• Background: Among the challenges of living with lower limb loss is the increased risk of long-term health problems that can be either attributed directly to the amputation surgery and/or prosthetic rehabilitation or indirectly to a disability-induced sedentary lifestyle. These problems are exacerbated by poorly fit prosthetic sockets. There is a knowledge gap regarding how the socket design affects in-socket mechanics, and how in-socket mechanics affect patient-reported comfort and function. The objectives of this study are: 1) to gain a better understanding of how in-socket mechanics of the residual limb in transfemoral amputees are related to patient-reported comfort and function, 2) to identify clinical tests that can streamline the socket design process, and 3) to evaluate the efficacy and cost of a novel, quantitatively informed socket optimization process.• Methods: Users of transfemoral prostheses will be asked to walk on a treadmill wearing their current socket plus 8 different check sockets with designed changes in different structural measurements that are likely to induce changes in residual limb motion, skin strain, and pressure distribution within the socket. Dynamic biplane radiography and pressure sensors will be used to measure in-socket residual limb mechanics. Patient-reported outcomes will also be collected after wearing each socket. The effects of in-socket mechanics on both physical function and patient-reported outcomes (aim 1) will be assessed using a generalized linear model. Partial correlation analysis will be used to examine the association between research grade measurements and readily available clinical measurements (aim 2). In order to compare the new quantitative design method to the Standard of Care, patient reported outcomes and cost will be compared between the two methods, utilizing the Wilcoxon Mann-Whitney non-parametric test (aim 3).• Discussion: Knowledge on how prosthetic socket modifications affect residual bone and skin biomechanics itself can be applied to devise future socket designs, and the methodology can be used to investigate and improve such designs, past and present. Apart from saving time and costs, this may result in better prosthetic socket fit for a large patient population, thus increasing their mobility, participation, and overall health-related quality of life. • Trial registration: clinicaltrials.gov: NCT05041998