Total Surface Bearing Socket Research Articles

Insights into the spectrum of transtibial prosthetic socket design from expert clinicians and their digital records.

Transtibial prosthetic sockets are often grouped into patella tendon bearing (PTB) or total surface bearing (TSB) designs, but many variations in rectifications are used to apply these principles to an individual's personalised socket. Prosthetists currently have little objective evidence to assist them as they make design choices. To compare rectifications made by experienced prosthetists across a range of patient demographics and limb shapes to improve understanding of socket design strategies. 163 residual limb surface scans and corresponding CAD/CAM sockets were analysed for 134 randomly selected individuals in a UK prosthetics service. This included 142 PTB and 21 TSB designs. The limb and socket scans were compared to determine the location and size of rectifications. Rectifications were compiled for PTB and TSB designs, and associations between different rectification sizes were assessed using a variety of methods including linear regression, kernel density estimation (KDE) and a Naïve Bayes (NB) classification. Differences in design features were apparent between PTB and TSB sockets, notably for paratibial carves, gross volume reduction and distal end elongation. However, socket designs varied across a spectrum, with most showing a hybrid of the PTB and TSB principles. Pairwise correlations were observed between the size of some rectifications (e.g., paratibial carves; fibular head build and gross volume reduction). Conversely, the patellar tendon carve depth was not associated significantly with any other rectification, indicating its relative design insensitivity. The Naïve Bayes classifier produced design patterns consistent with expert clinician practice. For example, subtle local rectifications were associated with a large volume reduction (i.e., a TSB-like design), whereas more substantial local rectifications (i.e., a PTB-like design) were associated with a low volume reduction. This study demonstrates how we might learn from design records to support education and enhance evidence-based socket design. The method could be used to predict design features for newly presenting patients, based on categorisations of their limb shape and other demographics, implemented alongside expert clinical judgement as smart CAD/CAM design templates.

Transtibial Prosthetic Socket Design and Suspension Mechanism: A Literature Review

ABSTRACT Introduction The body weight of the prosthetic user is supported and distributed by the prosthetic socket during the stance phase of gait. Throughout swing phase, inertial forces (pressure and shear) are exerted by the socket suspension mechanism onto the residuum to facilitate suspension. Objectives in the study were to identify and investigate available evidence in transtibial (TT) socket design and suspension to highlight the most effective weight transfer mechanisms and suspension techniques. Methods A literature research was conducted comprising two parts: socket design and suspension. Boolean search terms and truncation were used using relevant keywords in online search engines to obtain precise results. Results Seventeen articles that met inclusion criteria were reviewed. Conclusions A conclusion on whether socket preference is due to the suspension mechanism or socket design itself cannot be drawn. Patellar tendon bearing (PTB) sockets are still successfully used and, in some studies, preferred over total surface bearing (TSB) sockets. Biomechanically, however, TSB sockets allow for a more even weight distribution when combined with suction, particularly vacuum-assisted socket suspension (VASS). Some limited evidence exists to support that such designs may have some effect on wound healing and early ambulation. Further research must be conducted to standardize acclimation periods. Crossover randomized controlled trials with larger sample sizes are required to establish an evidence base to improve clinical practice.

A comparison between the suction suspension system and the hypobaric Iceross Seal-In® X5 in transtibial amputees

The two passive vacuum suspension systems currently available in total surface-bearing sockets are the hypobaric Iceross Seal-In(®) and the suction suspension system. The purpose of this study was to compare the effect of the hypobaric Iceross Seal-In(®) liner with that of the suction suspension system for quality of life, pistoning, and prosthesis efficiency in unilateral transtibial amputees. Single-group repeated measures. Ten amputees were enrolled. The pistoning test, used to compare vertical movement of the stump within the socket, and the energy cost of walking test were carried out when the amputees were wearing the suction suspension system and after 2, 5, and 7 weeks of Seal-In® X5 use. The Prosthesis Evaluation Questionnaire and the Houghton Scale Questionnaire of perceived mobility and quality of life with the prosthesis, and the Timed Up&Go Test and the Locomotor Capability Index for functional mobility were also administered at the beginning and end of the study. The hypobaric Iceross Seal-In® X5 led to significant pistoning reduction and improvement on the Houghton Scale Questionnaire and 3 of 9 domains of the Prosthesis Evaluation Questionnaire. No statistical changes were observed in functional mobility or the energy cost of walking tests. Replacing the suction suspension system with the hypobaric Iceross Seal-In® X5 improves quality of life in transtibial amputees.

The effectiveness of total surface bearing compared to specific surface bearing prosthetic socket design on health outcomes of adults with a trans-tibial amputation: A systematic review.

