The purpose of this study is to evaluate the safety and effectiveness of the Transdermal Compress device in participants with Transfemoral Amputations.

This study is a prospective, multicenter, single-arm, open-label study in skeletally mature participants with transfemoral limb loss (unilateral or bilateral), without bone or vascular disease who have or are anticipated to have rehabilitation problems with or cannot use a conventional socket prosthesis.

Study participants will undergo surgical implantation of the Transdermal Compress device on Study Day 1.

Participant progression including clinical assessments and prosthetic use will follow the study rehabilitation protocol.

Events of special interest include superficial and deep infections at the implant site, failures, and secondary surgical interventions; participants will be followed for all soft tissue interface issues.

Participants will be assessed for effectiveness and safety endpoints at baseline and at Months 6, 12, 18, and 24 and annually through 5 years post-implantation.

Adverse events and adverse device effects will be collected and reported starting at the time of surgical implantation.

Study participants will also be included in the Osseointegration Quality Registry in parallel to this study to allow for long-term follow-up post-study.

Inclusion Criteria

1. Participant must be able to understand the investigational nature of this study and has reviewed and provided written, informed consent prior to any study-specific procedures.
2. Participant is a skeletally mature male or female and is 18 - 60 years of age at screening. Participants < 22 years of age require radiographic confirmation of skeletal maturity and must have failed the use of conventional prosthesis.
3. Participant has an estimated BMI of ≥ 18.5 and ≤ 40 kg/m2 and weight ≤ 245 lbs without prosthesis.
4. Participant has unilateral or bilateral transfemoral limb loss without bone or vascular disease.
5. Participant has problems with conventional prostheses or is not able to use a prosthesis at all or is anticipated to experience problems with a socket prosthesis in the investigator's judgment.
6. Participant has adequate bone stock to support the implanted device
7. Participant does not have any cortical defect located between the expected location of the anchor plug and spindle/bone interface.
8. Participant has the willingness, ability, and commitment to participate in baseline and follow-up evaluations for the full length of the study including the prescribed rehabilitation program.

Exclusion Criteria

1. Female participants who are pregnant, nursing, or have a planned pregnancy during the first 12 months post-surgical implantation.
2. Participant had a prior osseointegrated device implanted in the lower limb planned for the study device.
3. Participant has a history of systemic or localized infection at the residual limb site within 6 months prior to Study Day 1.
4. Participant has any distant foci of infections.
5. Participant has a history of sepsis within 6 months prior to Study Day 1.
6. Participant's length of the residual femur cannot accommodate the intramedullary portion of the Transdermal Compress device.
7. Participant has a femoral deformity that in the opinion of the treating surgeon results in an inability to properly insert the Transdermal Compress implant system, and/or results in alignment that is biomechanically unsound.
8. Participant does not have an adequate myofascial flap to allow for circumferential contact with the implanted device.
9. Participant has evidence of or history of severe peripheral vascular disease or insufficiency, muscular atrophy, neuromuscular disease, or diabetes mellitus (Type I or Type II).
10. Participant has evidence of or a documented history of osteomyelitis (excluding the history of osteomyelitis distal to amputation), systemic osteoporosis, or osteomalacia.
11. Participants with identified risk factors for osteoporosis must have a reported T-score > -2.5 within 6 months prior to Study Day 1.
12. Participant has evidence of or a documented history of severe metabolic disorders that may impair bone formation.
13. Participant has a history of systemically administered corticosteroids or immunosuppressive or immunomodulatory therapy or chemotherapy drugs.
14. Participant has known drug or alcohol dependence currently or within the last year.
15. Participant is a smoker, nicotine, or tobacco user in any form or who has used nicotine or tobacco-containing products within the past 6 months prior to Study Day 1.
16. Participant has any other condition, which in the opinion of the Investigator, precludes the participant's participation in the study or the participant is unlikely to comply with the protocol-defined