Press-Fit Bone-Anchored Prosthesis for Patients with Short Transfemoral Amputation.

Abstract

Background: This video article describes the use of a bone-anchored prosthesis in patients with high above-the-knee amputations resulting in short residual limbs, most typically from trauma, cancer, infections, or dysvascular disease. The use of a socket prosthesis is usually unsuccessful in patients with a high transfemoral amputation because such prostheses have an unstable connection and often require additional waist belts for better attachment to the short residual limb. In most cases, a bone-anchored prosthesis results in substantial improvements in wear time, mobility, and quality of life in these patients. These patients may also be excellent candidates for early osseointegration implant surgery, given the knowledge that socket prostheses are rarely successful.

Description: This procedure is preferably performed in a single stage. After the surgical procedure, most patients stay 1 or 2 nights in the hospital, depending on the magnitude of the surgery (e.g., bilateral implantation of an osseointegration implant) and their comorbidities. Procedure steps include (1) preoperative implant planning, (2) patient positioning and setup, (3) soft-tissue correction (optional) and exposure of residual bone, (4) revision osteotomy with guided shortening, (5) preparation of the medullary canal and perpendicular cutoff plane, (6) marking of the lag screw with a custom-made aiming device and dummy prosthesis, (7) insertion of the intramedullary component with optional bone augmentation, (8) insertion of the lag screw, (9) soft-tissue contouring and closure, and (10) stoma creation and dual cone assembly.

Alternatives: Simultaneous major leg amputation and implantation of an osseointegration prosthesis is not advocated as treatment. First, a rehabilitation program with a socket-suspended prosthesis should be trialed before a patient can apply for a bone-anchored prosthesis. After rehabilitation, satisfaction with a socket prosthesis may be adequate, making a bone-anchored prosthesis unnecessary; however, patients with very short residual limbs and/or irregular soft-tissue conditions may be candidates for early implantation of a bone-anchored prosthesis. Contraindications for osseointegration implant surgery are severe diabetes (with complications), severe bone deformity, immature bone, bone diseases (chronic infection or metastasis), current chemotherapy, severe vascular diseases, pain without a clear cause, body mass index of >30 kg/m², and smoking.

Rationale: About half of patients with a major lower-limb amputation who use an artificial leg are able to function acceptably well with use of a socket-suspended prosthesis; however, in cases with a high transfemoral amputation level, severe limitations may be expected, resulting in reduced prosthesis use, mobility, and quality of life. In these cases, energy transfer from limb to prosthesis is poor because of the so-called pseudojoint, which is the soft-tissue interface, and gross mechanical malalignment is common. These issues lead to complications related to skin irritation and poor socket fit, resulting in decreased overall satisfaction and confidence in mobility. An osseointegration implant creates a direct skeletal connection between the residual limb and artificial leg, in which energy transfer is optimal and mechanical alignment is radically improved.

Expected outcomes: We performed a prospective study with a 1-year follow-up¹. A total of 16 patients with a short residual limb following transfemoral amputation received a gamma-type osseointegration implant with additional lag screw fixation toward the femoral neck. Most patients were male, had a traumatic amputation, and underwent a 2-stage surgery. Prosthesis wear time and patient health-related quality of life were measured with use of the Questionnaire for Persons with a Transfemoral Amputation (QTFA) prosthetic use score and global score, respectively. Both measures improved significantly from baseline to 1-year follow-up. The global score is not applicable for patients who do not use a prosthesis. For the 8 patients (i.e., 50% of the cohort) who did not use a prosthesis at baseline, the third question of the global score (G3 Q3) was utilized instead. This question asks, "How would you summarize your overall situation as an amputee?" As measured with this question, these patients also showed a substantial improvement in quality of life from baseline to 1-year follow-up. Adverse events that can occur following this surgical procedure include infection of the soft tissues and/or bone, periprosthetic fracture, implant breakage, aseptic loosening, and redundancy of soft tissues. In our study, only soft-tissue infections occurred. All superficial soft-tissue infections were successfully treated with use of oral antibiotics. One patient with a deep soft-tissue infection required surgery for abscess drainage. One patient required additional surgery to correct redundancy of soft tissues. Dual-cone adaptor breakage occurred twice; both cases were successfully treated in an outpatient clinic setting. We concluded that the short-term results of this treatment were acceptable. Mid-term follow-up results are currently being collected.

Important tips: Preoperative implant planning should be guided by surgical instructions with a custom-made implant design, with the aim of performing the procedure in a single stage.The use of a traction table may be beneficialLiberally resect soft-tissue redundancy.Utilize water-cooled power sawing.Utilize fluoroscopy to guide drilling.The use of radiographic markers can help guide exact lag screw positioning.In case of little resistance during insertion of the intramedullary component, utilize bone morphogenetic protein-2 (BMP-2; Inductos), bone struts, and/or bone-impaction graftingUtilize a lag screw to increase stabilityDo not close muscle fascia over the implant.Perform a 2-stage procedure only in cases with bone reconstructions, with the stages undertaken at a 10 to 12-week interval.Perform regular postoperative assessment according to your institutional follow-up schedule.

Acronyms and abbreviations: BAP = bone-anchored prosthesisOI = osseointegration implantOFI-Y = custom-made press-fit titanium bone-anchored femur implant (BADAL X; OTN Implants)FL = femur lengthOFI-C = standard press-fit titanium bone-anchored implant (BADAL-X; OTN Implants)CT = computed tomographyDCA = dual-cone adapterK-wire = Kirschner wire.