Review objective The objective of this systematic review is to synthesise the best available evidence informing the effects of prosthetic socket design on outcomes of function, mobility, comfort and pain, energy expenditure, prosthetic and health related quality of life of adults with a trans-tibial amputation. Specifically, the review will consider studies evaluating the effects comparing the contemporary total surface bearing (TSB) socket design with the more traditional specific surface bearing (SSB) socket design Inclusion criteria Types of participants This review will consider adult trans-tibial amputees 18 years or older, with acquired or congenital limb loss irrespective of the aetiology, gender or the presence of co-morbidities using prostheses with either the contemporary total surface bearing (TSB) socket design or the traditional specific surface bearing (SSB) socket design. Each of the studies considered for inclusion will have documented study populations utilising both TSB and SSB socket designs within the study. Types of interventions The intervention of interest is the use of TSB socket. This is the ‘hydro static’ design or ‘limited load bearing’ often using silicon or gel liner interface, with suspension achieved via distal attachment of pin and lock or lanyard, expulsion valve and sleeve, vacuum assisted, integrated membrane seal or a combination of these. The comparative intervention will be the use of a SSB socket. This is often referred to as PTB, PTS, PTB-SC, PTK or KBM, typically utilising soft foam liner interface paired with supracondylar suspension. Types of outcomes This review will consider studies that include but will not be limited to the following outcomes: • Function and Mobility measured for example using Amputee Activity Score (AAS) or Locomotor Capabilities Index (LCI-5) or Timed Walk Tests (TWTs) or Step Activity Monitor (SAM); • Comfort and Pain measured for example using Socket Comfort Score (SCS) or Brief Pain Inventory (BPI); • Quality of Life including: Prosthetic Related Quality of Life (PRQoL) measured for example using Prosthetic Evaluation Questionnaire (PEQ) and Health Related Quality of Life (HRQoL) measured for example using Trinity Amputation & Prosthesis Experience Scales (TAPES) or Short Form 36 (SF-36); • Energy Expenditure measured for example using Physiological Cost Index (PCI).

Poster 303: Total Surface Bearing Socket for a Below-Knee Prosthesis: Preference, Satisfaction, and Clinical Implications

Objective: To evaluate the preference of transtibial amputees for the total surface bearing (TSB) socket versus the patellar tendon bearing (PTB) socket, to examine the reasons for their preferences, and to determine the clinical indications of each socket prosthesis. Design: Cross-sectional study. Setting: Community. Participants: 71 subjects who could walk with the total surface bearing prosthesis and had already used the patellar-tendon bearing prosthesis. Interventions: Not applicable. Main Outcome Measures: The subjects responded to a questionnaire, including information, functional ability, satisfaction, and preferences for the TSB socket compared with the PTB socket.

Case Report: Variably Compliant Transtibial Prosthetic Socket Fabricated Using Solid Freeform Fabrication

Achieving and maintaining a comfortable fit in a lower-limb prosthetic socket is an important goal to help ensure a successful rehabilitation. The purpose of this case study was to assess the performance of sockets with compliant features integrated into the socket wall to relieve in-socket pressure during transtibial amputee gait. Two sockets incorporating variably compliant areas over the fibula head and distal tibia were fabricated for a transtibial amputee. The two sockets were designed with different levels of compliance and were compared with a third more conventional socket without compliant areas. All three sockets were otherwise geometrically identical and were aligned identically to eliminate in-socket pressure differences due to alignment. The three sockets were fabricated using selective laser sintering, a form of solid freeform fabrication. The in-socket pressure measurements were acquired during normal walking. Tekscan F-Socket pressure sensors were attached to the amputee’s residual limb rather than to the socket wall, which made it possible to measure pressures in the same location on the residual limb upon change of socket. A Vicon motion capture system was used to match in-socket pressures to the subject’s gait cycle. The pressure measurements showed that the compliant socket peak pressures over the distal tibia and fibula head were similar for the two compliance levels and nearly 50% and 30% lower than the conventional socket pressures, respectively. This case study showed that selective laser sintering manufactured sockets with variably compliant regions holds great promise for reducing contact pressure in sensitive regions of the residual limb. (J Prosthet Orthot. 2008;20:1‐7.) KEY INDEXING TERMS: prosthetic socket, amputees, CAD, CAM, solid freeform fabrication T he most important aspect of a lower extremity transtibial prosthesis is the socket design. The socket introduces a new interface or a new joint between the human and the mechanical support system. The forces generated through the socket either by body weight or by gait have to be carried by the soft tissue of the residual limb, which when improperly loaded can lead to discomfort or skin breakdown. Ultimately, the design and fit of the socket is what determines patient acceptance, comfort, suspension, and energy expenditure. 1 Achieving and maintaining a comfortable and tissue-tolerant socket fit remains a significant clinical problem. This study explores the use of new manufacturing techniques to fabricate sockets with integrated compliant features specifically designed to improve comfort and fit of the prosthesis.

