Osseointegrated total hip replacement connected to a lower limb prosthesis: a proof-of-concept study with three cases

We reported the feasibility of the first three attempts to combine an osseointegrated femoral implant with THR for prosthetic attachment in transfemoral amputees with a short residuum and concomitant osteoporosis.

We are not aware of any alternative techniques for rehabilitation for this group of patients. In these patients, the prosthetic function is usually poor because of reduced muscular control, improper alignment of sockets resulting from the small surface area, and compounded socket-skin interface problems [3, 18]. Consequently, the majority of these patients are confined to a wheelchair because of significantly disabling socket-interface problems when using a standard prosthesis. As is the case for transtibial amputees, a more proximal amputation is not an alternative option because hindquarter amputation would have a substantially negative effect on patient mobility and quality of life [18].

Existing reports suggest the efficacy of osseointegrated implants for transfemoral amputees [14, 25, 31]. However, the patient group described here was not considered candidates for osseointegrated implants because observational data have indicated that the length of the residuum has a significant influence on the outcome; short residuums were associated with a high risk of failure [32]. The presence of osteoporosis is also a contraindication, and data on the use of standard techniques in these patients are lacking.

This novel concept of combining joint replacement with osseointegrated implants was based on involving the proximal joint in implant fixation to provide the necessary surface area for bone-implant contact and subsequent osseointegration. Such an approach allows direct transmission of weight across the joint to the proximal bone, as we demonstrated recently in transtibial amputees [25]. Therefore, this technique not only overcomes the biomechanical challenges in these patients but also restores proximal joint motion in those with arthritis. In the present study, all three cases demonstrated significantly improved functional outcome and mobility. Moreover, the two patients who were confined to a wheelchair before the surgery regained the ability to walk.

To warrant ongoing study of this technique, the clinical benefits observed must outweigh the potential harms. The concept of a bone-anchored metal implant, which may protrude through the skin, raises serious concerns about the risk of ascending infection and its related local and systemic implications, more so than that associated with joint replacement. Therefore, careful soft-tissue management techniques and initial press-fit implantation of the osseointegrated implant are essential to provide a substantial seal to prevent the ascent of infection. Additionally, in our experience, when compared to the short tibial residuum, THR with osseointegration in the short proximal femur presents further surgical challenges related to a higher soft-tissue volume, lack of muscle mass, and low BMD. Therefore, there might be an increased potential for deep infection and subsequent joint infection in this procedure, which remains our foremost concern.

There were no serious adverse events in the present study, although there was one case of superficial infection that was treated using antibiotics. We have recently completed a multicentre study of 86 patients with transfemoral amputations who received osseointegrated implants [16]. A minimum 2-year follow-up revealed that 24 patients experienced a superficial infection that did not require surgery, whereas 5 patients had a deep infection that required soft-tissue debridement. A recent 5-year prospective study (n?=?39) reported a 2 % incidence of deep infection leading to implant removal [15], whereas another study (n?=?51) showed a 50 % cumulative incidence of superficial infections at a 24-month follow-up [5]. However, surgical closing techniques have been developed by us to minimize the risk of deep implant-related infection.

The present study has limitations such as its small sample size and short follow-up duration. However, we have developed a database for comprehensive data collection to enable an assessment of procedural risks and benefits and to identify potential predictors of treatment failure. We envisage that these data might facilitate prospective studies to establish further evidence-based treatment protocols. Longitudinal studies involving a larger cohort over an extended follow-up period are needed to evaluate the long-term outcomes of this novel technique.