Aims

Prior cost-effectiveness analyses on osseointegrated prosthesis for transfemoral unilateral amputees have analyzed outcomes in non-USA countries using generic quality of life instruments, which may not be appropriate when evaluating disease-specific quality of life. These prior analyses have also focused only on patients who had failed a socket-based prosthesis. The aim of the current study is to use a disease-specific quality of life instrument, which can more accurately reflect a patient’s quality of life with this condition in order to evaluate cost-effectiveness, examining both treatment-naïve and socket refractory patients.

Aims

Safety concerns surrounding osseointegration are a significant barrier to replacing socket prosthesis as the standard of care following limb amputation. While implanted osseointegrated prostheses traditionally occur in two stages, a one-stage approach has emerged. Currently, there is no existing comparison of the outcomes of these different approaches. To address safety concerns, this study sought to determine whether a one-stage osseointegration procedure is associated with fewer adverse events than the two-staged approach.

Abstract. Objectives. Osteoporosis of the pelvis and femur is diagnosed in a high proportion of lower-limb amputees which carries an increased fracture risk and subsequently serious implications on mobility, physical dependency and morbidity. Through the development of biofidelic musculoskeletal and finite element (FE) models, we aim to determine the effect of lower-limb amputation on long-term bone remodelling in the hip and to understand the potential underpinning mechanisms for bone degradation in the younger amputee population. Methods. Our models are patient specific and anatomically accurate. Geometries are derived from MRI-scans of one bilateral, above-knee, amputee and one body-matched control subject. Musculoskeletal modelling enables comparison of muscle and joint reaction-forces throughout gait. This provides the loading scenario implemented in FE. FE modelling demonstrates the effect of loading on the amputated limb via a prosthetic socket by comparing bone mechanical stimulation in amputee and control cases. Results. Musculoskeletal modelling shows that the bilateral amputee has 25% higher peak hip-reaction force than controls but a 54% lower peak knee-reaction force. Compensation for missing muscles and joints cause large-scale changes to the muscle loading patterns of the residual limb. FE analysis shows a 32% reduction in bone stimulation within the proximal femur and an 81% reduction in the distal femoral shaft when compared to the healthy control. A shielding effect from weight-bearing through a prosthetic socket was observed that may offset any increases in joint and muscle loading at the amputated hip. Conclusions. Bone loss in the young amputee population could be driven by unloading osteopenia where altered joint and muscle loads cause altered mechanical stimulus in the femur. Over many cycles of remodelling, a net bone loss occurs. Importantly, this suggests that the issue is preventable, or even reversible, with the implementation of targeted loading regimes or changes to the design of the prosthetic socket. Declaration of Interest. (b) declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported:I declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project

Introduction. This study reports on minimum 2 year follow up outcomes on functional and quality of life of patients after undergoing bilateral osseointegration in comparison to traditional socket prosthesis. Materials & Methods. This is a prospective pilot study of 35 patients, consisting of 30 males and 5 females, aged 22–66 (mean 36) years at surgery, with minimum two-year follow-up. Selection criteria were age over 18 years, bilateral amputees who had socket-related problems or were wheelchair-bound with short stumps and non-reconstructable limb pathology. Principle outcome measures included the Questionnaire for persons with a Trans-Femoral Amputation (Q-TFA), Short Form Health Survey 36 (SF-36), Six Minute Walk Test (6MWT), Timed Up and Go (TUG), and K-levels. Adverse events were recorded including infection, revision surgery, fractures, and implant failures. Results. Comparisons were made using differences between the mean pre-operative and mean post-operative values for each outcome measure. Significant improvements in all validated outcome measures were observed. All patient who were wheelchair bound prior to the surgery were able to mobilise post operatively. The occurrence levels of adverse events, including the infection rate and revision rate within this patient cohort, were similar to other established trans-femoral osseointegration studies. Conclusions. These preliminary results indicate that osseointegration surgery is a safe and effective alternative treatment for bilateral amputees experiencing socket-related discomfort. Compared to the suboptimal outcomes of socket prostheses, osseointegration currently provides one of the best chances for any bilateral amputee to walk again and regain the ability to perform daily activities

