Osseointegration for Amputees: Current Implants, Techniques, and Future Directions

A review of through-knee amputation

OBJECTIVES

Through-knee amputation is an umbrella term for several different surgical techniques, which may affect clinical and functional outcomes. This makes it hard to evaluate the benefits and need for a through-knee amputation approach. This article seeks to (1) determine the number of through-knee amputation performed compared with other major lower limb amputations in England over the past decade; (2) identify the theoretical concepts behind through-knee amputation surgical approaches and their potential effect on functional and clinical outcomes and (3) provide a platform for discussion and research on through-knee amputation and surgical outcomes.

METHODS

National Health Service Hospital Episodes Statistics were used to obtain recent numbers of major lower limb amputations in England. EMBASE and MEDLINE were searched using a systematic approach with predefined criteria for relevant literature on through-knee amputation surgery.

RESULTS

In the past decade, 4.6% of major lower limb amputations in England were through-knee amputations. Twenty-six articles presenting through-knee amputation surgical techniques met our criteria. These articles detailed three through-knee amputation surgical techniques: the classical approach, which keeps the femur intact and retains the patella; the Mazet technique, which shaves the femoral condyles into a box shape and the Gritti-Stokes technique, which divides the femur proximal to the level of the condyles and attaches the patella at the distal cut femur.

CONCLUSIONS

Through-knee amputation has persisted as a surgical approach over the past decade, with three core approaches identified. Studies reporting clinical, functional and biomechanical outcomes of through-knee amputation frequently fail to distinguish between the three distinct and differing approaches, making direct comparisons difficult. Future studies that compare through-knee amputation approaches to one another and to other amputation levels are needed.

Skin adhesion to the percutaneous component of direct bone anchored systems: systematic review on preclinical approaches and biomaterials

Nowadays, direct bone anchored systems are an increasingly adopted approach in the therapeutic landscape for amputee patients. However, the percutaneous nature of these devices poses a major challenge to obtain a stable and lasting proper adhesion between the implant surface and the skin. A systematic review was carried out in three databases (PubMed, Scopus, Web of Science) to provide an overview of the innovative strategies tested with preclinical models (in vitro and in vivo) in the last ten years to improve the skin adhesion of direct bone anchored systems. Fifty five articles were selected after screening, also employing PECO question and inclusion criteria. A modified Cochrane RoB 2.0 tool for the in vitro studies and the SYRCLE tool for in in vivo studies were used to assess the risk of bias. The evidence collected suggests that the implementation of porous percutaneous structures could be one of the most favorable approach to improve proper skin adhesion, especially in association with bioactive coatings, as hydroxyapatite, and exploiting the field of nanostructure. Some issues still remain open as (a) the identification and characterization of the best material/coating association able to limit the shear stresses at the interface and (b) the role of keratinocyte turnover on the skin/biomaterial adhesion and integration processes.

Early Experience with Femoral and Tibial Bone-Anchored Osseointegration Prostheses

Background:

The use of bone-anchored osseointegration implants for amputation reconstruction continues to expand throughout the world. Benefits are thought to include the elimination of socket-related problems and improved control and proprioception of the prosthetic limb. Reported outcomes have been positive, but skepticism remains with regard to the risk of infection and implant failure. Further results from early adopters are therefore needed prior to widespread acceptance and regulatory approval.

Methods:

A retrospective review of the first 31 consecutive patients who underwent implantation of a press-fit osseointegration implant of the femur or tibia with follow-up of at least 6 months was performed. The primary outcome was the patient-reported Questionnaire for persons with a Transfemoral Amputation (Q-TFA) measured preoperatively and 6 to 12 months postoperatively. Patient-Reported Outcomes Measurement Information System (PROMIS) and Limb Deformity-Scoliosis Research Society (LD-SRS) scores, 2-minute and 6-minute walk tests, and complications were also recorded.

Results:

In this study, 18 femoral reconstructions and 13 tibial reconstructions were performed, with a mean follow-up (and standard deviation) of 21.1 ± 9.2 months. Twenty-eight reconstructions were single-stage implantations. All Q-TFA domains improved significantly (p < 0.001) from preoperatively to postoperatively, including the global score (25.0 ± 17.4 to 81.2 ± 17.6 points), prosthetic use (50.2 ± 39.9 to 91.2 ± 18.7 points), prosthetic mobility (49.7 ± 26.9 to 81.4 ± 21.5 points), and prosthetic problems (46.4 ± 17.5 to 9.1 ± 6.6 points). The overall and functional outcome domains of the PROMIS and LD-SRS and the 2-minute walk test (243 ± 107 to 369 ± 151 ft [74 ± 33 to 112 ± 46 m]; p = 0.022) and 6-minute walk test (609 ± 323 to 1,054 ± 555 ft [186 ± 98 to 321 ± 169 m]; p = 0.016) also improved significantly. Serious adverse events included 2 periprosthetic hip fractures, 1 explantation for septic loosening, and 1 explantation for aseptic loosening, with an overall implant retention of 93%. The most common complication was low-grade, soft-tissue infection requiring oral antibiotics.

