Soft-Tissue Contouring and Nerve Management During Lower-Limb Osseointegration Surgery.

Background: Osseointegration provides a direct prosthesis interface for lower-limb amputees, many of whom are poor candidates for traditional socket-suspended prostheses. These skeletally anchored implants eliminate the skin-prosthesis interface, reducing complications such as soft-tissue breakdown, ulceration, and pain¹. Soft-tissue contouring and management of peripheral nerves are essential aspects of osseointegrated implantation surgery for both transfemoral and transtibial amputees. These techniques protect the bone-implant interface, prevent skin-implant friction, and reduce neuroma formation, thus mitigating complications and maximizing patient satisfaction^2,3.

Description: In the present video article, we describe a technique for soft-tissue contouring during single-stage limb osseointegration that involves mobilizing the anterior and posterior musculature to cover the bone-implant interface without excess⁴. Peripheral nerves (i.e., the sciatic and femoral nerves for transfemoral osseointegration and the common peroneal, sural, and posterior tibial nerves for transtibial osseointegration) are identified, and targeted muscle reinnervation (TMR) is performed on each nerve. A regenerative peripheral nerve interface (RPNI) may also be utilized if there is a large size discrepancy during nerve coaptation. We excise redundant soft tissue, performing medial thigh lifts as needed, and resect subscarpal fat to create a posterior skin flap that is advanced over the implant. Finally, a skin aperture is created in the skin flap, through which the implant can attach to the prosthesis. Appropriate tension on the skin aperture is needed to allow for drainage and to avoid necrosis while preventing bacterial ingress into the surgical site.

Alternatives: Alternatives to osseointegration include maximizing the functionality and comfort of a socket prosthesis, either by refitting the prosthesis or by revising the soft tissue of the residual limb. However, both of these strategies have been shown to lead to lower health-related quality of life and are not cost-effective techniques when compared with osseointegration^5,6.

Rationale: Lower-limb osseointegration is particularly beneficial for patients who have the desire to walk and are unable to tolerate traditional socket prostheses because of issues related to poor fit, pain, high metabolic demand, and/or skin breakdown⁷. Osseointegration has been shown to increase quality of life and reduce health-care costs in these patients. The efficacy and outcomes of osseointegration are not impacted by amputation etiology or history of vascular disease, making it a sound option for patients of all backgrounds.

Expected outcomes: Single-institution studies and systematic reviews have shown that lower-limb osseointegration is safe and effective, often resulting in improved mobility and quality of life^8,9. With regard to soft-tissue outcomes, we have demonstrated lower rates of infection (28%) and operative revision (10%) than other institutions, although these complications still pose a challenge for this patient cohort¹⁰. The incidence of infection is particularly high in the first weeks and months postoperatively as the skin aperture begins to heal and seal around the implant. We have also reported a low rate of postoperative neuromas (7%). Although the use of TMR and RPNI has not been formally studied in an osseointegration-specific cohort, these techniques have a strongly positive effect on residual limb pain and phantom limb pain in lower-limb amputees^11,12.

Important tips: Ideally, at least a 4-cm space should be left between the end of the posterior skin flap and the skin aperture in order to minimize the risk of skin necrosis.Insetting the posterior skin flap with quilting sutures allows for enhanced contouring and decreased dead space.RPNI can be utilized in addition to TMR for peripheral nerve management, especially when there is a size mismatch between donor and recipient nerves.Postoperative skin aperture complications can be addressed with topical antibiotics (for infection), silver nitrate (for hypergranulation), and fat grafting and/or steroid injection (for pain).Challenges to adequate peripheral nerve management include failure of the TMR or RPNI to prevent neuroma growth, leading to phantom limb pain and/or residual limb pain.

Acronyms and abbreviations: TMR = targeted muscle reinnervationRPNI = regenerative peripheral nerve interfaceAKA = above-knee amputationBKA = below-knee amputationJP = Jackson-Pratt drainIV = intravenous.