A randomized controlled trial comparing functional outcome and cost efficiency of a total surface-bearing socket versus a conventional patellar tendon-bearing socket in transtibial amputees

Selles RW, Janssens PJ, Jongenengel CD, Bussmann JB. A randomized controlled trial comparing functional outcome and cost efficiency of a total surface-bearing socket versus a conventional patellar tendon-bearing socket in transtibial amputees. Objective To compare functional outcome and cost efficiency of a total surface-bearing (TSB) socket with a conventional patellar tendon-bearing (PTB) socket in transtibial amputees. Design Prospective randomized controlled trial. Setting Outpatient rehabilitation clinic of a general hospital, rehabilitation research department of a university hospital, and certified prosthetics and orthotics workplace. Participants Twenty-six adult unilateral transtibial amputees walking with a prosthesis for at least 1 year. Intervention Subjects were randomly assigned to 2 groups: one receiving an ICEX TSB socket, the other a conventional PTB socket. Main outcome measures Prosthetic Evaluation Questionnaire (PEQ) score, mobility-related activities of daily life, and gait characteristics at baseline and 3 months after initial socket fitting, as well as cost of materials, manufacturing time, and number of visits and interventions. Results No significant differences were found between both groups in terms of changes in socket function (PEQ scores, mobility-related activities, gait characteristics). In the TSB sockets, cost of materials was significantly larger, but the manufacturing time was significantly shorter and the number of visits was significantly less than in the PTB sockets. Conclusions Both sockets performed equally well in terms of patient satisfaction, mobility-related activities performed during daily life, and gait performance. Material costs were higher in the TSB group, whereas the manufacturing time in the TSB group was lower.

Hygiene problems of residual limb and silicone liners in transtibial amputees wearing the total surface bearing socket

Hachisuka K, Nakamura T, Ohmine S, Shitama H, Shinkoda K. Hygeine problems of residual limb and silicone liners in transtibial amputees wearing the total surface bearing socket. Arch Phys Med Rehabil 2001;82:1286-90. Objective: To determine whether washing the residual limb and silicone liner reduces the associated skin problems in transtibial amputees who wear a total surface bearing (TSB) socket. Design: Case series. Setting: General community. Patients: Eighty-three transtibial amputees (65 men, 18 women; mean age, 53.4yr) in western Japan who used or had used a TSB socket with a silicone liner in the previous 5 years. Intervention: Participants took a self-administered questionnaire that included items concerning their personal profile, daily life activities, period of TSB use (yr), hours of TSB use daily, washing frequency of the residual limb and silicone liner, the method of washing, and any associated hygiene problems. Main Outcome Measures: Logistic regression analysis was applied to examine factors related to hygiene problems. Predicted values include hygiene problems (perspiration, eruptions, itching, odor) and explanatory values include TSB use, daily life activity, and washing of limb and prosthetic. Results: Fifty-five subjects washed the residual limb, and 44 subjects washed the silicone liner every day. Itching, perspiration, eruption, and odor were frequent hygiene problems. Perspiration was noted less by women, eruption more by older subjects, and itching and odor more by younger subjects. Washing the silicone liner every day was associated with fewer reports of skin eruption. Conclusion: Keeping the residual limb and silicone liner clean is important to reduce skin problems, but hygiene problems of the residual limb and silicone liner still remain to be resolved. © 2001 by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation

Properties of the flexible pressure sensor under laboratory conditions simulating the internal environment of the total surface bearing socket.

The purpose of this study was to investigate the properties of the flexible pressure sensor under laboratory conditions simulating the internal environment of the total surface bearing (TSB) socket to determine optimal conditions for measuring normal stresses on the stump. The equipment used in the study was the Pressure Distribution Sensor System for Sockets. In a climatic chamber maintained at 37 degrees C and 70% humidity the sensor sheet was mounted on a measuring apparatus loaded with three 10 kg weights, and output from the sensor was recorded. Because of sensor creep, a sample 60 seconds after loading was adopted as the measured output. Output was greater when weight was decreased than when weight was increased because of hysteresis (paired t-test, p<0.05). The sensor had temperature sensitivity but differences in output were not statistically significant (paired t-test, 0.10>p>0.05). There were no significant differences in output among five sensor sheets or among five sections of four sensor sheets (two-way ANOVA, p>0.05), but repeated loading on the same section of the sensor sheet increased output (two-way ANOVA, p<0.05). Reproducibility and sensitivity distribution of the sensor are considered satisfactory under laboratory conditions, but measurements of rapid and repetitive movements may not be accurate and comparing subtle changes in output from a single sensor is not suitable. The reliability of the sensor in a clinical setting for measuring normal stresses on the stump with the TSB socket should be examined.

Total surface bearing below-knee prosthesis: Advantages, disadvantages, and clinical implications

Objective: To investigate the total surface bearing (TSB) prosthesis for below-knee amputee patients and to determine its clinical indications. Design: Case series. Setting: University hospital and the Welfare Center for the Disabled. Patients: Thirty-two subjects who could walk with the TSB prosthesis and had already used the patellar-tendon bearing (or Kondylen-Bettung Münster) socket. Main Outcome Measure: Subjective assessment of the TSB socket, consisting of an overall rating and ratings of 13 individual items, was performed, and results were analyzed with Fisher's exact test. Results: Seventy-five percent of the subjects were satisfied overall with the TSB socket. Of the 13 items, comfort, ease to swing, pain, piston movement, tightness, skin irritation, appearance, and durability were regarded as good by more than 75% of the patients. Donning, perspiration, odor, and staining were regarded as poor by more than 20%. Items that were significantly related with overall satisfaction with the TSB socket were comfort, ease to swing, and piston movement, while donning was significantly related to dissatisfaction. Conclusion: The TSB socket is suitable for and preferred by many amputee subjects, but some problems remain to be solved.