Introduction. Approximately 2,000 Skeletal transcutaneous osseointegration (STOI) procedures have been performed worldwide as of 2020, more than half of which have been performed by the Osseointegration Group of Australia using a press-fit technique with either ILP or OPL implant designs. Despite the consistently demonstrated clinical benefits, concerns regarding potential complications following STOI have slowed its widespread adoption. As more patients are followed for a longer period of time, longitudinal studies have confirmed complication rates are very acceptable, similar to those of total ankle and total elbow replacements. One of the major risk category is implant removal. The primary goal of this study was to investigate the complications and technical issues associated with transtibial osseointegration implant removal due to any cause. The focus here will be on the press-fit ILP and OPL implants, including the indications for removal and patient outcomes following removal. Materials & Methods. A review of our osseointegration registry between November 2010 and March 2022 was performed. Inclusion criteria were patients who have undergone removal of a transtibial osseointegration implant due to any cause. Selected patients either had a follow-up of at least two years or had their index osseointegration surgery at least two years prior to when the study was performed. Patients who have had osseointegration at other anatomic levels, and patients who underwent simultaneous total knee replacement with transtibial osseointegration were excluded from the registry search. Results. There were a total of 148 transtibial osseointegration procedures performed during the study period, with 97 (65.5%) performed in males and 51 (34.5%) performed in females. The average age at first stage osseointegration procedure is 50.4 years (range 16.8–87.9, SD 14.1). In the study cohort of 22 cases requiring implant removals, 12 (54.5%) were male and 10 (45.5%) were female. The average age at first stage osseointegration procedure in this cohort is 51.3 (range 37.4–82.6, SD 10.7) and average BMI 30.3 (range 21.9–40.9, SD 5.8). Although men comprised the majority of removals, women had a greater relative risk (Fisher exact test p=0.032). The average duration from time of STOI to removal was 2.6 years (range 0.1–6.8, SD 1.9) within this 11.5 year follow-up period. The most frequent indication was infection (54.6%, n=12) followed equally by pain (13.6%, n=3), aseptic loosening (13.6%, n=3) and implant fracture (13.6%, n=3), and lastly failure to integrate (4.6%, n=1). Conclusions. Of the 22 removals, 12 were reimplanted at the same anatomical level (10 were reimplanted within 6 months, 1 within 12 months, and 1 within 24 months). 11 of these cases currently wear their prosthetic legs for more than 13 hours daily. 1 case was recently reimplanted and still completing their loading program. Of the patients who were not reimplanted at the same anatomical level, 1 required proximal amputation with transfemoral osseointegration. 3 patients converted to traditional socket prostheses (TSP) due to pain, and 1 underwent proximal amputation and converted to TSP due to infection. 3 cases are currently awaiting transtibial osseointegration reimplantation, and 1 patient was deceased. 1 patient was lost to follow-up

Purpose: The purpose of this work was to determine the feasibility of using the Surfix anchored hip socket for revision arthroplasty after dysplasia or dislocation. Material and methods: The series included 45 total hip arthroplasties revised between 1991 and 1995 in 42 patients. Four patients (five hips) had died before five years (at 2, 3, 3, 4 and 4 years) and two others were lost to follow-up (at 1 and 1 year). Thirty-six patients (38 hips) were retained for analysis. There were eight men and 28 women, mean age 60 years (24–74). Mean follow-up was 6.5 years (5–9). There were 20 high or intermediary malformations, 13 severe dysplasias, and five minor dysplasias; 34% had been operated on earlier. The acetabulum was gouged out to the paleoac-etabulum in all cases except one. Primary stability of the acetabulum was achieved with a Surfix anchor. With this anchorage system, the screw that crosses the acetabulum and is screwed into the bone is fixed to the prosthetic socket via a counter-sink placed in the head of the transverse screw. A femur head was used to reconstruct the acetabulum: the entire head was used in two cases, small cubes cut out of the head in 24, and ground head material in 12. The reconstruction bone was driven into the defect between the iliac wing and the implant after its fixation to solidarise the anchorage screws. Results: There were two cases of regressive sciatic palsy. One case of progressive migration was observed after reconstruction in a patient with a high dislocation who underwent revision at two years for a new Surfix acetabulum. The final result was good but this case was withdrawn from the analysis. Clinical outcome for the 37 remaining patients were: pain 5.9 (35X6 – 2X5), motion 5.8 (33X6 – 3X5 – 1X4), walking 5.6 (26X6 – 10X5 – 1X4). Radiographically, the reconstruction of the bony acetabulum was good with rehabilitation and neocorticalisationof the graft material. There were modifications of the bony condensations and corticalisation around the screws. There were no displacements of the prosthetic socket and no cases with lucent lines. Discussion: Independent acetabular screws cannot participate in resistance against compression. They become functional and effective when they are solidarised to the socket. They can be anchored in the bony columns allowing very good primary fixation. Conclusion: The clinical and radiological results confirm the usefulness of the Surfix socket anchor when there is no bony support for the prosthetic socket