Conclusions:

Similar to the early experience of other international centers, osseointegration implants improved the overall and functional experience of patients compared with socket prosthetics. Complications were present but manageable and were not a deterrent to ongoing support of the technology.

Level of Evidence:

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Imaging following surgery for primary appendicular bone tumours

Primary bone tumours are uncommon, with sarcomas accounting for < 0.2% of all malignancies. The survival rate of primary bone sarcomas has significantly improved due to (neo)adjuvant therapy, while improved surgical techniques and development of new prostheses have shifted the surgical focus from amputation to limb preservation in the vast majority of patients. A wide variety of surgical options are available for the treatment of primary bone tumours which depend upon histological diagnosis, their appearance at the time of presentation and response to any (neo)adjuvant therapy as required. This review is intended to help radiologists familiarise themselves with the management of primary appendicular bone tumours and expected normal postoperative appearances for the various surgical techniques, and to recognise potential complications.

The Need to Work Arm in Arm: Calling for Collaboration in Delivering Neuroprosthetic Limb Replacements

Over the last few decades there has been a push to enhance the use of advanced prosthetics within the fields of biomedical engineering, neuroscience, and surgery. Through the development of peripheral neural interfaces and invasive electrodes, an individual's own nervous system can be used to control a prosthesis. With novel improvements in neural recording and signal decoding, this intimate communication has paved the way for bidirectional and intuitive control of prostheses. While various collaborations between engineers and surgeons have led to considerable success with motor control and pain management, it has been significantly more challenging to restore sensation. Many of the existing peripheral neural interfaces have demonstrated success in one of these modalities; however, none are currently able to fully restore limb function. Though this is in part due to the complexity of the human somatosensory system and stability of bioelectronics, the fragmentary and as-yet uncoordinated nature of the neuroprosthetic industry further complicates this advancement. In this review, we provide a comprehensive overview of the current field of neuroprosthetics and explore potential strategies to address its unique challenges. These include exploration of electrodes, surgical techniques, control methods, and prosthetic technology. Additionally, we propose a new approach to optimizing prosthetic limb function and facilitating clinical application by capitalizing on available resources. It is incumbent upon academia and industry to encourage collaboration and utilization of different peripheral neural interfaces in combination with each other to create versatile limbs that not only improve function but quality of life. Despite the rapidly evolving technology, if the field continues to work in divided "silos," we will delay achieving the critical, valuable outcome: creating a prosthetic limb that is right for the patient and positively affects their life.

Pelvic Osseointegration for Unilateral Hip Disarticulation: A Case Report

CASE

A 24-year-old man with right unilateral hip disarticulation, intolerant of a traditional socket-mounted prosthesis (TSP), underwent pelvic transcutaneous osseointegration and was fit with a prosthetic lower extremity 7 months later. Twenty-four months after osseointegration, he remains pain-free and complication-free, wears his prosthesis all waking hours, walks without assistive devices and can carry 2-handed objects, and works as a livestock farmer.

CONCLUSION

Through 24 months, the world's first patient with pelvic osseointegration has no complications and better mobility than most patients with unilateral hip disarticulation using TSPs. Pelvic osseointegration seems reasonable to further consider in carefully selected patients.

The bone anchored prostheses for amputees - Historical development, current status, and future aspects

In the past 50 years, bone anchored prostheses have evolved from a concept for experimental treatment to a rapidly developing area in orthopedics and traumatology. Up to date, there are dozens of centers in the world providing osseointegration amputation reconstructions and more than a thousand patients using the bone anchored prostheses. Compared with conventional socket prostheses, the bone anchored prosthesis by osseointegration avoids the debilitating problems related with soft tissues. It also provides physiological weight bearing, improved range of motion, and sensory feedback, all of which contribute to the improvement on quality of life for amputees. The present article briefly reviews the historical development of osseointegration surgery for amputation reconstruction and the current challenges. The implant design characters and surgical techniques of the two types of implants; the screw-type implant (presented by the OPRA system), and the press-fit implants (presented by EEP and OPL systems) are described. The major complications, infections and mechanical failures, are discussed in detail based on the latest evidence. Future aspects and experimental trials aiming to overcome the current challenges are presented.

Osteoimmunology drives dental implant osseointegration: A new paradigm for implant dentistry

There is a complex interaction between titanium dental implants, bone, and the immune system. Among them, specific immune cells, macrophages play a crucial role in the osseointegration dynamics. Infiltrating macrophages and resident macrophages (osteomacs) contribute to achieving an early pro-regenerative peri-implant environment. Also, multinucleated giant cells (MNGCs) in the bone-implant interface and their polarization ability, maintain a peri-implant immunological balance to preserve osseointegration integrity. However, dental implants can display cumulative levels of antigens (ions, nano and microparticles and bacterial antigens) at the implant–tissue interface activating an immune-inflammatory response. If the inflammation is not resolved or reactivated due to the stress signals and the immunogenicity of elements present, this could lead implants to aseptic loosening, infections, and subsequent bone loss. Therefore, to maintain osseointegration and prevent bone loss of implants, a better understanding of the osteoimmunology of the peri-implant environment would lead to the development of new therapeutic approaches. In this line, depicting osteoimmunological mechanisms, we discuss immunomodulatory strategies to improve and preserve a long-term functional integration between dental implants and the human body.

