Changes in periprosthetic bone mineral density and bone turnover markers after osseointegrated implant surgery: A cohort study of 20 transfemoral amputees with 30-month follow-up

A scoring system to evaluate stability of percutaneous osseointegrated implants for transfemoral amputation with validation in the ITAP clinical trial

Percutaneous osseointegrated implants for individuals with lower limb amputation can increase mobility, reduce socket related pain, and improve quality of life. It would be useful to have an evaluation method to assess the interface between bone and implant. We assessed outpatient radiographs from the Intraosseous Transcutaneous Amputation Prosthesis clinical trial using an interface scoring system which summed and weighted equally measures of implant collar cortical ongrowth and radiolucency along the implant stem/bone interface. Radiographs from 12 participants with unilateral transfemoral amputations (10 males, 2 females, mean age = 43.2, SD = 7.4 years) in the clinical trial from cohort I (implanted in 2008/09) or cohort II (implanted in 2013/14) were collated (mean image span = 7.2, SD = 2.4 years), scale normalised, zoned, and measured in a repeatable way. Interface scores were calculated and then compared to clinical outcomes. Explanted participants received the lowest interface scores. A higher ratio of stem to residuum and shorter residuum's produced better interface scores and there was an association (weak correlation) between participants with thin cortices and the lowest interface scores. A tapered, cemented, non curved stem may provide advantageous fixation while stem alignment did not appear critical. In summary, the interface score successfully demonstrated a non-invasive evaluation of percutaneous osseointegrated implants interfaces when applied to the Intraosseous Transcutaneous Amputation Prosthesis clinical trial. The clinical significance of this work is to identify events leading to aseptic or septic implant removal and contribute to clinical guidelines for monitoring rehabilitation, design and surgical fixation choices.

Association between blood markers and the progression of osseointegration in percutaneous prostheses patients-A pilot study

Patients implanted with osseointegrated (OI) prosthetic systems have reported vastly improved upper and lower extremity prosthetic function compared with their previous experience with socket-suspension systems. However, OI systems have been associated with superficial and deep-bone infections and implant loosening due, in part, to a failure of the osseointegration process. Although monitoring the osseointegration using circulating biomarkers has clinical relevance for understanding the progression of osseointegration with these devices, it has yet to be established. Ten patients were enrolled in this study. Blood samples were collected at pre-selected times, starting before implantation surgery, and continuing to 12 months after the second surgery. Bone formation markers, bone resorption markers, and circulating amino acids were measured from blood samples. A linear mixed model was generated for each marker, incorporating patient ID and age with the normalized marker value as the response variable. Post hoc comparisons were made between 1 week before Stage 1 Surgery and all subsequent time points for each marker, followed by multiple testing corrections. Serial radiographic imaging of the residual limb containing the implant was obtained during follow-up, and the cortical index (CI) was calculated for the bone at the porous region of the device. Two markers of bone formation, specifically bone-specific alkaline phosphatase (Bone-ALP) and amino-terminal propeptide of type I procollagen (PINP), exhibited significant increases when compared with the baseline levels of unloaded residual bone prior to the initial surgery, and they subsequently returned to their baseline levels by the 12-month mark. Patients who experienced clinically robust osseointegration experienced increased cortical bone thickness at the porous coated region of the device. A medium correlation was observed between Bone-ALP and the porous CI values up to PoS2-M1 (p = .056), while no correlation was observed for PINP. An increase in bone formation markers and the lack of change observed in bone resorption markers likely reflect increased cortical bone formation induced by the end-loading design of the Utah OI device used in this study. A more extensive study is required to validate the correlation observed between Bone-ALP and porous CI values.

Bone Mineral Density T-Score is an Independent Predictor of Major Blood Loss in Adult Spinal Deformity Surgery

STUDY DESIGN

Retrospective Cohort Study.