Aims. The Intraosseous Transcutaneous Amputation Prosthesis (ITAP) may improve quality of life for amputees by avoiding soft-tissue complications associated with socket prostheses and by improving sensory feedback and function. It relies on the formation of a seal between the soft tissues and the implant and currently has a flange with drilled holes to promote dermal attachment. Despite this, infection remains a significant risk. This study explored alternative strategies to enhance soft-tissue integration. Materials and Methods. The effect of ITAP pins with a fully porous titanium alloy flange with interconnected pores on soft-tissue integration was investigated. The flanges were coated with fibronectin-functionalised hydroxyapatite and silver coatings, which have been shown to have an antibacterial effect, while also promoting viable fibroblast growth in vitro. The ITAP pins were implanted along the length of ovine tibias, and histological assessment was undertaken four weeks post-operatively. Results. The porous titanium alloy flange reduced epithelial downgrowth and increased soft-tissue integration compared with the current drilled flange. The addition of coatings did not enhance these effects. Conclusion. These results indicate that a fully porous titanium alloy flange has the potential to increase the soft-tissue seal around ITAP and reduce susceptibility to infection compared with the current design. Cite this article: Bone Joint J 2017;99-B:393–400

Dislocation after primary total hip replacement (THR) can occur within days or weeks after the index procedure because of malpositioned components or be of late onset years later due to trauma or excessive wear. Regardless of timing, the culprit causing dislocation is catastrophic neck-cup impingement, which levers the prosthetic head out of the prosthetic socket. Prosthetic range of motion (P-ROM), which is determined by the diameter of the femoral neck at the ball-neck junction and the distance to the edge of the prosthetic cup, must be considered during initial THR insertion to allow internal and external hip rotation of 45° at 90° of hip flexion in neutral abduction-adduction. Failure to achieve satisfactory P-ROM by accurate placement of the acetabular cup and femoral component may result in multiple re-dislocations, especially if periprosthetic capsular reformation is interrupted by an initial dislocation, which disrupts the primary surgical repair. If component position is satisfactory but traumatic disruption of the periprosthetic capsule results in recurrent posterior THR dislocation, a posterior capsular reefing and reinforcement with mersilene tape can be used. A postoperative 30° hip abduction brace with a 60° flexion stop is recommended for continuous use for 6 to 12 weeks. If component position is unsatisfactory or excessive wear causes impingement, removal and repositioning of the acetabular cup in 30° anteversion and 60° abduction with 15° of femoral neck anteversion is recommended

Introduction:. Dislocation is still one of the major complications in total hip arthroplasty. Among other factors, it is important to maximize the intended range of movement (iROM) in order to reduce the risk for prosthetic impingement and to prevent edge loading in order to avoid surface damage and squeaking. Therefore, both components should be positioned in accordance to the new combined safe-zone for correct combined version and inclination aiming for an optimal relative orientation of both components. This study shows how this optimal combined orientation of both components can be determined for a specific total hip prosthetic system and how the result can be transferred to surgery and accomplished intraoperatively using minimal-invasive stem-first technique. Material and Methods:. 829 minimal-invasive total hip arthroplasties have been performed from 2007 to 2013 in our institution. In all of these surgeries a minimal-invasive direct anterior approach (DAA) was applied. All patients were positioned supine on a proprietary orthopedic table. In 168 cases a system-specific mechanical aiming device was used intraoperatively in order to control the combined version and inclination according to the specific safe-zone by orienting the prosthetic socket in relation to the prosthetic stem. This is called “stem-first technique” meaning that the prosthetic stem dictates the orientation of the socket. It does not mean the sequence of implantation. It's specific advantage is that the stem redirects the socket if it's position is modified. It equally applies to standard, anatomic (Fig. 1) or short stems (Fig. 2). The socket orientation is not primarily referred to bony landmarks of the pelvis but to the neck of the stem. Nevertheless the surgeon has to look for sufficient fixation of the socket within the acetabular bone. Leg length was measured in the surgical field additionally and prosthetic offset was adjusted according to the preoperative planning. All other patients were operated on in our standard minimal-invasive DAA-procedure. The majority of the patients suffered from osteoarthritis, their mean age was 68 years. Results:. Optimal component orientation for each prosthesis system was derived from its 3D-model by simulating hip joint motion in the physiologic range of motion. Optimal component orientation means maximizing the area of the combined safe-zone. In the stem-first group cup orientation was in the new combined safe-zone in 94% of the cases and no squeaking or prosthetic impingement did occur in any of these patients. Leg length did not differ more than +/− 5 mm. 83% of all patients receiveda ceramic-on-ceramic articulation, one early dislocation did occur and treated by closed reduction. Conclusion:. Stem-first technique is ideally suited for the minimal-invasive direct anterior approach in total hip arthroplasty to control the combined orientation of the prosthetic components and to achieve excellent clinical results. It assists the surgeon in aligning the cup and the stem according to their correct combined orientation in order to get an optimal range of movement especially in young patients