Scientific field of dental science: implant dentistry.

[Transcutaneous osseointegrated prosthetic systems after major amputation of the lower extremity : A retrospective 3-year analysis]

INTRODUCTION

Transcutaneous osseointegrated prosthetic systems (TOPS) are an established optional procedure for the prosthetic treatment of amputations. Under the term endo-exo-prosthesis (EEP), the endosteal adapted exo-prosthesis (Dr. Grundei®) is currently used as the only standard prosthesis for clinical application in Germany. The prosthetic treatment with EEP involves a two-stage surgical procedure. In a first surgical step, the endo-fixed stem is implanted into the bone; in a second operation, approx. 2-6 weeks later, the skin/soft tissue stoma is created, through which the exoprosthetic components can be coupled transcutaneously.

AIM

The aim of this manuscript was to retrospectively collect descriptive 3‑year statistics (2017-2019) from clinical follow-ups and to analyze them with regard to possible effects of TOPS on the mobility level measured by k‑levels. In addition, a brief description of the current standard of care in Germany regarding TOPS will be given.

METHODS

All patients who underwent EEP after major amputation from February 2017 to December 2019 (n = 72, with 76 implants) were included in this study. The data of the EEP patients were collected in standardized follow-ups. K‑levels were compared preoperatively to 6 months postoperatively.

RESULTS

A total of N = 72 patients (N = 76 implantations) was analyzed in the described period. The main cause of amputations was trauma (68.9%). Main complications were myofascial complaints. Implant loosening and deep infections were observed in two cases (2.7%) during this period. Stoma problems occurred with a 3-year average of 25.7%. In terms of K‑levels, there was a high significant increase from preoperative 1.8 ± 0.8 to 3.0 ± 0.4 after a 6-month period.

CONCLUSION

TOPS is an established optional procedure for the treatment of limb loss. In Germany, only one implant is currently regularly implanted (endo-exo prosthesis), and the restoration is currently focused on the lower limb. The restoration of patients with major amputation of the lower extremity by means of TOPS can lead to an increase in mobility and, thus, to an increase in daily activities and participation in daily living.

Amputation With Osseointegration for Patients With Intractable Complex Regional Pain Syndrome: A Report of 3 Cases

CASES

Three patients with knee-level complex regional pain syndrome type 1 (CRPS1), recalcitrant to conservative interventions, elected for transfemoral amputation and osseointegration. Two patients gained independent ambulation; the third remains on crutches after a disrupted sciatic nerve targeted reinnervation. One uses no pain medication, one is weaning off, and one requires a reduced regimen after revision nerve innervation.

CONCLUSION

Osseointegration seems suitable to optimize rehabilitation after amputation for CRPS1.

Targeted Muscle Reinnervation and Osseointegration for Pain Relief and Prosthetic Arm Control in a Woman with Bilateral Proximal Upper Limb Amputation

BACKGROUND

Bilateral proximal upper limb loss is a dramatic life-changing event. Replacement of the lost function with prosthetic arms, including multiple mechatronic joints, has remained a challenge from the control, comfort, and pain management perspectives. Targeted muscle reinnervation (TMR) is a peripheral nerve surgical procedure proposed to improve the intuitive control of the prosthetic arm and for neuroma and phantom pain management. Moreover, osseointegrated percutaneous implants (OPIs) allow for direct skeletal attachment of the prosthetic arm, ensuring freedom of movement to the patient's residual articulations.

CASE DESCRIPTION

We have reported the first combined application of TMR and an OPI to treat a 24-year-old woman with a bilateral amputation at the shoulder level on the right side and at the very proximal transhumeral level on the left side. TMR was performed bilaterally in a single day, accounting for the peculiar patient's anatomy, as preparatory stage to placement of the OPI, and considering the future availability of implantable electromyographic sensors. The 2 OPI surgeries on the left side were completed after 8.5 months, and prosthetic treatment was completed 17 months after TMR.

CONCLUSIONS

The use of TMR resolved the phantom pain bilaterally and the right-side neuroma pain. It had also substantially reduced the left side neuroma pain. The actual prosthetic control result was intuitive, although partially different from expectations. At 2 years after TMR, the patient reported improvement in essential activities of daily living, with a remarkable preference for the OPI prosthesis. Only 1 suspected case of superficial infection was noted, which had resolved. Overall, this combined treatment required a highly competent multidisciplinary team and exceptional commitment by the patient and her family.