OBJECTIVE

The purpose of this study was to determine the effect of low bone mineral density (BMD), as assessed by preoperative Dual-energy X-ray Absorptiometry (DEXA) scans, on intraoperative blood loss following adult spinal deformity (ASD) surgery.

METHODS

Patients who received spinal fusion for ASD (>5 levels fused) at a single academic center from 2010-2018 were included in this study. The lowest preoperative T-score was recorded for patients who had preoperative DEXA scans within a year of surgery. Patients with liver/kidney disease or on prescription anticoagulant medication were excluded. Major blood loss was a binary variable defined as above or below the 90th percentile of our cohort. Binomial regression was performed controlling for age, number of vertebrae fused, 3-column osteotomy, primary vs. revision surgery, preoperative platelet count, and if the patient was taking medication for osteoporosis.

RESULTS

91 patients were identified in the cohort. Mean age was 63 ± 11.6 years, 81% female. 56 (62%) of cases included revision of previous instrumentation. Patients had a mean SVA of 9.6 ± 8.6 cm and median of 9 vertebrae fused (range 5-22). The average T-score was -1.2 ± 1.0. Each point lower T-score was associated with significantly higher odds of major blood loss (OR 2.5, 95% CI 1.0 - 5.9) when controlling for age, number of vertebrae fused, 3-column osteotomy, preoperative platelet count and primary vs. revision surgery.

CONCLUSIONS

Preoperative T-score is independently associated with increased odds of major blood loss in ASD surgery.

Association Between Combat-Related Traumatic Injury and Skeletal Health: Bone Mineral Density Loss Is Localized and Correlates With Altered Loading in Amputees: the Armed Services Trauma Rehabilitation Outcome (ADVANCE) Study

The association between combat-related traumatic injury (CRTI) and bone health is uncertain. A disproportionate number of lower limb amputees from the Iraq and Afghanistan conflicts are diagnosed with osteopenia/osteoporosis, increasing lifetime risk of fragility fracture and challenging traditional osteoporosis treatment paradigms. The aim of this study is to test the hypotheses that CRTI results in a systemic reduction in bone mineral density (BMD) and that active traumatic lower limb amputees have localized BMD reduction, which is more prominent with higher level amputations. This is a cross-sectional analysis of the first phase of a cohort study comprising 575 male adult UK military personnel with CRTI (UK-Afghanistan War 2003 to 2014; including 153 lower limb amputees) who were frequency-matched to 562 uninjured men by age, service, rank, regiment, deployment period, and role-in-theatre. BMD was assessed using dual-energy X-ray absorptiometry (DXA) scanning of the hips and lumbar spine. Femoral neck BMD was lower in the CRTI than the uninjured group (T-score -0.08 versus -0.42 p = .000). Subgroup analysis revealed this reduction was significant only at the femoral neck of the amputated limb of amputees (p = 0.000), where the reduction was greater for above knee amputees than below knee amputees (p < 0.001). There were no differences in spine BMD or activity levels between amputees and controls. Changes in bone health in CRTI appear to be mechanically driven rather than systemic and are only evident in those with lower limb amputation. This may arise from altered joint and muscle loading creating a reduced mechanical stimulus to the femur resulting in localized unloading osteopenia. This suggests that interventions to stimulate bone may provide an effective management strategy. © 2023 Crown copyright and The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR). This article is published with the permission of the Controller of HMSO and the King's Printer for Scotland.

Bone density changes after five or more years of unilateral lower extremity osseointegration: Observational cohort study

Context

Rehabilitation following lower extremity amputation presents multiple challenges, many related to the traditional prosthesis (TP) socket. Without skeletal loading, bone density also rapidly decreases. Transcutaneous osseointegration for amputees (TOFA) surgically implants a metal prosthesis attachment directly into the residual bone, facilitating direct skeletal loading. Quality of life and mobility are consistently reported to be significantly superior with TOFA than TP.

Objective

To investigate how femoral neck bone mineral density (BMD, g/cm²) changes for unilateral transfemoral and transtibial amputees at least five years following single-stage press-fit osseointegration.