Background: Osseointegrated amputation prostheses avoid soft tissue complications associated with traditional socket prostheses. Forces are transmitted directly to the skeleton resulting in improved function. However, approximately 50% of transcutaneous implants become infected due to the lack of a successful skin-implant seal. Intraosseous Transcutaneous Amputation Prostheses (ITAP) are designed to integrate with the skin preventing epithelial downgrowth and infection. Fibronectin adsorption enhances fibroblast adhesion in vitro; however, in vivo, fibronectin becomes desorbed from the implant surface. Covalent attachment of fibronectin by silanisation has been shown to be durable in vitro. The silanisation process for fibronectin includes a stage of passivation with sulphuric acid which alters surface characteristics. Aims: The aim of this study was to determine if in vitro fibroblast adhesion to silanised fibronectin (SiFn) titanium alloy could be improved by omitting or reducing the length of time of passivation. The study also assessed the effects of SiFn on dermal attachment in vivo comparing the results with adsorbed fibronectin substrates and with uncoated controls. Methods: Scanning electron microscopy, Ra profilometry and contact angle measurement (n=6) were used for topographical characterization of surfaces. Anti-vinculin antibodies were used to immunolocalize fibroblast adhesion sites after 24 hours. The morphology of fibroblasts on each surface was evaluated using scanning electron microscopy. Subcutaneous plates were implanted onto the tibiae of an ovine model (n=3) in order to evaluate the performance of the modified SiFn surface in vivo. Hydroxyapatite (HA) and adsorption of fibronectin to HA (HAFn) were also tested because HA coatings are currently applied to the dermal section of ITAP in clinical trials. After four weeks, a histological assessment of the percentage of soft-tissue attachment and cell alignment relative to the implant was performed. Results: Passivation produced rougher, more hydrophobic surfaces with numerous microcracks and was associated with poorer fibroblast adhesion and spreading than un-passivated controls in vitro. SiFn with passivation resulted in poorer cell adhesion than SiFn without passivation. Reducing the time period for passivation did not reduce the detrimental effects of passivation In vivo, HAFn and SiFn resulted in higher median values for soft-tissue attachment than simple adsorption of fibronectin; however, the differences were not statistically significant. Cell alignment was significantly different for HAFn and SiFn compared with controls (p< 0.05), with cells on the fibro-nectin treated surfaces orientated more perpendicular to the implant surface. Conclusion: Omission of passivation improves fibro-blast adhesion to SiFn surfaces in vitro. Coating with fibronectin either by silanisation onto titanium alloy or by adsorption onto HA surfaces affected the orientation of cells in vivo, implying that tissue attachment was enhanced. A time course may be of value to determine if fibronectin coatings are lost over time in vivo

The relations among tissue quality, socket discomfort, gait characteristics, and socket pressures are not well established for the unilateral below-knee amputee population. These relations were evaluated for six amputees at seventeen regions of interest on the residual limb. Pressure sensors were placed directly on the residual limb. Peak dynamic socket pressures were not directly related to peak joint moments. However, increases in ground reaction forces (GRFs) related to increases in socket pressures. The relations among tissue quality, socket discomfort, gait characteristics, and socket pressures are not well established for the unilateral below-knee amputee population. The purpose of this study was to evaluate these relations for six amputees. A thorough understanding of pressure distribution between the residual limb and prosthetic socket is critical to socket design and limb health. The subjects ranged in age from thirty to seventy-two years of age. The inclusion criteria were male, unilateral transtibial amputation, ability to ambulate independently, non-diabetic, no debilitating health conditions, non-recent amputee. Tissue sensation and socket discomfort were evaluated at seventeen regions of interest on the residual limb. Tissue sensation was assessed using Semmes-Weinstein monofilaments to test light touch/deep pressure sensation, tuning fork to test vibration sensation, and pinprick to test pain sensation. Socket discomfort was assessed using 10 cm Visual Analogue Scale. Gait characteristics were recorded during walking using a Motion Analysis System. Socket pressure measurements were made using F-socket pressure sensors in conjunction with I-Scan software program. Pressure sensors were placed directly on residual limb. Gait characteristics and socket pressures were compared across three different testing days. The site-specific tissue sensitivity scores did not correlate with the socket discomfort scores. In addition, site-specific discomfort scores did not correlate with peak socket pressures recorded at subject’s normal walking speed. Significant day-to-day pressure differences were found at four of the seventeen areas of interest. Peak dynamic socket pressures were not directly related to peak joint moments. Two subjects demonstrated direct relations between ground reaction forces (GRFs) and socket pressure on the different test days. Funding: NSERC, Workers’ Compensation Board (Alberta), University of Calgary

Aims

Osseointegrated prosthetic limbs allow better mobility than socket-mounted prosthetics for lower limb amputees. Fractures, however, can occur in the residual limb, but they have rarely been reported. Approximately 2% to 3% of amputees with socket-mounted prostheses may fracture within five years. This is the first study which directly addresses the risks and management of periprosthetic osseointegration fractures in amputees.