Methods

Registry review was performed of five transfemoral and four transtibial unilateral amputees who had dual x-ray absorptiometry (DXA) performed preoperatively and after at least five years. The average BMD was compared using Student's t-test (significance p < .05). First, all nine Amputated versus Intact limbs. Second, the five patients with local disuse osteoporosis (ipsilateral femoral neck T-score < -2.5) versus the four whose T-score was greater than -2.5.

Results

The average Amputated Limb BMD was significantly less than the Intact Limb, both Before Osseointegration (0.658 ± 0.150 vs 0.929 ± 0.089, p < .001) and After Osseointegration (0.720 ± 0.096 vs 0.853 ± 0.116, p = .018). The Intact Limb BMD decreased significantly during the study period (0.929 ± 0.089 to 0.853 ± 0.116, p = .020), while the Amputated Limb BMD increased a not statistically significant amount (0.658 ± 0.150 to 0.720 ± 0.096, p = .347). By coincidence, all transfemoral amputees had local disuse osteoporosis (BMD 0.545 ± 0.066), and all transtibial patients did not (BMD 0.800 ± 0.081, p = .003). The local disuse osteoporosis cohort eventually had a greater average BMD (not statistically significant) than the cohort without local disuse osteoporosis (0.739 ± 0.100 vs 0.697 ± 0.101, p = .556).

Conclusions

Single-stage press-fit TOFA may facilitate significant BMD improvement to unilateral lower extremity amputees with local disuse osteoporosis.

Osseointegrated prostheses for the rehabilitation of patients with transfemoral amputations: A prospective ten-year cohort study of patient-reported outcomes and complications

Background

Methods

Results

Conclusion

What Are the Risk Factors for Mechanical Failure and Loosening of a Transfemoral Osseointegrated Implant System in Patients with a Lower-limb Amputation?

BACKGROUND

Septic loosening and stem breakage due to metal fatigue is a rare but well-known cause of orthopaedic implant failure. This may also affect the components of the osseointegrated implant system for individuals with transfemoral amputation who subsequently undergo revision. Identifying risk factors is important to minimize the frequency of revision surgery after implant breakage.

QUESTIONS/PURPOSES

(1) What proportion of patients who received an osseointegrated implant after transfemoral amputation underwent revision surgery, and what were the causes of those revisions? (2) What factors were associated with revision surgery when stratified by the location of the mechanical failure and (septic) loosening (intramedullary stem versus dual cone adapter)?

METHODS

Between May 2009 and July 2015, we treated 72 patients with an osseointegrated implant. Inclusion criteria were a minimum follow-up of 5-years and a standard press-fit cobalt-chromium-molybdenum (CoCrMb) transfemoral osseointegrated implant. Based on that, 83% (60 of 72) of patients were eligible; a further 3% (2 of 60) were excluded because of no received informed consent (n = 1) and loss to follow-up (n = 1). Eventually, we included 81% (58 of 72) of patients for analysis in this retrospective, comparative study. We compared patient characteristics (gender, age, and BMI), implant details (diameter of the intramedullary stem, length of the dual cone, and implant survival time), and event characteristics (infectious complications and distal bone resorption). The data were retrieved from our electronic patient file and from our cloud-based database and analyzed by individuals not involved in patient care. Failures were categorized as: (1) mechanical failures, defined as breakage of the intramedullary stem or dual-cone adapter, or (2) (septic) loosening of the osseointegrated implant.

RESULTS

Thirty-four percent (20 of 58) of patients had revision surgery. In 12% (7 of 58) of patients, the reason for revision was due to intramedullary stem failures (six breakages, one septic loosening), and in 22% (13 of 58) of patients it was due to dual-cone adaptor failure (10 weak-point breakages and four distal taper breakages; one patient broke both the weak-point and the dual-cone adapter). Smaller median stem diameter (failure: 15 mm [interquartile range 1.3], nonfailure: 17 mm [IQR 2.0], difference of medians 2 mm; p < 0.01) and higher median number of infectious events (failure: 6 [IQR 11], nonfailure: 1 [IQR 3.0], difference of medians -5; p < 0.01) were associated with revision intramedullary stem surgery. No risk factors could be identified for broken dual-cone adapters.

CONCLUSION

Possible risk factors for system failure of this osteointegration implant include small stem diameter and high number of infectious events. We did not find factors associated with dual-cone adapter weak-point failure and distal taper failure, most likely because of the small sample size. When treating a person with a lower-limb amputation with a CoCrMb osseointegrated implant, we recommend avoiding a small stem diameter. Further research with longer follow-up is needed to study the success of revised patients.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Rehabilitation of Patients with Osseointegrated Prosthesis after Transfemoral Amputation - Literature-based Recommendation for Postoperative Rehabilitative Procedure

BACKGROUND

Osseointegrative implantation after amputation of the lower extremity is a special treatment option. Physiotherapeutic treatment is important for the functional outcome. This study systematically evaluated existing follow-up treatment protocols to establish a literature-based recommendation for postoperative rehabilitation procedures.

METHODOLOGY

A PubMed literature search was conducted on December 10, 2020, using the following search terms: (osseo-integrat* OR endo-exo OR boneanchored OR bone anchored) AND (prosthe*) AND (leg OR lower limb* OR lower extremit* OR transfem* OR transtib*) AND (rehabilitation). 113 publications were found in this context. 10 of them met inclusion criteria. The Cochrane risk of bias tool was used to determine the publications' quality.

RESULTS

Three systematic rehabilitation protocols have been described: Osseointegrated Prostheses for the Rehabilitation of Amputees protocol, Osseointegration Group of Australia Accelerated protocol and Radboud Amputation: rehabilitation protocol for endo-exo femoral prosthesis. There are clear differences in the duration of the rehabilitation protocols. The quality of published studies is limited due to the high risk of bias and low evidence levels (mainly III - V). A concept for long-term rehabilitation has not been described yet.

CONCLUSIONS

There are various protocols for rehabilitation after treatment with osseointegrative prosthesis. Gradually increasing axial weight bearing started shortly after surgery; step-by-step gait training, adaptation of the prosthesis to the new biomechanics and critical patient selection and pre-operative training have been proven useful for successful rehabilitation. Controlled comparative studies, standardised outcome measurements or comparative studies between different protocols are not available. Models for multi-level long-term care have not been described in the literature so far.

Lower limb prosthetic interfaces: Clinical and technological advancement and potential future direction

The human-prosthesis interface is one of the most complicated challenges facing the field of prosthetics, despite substantive investments in research and development by researchers and clinicians around the world. The journal of the International Society for Prosthetics and Orthotics, Prosthetics and Orthotics International, has contributed substantively to the growing body of knowledge on this topic. In celebrating the 50th anniversary of the International Society for Prosthetics and Orthotics, this narrative review aims to explore how human-prosthesis interfaces have changed over the last five decades; how research has contributed to an understanding of interface mechanics; how clinical practice has been informed as a result; and what might be potential future directions. Studies reporting on comparison, design, manufacturing and evaluation of lower limb prosthetic sockets, and osseointegration were considered. This review demonstrates that, over the last 50 years, clinical research has improved our understanding of socket designs and their effects; however, high-quality research is still needed. In particular, there have been advances in the development of volume and thermal control mechanisms with a few designs having the potential for clinical application. Similarly, advances in sensing technology, soft tissue quantification techniques, computing technology, and additive manufacturing are moving towards enabling automated, data-driven manufacturing of sockets. In people who are unable to use a prosthetic socket, osseointegration provides a functional solution not available 50 years ago. Furthermore, osseointegration has the potential to facilitate neuromuscular integration. Despite these advances, further improvement in mechanical features of implants, and infection control and prevention are needed.